Article comprising an adhesive and film suitable for

Abstract

An article is described that includes a first substrate and a second substrate. At least one adhesive layer 10 is disposed between the first substrate and the second substrate. The article also includes a multilayer film within at least a portion of the adhesive layer. Also described is a disassembly method comprising providing an adhesively bonded article as described herein; and separating the first substrate from the second substrate by layering the (e.g., multilayer) film. In other embodiments, adhesive articles (e.g., adhesive tapes) comprising (e.g., multi-layer) films and methods of making adhesively bonded articles 15 comprising (e.g., multi-layer) films are described. Methods of reworking, repairing, reusing, or recovering one or more articles are also described.

Description

Summary of the Invention

[0001] In various industries such as automotive and electronics, adhesives are commonly used to bond components of assembled products. Due to the high cost of many of these products, modifications are sometimes desired, such as repositioning bonded components during manufacturing, removing bonded components to repair the product, or disassembling bonded components for recycling. Mechanically removing adhesively bonded substrates using existing methods can damage the substrate and sometimes render the product inoperable. Therefore, industries find advantages in products and methods suitable for disassembly.

[0002] In one embodiment, an article is described comprising a first substrate and a second substrate. At least one adhesive layer is disposed between the first substrate and the second substrate. The article also includes a (e.g., multilayer) film located within at least a portion of the adhesive layer. In some embodiments, the (e.g., multilayer) film has an interlaminar peel strength of at 23°C of at least 10 g / inch, 50 g / inch, 100 g / inch, 200 g / inch, or 500 g / inch (2.54 cm).

[0003] In another embodiment, an article is described comprising a first substrate and a second substrate. At least one adhesive layer is disposed between the first substrate and the second substrate. The article also includes a membrane located within at least a portion of the adhesive layer. The adhesive layer has a bond strength greater than the interfacial strength of the membrane, and the adhesive layer has a bond strength greater than the interfacial strength of the membrane.

[0004] In another embodiment, a method of disassembly is described, comprising providing an article as described herein; and separating a first substrate from a second substrate by delaminating (e.g., a multilayer) film. In some embodiments, the delamination is performed by splitting the multilayer film. Due to the choice of adhesive, the (e.g., splitting) force used to delaminate the (e.g., multilayer) film of the article may be greater than the (e.g., the interlayer peel strength of the (e.g., multilayer) film.

[0005] In another embodiment, an adhesive article is described, comprising a (e.g., multilayer) film having a first main surface and opposing main surfaces. A first adhesive layer is disposed on the first main surface of the multilayer film; and optionally, a second adhesive layer is disposed on a second main surface of the multilayer film.

[0006] In another embodiment, a method of manufacturing an article is described, the method comprising bonding a first substrate to a second substrate with at least one adhesive layer; wherein at least one (e.g., multilayer) film is located within at least a portion of the adhesive layer. The adhesive layer and the multilayer film may be applied sequentially to the first substrate and / or the second substrate. In some embodiments, at least one adhesive layer, together with the (e.g., multilayer) film, is provided as an adhesive article (e.g., tape). The same general steps for manufacturing new articles may be performed in methods of reworking defective articles, repairing articles, reusing articles, and recycling articles.

[0007] In some embodiments, the article is subjected to temperatures of at least 60°C or 70°C during normal use. In some embodiments, the first substrate and optionally the second substrate comprise metals in contact with the adhesive layer. In some embodiments, the article is a battery. Multilayer films typically have a Tg of at least 60°C, 70°C, 80°C, 90°C, 100°C, 115°C, 120°C, or 125°C.

[0008] (For example, a multilayer) film may completely or partially span the adhesive layer. (For example, a multilayer) film may be present at one or more edge regions of the adhesive layer. When (for example, a multilayer) film partially spans the adhesive layer, the adhesively bonded article and adhesive article (for example, tape) may also include an electrical insulating layer (for example, monolithic or multilayer) spanning the adhesive layer.

[0009] In some embodiments, the adhesive layer is recessed relative to the edges of the first and second substrates. A (e.g., multilayer) film may be disposed between a first adhesive layer that bonds the first substrate to the (e.g., multilayer) film and a second adhesive layer that bonds the second substrate to the multilayer film. The first adhesive layer comprises the same or a different adhesive composition as the second adhesive layer. In some embodiments, the first adhesive layer and optionally the second adhesive layer have specified physical properties (e.g., Young's modulus, lap shear strength) as described herein.

[0010] In some embodiments, the adhesive layer (e.g., of a method or adhesive article) comprises a curable adhesive comprising a (meth)acrylate portion, a polyurethane portion, an epoxy portion, or a combination thereof.

[0011] In another embodiment, an article is described comprising a substrate, an adhesive layer disposed on the substrate, and a layered (e.g., multilayer) film bonded to the adhesive layer.

[0012] Methods for manufacturing, reworking, repairing, reusing, or recycling articles are also described. In one embodiment, the method includes providing a portion of a first article comprising a first substrate, an adhesive layer disposed on the substrate, and a layered (e.g., multilayer) film bonded to the adhesive layer. The method also includes applying an adhesive to a first substrate, a second substrate, or a combination thereof; and bonding the first substrate to the second substrate with the adhesive to form a second article. In some embodiments, the method further includes applying a monolithic film or a multilayer film to at least a portion of the adhesive layer.

[0013] In some embodiments, the method is repeated at least 2, 3, or 4 times. In one embodiment, the same membrane may be delaminated and adhesively bonded at least 2, 3, or 4 times. In another embodiment, two or more membranes are each delaminated and adhesively bonded at least once. Attached Figure Description

[0014] Figure 1A It is a cross-sectional view of an article comprising a multilayer film spanning an adhesive layer; Figure 1B It is a cross-sectional view of another article including a multilayer film that partially spans the adhesive layer; Figure 2 This is a cross-sectional view showing how the product is disassembled by splitting the multilayer film; Figure 3 It is a cross-sectional view of a multilayer film that completely spans the adhesive layer of the product; Figure 4 It is a cross-sectional view of a multilayer film that partially spans (e.g., edge localization) the adhesive layer of the article; Figure 5 It is a cross-sectional view of an article comprising a multilayer film that completely spans an adhesive layer recessed relative to a substrate. Figure 6 It is a cross-sectional view of an article comprising a multilayer film, the multilayer film portion spanning (e.g., edge localization) an adhesive layer recessed relative to a substrate; Figure 7 The substrate used to prepare the test sample for the splitting test is depicted; Figure 8 It is a cross-sectional view of an article of a multilayer film that spans the adhesive layer completely and is used for overlap shear testing; Figure 9 This is a cross-sectional view of an electrochemical cell bonded to a first substrate and a second substrate by an adhesive layer comprising a multilayer film that spans the entire length of the cell. Figure 10 It is a cross-sectional view of two or more layers of film; Figure 11 It is a cross-sectional view of a four-layer multilayer membrane; Figure 12AIt is a schematic top or front plan view of a multilayer film, which includes recessed tabs corresponding to the split locations between layers; Figure 12B It is a schematic sectional view along line 12B-12B; Figure 13 It is the cross-section of an article (e.g., tape) that includes multiple layers of film and adhesive layers; Figure 14 It is a cross-section of an article (e.g., tape) that includes an adhesive layer on both main surfaces of a multilayer film; Figure 15 It is a cross-section of an article (e.g., tape) that includes an adhesive layer that partially spans the adhesive layer and the insulating layer; Figure 16 This is a cross-sectional view of an electrochemical cell in which multiple layers of adhesive, including multilayer films, are bonded together and attached to a cooling plate. Figure 17 It is a cross-sectional view of an article comprising a film that completely spans the adhesive layer (e.g., multiple layers) for use in the overlap shear strength test method 2. Figure 18 It is a cross-sectional view of an article comprising a film that completely spans the adhesive layer (e.g., multiple layers) for the lap shear strength test method 3. Figure 19 It is a cross-sectional view of an article comprising a split (e.g., multilayer) film and a second (e.g., multilayer) film spanning an adhesive layer, used in lap shear strength test method 4. Figure 20 It is a cross-sectional view of an article comprising two (e.g., multiple) films spanning an adhesive layer, used in splitting strength test method 5; Figure 21 Methods for repairing artifacts are described. Detailed Implementation

[0015] Figure 1AThis is a cross-sectional view of an article 100, which includes a first substrate 110 bonded to a second substrate 120 by adhesive layers 131 and 132. A multilayer film 140 includes at least two distinct layers within the adhesive layers 131 and 132. The multilayer film may completely or partially span the adhesive layers. When the multilayer film completely spans the adhesive layers, as depicted in FIG. 1, the multilayer film divides the adhesive layers into a first adhesive layer 131 and a second adhesive layer 132. Therefore, the multilayer film 140 is disposed between the first adhesive layer 131, which bonds the first substrate 110 to the multilayer film 140, and the second adhesive layer 132, which bonds the second substrate 120 to the multilayer film 140. The first adhesive layer 131 contains the same or a different adhesive composition as the second adhesive layer 132. Edges 141 of the multilayer film may be exposed at two opposing edges of the article (i.e., the outer boundaries of an object, area, or surface), as depicted in FIG. 1. When the multilayer film completely spans the adhesive layers, the multilayer film extends from one edge of the adhesive layer to the other in both the x and y directions. Therefore, multiple layers exist around the entire periphery of the adhesive layer of the product.

[0016] In other embodiments, the multilayer film partially spans the adhesive layer. In this embodiment, the multilayer film may be present at one edge of the adhesive layer in the x-direction and / or y-direction, such as... Figure 4 and Figure 6 As depicted. In other embodiments, when multilayer films such as Figure 1B When fully embedded in the adhesive layers, the multilayer film 140 partially spans adhesive layers 131 and 132. In this embodiment, when the multilayer film is fully embedded, all edges 141 of the multilayer film are surrounded by adhesive.

[0017] Figure 2A cross-sectional view of a disassembled article 200 is depicted, comprising: a first substrate 210 bonded to a second substrate 220 by adhesive layers 231 and 232; and a multilayer film 240 spanning the adhesive layers 231 and 232. The substrates 210 and 220, the multilayer film 240, and the adhesive layers 231 and 232 may have a length (i.e., the longest dimension) in the x-direction, a width in the y-direction, and a thickness in the z-direction. When opposing tensile forces are applied in a direction substantially parallel to the z-direction of the multilayer film 240, the multilayer film delaminates at the interfaces between its layers. Therefore, the adhesive layers do not separate from the film, do not separate from the substrate, and do not cohesively separate. In some embodiments, delamination can be initiated by a tool that applies a wedge force in a direction substantially parallel to the x-direction (depicted) or y-direction (not depicted) of the multilayer film. In typical embodiments, delamination of the multilayer film is performed at room temperature (23°C), but delamination can be performed at other temperatures, such as temperatures above 23°C. If higher temperatures are used, the temperatures are typically below 65°C, 60°C, 55°C, 50°C, 45°C, 40°C, 35°C, or 30°C; therefore, below the temperatures suitable for thermal debonding. Debonding occurs when the bond strength between adhesive layers 231 and 232 and (e.g., multilayer) membrane 240 (e.g., at 23°C) is greater than the interfacial strength of multilayer membrane 240 (e.g., at 23°C). Additionally, the bond strength between adhesive layers 231 and 232 and substrates 210 and 220 (e.g., at 23°C) is also greater than the interfacial strength of (e.g., multilayer) membrane 240 (e.g., at 23°C). Therefore, debonding does not require methods such as subjecting the adhesive layers to radiation (e.g., light), heat, electricity, chemical agents (e.g., solvents or by reaction), magnetic fields, or acoustic energy (e.g., ultrasound). Generally, the term debonding means separation into two layers. More specifically, the membrane has two main surfaces and a thickness in a direction orthogonal to the main surfaces. The membrane is delaminated between its main surfaces in a direction generally parallel to the membrane's main surfaces, rather than in a direction parallel to its thickness. The "interfacial strength" of a membrane refers to the strength of the membrane (e.g., monolayer or multilayer) between its main surfaces under any (e.g., specified) load conditions.

