WO2009114071A1

WO2009114071A1 - Aqueous barrier coating composition with kaolin clay filler and acrylic matrix polymer

Info

Publication number: WO2009114071A1
Application number: PCT/US2009/001229
Authority: WO
Inventors: Michele Farrell; Harris A. Goldberg; Carrie A. Fenney
Original assignee: Inmat Inc.
Priority date: 2008-03-14
Filing date: 2009-02-27
Publication date: 2009-09-17

Abstract

An aqueous barrier coating composition in the form of a dispersion consisting of : (a) water; (b) an acrylic matrix polymer; (c) a platy to hyperplaty kaolin filler having an average shape factor of at least 40:1, the filler being pre-treated with acid prior to being combined with the acrylic matrix polymer, the composition optionally including a disperdant and/or a thickener and being further characterized in that: (i) the composition has a solids content of from 20 to 70 percent by weight; (ii) the composition has a weight ratio of acrylic matrix polymer: kaolin filler of from 4:1 to 0.75:1; and (iii) a film formed from the composition exhibits at least 25-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer.

Description

AQUEOUS BARRIER COATING COMPOSITION WITH KAOLIN CLAY FILLER AND ACRYLIC MATRIX POLYMER

Claim for Priority

This non-provisional application claims the benefit of the filing date of

U.S. Provisional Patent Application Serial No. 61/069,461, of the same title, filed March 14, 2008. The priority of U.S. Provisional Patent Application Serial No. 61/069,461 is hereby claimed and the disclosure thereof is incorporated into this application by reference.

Joint Research Agreements

The claimed inventions were made by, on behalf of, and/or in connection with one or more of the following parties to joint research agreements: MeadWestvaco Corporation, Imerys Clays Inc., and InMat Inc. The applicable agreements are: (1) A three party JDA effectively dated February 28, 2008 among MeadWestvaco Corporation, Imerys Clays Inc., and InMat Inc.; (2) a JDA effectively dated June 1, 2006 between MeadWestvaco Specialty Chemicals, LLC and Imerys Clays Inc.; and (3) a JDA effectively dated May 3, 2006 between MeadWestvaco Corporation and InMat Inc. One or more of these agreements were in effect on and before the date the claimed inventions were made, and the claimed inventions were made as a result of activities undertaken within the scope of one or more of the aforesaid agreements.

Field of Invention

The present invention relates generally to polymer/clay dispersions which are used to provide coatings having enhanced barrier properties. The coating compositions have a high barrier to gas permeation and are thus suitable for packaging perishables such as milk, foodstuffs and the like as well as oxygen sensitive inks, electronic components and so forth. The invention also relates to a method of making aqueous concentrated barrier coating compositions by selectively removing a portion of the aqueous medium.

Background of the Invention Barrier coatings which prevent, reduce, or inhibit the permeation of a selected substrate with a gas, vapor, chemical and/or aroma have been widely described, and such coatings are used in a variety of industries, e.g., the packaging industry, automobile industry, paint industry, and tire industry. For example, butyl rubber in automobile tires has been coated with formulations which include a polymer and a platelet filler, in order to reduce the air permeability of the tire. See, e.g., United States Patent Nos. 4,911,218 and 5,049,609. Tires with integral innerliners are disclosed in United States Patent No. 5,178,702. Similarly, it has been well described in the literature that barrier properties are of great importance for packaging food, beverage, or other products that are sensitive to environmental influences.

United States Patent Application Publication No. US2004/0121079 of Urscheler et al., which is incorporated herein by reference in its entirety, discloses a method of producing a multi-layer coated substrate having improved barrier properties. The method described therein allows one to produce a coated substrate having at least two layers of coating which imparts different barrier functionalities including oil and/or grease barrier functionality, water vapor barrier functionality, water resistance functionality, solvent barrier functionality, aroma barrier functionality, and oxygen barrier functionality.

It has also been reported that certain hydrous mineral materials, such as for example, kaolin, imparts certain advantageous properties in a variety of coating compositions. For example, United States Patent No. 6,758,895 to Wesley, which is incorporated herein by reference in its entirety, discloses a hyperplaty particulate mineral material suitable for use as an opacifying pigment or filler. United States Patent Nos. 7,208,039; 7,214,264 and 7,226,005 to Jones et al, all of which are incorporated herein by reference in their entirety, disclose hyperplaty clays and their use in coating and filling. United States Patent Nos. 6,616,749 and 6,814,796 to Husband et al, which are incorporated herein by reference in their entirety, disclose a platy kaolin useful for coating. United States Patent Nos. 6,537,363 and 6,610, 137 to Golley et al. , which are incorporated herein by reference in their entirety, also disclose a platy kaolin useful for coating. United States Patent No. 6,564,199 to Pruett et al., which is incorporated herein by reference in its entirety, likewise discloses a platy kaolin for coating. United States Patent No. 6,808,559 to Golley et al, which is incorporated herein by reference in its entirety, discloses a platy kaolin useful in coating and filling compositions.

Despite the advances in the art, there exists a need for an aqueous coating composition that exhibits enhanced gas barrier properties, which may be applied to various substrates using existing technology without the need for highly specialized equipment that requires large capital investment to convert existing production lines or install new production lines.

Summary of the Invention There is provided an aqueous barrier coating composition in the form of a dispersion consisting of: (a) water; (b) an acrylic matrix polymer; (c) a kaolin filler having an average shape factor of at least about 40:1; the filler being pre- treated with acid prior to being combined with the acrylic matrix polymer. The composition optionally includes a dispersant and/or a thickener and is further characterized in that: (i) the composition has a solids content of from 20 to 70 percent by weight; (ii) the composition has a weight ratio of acrylic matrix polymer: kaolin of from 4:1 to 0.75:1; and (iii) a film formed from the composition exhibits at least 25-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer. The dispersions are preferably concentrated after formulation and prior to application to a substrate, which surprisingly increases the barrier properties of the films produced.

The dispersions are readily converted into barrier films by conventional techniques and are processable much like conventional clay coatings.

Still further features and advantages of the invention are apparent from the following description.

Detailed Description of the Invention

The present invention is unique in that it provides for barrier coating compositions, films, and coated articles that achieve substantial reductions in gas permeability and/or permeation rate by providing a dispersion of platy or hyperplaty kaolin and acrylics suitable for film-forming. The subsequent films, coatings, and coated articles can provide improved barrier properties.

The results obtained with (non-elastomeric) acrylics are surprising, for example, when viewed relative to the relatively dilute elastomeric nanocomposite formulations of United States Patent No. 6,087,016, "Barrier Coating of an

Elastomer and a Dispersed Layered Filler in a Liquid Carrier" July 1 1, 2000 to Feeney et al. or the relatively concentrated coating compositions of United States Patent Nos. 7,208,039; 7,214,264 and 7,226,005 to Jones et al. The results are unexpected, in part, because aqueous dispersions of non-elastomeric polymers usually retain their spherical morphology through the process of forming a film from the aqueous dispersion. This means that one would expect it to be very difficult to get good dispersion of the hyperplaty kaolin filler in the final coating, and one skilled in the art would expect that the filler would coalesce at the interfaces between the polymer particles during film formation. The large reductions in barrier properties that have been achieved indicate that this coalescence did not occur to a large enough extent to limit the reduction in permeability. Furthermore, the coatings formed from the compositions of this invention also retain the high opacity, characteristic of kaolin, thus exhibiting high gloss, smoothness and/or brightness of the material.

