ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 BIOWAX EMULSIONS AS BIO‐BASED BARRIER COATING DISPERSIONS RELATED APPLICATIONS [0001] The present application claims benefit of priority to US Provisional Application No.: 63/456,167, filed on March 31, 2024, and to Finnish Application Number 20235948 filed on August 28, 2023, the contents of both of which are incorporated by reference in their entireties. FIELD OF THE INVENTION [0002] The present invention relates to compositions and methods for forming substantially bio‐ based barrier coatings e.g., for application on paper and board substrates. In particular, the disclosure provides biowax‐based barrier compositions that can form barrier layers for enhancing oil, grease, and water resistance and can be applied without causing damage to the substrate. BACKGROUND OF THE INVENTION [0003] Various coatings can be applied on the surface of paper or board in order to improve their properties. Oil, grease, water, and water vapor barrier properties are particularly important for paper and board that are used for products for packaging purposes. Coating applied on the surface of paper or board should provide an effective barrier for leakage from the goods inside the package and/or protect the packaged goods from contamination and/or contact with the surrounding atmosphere. For packaging materials used for foodstuff and consumable liquids the barrier requirements are especially stringent. [0004] The barrier resistance and wettability of paper or board is commonly controlled by the application of petroleum‐based derivatives and polymers such as polyacrylates, polyethylene, ethylene vinyl alcohol (EVOH), polyvinylidene chloride (PVDC), petroleum waxes, and/or fluorocarbon derivatives as coatings. Coatings of petroleum‐based polymer emulsions have been used in food or beverage packaging, such food packages made from paper, plates, bowls, cups, and containers. Barrier coatings based on fossil‐oil or synthetic polymers dominate the current market due to low‐cost and easy availability. Such coatings may be applied using conventional printing or coating techniques. [0005] While surface hydrophobicity, water resistance, and oil/grease resistance (OGR) are improved by employing petroleum‐based polymers, they have become disfavored due to limitations in fossil‐oil resources, poor recyclability, and environmental concerns on generated waste with lack of biodegradation. Because packaging paper for food and beverage is often used only once, it is desirable for ecological reasons that the coating compositions for packaging be produced from sustainably sourced, renewable, bio‐based materials. Additionally, consumer‐based demand for sustainable and renewable bio‐based paper and paperboard barrier coating products has increased dramatically in recent years. Generally, coating dispersions with greater than 50 wt% bio‐content can be certified and labeled as a bio‐based product in the market. [0006] These factors have augmented the interest in alternative biopolymer films and coatings with similar properties to petroleum based coatings. There is a tendency for paper coating producers to
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 replace fossil based chemistries with bio‐based materials in their current barrier coating polymer emulsions. [0007] As an alternative to petroleum‐based derivatives, biopolymers including polysaccharides, proteins, and polyesters, and bio‐based waxes (i.e., biowaxes), including hydrogenated bio‐based oils and biolipids can be used to formulate new compositions for forming substantially bio‐based barrier coatings for paper and board. These bio‐based materials as barrier coatings for paper applications have the potential to replace current fossil‐oil barrier coating materials. However, difficulties in processing of most biopolymers may arise due to hydrophilicity, crystallization behavior, high viscosity, unfavorable rheology, brittleness, and/or melt instabilities that hinder a full exploitation at industrial scale. [0008] Biowaxes, including hydrogenated bio‐based oils (vegetable oils and animal oils) have been successfully used to make bio‐based coating materials for paper applications. Biowax comprising barrier coatings as described herein, when used to directly coat paper/paperboard, exhibit a marked increase in the resistance to oil, grease, and water moisture. However, most commercial biowax liquid formulations must be applied on paper surfaces at temperatures between 80 and 160 °C, using wax applicators or other special equipment. When applied at elevated temperatures, biowax liquids tend to (i) destroy paper fiber strengths and (ii) cause discoloration of the paper. [0009] There is currently an unmet need in the market for substantially bio‐based barrier coatings for paper and board, which (i) are stable dispersions, (ii) have a high bio‐based content (>50% of total coating solids), and (iii) can be applied using conventional paper coaters or metering size press machines under room temperature conditions without causing damage or discoloration to the paper/paperboard substrate. Making such stable and high bio‐content coating dispersions remains a challenge. [0010] The present application addresses this challenge by providing novel compositions and methods for forming substantially bio‐based barrier coatings for paper and board. The invention provides biowax‐based barrier compositions that can form barrier layers for enhancing oil, grease, and water resistance which can be applied without causing damage to the substrate and which deliver a sustainable bio‐based barrier coating solution to potentially replace or minimize the need for conventional petroleum based coatings. SUMMARY OF THE INVENTION [0011] The present invention relates to compositions and methods for forming substantially bio‐ based barrier coatings, e.g., for application on paper and board substrates, e.g., those comprised of recycled fibers. [0012] Biowax emulsions, polyacrylate dispersions, and other additives are employed to form barrier coating compositions having long shelf life, high solids content, high bio‐based content, and rheological properties that facilitate application as barrier coatings using conventional methods at room temperature. Barrier coating compositions comprising a biowax emulsion dispersed into one or more polyacrylate carriers with one or more rheology modifiers and auxiliary additives (e.g., clay, MCC, and the like), when used to coat paper and/or board achieved excellent oil and water barrier
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 properties including (i) greater than 50% bio‐content (renewable raw material) in two coating layers, (ii) Cobb value (30 min) of two‐layer coated sheets < 5 g/m2; and (iii) KIT value = 12. [0013] In one aspect, the present invention provides a barrier coating composition for paper or board, said barrier coating composition comprising: [0014] (a) one or more biowax emulsions; [0015] (b) one or more polyacrylate carriers; and [0016] (c) optionally, one or more auxiliary additives, [0017] wherein said one or more biowax emulsions comprise: [0018] (i) one or more biowaxes optionally comprising palm oil wax, castor oil wax, soybean oil wax, fish oil wax, tallow oil wax, a plant oil wax, an animal oil wax, a blend of plant and animal oil waxes, or any combination thereof; [0019] (ii) one or more rosin sizing agents optionally comprising fortified rosins, esterified rosins, rosin waxes, resin acid derivatives, gum rosins, wood rosins, tall oil rosins, rosin pastes, rosin‐based dispersants, or any combination thereof; [0020] (iii) one or more surfactants optionally comprising one or more nonionic surfactants, one or more anionic surfactants, or a combination thereof, wherein (a) said one or more nonionic surfactants comprise ethoxylated alcohols, including but not limited to, secondary alcohol ethoxylates, ethoxylated sorbitan esters, sorbitan esters, glycerol esters, including but not limited to, glycerol monostearate (GMS), and any combination thereof, and (b) said one or more anionic surfactants comprise fatty alcohol ether sulfates, alkyl ether sulfates, special soaps, including but not limited to, anionic long chain fatty acids, and any combination thereof; [0021] (iv) one or more microcrystalline or paraffinic waxes optionally comprising saturated hydrocarbon waxes, paraffinic hydrocarbon waxes, isoparaffinic hydrocarbon waxes, naphthenic hydrocarbon waxes, and a mixture thereof, having a congealing point of 50‐110 °C, 65‐100 °C, 70‐ 90 °C, or 75‐85 °C; and [0022] (v) optionally, one or more long chain fatty acids having a carbon chain length ranging from C18‐C30, C20‐C30, C22‐C30, or C24‐C30. [0023] In some embodiments the barrier coating composition further comprises one or more rheology modifiers. [0024] In some exemplary embodiments said one or more biowaxes: [0025] (a) comprise one or more hydrogenated bio‐based oils including, but not limited to, palm oil, castor oil, soybean oil, fish oil, tallow oil, a plant oil, an animal oil, a blend of plant and animal oils, or any combination thereof, and wherein each of said hydrogenated bio‐based oils has a higher melting point compared to the corresponding non‐hydrogenated bio‐based oil; and [0026] (b) has a melting point of 55‐98 °C, 60‐95 °C, 65‐90 °C, 70‐85 °C, or 75‐80 °C. [0027] In some exemplary embodiments according to any of the foregoing, in said one or more biowax emulsions:
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0028] (a) said one or more biowaxes comprises castor oil wax; [0029] (b) said one or more rosin sizing agents comprises fortified rosin size; [0030] (c) said nonionic surfactants comprise secondary alcohol ethoxylates, glycerol monostearate (GMS), or a combination thereof and said anionic surfactants comprise anionic long chain fatty acids, or a combination thereof; [0031] (d) said one or more microcrystalline or paraffinic waxes has a congealing point of 70‐90 °C; and [0032] (e) said one or more long chain fatty acids has a carbon chain length ranging from C22‐C30. [0033] In some exemplary embodiments according to any of the foregoing said one or more biowax emulsions comprise: [0034] (a) said one or more biowaxes in an amount ranging from 20‐60 wt%, 25‐55 wt%, 30‐50 wt%, or 35‐45 wt%; [0035] (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%; [0036] (c) said one or more surfactants in an amount ranging from 2‐12 wt%, 4‐10 wt%, or 6‐8 wt%; [0037] (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 [0038] (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%. [0039] In some exemplary embodiments according to any of the foregoing said one or more biowax emulsions comprise an inverse phase biowax emulsion formed by: [0040] (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; [0041] (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; [0042] (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; [0043] (d) homogenizing; [0044] (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 [0045] (f) optionally adding a biocide. [0046] In some exemplary embodiments according to any of the foregoing said one or more biowax emulsions, in final form:
