Release coating for tapes

Abstract

The present disclosure provides a composition. In an embodiment, the composition is a release coating composed of an acrylic dispersion. The acrylic dispersion is composed of (i) an acrylic-based polymer, (ii) a surfactant, (iii) a neutralizer, and (iv) an ethoxylated phosphate ester. The release coating can be used on a release-coated side of a substrate.

Description

RELEASE COATING FORTAPESBACKGROUND

[0001] Adhesive tapes are typically wound into a roll on their own substrate (also referred to as self-wound tapes). The substrate of self-wound tape can itself be a release coating. Alternatively, the substrate can be treated on one side with a release agent to form a release coating. The release coating is designed so that it possesses a sufficiently low adhesion force, relative to the adhesive side of the tape, to allow the tape to unwind or release from the release coating. If the adhesive force of the release coating is not sufficiently low relative to the adhesive side of the tape, the tape will have problems unwinding and releasing from the release coating.

[0002] The release coating needs to meet certain rheological criteria to ensure consistent coat weight (coatability) and unwind stability. In addition, release coating requirements further include (i) heat, humidity, aging, and water resistance as well as (ii) suitable rheology and coating weight for an acceptable unwind release force.

[0003] Conventional release coatings typically include (i) polymers prepared from monomers such as alkylacrylates and methacrylates, vinylacetate, vinylchloride, and acrylonitrile and (ii) a release agent. A class of surfactants, sulfosuccinates, are known release agent for release coatings. However, sulfosuccinates and sulfosuccinamates in particular, have been recently classified as IB reprotoxins and should be avoided because of health risk to consumers.

[0004] Thus, the art recognizes the need for a release coating for tapes that is environmentally-friendly and health-friendly and does not include a sulfosuccinate as release agent, the release coating capable of providing low release force, good water resistance, and stable re-adhesion.SUMMARY

[0005] The present disclosure provides a composition. In an embodiment, the composition is a release coating composed of an acrylic dispersion. The acrylic dispersion is composed of (i)an acrylic-based polymer, (ii) a surfactant, (iii) a neutralizer, and (iv) an ethoxylated phosphate ester.

[0006] The present disclosure provides an article. In an embodiment, the article includes a substrate. The substrate has a release-coated side and a side opposing the release-coated side. The release-coated side has a release coating. The release coating includes (i) an acrylicbased polymer, (ii) a surfactant, (iii) a neutralizer, and (iv) an ethoxylated phosphate ester.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a graph showing water contact angle measured on crepe paper containing dried release coating for comparative and inventive release coatings.

[0008] FIG. 2. is a graph showing water contact angle measured on crepe paper containing dried release coating for comparative and inventive release coatings.DEFINITIONS

[0009] Any reference to the Periodic Table of Elements is that as published by CRC Press, Inc., 1990-1991. Reference to a group of elements in this table is by the new notation for numbering groups.

[0010] For purposes of United States patent practice, the contents of any referenced patent, patent application or publication are incorporated by reference in their entirety (or its equivalent US version is so incorporated by reference) especially with respect to the disclosure of definitions (to the extent not inconsistent with any definitions specifically provided in this disclosure) and general knowledge in the art.

[0011] The numerical ranges disclosed herein include all values from, and including, the lower and upper value. For ranges containing explicit values (e.g., 1 or 2, or 3 to 5, or 6, or 7), any subrange between any two explicit values is included (e.g., the range 1-7 above includes subranges of from 1 to 2; from 2 to 6; from 5 to 7; from 3 to 7; from 5 to 6; etc.).

[0012] Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percents are based on weight and all test methods are current as of the filing date of this disclosure.

[0013] An "acrylic-based monomer," as used herein, is a monomer containing the Structure (A) below:Structure (A)wherein Ri is a H or a Ci-Cis alkyl group, or a Ci-C4alkyl group and R2 is H or CH3. Nonlimiting examples of acrylic comonomers include acrylic acid, methacrylic acid, acrylates, and methacrylates.

[0014] The terms "blend" or "polymer blend," as used herein, is a blend of two or more polymers. Such a blend may or may not be miscible (not phase separated at molecular level). Such a blend may or may not be phase separated. Such a blend may or may not contain one or more domain configurations, as determined from transmission electron spectroscopy, light scattering, x-ray scattering, and other methods known in the art.

[0015] The term "composition" refers to a mixture of materials which comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0016] The terms "comprising," "including," "having" and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term "comprising" may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term "consisting essentially of" excludes from the scope of any succeeding recitation any other component, step, or procedure, excepting those that are not essential to operability. The term "consisting of" excludes any component, step, or procedure not specifically delineatedor listed. The term "or," unless stated otherwise, refers to the listed members individually as well as in any combination. Use of the singular includes use of the plural and vice versa.

