Water-based barrier coating containing sodium bentonite and method for manufacture the same

Description

1 / 22 “WATER-BASED BARRIER COATING CONTAINING SODIUM BENTONITE AND METHOD FOR MANUFACTURING THE SAME” CROSS-REFERENCE ON REQUEST

[001] The priority benefit of Provisional Patent Application No. US 63 / 454,536, filed March 24, 2023, is hereby claimed, and the description is incorporated in full herein by reference. FIELD OF TECHNIQUE

[002] The description refers to water-based barrier coatings and a method for manufacturing water-based barrier coatings containing sodium bentonite. FOUNDATION

[003] Paper-based packaging materials are used around the world. Currently, barrier coatings for paper and packaging applications mainly rely on petroleum-based materials and synthetic polymers, such as waxes, polyvinyl alcohol, and polyolefins (Gironi & Piemonte, 2011). These materials are economical, readily available, and provide a significant barrier against water vapor, oil / grease, and oxygen for packaging applications. However, these materials have major disadvantages, such as the low recyclability of coated paper and non-biodegradability, which can negatively impact the environment. The ideal packaging material in the context of food packaging needs to have an effective barrier against oxygen, water vapor, and oil / grease, and also be from bio-based, recyclable, compostable, and / or otherwise environmentally friendly sources.Barrier property requirements may vary depending on the coating application and the end use of the paper product.

[004] Nanoclays have been used in various applications and are generally found to be advantageous due to their ability to swell in Petition 870250086096, dated 09 / 23 / 2025, p. 6 / 46 2 / 22 water. Sun et al. reported a nanoclay / latex composite to enhance barrier properties in coatings. See Sun et al., Comps Science Tech 67 (2007) 1823-1829. Consistent with conventional expectations and uses of nanoclays, Sun et al. teach that the nanoclay needs to be completely exfoliated in the coating and that cationic surface modifications of the clay and / or the use of dispersants were necessary. Specifically, Sun concludes that the barrier properties of the polymer / clay nanocomposites depend considerably on the degree of exfoliation of the nanoclay layers and that complete exfoliation was necessary to obtain satisfactory barrier performance. SUMMARY

[005] Consistent with the description, a process for preparing an aqueous barrier coating for a paper substrate may include adding a dry powder of chemically unmodified sodium bentonite with a binder; and subjecting the adding mixture to high shear mixing under conditions in which the sodium bentonite disperses in the binder and at least a portion of the sodium bentonite retains a tactoid shape to then form the barrier coating. The binder may be water-based or water-soluble.

[006] Consistent with the description, a process for preparing an aqueous barrier coating for a paper substrate may include adding a dry powder of chemically unmodified sodium bentonite with a polymeric latex binder; and subjecting the adding mixture to high shear mixing under conditions in which the sodium bentonite disperses in the polymeric latex and at least a portion of the sodium bentonite retains a tactoid shape to then form the barrier coating.

[007] The process in accordance with the description may additionally include coating a paper substrate with the barrier coating.

[008] Consistent with the description, an aqueous barrier coating Petition 870250086096, dated 09 / 23 / 2025, p. 7 / 46 3 / 22 may include unmodified sodium bentonite dispersed in a binder, wherein the sodium bentonite is dispersed under high shear conditions in which the sodium bentonite is present in the form of tactoids.

[009] The coating may be dispersant-free. BRIEF DESCRIPTION OF THE DRAWINGS

[010] Figure 1 is a graph showing the resistance to liquid water of barrier-coated papers using the Cobb test for water.

[011] Figure 2 is a graph showing water vapor transmission rates from barrier coatings under tropical conditions at 90% RH and 38 °C.

[012] Figure 3 is a photograph of the oil barrier property test on a coating conforming to the description.

[013] Figures 4A to 4D are particle size distribution graphs of sodium bentonite for use in coatings in accordance with the description.

[014] Figure 5 is a scanning electron microscopy image of a coating conforming to the description showing sodium bentonite tactoids present in the coating.

[015] Figure 6 is a graph showing water vapor transmission rate performance for coatings conforming to the description and conventional coatings formed as single-layer coatings and tested under tropical conditions.

[016] Figure 7 is a graph showing water vapor transmission rate performance for coatings conforming to the description and conventional coatings formed as double-layer coatings and tested under tropical conditions. DETAILED DESCRIPTION

[017] Water-based coatings conforming to the description include chemically unmodified sodium bentonite dispersed in a binder for Petition 870250086096, dated 09 / 23 / 2025, page 8 / 46 4 / 22 advantageously provide a water-based barrier coating. It has been advantageously found that barrier coating properties can be achieved by incorporating dry sodium bentonite, wherein the sodium bentonite used as the raw material in the coating is in its natural hydrophilic state and without exfoliation. Exfoliation of the sodium bentonite can occur under the high shear mixing conditions used in the dispersion of the sodium bentonite in the binder during the preparation of the coatings described. Advantageously, no pre-processing of the sodium bentonite is required before dispersion within the binder.

[018] The coatings described include an unmodified sodium bentonite chemically dispersed in a binder under high shear mixing conditions such that at least a portion of the sodium bentonite is present in the coating in the form of tactoids. Figure 5 is a SEM image of a coating conforming to the description, showing the presence of tactoids in the coating. The coatings described may be water-based barrier coatings.

[019] Methods for manufacturing water-based barrier coatings conforming to the description may include adding a dry powder of chemically unmodified sodium bentonite with a binder and subjecting the adding mixture to high shear mixing under conditions in which the sodium bentonite disperses in the binder and at least a portion of the sodium bentonite retains a tactoid shape.