The invention is described in detail below for purposes of illustration only.

Modifications within the spirit and scope of the invention, set forth in the appended claims, will be readily apparent to one of skill in the art. Unless defined otherwise, terminology and abbreviations, as used herein, have their ordinary meaning. Following are some exemplary definitions of terms used in this specification and the appended claims.

" Aqueous Dispersion" and like terminology refers to emulsions, latexes and stable suspensions of solids in water.

As used herein, the phrase "non-elastomeric polymer," and like terminology, includes those polymeric materials with glass transition temperatures (T_g) around room temperature, i.e., 23⁰C, and/or with crystallinity above 10%.

The phrase "concentrated dispersion," "concentrated composite dispersion," or like terminology refers to a suspension, dispersion, emulsion, or slurry of kaolin and a matrix polymer in a liquid carrier medium, where the dispersion is concentrated by removal of a portion of the liquid carrier medium. The "liquid carrier medium" is generally being water.

The term "composite" or "filled polymer composite" refers to the mixture of kaolin and polymer. The mean particle size of the filler particles, "d₅o," of at least some filler particles can be below 1 micron (1 micrometer or 1 μm), and even can be below 250 nm (0.25 micrometer or 0.25 μm).

The term "shape factor" as used herein is a measure of an average value

(on a weight average basis) of the ratio of mean particle diameter to particle thickness for a population of particles of varying size and shape as measured using the electrical conductivity method, apparatus and equations described in United States Patent No. 5,576,617, which is incorporated herein by reference in its entirety.

The term "platy" refers to hydrous kaolin clays with shape factors of greater than about 40:1 as well as "hyperplaty" clays which refers to hydrous kaolin clays with shape factors of greater than about 70: 1.

The term "mean particle diameter" is defined as the diameter of a circle that has the same area as the largest face of the particle. The mean particle size, dso value, and other particle size properties referred to in the present application are measured in a well known manner by sedimentation of the particulate material in a fully dispersed condition in an aqueous medium using a SEDIGRAPH 5100 machine as supplied by Micromeritics Corporation. Such a machine provides measurements and a plot of the cumulative percentage by weight of particles having a size, referred to in the art as the "equivalent spherical diameter" (esd). The mean particle size dso is the value determined in this way of the particle esd at which there are 50 percent by weight of the particles that have an esd less than that dso value.

The "oxygen transmission rate," or "OTR," of the coatings used in the invention is measured according to ASTM D-3985-02 or any other suitable protocol using a MOCON® OXTRAN 2/21 or 2/61 module or Illinois Instruments 8001 or 8011 module and the following conditions: pressure of 1 atmosphere, a temperature of 23°C, and a relative humidity of 0 percent.

A "barrier coating composition" or "barrier coating mixture" includes a liquid containing suspended solids, which is used to apply the solids to a substrate. This includes a colloidal dispersion, suspension, emulsion and latex as they are conventionally defined. For example, by "colloidal dispersion or latex" is meant any dispersion or suspension of particles in liquid, the particles being of a size greater than molecular scale, e.g., about 0.001 to about 0.1 micron. An emulsion generally contains particles of about 0.05 to 1.0 microns, in liquid. A "suspension" generally contains particles of greater than 1.0 micron in liquid. A novel aspect of the present invention is that the barrier coating compositions provide a better dispersion of platy or hyperplaty kaolin in liquid at an unusually high solids content, e.g., between about 45 to about 60 percent solids as described in more detail below. According to this invention, once the "coating mixture" is dried, it is sometimes referred to as a "dried coating" or a "film".

The term "gas barrier" includes a barrier to oxygen, nitrogen, carbon dioxide and other gases.

"Oxygen permeability," as used herein, refers to a property of a material that describes the ease with which oxygen gas transmits through a film made of the material. The acrylic-kaolin composite films of the present invention have an oxygen permeability that is at least 10 times less than that of like films (of the same thickness) which contain no kaolin filler.

It should be noted that water is used as a dispersing and/or a liquid carrier medium. However, various other liquids which are water miscible or water compatible can also be used in conjunction with water. Examples of such solvents include, without any limitation, various water miscible alcohols, ethanol being preferred, ketones such as acetone, methyl ethyl ketone, esters such as butyl acetate or ethyl acetates, and the like. Preferably no other solvent is used with water.

The coating formulations and subsequent polymer-kaolin barrier coatings that are formed from them are unique in the following respects among others: 1. The dispersed polymer used is not elastomeric - (surprising that the dispersed polymer particles can deform to form the platy or hyperplaty barrier film);

2. The platy or hyperplaty kaolin additive has not been organically functional ized (which is typically done using an ion exchange process with organic cations);

3. The concentration of filler can be high (up to 60% relative to the total weight) also leading to large reductions in permeability and reduced drying costs.

Non-elastomeric acrylics suitably include those acrylics with T_g values less than 7O⁰C, preferably less than 35⁰C. "Acrylic" is a generic term denoting derivatives of acrylic and methacrylic acid, including acrylic esters and compounds containing nitrile and amide groups. Traditional monomers include: acrylic acid, methacrylic acid, itaconic acid, acrylamide, acrylonitrile and maleic anhydride; and acrylic esters such as ethyl, methyl, butyl, ethyl-hexyl acrylates and methacrylates. For the purposes of this invention, the term "acrylic" also includes copolymers of the above monomers with vinylics, styrenes, olefins such as ethylene, propylene, etc., and the like. Particularly preferred in some cases are styrene-acrylic copolymers.

The major classes of acrylics are based on pure acrylics, vinyl acrylics and styrene acrylics. These can be derived from acrylates, methacrylates, vinylics and styrenics and their various copolymers. There also exist other copolymers of these acrylics with monomers derived from acrylamides, methacrylamides, acrylonitrile, olefins such as ethylene, and the like. Particularly preferred acrylics include acrylate polymers and copolymers with acrylamide, styrene, vinyl esters and urethanes. Still more particularly preferred acrylics are self-crosslinking types that include hydroxyl groups, expressed as a hydroxyl number ranging from 1 to 50, preferably 10-40, most preferably 15-30. Standard methods for determining hydroxyl numbers are based upon the derivatization of the hydroxyl groups with phthalic or acetic anhydride. Excess reagent is hydrolyzed to acid which is titrated with standardized base and the hydroxyl number is calculated from the difference in titers between sample and blank.

Crosslinking emulsions were developed to improve the film properties, particularly chemical resistance, in selected applications. There are two- component crosslinking systems where one of the crosslinking components is added just before application of the dispersion. Alternatively, there are self- crosslinking (one pot) systems where all reactive components are present and long-term storage stable. The crosslinking reaction can be triggered by the evaporation of water upon drying, a change of pH, or by curing at elevated temperature, where the crosslinking reaction is faster, or reactive groups are de- blocked. Examples of suitable crosslinking systems are the reaction of aziridines with acid groups on the polymer backbone, the reaction of hydroxyl functionality on the backbone with post added isocyanates or melamines, the reaction of amines with epoxy functionality where either can be on the polymer backbone, the auto- oxidation of incorporated fatty acid groups, the self condensation of alkoxy-silane functionality, the self condensation of n-methylolacrylamide metal-ion coordination with backbone functional groups such as acetoacetoxy groups or acid groups, and the reaction of acetoacetoxy groups with amines or acetoacetoxy groups with unsaturated groups in a Michael reaction.

