Self-priming optically clear adhesive

Abstract

A self-priming adhesive article, the self-priming adhesive article comprising: a release liner, the release liner having a release surface; an adhesion promoting layer on the release surface; and an optically transparent adhesive layer in contact with the adhesion promoting layer. An adhesive force between the adhesive layer and the adhesion promoting layer is higher than an adhesive force between the adhesion promoting layer and the release liner such that the adhesion promoting layer remains adhered to a surface of the adhesive layer when removed from the release liner. The adhesive article may be prepared by applying an adhesion promoting layer onto a release liner and applying an adhesive layer onto the adhesion promoting layer; alternatively, an adhesion promoting layer is applied to the surface of the adhesive layer and then the adhesive layer coated with the adhesion promoting layer is brought into contact with the release liner.

Description

Summary of the invention

[0001] Adhesive articles and methods for preparing adhesive articles are disclosed herein. In some embodiments, the adhesive article includes: a release liner having a first major surface and a second major surface, wherein at least the second major surface includes a release surface; an adhesion promoting layer having a first major surface and a second major surface, wherein the first major surface of the adhesion promoting layer contacts the second major surface of the release liner; and an optically clear adhesive layer having a first major surface and a second major surface, wherein the first major surface of the optically clear adhesive layer contacts the second major surface of the adhesion promoting layer. The adhesion between the optically clear adhesive layer and the adhesion promoting layer is higher than the adhesion between the adhesion promoting layer and the release liner, so that when the optically clear adhesive layer is removed from the release liner, the adhesion promoting layer remains adhered to the surface of the optically clear adhesive layer. Like the adhesive layer, the adhesion promoting layer is optically transparent. In some embodiments, the article also includes an additional release liner or substrate disposed on the optically clear adhesive layer.

[0002] Also disclosed is a method for preparing an adhesive article. In some embodiments, the method includes: providing a release liner, wherein the release liner has a first major surface and a second major surface, and at least the second major surface includes a release surface; providing an adhesion-promoting composition; disposing the adhesion-promoting composition on the second major surface of the release liner to form an adhesion-promoting layer on the second major surface of the release liner, wherein the adhesion-promoting layer has a first major surface and a second major surface, and the first major surface of the adhesion-promoting layer is in contact with the release surface of the release liner; providing an optically clear adhesive or a precursor mixture capable of forming an optically clear adhesive; disposing the optically clear adhesive or the precursor mixture on the second major surface of the adhesion-promoting layer to form an optically clear adhesive layer, the optically clear adhesive layer having a first major surface and a second major surface, wherein the first major surface of the optically clear adhesive layer is in contact with the second major surface of the adhesion-promoting layer. The adhesion between the optically clear adhesive layer and the adhesion-promoting layer is higher than the adhesion between the adhesion-promoting layer and the release liner, so that when the optically clear adhesive layer is removed from the release liner, the adhesion-promoting layer remains adhered to the surface of the optically clear adhesive layer.

[0003] In some embodiments, a method for preparing an adhesive article includes: providing a release liner, wherein the release liner has a first major surface and a second major surface, and wherein at least the second major surface includes a release surface; providing an adhesion promoting composition; providing an optically clear adhesive layer, wherein the optically clear adhesive layer has a first major surface and a second major surface; disposing the adhesion promoting composition on the first major surface of the optically clear adhesive layer to form an adhesion promoting layer on the first major surface of the optically clear adhesive layer, wherein the adhesion promoting layer has a second major surface in contact with the first major surface of the optically clear adhesive layer and an exposed first major surface; disposing the optically clear adhesive layer having the adhesion promoting layer on the release surface of the release liner so that the first major surface of the adhesion promoting layer contacts the release surface of the release liner. The adhesion between the optically clear adhesive layer and the adhesion promoting layer is higher than the adhesion between the adhesion promoting layer and the release liner, so that when the optically clear adhesive layer is removed from the release liner, the adhesion promoting layer remains adhered to the surface of the optically clear adhesive layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The present application may be more fully understood by referring to the following detailed description of various embodiments of the present disclosure in conjunction with the accompanying drawings.

[0005] Figure 1 is a cross-sectional view of an adhesive article of the present disclosure. DETAILED DESCRIPTION

[0006] A wide variety of optical articles are being developed for a wide variety of uses. Among optical articles are articles and devices that include multiple layers. Typically, these multiple layers are attached to each other with adhesive layers. Because the adhesive layer is in the light path, the optical properties of the adhesive layer are important considerations in the assembly of the optical article.

[0007] Optically clear adhesives (hereinafter referred to as "OCAs") are widely used in a variety of articles and have increasingly stringent performance requirements. Not only must these adhesives have the desired optical properties and maintain these properties under a variety of environmental conditions, but they must also perform the function of an adhesive, i.e., bonding two substituents together. In many cases, OCAs are pressure sensitive adhesives, in other cases, OCAs are heat activated adhesives.

[0008] The requirements for optical products are getting higher and higher. For example, many optical products have increasingly complex shapes and are also intended to be bent, so for these uses, adhesives that are flexible and adhere to surfaces of various shapes are required. Surfaces of various shapes include a variety of non-planar surfaces.