[020] As used in this document, “sodium bentonite” refers to bentonite that has at least 50% sodium cation. The sodium bentonite used in the methods and coatings described is chemically unmodified sodium bentonite and, optionally, may be mechanically unmodified. As used Petition 870250086096, dated 09 / 23 / 2025, p. 9 / 46 5 / 22 in this document, “non-mechanically modified sodium bentonite” refers to sodium bentonite that may or may not have sodium ion exchange, but which has not been subjected to mechanical shearing prior to incorporation into a coating and retains its natural hydrophilic state. As used in this document, “non-chemically modified sodium bentonite” refers to sodium bentonite that may or may not have sodium ion exchange, but which has not been subjected to chemical modification, such as with organic modifiers. In some coatings described, the sodium bentonite mixed by addition with the binder is not chemically or mechanically modified and, optionally, exfoliated during dispersion of the sodium bentonite in the binder, thus modifying the sodium bentonite present in the final coating by means of mechanical shearing. In some coatings described, the sodium bentonite mixed by addition with the binder is not chemically modified.In some of the coatings described, the sodium bentonite is unmodified chemically. Figures 4A to 4D show the particle size distributions for unmodified sodium bentonites that can be used in the coatings and methods described.

[021] The sodium bentonite used in the coatings and methods described may have less than about 12% moisture. The sodium bentonite is incorporated into the coating binder in a dry particulate or powder state, without pre-swelling or exfoliation, and is dispersed in the binder using high shear mixing. The high shear mixing conditions may be selected and adapted to provide exfoliation of the sodium bentonite while the sodium bentonite is dispersed in the binder. It has been found that the use of sodium bentonite that has been exfoliated during dispersion results in the presence of high-format-factor sodium bentonite in the final coating. High format factor, as used herein, refers to a format factor greater than 4, as measured by the ratio of the Horiba d50 particle size, measured with scattering of Petition 870250086096, dated 09 / 23 / 2025, page 10 / 46 6 / 22 static light, and the Zave particle size, measured with dynamic light scattering. It was advantageously found that exfoliation during dispersion within the binder increases the shape factor of sodium bentonite, while allowing a portion of the sodium bentonite to remain in tactoid form.

[022] Sodium bentonite may contain at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80% montmorillonite.

[023] It was observed that, in the coatings described, at least a portion of the sodium bentonite is retained in a tactoid form. It was surprisingly found that the enhanced barrier coating properties were achieved without complete exfoliation of the sodium bentonite and that, furthermore, at least a portion of the sodium bentonite remained in tactoid form. Figure 5 illustrates that sodium bentonite tactoids remained in the coating. It was observed that the use of the dry powder form of sodium bentonite combined with the high shear mixing used to disperse the sodium bentonite in the binder allows the sodium bentonite to be incorporated into the coatings in such a way that tactoids are present in the binder.

[024] It has been observed that the coatings described achieve improved barrier properties compared to conventional coatings containing talc and kaolin. The coatings described can achieve, if not improved, barrier coating properties compared to coatings containing talc or kaolin with significantly reduced levels of sodium bentonite loading. Additionally, the coatings described can be formed without the need to add dispersant.

[025] Sodium bentonite is dispersed in the binder under high shear mixing conditions that generate a coating in which at least a portion of sodium bentonite is present in tactoid form. Such high shear mixing Petition 870250086096, dated 09 / 23 / 2025, page 11 / 46 7 / 22 can be achieved, for example, by means of a tip speed of about 200 m / min to 1,010 m / min (655 ft / min to about 3,300 ft / min). High shear mixing can be carried out using any known methods or combinations of methods including, but not limited to, the use of a Cowles mixer, sonication, and rotor-stator mixing. High shear mixing may include, for example, sonication for at least 1 minute. Sonication times may be about 1 min to about 40 min, about 10 min to about 30 min, or about 5 min to about 25 min. Other suitable times include approximately 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 and 40 minutes, and values ​​between these numbers and ranges defined by these values. High shear can be performed, for example, under conditions for reduction or for protection against overheating.For example, sonication can be performed using a jacketed container with circulating water and a pulsation method to prevent overheating.

[026] The high-shear mixing process can result in exfoliation of the sodium bentonite during dispersion within the binder; at the same time, it is also possible to maintain the tactoid shape of the sodium bentonite present in the coating. As a result, the sodium bentonite within the coating can have an increased shape factor compared to the starting material before dispersion. The sodium bentonite after dispersion can have a shape factor, for example, greater than 4. The shape factor, as mentioned in this document, is a ratio between the Horiba d50 size, measured by static light scattering, and the Zave size, measured by dynamic light scattering. It has been observed that sodium bentonite with a shape factor greater than 4 can be obtained by high-shear mixing with the binder, such as by sonication for 5 min or more or with the use of a rotor-stator type shear device.

[027] The coating may include any suitable aqueous binder. By Petition 870250086096, dated 09 / 23 / 2025, page 12 / 46 8 / 22 For example, the binder may be an aqueous polymeric latex. For example, non-latex binders may also be used. For example, binders may be one or more of an anionic polymeric latex, such as styrene-butadiene, polyolefin, styrene-acrylates, ethylene-acrylic acid copolymers, ethylene-vinyl alcohol copolymers, polyurethanes, epoxy resins, polyesters, polyolefins, carboxylated styrene-butadiene latex, carboxylated styrene-acrylate latex; polyvinylidene chlorides; polyvinyl chlorides; starches; styrene-acrylic copolymers; styrene-maleic anhydride copolymers; polyvinyl alcohols; polyvinyl acetates; carboxymethyl celluloses; silicones; waxes; neoprene; polyhydroxy ethers; lacquers; polylactic acids; Polylactic acid copolymers; polymers containing fluorine atoms; acrylonitrile copolymers; and carboxylated styrene-butadiene-acrylonitrile copolymers.