The polymer is in the form of a dispersion, latex, suspension or emulsion in water, or a mixture of water with a solvent prior to being mixed with the clay dispersion. Preferred non-elastomeric acrylics are acrylics such as DORESCO TAW4-39 and DORESCO TAW7-1 from Lubrizol Dock Resins. Particularly preferred acrylics are those suitable for coatings, such as ACRONAL coatings from BASF. Specific examples include ACRONAL NX4533, ACRONAL

NX4646, ACRONAL S728na and the like. Other commercially available acrylic polymers that may be employed in this invention include STYRONAL ND656 and EPOTAL XE21821, both from BASF Corp. Coating mixtures of the invention employing these polymers are specifically exemplified below.

Kaolin, also referred to as China Clay, or hydrous kaolin, is comprised predominantly of the mineral kaolinite, a hydrous aluminium silicate, together with small amounts of a variety of impurities. Particulate kaolin products find a variety of uses, including as pigments, fillers, and extenders for use in paint, plastics, polymers, and so forth.

For instance, kaolin has been used as an extender or pigment in paints, plastics and othercoating compositions. Kaolin pigments confer desirable physical and optical properties to such compositions. As flattening (or matting) agents, they help smooth the surfaces of the substrates to which they are applied. As opacifiers, they impart brightness, whiteness, gloss and other desirable optical properties. As extenders, they allow partial replacement of titanium dioxide and other more expensive pigments with minimal loss of whiteness or brightness.

Hyperplaty kaolin that is suitable for use in the composition of this invention is described in United States Patent Nos. 6,758,895; 7,208,039; 7,214,264 and 7,226,005, all of which are incorporated herein by reference in their entirety. Platy kaolin that is suitable for use in the composition of this invention is described in United States Patent Nos. 6,616,749; 6,814,796; 6,537,363; 6,610,137; 6,564,199; and 6,808,559, all of which are incorporated herein by reference in their entirety. Briefly, the high shape factor may be achieved by grinding mined kaolinitic clays until the desired shape factor is achieved. Any art recognized grinding method can be used with the present invention including but not limited to, for example, wet grinding using sand or ceramic media. For example, the kaolin may be prepared by light comminution, e.g., grinding or milling, of a coarse kaolin to give suitable delamination thereof. The comminution may be carried out by use of beads or granules of a ceramic or plastic, e.g., nylon, grinding or milling aid. Appropriate grinding energies will be readily apparent and easily calculated by the skilled artisan. Significant grinding energies may be necessary to attain desirable high shape factors, however kaolin crude selected for its natural platyness will grind to high shape factors in an energy range typically used to manufacture standard delaminated kaolin pigments that have lesser shape factors.

Crude kaolin or a high shape factor product obtained from grinding or milling may be refined to remove impurities and improve physical properties using well known procedures generally referred to as beneficiation processes. The kaolin may be treated by a known particle size classification procedure, screening and/or centrifuging, to obtain particles having a desired particle size distribution and d₅₀ value (as discussed above). Preferably, mined clays are suitably first degritted before they are subjected to grinding to achieve the desired shape factor.

Kaolin samples developed and provided by Imerys Pigments Inc. (USA) and Imerys Minerals Ltd. (UK), discussed in the description of Examples, were tested and found suitable for the barrier coating composition of this invention.

The barrier coating formulations of the invention may employ at least one or more than one suitable surfactant to reduce surface tension, and aid in dispersion. Surfactants include materials otherwise known as wetting agents, anti- foaming agents, emulsifiers, dispersing agents, leveling agents etc. Surfactants can be anionic, cationic and nonionic, and many surfactants of each type are available commercially. A suitable surfactant for inclusion in these compositions possesses a critical micelle concentration sufficiently low to ensure a dried barrier coating uncompromised by residual surfactant. In the event of an unfavorable interaction of the anionic emulsifier present in the latex dispersion, additional ionic additives should be kept to a minimum. This variable is eliminated where the surfactant or emulsifier is non-ionic. Increase in ionic concentration of the compositions, such as by the addition of a base to adjust pH, e.g., KOH, NH₄OH and NaOH, may cause agglomeration of the filler, which adversely affects permeability reduction.

Desirable surfactants may include SURFYNOL^® PSA 336 or SURFYNOL 104E (Air Products, Inc.), POLYSTEP B27 (Stepan Company), SIL WET^® L-77 (OSI Specialties, Inc.), and ZONYL FSP and 8952 (DuPont Performance Chemicals and Intermediates). The amount and number of surfactants added to the coating composition will depend on the particular surfactant(s) selected, but should be limited to the minimum amount of surfactant that is necessary to achieve wetting of the substrate while not compromising the performance of the dried barrier coating. For example, typical surfactant amounts can be less than or equal to about 15% by weight of the dried barrier coating.

Other additives that are of particular use in the compositions of this invention are thickeners. Any of the art recognized thickeners can be used in this invention. A few of the examples of thickeners include, without any limitation, a variety of polyethylene glycols and their copolymers as well as a variety of acrylic copolymers. Specific commercially available thickeners are sold under the name ACUSOL thickeners from Rohm & Haas, which also serve as opacifiers to brighten the compositions of this invention. Specific commercially available grades include ACUSOL 880, which is a PEG copolymer and ACUSOL 882 which is an acrylic copolymer. Both of these thickeners are also useful as nonionic associative rheology modifiers.

The dispersions may also include additional additives such as emulsifiers, biocides, colloidal dispersants, anti-foaming agents, dispersing agents, wetting agents, leveling agents, thickeners, absorbers and getters. Other optional components of the coating mixture include conventional agents to adjust pH, such as bases, e.g., NH₄OH, NaOH or KOH; or acids, e.g., acetic acid, citric acid or glycine provided that care is taken to avoid agglomeration.

In one embodiment of this invention, the aqueous barrier coating composition of this invention is concentrated by evaporating off selectively a portion of water in order to increase the total solids content at least by about 5 percent. Any art recognized concentration methods can be used with the present invention including but not limited to, for example, evaporation and/or condensation methods or distillation at atmospheric and/or below atmospheric pressure conditions. In a condensation approach the composition is suitably subjected to an elevated temperature, so as to evaporate-off selectively a portion of water to increase the solids content of the dispersion. In a distillation method, the water is removed by distillation either under atmospheric pressure conditions or at reduced pressure at a lower temperature. Similarly, the formulation can also be subjected to the condensation step thereby a portion of water is removed selectively. The purpose is to selectively increase the solids content of the dispersion. The liquid may be evaporated off by heating; preferably at a temperature of from about 8O⁰C to about 100⁰C for about 70 to about 100 minutes while stirring until about 1% to about 30% of the liquid carrier evaporates.

