Siloxane-based optically clear adhesives with Anti-corrosion properties

Abstract

Siloxane-based corrosion resistant adhesives are prepared from a reaction mixture such that upon curing in the form of a layer, the siloxane-based adhesive formed has a stable modulus as measured by DMA (Dynamic Mechanical Analysis) and a shear storage modulus at a frequency of 1 Hz that does not exceed 0.2 MPa. Additionally, the cured siloxane-based adhesive layer is optically clear and upon lamination to a silver nanowire film, the resistance of the silver nanowire film changes by less than 10% after aging for 500 hours at 65°C / 90% relative humidity. The reaction mixture to form the siloxane-based adhesive includes at least one vinyl-functional siloxane, at least one hydrido- functional siloxane, at least one hydrosilylation catalyst, at least one siloxane tackifying resin, and at least one corrosion prevention agent.

Description

[0001]SILOXANE-BASED OPTICALLY CLEAR ADHESIVES WITH ANTI- CORROSION PROPERTIES Summary Disclosed herein are corrosion resistant adhesive compositions, laminate articles prepared with these corrosion resistant adhesive compositions, and methods of preparing these laminate articles. In some embodiments the corrosion resistant adhesive composition comprises a siloxane-based adhesive prepared from a reaction mixture such that upon curing in the form of a layer, the siloxane-based adhesive has a stable modulus as measured by DMA (Dynamic Mechanical Analysis) within a temperature range of between about -30°C to 70°C and the cured adhesive layer has a shear storage modulus at a frequency of 1 Hz that does not exceed 0.2 MPa. Additionally, the cured siloxane-based adhesive layer is optically clear and upon lamination of the cured siloxane-based adhesive layer to a silver nanowire film, the resistance of the silver nanowire film changes by less than 10% after aging for 500 hours at 65°C / 90% relative humidity. The reaction mixture to form the siloxane-based adhesive comprises at least one vinyl-functional siloxane, at least one hydrido-functional siloxane, at least one hydrosilylation catalyst, at least one siloxane tackifying resin, and at least one corrosion prevention agent. Also disclosed herein are laminate articles. In some embodiments, the laminate article comprises a first substrate with a first major surface and a second major surface, an adhesive layer disposed on at least a portion of the second major surface of the first substrate, and a second substrate with first major surface and a second major surface, where the first major surface of the second substrate is disposed on the adhesive layer. The adhesive layer comprises a layer of the cured siloxane-based adhesive described above. Also disclosed are methods of preparing laminate articles. In some embodiments, the method of preparing a laminate article comprises providing a first substrate with a first major surface and a second major surface, providing a reaction mixture for preparing a siloxane-based adhesive or providing a siloxane-based adhesive layer, disposing the reaction mixture or the siloxane-based adhesive layer on at least a portion of the second major surface of the first substrate, curing the reaction mixture to form a siloxane-based adhesive layer if a reaction mixture is used, providing a second substrate with a first major surface and a second major surface, and disposing the first major surface of the second substrate on the siloxane-based adhesive layer. If a reaction mixture is used, the reaction comprises at least one vinyl-functional siloxane, at least one hydrido-functional siloxane, at least one hydrosilylation catalyst, at least one siloxane tackifying resin, and at least one corrosion prevention agent. If a siloxane-based adhesive layer is used it is a cured layer of the reaction mixture. Brief Description of the Drawings The present application may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying drawings. Figure 1 is a cross sectional view of an article of the current disclosure. Detailed Description A wide range of optical articles have multiple layers. The multiple layers often are adhered to each other with adhesive layers. These adhesive layers have a wide range of desired or required properties. Achieving some properties is very complex process. Adhesive layers are designed to adhere together two films or substrates, but additional properties are also generally required of the adhesive layers. Many of these properties are difficult to achieve since imparting a new property to the adhesive layer must be achieved without sacrificing adhesive properties. A range of optically clear adhesive properties have been developed for use in optical articles. These adhesives have adhesive properties and also are optically clear. This combination of properties makes them very desirable for a wide range of uses. In some uses, it is desirable for the optically clear adhesive to have additional properties. However, these new properties cannot be achieved by sacrificing the adhesive or optical properties. Among the articles that require optically clear adhesives are foldable articles. Examples include flexible OLED displays in foldable phones, tablets and notebooks. Additionally, the trend in such devices is towards reduced thicknesses with a small folding radius. This brings about numerous design constraints for the materials of the display. For example, thin adhesive layers are expected to reduce the stress generated during display folding while still providing high adhesion to the various substrates of the display. Additionally, the OLED display needs to function over a wide temperature range without cracking or creating temporary distortions from material creep as the device is folded, rolled, bent, or flexed. However, it is often observed that peel adhesion is typically reduced by materials with these properties. Weaker peel adhesion may further increase the risk of delamination during dynamic folding. Thus, providing an adhesive film that is useful for the mechanical deformations associated with folding along with sufficient adhesion to the appropriate device substrates is crucial for overall device performance. Among the pressure sensitive adhesives developed for optical uses are siloxane- based