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0047] (a) comprise a total solids content ranging from 50‐80 wt%, 50‐70 wt%, 50‐60 wt%, or 55‐57 wt% and further wherein ≥ 50 wt% of said total solids content is bio‐based; and/or [0048] (b) have a final bulk viscosity ranging from 1400‐1800 cPs, 1500‐1700 cPs, 1550‐1650 cPs, or 1590‐1610 cPs. [0049] In some exemplary embodiments according to any of the foregoing: [0050] (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%, [0051] (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; [0052] (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; [0053] (d) any combination of (a), (b) and (c). [0054] In some exemplary embodiments according to any of the foregoing, in said one or more auxiliary additives: [0055] (a) said clay and/or nano‐clay is formulated as an aqueous slurry having total solids of 60‐80 wt%, 65‐75 wt%, or 68‐72 wt% prior to being dispersed into said barrier coating composition; [0056] (b) said cellulose nanocrystals (CNC) is formulated as an aqueous slurry or a spray‐dried powder prior to being dispersed into said barrier coating composition, and is optionally produced by acid hydrolysis of cellulose; [0057] (c) said micro‐fibrillated cellulose (MFC) (i) has an average particle length ranging from 20‐ 200 µm, 50‐200 µm, 100‐200 µm, or 150‐200 µm, (ii) has an average particle width ranging from 0.1‐ 1 µm, 0.2‐1 µm, 0.4‐1 µm, or 0.6‐1 µm, and (iii) is formulated as an aqueous solution having a dry content of 10‐30 wt%, 15‐25 wt%, or 18‐22 wt% prior to formulation with said barrier coating composition; [0058] (d) said microcrystalline cellulose (MCC) (i) has an average particle size ranging from 1‐8 µm, 2‐7 µm, 3‐6 µm, or 4‐5 µm, and (ii) is formulated as an aqueous slurry or a spray‐dried powder prior to being dispersed into said barrier coating composition. [0059] In some exemplary embodiments according to any of the foregoing: [0060] (a) said one or more rheology modifiers comprises pre‐hydrated cellulose gums and xanthan gums; and
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0061] (b) said one or more auxiliary additives comprises clay, nano‐clay, microcrystalline cellulose (MCC), or a combination thereof. [0062] In some exemplary embodiments according to any of the foregoing said barrier coating composition comprises: [0063] (a) said one or more biowax emulsions in an amount ranging from 20‐80 wt%, 30‐70 wt%, or 40‐60 wt%; [0064] (b) said one or more polyacrylate carriers in an amount ranging from 20‐80 wt%, 30‐70 wt%, or 40‐60 wt%; [0065] (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 [0066] (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. [0067] In some exemplary embodiments according to any of the foregoing 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: [0068] (a) comprises a total solids content ranging from 30‐70 wt%, 40‐60 wt%, 45‐55 wt%, or 48‐52 wt%; [0069] (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; [0070] (c) has a particle size ranging from 0.2‐5 µm, 1‐4 µm, 2‐3 µm, or 2.5‐3 µm; [0071] (d) has a bulk viscosity ranging from 40‐800 cPs, 100‐700 cPs, 150‐650 cPs, or 200‐400 cPs; [0072] (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 [0073] (f) any combination of one, two, three, four or all five of (a) to (e). [0074] In some exemplary embodiments according to any of the foregoing the barrier coating composition, 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: [0075] (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
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 coating composition, a double‐coating comprising a basecoat layer and a topcoat layer comprising different barrier coating compositions, or multiple coating layers; [0076] (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; [0077] (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; [0078] (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; [0079] (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 [0080] (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%. [0081] In another aspect, the present invention provides a method for preparing a barrier coating composition for paper or board, optionally according to any of the foregoing compositions, the method comprising: [0082] (a) forming at least one biowax emulsion; [0083] (b) forming or providing one or more polyacrylate carriers; [0084] (c) dispersing said at least one biowax emulsion into said one or more polyacrylate carriers; [0085] (d) optionally, dispersing one or more rheology modifiers into said one or more polyacrylate carriers; and [0086] (e) optionally, dispersing one or more auxiliary additives into said one or more polyacrylate carriers; [0087] wherein steps (c)‐(e) are effected together or separately. [0088] In some exemplary embodiments of the method said at least one biowax emulsion comprises: [0089] (a) one or more biowaxes selected from the group consisting of palm oil wax, castor oil wax, soybean oil wax, fish oil wax, tallow oil wax, a plant oil wax, an animal oil wax, a blend of plant and animal oil waxes, or any combination thereof, wherein said one or more biowaxes (i) comprises one or more hydrogenated bio‐based oils including, but not limited to, palm oil, castor oil, soybean oil, fish oil, tallow oil, a plant oil, an animal oil, a blend of plant and animal oils, or any combination thereof, wherein each of said hydrogenated bio‐based oils has a higher melting point compared to
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 the corresponding non‐hydrogenated bio‐based oil and (ii) has a melting point of 55‐98 °C, 60‐95 °C, 65‐90 °C, 70‐85 °C, or 75‐80 °C; [0090] (b) one or more rosin sizing agents, including but not limited to, fortified rosins, esterified rosins, rosin waxes, resin acid derivatives, gum rosins, wood rosins, tall oil rosins, rosin pastes, rosin‐ based dispersants, or any combination thereof; [0091] (c) one or more surfactants comprising nonionic surfactants, anionic surfactants, or a combination thereof, wherein (i) said nonionic surfactants are selected from ethoxylated alcohols, including but not limited to, secondary alcohol ethoxylates, ethoxylated sorbitan esters, sorbitan esters, glycerol esters, including but not limited to, glycerol monostearate (GMS), and any combination thereof, and (ii) said anionic surfactants are selected from, fatty alcohol ether sulfates, alkyl ether sulfates, special soaps, including but not limited to, anionic long chain fatty acids, and any combination thereof; [0092] (d) one or more microcrystalline or paraffinic waxes, including but not limited to saturated hydrocarbon waxes, paraffinic hydrocarbon waxes, isoparaffinic hydrocarbon waxes, naphthenic hydrocarbon waxes, and a mixture thereof, having a congealing point of 50‐110 °C, 65‐100 °C, 70‐ 90 °C, or 75‐85 °C; and [0093] (e) optionally, one or more long chain fatty acids having a carbon chain length ranging from C18‐C30, C20‐C30, C22‐C30, or C24‐C30. [0094] In some exemplary embodiments of the method said at least one biowax emulsion comprises: [0095] (a) said one or more biowaxes in an amount ranging from 20‐60 wt%, 25‐55 wt%, 30‐50 wt%, or 35‐45 wt%; [0096] (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%; [0097] (c) said one or more surfactants in an amount ranging from 2‐12 wt%, 4‐10 wt%, or 6‐8 wt%; [0098] (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 [0099] (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%, [0100] wherein said at least one biowax emulsion comprises an inverse phase biowax emulsion formed by [0101] (i) 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; [0102] (ii) 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;
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0103] (iii) 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; [0104] (iv) homogenizing; [0105] (v) cooling the resulting inverse phase biowax emulsion to a temperature ranging from 10‐ 35 °C, 15‐30 °C, or 20‐25 °C, optionally by means of an ice‐water bath, a cooling jacket, or a cooling core; and [0106] (vi) optionally adding a biocide. [0107] In some exemplary embodiments of the method said at least one biowax emulsion, in final form: [0108] (a) comprises a total solids content ranging from 50‐80 wt%, 50‐70 wt%, 50‐60 wt%, or 55‐57 wt% and further wherein ≥ 50 wt% of said total solids content is bio‐based; and [0109] (b) has a final bulk viscosity ranging from 1400‐1800 cPs, 1500‐1700 cPs, 1550‐1650 cPs, or 1590‐1610 cPs. [0110] In some exemplary embodiments of the method: [0111] (a) said one or more polyacrylate carriers comprises 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%, [0112] (b) said one or more rheology modifiers comprises 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; and [0113] (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, [0114] wherein [0115] (i) said clay and/or nano‐clay is formulated as an aqueous slurry having total solids of 60‐80 wt%, 65‐75 wt%, or 68‐72 wt% prior to being dispersed into said barrier coating composition using a mechanical mixing device; [0116] (ii) said cellulose nanocrystals (CNC) is formulated as an aqueous slurry or a spray‐dried powder prior to being dispersed into said barrier coating composition using a mechanical mixing device, and is optionally produced by acid hydrolysis of cellulose; [0117] (iii) said micro‐fibrillated cellulose (MFC) (i) has an average particle length ranging from 20‐ 200 µm, 50‐200 µm, 100‐200 µm, or 150‐200 µm, (ii) has an average particle width ranging from 0.1‐ 1 µm, 0.2‐1 µm, 0.4‐1 µm, or 0.6‐1 µm, and (iii) is formulated as an aqueous solution having a dry
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 content of 10‐30 wt%, 15‐25 wt%, or 18‐22 wt% prior to formulation with said barrier coating composition; and [0118] (iv) said microcrystalline cellulose (MCC) (i) has an average particle size ranging from 1‐8 µm, 2‐7 µm, 3‐6 µm, or 4‐5 µm, and (ii) is formulated as an aqueous slurry or a spray‐dried powder prior to being dispersed into said barrier coating composition using a mechanical mixing device. [0119] In some exemplary embodiments of the method said barrier coating composition comprises: [0120] (a) said at least one biowax emulsion in an amount ranging from 20‐80 wt%, 30‐70 wt%, or 40‐60 wt%; [0121] (b) said one or more polyacrylate carriers in an amount ranging from 20‐80 wt%, 30‐70 wt%, or 40‐60 wt%; [0122] (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 [0123] (d) optionally, 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, [0124] wherein said at least one biowax emulsion, said one or more rheology modifiers, and optionally said one or more auxiliary additives are dispersed, separately or together, into said one or more polyacrylate carriers with mechanical mixing to form said barrier coating composition, wherein, in final form, said barrier coating composition [0125] (i) comprises a total solids content ranging from 30‐70 wt%, 40‐60 wt%, 45‐55 wt%, or 48‐52 wt%; [0126] (ii) 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; [0127] (iii) has a particle size ranging from 0.2‐5 µm, 1‐4 µm, 2‐3 µm, or 2.5‐3 µm; [0128] (iv) has a bulk viscosity ranging from 40‐800 cPs, 100‐700 cPs, 150‐650 cPs, or 200‐400 cPs; [0129] (v) comprises a stable dispersion having a stability greater than 3 months at 25 °C, wherein stability is determined by said barrier coating composition maintaining a 3 month aged viscosity within ±50%, ±40%, ±30%, or ±20% of said bulk viscosity in (iv); or [0130] (vi) any combination of one, two, three, four or all five of (a) to (e). [0131] In some exemplary embodiments of the method said barrier coating composition is 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, and wherein application of said barrier coating composition results in one or more of the following:
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0132] (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; [0133] (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; [0134] (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; [0135] (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; [0136] (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 [0137] (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%. [0138] In another aspect, the present invention also provides a sheet‐like product for use as a food service package, a beverage service package, or any package suitable for the transport and/or storage of materials comprising oil, water, and/or grease comprising: [0139] (a) a substrate comprising lignocellulosic fibers, and having a first parallel large surface and a second parallel large surface, and [0140] (b) a coating structure comprising a barrier coating composition according to any of the foregoing compositions applied in at least one layer to at least one of the large surfaces of the substrate, [0141] wherein said sheet‐like product has [0142] (i) a KIT test value of 11‐12, or 12; and/or [0143] (ii) a Cobb 30 min value of less than 5 gsm. [0144] The present invention also provides a sheet‐like product for use as a food service package, a beverage service package, or any package suitable for the transport and/or storage of materials comprising oil, water, and/or grease comprising: [0145] (a) a substrate comprising lignocellulosic fibers, and having a first parallel large surface and a second parallel large surface, and
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0146] (b) a coating structure comprising a barrier coating composition prepared by a method according to any of the foregoing methods applied in at least one layer to at least one of the large surfaces of the substrate, [0147] wherein said sheet‐like product has [0148] (i) a KIT test value of 11‐12, or 12; and/or [0149] (ii) a Cobb 30 min value of less than 5 gsm. BRIEF DESCRIPTION OF THE DRAWINGS [0150] The invention will be described in more detail with reference to appended drawings, described in detail below. [0151] FIG 1 provides an exemplary bar graph of Cobb 30 min values vs coat weight in g/m2 (gsm) for barrier‐coated cupstock basesheets coated with double layer of barrier coating compositions according to Example 2. DETAILED DESCRIPTION OF THE INVENTION [0152] Before describing the invention, the following definitions are provided. Unless stated otherwise all terms are to be construed as they would be by a person skilled in the art. Definitions [0153] As used herein the singular forms “a”, “and”, and “the” include plural referents unless the context clearly dictates otherwise. [0154] The term “lignocellulosic substrate” refers to refers a paper and/or paperboard product formed from plant dry matter from any source, virgin or recycled, which may be coated, printed, and/or formed into a packaging product. For example, such substrates include paper products made from pulp, such as by methods comprising forming an aqueous cellulosic papermaking furnish, draining the furnish to form a sheet, and drying the sheet. The steps of forming the papermaking furnish, draining and drying may be carried out in any conventional manner generally known in the art. The substrates may contain polymeric strengthening agents, such as wet strength and dry strength agents. [0155] The terms “sheet‐like substrates” or sheet‐like products” refer to lignocellulosic substrates that may be formed into containers for use as a food service package, a beverage service package, or any package suitable for the transport and/or storage of materials comprising oil, water, and/or grease. Such sheet‐like substrates, when flat, have a “top side” planar surface and a “bottom side” planar surface, which are parallel to each other. Such “top side” and “bottom side” planar surface are also referred to as a “first parallel large surface” and a “second parallel large surface”. These surfaces may be coated with one or more layers, which form the basis of a barrier coating. [0156] The term “barrier coating” refers to a layer or multiple layers applied as a coating to paper and paperboard products that impart barrier properties that impart resistance to the permeation of oil, water, and grease, and/or vapors into and through the packaging, which passage if not prevented could cause undesirable leaks and staining. Barrier coatings are often applied to the one
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 or both surfaces of paper products to make such products useful for packaging food, beverage, raw materials, and other products. Barrier properties are useful when, for example, the packaged food product contains oil and/or grease, such as pizza or fried chicken. Such coatings should also provide the “substrate”, e.g., the paper or board material used to make the packaging material, with a smooth and uniform surface finish. In some instances, the barrier coating should have other properties, such as be glueable, printable, or heat sealable, in order to close the packaging. Barrier coatings may be applied as a single coating layer of any thickness, or as multiple coating layers, including double‐coatings, triple coatings, etc. The first layer applied may be referred to as the basecoat layer and the last layer may be referred to as the topcoat layer. Successive layers may be applied with or without drying and/or curing in between layer applications. [0157] The term “barrier coating composition” refers to any composition in liquid, emulsion, dispersion, solid, or gas form that is applied to the surface of a substrate to form a barrier coating. Typically, when in liquid, emulsion, or dispersion form, the barrier coating composition preferably has a viscosity that is amenable to application via conventional paper coaters, paper rolling‐coaters, or metering size press machines under room temperature conditions. [0158] The term “bio‐based” refers to any material that is (i) directly extracted from the biomass (natural materials) such as polysaccharides, proteins, and lipids, (ii) that is synthesized from the bio‐ derived materials, (iii) that is a biodegradable material, or (iv) that originates from sustainable and/or renewable resources. Such materials include monomers, polymers, lipids, or oils that are directly produced and extracted from microorganisms and then subjected to further processing techniques, such as hydrogenation, hydrolysis, esterification, fermentation, or enzymatic reactions. [0159] The term “bio‐based oil” refers to any oil derived or sourced, wholly or in part, from a plant or animal, including but not limited to, palm oil, castor oil, soybean oil, fish oil, tallow oil, a plant oil, an animal oil, a blend of plant and animal oils, or any combination thereof. [0160] The term “biowax” refers to any wax or waxy substance derived or sourced from a bio‐based oils. For example, biowaxes may be formed by partial or complete hydrogenation of bio‐based oils or mixtures of bio‐based oils to form biowax materials that have a higher melting point compared to the corresponding non‐hydrogenated bio‐based oil. [0161] The term “biowax emulsion” refers to an emulsion or mixture of immiscible liquids containing one or more biowaxes and water that have been emulsified into an inverse phase biowax emulsion. Biowax emulsions may also contain one or more rosin sizing agents, one or more surfactants, one or more microcrystalline or paraffinic waxes, or one or more long chain fatty acids, or any other material appropriate for formulation as a biowax‐based barrier composition for paper or board. The components of a biowax emulsion may be added together or separately and emulsification may be achieved by any convenient means of mixing, with or without heating. [0162] As used herein the term “substantially bio‐based barrier composition” means that the “barrier coating composition” defined as above is substantially or predominantly comprised of “bio‐ based” materials, e.g., the composition comprises at least 50, 60, 70, 80, 90, or 95% or more weight percent of bio‐based” materials as above defined, e.g., “biowaxes”, “bio‐based oils” as further above defined.
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0163] The term “microcrystalline wax” refers to a type of hydrocarbon wax produced by de‐oiling petrolatum, as part of the petroleum refining process, contains a relatively higher percentage of isoparaffinic (branched) hydrocarbons and naphthenic hydrocarbons compared to paraffin wax, and is characterized by the fineness of its crystals. Microcrystalline waxes generally consist of hydrocarbon waxes that predominantly comprise saturated acyclic and cyclic hydrocarbons or contains such structures as a major portion of the molecules therein. Naphthenic hydrocarbons are a type of organic compound of carbon and hydrogen that contains one or more saturated cyclic (ring) structures, or contains such structures as a major portion of the molecule. Other Naphthenic compounds are sometimes called naphthenes, cycloparaffins, or hydrogenated benzenes. [0164] The term “long chain fatty acid” refers to a carboxylic acid with an aliphatic chain having more than 12 carbons. Typically, the number of carbons in the aliphatic chain is denoted by C#, for example a 14 carbon aliphatic chain is referred to as a C14 fatty acid. Long chain fatty acids may be a single molecule or a mixture of fatty acids with various chain lengths. They may be linear or branched, saturated or unsaturated, or a combination thereof and may also contain mixtures of acids, anhydrides and esters. [0165] The term “carrier” refers a material into which a barrier coating material, such as a biowax emulsion, is dispersed or blended in order to prevent the coating material from penetrating into a paper or board substrate. A carrier allows for a barrier material or barrier coating composition to be applied as a barrier coating to a paper or board substrate without penetrating into the pores of the paper or board. A carrier also allows for a barrier coating to be applied one surface of a sheet‐like paper or board substrate without bleeding or soaking through to the opposite side. [0166] The term “polyacrylate carrier” refers to a dispersion of polyacrylates or polyacrylate copolymers containing acrylamide and/or other monomers into which is blended or dispersed various other components of a barrier coating material. [0167] The term “rheology modifier” refer to any substance that can alter the rheological properties (e.g., resistance to deformation and flow) of a material. They are added to formulations to increase or decrease viscosity and to control a finished the properties and characteristics of a liquid composition in a desired manner. [0168] The term “rosin sizing agent” refers to one or more alkali‐treated rosins used as a dry powder or emulsion to surface‐size paper products. Rosin size is often added to paper or board in the presence of aluminum species, and is used to increase barrier properties to water, moisture, and water vapor. [0169] The term “fortified rosin” refers to a major component of most rosin size products, produced by reacting the levopimeric acid component of rosin with maleic anhydride. Fortified rosin sizing agent is produced by the reaction with gum rosin and fumaric acid or maleic anhydride under suitable conditions. This is Diels‐alder adduct which acts as a very effective sizing agent. The Diels‐ Alder adduct contains extra carboxyl groups and produces more proficient sizing response than the unreacted resin acids. It is common that the rosin which is extract from tall oil is fortified with fumaric acid. In this case some of the abietic acid and related compounds are converted into tricarboxylic species.
