Acrylic-Based Adhesive Composition with Ethylene Vinyl Acetate

Abstract

The present disclosure is directed to a water-based pressure-sensitive adhesive composition. In an embodiment, the water-based pressure-sensitive adhesive composition includes (A) an acrylic dispersion composed of particles of (i) an acrylic-based polymer with a glass transition temperature (Tg) less than -20° C., and (ii) a surfactant. The water-based pressure-sensitive adhesive composition also includes (B) an ethylene vinyl acetate (EVA) dispersion comprising (i) particles of an ethylene and vinyl acetate copolymer having from 10 wt% to less than 50 wt% vinyl acetate comonomer, and (ii) a dispersant. Further disclosed are articles with the water-based pressure-sensitive adhesive composition.

Claims

1. A water-based pressure-sensitive adhesive composition comprising: (A) an acrylic dispersion comprising particles of (i) an acrylic-based polymer with a glass transition temperature (Tg) less than 20° C., and (ii) a surfactant; (B) an ethylene vinyl acetate (EVA) dispersion comprising (i) particles of an ethylene and vinyl acetate copolymer having from 10 wt% to less than 50 wt% vinyl acetate comonomer, and (ii) a dispersant.

2. The water-based pressure-sensitive adhesive composition of claim 1 wherein the acrylic-based polymer includes one or more acrylic-based monomers selected from the group consisting of acrylic acid (AA), butyl acrylate (BA), ethylhexyl acrylate (2-EHA), ethyl acrylate (EA), methyl acrylate (MA), butyl methacrylate (BMA), 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, C.sub.12 to C.sub.18 alkyl methacrylates, cyclohexyl methacrylate, methacrylic acid, and combinations thereof.

3. The water-based pressure-sensitive adhesive of claim 2 wherein the acrylic-based polymer includes a monomer selected from the group consisting of styrene, vinyl ester, and combinations thereof.

4. The water-based pressure-sensitive adhesive composition of claim 1 wherein the acrylic-based polymer has a Tg from -80° C. to -20° C.

5. The water-based pressure-sensitive adhesive composition of claim 1 wherein the particles of the EVA copolymer have a volume average particle size from 0.1 micron to 2.0 microns.

6. The water-based pressure-sensitive adhesive composition of claim 1 wherein the EVA copolymer has a melt index from 1 g/10 min to 600 g/10 min.

7. The water-based pressure-sensitive adhesive composition of claim 1 wherein the ethylene and vinyl acetate copolymer has a density from 0.920 g/cc to 0.970 g/cc, a melting point, Tm, from 40° C. to 75° C., and a Vicat softening point from 20° C. to 65° C.

8. The water-based pressure-sensitive adhesive composition of claim 1 wherein the dispersant is selected from the group consisting of a long chain fatty acid having from 14 to 40 carbon atoms, an anionic surfactant, a cationic surfactant, a nonionic surfactant, a polyethylene with acid functionality, a polypropylene with acid functionality, and combinations thereof.

9. The water-based pressure-sensitive adhesive composition of claim 1 wherein the dispersant is a long chain fatty acid having from 14 to 40 carbon atoms.

10. The water-based pressure-sensitive adhesive composition of claim 1 comprising (A) from 40 wt% to 99.8 wt% of the acrylic dispersion; (B) from 10 wt % to 0.2 wt% of the EVA dispersion; (C) from 0 wt% to 50 wt% tackifier; wherein weight percent is based on the total dry weight of the water-based pressure-sensitive adhesive composition.

11. An article comprising: a first substrate; and a layer of a water-based pressure-sensitive adhesive composition on the first substrate, the water-based pressure-sensitive adhesive composition comprising (A) an acrylic dispersion comprising particles of (i) an acrylic-based polymer with a glass transition temperature (Tg) less than -20° C., and (ii) a surfactant; (B) an ethylene vinyl acetate (EVA) dispersion comprising (i) particles of an ethylene and vinyl acetate copolymer having from 10 wt% to less than 50 wt% vinyl acetate commoner, and (ii) a dispersant.

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

Description

DETAILED DESCRIPTION

[0040] The present disclosure relates to a water-based pressure-sensitive adhesive composition. In an embodiment, the water-based pressure-sensitive adhesive composition includes (A) an acrylic dispersion composed of (i) an acrylic-based polymer with a glass transition temperature (Tg) less than -20° C., and (ii) a surfactant. The water-based pressure-sensitive adhesive composition also includes (B) an ethylene vinyl acetate (EVA) dispersion. The EVA dispersion is composed of (i) an ethylene and vinyl acetate copolymer and (ii) a dispersant. The ethylene and vinyl acetate copolymer contains from 10 wt% to less than 50 wt% vinyl acetate comonomer and is in the form of particles.

A. Acrylic Dispersion

[0041] The water-based PSA composition includes an acrylic dispersion. The term “water-based PSA composition” is a pressure sensitive adhesive composition wherein water is the continuous phase, i.e., a composition having an aqueous medium. The acrylic dispersion includes one or more acrylic-based monomers, a surfactant, and water to the exclusion of an ethylene-based polymer. The surfactant acts as an emulsifier and enables droplets of the acrylic-based 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) dispersed throughout the aqueous medium until all, or substantially all, of the acrylic-based monomer(s) is 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 to the exclusion of ethylene-based polymer.

[0042] The acrylic-based polymer has a Tg less than -20° C., or from -80° C. to -20° C., or from -70° C. to -30° C., or from -60° C. to -40° C. and a Mw from greater than 100,000 daltons to 10,000,000 daltons. Nonlimiting examples of suitable acrylic-based monomers include acrylic acid (AA), butyl acrylate (BA), ethylhexyl acrylate (2-EHA), ethyl acrylate (EA), methyl acrylate (MA), butyl methyacrylate (BMA), 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, C.sub.12 to C.sub.18 alkyl methacrylates, cyclohexyl methacrylate, methacrylic acid, and combinations thereof. In addition to acrylic-based monomer, the acrylic-based polymer may also include monomer such as 2-hydroxyethyl acrylate (2-HEA), styrene (STY), vinyl ester, vinyl acetate, and combinations thereof.

[0043] The acrylic-based dispersion includes a surfactant. Nonlimiting examples of suitable surfactant include cationic surfactants, anionic surfactants, zwitterionic surfactants, non-ionic surfactants, and combinations thereof. Examples of anionic surfactants include, but are not limited to, sulfonates, carboxylates, and phosphates. Examples of cationic surfactants include, but are not limited to, quaternary amines. Examples of non-ionic surfactants include, but are not limited to, block copolymers containing ethylene oxide and silicone surfactants, such as ethoxylated alcohol, ethoxylated fatty acid, sorbitan derivative, lanolin derivative, ethoxylated nonyl phenol, or alkoxylated polysiloxane. Commercially-available examples of suitable surfactants include, but are not limited to, surfactants sold under the trade names TERGITOL™ and DOWFAX™ by The Dow Chemical Company, such as TERGITOL™ 15-S-9 and DOWFAX™ 2A1, and products sold under the DISPONIL trade name by BASF SE, such as DISPONIL FES 77 IS and DISPONIL FES 993.

[0044] The initiator can be either a thermal initiator or a redox system initiator. Examples of the thermal initiator include, but are not limited to, ammonium persulfate, sodium persulfate, and potassium persulfate. When the initiator is a redox system initiator, the reducing agent can be, for example, an ascorbic acid, a sulfoxylate, or an erythorbic acid, while the oxidating agent can be, for example, a peroxide or a persulfate.