The dispersions are typically condensed such that the solids content of the dispersion increases by at least 20 percent or even more preferably at least 30 percent or most preferably at least 50 percent. The concentrated dispersion generally includes at least about 25 weight percent solids, preferably from about 30 to about 60 weight percent solids. Before it is concentrated, the dispersion typically includes from about 15 to 20 weight percent solids. It is unexpected that the dispersion may be concentrated by evaporation without causing the formulation to gel. For example, many filler materials, such as kaolin, form gels at relatively low solids content, and the solids content of the silicate component often limits the final solids content of the barrier coating. As noted above, the compositions of this invention can have a relatively high total solids content on a weight basis as compared with known nanocomposite barrier compositions and a relatively low solids content as compared with clay coating compositions.

After coating, the applied film mold may be dried at a selected temperature, e.g., room temperature or greater than room temperature. The selection of the drying temperature, relative humidity, and convective air flow rates depends on the desired time for drying; that is, reduced drying times may be achieved at elevated air temperatures, lower relative humidity and higher rates of air circulation over the drying coating surface. One of skill in the art can readily adjust the drying conditions as desired.

The dried coatings exhibit a surprising reduction in permeability compared to the prior art and particularly compared to unfilled polymers. As evidenced in the Examples below, reductions in permeability caused by the dried coatings of this invention are shown to be from about 25 fold to 10,000 fold and even higher relative to the unfilled polymers alone. The evaluation of gas permeability of the coatings of the present invention is further described in detail by specific Examples 1-22.

EXAMPLES

In the following examples, non-elastomeric acrlylic-kaolin barrier coating compositions are prepared and applied to suitable polyester (PET) or polypropylene (PP) film substrates and then are tested for oxygen transmission rate. The barrier coating dispersions are prepared in an aqueous medium with a styrene-acrylic resin, (Acronal NX4646 and other resins) and kaolin clay samples (provided by Imerys) as the filler. EXPERIMENTAL PROCEDURES Oxygen Transmission Rate (OTR) Testing

Films and coated substrates are tested for oxygen transmission rate using a Mocon OXTRAN 2/21 or 2/61 module or an Illinois Instrument 8001 or 8011 module at 23⁰C, 0% RH, and 1 atm. The samples are loaded onto the modules and conditioned for 2 hours prior to testing for oxygen. Once equilibrium is reached, an OTR is reported in units of cc/m² day atm.

Thickness Measurements All thickness calculations are based on the weight of the coating, and an assumed density. For the purposes of the present invention, the density for the polymer phase is assumed to be 1.2 gm/cc in all cases, even though it is recognized that each polymer has a different density. The density of the non- elastomeric polymer-kaolin composition was estimated using a rule of mixtures, and an assumed density of the clay of 2.6 gm/cc.

The thickness of the coating on a substrate is measured after the OTR is reported. Each sample is removed from the Mocon module and a circle of specified size is cut from the sample. The cut circle is weighed. The weight of the coating is obtained from subtracting the weight of the uncoated circle, and the thickness calculated from the size of the circle and weight of the coating. For coating thickness less than 5 microns, the thickness is measured using an optical profilometer. The thickness of the film is reported in millimeters and used to calculate the permeability of the film.

The permeability of the coatings is calculated as follows:

Permeability of barrier coating

5 where Xi is the barrier coating thickness; X₂ is substrate thickness, Px₂ is permeability of the substrate, and OTR is oxygen transmission rate measured for the barrier coating. The reduction in permeability is calculated as follows:

, ~ Reduction in

'" permeability

The benefit of obtaining the permeability of the coating versus the OTR of the sample is that permeability reports the OTR at a specified thickness. 15 Therefore, coatings with different thicknesses can be compared directly. OTR units are cc/m² day at 1 atmosphere, 0% relative humidity at 23⁰C. Permeability units are cc mm/m² day at 1 atmosphere, 0% relative humidity at 23⁰C.

EXAMPLES 1-7 0 The following Examples 1-7 illustrate the effect of acid pre-treatment.

The results of Examples 1-7 are summarized in Table 1 below.

Example 1 (NB# 38764-22-31

In a 4 oz jar with a stir bar, place 17.5g of Kaolin clay (XP6100DF, 5 Imerys, 30%) and 0.04 g Acumer 9300 (Rohm & Haas, 44%) and allow the clay to stir overnight resulting in 30% slurry of Kaolin. To this slurry, add 8.39 g of glycine (Hawk Creek Lab, 20%) and stir for 60 minutes.

In an 8 oz jar with a stir bar, place 16.02 g of Acronal NX4646 (BASF, 0 50.4%) and 33.09 g of de-ionized water. After 30 minutes of stirring, add the Kaolin slurry to the polymer mixture. To the resulting solution, add 0.04 g of Surfynol PSA-336 (Air Products, 50%) and stir for 15 minutes.

The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-80⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 53% solids.

The solution is hand coated on 92 ga BOPP film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 1109 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 5.2 micron film is 8.2 cc mm/m2 day atm @ 23⁰C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 5.6 times.

Example 2 fNB# 38764-33-lb) In a 4 oz jar with a stir bar, place 17.5 g of Kaolin clay (XP6100DF,

Imerys, 30%), 10.0 g of de-ionized water and 14.0 g of citric acid (Fisher Scientific, 20%). Stir the resulting 30% slurry for 24 hours.

In an 8 oz jar with a stir bar, place 13.79 g of Acronal NX4646 (BASF, 50.4%), g of 0.12 g Polystep B27 (Stepan Company, %) , and 19.71 g of de- ionized water. After 30 minutes of stirring, add the Kaolin slurry to the polymer mixture. To the resulting solution, add 0.04 g of Surfynol PSA-336 (Air Products, 50%) and stir for 15 minutes.

The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-80⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 47% solids.

The solution is hand coated on 92 ga BOPP film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 41.6 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 4.2 micron film is 0.18 cc mm/m2 day atm @ 23°C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 258 times.

Example 3 (NB# 38764-33-3a) In a 4 oz jar with a stir bar, place 35.0 g of Kaolin clay (XP6100DF,

Imerys, 30%),20 g of de-ionized water and 16.8 g of citric acid (Fisher Scientific, 20%) and stirred for 24 hours.

In an 8 oz jar with a stir bar, place 27.58 g of Acronal NX4646 (BASF, 50.4%), 0.08 g of Polystep B27 (Stepan Company, 50%), 0.04 g of Surfynol 104E (Air Products, 50%) and 55.16 g of de-ionized water. After 30 minutes of stirring, add the Kaolin slurry to the mixture. To the resulting solution, add 0.08 g of Surfynol PSA-336 (Air Products, 50%) and stir for 15 minutes.

The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-8O⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 45% solids.

The solution is hand coated on 92 ga BOPP film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 350 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 4.4 micron film is 1.74 cc mm/m2 day atm @ 23°C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 26.7 times.

Example 4 (NB# 38764-38-2)

In a 4 oz jar with a stir bar, place 18.55 g of Kaolin clay (XP01-6100, Imerys, 56.6%), 37.83 g of de-ionized water and 28.0 g of citric acid (Fisher Scientific, 20%) and stir for 60 minutes. In an 8 oz jar with a stir bar, place 27.78 g of Acronal NX4646 (BASF, 50.4%), 0.28 g of Polystep B27 (Stepan Company, 50%), and 37.83 g of de- ionized water. Stir for 30 minutes.