[028] Sodium bentonite may be added to the binder in amounts of about 1% by weight to about 20% by weight, about 1% by weight to about 5% by weight, about 3% by weight to about 15% by weight, or about 10% by weight to about 20% by weight, based on a total weight of the coating on a dry weight basis. Other suitable amounts include, based on a total weight of the coating on a dry weight basis, about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 and 20% by weight, and any amounts between these figures and any ranges defined by such amounts. Unless otherwise specified, references to a percentage (%) of sodium bentonite in the coatings in the description refer to a percentage by weight based on the total weight of the coating on a dry weight basis.The loading levels of sodium bentonite can be significantly lower than those required with talc or kaolin in conventional coatings, while still maintaining, or even exhibiting, enhanced barrier properties. For example, the sodium bentonite loading in the coatings described can be 2 to 60 times lower than required. Petition 870250086096, dated 09 / 23 / 2025, p. 13 / 46 9 / 22 for other mineral-based lamellar barrier coatings, such as talc or kaolin coatings.

[029] The coatings of the description are for use on porous coating substrates, such as paper and cardboard. For suitability in such applications, the coatings of the description may have a solids content of about 5% to about 55%, about 15% to about 55%, about 20% to about 40%, about 30% to about 50% or about 10% to about 25%. Other suitable solids contents include about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55% and any values ​​between these numbers and ranges defined by such values.

[030] Coatings prepared by dry addition of sodium bentonite can advantageously have a solids content that is equal to or greater than the solids content of the binder. Conversely, coatings prepared with wet addition of sodium bentonite have a lower solids content than the binder as a result of the liquid present in the fluid paste of sodium bentonite.

[031] The coatings described can be applied by conventional paper coating methods, such as spread bar coating, blade coating, curtain coating, rotogravure coating (etching coating), roll-to-roll machine coating, gluing press, reverse roll coating, hot melt coating, Flexbar coating / flexographic coating, film transfer coating, die coating, wet film applicator coating, coating film molding using filtration and evaporation, dip coating, extrusion coating. The substrate can be coated, for example, with any desired coating weight and / or number of coating layers. For example, coatings can be coated with a coating weight of about 1 g / m2 to about 35 g / m2, about 1 g / m2 to about 25 g / m2, about 5 g / m2 to about 15 g / m2.For example, the weight of the coating could be approximately 1, 2, 3, 4, 5, 6, 7, 8. Petition 870250086096, dated 09 / 23 / 2025, page 14 / 46 10 / 22 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 or 35 g / m2 and any values ​​between these numbers or ranges defined by such values.

[032] The coatings described may be a single-layer coating and may have a coating weight of less than 10 g / m2, for example, about 2 g / m2 to about 10 g / m2 or about 4 g / m2 to about 8 g / m2. Other suitable single-layer coating weights may include about 1, 2, 3, 4, 5, 6, 7, 8 and 9 g / m2 and any values ​​between these numbers and ranges defined by such values. It has been advantageously observed that the beneficial effects of the coatings described, including sodium bentonite as opposed to kaolin or talc, may make the use of single-layer coatings feasible and also the attainment of the desired barrier properties. This is advantageous as double or multi-layer coatings may not be practical in many applications, particularly when multifunctional layers / coatings are used.In single-layer coating weights, the coatings described demonstrated a 31% improvement in barrier properties with a dry addition of 3% sodium bentonite to the coating compared to pure latex. The coatings described that have a dry addition of 3% sodium bentonite also demonstrated a 39% improvement over a comparative coating formulation containing 40% loading of the competitive product Barrisurf™ kaolin clay. The dry addition of sodium bentonite to the coating demonstrated a greater than 30% improvement in barrier properties compared to wet addition.

[033] Porous substrates for use with coatings of the description may generally include any paper or cardboard products for which a barrier coating is desired. Paper substrates on which the coatings of the present description may be applied may include, but are not limited to, solid bleached sulfate (SBS) paper, paperboard Petition 870250086096, dated 09 / 23 / 2025, page 15 / 46 11 / 22 folding box board (FBB), white top liner (WTL), lightweight papers such as fast food packaging, copy paper, coated and uncoated paper and cardboard, coated unbleached kraft paper (CUK), and coated recycled cardboard.

[034] The coatings described may be adapted to provide water vapor transmission rates or other barrier properties based on the intended application of the paper substrate. For example, the barrier coating may provide a water vapor transmission rate (WVTR) <40 g / m² / d under tropical conditions (38 °C and 90% RH) and / or <1 g / m² in a COBB test for water for 60 minutes. Generally, it is understood in the art that the WVTR under tropical conditions for ultra-high barrier applications is <10 g / m² / d, for high barrier applications is <100 g / m² / d, for medium barrier applications is 100-400 g / m² / d, and for low barrier applications is >400 g / m² / d. The barrier coatings conforming to the description may be adapted for any of the aforementioned applications. EXAMPLES Example 1: Dry Addition vs. Wet Fluid Paste Addition

[035] Three different methods were used to create the coating formulations. In the first method, which conforms to the description, sodium bentonite was added to the latex as a dry powder; this will be referred to as “dry addition” hereafter. A second comparative method was used in which sodium bentonite was processed to become a fluid paste in water before being added to the latex; this is referred to as “Acumer-Free”. In a third comparative example, a chemical dispersant was first added to the water, then the dry sodium bentonite powder, and finally this pre-dispersed fluid paste of sodium bentonite was added to the latex; this is referred to as “0.08% Acumer”. Dry addition: Dry addition of 5% sodium bentonite. Petition 870250086096, dated 09 / 23 / 2025, page 16 / 46 12 / 22

[036] The aqueous barrier coating in accordance with the description was prepared as follows: In a 1000 ml steel container, 370 g of Tykote® 1004 styrene-butadiene latex at a solids content of 52% were weighed. To this were added 10.7 g of sodium bentonite at 10% moisture and 27.7 g of water. The resulting fluid paste was thoroughly mixed using a Cowles 2500HV Premier type mixer with a 6.35 cm (2.5 inch) diameter blade at a tip speed of 897.64 m / min (2945 ft / min) for 30 minutes. By means of the oven drying method, the final solids content of the formulation was determined to be 45%. Without Acumer: Wet addition of 5% sodium bentonite without dispersant.