[0045] In an embodiment, the acrylic dispersion includes particles of an acrylic-based polymer having the following properties: [0046] (i) two or more monomer subunits selected from any combination of 2-EHA, MA, MMA, STY, 2-HEA, AA, BA, EA, VA, and BMA; and [0047] (ii) a Tg from -60° C. to -30° C.

[0048] In an embodiment, the acrylic dispersion includes particles of an acrylic-based polymer having the following properties: [0049] (i) monomer subunits of 2-EHA, EA, MMA, and AA; and [0050] (ii) a Tg from -60° C. to -30° C.

[0051] In an embodiment, the acrylic dispersion includes particles of an acrylic-based polymer having the following properties: [0052] (i) monomer subunits of 2-EHA, MMA, STY, 2-HEA, AA, and BA; and [0053] (ii) a Tg from -60° C. to -30° C.

B. Ethylene Vinyl Acetate Dispersion

[0054] The water-based PSA composition includes an ethylene vinyl acetate (EVA) dispersion. The EVA dispersion includes particles of an ethylene and vinyl acetate copolymer, a dispersant, and water. The ethylene and vinyl acetate copolymer (or EVA copolymer) consists of (i) ethylene, (ii) vinyl acetate, and (iii) optionally one or more comonomers. The EVA copolymer contains greater than 50 wt% ethylene monomer. The EVA copolymer contains from 10 wt% to less than 50 wt% vinyl acetate monomer. Weight percent is based on the total weight of the EVA copolymer. The EVA copolymer is present to the exclusion of oxidized ethylene vinyl acetate copolymer (such as oxidized ethylene vinyl acetate copolymer manufactured by oxidation of ethylene-vinyl acetate copolymers with oxygen at elevated temperature) and to the exclusion of vinyl acetate-ethylene copolymer prepared by emulsion polymerization in water.

[0055] It is understood the particles of the EVA copolymer are distinct from the particles of the acrylic-based polymer present in the acrylic dispersion. In an embodiment, the particles of EVA copolymer have one, some, or all of the following properties: [0056] (i) a vinyl acetate content from 15 wt% to 40 wt%, or from 17 wt% to 35 wt%; and/or [0057] (ii) a volume average particle size from 0.1 micron to 2.0 microns, or from 0.2 microns to 1.5 microns, or from 0.5 microns to 1.2 microns; and/or [0058] (iii) a melt index (MI) from 1 g/10 min to 600 g/10 min, or from 3 g/10 min to 600 g/10 min, or from 30 g/10 min to 550 g/10 min, or from 40 g/10 min to 500 g/10 min; and/or [0059] (iv) a density from 0.920 g/cc to 0.970 g/cc, or from 0.927 g/cc to 0.965 g/cc; and/or [0060] (v) a melting point, Tm, from 40° C. to 75° C., or from 47° C. to 73° C.; and/or [0061] (vi) a Vicat softening point from 20° C. to 65° C., or from 27° C. to 62° C.

[0062] In an embodiment, the EVA copolymer consists of (i) ethylene, (ii) vinyl acetate, and (iii) one or more comonomers. Nonlimiting examples of suitable comonomers include acrylic acid, methacrylic acid, carbon monoxide, maleic anhydride, glycidyl methacrylate, unsubstituted alkyl esters of acrylic acid and methacrylic acid. When the optional comonomer is present, the total amount of comonomer is from greater than 0 wt% to less than 15% and the total amount of ethylene and vinyl acetate is from less than 100 wt% to greater than 85% based on total weight of the EVA copolymer. In a further embodiment, the comonomer is present in an amount from greater than 0 wt% to less than 8% and the total amount of ethylene and vinyl acetate is from greater than 92% to less than 100 wt%, based on total weight of the EVA copolymer.

[0063] Commercially available examples of suitable ethylene-vinyl acetate copolymer include, but are not limited to, products sold under the trade name ELVAX™ by The Dow Chemical Company such as ELVAX™ 220W, ELVAX™ 240W, ELVAX™ 210W, ELVAX™150W, ELVAX™ 40W, ELVAX™ 410, ELVAX™ 40W, ELVAX™ 420, ELVAX™ 440, ELVAX™ 440, ELVAX™ 450, ELVAX™ 550, ELVAX™ 265, ELVAX™ 4310, and ELVAX™ 4320.

[0064] In an embodiment, the water-based pressure-sensitive adhesive composition includes from 0.1 wt% to 25 wt%, or from 0.1 wt% to 10 wt%, or from 0.2 wt% to 6 wt% of the ethylene-vinyl acetate polymer, based on total dry weight of the water-based pressure-sensitive adhesive composition.

[0065] The EVA dispersion includes the dispersant. The dispersant provides colloidal stability for the EVA copolymer while in the EVA dispersion. The dispersant is selected from a long chain fatty acid having from 14 to 40 carbon atoms, an anionic surfactant, a cationic surfactant, a nonionic surfactant, a polyethylene with acid functionality, a polypropylene with acid functionality, and combinations thereof. In an embodiment, the dispersant is a long chain fatty acid having from 14 to 40 carbon atoms, or from 16 to 36 carbon atoms, or from 18 to 24 carbon atoms and optionally neutralized with a base such as potassium hydroxide, sodium hydroxide, and/or dimethylethanolamine. Nonlimiting examples of long chain fatty acids suitable for the dispersant include lauric acid (C.sub.12), palmitic acid (C.sub.16), oleic acid (C.sub.18) stearic acid (C.sub.18), arachidic acid (C.sub.20), euricic acid (C.sub.22), behenic acid (C.sub.22), and combinations thereof.

[0066] In an embodiment, the dispersant is an anionic surfactant. Nonlimiting examples of anionic surfactants suitable for the dispersant include sodium lauryl ether sulfonate, sodium dodecylbenzene sulfonate, sodium C.sub.14-C.sub.16 alpha olefin sulfonate, and DOWFAX™ 2A1 available from The Dow Chemical Company.

[0067] In an embodiment, the dispersant is a cationic surfactant. Nonlimiting examples of cationic surfactants suitable for the dispersant include stearamidopropyl dimethylamine.

[0068] In an embodiment, the dispersant is a nonionic surfactant. Nonlimiting examples of nonionic surfactants suitable for the dispersant include poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) and poly(ethylene glycol) alkyl ethers.

[0069] In an embodiment, the dispersant is polyethylene or polypropylene with acid functionality. Nonlimiting examples of polyethylene or polypropylene with acid functionality include ethylene copolymers with acrylic acid, methacrylic acid, maleic acid, or maleic anhydride.

D. Tackifier

[0070] In an embodiment, the water-based pressure sensitive adhesive composition includes a tackifier. Suitable tackifiers include, but are not limited to, rosin resins including rosin acid and/or rosin ester obtained by esterifying rosin acid with alcohols or an epoxy compound and/or its mixture, non-hydrogenated aliphatic C.sub.5 resins, hydrogenated aliphatic C.sub.5 resins, aromatic modified C.sub.5 resins, terpene resins, hydrogenated C.sub.9 resins, (meth)acrylic resins, and combinations thereof. (Meth)acrylic resins suitable as tackifiers are described in references US 4,912,169, US 2002/055587, and US 9,605,188. The water-based pressure-sensitive adhesive composition contains from greater than 0 wt% to 50 wt%, or from 5 wt% to 40 wt%, or from 7 wt% to 30 wt%, or from 8% to 15 wt% of the tackifier based on total dry weight of the water-based pressure sensitive adhesive composition.

E. Additives

[0071] The water-based pressure sensitive adhesive composition may further include one or more optional additives. When the additive is present, nonlimiting examples of suitable additives include thickener, defoamer, wetting agent, mechanical stabilizer, pigment, filler, freeze-thaw agent, neutralizing agent, plasticizer, adhesion promoter, and combinations thereof.