[0017] An "ethylene-based polymer" is a polymer that contains more than 50 weight percent (wt%) polymerized ethylene monomer (based on the total amount of polymerizable monomers) and, optionally, may contain at least one comonomer. Ethylene-based polymer includes ethylene homopolymer, and ethylene copolymer (meaning units derived from ethylene and one or more comonomers). The terms "ethylene-based polymer" and "polyethylene" may be used interchangeably.

[0018] An "olefin-based polymer" or "polyolefin" is a polymer that contains more than 50 weight percent polymerized olefin monomer (based on total amount of polymerizable monomers), and optionally, may contain at least one comonomer. A nonlimiting example of an olefin-based polymer is ethylene-based polymer.

[0019] A "polymer" is a compound prepared by polymerizing monomers, whether of the same or a different type, that in polymerized form provide the multiple and / or repeating "units" or "mer units" that make up a polymer. The generic term polymer thus embraces the term homopolymer, usually employed to refer to polymers prepared from only one type of monomer, and the term copolymer, usually employed to refer to polymers prepared from at least two types of monomers. It also embraces all forms of copolymer, e.g., random, block, etc. The terms "ethylene / a-olefin polymer" and "propylene / a-olefin polymer" are indicative of copolymer as described above prepared from polymerizing ethylene or propylene respectively and one or more additional, polymerizable a-olefin monomer. It is noted that although a polymer is often referred to as being "made of" one or more specified monomers, "based on" a specified monomer or monomer type, "containing" a specified monomer content, or the like, in this context the term "monomer" is understood to be referring to the polymerized remnant of the specified monomer and not to the unpolymerized species. In general, polymers herein are referred to as being based on "units" that are the polymerized form of a corresponding monomer.TEST METHODS

[0020] Adhesion peel (T-peel, re-adhesion, and adhesion onto coated backside). Specimens of a reference tape (Tesa 4316), with a 15mm width, were cut and applied onto the coated backside of the paper ( / .e., where the release coat was applied) at a rolling speed of 10 mm / s with PSTC (2.0 Kg roll). After the defined dwell time, the average force to peel the specimens from the test panel was recorded at 90° at 300 mm / min speed over 10 cm of the coated backside of the paper, by an Adhesion Release tester Lhomargy equipment according to FTM- 1 standard. The average peel strength (Newtons per 15 millimeter (N / 15 mm)) was determined from the force versus distance profile.Dwell time (dt) for T-peel tests are:• 10 min dt in CTR conditions (23°C & 50% RH)• 4 days at 40°C• 4 days at 70°C - 80% RHFailure mode is recorded behind the value of the tests:"AF" indicates adhesion failure"CF" indicates cohesion failure

[0021] Contact Angle. Contact angle is the angle where a liquid-vapor interface contacts a solid. Here water contact angles are a measure of surface hydrophobicity. Contact angles are measured from time=0 sec (the video frame where the drop is first fully in focus) until 2 seconds after time=0 sec, measured every 0.5 seconds using a circle fit.

[0022] Glass transition temperature (Tg). The calculated glass transition temperature ("Tg") of the acrylic-based polymer is calculated by using the Fox equation (T. G. Fox, Bull. Am. Physics Soc., Volume 1, Issue No. 3, page 123 (1956)), that is, for calculating the Tg of a copolymer of monomers Ml and M2, l / Tg(calc.)=w(Ml) / Tg(Ml)+w(M2) / Tg(M2), wherein Tg(calc.) is the glass transition temperature calculated for the copolymer w(Ml) is the weight fraction of monomer Ml in the copolymer w(M2) is the weight fraction of monomer M2 in the copolymerTg(Ml) is the glass transition temperature of the homopolymer of Ml Tg(M2) is the glass transition temperature of the homopolymer of M2, all temperatures being in ° K. The glass transition temperature of homopolymers may be found, for example, in "Polymer Handbook", edited by J. Brandrup and E. H. Immergut, Interscience Publishers.

[0023] Emulsion or dispersion viscosity. Emulsion or dispersion viscosity is measured using a Brookfield Viscometer Model, and a Brookfield RV-DV-ll-Pro viscometer spindle #1 or #2, at 25°C. The sample is poured into a wide mouth cup and enough volume is poured in that when the viscometer apparatus is lowered, the spindle should be completely submerged into the dispersion. The viscometer is turned on, and set to operate at a shear rate of 60 rounds per minute (rpm). Readings are monitored for 15 minutes, or until the values stabilize, at which point, a final reading is recorded.DETAILED DESCRIPTION

[0024] The present disclosure provides a composition. In an embodiment, the composition is a release coating that includes an acrylic dispersion. The acrylic dispersion includes (i) an acrylic-based polymer, (ii) a surfactant, (iii) a neutralizer, and (iv) an ethoxylated phosphate ester.A. Release coating

[0025] A "release coating," as used herein, is a coating on a substrate, the substrate having opposing sides, with the release coating on one side and an adhesive coating on the other side, the release coating possessing a low adhesion force, relative to the adhesive coated side, to allow the adhesive coated substrate to unwind, or otherwise release, from the release coating. If the adhesive force of the release coating is not sufficiently low relative to the adhesive coated substrate, the adhesive coated substrate will have problems unwinding and releasing from the release coating.