[037] A fluid sodium bentonite paste was created in water by adding 11.1 g of dry sodium bentonite at 10% moisture to 200 g of water. Then, using a Cowles 2500HV Premier model mixer with a 6.35 centimeter (2.5 inch) diameter blade, the suspension was stirred at a tip speed of 897.64 m / min (2,945 ft / min) for 15 minutes. By means of the oven drying method, the solids content of this water-based fluid sodium bentonite paste was determined to be 5%. The barrier coating formulation was generated in a 1,000 ml steel container by mixing 370 g of Tykote® 1004 styrene-butadiene latex at a solids content of 52% and 178.1 g of sodium bentonite flow paste prepared at a solids content of 5%. The mixture was then stirred at a peak speed of 897.64 m / min (2,945 ft / min) for 15 min using the same Cowles-type mixer.Using the oven drying method, the final solids content of the formulation was determined to be 45%. 0.08% Acumer: Wet addition of 5% sodium bentonite with dispersant.

[038] A fluid paste of sodium bentonite was created in 300 g of water by Petition 870250086096, dated 09 / 23 / 2025, page 17 / 46 13 / 22 halfway through the addition of 0.0608 g of ACUMER 9300 at a solids content of 45% followed by 38 g of powder at 10% moisture. The mixture was stirred for 15 minutes using a Cowles 2500HV Premier mixer with a 6.35 cm (2.5 inch) diameter blade at a tip speed of 897.64 m / min (2,945 ft / min). By oven drying, the final solids content of the fluid paste was determined to be 11%. In order to manufacture the barrier formulation, 70.4 g of the fluid paste at a solids content of 11% were added to 304 g of Tykote® 1004 styrene-butadiene latex at a solids content of 52%. The resulting barrier formulation was agitated for 15 minutes at a tip speed of 897.64 m / min (2,945 ft / min) using the same Cowles-type mixer. Coating

[039] A spread rod coating method was used to manufacture barrier coatings on a 350 g / m2 SBS (bleached sulfate solid) board. Each board has double-layer coatings of the same formulation, and rod numbers 4-13 were used to manufacture different coating weights. Coating weights were manufactured with average coating weights of 13-15 g / m2 and 23-25 ​​g / m2. The paper coated with the barrier formulation was then tested for resistance to liquid water (Cobb test for water) by TAPPI 441, for water vapor transmission rate (WVTR) by TAPPI T 464, and for oil and grease barrier (OGR) by the Cobb test for oil. The Cobb method for oil is a modified TAPPI 441 method for testing OGR.In this procedure, the surface of the barrier-coated papers was covered with oil-saturated blotting paper for 30 minutes, after which the weight change caused by oil absorption was measured to determine the Cobb test number for oil. The results for the barrier coatings are shown in Figures 1, 2, and 3. Example 2: Determining the Format Factor and the Effects of Conditions Petition 870250086096, dated 09 / 23 / 2025, page 18 / 46 14 / 22 Mixture in Format Factor

[040] Chemically unmodified crude sodium bentonite having a moisture content of 8% and a dry particle size at least 99.00% finer than 74 microns (200 mesh) and a wet particle size at least 99.75% finer than 74 microns (200 mesh). The particle size of dispersed sodium bentonite was determined using the Horiba LA950 static light scattering instrument. A 1.0% bentonite suspension was created by adding 0.5 g of bentonite powder to 50 ml of a DL water solution with a 0.005% concentration of DAXAD® 30 dispersant. The resulting suspension was sonicated using a 1.27 cm (0.5 inch) probe set at 1.5 for 8 minutes for dispersion. The dispersed suspension was added by dripping to the Horiba LA950 cell in order to achieve a red laser percentage transmittance of 89-91%, and the particle size was determined using standard fitting and refractive indices for calcium carbonate.This method measures a particle size related to the major basal plane dimension of the bentonite.

[041] Samples of undispersed sodium bentonite were also tested. A water suspension of sodium bentonite at any solids content of about 1 to 10% can be prepared, and varying degrees of shear can be applied using any type of mixing or sonication equipment. This suspension is added to the Horiba LA950 cell, and the particle size is measured as described above. Table 1 Description D10 (pm) D20 (pm) D50 (pm) D90 (pm) D95 (pm) D98 (pm) Sodium bentonite - dispersed, sonicated 1.19 1.57 2.83 8.77 11.71 15.73 Sodium bentonite - in water, shear for 2 hours with rotor-stator 1.47 1.88 3.12 6.76 8.31 10.31 Petition 870250086096, dated 09 / 23 / 2025, page 19 / 46 15 / 22

[042] The particle size of sodium bentonite was also determined by dynamic light scattering (DLS) using a Malven Zetasizer 1000 instrument. A dispersed or undispersed suspension could be used. The suspension was diluted to a solids content of 0.1% using DI water. The diluted suspension was transferred to an instrument cuvette (1 cm x 1 cm, plastic with all transparent faces), and the cuvette was placed in the instrument's measuring chamber. The default software settings were used to measure the size using water as a solvent and the refractive index of sodium bentonite (1.503). The resulting Zave value (the hydrodynamic diameter) is reported. This instrument is designed to measure nanoparticles, and therefore this technique was used to provide a value related to sodium bentonite plates, although much larger than the smallest thickness dimension of the plates.Zave values ​​measured from sodium bentonite ranged from 500 to 1,500 nm.