[0072] In an embodiment, the water-based pressure sensitive adhesive composition includes from greater than 0 wt% to 5 wt% thickener, based on the total dry weight of the water-based pressure sensitive adhesive composition. Suitable thickeners include, but are not limited to, ACRYSOL™, UCAR™ and CELLOSIZE™ which are commercially available from The Dow Chemical Company, Midland, Michigan.

[0073] In an embodiment, the water-based pressure-sensitive adhesive composition includes from greater than 0 wt% to 2 wt% of a neutralizing agent, based on the total dry weight of the water-based pressure-sensitive adhesive composition. The neutralizing agent is used to control pH and provide stability to the formulated pressure sensitive adhesive composition. Suitable neutralizing agents include, but are not limited to, aqueous ammonia, aqueous amines, and other aqueous inorganic salts.

C. PSA Composition

[0074] The water-based PSA composition contains [0075] (A) from 40 wt% to 99.9 wt%, or from 93 wt% to 99.8 wt%, or from 95 wt% to 99.7 wt% of the acrylic-based dispersion; [0076] (B) from 10 wt% to 0.1 wt%, or from 7 wt% to 0.2 wt%, or from 5 wt% to 0.3 wt% of the EVA dispersion; and [0077] (C) 0 wt%, or from greater than 0 wt% to 50 wt%, or from 5 wt% to 40 wt%, or from 7 wt% to 30 wt%, or from 8% to 15 wt% tackifier, wherein weight percent is based on the total dry weight of the water-based pressure-sensitive adhesive composition.

D. Article

[0078] The present disclosure provides an article. The article includes a first substrate and a layer of a water-based PSA composition on the first substrate (hereafter PSA layer). The water-based PSA composition is any water-based PSA composition as previously disclosed herein and includes the acrylic dispersion (A) composed of (i) the acrylic-based polymer with a glass transition temperature (Tg) less than -20° C., and (ii) the surfactant; the ethylene vinyl acetate (EVA) dispersion (B) composed of (i) particles of an ethylene and vinyl acetate copolymer and (ii) a dispersant and (C) optional tackifier. The ethylene and vinyl acetate copolymer contains from 10 wt% to less than 50 wt% vinyl acetate comonomer.

[0079] In an embodiment, the article is a pressure sensitive adhesive article. A “pressure sensitive adhesive article,” as used herein, is an article in which a pressure sensitive adhesive (PSA) is adhered to a first substrate, the PSA having an “available surface,” the available surface being an exposed surface, available to make contact with a second substrate. The available surface of the PSA may or may not be in contact with a release material. A “release material,” as used herein, is a material that forms a weak bond with the PSA, such that the PSA may be readily removed by hand to expose the available surface.

[0080] The article includes a first substrate. The first substrate is a film, a cellulose-based material, a fabric, a tape, or a release liner, and combinations thereof.

[0081] In an embodiment, the first substrate is a film. Nonlimiting examples of films suitable for the first 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, poly(vinyl chloride) films, metallized films, foam substrates such as polyurethane foams, and polyethylene foams; and metal foils such as aluminum foils or copper foils.

[0082] In an embodiment, the first 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.

[0083] In an embodiment, the first substrate is a fabric. Nonlimiting examples of fabric suitable for the substrate included cotton fabrics, staple-fiber fabrics, nonwoven fabrics such as polyester nonwoven fabrics, vinyl on nonwoven fabrics, and combinations thereof.

[0084] In an embodiment, the first substrate is a release liner. Nonlimiting examples of suitable materials 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 ethylene-based polymers and propylene-based polymers.

[0085] In an embodiment, the thickness of the first 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.

[0086] The PSA layer is formed by applying, on one, or both, first substrate surface(s), the water-based PSA composition, followed by drying or curing. The water-based PSA composition can be any water-based PSA composition as previously disclosed herein. For the application of the PSA composition 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(s) of the substrate to which the pressure-sensitive adhesive layer is applied is/are 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 PSA layer onto the substrate surface(s).

[0087] In an embodiment, the thickness of the PSA layer on the substrate surface is from 1 micron to 500 microns, or from 10 microns to 110 microns, or from 30 microns to 90 microns, or from 1 micron to 10 microns, or from 10 microns to 50 microns.

[0088] In an embodiment, the article is a multi-layer PSA article. A “multi-layer PSA article,” as used herein, includes a substrate and two or more PSA layers such that a first PSA layer is in contact with the substrate and a second PSA layer is in contact with the first PSA layer. The multi-layer PSA article may include additional PSA layers wherein each additional PSA layer is in contact with a preceding PSA layer, the PSA layers arranged in a stacked manner. For example, the multi-layer PSA article can include a third PSA layer, the third PSA layer in contact with, and stacked upon, the second PSA layer. The multi-layer PSA article can include a fourth PSA layer, the fourth PSA layer in contact with, and stacked upon, the third PSA layer. The multi-layer PSA article can include a fifth PSA layer, the fifth PSA layer in contact with, and stacked upon, the fourth PSA layer. At least one of the PSA layers of the multi-layer PSA article is composed of any water-based PSA composition as previously disclosed herein.

[0089] By way of example, and not limitation, some embodiments of the present disclosure will now be described in detail in the following Examples.

EXAMPLES

[0090] Materials used in the examples are provided in Table 1A and 1B below.

TABLE-US-00001 Materials used in the comparative samples (CS) and inventive examples (IE) Material/Description Properties Source COHESA 3050 Acrylic dispersion An oil-in-water dispersion of an ethylene acrylic acid copolymer (“EAA”) having active solids of 38.5 - 41.4%, and a viscosity of less than or equal to about 100 cps (Brookfield viscosity at 25° C.) Honeywell International, Inc. TERGITOL™ 15-S-9 Nonionic surfactant The Dow Chemical Company AEROSOL OT-75 Anionic surfactant Cytec Solvay Group DISPONIL FES 77 Anionic surfactant BASF SE SURFYNOL 440 Nonionic dynamic wetting agent Evonik ACRYSOL™ RM-2020 Rheology modifier/thickener The Dow Chemical Company Sodium carbonate, ammonium persfulate, tert-butyl hydroperoxide, sodium formaldehyde bisulfite, n-dodecyl mercaptan Various chemicals Sinoreagent Company 2-ethylhexyl acrylate (“2-EHA”), ethyl acrylate (“EA”), methyl methacrylate (“MMA”), acrylic acid (“AA”), butyl acrylate (“BA”) Acrylic dispersion monomers The Dow Chemical Company Oleic acid C.sub.18H.sub.34O.sub.2, 282.5 g/mol d= 0.89 g/cc 90% purity reagent grade Sigma-Aldrich Snowtack SE782G E Rosin ester tackifier dispersion, 58% solids Lawter Snowtack SE784G E Rosin ester tackifier dispersion, 57% solids Lawter Dermulsene RE 1513 Rosin ester tackifier dispersion, 56% solids DRT Empicol ESB 70 Sodium Laureth sulfate solution in water, 70% solids Huntsman