[0009] Double-sided tape, also known as "transfer tape", is an adhesive tape having adhesive on both exposed surfaces. In some transfer tapes, the exposed surfaces are just the two surfaces of a single adhesive layer. Typically, the transfer tape is laminated to at least one release liner, or between two release liners. An advantage of transfer tape is that it can be used to form a variety of adhesive articles. The transfer tape can be laminated to a backing or film layer to form a tape, which can then be further laminated to another surface. A particularly useful use of transfer tape is to laminate two substrates together by laminating to one substrate, removing the release liner from the unlaminated adhesive surface, and placing a second substrate onto the exposed adhesive surface.

[0010] Because a wide variety of substrates or films are used in optical articles and devices, it is often difficult for a single adhesive to adhere to a wide variety of substrates or films. This situation is further complicated by the fact that substrates or films may also have a variety of shapes or configurations and may be designed to be flexible, such as bendable, and the adhesive not only needs to adhere to these surfaces, but also needs to maintain the desired optical properties.

[0011] One method for improving the adhesion of an adhesive layer to a substrate surface is to pretreat the substrate surface with a primer layer. Primers are well known in the coating art and are relatively thin layers that are applied to a surface to change the surface chemistry, thereby making the surface more susceptible to adhesion. The disadvantage of using a primer layer is that the use of a primer adds an additional step in the assembly of the device. In addition, primers are typically provided in a solvent (organic solvent or water), so a drying step is also required. This can be problematic in a product assembly plant because the application and drying of the primer layer requires special equipment and precautions. This is especially true if a solvent-based primer is used and drying is required.

[0012] In the present disclosure, a method of priming is described in which a primer layer is applied to the surface of an OCA. In many embodiments, the primer is applied to the surface of a release liner, and the OCA is disposed on a release liner having a primer on its surface, so that when the OCA is removed from the release liner, at least some of the primer is transferred to the surface of the OCA. In this way, the primer is also applied when the OCA is applied to the surface. In other embodiments, the primer layer is disposed on the surface of the OCA before the OCA is disposed on the release liner.

[0013] There are many advantages to this method. In this way, the primer can be delivered to the surface without the need for an additional priming step. In addition, as described above, the difficulties of applying the primer in the assembly plant are avoided because the primer is applied when the article is formed and is therefore applied in a factory with equipment and expertise that can safely carry out the application and / or drying of the primer layer.

[0014] As used herein, the term "adhesive" refers to a polymer composition that can be used to adhere two adherends together. Examples of adhesives are pressure sensitive adhesives and heat activated adhesives.

[0015] Those of ordinary skill in the art are well aware that pressure-sensitive adhesive compositions have properties including: (1) strong and lasting tack, (2) adhesion with finger pressure, (3) sufficient ability to remain on an adherend, and (4) sufficient cohesive strength to cleanly remove from an adherend. It has been found that materials that work well as pressure-sensitive adhesives are polymers that are designed and formulated to exhibit the desired viscoelastic properties, thereby achieving a desired balance of tack, peel adhesion, and shear holding power. Achieving the proper balance of properties is not a simple approach.

[0016] Heat activated adhesives are not tacky at room temperature but become tacky and able to bond to substrates at elevated temperatures. g (glass transition temperature) or melting point (T m ) is usually higher than room temperature. When the temperature rises above T g or T m When the storage modulus decreases, the adhesive becomes tacky.

[0017] As used herein, the term "self-priming" refers to an adhesive layer having a continuous or discontinuous layer of adhesion promoting material on at least one adhesive surface. The adhesion promoting material promotes the adhesion of the adhesive layer to the substrate surface, so that the adhesion of the adhesive layer is increased relative to the adhesion of the adhesive layer itself without the adhesion promoting material, and wherein no primer or adhesion promoting material is applied to the substrate surface.

[0018] The term "(meth)acrylate-based" refers to polymers containing at least a majority of (meth)acrylate monomers. The term "(meth)acrylate" refers to monomeric acrylate or methacrylate esters of alcohols. Acrylate and methacrylate monomers or oligomers are collectively referred to herein as "(meth)acrylates".

[0019] As used herein, the term "siloxane" refers to a polymer or polymer unit comprising siloxane units. The terms silicone or siloxane are used interchangeably and refer to units having dialkyl or diaryl siloxane (-SiR2O-) repeating units.

[0020] The terms "room temperature" and "ambient temperature" are used interchangeably and refer to temperatures in the range of 20°C to 25°C.

[0021] As used herein, the terms "polymer" and "macromolecule" are consistent with their common usage in chemistry. Polymers and macromolecules are composed of many repeating subunits. As used herein, the term "macromolecule" is used to describe a group attached to a monomer that has multiple repeating units. The term "polymer" is used to describe the resulting material formed by a polymerization reaction.

[0022] The term "alkyl" refers to a monovalent group that is an alkane radical, which is a saturated hydrocarbon. The alkyl group may be linear, branched, cyclic, or a combination thereof, and typically has 1 to 20 carbon atoms. In some embodiments, the alkyl group contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, and ethylhexyl.

[0023] Unless otherwise indicated, the terms "optically clear" and "visibly transmissive" are used interchangeably and refer to articles, films or adhesives that have high light transmittance over at least a portion of the visible light spectrum (about 400 nm to about 700 nm). Typically, optically clear articles have a visible light transmittance of at least 90% and a haze of less than 10%.