pressure sensitive adhesives, often referred to as “silicone PSAs”. However, these siloxane-based pressure sensitive adhesives often have issues when laminated to nanowire layers. Typically, the siloxane-based pressure sensitive adhesives are incompatible with the nanowire layers and upon aging cause an increase in the resistance of the nanowire layers. Often the nanowire layers are metal nanowire films. Metal nanowire films are films on which metal nanowires are deposited. As the name implies, nanowires are wires that have diameters in the nanometer range, typically 10-200 nanometers. These films are often less than 100 micrometers thick and are frequently used in flexible electronics due to their combination of high conductivity, ability to bend to narrow radii with limited change in conductivity, and high optical transparency. Nanowire films are useful for applications such as capacitive touch sensors, chemical sensors, optical sensors, and antennae, in which they may also be optically clear. A variety of metals can be used to prepare nanowire films. Typically, the metals are highly conductive metals such as copper and silver. Silver nanowire films are typically used in many applications. There is a need for adhesive films that have a desirable balance of peel adhesion, low haze, low Tg, low modulus, and are compatible with nanowire layers. In this disclosure, corrosion-resistant adhesive films are described that contain a siloxane-based polymeric matrix prepared from the catalyzed reaction of a vinyl-functional siloxane and a hydroxyl-functional siloxane, a siloxane tackifying resin, and a corrosion prevention agent. These adhesive and have this desirable balance of properties. The term “adhesive” as used herein refers to polymeric compositions useful to adhere together two adherends. Examples of adhesives are pressure sensitive adhesives. Pressure sensitive adhesive compositions are well known to those of ordinary skill in the art to possess properties including the following: (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 cleanly removable from the adherend. Materials that have been found to function well as pressure sensitive adhesives are polymers designed and formulated to exhibit the requisite viscoelastic properties resulting in a desired balance of tack, peel adhesion, and shear holding power. Obtaining the proper balance of properties is not a simple process. The term “OCA” as used herein refers to optically clear adhesives. Many popular pressure sensitive adhesives that are widely used are based on (meth)acrylates. The term “(meth)acrylate” refers to monomeric acrylic or methacrylic esters of alcohols. Acrylate and methacrylate monomers or oligomers are referred to collectively herein as "(meth)acrylates”. Materials referred to as “(meth)acrylate functional” are materials that contain one or more (meth)acrylate groups. Although pressure sensitive adhesives, particularly, optically clear adhesives, based on siloxane chemistry (Silicone OCA or SiOCA) are less common, but siloxane OCAs do present a class of materials with unique properties such as a relatively low refractive indices and stability upon environmental aging. The terms “siloxane” and “siloxane-based” as used herein refer to polymers or units of polymers that contain siloxane units. The terms silicone or siloxane are used interchangeably and refer to units with dialkyl or diaryl siloxane (-SiR2O-) repeating units. The terms "room temperature" and "ambient temperature" are used interchangeably to mean temperatures in the range of 20°C to 25°C. The terms “Tg” and “glass transition temperature” are used interchangeably. If measured, Tg values are determined by Differential Scanning Calorimetry (DSC) at a scan rate of 10°C / minute, unless otherwise indicated. Typically, Tg values for copolymers are not measured but are calculated using the well-known Fox Equation, using the monomer Tg values provided by the monomer supplier, as is understood by one of skill in the art. The term “adjacent” as used herein when referring to two layers means that the two layers are in proximity with one another with no intervening open space between them. They may be in direct contact with one another (e.g. laminated together) or there may be intervening layers. The terms “polymer” and “macromolecule” are used herein consistent with their common usage in chemistry. Polymers and macromolecules are composed of many repeated 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 resultant material formed from a polymerization reaction. The term “alkyl” refers to a monovalent group that is a radical of an alkane, which is a saturated hydrocarbon. The alkyl can be linear, branched, cyclic, or combinations 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. The term “aryl” refers to a monovalent group that is aromatic and carbocyclic. The aryl can have one to five rings that are connected to or fused to the aromatic ring. The other ring structures can be aromatic, non-aromatic, or combinations thereof. Examples of aryl groups include, but are not limited to, phenyl, biphenyl, terphenyl, anthryl, naphthyl, acenaphthyl, anthraquinonyl, phenanthryl, anthracenyl, pyrenyl, perylenyl, and fluorenyl. Unless otherwise indicated, the terms “optically transparent”, and “visible light transmissive” are used interchangeably, and refer to an article, film or adhesive that has a high light transmittance over at least a portion of the visible light spectrum (about 400 to about 700 nm). Typically, optically transparent articles have a visible light transmittance of at least 90% and a haze of less than 10%. Unless otherwise indicated, "optically clear" refers to an adhesive or article that has a high light transmittance over at least a portion of the visible light spectrum (about 400 to about 700 nm), and that exhibits low haze, typically less than about 5%, or even less than about 2%. In some embodiments, optically clear articles exhibit a haze of less than 1% at a thickness of 50 micrometers or even 0.5% at a thickness of 50 micrometers. Typically, optically clear articles have a visible light transmittance of at least 95%, often higher such as 97%, 98% or even 99% or higher. As used herein, the terms “flexible” and “rigid” are used according to their commonly