WO2018078490A1

WO2018078490A1 - Acrylic adhesive articles

Info

Publication number: WO2018078490A1
Application number: PCT/IB2017/056476
Authority: WO
Inventors: Susana SHIMIZU; Joao R. Talamoni; Carlos T. MATSUDA; Jayshree Seth
Original assignee: 3M Innovative Properties Company
Priority date: 2016-10-26
Filing date: 2017-10-18
Publication date: 2018-05-03

Abstract

An adhesive article comprising an acrylic adhesive assembly having a backing layer having a first major surface and a second major surface opposite the first major surface, and an acrylic adhesive layer disposed on at least a portion of the first major surface of the backing layer, wherein the acrylic adhesive is the reaction product of (1) an acrylic acid ester of monohydric alcohol having 5 to 10 carbon atoms; and (2) a non-polar acrylic monomer having a solubility parameter of less than 9.2 as measured by the Fedors method using a homopolymer of the non-polar acrylic monomer, wherein the reaction product has side chain crystallinity, wherein the acrylic adhesive comprises less than 0.5 percent of silicone by weight, and wherein the backing layer comprises less than 0.5 percent of silicone by weight.

Description

ACRYLIC ADHESIVE ARTICLES

TECHNICAL FIELD

[0001] Acrylic adhesive articles that are silicone free.

BACKGROUND

[0002] Pressure-sensitive adhesives ("PSAs") are generally known to possess properties that include: (1) aggressive and permanent tack, (2) adherence with no more than finger pressure, (3) sufficient ability to hold onto an adherend, and (4) sufficient cohesive strength to be removed cleanly from the adherend. Polymers that have been found to function well as PSAs, including acrylic polymers, are designed and formulated to exhibit the requisite viscoelastic properties resulting in a desired balance of characteristics such as tack, peel adhesion, and cohesion (shear holding strength). SUMMARY

[0003] In certain embodiments, the adhesive articles of this disclosure include a backing layer having a layer of an acrylic adhesive disposed on at least a portion of a first major surface of the backing layer. The acrylic adhesive is the reaction product of (i) an acrylic acid ester of monohydric alcohol having 5 to 10 carbon atoms, and (ii) a non-polar acrylic monomer having a solubility of less than 9.2 as measured with the Fedors method using a homopolymer of the non-polar acrylic monomer. The acrylic adhesive exhibits side chain crystallinity. The acrylic adhesive comprises less than 0.5 percent of silicone by weight, and the backing layer comprises less than 0.5 percent of silicone by weight. [0004] In some embodiments, the adhesive article of the present disclosure is linerless.

[0005] In some embodiments, the layer of acrylic adhesive of the adhesive articles of the present disclosure provides the desired balance of peel adhesion, tack, and relatively high shear holding strength. [0006] The following terms used in this application are defined as follows:

[0007] "Acrylate" or "Acrylic" is inclusive of both acrylate and (meth)acrylate or acrylic and (meth)acrylic. [0008] "Non-polar acrylic monomer" means an acrylic acid ester of an alcohol according to the formula R-OH, wherein R is such that R-H is non-polar.

[0009] "Renewable resource" refers to a natural resource that can be replenished within a 100 year time frame. The resource may be replenished naturally or via agricultural techniques. The renewable resource is typically a plant (i.e. any of various photosynthetic organisms that includes all land plants, inclusive of trees), organisms of Protista such as seaweed and algae, animals, and fish. They may be naturally occurring, hybrids, or genetically engineered organisms. Natural resources such as crude oil, coal, and peat which take longer than 100 years to form are not considered to be renewable resources. [0010] "Solubility Parameter" refers the solubility of the homopolymer derived from a select monomer using the Fedors method.

BRIEF DESCRIPTION OF THE DRAWINGS [0011] FIG. 1 is a cross-sectional schematic representation of an adhesive article of the present disclosure;

[0012] FIG. 2 is a cross-sectional schematic representation of a roll of an adhesive article of the present disclosure; and

[0013] FIG. 3 is a cross-sectional schematic representation of a roll of an adhesive article of the present disclosure.

DETAILED DESCRIPTION

[0014] Adhesive articles of the present disclosure include an acrylic adhesive disposed on at least a portion of a major surface of a backing layer. In the present disclosure, the acrylic adhesive has less than 0.5 percent of silicone by weight, and the backing layer has less than 0.5 percent of silicone by weight. In some embodiments, the acrylic adhesive has less than 0.1 percent of silicone by weight, and the backing layer has less than 0.1 percent of silicone by weight. In some embodiments, the acrylic adhesive is silicone-free, and the backing layer is silicone-free. A potential advantage of silicone-free adhesive articles (e.g., silicone-free adhesive labels) is that they may be more suitable for use in recycled paper, compared to adhesive articles that include higher levels of silicone.

[0015] In some embodiments, the adhesive article has no liner (i.e., the adhesive article is "linerless"). Advantageously, linerless adhesive label articles are provided that can be wound into roll form, and then unwound without requiring a liner to keep the adhesive from sticking too strongly to a surface of the backing layer (which could interfere with unwinding, for example, by leaving residual adhesive on the surface of the backing layer, which in turn could interfere with attempts to print indicia on the surface of the backing layer). Some advantages of linerless adhesive articles can include cost reduction, and enhanced ability to recycle materials, compared to adhesive articles that include a liner.

[0016] FIG. 1 shows a cross-sectional schematic representation of an exemplary embodiment of an adhesive article 100 of the present disclosure. Adhesive article 100 includes backing layer 110 and adhesive layer 130 disposed on a first major surface 112 of backing layer 110. In the present disclosure, adhesive layer 130 is selected to be an acrylic adhesive as described in greater detail below. In FIG. 1, an optional primer layer 120 is shown between backing layer 110 and adhesive layer 130. Also shown in FIG. 1 is an optional release layer 140, disposed on second major surface 114 of backing layer 110.

[0017] In some embodiments, the adhesive article of the present disclosure can be wound upon itself in a roll form, and subsequently unwound. FIG. 2 shows a cross-sectional schematic representation of an exemplary embodiment of an adhesive article 200 of the present disclosure, rolled onto a core 202. Adhesive article 200 includes backing layer 210 having adhesive layer 130 disposed on a first major surface of backing layer 210, and an optional release layer 240 disposed on a second major surface of backing layer 210. Optional release layer 240 can be included, for example, to enable clean unwinding of a roll of the adhesive article. Not shown in FIG. 2 is an optional primer layer, which could be included between backing layer 210 and adhesive layer 230.