[0024] Unless otherwise indicated, "optically transparent" refers to an adhesive or article that has high light transmittance and exhibits low haze (typically less than about 5%, or even less than about 2%) over at least a portion of the visible light spectrum (about 400 nm to about 700 nm). In some embodiments, the optically transparent article exhibits a haze of less than 1% at a thickness of 50 microns or even 0.5% at a thickness of 50 microns. Typically, the optically transparent article has a visible light transmittance of at least 95%, typically higher such as 97%, 98%, or even 99% or higher.

[0025] Disclosed herein are adhesive articles. The articles are disposed on a release liner. The adhesive articles can be transfer tapes in which the adhesive layer is disposed on a release liner or between two release liners, or they can be tape articles having an adhesive layer and a substrate.

[0026] In some embodiments, the adhesive article includes: a release liner having a first major surface and a second major surface, wherein at least the second major surface includes a release surface; an adhesion promoting layer having a first major surface and a second major surface, wherein the first major surface is in contact with the second major surface of the release liner; and an optically clear adhesive layer having a first major surface and a second major surface, wherein the first major surface of the optically clear adhesive layer is in contact with the second major surface of the adhesion promoting layer. The adhesion between the optically clear adhesive layer and the adhesion promoting layer is higher than the adhesion between the adhesion promoting layer and the release liner. This means that after the optically clear adhesive layer is removed from the release liner, the adhesion promoting layer remains adhered to the surface of the optically clear adhesive layer. Like the adhesive layer, the adhesion promoting layer is optically transparent. In many embodiments, the optically clear adhesive layer is a pressure sensitive adhesive, and in some embodiments, the optically clear adhesive layer is a heat activated adhesive.

[0027] Adhesive articles include release liners. In the field of adhesives, release liners are fully understood to be films or sheet products that make at least one surface anti-adhesive, and the at least one anti-adhesive surface refers to the surface on which the adhesive will not be firmly adhered. Typical release liners include those prepared by paper (e.g., kraft paper) or polymer materials (e.g., polyolefins such as polyethylene or polypropylene, ethylene vinyl acetate, polyurethane, polyester such as polyethylene terephthalate, etc., and combinations thereof). At least some release liners are coated with release agent layers, such as materials of organosilicon, fluorinated organosilicon or fluorocarbon-containing materials. Exemplary release liners include, but are not limited to, pads that can be commercially available from CP Film Company (CP Film, Martinsville, Va.) in Martinsville, Virginia, under the trade name "T-30" and "T-10", and the pads have organosilicon release coatings on polyethylene terephthalate films. Particularly suitable are silicone coated PET release liners available from SKC Haas as RF32N and RF02N.

[0028] The adhesive article also includes an optically clear adhesive (OCA). The OCA may be a pressure sensitive adhesive or a heat activated adhesive. Examples of suitable OCAs include (meth)acrylate pressure sensitive adhesives, (meth)acrylate-based pressure sensitive adhesives, polyolefin pressure sensitive adhesives, polyurethane pressure sensitive adhesives, silicone-based pressure sensitive adhesives, polyvinyl butyral heat activated adhesives, or combinations thereof. The pressure sensitive adhesive includes at least one polymer component and may additionally include additional components, such as tackifying resins, plasticizing resins, etc., as long as the additives do not interfere with the optical properties of the adhesive composition.

[0029] Each of these types of polymeric pressure-sensitive adhesives is well known in the adhesive field. Polyolefin pressure-sensitive adhesives, also known as poly(1-olefin) pressure-sensitive adhesives, are polymers or copolymers prepared from olefin monomers. The polymer may also include radiation-activatable functional groups grafted thereon, as described in U.S. Pat. No. 5,209,971 (Babu et al.). Polyurethane pressure-sensitive adhesives useful in the present disclosure include, for example, those disclosed in U.S. Pat. No. 3,718,712 (Tushaus); No. 3,437,622 (Dahl); and No. 5,591,820 (Kydonieus et al.).

[0030] In some embodiments, the pressure-sensitive adhesive includes a (meth) acrylate pressure-sensitive adhesive or a (meth) acrylate-based pressure-sensitive adhesive, which comprises: one or more (meth) alkyl acrylate monomers having 2-18 carbon atoms, and may contain one or more hydroxyl groups; and at least one reinforcing monomer. Such pressure-sensitive adhesives typically have a glass transition temperature of about -20°C or less. Examples of suitable (meth) alkyl acrylate monomers include, for example, isooctyl acrylate, 2-ethyl-hexyl acrylate, n-butyl acrylate, HEA (hydroxyethyl acrylate) and HEMA (hydroxyethyl methacrylate). Examples of reinforcing monomers include, for example, (meth) acrylic acid, (meth) acrylamide, ethylene vinyl acetate, N-vinyl pyrrolidone and styrene macromonomers.