The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-80⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 41% solids.

The solution is hand coated on 92 ga BOPP film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 785 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 4.0 micron film is 5.8 cc mm/m2 day atm @ 23⁰C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 8 times.

Example 5 (NB# 38764-43-H

In a 4 oz jar with a stir bar, place 25.0 g of de-ionized water. With the water stirring, add 17.5 g of Kaolin clay (XP01-6100, Imerys, 30%) and 0.04 g of Acumer 9300 (Rohm & Haas, 44%) and allow the clay to stir overnight. To this slurry, add 2.79 g of acetic acid (Fisher Scientific, 20%) and stirred for 60 minutes.

In an 8 oz jar with a stir bar, place 18.24 g of Acronal NX4646 (BASF, 50.4%), 0.12 g of Polystep B27 (Stepan Company, 50%), 0.04 g of Surfynol 104E (Air Products, 50%) and 11.47 g of de-ionized water. After 30 minutes of stirring, add the Kaolin slurry to the mixture. To the resulting solution, add 0.04 g of Surfynol PSA-336 (Air Products, 50%) and stir for 15 minutes. The resulting formulation is 20% solids.

The solution is hand coated on 92 ga BOPP film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 1120 cc/m2 day atm @ 23⁰C and 0% relative humidity and a permeability of the 1.9 micron film is 19.5 cc mm/m2 day atm @ 23°C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 2.4 times.

Example 6 (NB# 38764-74-2a) In a 4 oz jar with a stir bar, place 18.65 g of de-ionized water. With the water stirring, add 35.0 g of Kaolin clay (XP01-6100, Imerys, 30%) and allow the clay to stir overnight. To this slurry add 17.87 g of citric acid (Fisher Scientific, 20%) and 5.86 g of acetic acid (Fisher Scientific, 20%) and stir for 24 hours.

In an 8 oz jar with a stir bar, place 44.73 g of de-ionized water, 0.40 g of

Acusol 880 (Rohm & Haas, 35.2%) and 0.79 g of Acusol 882 (Rohm & Haas, 17.7%) and stir overnight. To this solution, add 26.7 g of Acronal NX4646 (BASF, 50.4%) and 0.28 g of Polystep B27 (Stepan Company, 50%). After 30 minutes of stirring, add the Kaolin slurry to the polymer and stir for 15 minutes.

The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-8O⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 40% solids.

The solution is hand coated on 92 ga PET film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 36.6 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 3.9 micron film is 0.22 cc mm/m2 day atm @ 23°C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 211 times.

Example 7 (NB# 38764-75^

In a 4 oz jar with a stir bar, place 20.0 g of de-ionized water. With the water stirring, add 35.0 g of Kaolin clay (XP01-6100, Imerys, 30%) and allow the clay to stir overnight. To this slurry add 17.87 g of citric acid (Fisher Scientific, 20%) and stir for 24 hours. In an 8 oz jar with a stir bar, place 46.64 g of de-ionized water, 0.43 g of Acusol 880 (Rohm & Haas, 35.2%) and 0.86 g of Acusol 882 (Rohm & Haas, 17.7%) and stir overnight. To this solution, add 29.2 g of Acronal NX4646 (BASF, 50.4%) and 0.28 g of Polystep B27 (Stepan Company, 50%). After 30 minutes of stirring, add the Kaolin slurry to the polymer and stir for 15 minutes.

The solution is hand coated on 92 ga PET film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 69 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 3.9 micron film is 0.86 cc mm/m2 day atm @ 23°C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 54 times.

Table 1 - Adjust Kaolin Treatment

Notes:

Examples 1-7

Polymer phase is Acronal NX4646.

Kaolin clay is XP01-6100 or a comparable version of XP6100DF with dispersant Acumer

9300.

All formulations made at 20% solids and concentrated to 32-49% solids.

OTR is oxygen transmission rate in units of cc/m2 day atm @ 23°C , 0% RH.

Permeability is oxygen permeability in units of cc mm/m2 day atm @ 23°C , 0% RH.

Times reduction is compared to the permeability of unfilled Acronal NX4646 of 46.4 cc mm/m2 day atm @ 23⁰C , 0% RH. It is seen in Table 1 that the barrier properties of the compositions can be greatly enhanced by the judicious choice of acid treatment. Other suitable dispersants may include one or more of the dispersants listed in Table IA.

Table IA - Dispersants

EXAMPLES 8-16

The following Examples 8-16 illustrate the effect of concentrating the mixed polymer and kaolin dispersions prior to forming a barrier coating.

The results of Examples 8-16 are summarized in Table 2 below.

Example 8 (NB# 38764-67-Ic^

In a 4 oz jar with a stir bar, place 20.0 g of de-ionized water. With the water stirring, add 35.0 g of Kaolin clay (XPO 1-6100, Imerys, 30%) and allow the clay to stir overnight. To this slurry add 22.34 g of citric acid (Fisher Scientific, 20%) and stir for 24 hours.

In an 8 oz jar with a stir bar, place 44.37 g of de-ionized water, 0.40 g of Acusol 880 (Rohm & Haas, 35.2%) and 0.79 g of Acusol 882 (Rohm & Haas, 17.7%) and stir overnight. To this solution, add 27.1 g of Acronal NX4646 (BASF, 50.4%) and 0.28 g of Polystep B27 (Stepan Company, 50%). After 30 minutes of stirring, add the Kaolin slurry to the polymer and stir for 15 minutes. The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-80⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 45% solids.

The solution is hand coated on 92 ga PET film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 1.7 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 4.4 micron film is 0.008 cc mm/m2 day atm @ 23°C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 5800 times.

Example 9 fNB# 38764-72-la)

In a 4 oz jar with a stir bar, place 20.0 g of de-ionized water. With the water stirring, add 35.0 g of Kaolin clay (XP01-6100, Imerys, 30%) and allow the clay to stir. To this slurry add 22.34 g of citric acid (Fisher Scientific, 20%) and stir for 24 hours.

In an 8 oz jar with a stir bar, place 44.77 g of de-ionized water, 0.40 g of Acusol 880 (Rohm & Haas, 35.2%) and 0.79 g of Acusol 882 (Rohm & Haas, 17.7%) and stir overnight. To this solution, add 26.7 g of Acronal NX4646 (BASF, 50.4%) and 0.28 g of Polystep B27 (Stepan Company, 50%). After 30 minutes of stirring, add the Kaolin slurry to the polymer and stir for 15 minutes.

The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-80⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 44% solids.

The solution is hand coated on 92 ga PET film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 1.9 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 4.3 micron film is 0.008 cc mm/m2 day atm @ 23⁰C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 5800 times. Example 10 fNB# 38764-75- Ia)

The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-8O⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 43% solids.

The solution is hand coated on 92 ga PET film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 4.6 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 4.2 micron film is 0.02 cc mm/m2 day atm @ 23°C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 2320 times.