[0018] In some embodiments, the adhesive article of the present disclosure may include an ink layer, for example, to form a printed label. FIG. 3 shows a cross-sectional schematic representation of an exemplary embodiment of an adhesive article 300 of the present disclosure, rolled onto a core 302. Adhesive article 300 includes backing layer 310 having adhesive layer 330 disposed on a first major surface of backing layer 310, optional release layer 340 disposed on a second major surface of backing layer 310, and an ink layer 350 disposed on the optional release layer. Not shown in FIG. 3 is an optional primer layer, which could be included between backing layer 310 and adhesive layer 330.

[0019] Acrylic adhesives of this disclosure are derived from the reaction product of (i) an acrylic acid ester of monohydric alcohol having 5 to 10 carbon atoms; and (ii) a non-polar acrylic monomer having a solubility of less than 9.2. The reaction product also exhibits side chain crystallinity in the acrylic adhesives resulting in a reduced segmental mobility of these side chains. The acrylic adhesive may be created in the form of a hot melt adhesive or in the form of a pressure -sensitive adhesive. Suitable acrylic adhesives include, for example, some of those acrylic adhesives described in U.S. Patent Application Serial No. 62/152227, filed on April 24, 2015, the description of which is incorporated herein by reference. For the present disclosure, the acrylic adhesive should have less than 0.5 percent by weight silicone content, less than 0.1 percent by weight silicone content, or the acrylic adhesive is even silicone- free.

[0020] For purposes of this disclosure, a pressure-sensitive adhesive or PSA can be identified by a means known as the Dahlquist criterion. This criterion defines a PSA as an adhesive having a 1 second creep compliance of greater than lxlO^"6 cm²/dyne as described in Handbook of PSA Technology, Donatas Satas (Ed.), 2^nd Edition, p. 172, Van Nostrand Reinhold, New York, N.Y., 1989. Alternatively, since modulus is, to a first approximation, the inverse of creep compliance, PSA's may be defined as adhesives having a Young's modulus of less than lxlO⁶ dynes/cm². Another well-known means of identifying a PSA is that it is aggressively and permanently tacky at room temperature and firmly adheres to a variety of dissimilar surfaces upon mere contact without the need of more than finger or hand pressure, and which may be removed from smooth surfaces without leaving a residue as described in Glossary of Terms Used in the Pressure Sensitive Tape Industry provided by the Pressure Sensitive Tape Council, 1996. Another suitable definition of a suitable PSA is that it preferably has a room temperature storage modulus within the area defined by the following points as plotted on a graph of modulus versus frequency at 25 degrees centigrade : a range of moduli from approximately 2xl0⁵ to 4xl0⁵ dynes/cm² at a frequency of approximately 0.1 radians/sec (0.017 Hz), and a range of moduli from approximately 2xl0⁶ to 8xl0⁶ dynes/cm² at a frequency of approximately 100 radians/sec (17 Hz) (for example see Fig. 8-16 on p. 173 of Handbook of PSA Technology (Donatas Satas, Ed.), 2^nd Edition, Van Nostrand Rheinhold, N.Y., 1989). Any of these methods of identifying a PSA may be used to identify suitable PSA's produced in accordance with this disclosure.

[0021] Conventional acrylic ester adhesives are typically an elastomeric polymer comprised primarily of a low T_g non-polar acrylate monomer, as well as a small amount of polar acrylic monomer such as acrylic acid. Two widely used low T_g acrylates in the acrylic adhesives 2-ethylhexyl acrylate (EHA) and isooctyl acrylate (IOA), each providing an alkyl chain of eight carbon atoms (Cs). The embodiments of this disclosure copolymerize a higher T_g non-polar acrylate monomer that possesses a solubility of less than 9.2 with the noted low T_g non-polar acrylate monomer. The resulting non-polar copolymer demonstrates a unique combination of physical characteristics such as low adhesion, high tack and sufficient cohesion to permit removal of the adhesive from an adherend. The T_g of the acrylic adhesive are generally in the range of -35 to -50 °C. Certain embodiments produced according to this disclosure exhibit a T_g of about -40 to about -45 °C.

[0022] An acrylic acid ester of monohydric alcohol having 5 to 10 carbon atoms is one of the monomers in the acrylic adhesive. The number of carbon atoms are selected to achieve a balance between sufficient T_g values and modulus. A lower number of carbon atoms may adversely impact Tg value and a higher number of carbon atoms may impact the desired tack. The homopolymer of the selected monomer has a T_g less than 0° C. Non-limiting examples of the acrylic acid ester of monohydric alcohol include 2- ethylhexyl acrylate, iso-octyl acrylate, n-octyl acrylate, nonyl acrylate, hexyl acrylate, heptyl acrylate, 2- heptyl acrylate, ethylbutyl acrylate, 3-methylbutyl acrylate, plant-based 2-octyl acrylate and fusel oil acrylate and combinations thereof. In some embodiments, the acrylic acid ester monomers are included in the polymerizable composition at about 40 percent by weight to about 90 percent by weight. In other embodiments, the acrylic acid ester monomers are comprise about 50 percent by weight to about 80 percent by weight of the polymerizable composition.

[0023] The acrylic adhesives of this disclosure employ a non-polar acrylic monomer having a homopolymer with a solubility parameter of less than 9.2 as measured by the Fedors method. The T_g value of the homopolymer is greater than 19° C. The non-polar nature of this monomer limits the adhesion build up over extended application time. It also provides the smooth peel characteristics to the adhesive. Suitable non-polar acrylic monomers are acrylic acid esters of monohydric alcohols having from about 12 to about 26 carbon atoms. Non-limiting examples include octadecyl acrylate, octadecyl methacrylate, cyclodecyl acrylate, cyclohexyl acrylate, hexadecyl acrylate, isobornyl acrylate, lauryl acrylate, lauryl methacrylate and combinations thereof. The non-polar acrylic monomer comprises about 10 percent by weight to about 60 percent of the polymerizable composition. In other embodiments, the non-polar acrylate monomers comprise about 20 percent by weight to about 50 percent by weight of the polymerizable composition.