[0031] Silicone pressure-sensitive adhesives generally include two main components of polymer or gel and tackifying resin. Polymer is generally high molecular weight polydimethylsiloxane or polydimethyldiphenylsiloxane, which contains residual silanol functional groups (SiOH) at the end of the polymer chain, or a block copolymer comprising polydiorganosiloxane soft segments and urea or oxamide end-capped hard segments. Tackifying resin is generally a three-dimensional silicate structure terminated by trimethylsiloxy (OSiMe3) and also comprising some residual silanol functional groups. The example of tackifying resin includes SR 545 (derived from General Electric Company, Silicone Resins Division (GeneralElectric Co., Silicone Resins Division), Waterford, New York) and MQD-32-2 (derived from Shin-Etsu Silicones of America, Inc., Torrance, California). The manufacture of typical silicone pressure-sensitive adhesives is described in U.S. Patent No. 2,736,721 (Dexter). The manufacture of siloxane urea segmented copolymer pressure-sensitive adhesives is described in U.S. Patent No. 5,214,119 (Leir et al.). Other materials, including pigments, plasticizers and fillers, may be added for special purposes. The amount of filler is generally 0 to 10 parts per 100 parts of silicone pressure-sensitive adhesive. Examples of fillers that can be used include zinc oxide, silicon dioxide, carbon black, pigments, metal powders and calcium carbonate. A particularly suitable class of siloxane-containing pressure-sensitive adhesives is those with oxamide-terminated hard segments, such as those described in U.S. Patent No. 7,981,995 (Hays) and U.S. Patent No. 7,371,464 (Sherman).

[0032] In some embodiments, the adhesive layer is at least partially formed of polyvinyl butyral. The polyvinyl butyral layer can be formed by a known water-based or solvent-based acetalization process in which polyvinyl alcohol and butyraldehyde are reacted in the presence of an acidic catalyst. In some cases, the polyvinyl butyral layer can include or be formed of polyvinyl butyral, which can be commercially available from Solutia Incorporated, of St. Louis, MO, under the trade name "BUTVAR" resin.

[0033] In some cases, the polyvinyl butyral layer can be prepared by mixing the resin and (optional) a plasticizer and extruding the mixed formulation through a sheet die. If a plasticizer is included, the polyvinyl butyral resin can include about 20 to 80 parts, or possibly about 25 to 60 parts of plasticizer per hundred parts of resin. Examples of suitable plasticizers include polyacid esters or polyol esters. Suitable plasticizers are triethylene glycol di(2-ethylbutyrate), triethylene glycol di(2-ethylhexanoate), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, hexyl cyclohexyl adipate, a mixture of heptyl and nonyl adipate, diisononyl adipate, heptyl nonyl adipate, dibutyl sebacate, polymeric plasticizers such as oil-modified sebacic alkyd, and mixtures of phosphates and adipates such as disclosed in U.S. Pat. No. 3,841,890 and adipates such as disclosed in U.S. Pat. No. 4,144,217.

[0034] Adhesive articles also include an adhesion promoting layer. Various adhesion promoters are suitable. Generally speaking, adhesion promoters include materials commonly referred to as "primer" or "tackifier". Primer and tackifier are materials applied on the surface as a thin coating and strongly adhere to the surface and provide modified surface chemistry for the surface. In some embodiments, adhesion promoters include polyamides, poly (meth) acrylates, chlorinated polyolefins, rubber, chlorinated rubber, polyurethanes, siloxanes, silanes, polyesters, epoxy resins, polycarbodiimides, phenolic resins and combinations thereof.

[0035] Typically, these agents are solvent-based, which means that they are provided in the form of a solvent such as an organic solvent or water. The solvent-based primer composition comprises the base polymer mixed with a solvent. The solvent can be a single solvent or a blend of solvents. The solvent-based primer composition typically comprises about 5 parts to about 60 parts of a base polymer by weight, more typically about 10 parts to about 40 parts of a base polymer, or even about 10 parts to about 30 parts of a base polymer, wherein the remainder of the primer composition is a solvent and optional additives.

[0036] Particularly suitable film-forming resins include acrylic resins, polyethylene resins, and mixtures thereof. Various acrylic resins are known. Typically, acrylic resins are prepared from various (meth) acrylate monomers, such as polymethyl methacrylate (PMMA), methyl methacrylate (MMA), ethyl acrylate (EA), butyl acrylate (BA), butyl methacrylate (BMA), n-butyl methacrylate (n-BMA), isobutyl methacrylate (IBMA), polyethyl methacrylate, etc., alone or in combination with one another. Exemplary acrylic resins include those commercially available from Rohm and Haas, Co., Philadelphia, Pa., Pennsylvania, under the trade name "PARALOID" and from Ineos Acrylics, Cordova, Tenn., Tenn., under the trade name "ELVACITE" resin. Other suitable polyacrylic materials include those available from SC Johnson, Racine, Wis., under the trade designation "JONCRYL" acrylic resins. Polyvinyl resins include vinyl chloride / vinyl acetate copolymers, such as those available from Rohm and Haas, Co., Philadelphia, Pa., under the trade designation "ACRYLOID" and from Union Carbide Corp., a subsidiary of The Dow Chemical Company ("Dow"), Midland Mich., under the trade designation "VYHH," and vinyl chloride / vinyl acetate / vinyl alcohol terpolymers are also commercially available from Union Carbide Corp. under the trade designation "UCAR VAGH." Other polyvinyl chloride resins were obtained from Occidental Chemical, Los Angeles, Calif.; BF Goodrich Performance Materials, Cleveland, Ohio; and BASF, Mount Olive, NJ.