[043] It was determined that the shape factor (SF) of bentonite could be calculated as a ratio between two particle size methods – using the ratio between static light scattering diameters (Horiba LA-950) and dynamic light scattering (DLS) diameters. With bentonite, it was observed that sedimentation could not be used due to its extremely long settling time. The shape factor (SF) was calculated by taking the ratio between the median particle size (d50) determined by Horiba light scattering and the Zave particle size determined using Malvern Zetasizer 1000 DLS in microns. The resulting SF values ​​for sodium bentonite can range from 3.5 to 7, with higher values ​​indicating a higher degree of delamination and a higher particle aspect ratio.

[044] Two samples with high and low SF were manufactured as follows: Low SF: A fluid paste of sodium bentonite with a solids content of 5%. Petition 870250086096, dated 09 / 23 / 2025, p. 20 / 46 16 / 22 in DI water was manufactured as in the example above without Acumer, except that the volume was 500 ml and the high-speed mixing with the Cowles was only at 2,000 rpm for 5 minutes. SF Alto: An additional 500 ml of fluid paste with a 5% solids content was sonicated for a total of 20 minutes in a water-cooled beaker with constant mixing using a propeller-type stirrer. To avoid overheating, the sonication was switched on and off in the following cycles: 10 seconds on / 20 seconds off, for a total of 20 minutes on. Table 2 Description Hor d10 Hor d50 Hor d90 ZS Zave (one) SF (Hd50 / Zave) Cowles 2,000 rpm, 5 min. 2.10 4.30 8.23 ​​1.11 3.87 Sonication for 20 min. 1.13 2.91 9.12 0.548 5.31

[045] This demonstrates that the mixing method used to disperse sodium bentonite within the binder can be selected for manufacturing a final composition with sodium bentonite having either a high or low formate factor. It has been observed that high shear mixing methods, such as sonication, result in materials with a high formate factor. Example 3: Effect of Format Factor and Dry Addition on Barrier Performance

[046] Coatings were prepared, in accordance with the description, having sodium bentonite with high and low formate factors, as well as with dry and wet addition of sodium bentonite. Chemically unmodified sodium bentonite, as described in Example 2, was used with the starting material in the coatings of the present description. The coatings in accordance with the description each included 3% sodium bentonite on a dry weight basis. The barrier performances of these coatings were compared to each other, as well as to a Tykote® 1004 (pure latex) coating and a coating containing Barrisurf™LX (kaolin). Petition 870250086096, dated 09 / 23 / 2025, page 21 / 46 17 / 22

[047] A coating conforming to the description having a 3% dry addition of sodium bentonite with a low formate factor was prepared by combining 150 g of Tykote® 1004 with 2.6 g of dry sodium bentonite powder. In order to create the low formate factor formulation, this mixture was stirred at 2,000 RPM for 5 minutes using a 6.35 centimeter (2.5 inch) diameter Cowles blade. The formulation was diluted to 47% by adding DI water. This formulation was kept overnight; then the viscosity, pH and solids were measured.

[048] A coating conforming to the description having a 3% dry addition of sodium bentonite with a high formate factor was prepared by combining 150 g of Tykote® 1004 with 2.6 g of dry sodium bentonite powder. For the high formate factor formulation, this mixture was stirred at 2,000 RPM for 5 minutes, followed by sonication for 20 minutes with a pulse function, alternating between 30 seconds on and 30 seconds off. The pulse function was used to prevent overheating. The formulation was diluted to 47% by adding DI water. This formulation was kept overnight; then the viscosity, pH, and solids were measured.

[049] A coating conforming to the description having a wet addition of 3% sodium bentonite with a low formate factor was first prepared by forming a fluid paste of sodium bentonite. The fluid paste was prepared as described in Example 3 to prepare a low formate factor sodium bentonite fluid paste. In particular, 25 g of dry sodium bentonite powder was mixed with 475 g of water, sheared at 2,000 RPM for 5 minutes using a 6.35 cm (2.5 inch) Cowles blade in order to obtain a final fluid paste solids concentration of 5%. Subsequently, 150 g of Tykote® 1004 were combined with 48.2 g of the wet fluid paste with 5% sodium bentonite. The Tykote® 1004 latex and the fluid paste of bentonite Petition 870250086096, dated 09 / 23 / 2025, page 22 / 46 18 / 22 sodium was then mixed at 800 RPM for 15 minutes using a propeller-type suspended mixer. This formulation was kept overnight; then, viscosity, pH, and solids were measured.

[050] A coating conforming to the description having a wet addition of 3% sodium bentonite with a high formate factor was first prepared by forming a fluid paste of sodium bentonite. The fluid paste was prepared as described in Example 3 for preparing a high formate factor sodium bentonite fluid paste. In particular, 25 g of dry sodium bentonite powder was mixed with 475 g of water, sheared at 2,000 RPM for 5 minutes using a 6.35 cm (2.5 inch) Cowles blade. In addition to obtaining a high formate factor, the same formulation was sonicated for 20 minutes with a pulse function, alternating between 10 seconds on and 20 seconds off. The pulse function was used to prevent overheating. The final solids content of the sodium bentonite fluid paste was 5%. 150 g of Tykote® 1004 were combined with 48.2 g of moist fluid paste containing 5% sodium bentonite.Tykote® 1004 latex and sodium bentonite fluid paste were then mixed at 800 RPM for 15 minutes using a propeller-type suspended mixer. This formulation was kept overnight; then, viscosity, pH, and solids were measured.