[0026] The present release coating includes the acrylic dispersion. The acrylic dispersion is a water-based acrylic dispersion (interchangeably referred to as "emulsion polymer"). The term"water-based acrylic dispersion" is a composition wherein water is the continuous phase, i.e., a composition having an aqueous medium. The acrylic dispersion (emulsion polymer) is formed by the polymerization of one or more acrylic-based monomers and optionally other unsaturated monomers. Nonlimiting examples of suitable polymerization procedures include emulsion polymerization, mini emulsion polymerization, micro-emulsion polymerization, or suspension polymerization processes where the solvent is water.

[0027] The water-based acrylic dispersion (interchangeably referred to as "acrylic dispersion") includes one or more acrylic-based monomers (and optionally one or more other unsaturated monomers), a surfactant, an initiator, a neutralizer, ethoxylated phosphate ester, and water to the exclusion of an ethylene-based polymer. As used herein, the use of the term "(meth)" followed by another term such as acrylate refers to both acrylates and methacrylates. For example, the term "(meth)acrylate" refers to either acrylate or methacrylate; the term "(meth)acrylic" refers to either acrylic or methacrylic; the term "(meth)acrylic acid refers to either acrylic acid or methacrylic acid; and the term "(meth)acrylamide" refers to either acrylamide or methacrylamide.

[0028] Nonlimiting examples of suitable acrylic-based monomers include Ci-Ci9-alkyl (meth)acrylates, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate (i.e., lauryl (meth)acrylate), tetradecyl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, (meth)acrylic acid, butyl acrylate (BA), ethylhexyl acrylate (2-EHA), ethyl acrylate (EA), methyl acrylate (MA), butyl methyacrylate (BMA), uriedomethacrylate (UMA), octyl acrylate, isooctyl acrylate, decyl acrylate, isodecyl acrylate, lauryl acrylate, cyclohexyl acrylate, methyl methacrylate (MMA), isobutyl methacrylate, octyl methacrylate, isooctyl methacrylate, decyl methacrylate, isodecyl methacrylate, lauryl methacrylate, pentadecyl methacrylate, stearyl methacrylate, n-butyl methacrylate, C12 to Ci8 alkyl methacrylates, cyclohexyl methacrylate, methacrylic acid, and combinations thereof.

[0029] One or more other unsaturated monomers may be polymerized with the acrylicbased monomer(s). Nonlimiting examples of suitable "other unsaturated monomers" include 2-hydroxyethyl acrylate (2-HEA), 2-hydroxyl ethyl methacrylate (2-HEMA), styrene (STY), acrylonitrile (AN), vinyl ester, vinyl acetate, unsaturated carboxylic acid, monomethyacryloylethyl phosphate (PEM), and combinations thereof. Nonlimiting examples of suitable unsaturated carboxylic acid include itaconic acid, fumaric acid, citraconic acid, sorbic acid, cinnamic acid, glutaconic acid and maleic acid; monoethylenically unsaturated carboxylic anhydride, such as itaconic acid anhydride, fumaric acid anhydride, citraconic acid anhydride, sorbic acid anhydride, cinnamic acid anhydride, glutaconic acid anhydride and maleic acid anhydride; monoethylenically unsaturated amides, such as N-alkylolamides, such as (meth)acrylamide, methylol (meth)acrylamide, 2-hydroxyethyl (meth)acrylamide; and hydroxyalkyl esters of monoethylenically unsaturated carboxylic acids, such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate and combinations thereof.

[0030] The acrylic dispersion includes a surfactant. Nonlimiting examples of suitable surfactant include cationic surfactants, anionic surfactants, zwitterionic surfactants, non-ionic surfactants, and combinations thereof. The surfactant can be an anionic surfactant and / or a nonionic surfactant such as, for example, alkali metal or ammonium salts of alkyl, aryl, or alkylaryl sulfates, sulfonates or phosphates; alkyl sulfonic acids; fatty acids; ethylenically unsaturated surfactant monomers; and ethoxylated alcohols or phenols. In an embodiment, the surfactant is sodium lauryl sulfate (SLS).