understood meanings. Substrates that are flexible are capable of bending without cracking or breaking, and substrates that are rigid are not capable of bending without cracking or breaking. Typically, flexible substrates are those that are capable of bending from an angle of 0° to an angle of at least 45°, or even 90° or greater, and then be bent back to an angle of 0° without being damaged by breaking or cracking. Disclosed herein are corrosion resistant adhesive compositions that are siloxane- based. The corrosion resistant adhesive compositions are cured to form a corrosion resistant adhesive. Typically, the corrosion resistant adhesives are pressure sensitive adhesives. In some embodiments, the corrosion resistant adhesive composition that upon curing forms a corrosion resistant adhesive, comprises a reaction mixture comprising at least one vinyl-functional siloxane, at least one hydrido-functional siloxane, at least one hydrosilylation catalyst, at least one siloxane tackifying resin, and at least one corrosion prevention agent. Each of these components is described in detail below. Upon curing in the form of a layer, the siloxane-based adhesive has a stable modulus as measured by DMA (Dynamic Mechanical Analysis) within a temperature range of between about -30°C to 70°C, and the cured adhesive layer has a shear storage modulus at a frequency of 1 Hz that does not exceed 0.2 MPa. Upon lamination of the cured siloxane-based adhesive layer is optically clear and corrosion resistant. By corrosion resistant, it is meant that upon lamination of the cured siloxane-based adhesive layer to a silver nanowire film, the resistance of the silver nanowire film changes by less than 10% after aging for 500 hours at 65°C / 90% relative humidity. The reaction mixture that forms the corrosion resistant adhesive comprises at least one vinyl-functional siloxane. A wide range of vinyl-functional siloxanes are suitable. In some embodiments, the at least one vinyl-functional siloxane is described by Formula 1: Formula 1 where each R1, R2, R3, and R4 are independently selected from the group consisting of an alkyl group, an aryl group and an ethylenically unsaturated group; each R5 is an alkyl group; each X is an ethylenically unsaturated group or an alkyl group; and n and m are integers, and at least one of m or n is not zero. If the X groups are not ethylenically unsaturated groups, at least one of R1 and R3 are ethylenically unsaturated groups. Vinyl-functional siloxanes of Formula I where the X groups are ethylenically unsaturated are called “terminal-functional” and those wherein the X groups are not ethylenically unsaturated and at least one of R1 and R3 are ethylenically unsaturated are called “pendant-functional”. It is also possible to have vinyl-functional siloxanes of Formula I where the X groups are ethylenically unsaturated and at least one of R1 and R3 are ethylenically unsaturated. In some embodiments, the vinyl-functional siloxanes of the reaction mixture that forms the corrosion resistant pressure sensitive adhesive is a pendant-functional vinyl- functional siloxane. It may be desirable to have only one of the groups R1 and R3 be ethylenically unsaturated. In some particularly suitable embodiments, the at least one vinyl-functional siloxane is described by Formula 1A: Formula 1A wherein each R1, R2, R3, and R4 are independently selected from the group consisting of an alkyl group or an aryl group; each R5 is an alkyl group; each X is an ethylenically unsaturated group; and n and m are integers, and at least m is not zero. A wide array of vinyl-functional siloxanes are commercially available. A particularly suitable one is DEHESIVE 948 available from Wacker. The reaction mixture that forms the corrosion resistant adhesive comprises at least one hydrido-functional siloxane. A wide range of hydrido-functional siloxanes are suitable. In some embodiments, the at least one hydrido-functional siloxane is described by Formula 2: R5 R1 R3 R5 R5Si O Si OmSi OnSiR5 where R1, R2, R3, and R4 are independently selected from the group consisting of an alkyl group, an aryl group and a hydrido group; each R5 is an alkyl group; and n and m are integers, and at least one of m or n is not zero. In some particularly suitable embodiments, the at least one hydrido-functional siloxane is described by Formula 2A: R5 R1 R3 R5 where R1 is a hydrido group, R2, R3, and R4 are independently selected from the group consisting of an alkyl group or an aryl group; each R5 is an alkyl group; and n and m are integers, and at least m is not zero. A wide array of hydrido-functional siloxanes are commercially available. A particularly suitable one is HMS-151 available from Gelest Inc., Morrisville, PA. The reaction mixture that forms the corrosion resistant adhesive comprises at least one hydrosilylation catalyst. The catalyst facilitates the hydrosilylation reaction, that is to say the reaction between vinyl-functional siloxanes and hydrido-functional siloxanes. A wide range of catalysts are suitable, but platinum-based (Pt-based) catalysts are particularly suitable. The Pt based catalyst catalyzes the reaction between the vinyl groups on the vinyl-functional siloxane and the hydride groups on the hydrido-functional siloxane. An example of a commercially available Pt catalyst includes, but is not limited to, SIP 6831.2, a platinum divinyltetramethyldisiloxane complex in xylene, available from Gelest. Typical Pt catalyst levels are between about 50 and about 150 ppm Pt. The reaction mixture that forms the corrosion resistant adhesive comprises at least one siloxane tackifying resin. The siloxane tackifying resin is added to the reaction mixture. A wide range of tackifying resins are suitable. Particularly suitable are MQ resins. Useful MQ tackifying resins include, for example, MQ silicone resins, MQD silicone resins, and MQT silicone resins. These tackifying resins often have a number average molecular weight of about 100 to about 50,000, or about 500 to about 20,000 and generally have methyl substituents. The MQ silicone resins include both non-functional and functional resins, the functional resins having one or more functionalities including, for example, silicon-bonded hydrogen, silicon-bonded alkenyl, and silanol. MQ silicone resins