[0024] The resulting copolymer from the reaction components of an acrylic acid ester of monohydric alcohol and a non-polar acrylic monomer possesses side chain crystallinity. The side chain crystallinity reduces segmental mobility of these side chains limiting adhesion build up over time. As a result of the crystallinity, reaction product exhibits a fusion enthalpy of at least 2.5 J/g, at least 5.5 J/g, or at least 6.0 J/g.

[0025] In some embodiments, this disclosure provides an acrylic adhesive derived from plant based or renewable resources. In particular, the acrylic adhesive may be derived, in part, from plant materials. In some embodiments, the present disclosure further provides an adhesive article, wherein the substrate or backing of the adhesive assembly may also be derived from renewable resources.

[0026] In some embodiments, the acrylic adhesives may also contain one or more conventional additives. Preferred additives include tackifiers, plasticizers, dyes, antioxidants, and UV stabilizers. Such additives can be used if they do not affect the superior properties of the acrylic adhesives. Those of ordinary skill in the art are capable of selecting an appropriate amount of the optional components to achieve desired end properties. [0027] The monomers can be polymerized by conventional techniques including, but not limited to, solvent polymerization, emulsion polymerization, and bulk polymerization. The monomer mixture may comprise a polymerization initiator, of a type and in an amount effective to polymerize the comonomers.

[0028] An optional crosslinking agent may be used in forming the acrylic adhesive. The optional crosslinking agent may be used to achieve a specific balance of adhesive properties for a selected application. A crosslinking agent is generally included in the composition for subsequent crosslinking upon application of the polymer in its desired end state. Upon activation, the crosslinking agent interacts with the functional moieties from the acrylate to improve cohesive strength. The crosslinking agent generally comprises compounds containing hydroxyl, carboxylic acid, isocyanate, azilidine or epoxy functional groups. Non-limiting example of crosslinking agents include benzophenone, triazine and acetophenone derived photocrosslinking compounds; multifunctional acrylates and methacrylate s; silanes, organo-titanium compounds, or combinations thereof. Those of ordinary skill in the art are capable of selecting a specific crosslinking agent compatible with the chosen monomers and capable of withstanding the intended adhesive manufacturing environment. The crosslinking agent is included in the acrylic adhesive in an amount of about 0.1 to about 2.0 percent by weight.

[0029] The acrylic adhesive may be self-tacky or, in alternative embodiments, may be tackified. Useful tackifiers for acrylic adhesives are rosin esters such as that available under the trade name FORAL 85 from Eastman, Inc., aromatic resins such as that available under the trade name PICCOTEX LC from Eastman, Inc., aliphatic resins such as that available under the trade name PICCOTAC 95 from Eastman, Inc., and terpene resins such as that available under the trade names PICCOLYTE A-l 15 and ZONAREZ B-100 from Arizona Chemical Co. Plant based tackifiers may be well suited in certain applications, such as for example, FORAL 85. Those of ordinary skill in the art with knowledge of this disclosure are capable of selecting an appropriate tackifier in an amount necessary to achieve desired end results for a selected application.

[0030] Many of the acrylate monomers used herein may be derived from plant based resources. In some embodiments, the plant based acrylic acid ester of monohydric alcohol is 2-octyl acrylate or fusel oil acrylate. The acrylic adhesive in certain embodiments comprises a plant based content of at least 25, 30, 35, 40, 45, or 50 percent by weight using ASTM D6866-10, method B. In other embodiments, the acrylic adhesives comprise a plant based content of at least 55, 60, 65, 70, 75, or 80 percent by weight. In yet other embodiments, the acrylic adhesives comprise a plant based content of at least 85, 90, 95, 96, 97, 98 or 99 percent by weight. Those of ordinary skill in the art will additionally recognize that many of the components in an adhesive assembly, such as tackifiers and backing materials, may be derived from plant based resources. In certain embodiments, an adhesive assembly may comprise 25 weight percent or more plant based content.

[0031] The acrylic adhesive produced in accordance with this disclosure may be employed to form adhesive articles. Acrylic PSA articles may be prepared by coating the acrylic PSA composition on a suitable support, such as a flexible backing. Non-limiting examples of materials that can be included in the flexible backing include polyolefins, such as polyethylene, polypropylene, polystyrene, polyester, polyvinyl chloride, polyurethane, polyvinyl alcohol, poly(ethylene terephthalate), poly(butylene terephthalate), poly(caprolactam), poly(vinylidene fluoride), polylactides, cellulose acetate, ethyl cellulose, paper and combinations thereof. Other non-limiting examples of commercially available backing materials include kraft paper, spun-bond polyolefins, porous films obtained from polyolefins, and multi-layered constructions. In some embodiments, monoaxially, biaxially or non-oriented polyolefins or polyvinyl chloride substrates may be used.

[0032] In some embodiments, the backing may derived from plant based or renewable resources. For example, polylactic acids, poly-L-lactic acid, and a random copolymer of L-lactic acid and D-lactic acid, and derivatives thereof may be suitable as a backing. Other non-limiting plant based materials that can serve as backing layer material include polyhydroxyalkanoates, poly-3-hydroxybutyrate, and certain polyolefins derived from renewable feedstocks.

[0033] Backing layers may also be prepared of fabric such as woven fabric formed of threads of synthetic or natural materials such as cotton, nylon, rayon, glass, ceramic materials, and the like or nonwoven fabric such as air laid webs of natural or synthetic fibers or blends of these. The backing layer may also be formed of metal, metalized polymer films, or ceramic sheet materials may take the form of any article conventionally known to be utilized with adhesives such as labels, tapes, signs, covers, marking indicia, and the like. Examples of standard dry coating weights for adhesive articles of the present disclosure are in the range of 7 to 18 g/sqm. Higher coating weights may result in greater adhesion.

[0034] The above-described acrylic PSA compositions are coated on a substrate (e.g., a backing layer) using conventional coating techniques modified as appropriate to the particular substrate. For example, these adhesive compositions can be applied to a variety of solid substrates by methods such as gravure roll coating, roller coating, flow coating, dip coating, spin coating, spray coating knife coating, and die coating. These various methods of coating allow the compositions to be placed on the substrate at variable thicknesses thus allowing a wider range of use of the compositions. Coating thicknesses may vary from a few microns to a few hundred microns. Those of ordinary skill in the art are capable of selecting an appropriate coating technique to match the backing and desired end use application.