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0170] The term “oil and grease resistance” or “OGR” refers to the ability to prevent wicking or flow of hydrophobic liquids into and across the surface of a paper or board. For example, higher OGR is achieved by rendering the surface of a paper or board substrate more lipophobic by adding a barrier coating. [0171] The term “water resistance” refers to the ability to prevent wicking or flow of aqueous liquids into and across the surface of a paper or board. For example, higher water resistance is achieved by rendering the surface of a paper or board substrate more hydrophobic by adding a barrier coating. [0172] The terms “dispersion” or “aqueous dispersion” generally refer to a heterogeneous mixture of a fluid (e.g., water) that contains solid particles, wherein the solid particles forms a phase separated mixture in which one substance of macroscopically or microscopically dispersed insoluble or soluble particles is suspended throughout another substance, typically a liquid substance. A dispersion has a dispersed phase (the suspended particles) and a continuous phase (the medium of suspension) that arise by phase separation. Macroscopic particles typically separate and settle quickly, while colloids typically do not completely settle or take a long time to settle completely into two separated layers. [0173] The term “liquid polymer” refers to a combination of at least one polymer and a liquid, typically an aqueous liquid. The polymer in a may be thoroughly dissolved or may be a partially dissolved suspension, dispersion, or slurry. An “aqueous polymer mixture” or “hydrated polymer composition” refers to a combination of at least one polymer and an aqueous liquid. When a dry polymer is combined with an aqueous liquid, the polymer is initially partially hydrated at the polymer–water interface. Polymers do not dissolve instantaneously in aqueous or non‐aqueous solvents. Dissolution is controlled by either the disentanglement of the polymer chains or by the diffusion of the chains through a boundary layer adjacent to the polymer–solvent interface. After thorough mixing, the polymer may become fully hydrated, at which point the wetting process is complete and the polymer may be either partially dissolved or fully dissolved, depending on the nature and composition of the polymer and solvent. [0174] The terms “polymer” or “polymeric additives” and similar terms are used in their ordinary sense as understood by one skilled in the art, and thus may be used herein to refer to or describe a large molecule (or group of such molecules) that may comprise recurring units. Polymers may be formed in various ways, including by polymerizing monomers and/or by chemically modifying one or more recurring units of a precursor polymer. Unless otherwise specified, a polymer may comprise a “homopolymer” that may comprise substantially identical recurring units that may be formed by, for example, polymerizing, a particular monomer. Unless otherwise specified, a polymer may also comprise a "copolymer” that may comprise two or more different recurring units that may be formed by, for example, copolymerizing, two or more different monomers, and/or by chemically modifying one or more recurring units of a precursor polymer. Unless otherwise specified, a polymer or copolymer may also comprise a “terpolymer” which generally refers to a polymer that comprises three or more different recurring units. Any one of the one or more polymers discussed herein may be used in any applicable process, for example, as a flocculant. [0175] As used herein, the phrase “inverse phase biowax emulsion” refers to a liquid composition of biowax, which is first formulated into an oil‐continuous phase containing a discontinuous aqueous
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 phase dispersed in the oil phase (e.g., hydrophobic liquid), to which is then added an aqueous solution (e.g., water) so that the biowax composition becomes a substantially aqueous‐continuous phase and the hydrophobic liquid phase becomes a dispersed, discontinuous phase. The inversion point can be characterized as the point at which the viscosity of the inverted polymer solution has substantially reached its maximum under a given set of conditions. In practice, this may be determined for example by measuring viscosity of the composition periodically over time and when three consecutive measurements are within the standard of error for the measurement, then the solution is considered inverted. In an embodiment of the invention, an inverse phase biowax emulsion is formed by combining biowax, rosin size, surfactants, microcrystalline or paraffinic waxes, long chain fatty acid, and organic base and heating to 90‐95 °C to form an oil‐continuous phase. To this is added an amount of hot water. The mixture was emulsified at 75‐98 °C and then homogenized and cooled to form the inverse phase biowax emulsion having a substantially aqueous‐continuous phase. [0176] As used herein, the term "polyacrylate" refers to a homopolymer of acrylate monomers, a copolymer of acrylate and acrylamide monomers, and also encompasses acrylamide polymers which are partially or completely hydrolyzed following polymerization. [0177] As used herein the term "polyacrylate copolymer" refers to a polymer comprising an acrylate monomer and one or more comonomers. The comonomer may be anionic, cationic or non‐ionic. In certain embodiments, the comonomer is hydrophilic. The acrylamide copolymer may be unmodified or chemically modified. Representative, non‐limiting co‐monomers include acrylic acid, vinyl acetate, vinyl alcohol and/or other unsaturated vinyl monomers. In certain embodiments, the acrylamide‐ containing copolymer comprises acrylic acid comonomers. [0178] As used herein the term "hydrolyzed acrylamide” or “partially hydrolyzed acrylamide” refers to an acrylamide containing polymer which has been partially reacted with water to form acrylate or acrylic acid side chains. [0179] As used herein, "emulsion polymer" generally refers to inverse emulsions (water‐in‐oil) in which water droplets containing the polymer are suspended in an oil phase, also termed a hydrophobic phase. [0180] As used herein, "nonionic monomer” refers to a monomer which possesses a net charge of zero in aqueous solution. Non‐limiting examples of nonionic monomers include, acrylamide, N‐ alkylacrylamides, N,N‐dialkylacrylamides, methacrylamide, N‐vinylmethylacetamide or formamide, vinyl acetate, vinyl pyrrolidone, alkyl methacrylates, acrylonitrile, N‐vinylpyrrolidone other acrylic (or other ethylenically unsaturated) ester or other water insoluble vinyl monomers such as styrene or acrylonitrile. [0181] As used herein, "anionic monomer" refers to a monomer which possesses a negative charge in aqueous solution. Non‐limiting representative anionic monomers include acrylic acid, sodium acrylate, ammonium acrylate, methacrylic acid, 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS), vinyl sulfonic acid, styrene sulfonic acid, maleic acid, sulfopropyl acrylate or methacrylate or other water‐soluble forms of these or other polymerizable carboxylic or sulphonic acids, sulfomethylated acrylamide, ally sulfonate, itaconic acid, acrylamidomethylbutanoic acid, fumaric acid, vinylphosphonic acid, allylphosphonic acid, phosphonomethylated acrylamide, methacrylate,
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 itaconate, 2‐acrylamido 2‐methyl propane sulphonate, sulfoalkyl(meth)acrylic acids, sulfonated styrenes, unsaturated dicarboxylic acids, sulfoalkyl(meth)acrylamides, vinyl acetate, n‐ vinylformamide, n‐vinylacetamide, n‐vinylcaprolactam, n‐vinylimidazole, n‐vinylpyridine, n‐ vinylpyrolidone, acrylamidopropyltrimonium chloride, salts of said acids and the like, or another anionic ethylenically unsaturated compound. [0182] As used herein, “micro‐fibrillated cellulose” and “MFC” refer to a form of cellulose (i.e., polymer made of repeating units of glucose) obtained through a fibrillation process of cellulose fibers. Using mechanical shearing, the cellulose fibers are separated into a three dimensional network of microfibrils having a large surface area. The obtained fibrils are much smaller in diameter compared to the original fibers, and can form a network or a web‐like structure. MFC may be obtained from any convenience cellulose source, including but not limited to parenchymal (non‐ wood) cellulose, sugar beet cellulose, wood‐based cellulose, and preferably from any plant or vegetable based cellulose source. Description of the Invention [0183] The present invention relates to compositions and methods for forming substantially bio‐ based barrier coatings, e.g., for application on paper and board substrates, e.g., those comprised of recycled fiber materials. The inventors have provided novel compositions and methods for forming substantially bio‐based barrier coatings for paper and board. The invention provides biowax‐based barrier compositions that can form barrier layers for enhancing oil, grease, and water resistance and can be applied without causing damage to the substrate and which deliver a sustainable bio‐based barrier coating solution to potentially replace or minimize the need for petroleum based coatings. [0184] A packaging material requires sufficient barrier properties against water, water vapor, gases/air and grease/oils depending on the end use application, with the aim to protect the material from ambient environment or prevent the loss of flavors, fragrance, and moisture from food products. Any single material layer used in the packaging is able to provide a barrier against water, or water vapor, or gas, or grease, or combinations of maximum two or three properties, but it rarely provides full protection against all four properties. Application of multiple barrier layers is often necessary. [0185] Herein, biowax emulsions, polyacrylate dispersions, and other additives are employed to form barrier coating compositions having long shelf life, high solids content, high bio‐based content, and rheological properties that facilitate application as barrier coatings using conventional methods at room temperature. Barrier coating compositions comprising a biowax emulsion dispersed into one or more polyacrylate carriers with one or more rheology modifiers and auxiliary additives (e.g., clay, MCC, and the like), when used to coat paper and/or board achieved excellent oil and water barrier properties including (i) greater than 50% bio‐content (renewable raw material) in multiple coating layers, (ii) Cobb value (30 min) of two‐layer coated sheets < 5 g/m2; and (iii) KIT value = 12, which are ideal for many packaging material applications. [0186] In exemplary embodiments, one or more surfactants are added to the barrier coating composition which are capable of stabilizing water‐in‐oil emulsions. Surfactants, among other things, lower the interfacial tension between the water and the water‐immiscible liquid in the liquid polymer composition, so as to facilitate the formation of a water‐in‐oil polymer emulsion. Exemplary