[0018] Figure 3This is a cross-sectional view of an article 300, which includes a first substrate 310 bonded to a second substrate 320 by adhesive layers 331 and 332. A multilayer film 340 is located within the adhesive layers 331 and 332. The multilayer film 340 has a length and width dimension greater than or equal to that of the adhesive layers 331 and 332. The multilayer film 340 may also extend beyond the dimensions of the substrates 310 and 320 and the adhesive layers 331 and 332, thereby creating unbonded portions. These unbonded multilayer film portions may be characterized as tabs. The multilayer film tabs may be at least partially delaminated at the interface between two different layers forming a pair of tabs. Figures 4 to 5 , Figure 8 and Figures 12A to 12B Articles including specific embodiments of tabs are also depicted. Articles may have exposed tabs along one side of the bonded article, such as... Figure 3 and Figure 4 As shown. The article may have a recessed tab along one side of the bonded article, such as Figure 5 and Figure 6 As shown. Additionally, the article may optionally have (exposed and / or retracted) tabs on opposite sides of the bonded article, such as... Figure 5 and Figure 8 As shown in B. The tabs facilitate the detection of delamination / split locations during disassembly. For example, a tool for applying a wedge force can be positioned above, below, or between a pair of tabs. In embodiments where the adhesive is pressure-sensitive prior to curing, a pair of tabs can facilitate disassembly before curing for repositioning during the manufacture of the bonded article. It is worth noting that some structural adhesives are pressure-sensitive prior to curing.

[0019] The article may have various arrangements of multilayer films within the adhesive layer. Figure 1 depicts a multilayer film 140 that completely spans the adhesive layer. Therefore, as depicted in the cross-section, the length of the multilayer film is at least equal to the length of the adhesive layer. Additionally, but not depicted in the cross-section, the width of the multilayer film is at least equal to the width of the adhesive layer. Thus, when the multilayer film completely spans the adhesive layer, the adhesive layer is divided into a first adhesive layer 131 and a second adhesive layer 132.

[0020] In some embodiments, the first adhesive layer 131 (231, 331, 431, 531, 631, 831, 931, 1331, 1431) and the second adhesive layer 132 (232, 332, 432, 532, 632, 832, 932, 1432) may contain the same adhesive composition. In other embodiments, the first adhesive layer 131 and the second adhesive layer 132 may contain different adhesive compositions. The thickness of each adhesive layer 131 and 132 is typically independently at least 0.025 mm, 0.05 mm, 0.1 mm, 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, or 2 mm. The thickness of each adhesive layer 131 and 132 is typically independently no greater than 5 mm, 4 mm, 3 mm, 2 mm, 1 mm, or 0.5 mm. Figure 2 , Figure 3 , Figure 5 , Figure 8 , Figure 9 , Figure 13 and Figure 14 Multilayer films (240, 340, 540, 840, 940, 1340 and 1440) that span the entire adhesive layer are also depicted.

[0021] Figure 4 and Figure 6 The images are cross-sectional views of articles 400 and 600, which include a first substrate (410, 610) bonded to a second substrate (420, 620) by an adhesive layer (431, 432, 631, 632). Figure 4 and Figure 6 Multilayer films 440 and 640 partially spanning the adhesive layer are depicted. As depicted in cross-section, the lengths of multilayer films 440 and 640 are less than the length of the adhesive layer. The width of the multilayer film may be equal to or less than the width of the adhesive layer. When multilayer films 440 and 640 partially span the adhesive layer, the adhesive layer is separated into first adhesive layers 431 and 631 and second adhesive layers 432 and 632 at one or more locations where the multilayer film is present within the adhesive layer. In some embodiments, the first adhesive layer and the second adhesive layer may contain the same adhesive composition. In this embodiment, the same adhesive layers 430 and 630 and the same adhesive composition contact the first substrate (410, 610) and the second substrate (420, 620) at one or more locations where the adhesive layer does not contain the multilayer film. In other embodiments, the first adhesive layer (431, 631) and the second adhesive layer (432, 632) may contain different adhesive compositions.

[0022] In some embodiments, at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the adhesive layer relative to the xy plane comprises a multilayer film. In some embodiments, no more than 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, or 10% of the adhesive layer relative to the xy plane comprises a multilayer film. In some embodiments, the presence of the multilayer film in the x-direction (i.e., also referred to as the penetration distance) is at least 1 cm, 1.5 cm, 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, or 5 cm. In some embodiments, more than 0.5 inches or more than 17% of the adhesive layer relative to the xy plane comprises a multilayer film.

[0023] exist Figure 4 and Figure 6 In one embodiment, the adhesive layer can be described as having a central region disposed between two edge regions (left and right), and a multilayer film is present at one edge region (left, as depicted). In another embodiment, the adhesive layer can be described as having a central region disposed between two edge regions, and a multilayer film is present at both edge regions.

[0024] Figure 5 This is a cross-sectional view of an article 500, which includes a first substrate 510 bonded to a second substrate 520 by adhesive layers 531 and 532. A multilayer film 540 extends completely across the adhesive layers. In this embodiment, the multilayer film 540, as well as the adhesive layers 531 and 532, are recessed relative to the outer edges of the substrates 510a and 510b. Figure 6 A multilayer film 640 and adhesive layers 631 and 632 are depicted, spanning a portion recessed relative to the outer edge of the substrate. Figure 5 and Figure 6 In this embodiment, the indentation dimension is 1 inch. In some embodiments, the adhesive layer, alone or in combination with the multilayer film, is indented in the x-direction by at least 1 cm, 1.5 cm, 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, or 5 cm. In some embodiments, the indentation dimension in the x-direction relative to the substrate is at least about 10%, 15%, 20%, 25%, or 30%. In some embodiments, the indentation dimension in the x-direction relative to the substrate is no greater than 10%, 15%, 20%, 25%, or 30%. The indentation of the adhesive layer, alone or in combination with the multilayer film, may be advantageous for inserting tools (e.g., wedges) to pry open the substrate with a splitting load. It is worth noting that the indentation may also provide a lower splitting strength compared to the same article without indentation.

[0025] Additional layers (not shown) are also included within the scope of the articles described herein, which include more than one multilayer film that spans entirely or partially across the adhesive layer.

[0026] In typical implementations, the multilayer film and adhesives exhibit high heat resistance. High heat resistance is particularly important for products that may be subjected to temperatures ranging from at least 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C to up to, for example, 200°C during normal use. For example, electric vehicle (EV) batteries are designed to maintain an ideal battery cell temperature between 68°F and 113°F (20°C to 45°C). Sometimes, EV batteries reach lower or higher temperatures during normal operation, such as -10°C to 60°C. However, EV batteries may be unintentionally exposed to higher temperatures during a failure, such as during thermal runaway.

[0027] In some embodiments, the glass transition temperature (Tg) of the multilayer film (or at least one layer thereof or its material) is typically at least 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 115°C, 120°C, or 125°C. In some embodiments, the Tg of the multilayer film (or at least one layer thereof or its material) is not greater than 125°C, 120°C, 115°C, or 100°C. For example, the multilayer film may include a layer of polyethylene naphthalate (PEN), which is a semi-crystalline polymer with a Tg in the range of 110°C to 120°C. In some embodiments, the Tg of the multilayer film (or at least one layer thereof or its material) is not greater than 95°C, 90°C, 85°C, 80°C, 75°C, or 70°C. For example, a multilayer film may comprise a copolyester of polyethylene terephthalate and polyethylene terephthalate with a Tg in such a range. The melting temperature of the multilayer film (or at least one layer thereof or its material) is typically at least 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, or 280°C. In some embodiments, the melting temperature of the multilayer film (or at least one layer thereof or its material) is not greater than 270°C, 260°C, 250°C, 240°C, 230°C, 220°C, 210°C, 200°C, 190°C, 180°C, or 170°C. For example, a multilayer film comprising a polyolefin (such as (e.g., isotactic) polypropylene) has a melting temperature in the range of 160°C–170°C. Polyolefins typically have a Tg of less than 0°C, -10°C, or -20°C. Tg and Tm can be measured using differential scanning calorimetry according to ASTM D3418.

[0028] Multilayer films typically comprise at least two layers containing different thermoplastic polymers. Multilayer films typically exhibit at least two thermoplastic glyphs (Tg). When a multilayer film has more than two layers, and the respective layers contain different thermoplastic polymers, different Tgs may exist for each different thermoplastic polymer. In some embodiments, the different thermoplastic polymers have similar Tgs, resulting in a wider transition in calorimetric measurements of the Tg of the two or more different thermoplastic polymers covering the multilayer film. In some embodiments, the Tg of the multilayer film is at least 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 115°C, 120°C, or 125°C. Therefore, in some embodiments, the Tg of the multilayer film is not less than a Tg of 125°C, 120°C, 115°C, 110°C, 100°C, 95°C, 90°C, 85°C, 80°C, 75°C, or 70°C.

[0029] When the adhesive is a curing adhesive such as a curing epoxy resin, the adhesive is not thermoplastic and therefore does not typically exhibit a melting temperature. Instead, such cured adhesives typically decompose at high temperatures rather than exhibiting such a thermal transition. The cured resins that form the insulating film are also not thermoplastic. Therefore, the layers of a multilayer film that splits during mechanical disassembly are typically not a cured (e.g., resin) composition.

[0030] In typical embodiments, the multilayer film and (e.g., cured) adhesive have high chemical resistance. In some embodiments, the bonded article comprising the multilayer film, (e.g., cured) adhesive, and substrate may be exposed to chemical agents such as acidic or alkaline solutions, corrosive salt solutions, solvents, or oxidizing substances such as peroxides. For example, adhesively bonded substrates on the structure of an automotive body need to withstand salt exposure. Adhesively bonded substrates in consumer electronics devices may need to withstand exposure to cleaning agents, such as detergents or light solvents applied by the user. The material composition of the multilayer film and adhesive layers can be selected based on the chemical resistance requirements of the intended application. In another consideration of chemical resistance, solvents or other chemical agents have been applied to intentionally weaken the bond in order to disassemble adhesively bonded joints. This chemical disassembly method has the disadvantage of undesirable long contact or immersion times (e.g., typically several hours). Therefore, the currently disclosed invention provides an advantageous alternative to the chemical weakening of adhesive bonds for disassembly.

[0031] Disassembly method

[0032] In one embodiment, a disassembly method is described, comprising providing an article as described herein, wherein a first substrate is bonded to a second substrate with an adhesive layer, and the adhesive layer further comprises, for example, a multilayer film; and applying a force to separate the first substrate from the second substrate by delaminating the multilayer film. The presence of the multilayer film reduces the disassembly force compared to an article that is adhesively bonded in the same way but lacks at least partially a multilayer film spanning the adhesive layer. As shown in the following example, the presence of the multilayer film reduces the splitting strength and lap shear strength compared to a substrate that is adhesively bonded in the same way but lacks the multilayer film within the adhesive layer.