[0035] Various forms of radiation may be employed to cure the adhesive using crosslinking agents once acrylic adhesive is applied onto a backing. For example, actinic radiation is well suited to initiate crosslinking. For purposes of this disclosure actinic radiation means electromagnetic radiation capable of inducing a chemical change in a material . Non-limiting examples of actinic radiation include wavelength s in the ultraviolet (UV) and/or visible regions of the spectrum, and electron beam radiation.

[0036] Adhesive articles of the present disclosure can optionally include a primer layer disposed between the first major surface of the backing layer and the adhesive layer. The primer layer material includes at least one polymer selected from the group consisting of chlorinated polyolefins, acrylics, polyurethanes, fatty esters, polyamides, rubber, and combinations thereof. Non limiting examples of commercially available polymers for use as primer component include NEOREZ R-600 and NEOREZ R-960 available from DSM, Eastman CP-343-1 and CP-343-3 available from Eastman Chemical Products, Inc. and Tramaco Trapylen 814 HS from Tramaco and MACROMELT 6240 available from Henkel.

[0037] Some embodiments of the acrylic adhesive are capable of forming an acrylic adhesive assembly that exhibits a peel adhesion value of less than 100 g/12 mm according to ASTM D3330 test method A and peel angle of 180, peel rate 300 mm/min. The Peel Adhesion Test is noted below in the Examples. [0038] The adhesive assembly may also possess other desirable characteristics, for example, the adhesive assembly may comprise one or more of (i) a loop tack value greater than 80 g/25 mm according to ASTM D6195-03 test method B, and (ii) shear value of greater than 10,000 shear min according to ASTM D3654 test procedure A. In certain embodiments, the shear value may be greater than 12,000 shear min, greater than 15,000 shear min, or even greater than 17,000 shear min.

[0039] The acrylic adhesives balance of adhesive properties to enable sufficient shear holding strength and then subsequently permit the clean removal of the acrylic adhesive is not the only defining attribute of the composition of this disclosure. The acrylic adhesive has at least a 1 second creep compliance of greater than lxl0^"6 cm²/dyne. [0040] The acrylic PSA's disclosed herein are well suited for other application areas that include, for example, tapes/films for surface protection, reclosable labels and tapes, skin and wound tapes.

[0041] In some embodiments, the backing for the acrylic adhesive includes a release coating Release coatings can be advantageous, for example, when an adhesive article of the present disclosure in wound onto itself in roll form, and later needs to be unwound without leaving residual adhesive on the outer surface of the backing layer. Examples of release-coating materials are well known in the art and include, by way of example, the release component can be selected from the group consisting of an acrylic polymeric resin, an urethane containing polymeric resin, and combinations thereof. The release coating of the present disclosure includes less than 0.5 percent by weight silicone, or less than 0.1 percent by weight silicone, or the release coating is even silicone-free.

[0042] The coating thickness and weight of the presently described release coatings are similar to those described in U.S. Pat. No. 2,532,011, the disclosure of which is incorporated herein in its entirety by reference. For example, the release coating can form a very thin layer, e.g. less than one-hundred- thousand of an inch thick, constituting a "molecular film" (i.e. a film which has a thickness of only a relatively few molecules). It has been found that coating weights of from about 0.2 to about 1.0 lb. per 1000 square yards (from about 110 grams to about 540 grams per 1000 square meters) of polymeric film backing give the results desired. Thicker coatings can be used if so desired.

[0043] In some embodiments, the backing layer for the acrylic adhesive includes a top coating varnish. Varnish can be advantageous, for example, to protect pre-printed artwork in the label or to increase the anchorage of thermal transfer ink. Additionally, top coating varnish can be used to decrease unwind force of linerless label.

[0044] Varnish can be selected from UV varnish, vinyl chloride copolymers, cellulosic, acrylic, polyurethane, polyamide, styrene, vinyl acetate, ketone, phenolic, epoxy, maleic, rosin ester, alkyd resins, or combinations thereof. Non-limiting examples of top coating varnish includes UV varnishes UV3000 and UV 3000-BG, available from Canoplus, and OVER VARNISH AF BOPP FREE C-40581, available from Vivacor.

[0045] Adhesive articles of the present disclosure can include label tape. It is well known to employ a printing device to print onto a label tape to define a label segment, and apply subsequently cut label segments to an article of interest, such as a box. Such printing methods are described, for example, in U.S. Patent No. 6,652, 172, the description of which is incorporated herein by reference. It will be understood that the article of interest can assume a wide variety of forms, including containers, packages, finished good articles, flats, etc. The term "label tape" is in general reference to an adhesive article of the present disclosure that is linerless; that can be supplied in a roll (such as a self-wound roll); and that is not pre-cut. Because, in roll form, the label tape typically does not include printing and is supplied as a continuous web, the terms "web of linerless tape" or simply "tape" can be used interchangeably with the term "label tape". The term "label segment" is used to mean a portion of a continuous web of linerless label tape that can convey information (such as by printing) and that can be affixed to a surface. Label segments include the tape after it is printed (if it is to be printed), both before and after it is severed from a remainder of the continuous web.

[0046] One system for printing variable information involves thermal transfer ink printing onto labels using an ink ribbon and a special heat transfer print head. A computer controls the print head by providing input to the head, which heats discrete locations on the ink ribbon. The ink ribbon directly contacts the label so that when a discrete area is heated, the ink melts and is transferred to the label. Another approach using this system is to use labels that change color when heat is applied (direct thermal labels). In another system, variable information is directly printed onto a box or label by an inkjet printer including a print head. A computer can control the ink pattern sprayed onto the box or label.