are copolymeric silicone resins having R'3SiO1 / 2units (M units) and SiO4 / 2 units (Q units). Such resins are described in, for example, Encyclopedia of Polymer Science and Engineering, vol. 15, John Wiley & Sons, New York, (1989), pp. 265 to 270, and U.S. Patent Nos. 2,676,182 (Daudt at al.); 3,627,851 (Brady); 3,772,247 (Flannigan); and 5,248,739 (Schmidt et al.). MQ silicone resins having functional groups are described in U.S. Patent No. 4,774,310 (Butler), which describes silyl hydride groups, U.S. Patent No. 5,262,558 (Kobayashi et al.), which describes vinyl and trifluoropropyl groups, and U.S. Patent No.4,707,531 (Shirahata), which describes silyl hydride and vinyl groups. The above-described resins are generally prepared in solvent. Dried or solventless MQ silicone resins are prepared as described in U.S. Patent Nos. 5,319,040 (Wengrovius et al.); 5,302,685 (Tsumura); and 4,935,484 (Wolfgruber). MQD silicone resins are terpolymers having R'3SiO1 / 2units (M units), SiO4 / 2units (Q units), and R'2SiO2 / 2 units (D units) as described, e.g., in U.S. Patent No. 5,110,890 (Butler). MQT silicone resins are terpolymers having R3SiO1 / 2units (M units), SiO4 / 2units (Q units), and RSiO3 / 2units (T units) (MQT resins). The MQ silicone resins are often supplied in an organic solvent. Examples of commercially available suitable MQ resins (also called a tackifier) include 2-7066 supplied by Dow Corning and SR545 supplied by Momentive, available as 60% solutions in toluene. In one embodiment, the MQ silicone resin can also include blends of two or more silicone resins. The reaction mixture that forms the corrosion resistant adhesive comprises at least one corrosion prevention agent. The corrosion prevention agent is typically added to the reaction mixture. A wide range of corrosion prevention agents are useful, including benzothiazole or substituted benzothiazoles, pantoprazole sodium, benzotriazole (BTA), 2- mercaptobenzoimidazole (2-MBI), sodium dodecylbenzenesulfonate (SDBS), SDBS and 2-MBI, 5-Phenyl-2-amino-1,3,4-thiadiazole (APT), 5-(4-methoxyphenyl)-2-amino-1,3,4- thiadiazole (AMPT), 1-(p-Tolyl)-4-methylimidazole, 1-Phenyl-4-methylimidazole, 4- methyl-5-hydroxymethylimidazole, 2-mercapto benzimidazole (MBI) and KI, 5-methyl- 2,4-dihydropyrazol-3-one (MHPO), 5-methyl-2-phenyl-2,4-dihydropyrazol-3-one (MPPO), cyproconazole, 1-phenyl-3-hydroxy-1,2,4-triazole, nitrotetrazolium blue chloride (NTBC), thioles, amino acids, and Schiff bases. In some embodiments, the at least one corrosion prevention agent comprises a benzothiazole or substituted benzothiazole. Besides the above listed components, a variety of optional materials can be included in the reaction mixture. A particularly suitable material is a solvent. The use of a solvent in the reaction mixture can aid in mixing the components to facilitate the reaction. Examples of suitable solvents include hydrocarbon solvents such as alkane-based solvents and aromatic solvents. Suitable alkane-based solvents include hexane, heptane and petroleum ether. Examples of suitable aromatic solvents include toluene and xylene. If used, typically the solvent is removed either simultaneously with the curing of the reaction mixture or before the curing reaction is complete. A wide range of formulations for the reaction mixture are suitable. In some embodiments, the reaction mixture includes the siloxane tackifying resin and the corrosion prevention agent as well as a solvent. Exemplary formulations comprise: 60-70 weight % of at least one vinyl-functional siloxane; 0.5-2 weight % of at least one hydrido-functional siloxane; 0.005-0.012 weight % of at least one hydrosilylation catalyst; 30-38 weight % of at least one siloxane tackifying agent; and 0.1-1.5 weight % of at least one corrosion prevention agent; where weight % refers to the dry weight per 100 parts by weight of the total reaction mixture. The reaction mixture may also comprise at least one solvent. One or more of the components may be supplied dissolved in a solvent and / or additional solvent can be added. As mentioned above the corrosion resistant adhesive compositions of this disclosure have a variety of desirable properties. The components described above are mixed to form a reaction mixture, and this reaction mixture is cured to form a corrosion resistant siloxane-based pressure sensitive adhesive. Upon curing in the form of a layer, the siloxane-based adhesive has a stable modulus as measured by DMA (Dynamic Mechanical Analysis) within a temperature range of between about -30°C to 70°C, and the cured adhesive layer has a shear storage modulus at a frequency of 1 Hz that does not exceed 0.2 MPa. Upon lamination of the cured siloxane-based adhesive layer is optically clear and corrosion resistant. By corrosion resistant, it is meant that upon lamination of the cured siloxane-based adhesive layer to a silver nanowire film, the resistance of the silver nanowire film changes by less than 10% after aging for 500 hours at 65°C / 90% relative humidity. In some embodiments, the cured siloxane-based adhesive layer is even more corrosion resistant, such that upon lamination of the cured siloxane-based adhesive layer to a silver nanowire film the resistance of the silver nanowire film changes by less than 10% after aging for 500 hours at 85°C / 85% relative humidity. Besides these properties, the cured siloxane-based adhesive also has desirable dielectric constant features. In some embodiments, the cured siloxane-based adhesive layer has a dielectric constant of less than or equal to 2.70 when measured at 100 kHz and the dielectric constant is consistent, meaning that the dielectric constant when measured at different frequencies is within 0.1 of the value when measured at 100k Hz. Not only is the dielectric constant consistent, but also the dielectric constant is stable, meaning that the dielectric constant changes less than 0.1 from the original value when the adhesive is aged for 500 hours at 65°C / 90% relative humidity. Also disclosed herein are laminate articles. In some embodiments, the laminate articles comprise a first substrate with a first major surface and a second major surface, an adhesive layer disposed on at least a portion of the second major surface of the first substrate, and a