Example 11 (NB# 38764-67- Ic)

In an 8 oz jar with a stir bar, place 44.37 g of de-ionized water, 0.40 g of Acusol 880 (Rohm & Haas, 35.2%) and 0.79 g of Acusol 882 (Rohm & Haas, 17.7%) and stir overnight. To this solution, add 27.1 g of Acronal NX4646 (BASF, 50.4%) and 0.28 g of Polystep B27 (Stepan Company, 50%). After 30 minutes of stirring, add the Kaolin slurry to the polymer and stir for 15 minutes.

The solution is hand coated on 92 ga PET film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 2.6 cc/m2 day atm @ 23⁰C and 0% relative humidity and a permeability of the 4.0 micron film is 0.011 cc mm/m2 day atm @ 23⁰C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 4218 times.

Example 12 (NB# 38764-73-2a) In a 4 oz jar with a stir bar, place 20.0 g of de-ionized water. With the water stirring, add 35.0 g of Kaolin clay (XP01-6100, Imerys, 30%) and allow the clay to stir. To this slurry add 22.34 g of citric acid (Fisher Scientific, 20%) and stir for 24 hours.

In an 8 oz jar with a stir bar, place 44.77 g of de-ionized water, 0.40 g of

The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-80⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 38% solids.

The solution is hand coated on 92 ga PET film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 1.2 cc/m2 day atm @ 23⁰C and 0% relative humidity and a permeability of the 3.7 micron film is 0.005 cc mm/m2 day atm @ 23°C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 5156 times.

Example 13 (NB# 38764-80-2^

In an 8 oz jar with a stir bar, place 44.84 g of de-ionized water, 0.40 g of Acusol 880 (Rohm & Haas, 35.2%) and 0.79 g of Acusol 882 (Rohm & Haas, 17.7%) and stir overnight. To this solution, add 26.63 g of Acronal NX4646 (BASF, 50.4%) and 0.28 g of Polystep B27 (Stepan Company, 50%). After 30 minutes of stirring, add the Kaolin slurry to the polymer and stir for 15 minutes.

The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-80⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 37% solids.

The solution is hand coated on 92 ga PET film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 2.3 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 3.7 micron film is 0.008 cc mm/m2 day atm @ 23°C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 5800 times.

Example 14 (NB# 38764-72-2a)

In a 4 oz jar with a stir bar, place 20.0 g of de-ionized water. With the water stirring, add 35.0 g of Kaolin clay (XPOl -6100, Imerys, 30%) and allow the clay to stir. To this slurry add 22.34 g of citric acid (Fisher Scientific, 20%) and stir for 24 hours. In an 8 oz jar with a stir bar, place 44.87 g of de-ionized water, 0.40 g of Acusol 880 (Rohm & Haas, 35.2%) and 0.79 g of Acusol 882 (Rohm & Haas, 17.7%) and stir overnight. To this solution, add 26.6 g of Acronal NX4646 (BASF, 50.4%) and 0.28 g of Polystep B27 (Stepan Company, 50%). After 30 minutes of stirring, add the Kaolin slurry to the polymer and stir for 15 minutes.

The resulting formulation is fhen heated uncovered in a water bath with an internal temperature of 75-80⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 36% solids.

The solution is hand coated on 92 ga PET film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 3.6 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 3.5 micron film is 0.014 cc mm/m2 day atm @ 23°C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 3314 times.

Example 15 (NB# 38764-63-Ia^

In a 4 oz jar with a stir bar, place 20.0 g of de-ionized water. With the water stirring, add 35.0 g of Kaolin clay (XPO 1-6100, Imerys, 30%) and allow the clay to stir. To this slurry add 22.34 g of citric acid (Fisher Scientific, 20%) and stir for 24 hours.

In an 8 oz jar with a stir bar, place 45.06 g of de-ionized water, 27.6 g of Acronal NX4646 (BASF, 50.4%) and 0.28 g of Polystep B27 (Stepan Company, 50%). After 30 minutes of stirring, add the Kaolin slurry to the polymer and stir for 15 minutes.

The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-80⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 35% solids. The solution is hand coated on 92 ga PET film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 4.3 cc/m2 day atm @ 23⁰C and 0% relative humidity and a permeability of the 3.4 micron film is 0.016 cc mm/m2 day atm @ 23°C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 2900 times.

Example 16 (NB#38764-66- Ia)

The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-80⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 29% solids.

The solution is hand coated on 92 ga PET film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 7.7 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 2.8 micron film is 0.026 cc mm/m2 day atm @ 23⁰C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 1785 times. Table 2 - Adjust Final Solid Content of Acrylic Kaolin Formulation

Notes:

Examples 8-16.

Polymer phase is Acronal NX4646.

Kaolin Clay treatment 5x of 25% citric acid for 24 hrs.

All formulations made at 20% solids and concentrated to 29-45% solids.

Clay used was XPO 1-6100.

OTR is oxygen transmission rate in units of cc/m2 day atm @ 23⁰C , 0% RH.

Times reduction is compared to the permeability of unfilled Acronal

NX4646 of 46.4 cc mm/m2 day atm @ 23⁰C , 0% RH.

EXAMPLES 17-18. 15 and 22

The following Examples 17-18 further illustrate the effect of selecting an appropriate platy or hyperplaty kaolin. Some suitable Kaolins are listed in Table

3A.

Table 3A - Clay

Example 17fNB# 38764-34-2)

In a 4 oz jar with a stir bar, place 10.0 g of de-ionized water. With the water stirring, add 21.17 g of Kaolin clay (XP6100DF, Imerys, 49.6%) and 27.9 g of citric acid (Fisher Scientific, 20%) and stir for 24 hours.

In an 8 oz jar with a stir bar, place 27.6 g of Acronal NX4646 (BASF, 50.4%), 63.4 g of de-ionized water and 0.28 g of Polystep B27 (Stepan Company, 50%). After 30 minutes of stirring, add the Kaolin slurry and stir for 15 minutes.

The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-80⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 58% solids.

The solution is hand coated on 92 ga BOPP film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 403 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 5.3 micron film is 2.8 cc mm/m2 day atm @ 23⁰C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 16.6 times.

Example 18 fNB# 38764-54-2a)

In a 4 oz jar with a stir bar, place 10.0 g of de-ionized water. With the water stirring, add 17.5 g of Kaolin clay (XP07-6140, Imerys, 30%) and 11.17 g of citric acid (Fisher Scientific, 20%) and stir for 24 hours.

In an 8 oz jar with a stir bar, place 13.8 g of Acronal NX4646 (BASF,

50.4%), 22.53 g of de-ionized water and 0.14 g of Polystep B27 (Stepan Company, 50%). After 30 minutes of stirring, add the Kaolin slurry and stir for 15 minutes. The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-80⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 45% solids.

The solution is hand coated on 92 ga BOPP film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 106 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 4.4 micron film is 0.49 cc mm/m2 day atm @ 23°C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 95 times.

The results are seen in Examples 17, 18 are summarized and compared with Examples 2, 15 and 4 in Table 3B below.

Table 3B - Adjust Kaolin Type

Notes:

Examples 2, 17-18, 15 and 4.

Polymer phase is Acronal NX4646.

Clay treatment 5x of 25% citric acid for 24 hrs.

All formulations made at 20% solids and concentrated to 35-45% solids.

OTR is oxygen transmission rate in units of cc/m2 day atm @ 23°C , 0% RH.