[051] The comparative example coating Barrisurf™LX (kaolin) was prepared as a formulation with 40% Barrisurf™ LX - Tykote® 1004. 150 g of Tykote® 1004 were combined with 84.4 g of Barrisurf™ LX flow paste. The Barrisurf™ LX flow paste had a solids content of 61.6%. This mixture was then mixed at 800 RPM for 15 minutes using a propeller-type suspended mixer. This formulation was kept overnight; then, the viscosity, pH, and solids were measured. Petition 870250086096, dated 09 / 23 / 2025, page 23 / 46 19 / 22

[052] For each of the coating formulations, the coatings were applied to a 175 g / m2 white topcoat using an automated spreader bar coater at a speed of 40 m / min. The coatings were dried in an oven at 103 °C for 10 minutes, followed by conditioning in the CTH room for 24 hours. Both single and double layers of coating were applied. For the single-layer coating, the desired coating weight was 5.8 ± 0.4 g / m2; whereas, for the double-layer coating, the desired coating weight was 10.8 ± 0.3 g / m2. Subsequently, circles with a diameter of 7.62 cm were cut and used for WVTR testing under tropical conditions (38 °C, 90% RH).

[053] Table 3 provides the viscosity, pH and solids content of the prepared coating formulations. Table 3 Sample Description Viscosity at 100 RPM-Pas (cP) pH % Solids Tykote® 1004 0.27 (270) 8.08 52% Barrisurf™ Lx 0.11 (106.8) 8.13 55.4% Wet addition of 3% low-format bentonite 75.11 (75) 8.36 40.3% Wet addition of 3% high-format bentonite 0.26 (206) 8.36 40.1% Dry addition of 3% low-format sodium bentonite 0.18 (180) 8.32 47.1% Dry addition of 3% high-format sodium bentonite 0.65 (650) 8.03 46.1% *3% sodium bentonite refers to 3% by weight of sodium bentonite based on the total weight of the coating on a dry weight basis. Petition 870250086096, dated 09 / 23 / 2025, page 24 / 46 20 / 22

[054] The water vapor transmission rate (WVTR) was tested by TAPPI T 464 under tropical conditions (38 °C, 90% RH). Referring to Figure 6, the single-layer coatings described demonstrated a significant improvement in water vapor transmission rate properties compared to the Tykote® 1004 coating alone and the coating containing Barrisurf™LX (kaolin). Furthermore, an improvement in water vapor transmission rate performance was also observed for the dry addition of sodium bentonite in the coatings described compared to the wet addition. Finally, an improvement in water vapor transmission rate performance was also observed during the use of the coating formulation process that results in the presence of a high-format-factor sodium bentonite in the coating. In particular, the following quantitative improvements in performance are observed:

[055] A 31% reduction in WVTR for formulation containing sodium bentonite with a high aspect ratio at a dry addition of 3% compared to pure latex.

[056] A 36% reduction in WVTR for the formulation containing dry-added sodium bentonite with a high aspect ratio compared to the formulation containing wet-added sodium bentonite with a high aspect ratio.

[057] A 32% reduction in WVTR for the formulation containing dry-added sodium bentonite with a low aspect ratio compared to the formulation containing wet-added sodium bentonite with a low aspect ratio.

[058] A 39% reduction in WVTR for a formulation containing sodium bentonite with a high aspect ratio at a dry addition of 3% compared to Barrisurf™LX.

[059] Referring to Figure 7, the significance of the reduction in WVTR between the coatings described and the comparative coatings Tykote® 1004 and BarrisurfTM (kaolin) is less evident when a double-layer coating is used. Petition 870250086096, dated 09 / 23 / 2025, page 25 / 46 21 / 22 It is also observed that there is a reduction in water vapor transmission rates, particularly with regard to the dry addition of sodium bentonite. Furthermore, it has been surprisingly and beneficially observed that coatings conforming to the present description, with dry addition of sodium bentonite with a high format factor, can provide similar, or even improved, water vapor transmission rate performance when formed as a single-layer coating compared to the double-layer coatings of Tykote® 1004 and Barrisurf™ coatings. Therefore, the coatings described can eliminate the need for double-layer coatings, which can be complicated and impractical in some applications, while maintaining at least the same level of barrier performance as a double-layer coating of conventional kaolin coatings.

[060] The above description is provided for the sake of objectivity and understanding only, and unnecessary limitations should not be inferred from the description, as modifications covered by the scope of the description may be apparent to persons of ordinary skill in the art.

[061] All patents, patent applications, government publications, government regulations and literature references cited in this descriptive report are incorporated herein in their entirety by reference. In case of conflict, this description, including the definitions, shall prevail.

[062] Throughout this descriptive report, when compounds, compositions, methods and / or processes are described as including components, steps or materials, it is understood that the compounds, compositions, methods and / or processes may also comprise, consist essentially of, or consist of any combination of the aforementioned components or materials, unless otherwise described. Component concentrations may be expressed in terms of weight concentrations, unless specifically indicated otherwise. Petition 870250086096, dated 09 / 23 / 2025, page 26 / 46 22 / 22 meaning that combinations of components include homogeneous and / or heterogeneous mixtures, as would be understood by a person of ordinary skill in the art, given the description above. Petition 870250086096, dated 09 / 23 / 2025, page 27 / 46

Claims

1 / 8 CLAIMS 1. A process for preparing an aqueous barrier coating for a paper substrate, CHARACTERIZED in that it comprises: mixing by addition a dry powder of chemically unmodified sodium bentonite with a binder; and subjecting the addition mixture to high shear mixing under conditions in which the sodium bentonite disperses in the binder and at least a portion of the sodium bentonite maintains a tactoid shape to then form the barrier coating, wherein the binder is water-based or water-soluble.