second substrate with first major surface and a second major surface, wherein the first major surface of the second substrate is disposed on the adhesive layer. The adhesive layer is the corrosion-resistant siloxane-based pressure sensitive adhesive described above. The adhesive layer comprises a siloxane-based adhesive prepared from a reaction mixture comprising: at least one vinyl-functional siloxane; at least one hydrido-functional siloxane; at least one hydrosilylation catalyst; at least one siloxane tackifying resin; and at least one corrosion prevention agent. Upon curing of the reaction mixture in the form of a layer, the siloxane-based adhesive has a stable modulus as measured by DMA (Dynamic Mechanical Analysis) within a temperature range of between about -30°C to 70°C, the cured adhesive layer has a shear storage modulus at a frequency of 1 Hz that does not exceed 0.2 MPa, and wherein upon lamination of the cured siloxane-based adhesive layer to a silver nanowire film the resistance of the silver nanowire film changes by less than 10% after aging for 500 hours at 65°C / 90% relative humidity, and wherein the cured siloxane-based adhesive layer is optically clear. The reaction mixtures and adhesive layers prepared from them are described in detail above. A wide range of laminate articles are disclosed herein. In some embodiments, the laminate article is a transfer tape, other laminate articles are intermediate articles, and still other laminate articles are optical constructions. Each of these laminate articles is described below. The laminate articles comprise a first substrate and a second substrate. A wide variety of substrates are suitable, depending upon the type of laminate article. In some embodiments, the laminate article is a transfer tape. In these articles, the first substrate and the second substrate are release liners. Transfer tapes are well understood in the art as being free-standing adhesive layers that can be laminated to substrate surfaces to prepare additional laminate articles. Release liners are well understood in the adhesive arts. Exemplary release liners include those prepared from paper (e.g., Kraft paper) or polymeric material (e.g., polyolefins such as polyethylene or polypropylene, ethylene vinyl acetate, polyurethanes, polyesters such as polyethylene terephthalate, and the like, and combinations thereof). At least some release liners are coated with a layer of a release agent such as a silicone, a hydrocarbon polymer, a fluorosilicone-containing material or a fluorocarbon-containing material. Particularly suitable release liners include the FSD5 and SS1A release liners available from Nippa. In other embodiments, the laminate article is an intermediate article. Intermediate articles are those that are used to form final articles. In intermediate articles, the first substrate is the exterior layer of a flexible display. A wide range of flexible displays are suitable such as OLEDs (organic light emitting diodes), computer monitors, TVs, cell phones and small displays (in cars, appliances, wearables, electronic equipment, etc.). Flexible electronic displays are ones in which the display can be bent freely without cracking or breaking. The exterior layer of the flexible display is typically a polymeric layer. In intermediate article embodiments, the adhesive layer can be laminated to the first substrate surface, or the reaction mixture that forms the adhesive layer can be disposed on the first substrate surface and the adhesive layer is formed on the first substrate surface. In these embodiments, the second substrate is a release liner. The release liner is removed from the adhesive layer and a substrate is laminated to the exposed adhesive surface to form the final article. An advantage of forming intermediate articles is that the intermediate article can be formed at one location or at one time, and the final article can be prepared at a different location or at a different time. In other embodiments, the laminate article is an optical construction. In these articles, the first and second substrates are optical substrates. The optical substrates may be flexible or rigid, typically at least one is flexible. Optical substrates are substrates that produce an optical effect. These optical effects include visible light transmission, visible light absorption, visible light reflection or refraction, and the like. Typically, the optical substrates are optically clear. Examples of flexible substrates include polymeric and copolymeric films. The polymeric or copolymeric films may be prepared from polyolefins, polyesters, polyurethanes, PEN, polyimides, or blends of these materials. Examples of rigid substrates include plates of glass or other optically transparent materials such as polycarbonate (PC) or polymethylmethacrylate (PMMA). To take advantage of the corrosion-resistant properties of the adhesives of this disclosure, generally at least one of the first substrate and the second substrate comprises a silver nanowire film. Typically, a silver nanowire film comprises a network of interconnected nanowires on a polymeric or copolymeric film substrate. The film substrate films may be prepared from polyolefins, polyesters, polyurethanes, PEN, polyimides, or blends of these materials. The nanowires may be partially or fully encased within an additional polymeric binder or resin layer. An embodiment of an article of this disclosure is shown in Figure 1. In Figure 1, article 100 comprises substrate layer 110 with sub-layers 111 and 112. Sublayer 111 is a film layer, and sub-layer 112 is a layer of silver nanowires dispersed in a binder. Adhesive layer 120 is disposed on sub-layer 112 and comprises the cured siloxane-based pressure sensitive adhesive described in detail above. A second substrate layer (not shown) can be disposed on adhesive layer 120. Also disclosed herein are methods of preparing laminate articles. In some embodiments, the method of preparing a laminate article comprises providing a first substrate with a first major surface and a second major surface, providing a reaction mixture for preparing a siloxane-based adhesive or a siloxane-based adhesive layer, disposing the reaction mixture or the siloxane-based adhesive layer on at least a portion of the second