TABLE-US-00002 EVA resins available from The Dow Chemical Company Density (g/cm.sup.3) DSC Melt Point, (Tm) (°C) Vicat Softening Point (Vsp) (°C) MI % VA* ELVAX™150W 0.957 63 36 43 32 ELVAX™ 210W 0.951 60 39 400 28 ELVAX™ 220W 0.951 70 -- 150 28 ELVAX™ 240W 0.951 74 40 43 28 ELVAX™ 410 0.934 73 53 500 18 ELVAX™ 40W 0.965 47 27 52 40 ELVAX™ 420 0.937 73 53 150 18 ELVAX™ 440 0.927 84 53 30 18 ELVAX™ 450 0.941 86 61 8 18 ELVAX™ 265 0.951 73 49 3 28 ELVAX™ 550 0.935 85 62 8 15 ELVAX™ 4310† 0.945 66 -- 500 25 ELVAX™ 4320† 0.947 72 -- 150 25 *Weight percent vinyl acetate comonomer based on total weight EVA resin .sup.†Contains 1% methacrylic acid

A. Melt Index (MI)-Melt Viscosity (Mv) Relationship

[0091] Melt Index at 190° C. may be estimated from Melt Viscosity at 140° C. according to the following calculation taken from Shenoy, A.V.; Saini, D.R.; Nadkarni, V.M. Polymer 1983, 24, 722-728. MI at a given temperature, e.g. 140° C., may be estimated from Melt Viscosity at the same temperature as follows:

[00003]$MI=\frac{49\text{,}800\times \rho \times L}{MeltViscosity}$

[0092] where MI is given in g/10 min, ρ is the polymer density in g/cm.sup.3, L is the weight used in the MI measurement in kg (typically 2.16 kg), and the melt viscosity is given in poise. Next, a rearrangement of the form of the Williams-Landel-Ferry equation provided by Shenoy et al. in the above reference may be used to estimate the MI at one temperature, MI(T.sub.2) e.g. 190° C., from the MI at another temperature, MI(T.sub.1) e.g. 140° C.: [0093] where T.sub.s is the standard reference temperature which is the polymer glass transition temperature plus 50 K, T.sub.2 is the temperature in K at which MI is to be calculated, and T.sub.1 is the temperature in K at which the MI is known. If the polymer glass transition temperature is not known, it may be estimated using the Fox equation from the glass transition temperature of the homopolymers of the component monomers: [0094] where T.sub.g is the estimated T.sub.g of the desired copolymer, w.sub.l is the weight fraction of the i-th component monomer in the desired copolymer, and T.sub.g,l is the glass transition temperature of the homopolymer of the i-th component monomer.

[0095] As an example, the MI at 190° C. for the EAA Honeywell A-C 5120 polymer may be estimated from its melt viscosity at 140° C. (6 poise), density (0.93 g/cm.sup.3), and glass transition temperature calculated for a copolymer of 85% ethylene and 15% acrylic acid.

TABLE-US-00003 MI- Mv relationship for various dispersion components Type Name E VA AA Melt Viscosity 140° C. MI 140° C. ρ T.sub.g (K, calculated) MI 190° C. (calculated) EAA Honeywell A-C 5120 85% 15% 6 16673 0.93 208 62309 Oxidized EVA Honeywell A-C 645P* 94% 6% 3.75 26964 0.94 201 92657 Oxidized PE Honeywell A-C 655 100% 2.1 47637 0.93 193 156040 Oxidized PE Honeywell A-C 656 100% 1.85 53493 0.92 193 175222 EVA Honeywell A-C 405 91.5% 8.5% 6 16494 0.92 211 63329 EAA Honeywell A-C 540 95% 5% 5.75 17398 0.93 198 59286 EAA Honeywell A-C 580 90% 10% 6.5 15473 0.935 203 55084 EAA Honeywell A-C 5180 80% 20% 6.25 16092 0.935 214 63491 *Monomer composition estimated, wt% based on total weight of material E-ethylene, VA-vinyl acetate, AA-acrylic acid

1. Preparation of Acrylic Dispersion

A. Acrylic Dispersion 1

[0096] Acrylic dispersion 1 is prepared according to the following procedure. A four liter, five-neck reactor equipped with a condenser, a mechanical stirrer, a temperature-controlled thermocouple and inlets for initiators and monomers, is fed with 540 g of deionized (“DI”) water and heated to 87° C. under a gentle nitrogen flow. In a separate container, a monomer emulsion is prepared by mixing 400 g of DI water, 11.9 g of DISPONIL FES 77, 5 g of TERGITOL™ 15-S-9, 4 g of sodium carbonate, and 2,024 g of a monomer mixture composed of 71.5 wt% of 2-ethylhexyl acrylate (“2-EHA”), 18.5 wt% of ethyl acrylate (“EA”), 9 wt% of methyl methacrylate (“MMA”), and 1 wt% of acrylic acid (“AA”). Next, a solution of a mixture of 1.3 g of sodium carbonate and 8.3 g of ammonium persulfate (“APS” as initiator) in 32 g DI water is added into the reactor. Immediately after addition of the solution of sodium carbonate and APS, the monomer emulsion is fed into the reactor. The feeding proceeds for 80 minutes. Upon completion of the monomer emulsion addition, the reaction mixture is cooled to 60° C. before gradual addition of a solution of tert-butyl hydroperoxide (70%) (“t-BHP”) (4.7 g in 23 g DI water ) and 2.8 g of sodium formaldehyde bisulfite in 28 g DI water, via two separate feeds over 25 minutes. Upon completion of the feeds, the reaction is cooled to room temperature. The obtained acrylic dispersion 1 is then filtered through 325 mesh filter cloth to prepare the composition for subsequent evaluation work. The obtained acrylic dispersion 1 includes an acrylic-based polymer composed of 71.5 wt % 2-EHA/18.5 wt% EA/9 wt% MMA/1 wt% AA, and has a glass transition temperature of -41° C. Weight percent is based on the total dry weight of the acrylic-based polymer.

B. Acrylic Dispersion 2

[0097] Acrylic Dispersion 2 is INVISU™ 4100 available from The Dow Chemical Company.

C. Acrylic Dispersion 3

[0098] Acrylic Dispersion 3 is INVISU™ 3000 available from The Dow Chemical Company.

D. Acrylic Dispersion 4

[0099] A flask set up for semi-continuous emulsion polymerization containing 270 g of water at 90° C. was charged first with sodium peroxodisulfate (1.26 g) in 13 g deionized water and second with 21.2 g of a seed consisting of an aqueous dispersion of an acrylic polymer with mean particle diameter 60 nm at 12% solids content. After two minutes, addition of a feed stream containing sodium peroxodisulfate (3.79 g) in 59.8 g deionized water and a monomer emulsion was begun and continued at a constant rate over 120 minutes at 90° C. The monomer emulsion consisted of 1250 g of monomers in proportions by weight according to Table 2, 180 g of a 33% concentration solution of a sulfuric ester sodium salt of lauryl alcohol ethoxylated by 30 moles of ethylene oxide in water, 5.6 g of a 44% strength solution of DOWFAX™ 2A1 in water, 6.7 g of a 75% concentration solution of dioctylsulfosuccinate sodium salt in ethanol/water, and 295 g of deionized water. After half of the weight of the monomer emulsion was added to the reactor, 72 g of a seed consisting of an aqueous dispersion of an acrylic polymer with mean particle diameter 60 nm at 26% solids content was charged to the reactor within one minute. After the monomer emulsion and the feed stream were fully added to the reactor, an additional 35 g of deionized water was added while the reactor temperature was maintained at 90° C. Next, ammonia (17.9 g of 4.4% concentration in water) was added to the reactor. Finally, a solution of 8% tert-butyl hydroperoxide in water (23 g) and a solution of 10% sodium formaldehyde sulfoxylate in water (19.5 g) were added to the reactor at 90° C. at a constant rate over 60 minutes. After the completion of these feed streams, the reactor contents were cooled to room temperature.