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 surfactants include, but are not limited to, sorbitan esters, in particular sorbitan monoesters with C12‐C18‐groups such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan esters with more than one ester group such as sorbitan tristearate, sorbitan trioleate, ethoxylated fatty alcohols with 1 to 4 ethyleneoxy groups, e.g. polyoxyethylene ( 4) dodecylether ether, polyoxyethylene (2) hexadecyl ether, or polyoxyethylene (2) oleyl ether. Other exemplary non‐limiting surfactants include the sorbitan esters, phthalic esters, fatty acid glycerides, glycerine esters, as well as the ethoxylated versions of the above. Examples of such compounds include sorbitan monooleate, the reaction product of oleic acid with isopropanolamide, hexadecyl sodium phthalate, decyl sodium phthalate, sorbitan stearate, ricinoleic acid, hydrogenated ricinoleic acid, glyceride monoester of lauric acid, glyceride monoester of stearic acid, glycerol diester of oleic acid, glycerol triester of 12‐hydroxystearic acid, glycerol triester of ricinoleic acid, and the ethoxylated versions thereof containing 1 to 10 moles of ethylene oxide per mole of the basic emulsifier. Examples of emulsifying surfactants also include modified polyester surfactants, anhydride substituted ethylene copolymers, N,N‐dialkanol substituted fatty amides, and tallow amine ethoxylates. Furthermore, one or more surfactants may comprise nonionic surfactants, anionic surfactants, or a combination thereof, wherein (i) said nonionic surfactants are selected from ethoxylated alcohols, including but not limited to, TERGITOL™ 15‐S‐40, ethoxylated sorbitan esters, sorbitan esters, glycerol esters, including but not limited to, glycerol monostearate (GMS), and any combination thereof, and (ii) said anionic surfactants may be selected from, fatty alcohol ether sulfates, alkyl ether sulfates, special soaps, including but not limited to, anionic long chain fatty acids and Hystrene 8522 (C22 FA), and any combination thereof; [0187] In exemplary embodiments, auxiliary additives such as clay , nano‐clay, and/or microcrystalline cellulose (MCC) are added to barrier coating compositions and applied the basecoat to increase the natural material content in barrier coating. Clay at a low dosage range also has the ability of stabilizing final barrier coating dispersions. Previous studies have demonstrated the effectiveness of nano‐clay in improving barrier performance through the tortuosity effect. Hi aspect ratio clays (e.g., aspect ratio =5000) give a good barrier at low filler levels. Great barrier properties can also be achieved by combined use of nano‐clay and MCC in coating formulations. Microcrystalline cellulose (MCC) is commercially used as a texturizer, an anticaking agent, a fat substitute, an emulsifier and an extender in food production. MCC dry powder compacts well and has high binding capability. The auxiliary additives of MCC and nano‐clay at low dosage levels (total content up to 10 wt%) further increase the oil resistance of biowax. [0188] It has been surprisingly found that the addition of clay greatly improved the water barrier performance of the biowax coating and MCC used in the basecoat further increased the water barrier performance. This provided to be a surprising method to improve both bio‐content and the barrier properties of paper through the optimization of basecoat formulations. Barrier Coating Compositions and Methods [0189] In one aspect, the present invention provides a barrier coating composition for paper or board, said barrier coating composition comprising: [0190] (a) one or more biowax emulsions; (b) one or more polyacrylate carriers; and (c) optionally, one or more auxiliary additives.
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0191] In some embodiments the barrier coating composition further comprises one or more rheology modifiers. [0192] In another aspect, the present invention provides a barrier coating composition for paper or board, said barrier coating composition comprising: [0193] (a) one or more biowax emulsions comprising a pre‐formed inverse phase biowax emulsion comprising at least one or more biowaxes, water, one or more rosin sizing agents, one or more surfactants, one or more microcrystalline or paraffinic waxes, and optionally, one or more long chain fatty acids, wherein the inverse phase biowax emulsion is pre‐ formulated separately prior to addition to the barrier coating composition; (b) one or more polyacrylate carriers; and (c) optionally, one or more auxiliary additives. [0194] In another aspect, the present invention provides a barrier coating composition for paper or board, said barrier coating composition comprising: (a) one or more biowax emulsions; (b) one or more polyacrylate carriers; and (c) optionally, one or more auxiliary additives, wherein said one or more biowax emulsions comprise: [0195] (i) one or more biowaxes optionally comprising palm oil wax, castor oil wax, soybean oil wax, fish oil wax, tallow oil wax, a plant oil wax, an animal oil wax, a blend of plant and animal oil waxes, or any combination thereof; [0196] (ii) one or more rosin sizing agents optionally comprising fortified rosins, esterified rosins, rosin waxes, resin acid derivatives, gum rosins, wood rosins, tall oil rosins, rosin pastes, rosin‐based dispersants, or any combination thereof; [0197] (iii) one or more surfactants optionally comprising one or more nonionic surfactants, one or more anionic surfactants, or a combination thereof, wherein (a) said one or more nonionic surfactants comprise ethoxylated alcohols, including but not limited to, secondary alcohol ethoxylates, ethoxylated sorbitan esters, sorbitan esters, glycerol esters, including but not limited to, glycerol monostearate (GMS), and any combination thereof, and (b) said one or more anionic surfactants comprise fatty alcohol ether sulfates, alkyl ether sulfates, special soaps, including but not limited to, anionic long chain fatty acids, and any combination thereof; [0198] (iv) one or more microcrystalline or paraffinic waxes optionally comprising saturated hydrocarbon waxes, paraffinic hydrocarbon waxes, isoparaffinic hydrocarbon waxes, naphthenic hydrocarbon waxes, and a mixture thereof, having a congealing point of 50‐110 °C, 65‐100 °C, 70‐ 90 °C, or 75‐85 °C; and [0199] (v) optionally, one or more long chain fatty acids having a carbon chain length ranging from C18‐C30, C20‐C30, C22‐C30, or C24‐C30. [0200] Biowax Emulsions [0201] In some embodiments the one or more biowax emulsions comprise at least one or more biowaxes, one or more rosin sizing agents, one or more surfactants, one or more microcrystalline or paraffinic waxes, and optionally one or more long chain fatty acids. [0202] In some embodiments the one or more biowax emulsions comprise: (a) one or more biowaxes selected from the group consisting of palm oil wax, castor oil wax, soybean oil wax, fish oil
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 wax, tallow oil wax, a plant oil wax, an animal oil wax, a blend of plant and animal oil waxes, or any combination thereof; (b) one or more rosin sizing agents, including but not limited to, fortified rosins, esterified rosins, rosin waxes, resin acid derivatives, gum rosins, wood rosins, tall oil rosins, rosin pastes, rosin‐based dispersants, or any combination thereof; (c) one or more surfactants comprising nonionic surfactants, anionic surfactants, or a combination thereof, wherein (i) said nonionic surfactants are selected from ethoxylated alcohols, including but not limited to, secondary alcohol ethoxylates, ethoxylated sorbitan esters, sorbitan esters, glycerol esters, including but not limited to, glycerol monostearate (GMS), and any combination thereof, and (ii) said anionic surfactants are selected from, fatty alcohol ether sulfates, alkyl ether sulfates, special soaps, including but not limited to, anionic long chain fatty acids, and any combination thereof; (d) one or more microcrystalline or paraffinic waxes, including but not limited to saturated hydrocarbon waxes, paraffinic hydrocarbon waxes, isoparaffinic hydrocarbon waxes, naphthenic hydrocarbon waxes, and a mixture thereof, having a congealing point of 50‐110 °C, 65‐100 °C, 70‐90 °C, or 75‐85 °C; and (e) optionally, one or more long chain fatty acids having a carbon chain length ranging from C18‐C30, C20‐C30, C22‐C30, or C24‐C30. [0203] In some embodiments the one or more biowax emulsions comprise a W/O emulsion (water‐ in‐oil), an invert emulsion (O/W, oil‐in‐water), a W/O emulsion that has been subjected to phase inversion to form an invert emulsion, or an invert emulsion