[0047] Both thermal transfer and inkjet systems produce sharp images. Inkjet systems include piezo, thermal, continuous, and drop-on-demand. With both inkjet and thermal transfer systems, the print quality depends on the surface on which the ink is applied. It appears that the best system for printing variable information is one in which the ink and the print substrate can be properly matched to produce a repeatable quality image, especially bar codes, that must be read by an electronic scanner with a high degree of reliability. [0048] As the web of linerless tape is pulled or extended from the supply roll, the adhesive side is exposed and will readily adhere to contacted surfaces, in particular, guide components associated with the printing device. A common difficulty encountered in the handling of linerless label tape is "wraparound", whereby the web adheres to and wraps around a roller otherwise in contact with the adhesive side. This highly undesirable situation leads to printer malfunctions, such as misprinting, tape jams, etc. [0049] EMBODIMENTS Selected Embodiments

The following embodiments, designated by letter and number, are intended to further illustrate the present disclosure but should not be construed to unduly limit this disclosure.

Al . An adhesive article comprising an acrylic adhesive assembly having a backing layer having a first major surface and a second major surface opposite the first major surface, and an acrylic adhesive layer disposed on at least a portion of the first major surface of the backing layer, wherein the acrylic adhesive is the reaction product of:

(1) an acrylic acid ester of monohydric alcohol having 5 to 10 carbon atoms; and

(2) a non-polar acrylic monomer having a solubility parameter of less than 9.2 as measured by the Fedors method using a homopolymer of the non-polar acrylic monomer, wherein the reaction product has side chain crystallinity

wherein the acrylic adhesive comprises less than 0.5 percent of silicone by weight, and

wherein the backing layer comprises less than 0.5 percent of silicone by weight.

A2 The adhesive article of embodiment Al, wherein the acrylic adhesive comprises a pressure sensitive adhesive or a hot melt adhesive. A3. The adhesive article according to embodiment Al or A2, further comprising a primer layer disposed between the acrylic adhesive layer and the backing layer, wherein the primer layer comprises less than 0.5 percent of silicone by weight.

A4. The adhesive article of any of embodiments A 1 to A3, wherein the adhesive article is linerless.

A5. The adhesive article of any of embodiments Al to A4, wherein the adhesive article is wound directly upon itself in roll form.

A6. The adhesive article of any of embodiments Al to A5, wherein the adhesive article exhibits a peel adhesion value of less than 150 g/12 mm when tested according to the ADHESION TO BACKING test method.

A7. The adhesive article of any of embodiments Al to A6, wherein the acrylic adhesive layer further comprises a crosslinking agent or a tackifier.

A8. The adhesive article of any of embodiments Al to A7, wherein the acrylic acid ester of monohydric alcohol comprises 2-ethylhexyl acrylate, iso-octyl acrylate , 2-octyl acrylate, n-octyl acrylate, nonyl acrylate, hexyl acrylate, heptyl acrylate, 2-heptyl acrylate, ethylbutyl acrylate, 3-methylbutyl acrylate, fusel oil acrylate and combinations thereof.

A9. The adhesive article of any of embodiments Al to A8, wherein the acrylic adhesive has a biobased content of at least 25% by weight according to ASTM D6866-10, method B.

A 10. The adhesive article of any of embodiments Al to A9, wherein the non-polar acrylic monomer comprises an octadecyl acrylate, an octadecyl methacrylate, a cyclodecyl acrylate, a cyclohexyl acrylate, a hexadecyl acrylate, an isobornyl acrylate, a lauryl acrylate, a lauryl methacrylate or combinations thereof.

Al l . The adhesive article any of embodiments Al to A 10, wherein the reaction product exhibits a fusion enthalpy of at least 2.5 J/g, at least 5.5 J/g, or at least 6.0 J/g.

A 12. The adhesive article of any of embodiments Al to Al l, wherein the non-polar acrylic monomer has an alkyl group from about 12 to about 26 carbon atoms.

A13. The adhesive article of any of embodiments Al to A 12, wherein the adhesive article exhibits a peel adhesion value of less than 100 g/12 mm according to ASTM D3330 test method A and peel angle of 180, peel rate 300 mm/min on a stainless steel pane conforming to Type 302 of Specification A666.

A14. The adhesive article of any of embodiments Al to A13, further comprising one or more of (i) a loop tack value greater than 80 g/25 mm according to ASTM D6195-03 test method B, and (ii) shear value of greater than 10,000 shear, min according to ASTM D3654 test procedure A.

A15. The adhesive article of any of embodiments Al to A 14, wherein the backing layer comprises a polyolefin.

A16. The adhesive article of any of embodiments Al to A15, wherein the backing layer comprises, non-oriented polypropylene, mono-oriented polypropylene, biaxially-oriented polypropylene, polyethylene, or combinations thereof.

A 17. The adhesive article of any of embodiments Al to A 16, wherein the backing layer comprises a non-oriented polypropylene.

A18. The adhesive article of any of embodiments Al to A 17, wherein the adhesive assembly comprises 25 weight percent or more of plant based materials. A19. The adhesive article of any of embodiments Al to A18, wherein the backing layer has a thickness of at least about 60 micrometers.

A20. The adhesive article of any of embodiments Al to A19, wherein the backing layer has a flexural rigidity is in the range from 0.8* 10^~2ΐο 3. O x 10^"2N mm.

A21. The adhesive article of any of embodiments Al to A20, further comprising a release coating disposed on the second major surface of the backing layer.

A22. The adhesive article of embodiment A21, wherein the release coating comprises polyurethane.

A22. The adhesive article of any one of embodiments A21 or A22, wherein the release coating is printable.

A23. The adhesive article of any of embodiments Al to A20, further comprising a top coating varnish disposed on the second major surface of the backing layer.

A24. The adhesive article of embodiment A23, wherein the top coating varnish is printable.

Ml. A method of printing a label, comprising :

(1) providing an adhesive article of an of the embodiments Al to A24; and

(2) printing indicia onto the second major surface of the adhesive article.

M2. The method of embodiment Ml, wherein the printing comprises any of thermal transfer ink printing or inkjet printing.

M3. A method of making an adhesive article, comprising:

providing an adhesive composition comprising:

(2) a non-polar acrylic monomer having a solubility parameter of less than 9.2 as measured by the Fedors method using a homopolymer of the non-polar acrylic monomer, wherein the reaction product has side chain crystallinity;

wherein the adhesive composition comprises less than 0.5 percent by weight silicone; and coating the adhesive composition onto a backing layer.