[0033] The membrane is delaminated, i.e., divided into two layers. (E.g., multilayer) The membrane can be delaminated along a common interface. In this embodiment, each layer can have a uniform thickness (+ / - 10% of the average thickness). Alternatively, the membrane can be initially delaminated along a first plane (e.g., an interface) and also along other planes (e.g., interfaces) during disassembly. In this embodiment, each layer can have a uniform thickness or a thickness variation greater than 10%.

[0034] Preferably, at least one or both substrates are not damaged during disassembly. When a substrate (e.g., a battery electrochemical cell) is damaged, it cannot be reused. EV battery cells that are no longer suitable for a vehicle because they can no longer store a useful proportion of their original charge can still be used for other purposes, such as storing energy generated by intermittent sources (e.g., from solar panels including photovoltaic modules). Using EV battery cells for such other purposes is referred to herein as reuse.

[0035] In some embodiments, a splitting force is used to separate the first substrate from the second substrate. Splitting is a load condition applicable to adhesively bonded substrates, thereby applying a normal separation force at or outside the edge of the bonded area. Splitting load conditions can be generated by inserting a wedge into or near the bonded edge, or by joining the substrates of the bonded article at or near the edge of the bonded area, for example using a double cantilever specimen, as is known in the art. A splitting load condition is characterized by the separation stress being concentrated at the edge of the bonded area.

[0036] While splitting has been exemplified as a disassembly load condition, it is presumed that multilayer membranes can provide reduced disassembly forces under other load conditions. For example, forces applied at an angle (e.g., 5 or 10 degrees) instead of zero degrees (i.e., splitting) would also be expected to delaminate multilayer membranes. Furthermore, other separation rates can be suitable and controlled by using robotic disassembly.

[0037] In some embodiments, the adhesively bonded article can withstand a first load condition (e.g., overlap shear) related to the usage conditions of the article, and the multilayer film provides a means for separating (removing) the first substrate from the second substrate using a second load condition different from the first load condition (e.g., splitting). In other embodiments, the multilayer film provides a means for separating (removing) the first substrate from the second substrate using shear as a second load condition.

[0038] The average (e.g., splitting and lap shear) strength of bonded articles (e.g., including test samples) can vary depending on the choice of (e.g., multilayer) film, the materials of the adhesive layers (e.g., their Young's modulus), the bonding design (e.g., whether there is indentation) and the mechanical behavior of the substrate (e.g., stiffness).

[0039] In some embodiments, the average splitting strength is less than 5000 N / inch, 4000 N / inch, 3000 N / inch, 2000 N / inch, 1500 N / inch, 1000 N / inch, 750 N / inch, 500 N / inch, or 250 N / inch. In some embodiments, the average splitting strength is at least 10 N / inch, 20 N / inch, 30 N / inch, 40 N / inch, 50 N / inch, 75 N / inch, 100 N / inch, or 150 N / inch. As described above, a low splitting strength may be preferred for easy and intentional removal of adhesively bonded articles. In some embodiments, the average splitting strength is at least 250 N / inch, 500 N / inch, 750 N / inch, or 1000 N / inch. Higher splitting strengths are suitable for robotic removal. The average relative splitting strength is determined by dividing the average splitting strength of a substrate with the same adhesive bonding having a multilayer film by the average splitting strength of a control (i.e., a substrate with the same adhesive bonding without a multilayer film) and multiplying by 100%. The average relative splitting strength is typically less than 80%, 70%, 60%, 50%, 40%, 30%, or 20%. In some embodiments, the average relative splitting strength is at least 1%, 2.5%, 5%, 10%, 20%, 30%, 40%, or 50%. In some embodiments, a lower relative average splitting strength is desirable, or in other words, the average splitting strength is significantly reduced due to the presence of (e.g., multilayer) films. However, for robotic disassembly, a higher relative average splitting strength, especially in combination with a higher lap shear strength, may be desired.

[0040] In some embodiments, the average lap shear strength is at least 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 5 MPa, 10 MPa, 15 MPa, or 20 MPa. In some embodiments, the average lap shear strength is not greater than 30 MPa, 25 MPa, 20 MPa, 15 MPa, 10 MPa, or 5 MPa. The lap shear strength values ​​reported herein were measured at an ambient temperature of 23°C. In typical embodiments, the lap shear strength is between 1 MPa and 20 MPa, between 1.5 MPa and 15 MPa, or between 2 MPa and 10 MPa. High lap shear strength may be preferred for bonded articles to withstand loads during normal operation. The average relative shear strength is determined by dividing the average shear strength of a substrate with the same adhesive bonding having a multilayer film by the average shear strength of a control (i.e., a substrate with the same adhesive bonding without a multilayer film) and multiplying by 100%. When a multilayer film at least partially spans the adhesive layer, the average relative lap shear strength can be 100%, or in other words, the lap shear strength does not decrease (or increase). In some embodiments, the average relative lap shear strength is less than 90%, 80%, 70%, 60%, 50%, 40%, 30%, or 20%. In some embodiments, the average relative lap shear strength is at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%. Lap shear values ​​of 1 MPa to 5 MPa are generally acceptable for semi-structural bonding, as can be found inside smartphone devices.

[0041] In some embodiments, (e.g., multilayer) membranes may include slits or small gaps to increase the adhesive strength of the membrane (e.g., lap shear), and some exemplary slit patterns are shown in US 9,821,529, which is incorporated herein by reference.

[0042] Depending on the force required to initiate splitting, the article can be disassembled manually, but more typically by using tools or machines that provide mechanical assistance. Mechanical assistance can take the form of, for example, a pulling separation force applied to the substrate or the insertion and actuation (e.g., by rotating or bending a prying tool) between the substrates. For example, the machine can be powered by electromechanical or hydraulic devices. In some embodiments, the machine can be adapted for automated robotic disassembly, such as using machine vision, machine learning, grippers, and manipulators including actuators.

[0043] The product is typically disassembled at ambient temperature (23°C + / -15°C, + / -10°C, or + / -5°C). However, disassembly can be performed at lower or higher temperatures. Generally, the temperature is below the melting temperature of the film.

[0044] The disassembly method provides disassembled products including reworked products, repaired products, reused products and recycled products.

[0045] In one embodiment, the article includes (e.g., a battery module) a first substrate, an adhesive layer disposed on the substrate, and a layered (e.g., multilayer) film bonded to the adhesive layer. The layered film may be part of a layer of the (e.g., multilayer) film before removal.

[0046] In another embodiment, a method for manufacturing, reworking, repairing, reusing, or recycling an article is described, the method comprising providing a portion of a first article comprising a first substrate, an adhesive layer disposed on the substrate, and a layered (e.g., multilayer) film bonded to the adhesive layer. The method further comprises applying an adhesive to the first substrate, a second substrate, or a combination thereof; and bonding the first substrate to the second substrate with the adhesive to form a second article.

[0047] In some embodiments, the method further includes applying a monolithic or multilayer film to at least a portion of the adhesive layer. In some embodiments, the film and at least one adhesive are applied as a tape.

[0048] In some embodiments, the method is repeated at least 2, 3, or 4 times. In some embodiments, identical (e.g., multilayer) films are layered and adhesively bonded at least 2, 3, or 4 times. In other embodiments, two or more films are each layered and adhesively bonded at least once.

[0049] In some embodiments, the total thickness of the layered film, the adhesive applied to the layered film, and the applied monolithic or multilayer film is within 50%, 40%, 30%, 20%, or 10% of the thickness of the multilayer film in the first article.

[0050] In some embodiments, the total thickness of the layered film, the adhesive applied to the layered film, and the applied monolithic or multilayer film is + / - 0.5 mm, 0.25 mm, 0.1 mm, or 0.05 mm of the thickness of the multilayer film of the first article.

[0051] In some embodiments, the first article has a first adhesive thickness between the first substrate and the second substrate, and the applied adhesive and film are selected such that the adhesive thickness between the first substrate and the second substrate of the second article is + / - 10% of the first adhesive thickness.

[0052] This method can provide reworked or repaired (e.g., battery module) articles comprising a first substrate; a second substrate; and one or more adhesive layers disposed between the first and second substrates to define a bond thickness. The reworked or repaired (e.g., battery module) article has a bond thickness of + / - 10% compared to the article before rework or repair.

[0053] In some implementations, the reworked or repaired article (e.g., a battery module) also includes a membrane located within at least a portion of the adhesive layer.

[0054] The bonded article can be disassembled for the first time using a first splitting strength, and for the second time using a second splitting strength. In some embodiments, the same bonded article can be disassembled for the third, fourth, and fifth times using a third, fourth, and fifth splitting strength. The second, third, fourth, and fifth splitting strengths can be described as subsequent splitting strengths.

[0055] The first splitting strength and one or more subsequent splitting strengths (e.g., second, third, fourth, fifth, or combinations thereof) may be the same or substantially the same (e.g., within + / - 10% of the average of the first splitting strength). In other embodiments, the first splitting strength and one or more subsequent splitting strengths may differ by less than + / - 50%, + / - 40%, + / - 30%, or + / - 20% of the average of the first splitting strength. In some embodiments, the decrease in splitting strength from the first splitting strength to the subsequent splitting strength provides sufficient strength for reworking, repairing, or recycling the article. In some embodiments, the increase in splitting strength from the first splitting strength to the subsequent splitting strength is not excessive, such that it would prevent subsequent reworking, repairing, reuse, or recycling of the adhesively bonded article.

[0056] When an adhesive article comprises different films or a multilayer film containing layers with different splitting strengths, the adhesive article may have two or more different splitting strengths. The splitting strengths may differ (increase or decrease) by, for example, 500 times, 250 times, 100 times, 50 times, 25 times, 10 times, 5 times, or 2 times.

[0057] Figure 21 The figure illustrates an exemplary repair method, depicting from left to right the removal of the original bonded article and the replacement of the original substrate 2 with substrate 2B using adhesive 2B and repair tape. Substrate 2 may be, for example, a defective component. The original bonded article includes substrate 1 adhesively bonded to the membrane (original "MSF") with original adhesive 2131 and substrate 2 adhesively bonded to the membrane (original "MSF") with adhesive 2. In some embodiments, substrate 2 (and substrate 2B) is a cooling plate or cover. In some embodiments, adhesive 2 (and adhesive 2B) is a thermally conductive adhesive. In some embodiments, substrate 1 is a battery cell.

[0058] The original adhesive 2131 of the original bonded article has bond strength to the substrate 1 and bond strength to the membrane (original "MSF"). The adhesive 2 of the original bonded article has bond strength to the substrate 2 and bond strength to the membrane (original "MSF"). Such bond strength is greater than the interfacial strength of the membrane at ambient temperature. Therefore, the original bonded article can be disassembled by interfacial membrane failure (i.e., delamination) at ambient temperature rather than by adhesive failure.

[0059] The original adhesive article may consist of a single-sided original adhesive tape comprising an initial adhesive 2131 disposed on the multilayer film. For simplicity, the multilayer film is depicted as having two layers, film layer 2141 and film layer 2142.