major surface of the first substrate, if a reaction mixture was disposed on the second major surface of the first substrate, curing the reaction mixture to form a siloxane- based adhesive layer, providing a second substrate with a first major surface and a second major surface, and disposing the first major surface of the second substrate on the siloxane-based adhesive layer. As described above in detail, the reaction mixture for preparing a siloxane-based adhesive comprises: at least one vinyl-functional siloxane; at least one hydrido-functional siloxane; at least one hydrosilylation catalyst; at least one siloxane tackifying resin; and at least one corrosion prevention agent. The reaction mixture may further comprise at least one solvent. If a solvent is present, the method further comprises a drying step to remove the solvent. Typically, the solvent is removed either simultaneously with the curing step or before the curing step. Depending upon the nature of the solvent, drying may involve heating to an elevated in temperature, for example by placing the article in an oven. In some embodiments, the drying is carried out at temperatures between about 60°C and 160°C. The drying time can also vary depending upon the nature of the solvent used as well as the drying temperature. Typically the drying time is less than 10 minutes. In some embodiments, the first substrate is a release liner, and the second substrate is also a release liner. In these embodiments, the laminate article is a transfer tape as described above. In other embodiments, the laminate article is an intermediate article. In these intermediate articles, the first substrate is the exterior layer of a flexible display. A wide range of flexible displays are suitable such as OLEDs (organic light emitting diodes), computer monitors, TVs, cell phones and small displays (in cars, appliances, wearables, electronic equipment, etc.). Flexible electronic displays are ones in which the display can be bent freely without cracking or breaking. The exterior layer of the flexible display is typically a polymeric layer. In intermediate laminate articles, the second substrate is a release liner. In some embodiments of intermediate articles, the reaction mixture is disposed on the exterior layer of a flexible display, and the reaction mixture is cured to form the siloxane-based adhesive layer. In other embodiments of the intermediate articles, a transfer tape as described above is laminated to the exterior layer of a flexible display. In other embodiments, the laminate article is an optical construction. In the optical constructions, the first substrate is an optical substrate, and the second substrate is an optical substrate. In some embodiments, the second major surface of the first substrate is the exterior layer of a flexible display. The second substrate is an optical substrate that may be flexible or rigid as described above. Typically, both the first substrate and the second substrate are optically clear. The optical constructions can be formed directly by disposing the reaction mixture on the second major surface of the first substrate, curing the reaction mixture to form a siloxane-based adhesive layer, and disposing the second substrate on the formed siloxane-based adhesive layer. Alternatively, the optical construction can be formed by forming a transfer tape article as described above, laminating the transfer tape to the second major surface of the first substrate, removing the release liner from the transfer tape to expose the siloxane- based adhesive layer, and disposing the second substrate on the exposed siloxane-based adhesive layer. Examples These examples are merely for illustrative purposes only and are not meant to be limiting on the scope of the appended claims. All parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight, unless noted otherwise. Solvents and other reagents used were obtained from Sigma-Aldrich Chemical Company; Milwaukee, Wisconsin unless otherwise noted. The following abbreviations are used: cm = centimeters; mm = millimeters; g = grams; kg = kilograms; min = minutes; h = hours. The terms “weight %”, “% by weight”, and “wt%” are used interchangeably. Table of Abbreviations Materials Description Suppliers VS Vinyl silicone-Vinyl terminated silicone Wacker (PDMS) polymer, available as DEHESIVE 948 HS Hydrido silicone-Methylhydrosiloxane- Gelest, INC. dimethylsiloxane copolymer, Morrisville, PA trimethylsiloxane terminated, available as HMS-151 Pt Cat Platinum Catalyst of PLATINUM- Gelest, INC. DIVINYLTETRAMETHYLDISILOXANE Morrisville, PA COMPLEX; 2% Pt in xylene Tack-1 MQ resin available as DOWSIL 2-7066 THE DOW Silicone CHEMICAL COMPANY, MIDLAND MI Tack-2 MQ Resin available as SR545 Momentive ACA Anti-Corrosive Agent, Benzotriazole, Cas. 95-14-7 SNW Silver nanowire films TPK Advanced Materials, Taoyuan, Taiwan Liner-1 Release liner available as FSD5 Nippa Liner-2 Release liner available as SS1A Nippa Adhesive-1 An acrylate-based OCA commercially 3M Company available as CEF1904 Test Methods Test Method 1. Dynamic Mechanical Analysis Dynamic mechanical analysis (DMA) was accomplished using an DHR3 PARALLEL PLATE RHEOMETER (TA Instruments) to characterize the physical properties of each sample as a function of temperature. For each SiOCA, approximately 0.5 g of adhesive material (after removal of the easy and tight-side release liners) was centered between 8 mm diameter parallel plates of the rheometer and compressed until the edges of the sample were uniform with the edges of the top and bottom plates. Testing was conducted using a temperature scan rate of 3°C. / min at a frequency of 1 Hertz and a maximum strain of 20%. The scans were performed from −60°C. to 120°C. While many physical parameters of the material are recorded during the temperature ramp, storage modulus (G′), loss modulus (G″), and tan delta are of primary importance in the characterization of the homopolymers of this disclosure. Testing Method 2: SNW Compatibility Tests A 3 inch (8 cm x 10 cm) section of each SiOCA (after removal of the easy-side release liner) was laminated to SNW film first, and then the backside of the SiOCA (after removal of the tight-side release liner) was laminated to LCD glass. The laminated parts were placed in autoclave