[0031] The acrylic dispersion includes a neutralizer. The neutralizer serves two purposes. It improves colloidal stability by ionic repulsive interactions of deprotonated (meth)acrylic acid moieties. It also provides a way to improve the solubility of the post-additive ethoxylated phosphate ester surfactants. Nonlimiting examples of suitable neutralizer include NaOH, KOH, NH4OH, Borax, NaHCO3, KHCO3, Na2CO3, K2CO3, Na2HPO4, K2HPO4, Na2B4O7, and organoamines (alkylamines, alkanolamines) such as methylamine, ethylamine, isopropylamine, n-butylamine, n-hexylamine, n-octylamine, 2-ethylhexylamine, diethylamine, di-n-butylamine, diisopropylamine, triethylamine, tri-n-butylamine, benzylamine, 2-phenyl-ethylamine, 2-amino-2-methyl-l-propanol, monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, N-methylethanolamine, N-methyldiethanolamine, N,N- dimethylethanolamine, and combinations thereof. In an embodiment, the neutralizer is ammonium hydroxide, or NH4OH.

[0032] The surfactant acts as an emulsifier and enables droplets of the acrylic-based monomer (and optional other unsaturated monomer), which is hydrophobic, to form throughout the aqueous medium. An initiator is then introduced into the emulsified mixture. The initiator reacts with the acrylic-based monomer(s) (and optional other unsaturated monomer) dispersed throughout the aqueous medium until all, or substantially all, of the acrylic-based monomer(s) (and optional other unsaturated monomer) is / are polymerized. The end result is an acrylic dispersion composed of a dispersion of acrylic-based polymer particles in the aqueous medium, the acrylic-based polymer particles composed of one or more acrylic-based monomer subunits (and optional other unsaturated monomer) to the exclusion of ethylene-based polymer. A neutralizer is added to adjust the pH of the resulting acrylic-based polymer particles to the desired pH range. The neutralizer also serves to solubilize the post-additive surfactant, i.e., the ethoxylated phosphate ester when the ethoxylated phosphate ester is in the un-neutralized phosphate acid form. The ethoxylated phosphate ester is then added as a post-additive surfactant.

[0033] In an embodiment, the acrylic-based polymer includes (i) one or more acrylic-based monomers selected from butyl acrylate, ethyl acrylate, methyl methacrylate, methacrylic acid, and combinations thereof and (ii) one or more other unsaturated polymers selected from of 2-hydroxyethyl acrylate, styrene, acrylonitrile, vinyl ester, vinyl acetate, itaconic acid, N- methylol (meth)acrylamide and combinations thereof. The acrylic-based polymer has a Tg from 0°C to 75°C, or from 5°C to 60°C, or from 10°C to 50°C and a Mw from greater than 50,000 daltons to 10,000,000 daltons.

[0034] The acrylic dispersion includes an ethoxylated phosphate ester. The ethoxylated phosphate ester is added as a post-additive surfactant (i.e., added after polymerization). Theethoxylated phosphate ester is a release agent. As a "release agent," the ethoxylated phosphate ester (i) enables the release coating to bond to the substrate so that the release coating does not delaminate from the substrate when placed in contact with the adhesive coating and (ii) prevents the release coating from migrating into the adhesive coating, thereby preventing deterioration of the adhesive coating.

[0035] The ethoxylated phosphate ester has the Structure (1) below:Structure (1)wherein m is an integer from 1 to 9, n is an integer from 6 to 22,Ri is H or a linear or branched alkyl and / or alkenyl group containing 6 to 22 carbon atoms, andStructure (1) has a degree of ethoxylation "EO" from 1 to 12.

[0036] In an embodiment, the ethoxylated phosphate ester has the Structure (1) below:Structure (1)wherein m is an integer from 1 to 4, n is an integer from 8 to 22,Ri is H or a linear or branched alkyl and / or alkenyl group containing 8 to 22 carbonatoms,Structure (1) has a degree of ethoxylation "EO" from 1 to 12, and the value of integer n is the same as the number of carbon atoms for Ri. By way of example if n is the integer 12, then Ri is a linear or branched alkyl and / or alkenyl group containing 12 carbon atoms.

[0037] In an embodiment, the acrylic dispersion of the release coating comprises, or consists of,(i) from 10 wt% to 70 wt% of the acrylic polymer,(ii) from 0.1 wt% to 6 wt% of the surfactant,(iii) from 0.1 wt% to 6 wt% of the neutralizer, and(iv) from 0.1 wt% to 20 wt%, or from 0.1 wt% to 6 wt% of the ethoxylated phosphate ester, wherein weight percent is based on the total dry weight of the acrylic dispersion.