[0060] When the membrane is a multilayer membrane, the original bonded article can be removed by separating membrane layer 2141 from the second membrane layer 2142. The substrate 2, which is held bonded to membrane layer 2142 with adhesive 2, is separated from the substrate 1, which is held bonded to membrane layer 2141 with the original adhesive 1. The substrate 2, which is held bonded to membrane layer 2142 with adhesive 2, is removed (e.g., discarded).

[0061] The repair involves replacing substrate 2 with substrate 2B. For the repair, substrate 2B is bonded to the film (repair “MSF”) of the repair tape using adhesive 2B. The repair tape also includes a repair adhesive that contacts and bonds to the film layer 2141 of the original adhesive article. Film layer 2141 remains bonded to substrate 1 using the original adhesive 2131. The film (repair “MSF”) can be a single-layer film or a multilayer film. For simplicity, the repair “MSF” is depicted as a multilayer film having two layers (film layer 2241 and film layer 2242).

[0062] The original adhesive 2131 of the original bonded article has bond strength to the substrate 1 and bond strength to the membrane (original "MSF"). The adhesive 2B of the repair article has bond strength to the substrate 2B and bond strength to the membrane (repair "MSF"). The repair adhesive has bond strength to the membrane layer 2141 and the membrane of the repair "MSF". When the bond strength is greater than the interfacial strength of the membrane at ambient temperature, the repair article can be disassembled by membrane failure at ambient temperature rather than adhesive failure.

[0063] Each of the adhesive layer and the film layer has a specified thickness. In some embodiments, the thickness of the adhesive applied to the layered film and the thickness of the applied monolithic or multilayer film (e.g., for repair tape) are selected such that, when combined with the thickness of the layered film (e.g., 1241), the total thickness is within 50%, 40%, 30%, 20%, or 10% of the thickness of the first article (e.g., multilayer) film (original “MSF”) prior to layering.

[0064] In some embodiments, the thickness of the adhesive applied to the layered film and the thickness of the applied monolithic or multilayer film (e.g., for repair tape) are selected such that, when combined with the thickness of the layered film (e.g., 1241), the total thickness can be within 1 mm (0.5 mm, 0.25 mm, 0.1 mm, 0.05 mm) of the thickness of the original (e.g., multilayer) film (original “MSF”) of the first article prior to layering.

[0065] It should be understood that even when the original bonded article initially lacks a multilayer film, it can be repaired using a repair film and repair adhesive as described herein. For example, an original bonded article lacking a multilayer film can be disassembled by using heat or electric current to detach the adhesive. In this embodiment, the original bonded article will not include (e.g., a multilayer) film, and therefore no film layer will be present after separating substrate 1 from substrate 2. The repaired article will include (e.g., a multilayer) film, with no remaining film portions (e.g., film layer 1241 of a layered multilayer film).

[0066] Adhesive products

[0067] Various adhesively bonded articles can be prepared, comprising a multilayer film that at least partially spans an adhesive layer adhered to a first substrate and a second substrate. In some embodiments, the common adhesive layer can bond to more than two substrates. For example, a single cooling plate can be adhesively bonded to more than one electrochemical cell (each electrochemical cell can be considered a substrate).

[0068] A wide variety of organic and inorganic substrates can be used, including, for example, polymers, metals, composites, ceramics, glass, and combinations thereof, including composites. Metals and metal surfaces include steel and coated steel, such as stainless steel, tin-free steel, tin-plated steel, nickel-plated steel, copper-clad stainless steel, and electrolytic chromium-coated steel (ECCS); aluminum and aluminum alloys; copper; bronze; titanium and titanium alloys; magnesium and magnesium alloys.

[0069] In some implementations, the substrate can be considered rigid. For example, a ¼-inch (0.635 cm) aluminum sheet used to evaluate splitting strength is rigid. However, the same testing method is also used to evaluate thinner, more flexible substrates, such as 0.9 mm aluminum sheets. Even when the substrate is bent after the test, a decrease in splitting strength is observed.

[0070] The substrate can be flat or curved. The substrate can be a component that may include a variety of materials. Exemplary substrates include electrochemical cells, structural components (e.g., housings, covers, lateral members, or other support members in a battery pack, such as that of an automobile or more specifically an EV), thermal management components (e.g., cooling plates or thermal barriers of an EV battery pack), and electrical components (e.g., busbars, leads, circuit boards, chip carriers, power modules, display modules, motor stators, and motor rotors). Preferred substrates include electrochemical cells, thermal management components, and structural components of EV battery packs. Exemplary articles of manufacture include (e.g., laminated or composite) architectural articles, electrical and electronic components, automotive components, abrasive articles, and medical devices. In some embodiments, articles of manufacture may include components of computers, mobile handheld electronic devices (including telephones), and touch-sensitive panels. In some embodiments, articles of manufacture may be photovoltaic modules (e.g., solar panels) including a semiconductor substrate, a cover glass substrate, and an optional back substrate, as well as adhesive layers and multilayer films. Preferred articles of manufacture include EV battery packs, including EV battery modules. Adhesives are used to bond substrates within EV battery packs, including bonding electrochemical cells to structural members, electrical busbars or leads, or thermal management components. In some embodiments, delamination can be facilitated by layering (e.g., multilayer) films for battery cell canister wrapping, bonding between battery cells, and insulation. This includes module side panel insulation, module housing insulation, and / or battery cell-to-cooling plate insulation.

[0071] Electrochemical batteries contain high levels of refined minerals, typically including cobalt, nickel, manganese, copper, aluminum, and lithium. Therefore, extending their lifespan and facilitating the recycling of EV electrochemical batteries are desirable. Sometimes, the adhesives used to bond electrochemical batteries to structural components, electrical busbars or leads, or thermal management components within a battery module or battery pack present significant challenges for disassembling the module or pack. These disassembly challenges can hinder the repair, replacement, reuse, or recycling of electrochemical batteries from EV battery modules and EV battery packs. Sometimes, electrochemical batteries cannot be separated from structural components, electrical busbars or leads, or thermal management components without damaging the battery. The articles of manufacture disclosed herein provide means for disassembling battery modules or battery packs, including removing electrochemical batteries without damage.

[0072] In advantageous embodiments, the substrate and (e.g., cured) adhesive have high heat resistance and also chemical resistance. Due to these properties, detaching the adhesive by exposure to heat or solvents is challenging. In some embodiments, at least one or both substrates are metallic or include a metallic surface layer in contact with the adhesive layer. For example, in a representative embodiment, the first substrate may be a battery cell, and the second substrate may be a cooling plate. In this embodiment, the fully spanning multilayer film may also serve as an electrical insulating layer that electrically insulates one or more battery cells from the cooling plate.

[0073] Multilayer films, along with one or more adhesive layers (e.g., tape), can be applied to the battery pack as a unit canister, the sidewalls of the battery pack, the cold plate within the battery pack, or other parts of the battery pack, and subsequently, it is desired to remove them. As an additional benefit, the multilayer film can also provide necessary electrical insulation within the battery pack to prevent unwanted electrical short circuits or arcing.

[0074] Figure 9 This is a cross-sectional view of an electrochemical cell (e.g., a 9-volt battery) bonded to a first substrate 910 and a second substrate 920 with a first adhesive layer 931 and a second adhesive layer 932. In this embodiment, the multilayer film 940 completely spans the adhesive layer. The multilayer film between the electrochemical cell and the first substrate 910 may be the same as or different from the multilayer film between the electrochemical cell and the second substrate 920. One or both multilayer films may optionally partially span the adhesive layer and / or the adhesive layer may be recessed, as previously described. The adhesively bonded article can be removed as further described in the examples. In one embodiment, by including a multilayer film spanning the adhesive layer, the average splitting strength is reduced from 251 N to 36 N, and damage to the electrochemical cell is avoided.

[0075] Figure 16 This is a cross-sectional view of a battery pack including two or more electrochemical cell units optionally bonded to a cooling plate. A first multilayer film is disposed between a first adhesive layer and a second adhesive layer. The first multilayer film, bonded to each electrochemical cell by the first adhesive layer, also surrounds the electrochemical cell to provide electrical insulation. A second multilayer film is disposed between the second adhesive layer and a third adhesive layer. The third adhesive layer is bonded to the second multilayer film and the underlying cooling plate. The adhesive layers may contain the same or different adhesive compositions. The multilayer films may be the same or different multilayer films. The second multilayer film can be used to separate the battery pack from the cooling plate. The first multilayer film can be used to separate the electrochemical cells from each other. It is also contemplated that the first or second multilayer film may be absent or may be replaced by a monolayer film.

[0076] It should be understood that "battery" articles may include additional components known in the art. For example, battery articles may include components that provide physical support, thermal management, electrical interconnection, and shock protection to the battery's electrochemical cells. Electric vehicle (EV) battery modules and battery packs are examples of battery articles.

[0077] Multilayer film

[0078] refer to Figure 10 The multilayer film 1000 includes at least two layers 1001 and 1002 with an interface between them. In some embodiments, the multilayer film includes at least 3, 4, 5, 6, 7, 8, 9, or 10 layers. For example, Figure 11 A multilayer film 1100 comprising four layers 1101, 1102, 1103, and 1104 is depicted. In some other embodiments, the multilayer film comprises multiple, or in other words, numerous layers.

[0079] For example, a multilayer film may have at least 10, 15, 20, 50, 100, 150, 200, 250, or 300 layers. In some embodiments, the multilayer film has no more than 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100, 50, 20, 15, or 10 layers. The thickness of the layers may vary depending on the number of layers. The multilayer film may include one or more layers with a thickness of at least 50 nm, 75 nm, 100 nm, 250 nm, 500 nm, 1 micrometer, 5 micrometer, 10 micrometer, 25 micrometer, or 30 micrometer.

[0080] The total thickness of the multilayer film is typically at least 5 micrometers. The total thickness of the multilayer film is typically no greater than 500 micrometers. In some embodiments, the total thickness of the multilayer film is at least 10 micrometers, 15 micrometers, 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, 45 micrometers, 50 micrometers, 55 micrometers, 60 micrometers, 65 micrometers, 70 micrometers, or 75 micrometers. In some embodiments, the total thickness of the multilayer film is no greater than 250 micrometers, 200 micrometers, 175 micrometers, 150 micrometers, 125 micrometers, 100 micrometers, 75 micrometers, or 50 micrometers. In some embodiments, the multilayer film has sufficient thickness to provide electrical insulation between the electrochemical cell (substrate) and another component (substrate) (such as a cooling plate), for example, the breakdown voltage between the substrates is greater than 1000 volts or even greater than 5000 volts.

[0081] Figure 12 depicts a multilayer film 1210 comprising multiple individual polymer layers forming a stack 1220, which may form all or part of the multilayer polymer film 1210. In the depicted embodiment, the stack 1220 consists of at least two types of polymer layers: polymer layer A, polymer layer B, and optionally polymer layer C, which are composed of different polymer compositions. These different layer types are organized into repeating groups of layers A, B, C, A, B, C, etc. The front and rear master surfaces of adjacent layers are in close contact with each other. In some embodiments, the multilayer film comprises at least four layers (e.g., A, B, C, and D).