oven setting at 50°C / 5Kg pressure for 20 min. The conductivity of SNW were measured using a Delcom 20J3 sheet resistance meter through non-contact mode. The initial surface resistance was recorded in ohms / square. The laminated samples were then placed in a 65°C and 90% humidity oven for 120h, 240h, and 500h, the conductivity measurements were recorded, and %R changes were used to determine the levels of compatibility. After 500hours, if R% is less than 10% change compared to initial, it was considered to have good compatibility. Test Method 3: Dielectric Constant 2.5-in x 7-in (6 x 18 cm) strips of each SiOCA were cut and equilibrated for 24 h in a controlled environment (CTH) room at 23°C and 55% relative humidity. They were then laminated to a thickness of at least 300 micrometers and the tight-side release liners replaced with easy-release liners to transfer to the dielectric measurement instrument. Three replicate disks, 40 mm in diameter, were cut from each OCA strip. Two brass disk electrodes were cleaned, and their thickness measured to 0.001 mm resolution. One release liner was removed from an OCA disk and the disk laminated to the mirror finish side of the electrode. The second release liner was removed and the mirror side of the second electrode placed on the exposed adhesive, pressing together firmly. The total thickness was measured of brass / adhesive / brass sandwich in 5 places around the disk. Based on the electrode thickness and the average thickness of the sandwich, the OCA thickness was calculated and this value used in the calculation of the dielectric constant. To measure, each replicate disk with electrodes was placed in the sample holder of an LCR meter (Keysight E4980A) using 16048A Test Leads. With a Measurement Signal Level of 1 V sweeping frequency over the range of interest, the LCR meter measured capacitance (Cp) and dissipation factor (D) for each replicate. From Cp and the geometric parameters, the dielectric constant was calculated. To measure the dielectric constant after accelerated aging, 2.5-in x 7-in (6 x 18 cm) strips of SiOCA were cut and placed in a 65°C and 90% relative humidity oven for 500 h, after removal of the easy-side release liners. They were then removed and equilibrated for 24 hrs in a CTH room at 23°C and 55% relative humidity. At that time, the strips were stacked to >300 micrometers thick and dielectric constant measured with the same procedure as above. Test Method 4: Water Vapor Transmission Rate (WVTR) SiOCA samples were cut into 3.50-in x 8-in (9 x20 cm) strips and laminated between two pieces of CELGARD film. Excess OCA was cut away from the edges of each sample. A strip 1.5 in (4 cm) wide was cut from the middle of the CELGARD stack and laminated to the sticky side of the PERMATRAN (W Model 1 / 50 G Water Vapor Permeability, Mocon) instrument mask. The sponge in the bottom tray of the instrument was dampened with deionized water. Grease was spread on the bottom plate and on the flat area around the indent for the sponge. The mask and laminated sample were placed down on the greased plate with the non-sticky side of the mask facing the grease. The two plates were aligned and placed back inside the PERMATRAN. The instrument was run for at least 2 h at 40°C and near 100% relative humidity to ensure a steady-state value for the WVTR. Examples Ex1-Ex3 and Comparative Examples CE-1 and CE-2 Silicone OCA Formulation All the silicone OCA (SiOCA) formulations were prepared by mixing the materials listed in Table 2. HS, ACA, and Pt Cat were diluted in solvents as listed in Table 1 before mixing with other materials. All the amounts listed in Table 2 are in grams. To prepare the SiOCA formulation, all the ingredients (except Pt Cat) were mixed in a 500 mL glass jar followed by the addition and mixing of Pt catalyst to the solution. The jar was rolled for 10-20 minutes to ensure proper mixing of all the ingredients. Coating and Curing The SiOCA formulations described above, were coated on release Liner-1 using a knife coater to a wet thickness of 16 mils (400 micrometers). The coatings were cured in a solvent rated oven at 120°C oven for 2 minutes. After curing the SiOCA, release Liner-2 was laminated to the open face of the SiOCA using soft rubber roller and light pressure. Liner-2 served as the easy-side release liner while Liner-1 served as the tight-side release liner. Table 1. Material Solvents Concentration of final solution with respect to solids (wt%) HS heptanes 10 ACA xylenes 0.2 Pt Cat xylenes 0.2 Table 2. Example VS HS Tack-1 Tack-2 ACA Heptanes Pt Cat # CE-1 304.31 7.38 39.70 0.0 0.0 47.07 1.54 CE-2 304.31 7.38 0.0 44.0 0.0 42.77 1.54 EX-1 304.31 7.38 39.70 0.0 3.08 47.07 1.54 EX-2 304.31 7.38 39.70 0.0 3.08 47.07 0.62 EX-3 304.31 7.38 0.0 44.0 3.08 42.77 1.54 Testing The cured OCA Compositions were tested for Rheology and Silver Nanowire Compatibility according to the test methods described above. The data are shown in Table 3 and Table 4 below. Table 3: Rheology Data Example G’ at - G’ at G’ at G’ at G’ at Tan Tan Tan Tg Number 20oC 25oC 50oC 65oC 75oC delta delta delta (oC) (Kpa) (Kpa) (Kpa) (Kpa) (Kpa) at 25 at 65 at 75 oCoCoC EX- 1 64.5 67.8 68.96 70.5 71.5 0.088 0.0845 0.084 <-60 EX-2 58.7 64.1 66.7 68.9 70.5 0.054 0.048 0.047 <-60 EX-3 65.2 60.5 60 60.8 61.4 0.075 0.067 0.067 <-60 CE-1 55.7 60 62.2 64.2 65.5 0.058 0.051 0.05 <-60 CE-2 66.3 59.2 58.6 59.26 59.8 0.079 0.071 0.07 <-60 Table 4: SNW compatibility Evaluation: % R change after 100h % R change after 240h OCA (65C / 90H) (65C / 90H) CE-1 9.37 14.83 CE-2 24.3 Adhesive-1 -4.16 -5.01 EX-1 0.77 -1.49 EX-2 0.8 1.69 EX-3 4.14 ---- Table 5: WVTR for 100-µm-thick OCA OCA WVTR (g / [m2– day]) Ex-1 468 Adhesive-1 65 Table 6: Dielectric Constant of Ex-1 Frequency (Hz) Dielectric Constant (initial) Dielectric Constant after 500 h in 65°C, 90% Relative Humidity 20 2.64 2.66 100 2.63 2.65 100,000 2.59 2.61 300,000 2.59 2.60 Comparing CE-1 and EX-1 and EX-2, it is clear that addition of anti-corrosion agents significantly improved the SNW compatibility. Acrylate-based Adhesive-1 has been proved to have good compatibility with SNW. Surprisingly, SiOCA like EX-1 can also achieve SNW compatibility even though they have WVTR more than 7 times higher than acrylate-based Adhesive-1.