Times reduction is compared to the permeability of unfilled Acronal NX4646 of 46.4 cc mm/m2 day atm @ 23⁰C , 0% RH.

It was found during the course of investigation that best results were observed if the kaolin slurry was used to make the formulation within 48 hours (or less) of forming the slurry. EXAMPLES 19-21

The following Examples demonstrate the effect of polymer selection and are compared with Example 15 in Table 4 below.

Example 19 (NB# 38764-52-1)

In a 4 oz jar with a stir bar, place 20.0 g of de-ionized water. With the water stirring, add 17.5 g of Kaolin clay (XP01-6100, Imerys, 30%) and 13.96 g of citric acid (Fisher Scientific, 20%) and stir for 24 hours.

In an 8 oz jar with a stir bar, place 13.97 g of Epotal XE21821 (BASF,

50.4%), 0.12 g of Polystep B27 (Stepan Company, 50%) and 9.57 g of de-ionized water. After 30 minutes of stirring, add the Kaolin slurry to the mixture and stir for 15 minutes.

The solution is hand coated on 92 ga BOPP film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 44 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 3.7 micron film is 0.17 cc mm/m2 day atm @ 23⁰C and 0% relative humidity. This permeability is reduced from the unfilled polymer by times.

Example 20 (NB# 38764-61-1 a)

In a 4 oz jar with a stir bar, place 20.0 g of de-ionized water. With the water stirring, add 35.0 g of Kaolin clay (XP01-6100, Imerys, 30%) and 22.34 g of citric acid (Fisher Scientific, 20%) and stir for 24 hours.

In an 8 oz jar with a stir bar, place 27.99 g of Styronal ND656 (BASF,

50.4%), 0.28 g of Polystep B27 (Stepan Company, 50%) and 44.67 g of de- ionized water. After 30 minutes of stirring, add the Kaolin slurry to the mixture and stir for 15 minutes.

The resulting formulation is then heated uncovered in a water bath with an internal temperature of 75-8O⁰C until the desired solids is reached. The concentrated solution is cooled while stirring resulting in 46% solids.

The solution is hand coated on 92 ga BOPP film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 103 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 4.5 micron film is 0.49 cc mm/m2 day atm @ 23⁰C and 0% relative humidity. This permeability is reduced from the unfilled polymer by times.

Example 21 fNB# 38764-6 l-3a) In a 4 oz jar with a stir bar, place 20.0 g of de-ionized water. With the water stirring, add 35.0 g of Kaolin clay (XP01-6100, Imerys, 30%) and 22.34 g of citric acid (Fisher Scientific, 20%) and stir for 24 hours.

In an 8 oz jar with a stir bar, place 27.17 g of Acronal S728na (BASF, 50.4%), 0.28 g of Polystep B27 (Stepan Company, 50%) and 45.49 g of de- ionized water. After 30 minutes of stirring, add the Kaolin slurry to the mixture and stir for 15 minutes.

The solution is hand coated on 92 ga BOPP film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 606 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 3.6 micron film is 3.4 cc mm/m2 day atm @ 23°C and 0% relative humidity. This permeability is reduced from the unfilled polymer by times.

Table 4 - Vary Polymer with Kaolin Clay

Notes:

Examples 15, 19-21.

Kaolin (XPO 1-6100) treatment 5x of 25% citric acid for 24 hours.

OTR is oxygen transmission rate in units of cc/m2 day atm @ 23⁰C , 0% RH.

Permeability is oxygen permeability in units of cc mm/m2 day atm @ 23°C , 0%

RH.

Times reduction is compared to the permeability of unfilled polymer.

EXAMPLE 22

The following Example 22 demonstrates further the beneficial effect of concentrating the coating composition prior to making the barrier film.

Example 22 (NB# 38764-21-n

In a 4 oz jar with a stir bar, place 75.18 g of Kaolin clay (XP6100, Imerys, 20%) and 24.1 g of glycine (Hawk Creek Lab, 20%) and stirred for 24 hours.

In an 8 oz jar with a stir bar, place 45.8 g of Acronal S7 (BASF28na, 50.4%), 3.07 g of de-ionized water. After 30 minutes of stirring, add the Kaolin slurry to the mixture and stir for 15 minutes. To the resulting solution, add 0.04 g of Surfynol PSA-336 (Air Products, 50%) and stir for 15 minutes. The solution is hand coated on 92 ga BOPP film using a #15 mayer rod and air dried. The coated film resulted in an oxygen transmission rate of 1158 cc/m2 day atm @ 23°C and 0% relative humidity and a permeability of the 2.8 micron film is 4.7 cc mm/m2 day atm @ 23⁰C and 0% relative humidity. This permeability is reduced from the unfilled polymer by 9.8 times. The results of Example 22 are summarized in Table 5 below, wherein it is seen the film exhibits less barrier than films formed from compositions that were concentrated prior to being formed into a film.

Table 5 - Formulations at higher solid content - no concentration step

There is thus provided an aqueous barrier coating composition in the form of a dispersion including: (a) water; (b) an acrylic matrix polymer; (c) a platy or hyperplaty kaolin having an average shape factor of at least about 40:1 the filler being pre-treated with acid prior to being combined with the acrylic matrix polymer, the composition optionally including a dispersant and/or a thickener and being further characterized in that: (i) the composition has a solids content of from 20 to 70 percent by weight; (ii) the composition has a weight ratio of acrylic matrix polymeπkaolin filler of from 4:1 to 0.75:1; and (iii) a film formed from the composition exhibits at least 25-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer. In many cases, the dispersion has a solids content of at least 25 percent by weight or a solids content of at least 30 percent by weight.

Typically, the weight ratio of acrylic matrix polymerkaolin additive is from 3:1 to 1:1 such as a weight ratio of acrylic matrix polymeπkaolin filler is from 2.5: 1 to 1.5: 1. In most cases, the platy or hyperplaty kaolin filler has an average shape factor of at least 50: 1 such as at least 60: 1 ; at least 70: 1 ; at least about 80: 1 ; at least about 90: 1 ; or at least about 100: 1. Generally speaking, the kaolin filler has an average shape factor of from 40:1 to 150:1 as well as a mean particle size (dso) ranging from about 0.1 μm to about 2 μm. More typically, the platy or hyperplaty kaolin filler has a mean particle size (dso) ranging from about 0.25 μm to about 1.5 μm.

In preferred methods of preparing the aqueous compositions, the composition is concentrated by evaporating off a portion of water in order to increase the total solids content by at least 20 percent such as by at least 50 percent or by at least 100 or 150 percent in some preferred embodiments. So also, the method advantageously includes: (a) providing a first aqueous dispersion containing an acrylic matrix resin; (b) providing a second aqueous dispersion containing an acid-treated platy or hyperplaty kaolin filler having an average shape factor of at least about 40:1 ; (c) admixing the first dispersion and the second dispersion of acid-treated kaolin; and (d) concentrating the admixed first and second dispersions by evaporating water therefrom such that solids content of the admixed dispersion is increased by at least 20 percent. The kaolin may be treated with an acid chosen from acetic acid, citric acid or glycine or a combination thereof.