that has been subjected to phase inversion to form a W/O emulsion, or an inverse phase biowax emulsion. [0204] In some embodiments the one or more biowax emulsions comprise a pre‐formed inverse phase biowax emulsion, which is pre‐ formulated by (a) combining at least one or more biowaxes, one or more rosin sizing agents, one or more surfactants, one or more microcrystalline or paraffinic waxes, and optionally one or more long chain fatty acids in a reactor and heating to a temperature ranging from 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 (e.g., 70‐99 °C, 75‐98 °C, or 85‐95 °C water) to said oil‐phase; (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; and (f) optionally adding a biocide. [0205] In some embodiments, the one or more biowax emulsions comprise an inverse phase biowax emulsion, which is pre‐formulated separately prior to addition to the barrier coating composition by dispersing said inverse phase biowax emulsion into said one or more polyacrylate carriers, said optional rheology modifiers, and/or said optional auxiliary additives. [0206] In some embodiments, the one or more biowax emulsions comprise a pre‐formed inverse phase biowax emulsion, which is pre‐formulated separately prior to addition to the barrier coating composition, preferably by dispersing said inverse phase biowax emulsion into said one or more polyacrylate carriers, prior to, during, or after addition of the optional rheology modifiers and/or optional auxiliary additives. [0207] In some preferred embodiments, the one or more biowax emulsions comprise a pre‐formed inverse phase biowax emulsion, which is pre‐formulated separately prior to addition to the barrier coating composition, preferably by dispersing said inverse phase biowax emulsion into said one or
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 more polyacrylate carriers, prior to addition of the optional rheology modifiers and/or optional auxiliary additives. [0208] In some embodiments, the pre‐formed inverse phase biowax emulsion is pre‐formulated separately and comprises a total solids content ranging from 50‐80 wt%, 50‐70 wt%, 50‐60 wt%, or 55‐57 wt% and further wherein ≥ 50 wt% of said total solids content is bio‐based. [0209] In some embodiments, the pre‐formed inverse phase biowax emulsion is pre‐formulated separately and then added to (i) the one or more polyacrylate carriers, (ii) optionally the one or more auxiliary additives, and (iii) optionally the one or more rheology modifiers, thereby forming a barrier coating composition having improved solids content, improved bio‐based solids content (e.g., 40‐60 wt%, 45‐60 wt%, 50‐60 wt%, or 55‐60 wt%), improved particle size, improved bulk viscosity, and/or improved stability of the final barrier coating composition compared to the same barrier coating composition formed without pre‐formulating the one or more biowaxes as an inverse phase biowax emulsion. [0210] In some exemplary embodiments according to any of the foregoing said one or more biowax emulsions comprise an inverse phase biowax emulsion formed by: [0211] (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 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 (e.g., 70‐99 °C, 75‐98 °C, or 85‐95 °C water) to said oil‐phase; (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 by means of an ice‐water bath, a cooling jacket, or a cooling core; and (f) optionally adding a biocide. [0212] In some exemplary embodiments said one or more biowaxes: [0213] (a) comprise one or more hydrogenated bio‐based oils including, but not limited to, palm oil, castor oil, soybean oil, fish oil, tallow oil, a plant oil, an animal oil, a blend of plant and animal oils, or any combination thereof, and wherein each of said hydrogenated bio‐based oils has a higher melting point compared to the corresponding non‐hydrogenated bio‐based oil; and (b) have a melting point of 55‐98 °C, 60‐95 °C, 65‐90 °C, 70‐85 °C, or 75‐80 °C. [0214] In some exemplary embodiments according to any of the foregoing, in said one or more biowax emulsions: [0215] (a) said one or more biowaxes comprises castor oil wax; (b) said one or more rosin sizing agents comprises fortified rosin size; (c) said nonionic surfactants comprise secondary alcohol ethoxylates, glycerol monostearate (GMS), or a combination thereof and said anionic surfactants comprise anionic long chain fatty acids, or a combination thereof; (d) said one or more microcrystalline or paraffinic waxes has a congealing point of 70‐90 °C; and (e) said one or more long chain fatty acids has a carbon chain length ranging from C22‐C30. [0216] In some exemplary embodiments according to any of the foregoing said one or more biowax emulsions comprise:
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0217] (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%. [0218] In some exemplary embodiments according to any of the foregoing said one or more biowax emulsions, in final form: [0219] (a) comprise a total solids content ranging from 50‐80 wt%, 50‐70 wt%, 50‐60 wt%, or 55‐57 wt% and further wherein ≥ 50 wt% of said total solids content is bio‐based; and/or (b) have a final bulk viscosity ranging from 1400‐1800 cPs, 1500‐1700 cPs, 1550‐1650 cPs, or 1590‐1610 cPs. [0220] Polyacrylate Carriers [0221] In some exemplary embodiments according to any of the foregoing 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%. [0222] In some exemplary embodiments said barrier coating composition comprises said one or more polyacrylate carriers in an amount ranging from 20‐80 wt%, 30‐70 wt%, or 40‐60 wt%. [0223] In some exemplary embodiments said one or more biowax emulsions, optional rheology modifiers, and optional auxiliary additives are dispersed, together or separately in any order, directly into said one or more polyacrylate carriers to form the barrier coating composition. [0224] Rheology Modifiers [0225] In some exemplary embodiments according to any of the foregoing 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. [0226] In preferred embodiments said one or more rheology modifiers comprise pre‐hydrated cellulose gums and xanthan gums. [0227] In some exemplary embodiments said barrier coating composition comprises 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. [0228] In some exemplary embodiments said one or more rheology modifiers are dispersed directly into the barrier coating composition prior to, during, or after addition of the biowax emulsions, polyacrylate carriers, and/or auxiliary additives. In some exemplary embodiments said one or more
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 rheology modifiers are dispersed directly into said one or more polyacrylate carriers separately or together with the biowax emulsions and/or auxiliary additives. [0229] Auxiliary Additives [0230] In some exemplary embodiments according to any of the foregoing 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; [0231] In preferred embodiments said one or more auxiliary additives comprises clay, nano‐clay, microcrystalline cellulose (MCC), or a combination thereof. [0232] In some exemplary embodiments according to any of the foregoing, in said one or more auxiliary additives: (a) said clay and/or nano‐clay is formulated as an aqueous slurry having total solids of 60‐80 wt%, 65‐75 wt%, or 68‐72 wt% prior to being dispersed into said barrier coating composition; (b) said cellulose nanocrystals (CNC) is formulated as an aqueous slurry or a spray‐dried powder prior to being dispersed into said barrier coating composition, and is optionally produced by acid hydrolysis of cellulose; (c) said micro‐fibrillated cellulose (MFC) (i) has an average particle length ranging from 20‐200 µm, 50‐200 µm, 100‐200 µm, or 150‐200 µm, (ii) has an average particle width ranging from 0.1‐1 µm, 0.2‐1 µm, 0.4‐1 µm, or 0.6‐1 µm, and (iii) is formulated as an aqueous solution having a dry content of 10‐30 wt%, 15‐25 wt%, or 18‐22 wt% prior to formulation with said barrier coating composition; and (d) said microcrystalline cellulose (MCC) (i) has an average particle size ranging from 1‐8 µm, 2‐7 µm, 3‐6 µm, or 4‐5 µm, and (ii) is formulated as an aqueous slurry or a spray‐dried powder prior to being dispersed into said barrier coating composition. [0233] In some exemplary embodiments said one or more auxiliary additives are dispersed directly into the barrier coating composition prior to, during, or after addition of the biowax emulsions, polyacrylate carriers, and/or rheology modifiers. In some exemplary embodiments said one or more auxiliary additives are dispersed directly into said one or more polyacrylate carriers separately or together with the biowax emulsions and/or rheology modifiers. [0234] In some exemplary embodiments according to any of the foregoing said barrier coating composition comprises: [0235] (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. [0236] In some exemplary embodiments according to any of the foregoing 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
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 additives into said one or more polyacrylate carriers with mechanical mixing to form said stable dispersion; wherein said barrier coating composition, in final form: [0237] (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 2.5‐3 µm; (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). Barrier Coatings [0238] In some exemplary embodiments according to any of the foregoing the barrier coating composition, 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: [0239] (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; [0240] (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; [0241] (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; [0242] (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; [0243] (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 [0244] (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%.