[0037] Suitable water-based primers are generally emulsions or dispersions that are substantially free of a water-soluble base polymer as a major component. Water-based emulsions and dispersions are useful for reducing solvent emissions by employing primer compositions that are substantially free of volatile organic solvents. Exemplary water-based primers include crosslinked poly(meth)acrylate polymers, such as butyl acrylate / methyl methacrylate copolymers crosslinked with sulfo-carbamate-silanol polymers.

[0038] In some embodiments, the coating comprises a poly(meth)acrylate-based polymer, a urethane-based polymer, a siloxane-based polymer, or a combination thereof.

[0039] Exemplary urethane-based polymers include polyurethane NEO-REZ available from DSM.

[0040] Exemplary siloxanes include those described in U.S. Pat. No. 5,866,222 (Seth et al.) and pending U.S. Patent Application Serial No. 61 / 579115, filed on December 22, 2011, entitled "Adhesive Article Including Primer Layer and Method of Making the Same". U.S. Pat. No. 5,866,222 describes modifying a release coating using 1 wt % to 30 wt % of an MQ tackifying resin to obtain a non-sticky coating having a higher release value for, for example, a block copolymer-based pressure sensitive adhesive. A higher release value means that the pressure sensitive adhesive has a higher adhesion to the coating than to a non-modified release coating. Pending U.S. Patent Application Serial No. 61 / 579115 describes adhesive articles comprising a silicone adhesive and a substrate, wherein a primer layer is interposed between the silicone adhesive and the substrate. The primer layer comprises a silicone polyoxamide.

[0041] Many (meth)acrylate based primers are suitable. In addition to the primers described above, a particularly suitable primer is the commercially available solvent-borne material "3M Adhesion Promoter 2262AT" available from 3M Company, St. Paul, MN.

[0042] Particularly suitable adhesion promoters include Universal Primer 94 from 3M Company and the (meth)acrylate based primer prepared in the Examples section and described as APA-2.

[0043] In some embodiments, the adhesive article also includes a substrate in contact with the second major surface of the optically transparent adhesive layer. Various substrates are suitable. The example of a suitable substrate includes a release liner, a tape backing, and an optical film. The release liner is as described above. The substrate can be a release liner identical to the release liner on which the adhesive article is provided, or it can be different.

[0044] A wide variety of tape backings are suitable. Tape backings are well known in the adhesive art and may include materials such as polymeric films, particularly films of polyolefins, polyesters, polyurethanes, and the like. Other conventional tape backings include webs, such as woven and nonwoven webs, fabrics, foams, and the like. Since adhesive articles are typically optically clear, typically the tape backing is also optically clear and is selected to have this property.

[0045] A variety of optical films are suitable. In some embodiments, the optical film comprises a single layer optical film. In other embodiments, the optical film comprises a multilayer optical film.

[0046] As used herein, the term "optical film" refers to a film that can be used to produce an optical effect. An optical film is typically a polymer-containing film that can be a single layer or multiple layers. The optical film is flexible and can have any suitable thickness. These optical films are typically at least partially transmissive, reflective, anti-reflective, polarized, optically transparent or diffuse with respect to some wavelengths of the electromagnetic spectrum (e.g., wavelengths in the visible, ultraviolet or infrared regions of the electromagnetic spectrum). Exemplary optical films include, but are not limited to: visible mirror films, colored mirror films, solar reflective films, collimating films, ultraviolet reflective films, brightness enhancement films, reflective polarizing films (such as dual brightness enhancement films), absorptive polarizing films, optically transparent films, colored films, and anti-reflective films.

[0047] Some optical films have multiple layers, such as multiple layers containing polymeric materials (e.g., polymers with or without dyes), or multiple layers containing metal materials and polymeric materials. Some optical films have alternating layers of polymeric materials with different refractive indices. Other optical films have alternating polymeric layers and metal-containing layers. Exemplary optical films are described in the following patents: U.S. Pat. No. 6,049,419 (Wheatley et al.); U.S. Pat. No. 5,223,465 (Wheatley et al.); U.S. Pat. No. 5,882,774 (Jonza et al.); U.S. Pat. No. 6,049,419 (Wheatley et al.); U.S. Pat. No. RE 34,605 ​​(Schrenk et al.); U.S. Pat. No. 5,579,162 (Bjornard et al.); and U.S. Pat. No. 5,360,659 (Arends et al.).

[0048] Adhesive article of the present disclosure can have various thicknesses.Because the thickness of tackifier layer is very thin relative to optically clear adhesive layer, the total thickness of adhesive article is substantially the same as the thickness of optically clear adhesive layer.In some embodiments, optically clear adhesive layer has a thickness of 1 micron to 1 millimeter.In some embodiments, optically clear adhesive layer has a thickness of at least 25 microns (1 mil), at least 51 microns (2 mils) or even at least 102 microns (4 mils).In some embodiments, optically clear adhesive layer has a thickness less than 0.9 millimeter, 0.75 millimeter or even less than 0.5 millimeter.