[0082] In a typical embodiment, the multilayer film comprises at least two directly adjacent thermoplastic polymer layers (e.g., A and B). In some embodiments, the multilayer film comprises at least two (e.g., co-extruded) directly adjacent thermoplastic polymer layers. In some embodiments, the directly adjacent layers that delaminate at their interface during disassembly are (e.g., co-extruded) thermoplastic polymer layers. In some embodiments, at least 3, 4, 5, 6, 7, 8, 9, 10 or more (including all) layers of the (e.g., co-extruded) multilayer film comprise thermoplastic polymer layers that are melt-processable at temperatures in the range of 250°C to 300°C. In some embodiments, the (e.g., co-extruded) multilayer film is stretched during manufacturing. In this embodiment, at least one thermoplastic polymer layer may be oriented and may have a birefringence of at least 0.05. During disassembly of the adhesively bonded substrate, the oriented thermoplastic polymer layer typically separates from the adjacent unoriented layer when the multilayer film cracks. As used herein, “co-extrusion” refers to the process of extruding two or more materials into a single die having two or more orifices arranged such that the extrudates are combined and welded together to form a layered structure before cooling or quenching (i.e., quenching). Co-extrusion is commonly used as an aspect of other processes, such as in blown film and cast film processes.

[0083] Multilayer films typically do not contain a pressure-sensitive adhesive layer. Therefore, the thermoplastic polymer layer of a multilayer film (e.g., co-extruded) is not a pressure-sensitive adhesive. In some embodiments, the thermoplastic polymer layer of the multilayer film differs from a pressure-sensitive adhesive in that it exhibits poor peel adhesion to the substrate. For example, the 90-degree peel strength of the thermoplastic polymer layer against aluminum at 23°C and a rate of 12 inches / minute is less than 200 g / inch or 100 g / inch.

[0084] In some implementations, the thermoplastic polymer layer differs from the pressure-sensitive adhesive in that the thermoplastic polymer layer exhibits a strength greater than 3 × 10⁻⁶ at room temperature (25°C) and a frequency of 1 Hz. 6 dynes / cm 2The shear storage modulus (G') is 0.3 MPa. In some embodiments, the thermoplastic polymer layer differs from the pressure-sensitive adhesive in that the thermoplastic polymer layer has a glass transition temperature greater than 25°C.

[0085] Multilayer films can be prepared from a variety of thermoplastic polymers. The thermoplastic polymer for the multilayer film can be selected based on desired heat resistance and desired delamination strength. In typical embodiments, the multilayer film is dimensionally stable at temperatures up to 110°C or higher. In other words, the multilayer film is not a shrink film. In typical embodiments, the multilayer film, adhesive, and other optional layers disposed between the adhesively bonded substrates are free of expanding particles. Premature expansion of expanding particles can also lead to premature disassembly of the adhesively bonded substrates (e.g., battery cells and cooling plates of an EV battery). Furthermore, in some embodiments, the multilayer film, adhesive, and other optional layers disposed between the adhesively bonded substrates are not typically release layers containing fluoropolymers or other materials (e.g., silicon- and / or fluorinated) that exhibit a high forward contact angle with water (e.g., at least about 90 degrees).

[0086] In some embodiments, the multilayer film comprises a polyolefin polymer, i.e., a polymer having the general formula C n H 2n Polyolefins are polymers produced using olefins as monomers. Polyethylene is produced by polymerizing ethylene with or without one or more comonomers, polypropylene is produced by polymerizing propylene with or without one or more comonomers, and so on. Therefore, polyolefins include interpolymers such as ethylene / α-olefin copolymers, propylene / α-olefin copolymers, etc. The melting point of polyolefins is typically measured by a method as described in U.S. Patent No. 5,783,638.

[0087] Some multilayer films containing polyolefin layers are described, for example, in US 9,969,907; this patent is incorporated herein by reference. The films described therein include layers described as “adhesive layers” containing polar ethylene copolymers, such as ethylene / α,β-olefinically unsaturated carboxylic acid copolymers, ethylene vinyl acetate (“EVA”) copolymers, ethylene (meth)acrylate alkyl ester copolymers, and blends of two or more of these. It is noteworthy that such adhesive layers are generally not pressure-sensitive adhesives, as previously described.

[0088] In some embodiments, the polar ethylene copolymer is a blend of low-density polyethylene (LDPE), and the amount of LDPE is typically at least 2 wt%, 3 wt%, 4 wt%, or 5 wt% of the blend and not more than 25 wt%, 20 wt%, 15 wt%, or 10 wt%.

[0089] In some embodiments, the polar ethylene copolymer or blend typically has a melt index (MI, as measured by means of ASTM D-1238 (190°C / 2.16 kg)) of at least about 0.3 g / 10 min, 0.7 g / 10 min, 1 g / 10 min, 5 g / 10 min, or 10 g / 10 min. In some embodiments, the melt index is less than 100 g / 10 min, 75 g / 10 min, 50 g / 10 min, or 30 g / 10 min.

[0090] Polyolefin multilayer films typically include an outer layer comprising a polar ethylene copolymer or blend thereof in contact with a substrate (e.g., a metal).

[0091] Polyolefin multilayer films typically comprise one or more polyolefin layers, which generally have a higher olefin content than polar ethylene copolymers or blends. Suitable polymers include high-density polyethylene (“HDPE”, density greater than 0.93 g / cm³), polypropylene (PP), medium-density polyethylene (“MDPE”, density 0.920 g / cm³–0.930 g / cm³), and blends thereof. Propylene-based polymers include polypropylene homopolymers, copolymers of propylene with one or more other olefin monomers, blends of two or more homopolymers or copolymers, and blends of one or more homopolymers with one or more copolymers, which generally have a melting point of 125°C or higher. Polypropylene-based polymers include substantially isotactic propylene homopolymers, random propylene copolymers, and grafted or block propylene copolymers.

[0092] Suitable propylene polymer blends contain a propylene polymer in an amount of at least 30%, 35%, or 40% by weight of the blend. The amount of propylene polymer in the blend is generally no more than 80%, 70%, or 60% by weight of the blend.

[0093] Propylene copolymers typically contain at least 85 mol%, 87 mol%, or 90 mol% of propylene-derived units. Propylene copolymers typically contain at least one α-olefin with no more than 20, 12, or 8 carbon atoms. The α-olefin is typically a C3-20 linear, branched, or cyclic α-olefin. In some embodiments, the MFR (measured in dg / min at 230°C / 2.16 kg) of the propylene polymer is at least 0.5 dg / min, 1 dg / min, 1.5 dg / min, 2 dg / min, or 2.5 dg / min, and typically no more than 25 dg / min, 20 dg / min, or 15 dg / min.

[0094] The layer containing the polar ethylene copolymer can be peeled off from the polypropylene layer. The interlayer peel strength described in US9969907 is from about 5 lbf / inch width to 15 lbf / inch width. However, depending on the choice of adjacent adhesive layers as described herein, the splitting strength can be significantly greater.

[0095] In some embodiments, the multilayer polyolefin film comprises two layers: a first layer comprising a polar ethylene copolymer or a blend thereof, and a second layer comprising a propylene-based polymer. In another embodiment, the multilayer polyolefin film comprises at least three layers: at least two layers of a polar ethylene copolymer or a blend thereof disposed on two main surfaces of a propylene-based polymer layer, or at least two layers of a propylene-based polymer layer disposed on two main surfaces of a layer comprising a polar ethylene copolymer or a blend thereof. Layers containing polar ethylene copolymers may exhibit better adhesion to adhesive layers.

[0096] The multilayer film may further optionally contain a density of less than about 0.92 g / cm³. 3 One or more layers of vinyl polymers. These include high-pressure, free radical low-density polyethylene (LDPE), heterogeneous linear low-density polyethylene (LLDPE), ultra-low-density polyethylene (ULDPE), and very low-density polyethylene (VLDPE), as well as multi-reactor olefin polymers (“in-reactor” blends of Ziegler-Natta PE and metallocene PE). When present, such layers may exist between a propylene-based polymer layer and a layer comprising a polar ethylene copolymer or a blend thereof.

[0097] When high heat resistance is required, multilayer films typically contain thermoplastic polymers with high Tg and / or melting temperatures, as previously described. Representative thermoplastic polymers include polyester polymers, including copolyesters, acrylic polymers (e.g., polymethyl methacrylate and its copolymers), polyurethane polymers, polyether polymers, and polyamides, including silicone polyethylene glycol amide.

[0098] In some embodiments, the multilayer film comprises a thermoplastic polymer, including polymethyl methacrylate (PMMA) such as those available under the trade names CP71 and CP80 from Ineos Acrylics, Inc., Wilmington, DE, or a homopolymer of polyethyl methacrylate (PEMA) having a lower glass transition temperature than PMMA. Additional thermoplastic polymers for multilayer films include copolymers of PMMA (coPMMA), such as coPMMA prepared from 75% by weight of methyl methacrylate (MMA) monomer and 25% by weight of ethyl acrylate (EA) monomer (available under the trade name Perspex CP63 from INEOS Acrylic Acids); coPMMA prepared from MMA comonomer units and n-butyl methacrylate (nBMA) comonomer units; or blends of PMMA and poly(vinylidene fluoride) (PVDF), such as Solvay Polymers, Inc., Houston, TX, available under the trade name Solvay 1008.

[0099] In some implementations, such thermoplastic polymers typically contain aromatic or alicyclic moieties.

[0100] In some embodiments, the multilayer film comprises a polyester polymer (e.g., aromatic) polyester (homogeneous and copolymeric), such as polyethylene terephthalate (“PET”), polybutylene terephthalate, polyhexylene terephthalate, polybutylene naphthalate, polyhexylene naphthalate, polyethylene naphthalate (“PEN”), copolymers or blends thereof, or copolyesters thereof, such as 90 / 10 coPEN, or amorphous poly(ethylene terephthalate) copolymers (also referred to herein as PETG). The polyester polymer typically has a molecular weight of at least 10,000 Daltons, 20,000 Daltons, or 30,000 Daltons, and typically no greater than 50,000 Daltons. In some embodiments, the layers that delaminate at the interface during disassembly are (e.g., co-extruded) thermoplastic polyester layers. In some embodiments, at least 3, 4, 5, 6, 7, 8, 9, 10 or more (including all) layers of a multilayer film (e.g., co-extruded) comprises a thermoplastic polyester layer.

[0101] In some embodiments, the multilayer film can be characterized as a multilayer optical film (MOF). Multilayer optical films, i.e., films that provide desired transmission and / or reflection properties at least in part through an arrangement of microlayers with different refractive indices, are known. Multilayer optical films can be prepared by co-extruding alternating thermoplastic polymer layers. See, for example, U.S. Patents 3,610,729 (Rogers), 4,446,305 (Rogers et al.), 4,540,623 (Im et al.), 5,448,404 (Schrenk et al.), and 5,882,774 (Jonza et al.).

[0102] Multilayer optical films consist of individual microlayers with different refractive index characteristics, such that some light is reflected at the interfaces between adjacent microlayers. The microlayers are thin enough that the light reflected at multiple interfaces undergoes constructive or destructive interference to impart the desired reflection or transmission properties to the multilayer optical film. For multilayer optical films designed to reflect ultraviolet, visible, or near-infrared wavelengths of light, each microlayer typically has a refractive index of less than approximately 1. The optical thickness (physical thickness multiplied by refractive index) is m. However, in this invention, the primary concern is the difference in crystallinity or birefringence that contributes to high splitting strength, rather than optical properties. Thicker layers may also be included, such as a surface layer located at the outer surface of the multilayer optical film or a protective boundary layer (PBL) disposed within the multilayer optical film to separate intrinsic groups (referred to herein as "layer groups") of microlayers.