Claims

What is claimed is:

1. A corrosion resistant adhesive composition comprising: a siloxane-based adhesive prepared from a reaction mixture comprising: at least one vinyl-functional siloxane; at least one hydrido-functional siloxane; at least one hydrosilylation catalyst; at least one siloxane tackifying resin; and at least one corrosion prevention agent, wherein upon curing in the form of a layer, the siloxane-based adhesive has a stable modulus as measured by DMA (Dynamic Mechanical Analysis) within a temperature range of between about -30°C to 70°C, the cured adhesive layer has a shear storage modulus at a frequency of 1 Hz that does not exceed 0.2 MPa, and wherein upon lamination of the cured siloxane-based adhesive layer to a silver nanowire film the resistance of the silver nanowire film changes by less than 10% after aging for 500 hours at 65°C / 90% relative humidity, and wherein the cured siloxane-based adhesive layer is optically clear.

2. The corrosion resistant adhesive composition of claim 1, wherein the at least one vinyl- functional siloxane is described by Formula 1:Formula 1 wherein each R1, R2, R3, and R4 are independently selected from the group consisting of an alkyl group, an aryl group and an ethylenically unsaturated group; each R5 is an alkyl group; each X is a ethylenically unsaturated group or an alkyl group; and n and m are integers, and at least one of m or n is not zero.

3. The corrosion resistant adhesive composition of claim 1, wherein the at least one vinyl- functional siloxane is described by Formula 1:wherein R1 is an ethylenically unsaturated group; each R2, R3, and R4 are independently selected from the group consisting of an alkyl group or an aryl group; each R5 is an alkyl group; each X is an alkyl group; and n and m are integers, and at least m is not zero.

4. The corrosion resistant adhesive composition of claim 1, wherein the at least one hydrido-functional siloxane is described by Formula 2: R5R1 R3R5wherein R1, R2, R3, and R4 are independently selected from the group consisting of an alkyl group, an aryl group and a hydrido group; each R5 is an alkyl group; and n and m are integers, and at least one of m or n is not zero.

5. The corrosion resistant adhesive composition of claim 1, wherein the at least one hydrido-functional siloxane is described by Formula 2:Formula 2 wherein R1 is a hydrido group, R2, R3, and R4 are independently selected from the group consisting of an alkyl group or an aryl group; each R5 is an alkyl group; and n and m are integers, and at least m is not zero.

6. The corrosion resistant adhesive composition of claim 1, wherein the at least one hydrosilylation catalyst comprises a platinum catalyst.

7. The corrosion resistant adhesive composition of claim 1, wherein the at least one siloxane tackifying resin is an MQ resin.

8. The corrosion resistant adhesive composition of claim 1, wherein the at least one corrosion prevention agent comprises a benzothiazole or substituted benzothiazole.

9. The corrosion resistant adhesive composition of claim 1, wherein upon lamination of the cured siloxane-based adhesive layer to a silver nanowire film the resistance of the silver nanowire film changes by less than 10% after aging for 500 hours at 85°C / 85% relative humidity.

10. The corrosion resistant adhesive composition of claim 1, wherein the cured siloxane- based adhesive layer has a dielectric constant of less than or equal to 2.70 when measured at 100 kHz and wherein the dielectric constant is consistent, meaning that the dielectric constant when measured at different frequencies is within 0.1 of the value when measured at 100 kHz, and wherein the dielectric constant is stable, meaning that the dielectric constant changes less than 0.1 from the original value when the adhesive is aged for 500 hours at 65°C / 90% relative humidity.

11. A laminate article comprising: a first substrate with a first major surface and a second major surface:an adhesive layer disposed on at least a portion of the second major surface of the first substrate; and a second substrate with first major surface and a second major surface, wherein the first major surface of the second substrate is disposed on the adhesive layer, wherein the adhesive layer comprises a siloxane-based adhesive prepared from a reaction mixture comprising: at least one vinyl-functional siloxane; at least one hydrido-functional siloxane; at least one hydrosilylation catalyst; at least one siloxane tackifying resin; and at least one corrosion prevention agent, wherein upon curing in the form of a layer, the siloxane-based adhesive has a stable modulus as measured by DMA (Dynamic Mechanical Analysis) within a temperature range of between about -30°C to 70°C, the cured adhesive layer has a shear storage modulus at a frequency of 1 Hz that does not exceed 0.2 MPa, and wherein upon lamination of the cured siloxane-based adhesive layer to a silver nanowire film the resistance of the silver nanowire film changes by less than 10% after aging for 500 hours at 65°C / 90% relative humidity, and wherein the cured siloxane-based adhesive layer is optically clear.

12. The laminate article of claim 11, wherein the first substrate and second substrate are release liners and the laminate article is a transfer tape.

13. The laminate article of claim 11, wherein at least one of the first and second substrates is flexible, and at least one of the first and second substrates comprises silver nanowires in contact with the adhesive layer.

14. The laminate article of claim 11, wherein the at least one vinyl-functional siloxane is described by Formula 1:Formula 1 wherein R1 is an ethylenically unsaturated group; each R2, R3, and R4 are independently selected from the group consisting of an alkyl group or an aryl group; each R5 is an alkyl group; each X is an alkyl group; and n and m are integers, and at least m is not zero.

15. The laminate article of claim 11, wherein the at least one hydrido-functional siloxane is described by Formula 2: R5R1 R3R5wherein R1 is a hydrido group, R2, R3, and R4 are independently selected from the group consisting of an alkyl group or an aryl group; each R5 is an alkyl group; and n and m are integers, and at least m is not zero.

16. The laminate article of claim 11, wherein the at least one corrosion prevention agent comprises a benzothiazole or substituted benzothiazole.

17. The laminate article of claim 11, wherein the first substrate comprises the exterior surface of an optical device, the second substrate comprises an optical substrate, and at least one of the first or second substrates comprise silver nanowires in contact with the adhesive layer.

18. A method of preparing a laminate article comprising: providing a first substrate with a first major surface and a second major surface; providing a reaction mixture for preparing a siloxane-based adhesive comprising: at least one vinyl-functional siloxane; at least one hydrido-functional siloxane; at least one hydrosilylation catalyst; at least one siloxane tackifying resin; and at least one corrosion prevention agent; or providing a siloxane-based adhesive layer; disposing the reaction mixture or the siloxane-based adhesive layer on at least a portion of the second major surface of the first substrate; curing the reaction mixture to form a siloxane-based adhesive layer if a reaction mixture is used; providing a second substrate with a first major surface and a second major surface, and disposing the first major surface of the second substrate on the siloxane-based adhesive layer.

19. The method of claim 18, further comprising a drying step simultaneous with or after curing of the reaction mixture.

20. The method of claim 18, wherein disposing the siloxane-based adhesive layer on at least a portion of the second major surface of the first substrate comprises lamination of an adhesive layer.

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