2. Process according to claim 1, CHARACTERIZED in that the binder comprises a polymeric latex.

3. Process according to claim 2, CHARACTERIZED in that the polymeric latex is an anionic polymeric latex.

4. Process according to claim 3, CHARACTERIZED in that the anionic polymeric latex comprises one or more of styrene-butadiene, polyolefin, styrene-acrylates, ethylene-acrylic acid copolymers, ethylene-vinyl alcohol copolymers, polyurethanes, epoxy resins, polyesters, polyolefins and carboxylated styrene-butadiene.

5. A process, according to any of the preceding claims, CHARACTERIZED in that the binder comprises one or more of the following: carboxylated styrene-acrylate latex, polyvinylidene chlorides, polyvinyl chlorides, starches, styrene-acrylic copolymers, styrene-maleic anhydride copolymers, polyvinyl alcohols, polyvinyl acetates, carboxymethyl celluloses, silicones, waxes, neoprene, polyhydroxy ethers, lacquers, polylactic acids, polylactic acid copolymers, polymers containing fluorine atoms, acrylonitrile copolymers, and carboxylated styrene-butadiene-acrylonitrile copolymers.

6. Process for preparing an aqueous barrier coating for a paper substrate, as per Petition 870250086096, dated 09 / 23 / 2025, p. 28 / 46 2 / 8, CHARACTERIZED by the suit comprising: mixing by addition a dry powder of chemically unmodified sodium bentonite with an aqueous polymeric latex binder; and subjecting the addition mixture to high shear mixing under conditions in which the sodium bentonite disperses in the polymeric latex and at least a portion of the sodium bentonite maintains a tactoid shape to then form the barrier coating.

7. Process according to claim 6, CHARACTERIZED in that the polymeric latex is an anionic polymeric latex.

8. Process according to claim 7, CHARACTERIZED in that the anionic polymeric latex comprises one or more of styrene-butadiene, polyolefin, styrene-acrylates, ethylene-acrylic acid copolymers, ethylene-vinyl alcohol copolymers, polyurethanes, epoxy resins, polyesters, polyolefins and carboxylated styrene-butadiene.

9. Process, according to any of the preceding claims, CHARACTERIZED in that the aqueous barrier coating has a solids content of about 5% to about 55%.

10. Process, according to any of the preceding claims, CHARACTERIZED in that high shear mixing is carried out at a tip speed of about 200 m / min to 1,010 m / min (655 ft / min to about 3,300 ft / min).

11. A process, according to any of the preceding claims, CHARACTERIZED in that the dry powder of chemically unmodified sodium bentonite comprises less than 12% moisture.

12. Process, according to any of the preceding claims, CHARACTERIZED in that high shear mixing is carried out using a Cowles mixer, a sonicator or a rotor-stator type mixer. Petition 870250086096, dated 09 / 23 / 2025, p. 29 / 46 3 / 8 13. Process according to claim 12, CHARACTERIZED in that high shear mixing is carried out using a sonicator.

14. Process, according to claim 13, CHARACTERIZED in that it comprises sonication for about 1 min to about 40 min.

15. Process, according to any of the preceding claims, CHARACTERIZED in that the high shear mixing is carried out under conditions to exfoliate the sodium bentonite while the sodium bentonite is dispersed in the binder so that the sodium bentonite present in the coating has a shape factor greater than 4, as measured by a ratio between the Horiba d50 particle size, measured with static light scattering, and the Zave particle size, measured with dynamic light scattering.

16. Process, according to any of the preceding claims, CHARACTERIZED in that dry powder of chemically unmodified sodium bentonite is added to the binder in an amount of about 1% by weight to about 20% by weight based on the total weight of the mixture by addition on a dry weight basis.

17. A process, according to any of the preceding claims, CHARACTERIZED in that the addition mixture is free of dispersants.

18. Process, according to any of the preceding claims, CHARACTERIZED in that the chemically unmodified sodium bentonite is chemically and mechanically unmodified sodium bentonite.

19. Process for preparing a barrier coating for a paper substrate CHARACTERIZED in that it comprises: mixing by addition a dry powder of chemically unmodified sodium bentonite with a binder; subjecting the addition mixture to high shear mixing under conditions in which the sodium bentonite disperses in the binder and at least a portion of the sodium bentonite maintains a tactoid shape to then form the barrier coating; and coating the paper substrate with the barrier coating having a coating weight of about 1.5 g / m2 to about 25 g / m2, where the binder is water-based or water-soluble.

20. Process, according to claim 19, CHARACTERIZED in that the coating weight is less than 10 g / m2.

21. Process, according to claim 19 or 20, CHARACTERIZED in that the paper substrate is solid bleached sulfate paper (SBS), folding box board (FBB), white top liner (WTL), low basis weight paper packs, copy paper, coated or uncoated paper and cardboard, Coated Unbleached Kraft (CUK), Coated Recycled Cardboard.

22. Process, according to any one of claims 19 to 21, CHARACTERIZED in that the binder comprises a polymeric latex.

23. Process according to claim 22, CHARACTERIZED in that the polymeric latex is an anionic polymeric latex.

24. Process according to claim 23, CHARACTERIZED in that the anionic polymeric latex comprises one or more of styrene-butadiene, polyolefin, styrene-acrylates, ethylene-acrylic acid copolymers, ethylene-vinyl alcohol copolymers, polyurethanes, epoxy resins, polyesters, polyolefins and carboxylated styrene-butadiene.