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 Methods for Preparing Barrier Coating Compositions [0245] In another aspect, the present invention provides a method for preparing a barrier coating composition for paper or board, optionally according to any of the foregoing compositions, the method comprising: [0246] (a) forming at least one biowax emulsion, preferably as an inverse phase emulsion; [0247] (b) forming or providing one or more polyacrylate carriers; [0248] (c) dispersing said at least one biowax emulsion into said one or more polyacrylate carriers; [0249] (d) optionally, dispersing one or more rheology modifiers into said one or more polyacrylate carriers; and [0250] (e) optionally, dispersing one or more auxiliary additives into said one or more polyacrylate carriers; [0251] wherein steps (c)‐(e) are effected together or separately. [0252] In another aspect, the present invention provides a method for preparing a barrier coating composition for paper or board, optionally according to any of the foregoing compositions, the method comprising: [0253] (a) forming at least one biowax emulsion, preferably as an inverse phase biowax emulsion; [0254] (b) dispersing said inverse phase biowax emulsion into one or more polyacrylate carriers; [0255] (c) optionally, dispersing one or more rheology modifiers into said one or more polyacrylate carriers; and [0256] (d) optionally, dispersing one or more auxiliary additives into said one or more polyacrylate carriers. [0257] wherein step (a) is performed prior to step (b) and steps (b)‐(d) are effected together, or separately in the order of (b), (c), then (d), or optionally in any order. [0258] In some exemplary embodiments of the method said at least one biowax emulsion comprises: [0259] (a) one or more biowaxes selected from the group consisting of palm oil wax, castor oil wax, soybean oil wax, fish oil wax, tallow oil wax, a plant oil wax, an animal oil wax, a blend of plant and animal oil waxes, or any combination thereof, wherein said one or more biowaxes (i) comprises one or more hydrogenated bio‐based oils including, but not limited to, palm oil, castor oil, soybean oil, fish oil, tallow oil, a plant oil, an animal oil, a blend of plant and animal oils, or any combination thereof, wherein each of said hydrogenated bio‐based oils has a higher melting point compared to the corresponding non‐hydrogenated bio‐based oil and (ii) has a melting point of 55‐98 °C, 60‐95 °C, 65‐90 °C, 70‐85 °C, or 75‐80 °C; (b) one or more rosin sizing agents, including but not limited to, fortified rosins, esterified rosins, rosin waxes, resin acid derivatives, gum rosins, wood rosins, tall oil rosins, rosin pastes, rosin‐based dispersants, or any combination thereof; (c) one or more surfactants comprising nonionic surfactants, anionic surfactants, or a combination thereof, wherein (i) said nonionic surfactants are selected from ethoxylated alcohols, including but not limited to, secondary alcohol ethoxylates, ethoxylated sorbitan esters, sorbitan esters, glycerol esters, including
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 but not limited to, glycerol monostearate (GMS), and any combination thereof, and (ii) said anionic surfactants are selected from, fatty alcohol ether sulfates, alkyl ether sulfates, special soaps, including but not limited to, anionic long chain fatty acids, and any combination thereof; (d) one or more microcrystalline or paraffinic waxes, including but not limited to saturated hydrocarbon waxes, paraffinic hydrocarbon waxes, isoparaffinic hydrocarbon waxes, naphthenic hydrocarbon waxes, and a mixture thereof, having a congealing point of 50‐110 °C, 65‐100 °C, 70‐90 °C, or 75‐85 °C; and (e) optionally, one or more long chain fatty acids having a carbon chain length ranging from C18‐C30, C20‐C30, C22‐C30, or C24‐C30. [0260] In some exemplary embodiments of the method said at least one biowax emulsion comprises: [0261] (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%, [0262] In some exemplary embodiments of the method said at least one biowax emulsion comprises an inverse phase biowax emulsion, formed by: [0263] (i) 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 to 70‐99 °C, 75‐98 °C, 85‐95 °C, or 90‐95 °C to form an oil‐phase; (ii) adding an amount of hot water (e.g., 70‐99 °C, 75‐98 °C, or 85‐95 °C water) to said oil‐phase; (iii) 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; (iv) homogenizing; (v) cooling the resulting inverse phase biowax emulsion to a temperature ranging from 10‐35 °C, 15‐30 °C, or 20‐25 °C, optionally by means of an ice‐water bath, a cooling jacket, or a cooling core; and (vi) optionally adding a biocide. [0264] In some exemplary embodiments of the method said at least one biowax emulsion, in final form: [0265] (a) comprises a total solids content ranging from 50‐80 wt%, 50‐70 wt%, 50‐60 wt%, or 55‐57 wt% and further wherein ≥ 50 wt% of said total solids content is bio‐based; and (b) has a final bulk viscosity ranging from 1400‐1800 cPs, 1500‐1700 cPs, 1550‐1650 cPs, or 1590‐1610 cPs. [0266] In some exemplary embodiments of the method: [0267] (a) said one or more polyacrylate carriers comprises 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 comprises 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
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 molecular weight ranging from 1000‐100,000 Da, 2000‐80,000 Da, or 10,000‐50,000 Da, or a combination thereof; and (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, wherein [0268] (i) said clay and/or nano‐clay is formulated as an aqueous slurry having total solids of 60‐80 wt%, 65‐75 wt%, or 68‐72 wt% prior to being dispersed into said barrier coating composition using a mechanical mixing device; [0269] (ii) said cellulose nanocrystals (CNC) is formulated as an aqueous slurry or a spray‐dried powder prior to being dispersed into said barrier coating composition using a mechanical mixing device, and is optionally produced by acid hydrolysis of cellulose; [0270] (iii) said micro‐fibrillated cellulose (MFC) (i) has an average particle length ranging from 20‐ 200 µm, 50‐200 µm, 100‐200 µm, or 150‐200 µm, (ii) has an average particle width ranging from 0.1‐ 1 µm, 0.2‐1 µm, 0.4‐1 µm, or 0.6‐1 µm, and (iii) is formulated as an aqueous solution having a dry content of 10‐30 wt%, 15‐25 wt%, or 18‐22 wt% prior to formulation with said barrier coating composition; and [0271] (iv) said microcrystalline cellulose (MCC) (i) has an average particle size ranging from 1‐8 µm, 2‐7 µm, 3‐6 µm, or 4‐5 µm, and (ii) is formulated as an aqueous slurry or a spray‐dried powder prior to being dispersed into said barrier coating composition using a mechanical mixing device. [0272] In some exemplary embodiments of the method said barrier coating composition comprises: [0273] (a) said at least one biowax emulsion 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) optionally, 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, [0274] wherein said at least one biowax emulsion, said one or more rheology modifiers, and optionally said one or more auxiliary additives are dispersed, separately or together, into said one or more polyacrylate carriers with mechanical mixing to form said barrier coating composition, wherein, in final form, said barrier coating composition (i) comprises a total solids content ranging from 30‐70 wt%, 40‐60 wt%, 45‐55 wt%, or 48‐52 wt%; (ii) 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; (iii) has a particle size ranging from 0.2‐5 µm, 1‐4 µm, 2‐3 µm, or 2.5‐3 µm; (iv) has a bulk viscosity ranging from 40‐800 cPs, 100‐700 cPs, 150‐650 cPs, or 200‐400 cPs; (v) comprises a stable dispersion having a stability greater than 3 months at 25 °C, wherein stability is determined by said barrier coating composition maintaining a 3 month aged viscosity within ±50%, ±40%, ±30%, or ±20% of said bulk viscosity in (iv); or (vi) any combination of one, two, three, four or all five of (a) to (e).
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0275] In some exemplary embodiments of the method said barrier coating composition is 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, and wherein application of said barrier coating composition results in one or more of the following: [0276] (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; [0277] (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; [0278] (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; [0279] (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; [0280] (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 [0281] (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%. [0282] In another aspect, the present invention also provides a sheet‐like product for use as a food service package, a beverage service package, or any package suitable for the transport and/or storage of materials comprising oil, water, and/or grease comprising: [0283] (a) a substrate comprising lignocellulosic fibers, and having a first parallel large surface and a second parallel large surface, and (b) a coating structure comprising a barrier coating composition according to any of the foregoing compositions applied in at least one layer to at least one of the large surfaces of the substrate, wherein said sheet‐like product has (i) a KIT test value of 11‐12, or 12; and/or (ii) a Cobb 30 min value of less than 5 gsm. [0284] The present invention also provides a sheet‐like product for use as a food service package, a beverage service package, or any package suitable for the transport and/or storage of materials comprising oil, water, and/or grease comprising:
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0285] (a) a substrate comprising lignocellulosic fibers, and having a first parallel large surface and a second parallel large surface, and (b) a coating structure comprising a barrier coating composition prepared by a method according to any of the foregoing methods applied in at least one layer to at least one of the large surfaces of the substrate, wherein said sheet‐like product has (i) a KIT test value of 11‐12, or 12; and/or (ii) a Cobb 30 min value of less than 5 gsm. [0286] The methods and compositions illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein and/or any element specifically disclosed herein. Exemplary embodiments of the invention and its advantages are further disclosed in the following examples. EXAMPLES [0287] The examples provided herein are for illustrative purposes so that the invention may be more fully understood. These examples should not be construed as limiting the invention in any way. Example 1: Preparation of barrier coating compositions [0288] Barrier coating compositions were prepared to be evaluated as coatings for paper or paperboard. [0289] BIOWAX EMULSIONS [0290] Table 1: Biowax Emulsions. Biowax Biowax Rosin Size Surfactants Microcrystalline Long Chain Fatty Additive Emulsion (wt%) (wt%) (wt%) Wax (wt%) Acids (wt%) (wt%) %)
ether sulfates, alkyl ether sulfates, special soaps [0292] High solid biowax emulsions (total solids, TS over 50%) were prepared from castor wax, rosin size, nonionic and anionic surfactants, microcrystalline wax, long chain fatty acids, and optional additives according to Table 1. The components were blended to form an inverse phase emulsion and then cooled using a quick cooling process. [0293] Inverse phase emulsions were formed by combining components according to Table 1 in a reactor and heating to a temperature ranging from 90‐95 °C to form an oil‐phase, to which was added an amount of hot water. The mixture was emulsified at 75‐98 °C for 0.5‐4 h, homogenized, and then cooled to a temperature ranging from 15‐25 °C. Quick cooling was achieved by cooling the resulting inverse phase emulsion by means of an ice‐water bath, a cooling jacket, or a cooling core to a temperature ranging from 15‐25 °C. A biocide was then added. [0294] The final biowax emulsion, BE1, yielded a bulk viscosity of 1600 cPs and total solids of 56%.
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0295] BARRIER COATING COMPOSITIONS (BCC) [0296] Table 2: Barrier coating compositions (BCC). Barrier Coating Composition BE1 (dry wt%) Polyacrylate* Rheology Modifier** (dry wt%) (dry wt%) Clay (dry wt%) 1N H2SO4 (wt%)
[0298] pre‐hydrated Ticaloid 5415 [0299] Barrier coating compositions (BCC1‐2) were prepared by combining high solids biowax emulsion (BE1), a rheology modifier, and optional auxiliary additives into a polyacrylate carrier, according to Table 2. [0300] The polyacrylate carrier is an aqueous dispersion of polyacrylate (50% total dry solids), made from 100% fossil‐based raw materials, which acts as a paper barrier coating with both oil and water barrier properties, but poor blocking properties, and was used as Control 1. [0301] The inventive barrier coating compositions were formed by directly dispersing components according to Table 2 into the polyacrylate carrier to form stable biowax barrier coating dispersions with final bulk viscosities generally in the range of 80‐600 cPs. [0302] Where indicated, clay at a low dosage range was added to stabilize final barrier coating dispersions. Clay was formulated as an aqueous slurry having total solids of 70 wt% prior to being dispersed into the barrier coating composition. [0303] Where indicated, microcrystalline cellulose (MCC) has the ability to provide barrier enhancing properties. MCC having an average particle size ranging from 3‐6 µm was added as a spray‐dried powder and was dispersed into the polyacrylate carrier. [0304] The bulk viscosities of final biowax barrier coating dispersion were controlled in the range of 100 to 600 cPs by varying the dosage of a bio‐based rheology modifier, pre‐hydrated Ticaloid 5415. Final viscosities were selected to be suitable for use on either conventional paper coaters or metering size press machines under room temperature conditions. [0305] Stability testing was performed by aging a biowax barrier coating dispersion with the initial bulk viscosity of 540 cPs for 3 months at 25 °C. The 3 months aged viscosity increased to 720 cPs, which amounts to a 33% increase, indicating a high degree of stability at room temperature. [0306] Properties of barrier coating compositions (BCC) in final form are listed in Table 3.