E. Acrylic Dispersion 5

[0100] Using a flask equipped with a mechanical stirrer, an initial aqueous charge composed of 0.51 grams tetrasodium pyrophosphate, 640 grams of deionized water, 1.80 grams anhydrous sodium sulfate, and 1.36 grams ascorbic acid is warmed to 87° C. Next, 28.4 grams of 19% concentration sodium persulfate in water is poured into the flask. Over a period of 2.0 hours, an emulsion made up of 14.7 grams of 50% strength aqueous sodium hydroxide solution, 39.4 grams of a 30% concentration solution of a sulfuric ester sodium salt of lauryl alcohol ethoxylated by 12 moles of ethylene oxide in water, 21.2 grams of 25.0% concentration sodium vinyl sulfonate solution in water, 28.8 grams of a 22% strength solution of sodium dodecylbenzene sulfonate in water, 6.6 grams of itaconic acid, 236 grams of water, 321.2 grams of methyl methacrylate, 55.2 grams of styrene, 1,592.4 grams of 2-ethylhexyl acrylate, 679.3 grams of ethyl acrylate, and 14.4 grams of acrylic acid is gradually fed into the flask. At the outset, the rate of addition is 5.0 grams per minute for the first 5.0 minutes. It is then raised steadily to 25.0 grams per minute over the span of 35 minutes. After 75 minutes of total feed time, the rate is raised to 35.0 grams per minute. From the outset of the emulsion feed, 94 grams of a sodium peroxodisulfate solution at 11% strength in water is added at a constant rate over 2.3 hours, and the reactor temperature is kept at 85 to87° C.

[0101] After the completion of the feeds and at roughly 70° C., a solution of 2.76 grams sodium bisulphite, 1.8 grams acetone and 44.4 grams water, and, at the same time, 47.6 grams of a 5.5% concentration solution of tert-butyl hydroperoxide is dispensed to the flask over a period of 45 minutes. A copolymer dispersion of pressure-sensitive adhesive is produced with 70% solids by weight.

F. Acrylic Dispersion 6

[0102] Using a flask equipped with a mechanical stirrer, a charge composed of 1.34 g tetrasodium pyrophosphate, 269 g of deionized water, and 0.68 g ascorbic acid is warmed to 86° C. Next, 28 g of 6.6% concentration sodium persulfate in water is poured into the flask. Over a span of four hours, an emulsion made up of 24.5 g of 10% strength aqueous sodium hydroxide solution, 30 g of a 33% concentration solution of a sulfuric ester sodium salt of lauryl alcohol ethoxylated by 30 moles of ethylene oxide in water, 10.6 g of 25.0% concentration sodium vinylsulfonate solution in water, 5 g of a 44% strength solution of DOWFAX™ 2A1 in water, 2.2 g of lauryl alcohol ethoxylated with 7 mol of ethylene oxide, 172 g of water, 27.6 g of styrene, 1,079.2 g of 2-ethylhexyl acrylate, 55.2 g of vinyl acetate, 162 g of methyl methacrylate, and 7.2 g of acrylic acid is gradually dispensed into the flask. At the outset, the rate of addition is 1.42 g/minute for the first six minutes. The rate of addition is then raised steadily to 7.1 g/minute over the span of forty minutes. From the outset of the emulsion feed, 148 g of a sodium peroxodisulfate solution at 5% strength in water is added at a constant rate over five hours, and the reaction medium is maintained from 85 to87° C.

[0103] After the completion of the feeds and at roughly 70° C., a solution of 1.38 g sodium bisulphite, 0.9 g acetone and 22.2 g water, and, at the same time, 23.8 g of a 5.5% concentration solution of tert-butyl hydroperoxide is dispensed to the flask during the span of sixty minutes.

G. Acrylic Dispersion 7

[0104] Sodium carbonate (0.01% BOM, 0.55 g) was added as buffer to a 96° C. kettle charge of a water (518 g) swept with nitrogen, equipped with overhead stirring, thermometer, and reflux condenser. This was followed by ammonium persulfate (0.217% BOM, 5.9 g) as initiator and a preform seed charge (100 nm starting particle size, 1.251% BOM, 70.79 g) to set the initial particle size. A monomer emulsion feed and cofeed were started. The monomer emulsion consisted of sodium carbonate (0.02% BOM, 1.4 g), itaconic acid (0.2%, 5.1 g), acrylic acid (0.8% BOM, 20.4 g), disodium ethoxylated alcohol half ester of sulfosuccinic acid (0.17%, 14.3 g), sodium dodecylbenzenesulfonate (0.21% BOM, 24.2 g), butyl acrylate (71.1% BOM, 1818 g), methyl methacrylate (6.0% BOM, 152.8 g), styrene (1.6% BOM, 40.8 g) and water (16.8% of total monomer emulsion, 4 1lg) and was fed for 75 minutes. The co-feed of ammonium persulfate (0.173% BOM, 4.6 g) was fed for 75 minutes. The temperature of the reaction was controlled between 88-90° C. Partway through the monomer emulsion feed an intercept of sodium dodecylbenzenesulfonate (0.235% BOM, 26.5 g) was added to the kettle. Once the addition of the monomer emulsion concluded, it was held at temperature. After fifteen minutes the kettle was cooled to 75° C. and dilute iron sulfate (0.001%BOM, 0.03 g) and tetrasodium ethylenediaminetetraacetate (0.001%BOM, 0.03 g) was added to the kettle. Subsequently a monomer emulsion feed and cofeeds were started. The monomer emulsion consisted of tetrasodium 1,1-diphosphonatoethanol (0.002%, 0.1 g), acetic acid (0.03%BOM, 0.6 g), sodium dodecylbenzenesulfonate (0.05% BOM, 5.3 g), butyl acrylate (5%BOM, 127.8 g), butyl methacrylate (15% BOM, 353.3 g), 3-methylmercaptopropionate (0.38%BOM, 9.8 g) and water (105.7 g) for 20 minutes. One cofeed consisted of t-butlyhydroperoxide (0.4% BOM, 15.1 g) and was fed for 50 minutes. The other cofeed consisted of sodium hydroxymethanesulfonate (0.24%BOM, 8.1 g) and was fed for 50 minutes. During the monomer emulsion feed the temperature was controlled at 74-76° C. Once the monomer emulsion finished, the batch was allowed to cool to 65° C. The dispersion was then neutralized with ammonium hydroxide until a pH of 7 was obtained. After neutralization the batch was cooled to below 35° C.

[0105] Table 2 below summarizes the properties for acrylic dispersions 1-7 where component amounts are shown as weight percent based on dry weight of the acrylic dispersion.