M4. The method of embodiment M3, wherein the adhesive composition is cured using ultraviolet irradiation after being coated onto the backing layer. EXAMPLES [0050] TEST PROCEDURES

[0051] Peel Adhesion:

Peel adhesion was measured following the procedure outlined in ASTM D 3330/D 3330M-04, "Standard Test Method for Peel Adhesion of Pressure-Sensitive Tape." Samples of adhesive tapes measuring 12 mm in width and 20 cm in length were cut and adhered to a Type 302 stainless steel plate. A 2 kg roller was rolled over each sample twice. The stainless steel plate was cleaned prior to adhering the adhesive tape by wiping the plate with isopropyl alcohol using a tissue paper. The adhesive tape remained adhered to the plate for about fifteen minutes before the force required to peel the tape was measured using an IMASS Adhesion Tester SP-2100 (available from Imass, Inc., Hingham, Mass) equipped with a 2 kg load cell. Peel angle was 180 degrees. Peel adhesion was measured in grams per 12 mm and at speeds of 300 millimeters per minute. Measurements were done in triplicate. The average peel adhesion is reported in gram/ 12 mm (g/12 mm).

[0052] ADHESION TO BACKING TEST METHOD:

Labels were adhered to Type 302 stainless steel plates using double coated adhesive tape. Samples 12 mm wide by 20 cm long of the same adhesive label were cut and adhered to the backing of the label, so that the adhesive layer of the label contacted the backing of the label. A 2 kg roller was then rolled onto the construction twice. The samples were subsequently aged for 72 hours at 50°C in a laboratory oven.

Samples were conditioned at 25 °C and 50% relative humidity (RH) for 24 hours. The force required to peel the adhesive label from the backing was measured using the IMASS Adhesion Tester SP-2100 equipped with a 2 kg load cell. Peel adhesion was measured in grams per 12 mm at a speed of 300 mm per minute at a 90 degree angle. Measurements were done at least in triplicate. The average peel adhesion is reported in g/12mm in Table 2.

[0053] Loop Tack:

Loop tack was measured following the test method B procedure described in ASTM D6195-03, "Standard Test Methods for Loop Tack". Samples of adhesive tape measuring 25 mm by 100 mm were cut and a loop was formed and attached to a mobile arm of a Loop Tack tester (LT-500, Chemlnstruments, Inc.). The force required to remove the tape at 300 mm/min was measured in grams per 25 mm. Measurements were done in triplicate. Average loop tack is reported in gram/25 mm (g/25 mm). [0054] Breaking Strength and Elongation:

Breaking strength and elongation was measured according to test method A or C described in ASTM D3759/D3759M. Samples of 12 mm wide by 20 cm long of adhesive label were cut and mounted between two clamps of an Instron Machine, MODEL 5965, equipped with a 5 kg load cell. For BOPP film samples a 10 cm gauge length was used and for NOPP film samples a 5 cm gauge length. Separation rate was 30 cm/min The breaking strength was measured in kgf/12 mm and elongation in %.

[0055] Inherent Viscosity

The test method for Inherent Viscosity is based on a comparison of the cinematic viscosity of a diluted solution of the adhesive and the pure solvent used to prepare this diluted solution. The solvent used was ethyl acetate. This cinematic viscosity was measured using an Ostwald-Fenske viscometer, using an automatic equipment from Lauda DR. R. Wobser GMBH & Co. KG, from Germany, model Lauda Viscotemp 15. The solution was prepared and 10 ml of this solution was added to the equipment and it measured the cinematic viscosity, in seconds, for this solution. The adhesive solution was then replaced by pure solvent and the viscosity was measured. The polymer solution concentration was also measured using an oven @ 120 °C. The equipment calculated the Inherent Viscosity based on the following theoretical relationship:

The inherent viscosity is defined as:

Where C is the mass concentration of the polymer (g/dL) and is the relative viscosity , which is defined as

Where V is the viscosity of the solution and ¾8 is the viscosity of the pure solvent. The unit of inherent viscosity is dL/g.

[0056] Modulated® Differential Scanning Calorimeter (MDSC):

The specimens were prepared for thermal analysis by weighing and loading the material into TA Instruments aluminum DSC sample pans. The specimens were analyzed using the TA Instruments Q2000 Modulated® Differential Scanning Calorimeter (MDSC) utilizing a heat-cool-heat method in temperature modulated mode (-90 to 200°C at 4°C/min. with a modulation amplitude of ±0.64°C and a period of 60 sec).

After data collection, the thermal transitions were analyzed using the TA Universal Analysis program. Any peak transitions were evaluated using the heat flow (HF), reversing heat flow (REV HF) or non-reversing heat flow (NR HF) curves. Peak area values and/or peak minimum / maximum temperatures are also determined; peak integration results are normalized for sample weight and reported in J/g.

[0057] REMOVABILITY TESTS

Labels were adhered to INOX, painted and polystyrene substrates, from Electrolux appliance products, and aged at 70 °C for 72 hours. Samples were conditioned at room temperature for 24 hours, then, label was removed from the substrate and visual inspected for adhesive transfer.

[0058] PRINTABILITY TESTS

Labels were printed on a Thermal Transfer Printer GT408e with linerless kit, available from Sato America, using a resin-wax ribbon, available from 3M Brazil. Thermal transfer of ink to the label and dispensability of labels were evaluated.

[0059] MATERIALS

Chemical Name Abbreviation Supplier Location

2-Ethylhexyl Acrylate 2 EH A BASF Corp. Florham Park,

NJ

Butyl Acrylate BA BASF Corp. Florham Park,

NJ

Octadecyl Acrylate ODA Akzo Nobel Amsterdam,

N.V. Netherlands

Isobornyl Acrylate IBA San Esters Corp. New York, NY

Ethyl Acetate EtOAc Rhodia, Solvay Lyon, France

Group

Toluene Toluene Ipiranga Rio Grande Do

Sul, Brazil

Azobisisobutyronitrile VAZO 64 / E. I. du Pont de Wilmington,

AIBN Nemours and DE

Company

Acryloxyethoxybenzophenone AEBP 3M Company St. Paul, MN

Acryloxybenzophenone ABP¹

Isooctylthioglicolate IOTG Evans Teaneck, NJ

Chemetics LP

Biaxially-Oriented Polypropylene BOPP Vitopel Sao Paulo,

Film Brazil

Non-oriented polypropylene Film NOPP 3M Company Itapetininga, Chemical Name Abbreviation Supplier Location

Brazil

OVER VARNISH AF BOPP VARNISH VIVACOR Diadema,

FREE C-40581 Brazil

Ribbon wax-resin Ribbon 3M Brazil Sumare,

Brazil

^l - ABP was produced according to the disclosure of U.S. Pat. No. 4,737,559 (Kellen et al.)