[0038] In an embodiment, the acrylic dispersion of the release coating comprises, or consists of,(i) from 90 wt% to 98 wt% or from 95 wt% to 98 wt% of the acrylic polymer that is monomers consisting of butyl acrylate, methyl methacrylate, methacrylic acid, and uriedomethacrylate, based on total weight the acrylic polymer,(ii) from 0.1 wt% % to 1.5 wt%, or from 0.5 wt% to 1.0 wt% of the surfactant,(iii) from 0.01 wt% to 0.5 wt% or from 0.1 wt% to 0.5 wt% of the neutralizer that is ammonium hydroxide, and(iv) from 0.1 wt% to 5 wt%, or from or from 0.5 wt% to 3.0 wt% of the ethoxylated phosphate ester, wherein weight percent is based on the total dry weight of the acrylic dispersion.

[0039] In an embodiment, the acrylic dispersion includes a crosslinking monomer. A nonlimiting example of a suitable crosslinking monomer is N-methylol acrylamide.

[0040] In an embodiment, the acrylic dispersion includes inorganic particles. Suitable inorganic particles include aluminium hydroxide, aragonite, barium sulphate, calcite, calcium sulphate, dolomite, magnesium hydroxide, magnesium carbonate, magnesite, ground calcium carbonate, precipitated calcium carbonate, titanium dioxide, satin white, zinc oxide, silica, alumina trihydrate, mica, talc, clay, calcined clay, diatomaceous earth and vaterite or anycombination thereof.

[0041] In an embodiment, the adhesive acrylic dispersion optionally includes one or more additives. Nonlimiting examples of suitable additives include defoamers, rheology modifiers, solvents, coalescing agents, biocides, preservatives, and combinations thereof. Commercially available defoamers include, but are not limited to, Tego Antifoam 2291, Foamaster MO S090, Tego Antifoam KS 53, Tego Antifoam 2450, Tego Antifoam D 2315, BYK Oil, and Fluxair A-97.B. Article

[0042] The present disclosure provides an article. In an embodiment, the article includes a substrate. The substrate has a release-coated side and a side opposing the release-coated side. The release-coated side is composed of the present release coating. In particular, the release-coated side is composed of the release coating composed of (i) the acrylic-based polymer, (ii) the surfactant, (iii) the neutralizer, and (iv) the ethoxylated phosphate ester.

[0043] The article includes the substrate. The substrate can be a film, a cellulose-based material, a fabric (woven or non-woven), a tape, or a release liner, and combinations thereof.

[0044] In an embodiment, the substrate is a film. Nonlimiting examples of films suitable for the substrate include plastic films (unstretched film, or uniaxially stretched film, or biaxially stretched film) such as propylene-based polymer film, ethylene-based polymer film, ethylene / propylene copolymer films, polyester films, polyfvinyl chloride) films, metallized films, foam substrates such as polyurethane foams, and polyethylene foams; and metal foils such as aluminum foils or copper foils.

[0045] In an embodiment, the substrate is a cellulose-based material. Nonlimiting examples of cellulose-based material suitable for the substrate include paper such as craft paper, crepe paper and Japanese paper, labels, and cardboard.

[0046] In an embodiment, the substrate is a fabric. Nonlimiting examples of fabric suitable for the substrate include cotton fabrics, staple-fiber fabrics, nonwoven fabrics such as polyester nonwoven fabrics, vinyl on nonwoven fabrics, and combinations thereof.

[0047] In an embodiment, the substrate is a release liner. Nonlimiting examples of suitablematerials for the release liner include fluorocarbon polymers (e.g., polytetrafluoroethylene, polychlorotrifluoro-ethylene, polyvinyl fluoride, polyvinylidene fluoride, a tetrafluoroetylene- hexafluoropropylene copolymer, a chlorofluoroethylene-vinylidene fluoride copolymer, etc.), siliconized paper or film, and non-polar polymers (e.g., olefin-based resins such as ethylenebased polymers and propylene-based polymers.

[0048] In an embodiment, the thickness of the substrate (film, cellulose-based material, fabric, tape, or release liner) is from 10 microns to 10000 microns, or from 10 microns to 1000 microns, or from 20 microns to 500 microns, or from 50 microns to 100 microns, or from 100 microns to 200 microns, or from 200 microns to 500 microns.

[0049] The substrate has a release-coated side and a side opposing the release-coated side. The release-coated side is composed of the present release coating. The release coating is formed by applying the present water-based acrylic dispersion onto one side of the substrate, followed by drying or curing. For the application of the water-based aqueous dispersion, a coater, e.g., a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, curtain coater, slot die coater, comma coater, knife coater or the like, can be employed. In an embodiment, the surface ofthe substrate to which the water-based acrylic dispersion is applied is subjected to a surface treatment. Nonlimiting examples of suitable surface treatments include a primer coating, and a corona discharge treatment prior to application of the water-based acrylic dispersion onto the substrate surface.