[0049] Adhesive articles of the present disclosure have various desired characteristics. As mentioned above, adhesive articles are optically transparent normally. Also as mentioned above, the presence of the adhesion promoting layer provides the adhesion increased by the adhesive layer. As will be discussed in more detail below, the tackifier layer can be prepared in two different ways. In many embodiments, the adhesion promoting layer is prepared in the following manner: the adhesion promoting material is arranged on the second major surface of the release liner in the form of a solution, emulsion or dispersion and is dried to remove the solvent. In other embodiments, the adhesion promoting layer is prepared in the following manner: the adhesion promoting material is arranged on the first major surface of the optically transparent adhesive layer in the form of a solution, emulsion or dispersion and is dried to remove the solvent.

[0050] As the name implies, the adhesion promoting layer increases the adhesion of the optically clear adhesive layer to the substrate surface such that when the adhesion promoting layer surface contacts the substrate surface, the adhesion is greater than the adhesion of the same article without the adhesion promoting layer.

[0051] Examples of articles of manufacture disclosed herein are shown in Figure 1 In the embodiment, the article 100 includes a first release liner 110, a primer layer 120 disposed between the first release liner 110 and an adhesive layer 130. An optional second release liner 140 is disposed on the adhesive layer 130.

[0052] Also disclosed herein is a method for preparing an adhesive article, wherein the adhesive article is self-priming. Two different methods are disclosed. In the first method, an adhesion promoting material is applied to the surface of a release liner, the adhesive layer is contacted with the adhesion promoting material, and when removed from the liner, the adhesion promoting material adheres to the adhesive layer. In the second method, an adhesion promoting material is applied to the adhesive surface of the adhesive layer, and then the adhesive layer is contacted with the surface of the release liner.

[0053] In some embodiments, a first method for preparing an adhesive article includes: providing a release liner having a first major surface and a second major surface, wherein at least the second major surface includes a release surface; providing an adhesion promoting composition; disposing the adhesion promoting composition on the second major surface of the release liner to form an adhesion promoting layer on the second major surface of the release liner. The adhesion promoting layer has a first major surface and a second major surface, and the first major surface is in contact with the release surface of the release liner. The method also includes: providing an optically clear adhesive or a precursor mixture capable of forming an optically clear adhesive; disposing the optically clear adhesive or the precursor mixture on the second major surface of the adhesion promoting layer to form an optically clear pressure-sensitive adhesive layer. The optically clear adhesive layer can be a pressure-sensitive adhesive layer or a heat-activated adhesive layer, and has a first major surface and a second major surface, wherein the first major surface of the optically clear adhesive layer is in contact with the second major surface of the adhesion promoting layer. The adhesion between the optically clear adhesive layer and the adhesion promoting layer is higher than the adhesion between the adhesion promoting layer and the release liner, so that when the optically clear adhesive layer is removed from the release liner, the adhesion promoting layer remains adhered to the surface of the optically clear adhesive layer.

[0054] In some embodiments, disposing the adhesion promoting composition on the second major surface of the release liner comprises: applying a solution, emulsion or dispersion of the adhesion promoting material; and drying the coating. Suitable adhesion promoting materials are described above and include polyamides, poly(meth)acrylates, chlorinated polyolefins, rubber, chlorinated rubber, polyurethanes, siloxanes, silanes, polyesters, epoxies, polycarbodiimides, phenolic resins, and combinations thereof.

[0055] The optically clear adhesive layer is a pressure sensitive adhesive or a heat activated adhesive. The adhesive is as described above and is selected from (meth)acrylate pressure sensitive adhesives, (meth)acrylate-based pressure sensitive adhesives, polyolefin pressure sensitive adhesives, polyurethane pressure sensitive adhesives, silicone-based pressure sensitive adhesives, polyvinyl butyral heat activated adhesives, or combinations thereof.

[0056] Examples of adhesive precursor mixtures that can be applied to the adhesion promoting layer to form an optically clear pressure sensitive adhesive layer include a coatable (meth)acrylate based syrup and a precursor mixture of a photoinitiator. After the coatable (meth)acrylate syrup is disposed on the adhesion promoting layer present on the second surface of the release liner, the precursor mixture is irradiated to cure the precursor mixture and form an adhesive layer. This method of preparing a monomer mixture, partially prepolymerizing the monomer mixture to form a coatable syrup is described, for example, in U.S. Pat. No. 6,339,111 (Moon et al.).

[0057] In some embodiments, the method may further include disposing a substrate on the second major surface of the optically clear pressure sensitive adhesive layer. Suitable substrates are described above, and may include a release liner, a tape backing, or an optical film.

[0058] The formed adhesive article has an optically clear adhesive layer having a thickness of 1 micrometer to 1 millimeter. The adhesive article has the above-mentioned desirable adhesion properties. Among these properties are the following: the increased adhesion of the article having the adhesion promoting layer to the substrate surface is greater than the same adhesive article without the adhesion promoting layer.