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0307] Table 3: Properties of barrier coating compositions (BCC). Barrier Coating Total Solids Bio‐content, % of Bulk Viscosity, Particle Size, Composition % total solids cPs μm Stability at 25 °C o a
months), high total solids (>50%) and a high percentage of solids from bio‐based content (i.e., sustainable and renewable sources). Bulk viscosities were suitable for use on either conventional paper coaters or metering size press machines under room temperature conditions. Example 2: Evaluation of barrier coatings for recycled linerboard sheets [0309] Substrates for barrier coatings were non‐surface sized, low internal sized, 100% recycled linerboard base‐sheets. [0310] Barrier coating compositions (control 1, BCC 1, and BCC2) were applied at a single coat weight to the recycled linerboard base‐sheet by roller‐coating, followed by oven curing at 110 °C for 90 secs. A double‐coating (same barrier coating composition for topcoat and basecoat) of each barrier coating composition was applied to a single side of the recycled linerboard base‐sheet. Oven curing was performed after each coat application. [0311] Two barrier‐coated paper tests were performed to evaluate the barrier coatings. Cobb 5 min and Cobb 30 min tests were performed to determine the mass of water that can be absorbed by the surface of paper or board, in g/m2 (gsm) over a given time (e.g., 5 min or 30 min). A Kit test was performed to measure the oil and grease resistance (OGR) level of the sheet. Kit test values range from 1‐12, with 1 indicating no OGR barrier and 12 indicating very good OGR. [0312] Properties of the uncoated 100% recycled linerboard base‐sheet, including uncoated Kit test and Cobb 5 min test results are listed in Table 4. [0313] Table 4: Properties of 100% recycled linerboard base‐sheet. Grammage (g/m2) Gurley porosity (10 ml air), Sec HST, Sec KIT‐value Cobb 5 min (g/m2)
n Table 5.
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0315] Table 5: Properties of barrier‐coated 100% recycled linerboard base‐sheet. Barrier Coating Total Coat Cobb 30 Composition Weight (gsm) KIT Value min value, gsm Comments al al s
ter resistance properties compared to the polyacrylate dispersion control. BCC1 provides improved Cobb 30 values indicating improved water resistance over the control. [0317] These results provide initial proof of concept that the present biowax based barrier coating compositions can be effectively used to coat sheet‐like products for use as a food service package, a beverage service package, or any package suitable for the transport and/or storage of materials comprising oil, water, and/or grease. Example 3: Evaluation of barrier coatings for cupstock base‐sheets [0318] Substrates for barrier coatings were cupstock base‐sheets with a basis wt = 273 g/m2 and a Cobb 5 min of 40 gsm for the bottom side (rough side). [0319] Barrier coating compositions (control 1, BCC 1, and BCC2) were applied at coat weights of 13, 17, and 19 g/m2 (gsm) to the cupstock base‐sheet by roller‐coating, followed by oven curing at 110 °C for 90 secs. A double‐coating (same barrier coating composition for topcoat and basecoat) of each barrier coating composition was applied to a single side of the base‐sheet. Oven curing was performed after each coat application. [0320] Kit tests were performed to evaluate the OGR and Cobb 30 min tests were performed to evaluate the water resistance of the barrier‐coated cupstock base‐sheets. [0321] Results for Cobb 30 min tests are shown in FIG 1. All barrier‐coated samples achieved KIT values of 12. [0322] These results indicate a dose dependent improvement in water resistance for all barrier coating compositions. BCC1, with 43% bio‐content, yielded the same water resistance as the control with 0% bio‐content. Cobb values increased and water barrier properties dropped when the bio‐ content was increased to 50% in the BCC2 barrier dispersion. All barrier‐coated samples achieved a KIT value of 12, indicating excellent OGR. BCC1 and BCC2 coated paper sheets have much better blocking properties than control coated sheets. [0323] These results provide further proof of concept that the present biowax based barrier coating compositions can be effectively used to coat sheet‐like products for use as a food service package, a beverage service package, or any package suitable for the transport and/or storage of materials comprising oil, water, and/or grease. Different coated paper grades require different coat weight
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 ranges. Such as the cupstock needs 20‐25 gram per m2(gsm); fast food wrapping paper needs 6‐10 gsm. Example 4: Evaluation of auxiliary additives in barrier coatings for cupstock base‐sheets [0324] Substrates for barrier coatings were cupstock base‐sheets described in Example 3. [0325] Table 6: Barrier coating compositions (BCC) for basecoats. Barrier Coating Polya Composition BE1 (dry wt%) crylate* Rheology (dry wt%) Modifier** (wt%) Clay (dry wt%) MCC (dry wt%)
[0327] ** pre‐hydrated Ticaloid 5415 [0328] Barrier coating compositions (BCC 3‐4) were prepared for use as basecoats by combining high solids biowax emulsion (BE1), a rheology modifier, and optional auxiliary additives into a polyacrylate carrier, according to Table 6 by a method according to Example 1. [0329] Clay and microcrystalline cellulose (MCC) in the basecoat formulation were evaluated as auxiliary additives to provide enhanced water barrier properties to the topcoat barrier coating composition. Clay and MCC in the basecoat also contribute bio‐based/natural material content to the barrier coatings. [0330] Basecoat: Barrier coating composition BCC 2 (neither clay nor MCC), barrier coating BCC3 with clay (50 dry wt%), and BCC4 with clay (47 dry wt%) and MCC (3 dry wt%) were applied as basecoats to the cupstock base‐sheets by roller‐coating, followed by oven curing at 110 °C for 90 secs. [0331] Topcoat: Barrier coating compositions BCC 1 and BCC2 (neither clay nor MCC) were applied as topcoats to the cupstock base‐sheet by roller‐coating, followed by oven curing at 110 °C for 90 secs. [0332] Basecoats and topcoats for barrier‐coated cupstock Samples 1‐4 are listed in Table 7. Total coat weight and % bio‐content expressed as a wt% of total coating solids are also shown. [0333] Kit tests were performed to evaluate OGR and Cobb 30 min tests were performed to evaluate the water resistance of barrier‐coated cupstock Samples 1‐3. Results are shown in Table 7. [0334] Formulation Targets: (i) greater than 50% bio‐content (renewable raw material) in two coating layers, (ii) Cobb value (30 min) of two‐layer coated sheets < 5 g/m2; and (iii) KIT value = 12.
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 [0335] Table 7: Properties of barrier‐coated cupstock Samples 1‐3. Sample ID Basecoat Topcoat Bio‐content, % Total Coat KIT Cobb 30 min Composition Composition of total solids Weight (gsm) Value value, gsm ed
improvement in water barrier performance. All barrier‐coated samples achieved a KIT value of 12, indicating excellent OGR. Of the samples tested, only Sample 3 achieved all three formulation targets for bio‐content, Cobb 30 min value, and Kit value. [0337] These results provide initial proof of concept that addition of auxiliary additives (e.g., clay and MCC) in the basecoat formulation provide enhancement in both bio‐content and water resistance of double coated paper. Taken together, these results provide further proof of concept that the present biowax based barrier coating compositions with clay and MCC in the basecoat can be effectively used to coat sheet‐like products for use as a food service package, a beverage service package, or any package suitable for the transport and/or storage of materials comprising oil, water, and/or grease. Example 5: Evaluation of barrier coating BCC2 vs PHA for white cupstock base‐sheets [0338] Substrates for barrier coatings were solid bleached sulfate (SBS) white cupstock paperboard base‐sheets with a basis wt = 273 g/m2 and a Cobb 5 min of 42 gsm for the top side. [0339] The barrier coating composition (BCC2) was evaluated as a coating material vs a bio‐based polyhydroxyalkanoate (PHA) barrier coating dispersion, which were applied at coat weights of ~22 g/m2 (gsm) to the cupstock base‐sheet by a cupstock coater. A double‐coating (same barrier coating composition for topcoat and basecoat) of each barrier coating composition was applied to a single side of the base‐sheet. [0340] Kit tests were performed to evaluate the OGR and Cobb 30 min tests were performed to evaluate the water resistance of the barrier‐coated cupstock base‐sheets. [0341] Target water barrier: Cobb 30 min < 5 g/m2 for use in food service items such as cold cup and hot cup. The properties of barrier‐coated cupstock samples are listed in Table 8. [0342] Table 8: Properties of barrier coated white cupstock Composition Total Coat Weight (gsm) KIT Value Cobb 30 min value, gsm
dispersed into polyacrylate delivered equal water barrier and much better oil and grease resistance properties than
ATTY DOCKET NO.1149704.044013 KEMIRA REF NO. US2226 the PHA dispersion on the cupstock application. The BCC2 barrier coating achieved the target water barrier: Cobb 30 min < 5 g/m2, indicating suitable for use in food service items such as cold cup and hot cup. In the preceding disclosure which includes the examples, different procedures and various steps have been described. It will, however, be evident that various modifications and changes may be made thereto, and additional procedures may be implemented, without departing from the broader scope of the procedures as set forth in the claims that follow.