[0050] Upon drying, the particles of the water-based acrylic dispersion coalesce on the release- coated side of the substrate to form a uniform release coating, or a substantially uniform release coating, on the substrate. The release coating is coextensive with, or substantially coextensive with, the substrate surface, thereby forming the release-coated side. The release coating is in direct contact with the release coated side of the substrate. The term "directly contacts" or "in direct contact with" refers to a layer configuration whereby a first layer is located immediately adjacent to a second layer and no intervening layers or no intervening structures are present between the first layer and the second layer. In an embodiment, the thickness of the releasecoating is from 0.5 micron to 500 microns, or from 10 microns to 110 microns, or from 30 microns to 90 microns, or from 0.5 micron to 10 microns, or from 10 microns to 50 microns.

[0051] In an embodiment, the article includes the substrate with the release-coated side and the present release coating directly thereon. On the opposing side of the substrate, the article further includes an adhesive-coated side with an adhesive coating on the adhesive-coated side.

[0052] In an embodiment, the article is a tape and the substrate is wound onto itself to form a roll so that the adhesive-coated substrate side is placed in direct contact with, or in physical contact with, the release- coated substrate side.

[0053] The release coating has a strong affinity for the substrate but a weak affinity for the adhesive coating. The release coating makes it possible for the tape to be unwound from the roll (i) without using excessive force (low release peel force) and (ii) without causing the adhesive coating to adhere to the release-coated substrate side. The low affinity of the release coating toward the adhesive coating should be maintained over prolonged exposure to wide variations of temperature and humidity. The release coating bonds to the release- coated side of the substrate so that the release coating does not delaminate when the tape is unwound from the roll. Components of the release coating do not migrate into the adhesive coating, and the release coating does not deteriorate the properties of the adhesive coating.

[0054] By way of example, and not limitation, some embodiments of the present disclosure will now be described in detail in the following Examples.EXAMPLES

[0055] The materials used in the inventive examples ("IE") and comparative samples ("CS") are provided in Table 1 below.

[0056] Table 1A. Synthesis of release coating

[0057] Polymer A is an aqueous dispersion with a 50% solids content and a pH of 9 and contains 135 nm particles of an acrylic-based polymer composed of 54% methyl methacrylate / 44% butyl acrylate / 1% methacrylic acid / 1% uriedomethacrylate with 0.5% (wherein percent is weight percent based on total weight of the acrylic-based polymer), and sodium lauryl sulfate surfactant. The composition of the aqueous acrylic dispersion precursor (without ethoxylated phosphate ester) (Polymer A) is provided in Table 2A below.

[0058] Table 2A. Acrylic dispersion precursor (without phosphate ester)

[0059] To the Polymer A, ethoxylated phosphate ester (or "PhosE" as post-additive surfactant) was added to the aqueous dispersion based on wt% actives / polymer solids. Acidic phosphate ester surfactant was converted to the corresponding neutralized salt (ethoxylated phosphate ester) prior to adding to the aqueous dispersion by adding a stoichiometric amount of a neutralizer (i.e., ammonium hydroxide, hard base (NaOH or KOH), organic bases (MEA, DEA, or TEA), or borax, etc.) in an aqueous solution to the acidic phosphate ester. The phosphate ester is first diluted in warm water (50°C) and subsequently neutralized with theneutralizer to a solution pH of 7-9. A viscous stage may occur during neutralization for example when the total solids is greater than about 30 wt%. The targeted % total solids of the final formulation was 40% total solids. Ammonium hydroxide was used to adjust the pH to a range from 9.5 to 10. The composition for (i) comparative samples and (ii) inventive examples of the acrylic dispersion (with ethoxylated phosphate ester) are provided in Table 3A and Table 3B below.

[0060] Table 2B. Release coating (with phosphate ester), based on total dry weight of the release coating

[0061] Table 3A. Acrylic dispersions*(50% total solids),&target 40% total solids, * PhosE / polymer solids,s(cP) (Brookfield LV#1, 60 rpm, 25°C), ® water to dilute post-additive surfactant

[0062] Table 3B. Acrylic dispersions (continued)*(50% total solids),&target 40% total solids,#PhosE / polymer solids,5(cP) (Brookfield LV#1, 60 rpm, 25°C), ® water to dilute post-additive surfactantB. Preparation of Release Coatings

[0063] Release coatings were prepared via direct coating of the emulsion with a stainless steel meyer bar set to 24.0 gsm± 0.5 pm (wet) thickness, for a dry coating weight of 3.0 gsm + 0.5 gsm onto white Gessner saturated crepe paper over a levelled lamination table. To achieve the desired coat weight, the formulations were diluted to 14% total solids. After coating, the films were introduced into an air-convection oven at 120 + 2 °C for 3 minutes and placed in a controlled-temperature room (CTR) at 23.0 + 0.5 °C and 50 ± 5 % RH for conditioning overnight.