[0059] In some embodiments, a second method for preparing an adhesive article includes providing a release liner having a first major surface and a second major surface, wherein at least the second major surface includes a release surface. The method also includes: providing an adhesion promoting composition; providing an optically clear adhesive layer having a first major surface and a second major surface; disposing the adhesion promoting composition on the first major surface of the optically clear adhesive layer to form an adhesion promoting layer on the first major surface of the optically clear adhesive layer, wherein the adhesion promoting layer has a second major surface in contact with the first major surface of the optically clear adhesive layer and an exposed first major surface. The optically clear adhesive layer having the adhesion promoting layer on the surface contacts the release surface of the release liner so that the first major surface of the adhesion promoting layer contacts the release surface of the release liner. The adhesion between the optically clear adhesive layer and the adhesion promoting layer is higher than the adhesion between the adhesion promoting layer and the release liner, so that when the optically clear adhesive layer is removed from the release liner, the adhesion promoting layer remains adhered to the surface of the optically clear adhesive layer. The elements of the adhesive article are as described above.

[0060] Example

[0061] These examples are for illustrative purposes only and are not intended to limit the scope of the appended claims. The following abbreviations are used: cm = centimeter; N = Newton. The terms "weight %", "% by weight" and "wt %" are used interchangeably.

[0062] These examples are provided for illustrative purposes only and are not intended to limit the scope of the appended claims.

[0063] Abbreviations

[0064]

[0065] Test Method

[0066] 180° peel adhesion

[0067] The peel adhesion test is similar to the test method described in ASTM D 3330-90, but a glass substrate is substituted for the stainless steel substrate described in that test.

[0068] Adhesive samples were laminated to 51 micron thick (2 mil) polyethylene terephthalate films and cut into 1.0 cm x 15 cm strips. Each strip was then adhered to a 10 cm x 20 cm clean glass coupon washed with solvent using a 2 kg roller rolled over the strips once. The bonded assemblies were left at room temperature for about 20 minutes or 3 days and tested for 180° peel adhesion at a rate of 15 cm / min (6 in / min) within a five second data collection period using an IMASS Slip / Peel Tester (3M90, commercially available from Instruments Inc., Strongsville, OH). Two samples were tested; the peel adhesion values ​​recorded are the average of the peel adhesion values ​​for each of the two samples.

[0069] Example

[0070] Synthesis Example Example 1: Preparation of Adhesion Promoter-2

[0071] The acrylate polymer for APA-2 was prepared by mixing 53.2 grams of isooctyl acrylate, 53.2 grams of methyl methacrylate (Dow Chemical), 20.3 grams of acrylic acid (Dow Chemical), and 126.6 grams of ethyl acetate. 1.0 grams of thermal initiator (VAZO-67 from Chemours) was added, and the solution was deoxygenated with nitrogen for 2 minutes. After heating at 65°C for 47 hours, a solution was obtained that was determined to have a solids content of 50.9% and an IV of 0.74. The polymer concentrate was then diluted with additional ethyl acetate to a 5.0% solids primer coating solution.

[0072] Example E1 and Comparative Examples CE1-CE2

[0073] Samples of Adhesive-1 were prepared. CE1 and CE2 were prepared by coating the adhesive on release liner-1. For Example E1, APA-1 was coated on release liner-1, and then Adhesive-1 was coated on the APA-1 coating. On all samples, Release Liner-2 was coated on the exposed surface of Adhesive-1.

[0074] The samples were tested for peel adhesion to glass substrates. For sample CE-1, Adhesive-1 was used, and for sample CE-2, Adhesive-1 was used and the glass substrate was treated with APA. The data are shown in Table 1.

[0075] Table 1

[0076]

[0077] Example E2 and Comparative Example CE3

[0078] Samples of Adhesive-2 were prepared. CE3 was prepared by coating the adhesive on release liner-1. For Example E2, APA-2 was coated on release liner-1 and then Adhesive-1 was coated on the APA-2 coating. On all samples, release liner-2 was coated on the exposed surface of Adhesive-2.

[0079] The samples were tested for peel adhesion to a glass substrate. For sample CE-3, Adhesive-2 was used. The data is shown in Table 2.

[0080] Table 2

[0081]

Claims

1. An adhesive product, comprising: a release liner having a first major surface and a second major surface, wherein at least the second major surface comprises a release surface; an adhesion promoting layer having a first major surface and a second major surface, wherein the first major surface of the adhesion promoting layer is in contact with the second major surface of the release liner; and An optically clear adhesive layer having a first major surface and a second major surface, wherein the first major surface of the optically clear adhesive layer is in contact with the second major surface of the adhesion-promoting layer, wherein the adhesion between the optically clear adhesive layer and the adhesion-promoting layer is higher than the adhesion between the adhesion-promoting layer and the release liner, so that when the optically clear adhesive layer is removed from the release liner, the adhesion-promoting layer remains adhered to the surface of the optically clear adhesive layer, and wherein the adhesion-promoting layer is optically clear.

2. The adhesive article of claim 1, wherein the optically clear adhesive comprises a (meth)acrylate pressure sensitive adhesive, a (meth)acrylate-based pressure sensitive adhesive, a polyolefin pressure sensitive adhesive, a polyurethane pressure sensitive adhesive, a silicone-based pressure sensitive adhesive, a polyvinyl butyral heat-activated adhesive, or a combination thereof.

3. The adhesive article of claim 1, wherein the adhesion promoting layer comprises polyamides, poly(meth)acrylates, chlorinated polyolefins, rubber, chlorinated rubber, polyurethanes, siloxanes, silanes, polyesters, epoxies, polycarbodiimides, phenolic resins, and combinations thereof.