TABLE-US-00004 Acrylic dispersions composition and properties Component Acrylic Dispersion 1 Acrylic Dispersion 2 Acrylic Dispersion 3 Acrylic Dispersion 4 Acrylic Dispersion 5 Acrylic Dispersion 6 Acrylic Dispersion 7 2-EHA 71.5 80 59.5 80.9 - MA - 8 - - - MMA 9 8 12.0 12.1 6.0 Styrene - 2 2.1 2.1 1.6 2-hydroxyethyl acrylate - 1 - - - AA 1 1 0.55 0.55 0.8 BA - 0 - - 76.1 EA 18.5 0 25.4 - Itaconic acid - - 0.2 - 0.2 Sodium vinyl sulfonate - - 0.25 0.25 - VA - - - 4.1 - n-butyl methacrylate - - - - 15 Property - - pH 7.5 7.75 4.75 6.1 4.5 4.2 7.0 Solids (%) 66.4 62 68 61 70 66 64 Viscosity (cP) - 1000 - - - - - Tg -41° C. -45° C. -53° C. -40° C. -33° C. -46 -26°C Wt% based on dry weight of acrylic dispersion

2. Preparation of EVA Dispersion

[0106] An aqueous EVA dispersion was prepared utilizing a Bersdorf ZE25 48 L/D 25 mm twin screw extruder (Kraus-Maffei Corporation, Florence KY, USA) rotating at 450 rpm according to the following procedure. The EVA copolymer resin (EVA feed 1 in Table 3 below) was supplied to the feed throat of the extruder via a Schenck Mechatron loss-in-weight feeder and K-tron loss in weight feeders to control blend composition. The EVA resin was melt blended, and then emulsified in the presence of initial aqueous stream (IA) and oleic acid (dispersant), neutralized with potassium hydroxide (KOH), both injected using ISCO dual syringe pumps (from Teledyne Isco, Inc., Lincoln NE, USA). The dispersion phase was then conveyed forward to the dilution and cooling zone of the extruder where additional dilution water was added by ISCO dual syringe pumps to form the aqueous dispersion having solid level content less than 70 weight percent. The barrel temperature of the extruder was set to 140-150° C. After the EVA dispersion exited the extruder, it was further cooled and filtered via a 200 .Math.m mesh size bag filter.

[0107] Specific feed rates and results are shown in Table 3 below.

TABLE-US-00005 Preparation parameters for EVA dispersions Sample EVA Feed 1, g/min Surfactant, g/min 1A, mL/min Neutralizing Base, mL/min Dilution Water, mL/min Vmean Particle size (.Math.m) EVA1 (ELVAX™150W) 75.6 ELVAX™ 150W 2.7 Oleic Acid 3.7 1.2, 50% KOH 75 0.300 d 0.957 Tm 63 Vsp 36 MI 43 VA 32 EVA2 (ELVAX™ 210W) 72.7 ELVAX™210W 3.4 Oleic Acid 2.4 1.5, Dimethyl ethanolamine 177 0.420 d 0.951 Tm 60 Vsp 39 MI 400 VA 28 EVA3 (ELVAX™ 220W) 136.1 ELVAX™220W 5.5 Oleic Acid 4.2 2.9, 30% KOH 135 0.210 d 0.951 Tm 70 Vsp MI 150 VA 28 EVA4 (ELVAX™ 240W) 75.7 ELVAX™240W 2.7 Oleic Acid 3.2 1.6, 30% KOH 110 0.360 d 0.951 Tm 74 Vsp 40 MI 43 VA 28 EVAS (ELVAX™ 410W) 72.6 ELVAX™410W 3.0 Oleic Acid 2.4 1.5, Dimethyl ethanolamine 113 0.330 d 0.934 Tm 73 Vsp 53 MI 500 VA 18 EVA 6 (ELVAX™ 40W) 75.7 Elvax 40w 2.7 Oleic Acid 2.5 1.6, 30% potassium hydroxide 111 0.340 EVA 7 (ELVAX™ 220W) 70.0 Elvax 200W 5.0 Empicol ESB 70 6.5 None added 100 1.253 EVA 8 (ELVAX™ 440) 151.4 Elvax 440 6.1 Oleic Acid 2.9 4.1, 30% potassium hydroxide 220 0.526 EVA 9 (ELVAX™ 550) 151.4 Elvax 550 6.1 Oleic Acid 4.6 4.1, 30% potassium hydroxide 220 1.155 EVA 10 (ELVAX™ 265) 75.7 Elvax 265 2.7 Oleic Acid 2.4 1.6, 30% potassium hydroxide 110 1.552 EVA 11 (ELVAX™ 450) 75.7 Elvax 450 2.4 Oleic Acid 2.8 1.6, 30% potassium hydroxide 110 0.849 EVA 12 (ELVAX™ 4310) 72.6 Elvax 4310 3.0 Oleic Acid 6.3 1.8, 30% potassium hydroxide 90 0.564 EVA 13 (ELVAX™ 4320) 72.6 Elvax 4320 3.0 Oleic Acid 3.8 1.6, 30% potassium hydroxide 90 0.525 EVA14 (ELVAX™ 420) 75.7 Elvax 420 2.7 Oleic Acid 6.0 1.6, 30% potassium hydroxide 110 0.363

3. Preparation of Pressure Sensitive Adhesive Composition

[0108] Water-based pressure sensitive adhesive composition was formulated as follows. All samples were formulated with a wetting agent, 0.3% (wet/wet) SURFYNOL440 wetting agent obtained from Evonik (“440”), based on total dispersion, to improve wet-out for lab drawdowns unless otherwise specified. The viscosity was then adjusted to approximately 600 mPa.s (600 cps) (Brookfield, RVDV, 30 rpm, 63#) using a thickener, ACRYSOL™ DR-5500, available from The Dow Chemical Company, Midland, Michigan (“DR-5500”), and final pH was adjusted to 7.0 to 7.5 using ammonium hydroxide.

[0109] The acrylic dispersion was blended with EVA dispersion according to the dosage level shown in the respective table (wet or dry weight based on total weight of acrylic dispersion) under proper agitation.

4. Preparation of PSA Article

Lab Drawdowns

[0110] Polypropylene (“PP”) film (60 microns in thickness) was pre-treated by corona treatment before lamination. Samples of the water-based PSA composition were coated onto a release paper and dried at 80° C. for 5 minutes. The PP film was laminated with the water-based pressure-sensitive adhesive coated release liner (“adhesive laminate”).

[0111] Performance testing was conducted after the adhesive laminate was conditioned in a controlled environment (22.2 to 23.3° C. (72 to74° F.), 50% relative humidity) for at least 1 day (24 hours).

[0112] High density polyethylene (HDPE) panels purchased from Cheminstruments (510 Commercial Dr., West Chester Township, OH 45014) are cleaned and conditioned prior to being used for adhesive testing. Panels are wiped with lint-free, non-abrasive cloth soaked in isopropanol to remove any adhesive residue from prior testing. Care is taken not to scratch the surface. Once panel surface appears clean, an additional wipe is performed using isopropanol. The HDPE panel is conditioned for a minimum of 4 hours but no more than 24 hours at 22.2 to23.3° C. (72 to74° F.), 50% relative humidity.

5. PSA Application Tests

[0113] Performance testing was conducted after the water-based PSA composition in the adhesive laminate was completely dried and conditioned in a controlled environment (22.2 to 23.3° C., 50 % relative humidity) testing laboratory for at least overnight, and in some instances after as many as 120 hours under 12 kg of weight.

[0114] The peel adhesion, loop tack, and shear data for adhesive laminates with the dried PSA compositions composed of (i) acrylic dispersion 1 and (ii) either COHESA 3050 or EVA dispersion are provided in Table 4 below.

TABLE-US-00006 Peel adhesion, loop tack, and shear data for adhesive laminates with dried PSA compositions Parts of Acrylic Dispersion 1 by wet weight Additive (Parts by wet weight) Additive (weight % based on total dry weight) Additive Melt Index (10 g/min) 90° Peel SS, N/in, 20 min 90° Peel HDPE, N/in, 24 hr Loop Tack SS, N/in Loop Tack HDPE, N/in Shear, SS, h CS1 100 Cohesa 3050 (1) 0.6 >500 MI 6.3 3.4 9.1 5.1 85.6 IE1 100 EVA2 (10) 5.7 400 6.6 3.8 9.3 5.7 69.9 IE2 100 EVA3 (10) 5.7 150 6.6 4.2 8.1 5.1 51.5 IE3 100 EVA4 (10) 5.7 43 5.3 4.7 6.0 4.2 58.2 CS - comparative sample, IE - inventive example

[0115] The 90° HDPE peel adhesion (24 hr) observed for PSA articles (laminates) prepared from formulations of acrylic dispersion 1 with ethylene copolymer dispersions unexpectedly increases with decreasing MI. CS1 with >500MI exhibits 90° HDPE peel adhesion (24 hr) of 3.4 N/in compared to IE3 with 43 MI and 90° HDPE peel adhesion of 4.7 N/in.