[0064] Table 4AF: Adhesive Failure * T-Peel Adhesion* 180° peel adhesion 1 min dt

[0065] In Table 4 above, CS1 contains Aerosol 18P which is a sodium neutralized Cisnitrogenated sulfosuccinamate surfactant that is now classified as reprotoxic. IE1, IE2, and IE3 contain ethoxylated phosphate ester surfactants instead of Aerosol 18P. All the samples show initial adhesion values "Adhesion onto coated backside" that are lower than the Negative Control (the Negative Control contains no post-additive surfactant) showing the post-additive surfactant lowers the adhesion i.e lowers the release force. Additionally, after four days at 70°C and 80% relative humidity, the adhesion onto coated backside value is lower than the Negative Control sample. IE1-IE3 containing the ethoxylated phosphate ester surfactants with EO4, varying carbon chain length between Cs-Cis and ammonium hydroxide neutralization all have lower initial adhesion onto coated backside values than CS1. After four days at 70°C and 80% relative humidity the adhesion onto coated backside values for IE1-IE3 are low. IE1 shows an initial adhesion value that is lower than CS1 and a final adhesion value after aging that is comparable to CS1.

[0066] Table 5AF: Adhesive Failure* T-Peel Adhesion* 180° peel adhesion 1 min dt

[0067] Table 5 above contains a Negative Control with no ethoxylated phosphate ester. IE4, IE2, and IE5 contain an C12-C16 EO 4, ammonium hydroxide neutralized ethoxylated phosphate ester surfactant with increasing molar levels of 0.0069, 0.014, and 0.02 moles, respectively. At the lowest molar levels of ethoxylated phosphate ester surfactant in IE4, the adhesion onto the coated backside is slightly reduced compared to the Negative Control and is the second highest value of initial adhesion out of the examples and comparative shown in Table 5, indicating that the release force was reduced upon a small amount of the ethoxylated phosphate ester, but that higher amounts may be needed to further lower the release force. Additionally, IE4 has the highest adhesion onto coated backside after aging at 70°C and 80% relative humidity second to the Negative Control. Increasing the molar levels above 0.0069 moles in IE2 and IE5 shows there is decreased adhesion (easier release) when greater molar levels of the ethoxylated phosphate ester surfactant are used. When comparing IE2 to CS2 (containing a C12, EO4, ammonium sulfate surfactant), both samples have relatively low initial adhesion onto coated backside, but on aging CS2 has a relatively high adhesion value (2.7x increase from the initial adhesion), showing at the same molar level, the ethoxylated phosphate ester surfactant performs better on aging than the sulfate surfactant of similar structure.

[0068] The structural features of the post-additive surfactant impact the resistance properties of the film. To probe this, the water contact angle was measured of the dried release coating on crepe paper.

[0069] FIG. 1 shows water contact angle measured on crepe paper containing dried release coating. In FIG. 1, sample CS2 (containing a C12, EO 4, ammonium sulfate surfactant) displayed the lowest initial water contact angle in combination with the largest increase in adhesion factor on aging (see Table 5 and FIG.l). The inventive examples are superior to CS2 because they have better water resistance and a lower increase in adhesion factor on aging, showing that the inventive examples maintain low adhesion values (low release force) even when exposed to higher temperature and humidity conditions. At the same molar level, better water resistance was achieved by IE2 (C12-C16, EO 4, ammonium hydroxide ethoxylated phosphate ester surfactant)compared to the sulfate surfactant of similar structure (CS2). Furthermore, the contact angle is very close to the contact angle of CS1 (Aerosol 18P) that is known to be used as a release agent surfactant in the industry of waterborne aqueous acrylic release coatings.

[0071] In Table 6 above, the neutralizer impacts the adhesion onto coated backside values of samples containing C12-C16, EO 4 ethoxylated phosphate ester surfactant at the same molar values with different neutralizing species. IE2 and IE6-11 in Table 6 each has lower adhesion onto coated backside initially and after aging at 70°C and 80% relative humidity than the Negative Control. I Ell using Borax as a neutralizer shows relatively lower adhesion onto coated backside values initially and after aging. Furthermore, the adhesion increase factor is the lowest showing the sample can maintain the low adhesion particularly well on aging.

[0072] The neutralizer can impact the resistance properties of the film, including water resistance FIG. 2 shows water contact angle measured on crepe paper containing dried release coating. In Table 6 and FIG. 2, 1 Ell (Borax) and IE6 (sodium hydroxide) neutralized samples show the lowest initial water contact angle. The adhesion data in combination with the water contact angle shows that the combination of an ethoxylated phosphate ester surfactant(s) with specific neutralizers can give a range of resistance properties of the final film. Using ammonium hydroxide and TEA impart better water resistance than other neutralizers in formulations containing ethoxylated phosphate ester surfactants. IE9 containing TEA as the neutralizing species had the highest water contact angle. TEA may be used in combination with ethoxylated phosphate ester surfactants to impart better water resistance. IE9 also had superior water resistance to CS1, showing that ethoxylated phosphate esters can impart superior water resistance compared to Aerosol 18P. IE2 containing ammonium hydroxide neutralizer gave comparable water resistance compared to CS1.