[0103] In some implementations, the MOF film can be characterized as a reflective polarizer, wherein at least some optical layers are formed using a birefringent polymer, wherein the polymer's refractive index has different values ​​along the polymer's orthogonal Cartesian axes. Typically, the birefringent polymer microlayers have orthogonal Cartesian axes defined by the normal (z-axis) of the layer plane, where the x-axis and y-axis lie in the layer plane. Birefringent polymers can also be used in non-polarizing applications.

[0104] In some cases, the microlayers have a thickness and refractive index value corresponding to a ¼ wavelength stack, i.e., arranged in optical repeating units or cells, each optical repeating unit or cell having two adjacent microlayers of equal optical thickness (f ratio = 50%). Such optical repeating units effectively reflect light through constructive interference, and the wavelength of the reflected light is... This is twice the overall optical thickness of the optical repeating unit. Other layer arrangements are also known, such as multilayer optical films with a double microlayer optical repeating unit having an f-ratio different from 50%, or films where the optical repeating unit comprises more than two microlayers. These optical repeating unit designs can be configured to reduce or increase certain higher-order reflections. See, for example, U.S. Patent Nos. 5,360,659 (Arends et al.) and 5,103,337 (Schrenk et al.). A thickness gradient along the film thickness axis (e.g., the z-axis) can be used to provide a broadened reflection band, such as a reflection band that extends across the entire visible region and into the near-infrared region, such that the microlayer stack continues to reflect across the entire visible spectrum as the band shifts at an oblique angle of incidence to a shorter wavelength. Sharpening band edges (i.e., the wavelength transition between high reflectivity and high transmittance) by adjusting the thickness gradient is discussed in U.S. Patent No. 6,157,490 (Wheatley et al.).

[0105] In an exemplary embodiment, the microlayers are arranged as optical repeating units, each having an optical thickness, the optical repeating units being arranged to provide a substantially monotonically or smoothly increasing optical thickness distribution. At least some of the N microlayers comprise polyethylene naphthalate or a copolymer thereof, and N is 350 or less, or 300 or less, or in the range of 250 to 350, or in the range of 275 to 375. Alternatively, at least some of the N microlayers comprise polyethylene terephthalate or a copolymer thereof, and N is 800 or less, or 650 or less, or in the range of 300 to 650, or in the range of 500 to 650.

[0106] The reflection and transmission properties of multilayer optical films are functions of the refractive index of the corresponding microlayers, as well as the thickness and thickness distribution of the microlayers. Each microlayer (at least at a local location in the film) can transmit light through an in-plane refractive index n. x n y and the refractive index n associated with the thickness axis of the film. z These refractive indices represent the refractive index of the material under discussion for light polarized along mutually orthogonal x, y, and z axes. These indices can be labeled n1x, n1y, n1z for the first layer and n2x, n2y, n2z for the second layer, with corresponding layer-to-layer differences of n1x, n2y, and n2z. n x , n y , n z For ease of illustration in this patent application, unless otherwise specified, it is assumed that the x-axis, y-axis, and z-axis are local Cartesian coordinates applicable to any point of interest on the multilayer optical film, wherein the microlayer extends parallel to the xy plane, and wherein the x-axis is oriented in the film plane to maximize n x The value of. Therefore, n y The value can be equal to or less than (but not greater than) . n x The value of the quantity. Furthermore, by requiring... n x The non-negative value is used to determine the calculation of the difference. n x , n y , n z The selection of the starting material layer. In other words, the refractive index difference between the two layers forming the interface is... n j =n 1j –n 2j Where j = x, y, or z, and where layer labels 1 and 2 are chosen such that n 1x n 2x ,Right now n x 0.

[0107] In practice, the refractive index is controlled through careful material selection and processing conditions. Such multilayer films are prepared by co-extruding a large number (e.g., tens or hundreds) of alternating layers of two polymers, A and B, typically followed by passing the multilayer extrudate through one or more multiplier dies, and then stretching or otherwise oriented the extrudate to form the final film. The resulting film typically consists of hundreds of individual microlayers, the thickness and refractive index of which are adjusted to provide one or more reflective bands in a desired spectral region (e.g., the visible or near-infrared region). To achieve high reflectivity with an appropriate number of layers, adjacent microlayers typically exhibit a difference in refractive index for light polarized along the x-axis (…). n x The refractive index difference should be at least 0.05. If high reflectivity for two orthogonal polarizations is desired, adjacent microlayers can also be made to exhibit a refractive index difference of at least 0.05 for light polarized along the y-axis. n y ).

[0108] In an exemplary embodiment, the reflective polarizer has a blocking axis (x) and a transmitting axis (y), as well as opposing first and second principal surfaces exposed to air and thus exhibiting minimal Brewster angular reflectivity, and these principal surfaces are configured to be perpendicular to the z-axis. A stack of N microlayers is disposed between the principal surfaces and arranged in pairs of adjacent microlayers, which exhibit refractive index differences along the x-axis, y-axis, and z-axis, respectively. nx , n y and n z ,in n x > n y >0> n z .

[0109] U.S. Patent No. 9,110,245, incorporated herein by reference, describes modeled reflection curves illustrating a technique for increasing the reflectivity along the transmission axis by increasing the reflectivity of microlayers along the y-axis. Each curve represents the calculated reflectivity of a specific multilayer reflective polarizer construction for p-polarized light incident on the yz plane, the reflectivity depending on the angle of incidence in air. Each modeled polarizer construction assumes a total of N microlayers arranged within a single stack, with the outer surfaces of the first and last microlayers exposed to air. The N microlayers are arranged in an alternating configuration of first and second polymers, wherein adjacent pairs of first and second polymers form optical repeating units with an f-ratio of 50%. The optical repeating units have a linear optical thickness distribution ranging from 200 nm (corresponding to the peak vertical incidence reflection at 400 nm) for the first pair of layers to 462 nm (corresponding to the peak vertical incidence reflection at 925 nm) for the last pair of layers. Some modeled (e.g., reflective polarizer) MOF constructions suitable for this invention have the following additional characteristics:

[0110] The refractive index in the x-direction has no effect on modeling and is therefore not listed. The birefringences n1y and n1z used are representative birefringences of 90 / 10 coPEN at approximately 145°C, a stretch ratio of approximately 5:1, and a strain rate of approximately 5 m / min. The isotropic refractive index n2 used is the representative isotropic refractive index of coPEN 55 / 45 (MOF1), a blend of 46% 90 / 10 coPEN and 54% PETG (for MOF2), and PETG (for MOF3 and MOF4).

[0111] Various other multilayer optical films are known in the art. See, for example, US8182924 and US9046656, which are incorporated herein by reference. Various multilayer films including optical films are commercially available from 3M Company (3M). In some embodiments, the multilayer film may comprise a polyacrylate surface layer, such as described in US8182924, which may exhibit better adhesion to adhesives comprising (meth)acrylate monomers and / or acrylic polymers.

[0112] While the illustrated multilayer film, for example, has multiple layers with specific refractive indices and differences to achieve certain optical effects, for the purposes of this invention, the multilayer film may contain only two layers, or alternating layers A, B, and optionally C, much less than 275, as previously described. However, a larger number of layers can be beneficial for energy absorption or provide high interlayer delamination strength, which may be important for EV battery packs, especially in the event of a vehicle collision.

[0113] As demonstrated in the upcoming examples, multilayer (e.g., optical) films containing thermoplastic (e.g., aromatic) polyester layers can provide reduced splitting strength and retained lap shear strength relative to the control.

[0114] In some other embodiments, for articles in which moderate heat resistance (e.g., greater than that of polyolefins but less than that of (e.g., aromatic) polyesters) is desired, the multilayer film may comprise two or more layers, wherein at least one layer comprises a thermoplastic polymer with high heat resistance, such as polyester, and at least one layer comprises a polyolefin, a styrene block copolymer, or a mixture thereof. In some embodiments, the multilayer film 1100 includes an inner layer comprising a polyolefin, a styrene block copolymer, or a mixture thereof (e.g., Figure 11 The inner layer (1102 or 1103) is disposed between the outer layers (1100 and 1104) which contain a thermoplastic polymer (such as polyester) with high heat resistance.

[0115] Suitable polyester and polyolefin materials have been previously described. Various styrene block copolymers are known in the art. In some embodiments, the styrene block copolymer is a linear triblock copolymer comprising polystyrene blocks and polyolefin blocks, such as ethylene / butene. In some embodiments, the block copolymer has a polystyrene content in the range of about 10 mol% to 15 mol%. The block copolymer may have a melt flow index in the same range as polyolefins as previously described. In some embodiments, the melt flow (230°C / 216 g, ASTM D1238) is in the range of 2 g / 10 min to 5 g / 10 min. In some embodiments, the block copolymer has a tensile strength in the range of about 750 psi to 3000 psi (ASTM D412). In some embodiments, the block copolymer has a Shore hardness in the range of 25 to 50 (ASTM D2240, Shore A (10 seconds)). In some embodiments, the block copolymer has an elongation in the range of 300% to 1000% (ASTM D412). The block copolymer may also contain polystyrene / polyolefin (e.g., ethylene / butene) diblocks.

[0116] In some embodiments, the block copolymer comprises a blend of a polyolefin (e.g., polypropylene) and a styrene block copolymer (e.g., SEPS) in a weight ratio ranging from 9:1 to 1:9. In some embodiments, the weight ratio is at least 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, or 8:1.

[0117] This type of multilayer film is described in U.S. Patent No. 10,710,343, which is incorporated herein by reference.

[0118] Multilayer membranes may also contain additive inorganic fillers, such as talc (including epoxy-coated talc), colorants, flame retardants (halogenated and non-halogenated), and flame retardant synergists, such as Sb₂O₃. In some embodiments, variations in the amount of inorganic fillers within the layers of the multilayer membrane can contribute to interlayer delamination strength. The term "within" refers to layers below the first primary surface of the membrane and above the second primary surface. It is important to note that layers disposed on the primary surfaces of the membrane (such as coatings) are not layers within the multilayer membrane.

[0119] Multilayer films typically comprise at least two layers with different crystallinities. In a typical embodiment, at least one layer of the multilayer film contains a crystalline polymer, including a semi-crystalline polymer, and at least one adjacent layer is significantly less crystalline or amorphous. Differences in crystallinity or birefringence contribute to the interlayer delamination strength of the multilayer film.

[0120] As described in the interlayer peel strength test method, a multilayer film individually possesses interlayer peel strength, which is the load per unit width when the layers of the multilayer film are peeled apart at a 90-degree orientation. Interlayer peel strength is a property of the multilayer film alone, describing the delamination of polymer layers that are not directly adjacent to the pressure-sensitive adhesive. This test method quantifies the delamination strength of the multilayer film at its internal interfaces at 23°C. In some embodiments, the multilayer film delaminates at interfaces having an interlayer peel strength of at least 10 g / in, at least 50 g / in, at least 100 g / in, at least 200 g / in, or at least 500 g / in at 23°C. In some embodiments, the multilayer film delaminates at interfaces having an interlayer peel strength of no more than 2500 g / in, 2000 g / in, 1500 g / in, 1000 g / in, 500 g / in, 200 g / in, or 100 g / in at 23°C. Multilayer films with high interlayer peel strength are known; some of these are described in previously cited U.S. Patent No. 10,710,343.