[0060] PREPARATION OF EXAMPLES

[0061] Preparation of Comparative Adhesive Composition 1 and 2

Ingredients were added to a 1000 ml four-necked reaction vessel, equipped with a stirrer, nitrogen line, condenser, and a PT100 thermocouple in the following order: acrylate monomers, ethyl acetate (ethyl ac), and, optionally, AEBP (50% solids in ethyl acetate) were charged. A slight nitrogen purge was placed in the solution and this solution reaction was heated to 62°C. When the temperature reached 62°C, a solution of 0.20 grams of VAZO 64 in 5 grams of ethyl acetate was added to the solution reaction. This solution was kept in reaction for about 24 hours, and a 98-99% conversion was obtained. Inherent viscosity of the adhesive was measured. Ingredients (reported in grams) and inherent viscosity (IV) of Comparative Adhesive Composition 1 are shown, respectively, in Tables 1 and 2, below.

[0062] Comparative Adhesive Composition 2 was produced in the same manner as Comparative Adhesive Composition 1, except that the amount of each ingredient were varied as reported in Table 1.

[0063] Comparative Adhesive Composition 1 is similar to the adhesive composition described in Example 25 of U.S. Patent No. 5,552,451 (Everaerts, et al). Comparative Adhesive Composition 2 is similar to the adhesive composition described in Example 17 of U.S. 5,552,451.

[0064] Preparation of Adhesive Composition 1

Adhesive Composition 1 was prepared as described above for Comparative Adhesive Composition 1, except that the following ingredients/conditions were used: (i) a solution of ODA in toluene (ODA sol.) (45.2 % solids); (ii) 0.35g of VAZO 64 in 5 grams of ethyl acetate; and (iii) the reaction solution was heated to a temperature of about 58°C. Ingredients (reported in grams) and inherent viscosity (IV) of Adhesive Composition 1 are shown, respectively, in Tables 1 and 2, below. TABLE 1

ABP is a 25% solids solution in ethyl acetate

TABLE 2

[0065] MODULATED DIFFERENTIAL SCANNING CALORIMETER (MP SO Results

Peak transitions were evaluated using the heat flow (HF), reversing heat flow (REV HF) or non-reversing heat flow (NR HF) curves. Peak area values and/or peak minimum / maximum temperatures are also determined; peak integration results are normalized for sample weight and reported in J/g. Fusion enthalpy results are reported in Table 3. Comparative adhesive compositions 1 and 2, with fusion enthalpy results below 2.5 J/g, are generally considered amorphous materials for purposes of this disclosure. They did not exhibit adhesion characteristics comparable to Composition 1.

TABLE 3

[0066] Preparation of Printable Release Component 1

Printable Release Component 1 comprised a polyurethane polymer prepared as follows: In a four neck resin flask equipped with N2 inlet, a dean stark trap, a thermocouple and an agitator was charged 34.6 g 50% hydrolyzed polyvinyl alcohol (PVOH) available from 3M and 180 g xylene. The mixture was heated to 135°C to azeotrope water to be certain that the resulting dispersion does not contain more than 0.2% water. To the dispersion was added 64 g octadecyl isocyanate. The resulting mixture was heated at 137°C for about 9 hrs. Or until isocyanate is less than 0.5 wt.%. The solids are measured to be 35 wt.%. To this solution 1693 g toluene was added to obtain 5 wt.% solution in a blend of xylene and toluene.

[0067] COMPARATIVE EXAMPLES 1-2 and EXAMPLE 1

Adhesive tapes were prepared using the following procedure: adhesive compositions were manually coated onto a biaxially oriented polypropylene backing film (BOPP, clear, 40 micron thick) using a coating knife and dried for 15 minutes in a laboratory oven set at a temperature of about 65°C. After the drying period, the adhesive coating weight was between about 14 and about 16 g/m². The adhesive tape was cured using a Fusion Curing System Unit, Model VPS/1600 (from Fusion Systems Corp, Rockville, MD) with a total energy of 50 mJ/cm² to crosslink the adhesive. The Fusion Curing System Unit comprised one lamp with an H bulb with a power supply of 300 Watts/inch (118.1 watts/cm). The UVC radiation dose was controlled by the power settings of the device, the conveyor speed setting, and the number of passes of the adhesive under the ultraviolet light. [0068] EXAMPLE 2

Adhesive tape was prepared using the following procedure: Printable release component 1 was coated in a laboratory coater onto a Corona treated non-oriented polypropylene backing film (NOPP, 55 g/m²) using a gravure roll and dried in an oven to evaporate the solvent at 90 °C. After that, the adhesive composition was coated onto the opposite side of the non-oriented polypropylene backing film using a coating knife and dried to evaporate the solvent in an oven at 70 °C. After drying, the adhesive coating weight was between 15 and 17 g/m². The adhesive tape was cured using germicidal (GEMS) UVC irradiation of 150 mJ/cm² to crosslink the adhesive.

[0069] EXAMPLE 3

Adhesive tape was prepared using the following procedure: adhesive composition was coated in laboratory coater onto a biaxially-oriented polypropylene backing film (BOPP, clear, 40 micrometer thickness) using a coating knife and dried to evaporate the solvent in an oven at 70 °C. After drying, the adhesive coating weight was between 15 and 17 g/m². The adhesive tape was cured using germicidal (GEMS) UVC irradiation of 200 mJ/cm² to crosslink the adhesive.

[0070] EXAMPLE 4

Adhesive tape was prepared using the following procedure: OVER VARNISH AF BOPP FREE C-40581, available from Vivacor, was coated in a Corona treated biaxially oriented polypropylene film (BOPP, white, 30 micrometer thickness) using a rubber roll and dried in an oven to evaporate the solvent at 90 °C. After that, the adhesive composition was coated onto the opposite side of the BOPP film using a coating knife and dried to evaporate the solvent in an oven at 70 °C. After drying, the adhesive coating weight was between 13 and 15 g/m². The adhesive tape was cured using germicidal (GEMS) UVC irradiation of 300 mJ/cm² to crosslink the adhesive.