[0116] Based on the prior art laminates utilizing high MI (>500 MI) and low molecular weight copolymer additives which are anionic and highly polar, it would be expected that nonionic and nonpolar EVA additives with low MI (less than 500 MI) to have poor compatibility with the polyolefin substrate and the acrylic copolymer, and hence such formulations to have poor adhesion. Applicant unexpectedly discovered that the reverse is true. The formulation with low molecular weight (Cohesa 3050 ethylene acrylic acid dispersion (CS1)) has lower adhesion to HDPE (lower 90° HDPE peel adhesion, 3.4 N/in) than each inventive example IE1 (3.8 N/in), IE2 (4.2 N/in) and IE3 (4.7 N/in).

[0117] The peel adhesion and loop tack for adhesive laminates with dried PSA compositions composed of (i) acrylic dispersion 2 and (ii) EVA dispersion are provided in Table 5 below.

TABLE-US-00007 Peel adhesion and loop tack data for adhesive laminates with dried PSA compositions Acrylic dispersion 2 parts by wet weight Additive (Parts by Dry Weight) Additive (weight % based on total dry weight) %VA in EVA resin MI of EVA resin 90° Peel (HDPE), 20 min, N/2.54 cm 90° Peel (HDPE), 24 h, N/2.54 cm Loop Tack (HDPE), N CS2 100 0 0 n/a 3.9 4.6 5.5 IE4 100 EVA3 (0.4) 0.6 28 150 (12.5 kDa) 4.2 5.7 5.1 IE5 100 EVA3 (2) 3.1 4.4 5.6 5.6 IE6 100 EVA3 (4) 5.9 4.8 6.1 5.3 IE7 100 EVA5 (0.4) 0.6 18 500 (9.8 kDa) 3.8 4.8 5.2 IE8 100 EVAS (2) 3.1 4.4 5.2 5.1 IE9 100 EVAS (4) 5.9 4.8 5.4 5.3 IE10 100 EVA2 (0.4) 0.6 28 400 (11.3 kDa) 4.8 5.3 4.9 IE11 100 EVA2 (2) 3.1 4.6 6.1 5.3 IE12 100 EVA2 (4) 5.9 4.5 5.4 5.3 IE13 100 EVA4 (0.4) 0.6 28 43 (15.1 kDa) 3.9 5.2 4.8 IE14 100 EVA4 (2) 3.1 4.4 5.4 5.0 IE15 100 EVA4 (4) 5.9 4.7 5.5 5.2 IE16 100 EVA1 (0.4) 0.6 32 43 (16.6 kDa) 4.1 5.4 4.8 IE17 100 EVA1 (2) 3.1 4.4 5.1 4.6 IE18 100 EVA1 (4) 5.9 4.5 5.3 4.4 CS - comparative sample IE - inventive example

[0118] The 90° HDPE peel adhesion (24 hrs) observed for PSA articles (laminates) formulations of acrylic dispersion 2 with ethylene copolymer dispersions is higher than that of laminates prepared from acrylic dispersion 2 alone. Based on the prior art utilizing high MI and low molecular weight ethylene copolymer additives which are anionic and highly polar, it would be expected that low melt index additives such as EVAs which are nonionic and have low polarity would have poor compatibility with the acrylic polymer such that these formulations would have poor adhesion. Instead, these formulations improve adhesion to HDPE, regardless of the level of VA in the EVA. The relative increase in 90° HDPE peel adhesion (24 hrs) when EVA dispersion concentration is increased from 0 (CS2) to 0.4 parts to 2.0 parts to 4.0 parts (IE4-IE18) is not linear. In some cases such as IE10 to IE 12 and IE16 to IE18 a significant improvement in 90° HDPE peel adhesion is exhibited by 0.4 phe solids addition but the increase levels off after that In other cases such as IE4 to IE6, IE7 to 9, and IE 13 to 15, the 90° HDPE peel adhesion gradually increases as more EVA dispersion is added.

6. Preparation of Pressure Sensitive Adhesive Compositions Containing Tackifiers

[0119] Water-based pressure sensitive adhesive compositions containing tackifiers were formulated as follows: All samples were formulated with wetting agents, 0.3% (wet/wet) Aerosol OT-75 obtained from Solvay and 0.1% (wet/wet) Surfynol 440 based on total dispersion, to improve wet-out for lab drawdowns unless otherwise specified. For samples containing tackifier, the tackifier is added at a level of 10% (dry weight tackifier/dry weight total formulation). Tackifiers used were Snowtack SE782G and Snowtack SE784G from Lawter and Dermulsene RE 1513 from DRT. EVA3 was added to selected samples at a level of 1% (wet/wet) based on total dispersion. The final pH was adjusted to 7.0 to 8.0 using ammonium hydroxide.

[0120] Samples of the water-based PSA compositions containing tackifiers were coated onto a release paper and dried at 105° C. for 2 minutes. Wood-free vellum paper (70 g/m.sup.2) was laminated with the pressure sensitive adhesive coated release liner (“adhesive laminate”). The dry coat weight of adhesive was 18 g/m.sup.2.

[0121] Performance testing was conducted after the adhesive laminate was conditioned in a controlled environment (22.2 to23.3° C. (72 to74° F.), 50% relative humidity) for at least 4 hours.

[0122] Table 6: Peel adhesion and loop tack data for adhesive laminates with dried PSA compositions containing tackifiers.

TABLE-US-00008 Acrylic dispersion 3 parts by wet weight Tackifier (parts by wet weight) EVA3 parts by wet weight Tackifier (wt % by total dry weight) EVA3 (wt % by total dry weight) 90° Peel HDPE, N/in, 20 min 90° Peel HDPE, N/in, 24 h Loop Tack Glass, N/in Loop Tack HDPE, N/in Shear, glass, h CS3 100 0 0 0 0 3.8 4.2 11.2 6.7 >250 CS4 100 SE782G (13) 0 10 0 4.2 4.5 10.6 7.8 >250 CS5 100 SE784G (13.22) 0 10 0 4.1 4.6 12.8 7.9 >250 CS6 100 RE 1513 (13.41) 0 10 0 4.0 4.4 12.9 8.1 114 IE19 100 SE782G (13) 1 10 0.5 4.9 5.1 12.3 9.0 >250 IE20 100 SE784G (13.22) 1 10 0.5 4.7 5.5 11.1 8.5 >250 IE21 100 RE 1513 (13.41) 1 10 0.5 4.7 5.3 11.8 8.5 93

[0123] Tackifiers act to increase the adhesion of PSAs because they have low molecular weight and high glass transition temperature. In the prior art low molecular weight, anionic, and highly polar ethylene copolymers such as ethylene acrylic acid copolymer or oxidized polyethylene showed effectiveness in increasing the adhesion of tackified PSA formulations. Therefore it is surprising that nonionic and less polar EVA which is not oxidized and has lower melt index would increase the adhesion of tackified PSA formulations.

7. Formulation of Acrylic Dispersions With EVA3

[0124] The acrylic dispersion was blended with the EVA dispersion according to the dosage level shown in the respective table (wet weight based on total weight of acrylic dispersion) under proper agitation to achieve mixing.