[0121] The adhesive articles disclosed herein include (e.g., multilayer) films at least partially within an adhesive layer between two substrates. The (e.g., multilayer) films contribute to the strength of the adhesive articles (e.g., splitting strength and lap shear strength). While the interlaminar peel strength of the multilayer film (a property of the film alone) contributes to the strength of the adhesively bonded articles, the splitting strength of the articles is not solely determined by the interlaminar peel strength of the film. The delamination mechanism during 90-degree peeling (e.g., in film interlaminar peel strength testing methods) differs from, for example, the delamination mechanism during splitting or lap shearing. Furthermore, other factors (including, for example, the Young's modulus of the adhesive, the indentation of the adhesive layer, and whether the adhesive layer partially or completely spans the adhesive layer) are found to be variables relative to the splitting strength of the adhesively bonded articles. For example, when one or both substrates are rigid, the splitting strength of the adhesive article can be significantly greater than the interlaminar peel strength of the multilayer film.

[0122] Various interlayer peel strengths can be obtained by adjusting the crystal content of the crystalline layer. For example, when the crystalline layer contains a crystalline polyolefin (e.g., polypropylene) and a block copolymer (e.g., SEPS) in a weight ratio of 9:1, the interlayer peel strength can be about 25 g / in, and the peel strength increases as the amount of crystalline polyolefin decreases and the amount of block copolymer increases. When the crystalline layer contains a crystalline polyolefin and block copolymer in a weight ratio of 4:6, the interlayer peel strength can be about 250 g / in. Higher interlayer peel strengths can be obtained by further reducing the amount of crystalline polyolefin and increasing the amount of block copolymer. However, when the crystal content is too low, the interlayer peel strength may exceed the film strength. In this embodiment, the multilayer film can tear in a direction parallel to the thickness (z-direction), rather than splitting or in other words delaminating in a direction orthogonal to the thickness.

[0123] In some embodiments, the bonded article may comprise a multilayer film having the same interlayer delamination strength between the layers. When the layers are thin, the splitting strength can be the same regardless of the actual location of the delamination.

[0124] In some embodiments, the adhesive article may comprise a multilayer film having at least two different interlayer delamination strengths. For a multilayer film having at least two different interlayer delamination strengths, it means that the film comprises at least three layers, and therefore has at least two internal interfaces between directly adjacent pairs of layers, and the interlayer delamination strengths between at least two pairs of directly adjacent layers are different. In other embodiments, the adhesive article may comprise at least two multilayer films with different interlayer delamination strengths.

[0125] By using different materials in the multilayer film, one or more multilayer films can have different first layer strengths and second layer strengths. The first layer strength can differ from the second layer strength by, for example, at least 2, 3, 4, 5, 6, 7, 8, 9, or 10 times.

[0126] In some implementations, (e.g., multilayer) membranes include tabs, markers, or combinations thereof that indicate one or more layer locations.

[0127] To facilitate the removal of portions of the layers (i.e., layer groups) in a single, sequential manner and to ensure delamination occurs at the interfaces between the layer groups, multilayer films can be fabricated with hemispherical flap-like features of varying depths near the film edges, such as... Figure 12A and Figure 12B These features provide proximity to the desired layered surface and can therefore be called proximity tabs.

[0128] Proximity tabs can be formed in any suitable manner. In one embodiment, recessed proximity tabs can be provided by laser radiation to cut and subdivide polymer multilayer films without any significant delamination at the laser-cut edge line, as described in WO 2012 / 092478 (Wu et al.). The laser radiation is selected to have a wavelength at which at least some of the film material is significantly absorbed, such that the absorbed electromagnetic radiation can effectively evaporate or ablate the film mass along the cut line. The laser radiation is also shaped with a suitable focusing optics system and controlled to a suitable power level to achieve evaporation along a narrow cut line. The laser radiation can be rapidly scanned across the entire workpiece according to pre-programmed instructions and rapidly switched on and off, allowing it to follow cut lines of arbitrary shapes. Alternatively, mechanical blades and other cutting devices can be used instead of laser radiation to form tab-like features.

[0129] In some implementations, (e.g., multilayer) films include one or more markings for each layer location. The markings can be labels, logos, alphanumeric characters, or other symbols, and can be different colors. Such markings can be placed in recessed locations near the tabs, such as... Figure 12A and Figure 12B As depicted. Alternatively, such markings may be set on unbonded multilayer membrane tabs.

[0130] In one embodiment, marking 1216 is a number visible to the user in the area near tab 1215 and serves as a general indication of how many layers remain in the stack and on the workpiece. For example, when the foremost layer group 1222 is delaminated and removed, marking 1216 in the form of "6" will be removed along with group 1222, so that the user can only see markings 1216 in the forms of "1", "2", "3", "4", and "5". Marking 1216 is shown as shallow holes or recesses in polymer layer A, but they can be utilized with alternative designs.

[0131] In another embodiment, marking 1217 represents holes of varying depths. These holes may all open at the exposed surface of the foremost layer and terminate at different layers. The shallowest hole terminates at the foremost layer group 1222, the next deepest hole terminates at the next layer group 1224, the next deepest hole terminates at the next layer group 1226, and so on (e.g., 1228, 1230). These holes are shown as simple circular holes and do not overlap, and are spaced apart from each other in a straight line along the edge of the stack 1220, but other designs may also be used. These markings 1217 also provide the user with an indication of how many layer groups remain in the stack and on the workpiece. For example, in Figure 12A In the plan view, six markings 1217 are visible, but after peeling off the outermost layer group 1222, only five markings 1217 will remain, and after peeling off layer group 1224, only four markings 1217 will remain, and so on. Although tabs are depicted along the same edge of the multilayer film, the tabs may be at different (e.g., opposite) edges. When the article comprises two or more multilayer films, each multilayer film may have one or more tabs positioned along the same or different edges of the multilayer film.

[0132] Methods for manufacturing bonded articles

[0133] Adhesive-bonded articles can be manufactured by any suitable method. In some embodiments, an adhesive-bonded article is prepared by applying a first adhesive layer to a first substrate; applying a second adhesive layer to a second substrate; and bringing the first adhesive layer and the second adhesive layer into contact such that a multilayer film is at least partially disposed between the first adhesive layer and the second adhesive layer.

[0134] In some embodiments, the multilayer film is at least partially applied to the surface of a first adhesive layer, and then the multilayer film (and the first adhesive layer when the multilayer film partially crosses the adhesive layer) is brought into contact with a second adhesive layer, or vice versa. In this embodiment, the adhesive may be a curable liquid adhesive or a partially cured adhesive layer of transfer tape. The adhesive layer can be applied using an adhesive dispenser (e.g., a robot). The multilayer film may be supplied in rolls, which are cut to the desired size before or after bonding.

[0135] In other embodiments, at least one adhesive layer (e.g., a first adhesive layer or a second adhesive layer) is pre-applied as a single-sided tape to one main surface of the multilayer film. The adhesive layer of the single-sided tape contacts the first or second substrate. Then, a curable liquid adhesive or a partially cured adhesive layer of transfer tape is applied to the other main surface of the multilayer film or the surface of another substrate. The assembled layers are then cured sequentially or simultaneously.

[0136] In another embodiment, an adhesive layer (e.g., a first or second) is pre-applied as a double-sided tape to both main surfaces of the multilayer film. When the adhesive layer is a structural adhesive layer, it typically contains a curable composition that may initially be characterized as a pressure-sensitive adhesive, but which, given its high Tg, high modulus, and lack of peel adhesion properties, ceases to be a pressure-sensitive adhesive after curing, as previously described.

[0137] Liquid curable adhesives or partially cured adhesive layers can be heat-cured or cured by exposure to photochemical radiation (e.g., ultraviolet or electron beam radiation).

[0138] Therefore, adhesive tape articles comprising one or more adhesive layers of various types and combinations as described herein are also described.

[0139] The film to be adhesively bonded (e.g., multilayer) and the substrate can be subjected to conventional surface treatments to improve adhesion. Surface treatments include, for example, exposure to ozone, exposure to flame, exposure to high-voltage electric shock, treatment with ionizing radiation, and other chemical or physical oxidation treatments. Chemical surface treatments include primers. Examples of suitable primers include chlorinated polyolefins, polyamides, and modified polymers disclosed in U.S. Patents 5,677,376, 5,623,010 and those disclosed in WO 98 / 15601 and WO 99 / 03907, as well as other modified acrylic polymers. In one embodiment, the primer is an organic solvent-based primer comprising an acrylate polymer, a chlorinated polyolefin, and an epoxy resin, which can be used as a "3M" primer. ™ "Primer 94" was purchased from 3M Company. Mechanical grinding or other forms of treatment used to increase surface area can also be used to improve adhesion.

[0140] Adhesive layer

[0141] The adhesive layer may include a variety of adhesives, depending on the desired heat resistance properties of the adhesively bonded article and the method of manufacturing such article.

[0142] In some embodiments, such as for articles where low heat resistance is suitable, the adhesive may include a pressure-sensitive adhesive. The pressure-sensitive adhesive has properties including: a Tg of less than 25°C (including less than 0°C, -20°C, -40°C, -60°C), and less than 3 × 10⁻⁶ at room temperature (25°C) and a frequency of 1 Hz. 6 dynes / cm 2 Shear storage modulus (G') of 0.3 MPa, and sufficient adhesion (e.g., at 23°C and a rate of 12 inches / min, the thermoplastic polymer layer has a 90-degree peel strength of at least 100 g / in and 200 g / in against aluminum).

[0143] Pressure-sensitive adhesives are typically classified based on their polymer composition, such as acrylic adhesives, polyurethane adhesives, silicone adhesives, natural and synthetic rubber adhesives, polyolefin adhesives, block copolymer adhesives, etc. When using non-curable pressure-sensitive adhesives, the heat resistance of the bonded products and tapes may be limited by the heat resistance (Tg) of the pressure-sensitive adhesive.

[0144] In other embodiments where higher heat resistance and / or greater bond strength are desired, the adhesive is typically a curable structural adhesive, including semi-structural adhesives. In this embodiment, the adhesive layer is not a pressure-sensitive adhesive (as previously described with respect to multilayer films). However, in some embodiments, the structural adhesive may initially be pressure-sensitive but is not pressure-sensitive after curing.

[0145] The Young's modulus of the (cured) adhesive is a variable that affects the splitting strength and lap shear strength of articles having multiple films within the adhesive layer. In some embodiments, the Young's modulus of the (cured) adhesive is less than 2000 MPa, 1500 MPa, 1000 MPa, 500 MPa, 250 MPa, 100 MPa, 50 MPa, or 25 MPa. In some embodiments, the Young's modulus of the (cured) adhesive is at least 0.5 MPa, 1 MPa, 2 MPa, 3 MPa, 5 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 50 MPa, 100 MPa, 250 MPa, 500 MPa, 750 MPa, 1000 MPa, or 1500 MPa.

[0146] In some embodiments, a multilayer film having an interlayer delamination strength greater than 50 g / in is used with a (cured) adhesive, wherein the (cured) adhesive has a Young's modulus of less than 1700 MPa. In other embodiments, a multilayer film having an interlayer delamination strength greater than 100 g / in is used with a (cured) adhesive, wherein the (cured) adhesive has a Young's modulus of less than 1000 MPa. In other embodiments, a multilayer film having an interlayer delamination strength greater than 200 g / in is used with a (cured) adhesive, wherein the (cured) adhesive has a Young's modulus of less than 500 MPa.