In a further aspect of the invention, there is provided an acrylic barrier film derived from an aqueous coating composition comprising (a) water; (b) an acrylic matrix polymer; (c) a kaolin filler having an average shape factor of at least about 40:1 which has been pre-treated with acid prior to combination with said matrix polymer, the composition also containing a dispersant or a thickener and being further characterized in that: (i) the composition has a solids content of from 20 to 70 percent by weight; and (ii) the composition has a weight ratio of acrylic matrix polymeπkaolin filler of from 4:1 to 0.75:1, wherein the film exhibits at least 25- fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer. The film preferably exhibits at least 50-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer or still more preferably at least 100-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer or at least 250, 500 or 1000-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer. At least 2,000-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer is readily achieved as is at least 4,000-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer. In general, preferred films exhibit from 25-fold to 10,000-fold reduction in permeability as compared with a like film formed of said acrylic matrix polymer. The films usually have a platy clay or hyperplaty clay content of from 20 weight percent to 60 weight percent such as a clay content of from 25 weight percent to 40 weight percent as well as a thickness of at least 1 micron. A thickness of at least 2 microns is somewhat typical. In most cases the gas barrier films of this invention have a thickness of from 0.5 micron to 20 microns.

While the invention has been described in connection with numerous embodiments, modifications of those embodiments within the spirit and scope of the present invention will be readily apparent to those of skill in the art. The invention is defined in the appended claims.

Claims

WHAT IS CLAIMED IS:

1. An aqueous barrier coating composition in the form of a dispersion comprising:

(a) water;

(b) an acrylic matrix polymer;

(c) a kaolin filler having an average shape factor of at least about 40:1 the filler being pre-tereated with acid prior to being combined with the acrylic matrix polymer, the composition optionally including a dispersant and/or a thickener and being further characterized in that:

(i) the composition has a solids content of from 20 to 70 percent by weight;

(ii) the composition has a weight ratio of acrylic matrix polymeπkaolin filler of from 4:1 to 0.75:1; and

(iii) a film formed from the composition exhibits at least 25-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer.

2. The aqueous barrier coating composition according to Claim 1, having a solids content of at least 25 percent by weight.

3. The aqueous barrier coating composition according to Claim 1, having a solids content of at least 30 percent by weight.

4. The aqueous barrier coating composition according to Claim 1, wherein the weight ratio of acrylic matrix polymeπkaolin filler is from 3:1 to 1:1.

5. The aqueous barrier coating composition according to Claim 1, wherein the weight ratio of acrylic matrix polymeπkaolin filler is from 2.5:1 to 1.5:1.

6. The aqueous barrier coating composition according to Claim 1, wherein the kaolin filler has an average shape factor of at least 50:1.

7. The aqueous barrier coating composition according to Claim 1, wherein the kaolin filler has an average shape factor of at least 60:1.

8. The aqueous barrier coating composition according to Claim 1, wherein the kaolin filler has an average shape factor of at least 70:1.

9. The aqueous barrier coating composition according to Claim 1, wherein the kaolin filler has an average shape factor of at least about 80: 1.

10. The aqueous barrier coating composition according to Claim 1, wherein the kaolin filler has an average shape factor of at least about 90: 1.

11. The aqueous barrier coating composition according to Claim 1, wherein the kaolin filler has an average shape factor of at least about 100: 1.

12. The aqueous barrier coating composition according to Claim 1, wherein the kaolin filler has an average shape factor of from 40:1 to 150:1.

13. The aqueous barrier coating composition according to Claim 1, wherein the kaolin filler has a mean particle size (ds₀) ranging from about 0.1 μm to about 2 μm.

14. The aqueous barrier coating composition according to Claim 1, wherein the kaolin filler has a mean particle size (dso) ranging from about 0.25 μm to about 1.5 μm.

15. The aqueous barrier coating composition according to Claim 1, wherein the composition is concentrated by evaporating off a portion of water in order to increase the total solids content by at least 20 percent.

16. The aqueous barrier coating composition according to Claim 1, wherein the composition is concentrated by evaporating off a portion of water in order to increase the total solids content by at least 50 percent.

17. The aqueous barrier coating composition according to Claim 1, wherein the composition is concentrated by evaporating off a portion of water in order to increase the total solids content by at least 100 percent.

18. The aqueous barrier coating composition according to Claim 1, , wherein the composition is concentrated by evaporating off a portion of water in order to increase the total solids content by at least 20 and up to 150 percent.

19. A method of making a barrier coating composition comprising the steps of:

(a) providing a first aqueous dispersion containing an acrylic matrix resin;

(b) providing a second aqueous dispersion containing an acid-treated kaolin filler having an average shape factor of at least about 40:1;

(c) admixing the first dispersion and the second dispersion of acid-treated kaolin; and (d) concentrating the admixed first and second dispersions by evaporating water therefrom such that solids content of the admixed dispersion is increased by at least 20 percent.

20. The method according to Claim 19, wherein the kaolin is treated with an acid chosen from acetic acid, citric acid or glycine or a combination thereof.

21. The method according to Claim 19, wherein the step of concentrating the admixed dispersion is effective to increase the solids content of the admixture by at least 50%.

22. The method according to Claim 19, wherein the step of concentrating the admixed dispersion is effective to increase the solids content of the admixture by at least 100%.

23. The method according to Claim 19, wherein the step of concentrating the admixed dispersion is effective to increase the solids content of the admixture by up to 150%.

24. An acrylic barrier film derived from an aqueous coating composition comprising (a) water; (b) an acrylic matrix polymer; (c) a kaolin filler having an average shape factor of at least about 40:1 which has been pre-treated with acid prior to combination with said matrix polymer, the composition also containing a dispersant or a thickener and being further characterized in that: (i) the composition has a solids content of from 20 to 70 percent by weight; and (ii) the composition has a weight ratio of acrylic matrix polymeπkaolin filler of from 4: 1 to 0.75:1, wherein the film exhibits at least 25-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer.

25. The barrier film according to Claim 24, wherein the film exhibits at least 50-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer.

26. The barrier film according to Claim 24, wherein the film exhibits at least 100-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer.

27. The barrier film according to Claim 24, wherein the film exhibits at least 250-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer.

28. The barrier film according to Claim 24, wherein the film exhibits at least 500-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer.

29. The barrier film according to Claim 24, wherein the film exhibits at least 1, 000-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer.

30. The barrier film according to Claim 24, wherein the film exhibits at least 2,000-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer.

31. The barrier film according to Claim 24, wherein the film exhibits at least 4,000-fold reduction in oxygen permeability as compared with a like film formed of said acrylic matrix polymer.

32. The barrier film according to Claim 24, wherein the film exhibits from 25-fold to 10,000-fold reduction in permeability as compared with a like film formed of said acrylic matrix polymer.

33. The barrier film according to Claim 24, having a kaolin content of from 20 weight percent to 60 weight percent.

34. The barrier film according to Claim 24, having a kaolin content of from 25 weight percent to 40 weight percent.

35. The barrier film according to Claim 24, having a thickness of at least 1 micron.

36. The barrier film according to Claim 24, having a thickness of at least 2 microns.

37. The barrier film according to Claim 24, having a thickness of from 0.5 micron to 20 microns.

38. The barrier film according to Claim 24, adhered to a polymer substrate.