[0073] Table 7

[0074] In Table 7 above, IE12-16 have the same molar levels of a C12 ammonium hydroxide neutralized ethoxylated phosphate ester surfactant but vary in the degree of ethoxylation of the surfactant. IE12-IE16 all have lower adhesion (easier release) onto coated backside initially and after aging at 70°C and 80% relative humidity than the Negative Control. The factor of adhesion increase on aging increases at higher EO content (I E15 and I E16), showing that lower degrees of ethoxylation may impart better aging performance at higher temperature and humidity, however I E15 and IE16 are effective at reducing the release force relative to the Negative Control making them useful as release agents.

[0075] Increasing degrees of ethoxylation of the ethoxylated phosphate esters tends to increase the hydrophilicity of the final film (FIG. 2). The water contact angle data of release coatings (FIG. 2) shows that I E 16 was the most hydrophilic out of the inventive samples with the lowest initial contact angle. Release coatings generated from I E12, 1 E 15, and I E 16 all had greater contact angles (more water resistance than CS2). When comparing the degree of ethoxylation, lower degrees of ethoxylation impart better water resistance in the films containing ethoxylated phosphate ester surfactants, but even at greater degrees of ethoxylation (IE15 and IE16) the inventive samples have better water resistance at comparable molar levels than CS2 where the post-additive surfactant is a sulfate surfactant with a shorter degree of ethoxylation (EO4). This differentiates ethoxylated phosphate ester surfactants as superior options as release agents compared to sulfates because they impart low release but also better water resistance, especially at lower degrees of ethoxylation. Furthermore, at lower degrees of ethoxylation in the case of IE2 (EO4) and IE5 (EO3), the water contact angle of the films is comparable or greater, respectively, than CS1, containing Aerosol 18P.

[0076] It is specifically intended that the present disclosure not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.

Claims

CLAIMS1. A release coating comprising: an acrylic dispersion comprising(i) an acrylic-based polymer;(II) a surfactant;(iii) a neutralizer; and(iii) an ethoxylated phosphate ester.

2. The composition of claim 1 wherein the acrylic-based polymer comprises acrylicbased monomers selected from the group consisting of butyl acrylate, methyl methacrylate, methacrylic acid, and combinations thereof.

3. The composition of claim 2 wherein the acrylic-based polymer comprises one or more other unsaturated monomers selected from the group consisting of 2-hydroxyethyl acrylate, styrene, acrylonitrile, vinyl ester, vinyl acetate, and combinations thereof.

4. The composition of any of claims 1-3 wherein the neutralizer is selected from the group consisting of NaOH, KOH, NH4OH, organoamines, Borax, NaHCOa, KHCO3, Na2COa, K2CO3, Na2HPO4, K2HPO4, Na2B4O7, and combinations thereof.

5. The composition of any of claims 1-4 wherein the ethoxylated phosphate ester has a Structure (1)Structure (1)wherein m is an integer from 1 to 9, n is an integer from 6 to 22,Ri is H or an alkyl group containing from 6 to 22 carbon atoms.

6. The composition of claim 5 wherein the ethoxylated phosphate ester has the structure (1),Structure (1)m is an integer from 1 to 4; n is an integer from 8 to 22; andRi is either H or an alkyl group with from 8 to 22 carbon atoms.

7. The release coating of any of claims 1-6 wherein the acrylic dispersion comprises(i) from 10 wt% to 70 wt% of the acrylic polymer,(ii) from 0.1 wt% to 6 wt% of the surfactant,(iii) from 0.1 wt% to 6 wt% of the neutralizer, and(iv) from 0.1 wt% to 20 wt% of the ethoxylated phosphate ester, wherein weight percent is based on the total dry weight of the acrylic dispersion.

8. The release coating of any of clams 1-7 comprising a crosslinking monomer.

9. The release coating of any of claims 1-8 comprising inorganic particles.

10. An article comprising: a substrate having a release-coated side and a side opposing the release-coated side; and the release-coated side has a release coating comprising(i) an acrylic-based polymer,(ii) a surfactant,(iii) a neutralizer, and(iv) an ethoxylated phosphate ester.

11. The article of claim 10 wherein the substrate is selected from the group consisting of a film, a cellulose-based material, a fabric, a tape, a release liner, and combinations thereof.

12. The article of any of claims 10-11 wherein the opposing side is an adhesive-coated side having an adhesive coating.

13. The article of any of claims 10-12 wherein the release-coated side is in direct contact with the adhesive-coated side.

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