[0071] EXAMPLE 5

Adhesive tape was prepared using the following procedure: adhesive composition was coated in laboratory coater onto a Corona treated non-oriented polypropylene backing film (NOPP PURPLE, 62 g/m²) using a coating knife and dried to evaporate the solvent in an oven at 70 °C. After drying, the adhesive coating weight was between 7 and 9 g/m². The adhesive tape was cured using germicidal (GEMS) UVC irradiation of 200 mJ/cm² to crosslink the adhesive.

[0072] EXAMPLE 6

Adhesive tape was prepared using the following procedure: adhesive composition was coated in laboratory coater onto a non-oriented polypropylene backing film (NOPP PURPLE, 62 g/m² micrometer thickness) using a coating knife and dried to evaporate the solvent in an oven at 70 °C. After drying, the adhesive coating weight was between 13 and 15 g/m². The adhesive tape was cured using germicidal (GEMS) UVC irradiation of 200 mJ/cm² to crosslink the adhesive.

[0073] Comparative Examples 1 and 2 were prepared using, respectively, Comparative Adhesive Compositions 1 and 2. Examples 1 to 6 were prepared using Adhesive Composition 1.

[0074] Test Results

Tensile strength and elongation of PP films used in examples and comparative examples were measured according to procedure above and reported on Table 4. TABLE 4

[0075] Comparative Examples 1-6, and Examples 1 and 2 were submitted to peel adhesion measured at a peel angle of 180 degrees and peel rate of 300 mm/min, adhesion to the backing and loop tack, using the procedures described above. Results are reported in Table 5, below. TABLE 5

[0076] Examples 2 to 6 were adhered to INOX, painted and polystyrene substrates, from Electrolux appliance products, and aged following the procedures described above in removability tests. Adhesive transfer to the substrate is reported as "small" and "none", wherein "small" means that a small amount of adhesive transferred to the substrate and "none" means clean removal. Results are reported in Table 6, below.

[0077] Table 6

[0078] Example 1 to 6 were submitted to printing in a Thermal Transfer Printer GT408e with linerless kit, available from Sato America according to the procedure described above. Printability and dispensability of Examples 2 to 6 are reported in Table 7 wherein "Good" means that printed artwork is well defined without visual defects, "OK" means that label was correctly dispensed and "failed" means that label was not dispensed and wrap-around of the platen roller.

[0079] Table 7

Example Printability Label dispenser

Example 2 Good OK

Example 3 Good OK

Example 4 Good Failed

Example 5 Good Failed

Example 6 Good Failed

Claims

What is claimed is:

1. An adhesive article comprising an acrylic adhesive assembly having a backing layer having a first major surface and a second major surface opposite the first major surface, and an acrylic adhesive layer disposed on at least a portion of the first major surface of the backing layer, wherein the acrylic adhesive is the reaction product of:

2. The adhesive article of any of the preceding claims, wherein the acrylic adhesive comprises a pressure sensitive adhesive or a hot melt adhesive.

3. The adhesive article according to any of the preceding claims, further comprising a primer layer disposed between the acrylic adhesive layer and the backing layer, wherein the primer layer comprises less than 0.5 percent of silicone by weight.

4. The adhesive article of any of the preceding claims, wherein the adhesive article is linerless.

5. The adhesive article of any of the preceding claims, wherein the adhesive article is wound directly upon itself in roll form.

6. The adhesive article of any of the preceding claims, wherein the adhesive article exhibits a peel adhesion value of less than 150 g/12 mm when tested according to the ADHESION TO BACKING test method.

7. The adhesive article of any of the preceding claims, wherein the acrylic adhesive layer further comprises a crosslinking agent or a tackifier.

8. The adhesive article of any of the preceding claims, wherein the acrylic acid ester of monohydric alcohol comprises 2-ethylhexyl acrylate, iso-octyl acrylate , 2-octyl acrylate, n-octyl acrylate, nonyl acrylate, hexyl acrylate, heptyl acrylate, 2-heptyl acrylate, ethylbutyl acrylate, 3-methylbutyl acrylate, fusel oil acrylate and combinations thereof.

9. The adhesive article of any of the preceding claims, wherein the acrylic adhesive has a biobased content of at least 25% by weight according to ASTM D6866-10, method B.

10. The adhesive article of any of the preceding claims, wherein the non-polar acrylic monomer comprises an octadecyl acrylate, an octadecyl methacrylate, a cyclodecyl acrylate, a cyclohexyl acrylate, a hexadecyl acrylate, an isobornyl acrylate, a lauryl acrylate, a lauryl methacrylate or combinations thereof.

11. The adhesive article of any of the preceding claims, wherein the reaction product exhibits a fusion enthalpy of at least 2.5 J/g.

12. The adhesive article of any of the preceding claims, wherein the non-polar acrylic monomer has an alkyl group from about 12 to about 26 carbon atoms.

13. The adhesive article of any of the preceding claims, wherein the adhesive article exhibits a peel adhesion value of less than 100 g/12 mm according to ASTM D3330 test method A and peel angle of 180, peel rate 300 mm/min on a stainless steel pane conforming to Type 302 of Specification A666.

14. The adhesive article of claim 13, further comprising one or more of (i) a loop tack value greater than 80 g/12 mm according to ASTM D6195-03 test method B, and (ii) shear value of greater than 10,000 shear, min according to ASTM D3654 test procedure A.

15. The adhesive article of any of the preceding claims, wherein the backing layer comprises a polyolefin.

16. The adhesive article of claim 15, wherein the backing layer comprises a non-oriented polypropylene, mono-oriented polypropylene, biaxially-oriented polypropylene, polyethylene, or combinations thereof.

17. The adhesive article of any of the preceding claims, wherein the backing layer comprises a non- oriented polypropylene.

18. The adhesive article of any of the preceding claims, wherein the adhesive assembly comprises 25 weight percent or more of plant based materials.

19. The adhesive article of any of the preceding claims, further comprising a release coating disposed on the second major surface of the backing layer.

20. The adhesive article of claim 19, wherein the release coating is printable.

21. The adhesive article of any of the preceding claims, further comprising a varnish disposed on second major surface of the backing layer.

22. The adhesive article of claim 21, wherein the varnish coating is printable.