4. The adhesive article of claim 3, wherein the adhesion promoting layer comprises a (meth)acrylate based primer.

5. The adhesive article of claim 1, wherein the adhesive article further comprises a substrate in contact with the second major surface of the optically clear pressure sensitive adhesive layer.

6. The adhesive article of claim 5, wherein the substrate comprises a release liner, a tape backing, or an optical film. 7 . The adhesive article of claim 1 , wherein the optically clear adhesive layer has a thickness of 1 micrometer to 1 millimeter.

8. The adhesive article of claim 1, wherein the adhesion promoting layer is prepared by disposing an adhesion promoting material in the form of a solution, emulsion or dispersion on the second major surface of the release liner and drying to remove the solvent.

9. The adhesive article of claim 1, wherein the adhesion promoting layer is prepared by disposing an adhesion promoting material in the form of a solution, emulsion or dispersion on the first major surface of the optically clear adhesive layer and drying to remove the solvent.

10. The adhesive article of claim 1, wherein when the adhesion promoting layer surface is in contact with a substrate surface, the adhesive article has an adhesion that is greater than the adhesion of the same article without the adhesion promoting layer.

11. A method for preparing an adhesive product, the method comprising: providing a release liner, wherein the release liner has a first major surface and a second major surface, and wherein at least the second major surface comprises a release surface; providing an adhesion promoting composition; disposing the adhesion promoting composition on the second major surface of the release liner to form an adhesion promoting layer on the second major surface of the release liner, wherein the adhesion promoting layer has a first major surface and a second major surface, the first major surface of the adhesion promoting layer being in contact with the release surface of the release liner; Providing an optically clear adhesive or a precursor mixture capable of forming an optically clear adhesive; The optically clear adhesive or precursor mixture is disposed on the second major surface of the adhesion-promoting layer to form an optically clear adhesive layer, the optically clear adhesive layer having a first major surface and a second major surface, wherein the first major surface of the optically clear adhesive layer is in contact with the second major surface of the adhesion-promoting layer, wherein the adhesion between the optically clear adhesive layer and the adhesion-promoting layer is higher than the adhesion between the adhesion-promoting layer and the release liner, so that when the optically clear adhesive layer is removed from the release liner, the adhesion-promoting layer remains adhered to the surface of the optically clear adhesive layer.

12. The method of claim 11, wherein disposing the adhesion promoting composition on the second major surface of the release liner comprises: applying a solution, emulsion or dispersion of an adhesion promoting material; and dry coating.

13. The method of claim 12, wherein the adhesion promoting material comprises polyamide, poly(meth)acrylate, chlorinated polyolefin, rubber, chlorinated rubber, polyurethane, siloxane, silane, polyester, epoxy resin, polycarbodiimide, phenolic resin, and combinations thereof.

14. The method of claim 11, wherein the optically clear adhesive or precursor mixture comprises an optically clear adhesive comprising a (meth)acrylate pressure sensitive adhesive, a (meth)acrylate-based pressure sensitive adhesive, a polyolefin pressure sensitive adhesive, a polyurethane pressure sensitive adhesive, a silicone-based pressure sensitive adhesive, a polyvinyl butyral heat-activated adhesive, or a combination thereof.

15. The method of claim 11, wherein the optically clear pressure-sensitive adhesive or precursor mixture comprises a precursor mixture of a coatable (meth)acrylate-based syrup and a photoinitiator, and after the coatable (meth)acrylate syrup is disposed on the second surface of the release liner, the precursor mixture is irradiated and cured.

16. The method of claim 11, further comprising disposing a substrate on the second major surface of the optically clear pressure sensitive adhesive layer.

17. The method of claim 16, wherein the substrate comprises a release liner, a tape backing, or an optical film.

18. The method of claim 11, wherein the optically clear adhesive layer has a thickness of 1 micrometer to 1 millimeter.

19. The method of claim 11, further comprising removing the optically clear pressure-sensitive adhesive layer, wherein at least a portion of the adhesion promoting layer disposed on a surface of the optically clear pressure-sensitive adhesive layer is removed from the release liner and contacts a surface of a substrate such that the adhesion of the adhesive article is greater than the adhesion of the same article without the adhesion promoting layer.

20. A method of preparing an adhesive article, the method comprising: providing a release liner, wherein the release liner has a first major surface and a second major surface, and wherein at least the second major surface comprises a release surface; providing an adhesion promoting composition; providing an optically clear adhesive layer having a first major surface and a second major surface; disposing the adhesion promoting composition on the first major surface of the optically clear adhesive layer to form an adhesion promoting layer on the first major surface of the optically clear adhesive layer, wherein the adhesion promoting layer has a second major surface in contact with the first major surface of the optically clear adhesive layer and an exposed first major surface; The optically clear adhesive layer having the adhesion promoting layer is disposed on the release surface of the release liner such that a first major surface of the adhesion promoting layer is in contact with the release surface of the release liner, wherein the adhesion force between the optically clear adhesive layer and the adhesion promoting layer is higher than the adhesion force between the adhesion promoting layer and the release liner, so that when the optically clear adhesive layer is removed from the release liner, the adhesion promoting layer remains adhered to the surface of the optically clear adhesive layer.

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