25. Process, according to any one of claims 19 to 24, CHARACTERIZED in that the binder comprises one or more of carboxylated styrene-acrylate latex, polyvinylidene chlorides, polyvinyl chlorides, ami Petition 870250086096, dated 09 / 23 / 2025, page. 31 / 46 5 / 8 of, styrene-acrylic copolymers, styrene-maleic anhydride copolymers, polyvinyl alcohols, polyvinyl acetates, carboxymethyl celluloses, silicones, waxes, neoprene, polyhydroxy ethers, lacquers, polylactic acids, polylactic acid copolymers, polymers containing fluorine atoms, acrylonitrile copolymers and carboxylated styrene-butadiene-acrylonitrile copolymers.

26. Process, according to any one of claims 19 to 25, CHARACTERIZED in that the aqueous barrier coating has a solids content of about 5% to about 55%.

27. Process, according to any one of claims 19 to 26, CHARACTERIZED in that high shear mixing is carried out at a tip speed of about 200 m / min to 1,010 m / min (655 ft / min to about 3,300 ft / min).

28. Method, according to any one of claims 19 to 27, CHARACTERIZED in that the dry powder of chemically unmodified sodium bentonite comprises less than 12% moisture.

29. Process, according to any one of claims 19 to 28, CHARACTERIZED in that high shear mixing is carried out using a Cowles mixer, a sonicator or a rotor-stator type mixer.

30. Process according to claim 29, CHARACTERIZED in that high shear mixing is carried out using a sonicator.

31. Process according to claim 30, CHARACTERIZED in that it comprises sonication for about 1 min to about 40 min.

32. Process, according to any one of claims 19 to 31, CHARACTERIZED in that the high shear mixing is carried out under conditions to exfoliate the sodium bentonite while the sodium bentonite is dispersed in the binder so that the sodium bentonite present in the coating has a shape factor greater than 4, as measured by a ratio between the Horiba d50 particle size, measured with static light scattering, and the Zave particle size, measured with dynamic light scattering.

33. Process, according to any one of claims 19 to 32, CHARACTERIZED in that unmodified dry sodium bentonite powder is added to the binder in an amount of about 1% by weight to about 20% by weight based on the total weight of the mixture by addition on a dry weight basis.

34. Process, according to any one of claims 19 to 33, CHARACTERIZED in that the addition mixture is free of dispersants.

35. Process, according to any one of claims 19 to 34, CHARACTERIZED in that the chemically unmodified sodium bentonite is chemically and mechanically unmodified sodium bentonite.

36. Aqueous barrier coating CHARACTERIZED in that it comprises: chemically unmodified sodium bentonite dispersed in a binder, wherein the sodium bentonite is dispersed under high shear conditions in which at least a portion of the sodium bentonite is present in the form of tactoids, wherein the binder is water-based or water-soluble.

37. Coating, according to claim 36, CHARACTERIZED in that the sodium bentonite has a shape factor greater than 4, as measured by a ratio between the Horiba d50 particle size, measured with static light scattering, and the Zave particle size, measured with dynamic light scattering.

38. Coating, according to claim 36 or 37, CHARACTERIZED in that the binder comprises a polymeric latex.

39. Coating according to claim 38, CHARACTERIZED in that the polymeric latex is an anionic polymeric latex.

40. Coating, according to claim 39, CHARACTERIZED Petition 870250086096, dated 09 / 23 / 2025, page 33 / 46 7 / 8 by the fact that the anionic polymeric latex comprises one or more of styrene-butadiene, polyolefin, styrene-acrylates, ethylene-acrylic acid copolymers, ethylene-vinyl alcohol copolymers, polyurethanes, epoxy resins, polyesters, polyolefins and carboxylated styrene-butadiene.

41. Process, according to any one of claims 36 to 40, CHARACTERIZED in that the binder comprises one or more of the following: carboxylated styrene-acrylate latex, polyvinylidene chlorides, polyvinyl chlorides, starches, styrene-acrylic copolymers, styrene-maleic anhydride copolymers, polyvinyl alcohols, polyvinyl acetates, carboxymethyl celluloses, silicones, waxes, neoprene, polyhydroxy ethers, lacquers, polylactic acids, polylactic acid copolymers, polymers containing fluorine atoms, acrylonitrile copolymers and carboxylated styrene-butadiene-acrylonitrile copolymers.

42. Coating, according to any one of claims 36 to 41, wherein the aqueous barrier coating is CHARACTERIZED in that it has a solids content of about 5% to about 55%.

43. Coating, according to any one of claims 36 to 42, CHARACTERIZED in that sodium bentonite is present in the coating in an amount of about 1% by weight to about 20% by weight based on the total weight of the coating on a dry weight basis.

44. Coating, according to any one of claims 36 to 43, CHARACTERIZED in that the coating is free of dispersants.

45. Coating, according to any one of claims 36 to 44, wherein the coating is CHARACTERIZED in that it has a solids content that is equal to or greater than the solids content of the binder.

46. ​​Barrier-coated paper substrate CHARACTERIZED by the suit comprising a paper substrate coated with the coating as defined in any one of claims 36 to 45. Petition 870250086096, dated 09 / 23 / 2025, p. 34 / 46 8 / 8 47. Barrier-coated paper substrate according to claim 46, wherein the paper substrate is CHARACTERIZED in that it is solid bleached sulfate (SBS) paper, folding box board (FBB), white top liner (WTL), low basis weight paper packs, copy paper, coated or uncoated paper and cardboard, Coated Unbleached Kraft (CUK) paper, Coated Recycled Cardboard.

48. Barrier-coated paper substrate according to claim 46 or 47, CHARACTERIZED in that the coating has a coating weight of less than 10 g / m2 and a water transmission rate of less than 400 g / m2 / d. Petition 870250086096, dated 23 / 09 / 2025, p. 35 / 46

Images