TABLE-US-00009 Acrylic dispersion (parts by weight) EVA3 parts by weight IE22 Acrylic dispersion 4 (100) 1 IE23 Acrylic dispersion 5 (100) 1 IE24 Acrylic dispersion 6 (100) 1 IE25 Acrylic dispersion 7 (100) 1

8. Formulation of Acrylic Dispersions With EVA6

[0125] In a separate experiment, EVA6 was formulated with Acrylic Dispersion 2 and PSA application tests were performed according to the methods described above. The peel adhesion and loop tack for adhesive laminates with dried PSA compositions composed of (i) acrylic dispersion 2 and (ii) EVA dispersion 6 are provided in Table 8 below.

TABLE-US-00010 Peel adhesion and loop tack data for adhesive laminates with dried PSA compositions Acrylic dispersion 2 parts by wet weight Additive (Parts by Dry Weight) Additive (weight % based on total dry weight) %VA in EVA resin MI of EVA resin 90° Peel (HDPE), 20 min, N/2.54 cm 90° Peel (HDPE), 24 h, N/2.54 cm CS2 100 0 0 n/a n/a 5.1 6.7 IE26 100 EVA6 (0.4) 0.6 40 52 5.6 8.0 IE27 100 EVA6 (2) 3.1 40 52 5.5 6.7 CS - comparative sample IE - inventive example

[0126] The 90° HDPE peel adhesion (20 min and 24 hrs) observed for PSA articles (laminates) formulations of acrylic dispersion 2 with ethylene copolymer dispersion EVA6 is higher than that of laminates prepared from acrylic dispersion 2 alone. Based on the prior art utilizing high MI and low molecular weight ethylene copolymer additives which are anionic and highly polar, it would be expected that low melt index additives such as EVAs which are nonionic and have low polarity would have poor compatibility with the acrylic polymer such that these formulations would have poor adhesion. Instead, these formulations improve adhesion to HDPE.

9. Formulation of Acrylic Dispersions With EVA7, EVA8, EVA9, EVA10, and EVA11

[0127] In a separate experiment, EVA7-11 were formulated with Acrylic Dispersion 2 and PSA application tests were performed according to the methods described above. The peel adhesion and loop tack for adhesive laminates with dried PSA compositions composed of (i) acrylic dispersion 2 and (ii) EVA dispersions 7-11 are provided in Table 9 below.

TABLE-US-00011 Peel adhesion and loop tack data for adhesive laminates with dried PSA compositions Acrylic dispersion 2 parts by wet weight Additive (Parts by Dry Weight) Additive (weight % based on total dry weight) %VA in EVA resin MI of EVA resin 90° Peel (HDPE), 20 min, N/2.54 cm 90° Peel (HDPE), 24 h, N/2.54 cm CS2 100 0 0 n/a n/a 3.6 3.8 IE28 100 EVA7 (0.4) 0.6 28 150 4.2 5.1 IE29 100 EVA8 (0.4) 0.6 18 30 4.0 4.4 IE30 100 EVA8 (2) 3.1 18 30 3.7 4.9 IE31 100 EVA9 (0.4) 0.6 15 8 3.4 4.2 IE32 100 EVA9 (2) 3.1 15 8 4.0 4.7 IE33 100 EVA10 (0.4) 0.6 28 3 4.0 4.6 IE34 100 EVA10 (2) 3.1 28 3 3.9 4.9 IE35 100 EVA11 (0.4) 0.6 18 8 4.0 4.9 IE36 100 EVA11 (2) 3.1 18 8 3.9 4.9 CS - comparative sample IE - inventive example

[0128] The 90° HDPE peel adhesion (20 min and 24 hrs) observed for PSA articles (laminates) formulations of acrylic dispersion 2 with ethylene copolymer dispersion EVA7-11 is higher than that of laminates prepared from acrylic dispersion 2 alone. Based on the prior art utilizing high MI and low molecular weight ethylene copolymer additives which are anionic and highly polar, it would be expected that low melt index additives such as EVAs which are nonionic and have low polarity would have poor compatibility with the acrylic polymer such that these formulations would have poor adhesion. Instead, these formulations improve adhesion to HDPE. In the case of IE31, the 20 min HDPE adhesion is not higher than that of CS2, but over time the adhesion of the formulation with EVA9 improves such that the HDPE adhesion is higher than that of CS2 at 24 h.

Formulation of Acrylic Dispersions With EVA12 and EVA13

[0129] In a separate experiment, EVA12-13 were formulated with Acrylic Dispersion 2 and PSA application tests were performed according to the methods described above. The peel adhesion and loop tack for adhesive laminates with dried PSA compositions composed of (i) acrylic dispersion 2 and (ii) EVA dispersions 12-13 are provided in Table 10 below.

TABLE-US-00012 Peel adhesion and loop tack data for adhesive laminates with dried PSA compositions Acrylic dispersion 2 parts by wet weight Additive (Parts by Dry Weight) Additive (weight % based on total dry weight) %VA in EVA resin MI of EVA resin 90° Peel (HDPE), 20 min, N/2.54 cm 90° Peel (HDPE), 24 h, N/2.54 cm CS2 100 0 0 n/a n/a 3.8 4.7 IE37 100 EVA12 (0.4) 0.6 25 500 4.1 5.5 IE38 100 EVA12 (2) 3.1 25 500 4.7 5.6 IE39 100 EVA13 (0.4) 0.6 25 150 5.3 6.4 IE40 100 EVA13 (2) 3.1 25 150 5.0 6.2

[0130] The 90° HDPE peel adhesion (20 min and 24 hrs) observed for PSA articles (laminates) formulations of acrylic dispersion 2 with ethylene copolymer dispersion EVA12-13 is higher than that of laminates prepared from acrylic dispersion 2 alone. Based on the prior art utilizing high MI and low molecular weight ethylene copolymer additives which are anionic and highly polar, it would be expected that low melt index additives such as EVA12 and EVA13 which have low polarity would have poor compatibility with the acrylic polymer such that these formulations would have poor adhesion. Instead, these formulations improve adhesion to HDPE.

11. Formulation of Acrylic Dispersions With EVA14

[0131] In a separate experiment, EVA14 was formulated with Acrylic Dispersion 2 and PSA application tests were performed according to the methods described above. The peel adhesion and loop tack for adhesive laminates with dried PSA compositions composed of (i) acrylic dispersion 2 and (ii) EVA dispersion 14 are provided in Table 11 below.

TABLE-US-00013 Peel adhesion and loop tack data for adhesive laminates with dried PSA compositions Acrylic dispersion 2 parts by wet weight Additive (Parts by Dry Weight) Additive (weight % based on total dry weight) %VA in EVA resin MI of EVA resin 90° Peel (HDPE), 20 min, N/2.54 cm 90° Peel (HDPE), 24 h, N/2.54 cm CS2 100 0 0 n/a n/a 3.4 4.2 IE41 100 EVA14 (0.4) 0.6 18 150 3.9 4.5 IE42 100 EVA14 (2) 3.1 18 150 5.0 5.8 IE40 100 EVA14 (2) 3.1 25 150 5.0 6.2

[0132] The 90° HDPE peel adhesion (20 min and 24 hrs) observed for PSA articles (laminates) formulations of acrylic dispersion 2 with ethylene copolymer dispersion EVA14 is higher than that of laminates prepared from acrylic dispersion 2 alone. Based on the prior art utilizing high MI and low molecular weight ethylene copolymer additives which are anionic and highly polar, it would be expected that low melt index additives such as EVAs which are nonionic and have low polarity would have poor compatibility with the acrylic polymer such that these formulations would have poor adhesion. Instead, these formulations improve adhesion to HDPE.

[0133] 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.