[0147] The (cured) adhesive can be selected from a variety of one-part and two-part structural adhesives already described in the art. For example, suitable polyurethane structural adhesives comprising a polymeric polyol component and an isocyanate component are known. See, for example, US5162481, US5606003, and US8410213, and EP-627451, which are incorporated herein by reference. Representative two-part polyurethane compositions are available from 3M... ™ Scotch-Weld ™ The multi-material composite polyurethane adhesive DP 6310NS was commercially available from 3M.

[0148] In some embodiments, one or more adhesive layers comprise a curable adhesive comprising a (meth)acrylate portion, a polyurethane portion, an epoxy portion, or a combination thereof. The curable adhesive is cured. In some embodiments, the adhesive also comprises an elastic component (e.g., a toughening agent), such as synthetic nitrile rubber or a styrene block copolymer.

[0149] In some embodiments, the (curable) adhesive comprises one or more epoxy resins. The epoxy resin or epoxide is an organic compound having at least one ethylene oxide ring capable of ring-opening polymerization, i.e., an average epoxy functionality greater than one, and preferably at least two. The epoxide can be monomeric or polymeric, and can be aliphatic, alicyclic, heterocyclic, aromatic, hydrogenated, or mixtures thereof. Preferred epoxides contain more than 1.5 epoxy groups per molecule, and preferably at least 2 epoxy groups per molecule. Available materials typically have a weight-average molecular weight of about 150 to about 10,000, and more typically about 180 to about 1,000. The molecular weight of the epoxy resin is generally selected to provide the desired properties of the cured adhesive. Suitable epoxy resins include linear polymeric epoxides having terminal epoxy groups (e.g., polyalkoxydiol diglycidyl ether), polymeric epoxides having skeletal epoxy groups (e.g., polybutadiene polyepoxy), and polymeric epoxides having epoxy side groups (e.g., glycidyl methacrylate polymers or copolymers), and mixtures thereof. Epoxide-containing materials include compounds having the following general formula:

[0150] Wherein R1 is an alkyl, alkyl ether, or aryl group, and n is 1 to 6.

[0151] Epoxy resins include aromatic glycidyl ethers (such as aromatic glycidyl ethers prepared by reacting polyphenols with an excess of epichlorohydrin), alicyclic glycidyl ethers, hydrogenated glycidyl ethers, and mixtures thereof. Such polyphenols may include resorcinol, catechol, hydroquinone, and polyphenols such as p,p'-dihydroxydibenzyl sulfone, p,p'-dihydroxydiphenyl sulfone, p,p'-dihydroxyphenyl sulfone, p,p'-dihydroxybenzophenone, 2,2'-dihydroxy-1,1-dinaphthylmethane, and 2,2'-dihydroxydiphenylmethane, dihydroxydiphenyldimethylmethane, dihydroxydiphenylethylmethylmethane, dihydroxydiphenylmethylpropylmethane, dihydroxydiphenylethylphenylmethane, dihydroxydiphenylpropylphenylmethane, dihydroxydiphenylbutylphenylmethane, dihydroxydiphenyltolylethane, dihydroxydiphenyltolylmethylmethane, dihydroxydiphenyldicyclohexylmethane, and the 2,2', 2,3', 2,4', 3,3', 3,4', and 4,4' isomers of dihydroxydiphenylcyclohexane.

[0152] Also available are polyphenol-formaldehyde condensation products and glycidyl ethers containing epoxy or hydroxyl groups as reactive groups only. Available curable epoxy resins are also described in various publications, including, for example, the *Handbook of Epoxy Resins* by Lee and Nevill, published by McGraw-Hill Book Co., New York, in 1967. Handbook of Epoxy Resins ) and the Encyclopedia of Polymer Science and Technology ( Encyclopedia of Polymer Science and Technology Volume 6, page 322 (1986).

[0153] Examples of commercially available epoxides include diglycidyl ethers of bisphenol A (e.g., products available from Momentive Specialty Chemicals, Inc. under the trade names EPON828, EPON 1001, EPON 1004, EPON 1007, EPON 2004, EPON 1510, and EPON 1310, and products available from Dow Chemical Co. under the trade names DER331, DER332, DER334, and DEN439); diglycidyl ethers of bisphenol F (e.g., products available from Huntsman Corporation under the trade name ARALDITE GY 281); silicone resins containing diglycidyl epoxy functional groups; flame-retardant epoxy resins (e.g., products available from Dow Chemical Company under the trade name DER 560 (a brominated bisphenol type epoxy resin); and 1,4-butanediol diglycidyl ether.

[0154] In some embodiments, the adhesive comprises an epoxy resin having an epoxy equivalent (EEW) of at least 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1000, or an EEW range having a minimum or maximum of such stated values. In some embodiments, the adhesive comprises an epoxy resin having an epoxy equivalent (EEW) of at least 1500, 2000, 2500, 3000, 3500, 4000, 4500, or 5000, or an EEW range having a minimum or maximum of such stated values. Various combinations of epoxy resins with different epoxy equivalent ranges can be used.

[0155] In a typical embodiment, the adhesive composition comprises one or more aromatic epoxy resins, such as aromatic epoxy resins containing a bisphenol moiety. In other embodiments, a mixture of aromatic and non-aromatic epoxy resins is used.

[0156] When the adhesive composition also contains (meth)acrylate monomers, the adhesive composition typically contains at least 25%, 30%, 35%, or 40% epoxy resin, based on the total amount of (meth)acrylate monomers and epoxy resin. In some embodiments, the adhesive composition contains no more than 50% epoxy resin. However, when the adhesive composition does not contain (meth)acrylate monomers, the amount of epoxy resin can be greater.

[0157] Epoxy adhesive compositions typically contain hydroxyl-containing components that do not contain (meth)acrylate groups. The hydroxyl-containing compound acts as a chain transfer agent when the epoxy groups react according to a cationic mechanism. When hydroxyl-containing components are present, their amounts typically range from 5% to 15% by weight of the adhesive composition.

[0158] In some embodiments, the hydroxyl-containing compound is a polyol, such as a polyether polyol or a polyester polyol. The polyether polyol includes, but is not limited to, one or more of the group consisting of polyether triols and polyether diols. Various polyether polyols are known to typically have a molecular weight of at least 500 g / mol, 1000 g / mol, or 1500 g / mol or 2000 g / mol. In some embodiments, the polyether polyol has a molecular weight not greater than 5000 g / mol, 4000 g / mol or 3000 g / mol.

[0159] In some embodiments, the epoxy adhesive composition further comprises a polymer toughening agent, such as synthetic rubber, styrene block copolymer, and core-shell polymer, as described in US 4,704,331, which is incorporated herein by reference. In other embodiments, the epoxy resin may be combined with a (meth)acrylate monomer that can be partially polymerized.

[0160] In some embodiments, the adhesive comprises one or more (meth)acrylate monomers. The (meth)acrylate monomers can be characterized as low or high Tg monofunctional (meth)acrylate alkyl monomers and (e.g., acidic and non-acidic) polar monomers. The Tg of the homopolymers of various monomers is known and reported in various handbooks and by the suppliers of the various monomers.

[0161] Curable structural adhesive compositions typically contain high concentrations of one or more (e.g., nonpolar, non-acidic) high-Tg monofunctional alkyl (meth)acrylate monomers, i.e., (meth)acrylate monomers with a Tg of at least 25°C, 30°C, 35°C, 40°C, 45°C, or 50°C when reacting to form a homopolymer. In some embodiments, the Tg of the homopolymer of this high-Tg monomer is at least 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, or 90°C. In some embodiments, the Tg of the high-Tg monomer is not greater than 125°C or 100°C. In some embodiments, the high-Tg monomer contains cyclic groups.

[0162] Representative high Tg monomers include tert-butyl acrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, stearyl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, isoborneol acrylate, isoborneol methacrylate, norborneol acrylate, benzyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, cyclohexyl acrylate, tert-butylcyclohexyl acrylate, and propyl methacrylate or combinations thereof.

[0163] In some embodiments, such as when the adhesive composition also contains an epoxy resin, the curable adhesive composition contains at least 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt% of high Tg monofunctional (meth)acryloyl monomers, based on the total amount of monofunctional (meth)acryloyl monomers (e.g., their polymeric units). In some embodiments, the adhesive composition contains no more than 50 wt%, 45 wt%, 40 wt%, 35 wt%, 30 wt%, 25 wt%, or 20 wt% of high Tg monofunctional (meth)acryloyl monomers. When the adhesive composition does not contain an epoxy resin, the amount of high Tg monofunctional (meth)acryloyl monomers can be greater.

[0164] In some embodiments, the adhesive composition comprises one or more low-Tg (meth)acrylate monomers (e.g., their polymeric units), i.e., (meth)acrylate monomers whose Tg does not exceed 0°C when reacting to form a homopolymer. In some embodiments, the Tg of the low-Tg monomer does not exceed -10°C, -20°C, -30°C, -40°C, -50°C, or -60°C. The Tg of the homopolymer of the low-Tg monomer is typically at least -80°C, -70°C, -60°C, or -50°C.

[0165] This low-Tg monomer is typically a monofunctional (meth)acrylate alkyl monomer having the following formula:

[0166] Where R 1 It is hydrogen or methyl, and R 8 It is an alkyl group having 4 to 22 carbons. The alkyl group is usually straight-chain or branched. The term "monofunctional" refers to a monomer having a single (meth)acrylate group.

[0167] Exemplary low-Tg monomers monofunctional (meth)acrylate alkyl ester monomers include, for example, ethyl acrylate, n-propyl acrylate, n-butyl acrylate (BA), isobutyl acrylate, tert-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, 2-methylbutyl acrylate, 2-ethylhexyl acrylate (2EHA), 4-methyl-2-pentyl acrylate, n-octyl acrylate, 2-octyl acrylate, isooctyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, lauryl acrylate, isotriadecyl acrylate, octadecyl acrylate, and dodecyl acrylate.

[0168] In a typical embodiment, the adhesive composition comprises a low-Tg monofunctional alkyl monomer (e.g., its polymeric unit) having an alkyl group containing 4 to 12 carbon atoms. Exemplary monomers include, but are not limited to, butyl acrylate, 2-ethylhexyl (meth)acrylate, isooctyl acrylate, n-octyl (meth)acrylate, 2-octyl (meth)acrylate, isodecanyl (meth)acrylate, and lauryl acrylate.

[0169] In some embodiments, the curable adhesive composition comprises an epoxy resin of high Tg monofunctional (meth)acrylate monomers and / or in combination with one or more low Tg (meth)acrylate monomers. In this embodiment, based on the total weight of the monofunctional (meth)acrylate monomers, the adhesive composition comprises at least 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt% of low Tg monofunctional (meth)acrylate monomers (e.g., their polymerization units). The adhesive composition typically comprises no more than 70 wt%, 65 wt%, 60 wt%, 55 wt%, or 50 wt% of low Tg monofunctional (meth)acrylate monomers (e.g., their polymerization units). It should be understood that the preferred concentration of the low Tg monomer is influenced by the Tg and concentration of the other (meth)acrylate monomers in the adhesive composition. In the case of pressure-sensitive adhesives that are not semi-structural adhesives, the amount of low-Tg monofunctional (meth)acrylate alkyl monomers is typically at least 50%, 55%, 60%, 65%, 70%, or greater. Alternatively, or as a supplement to the low-Tg monofunctional alkyl monomers, the adhesive may contain polyurethane (meth)acrylate oligomers as low-Tg (meth)acrylate monomers.

[0170] The curable adhesive composition may also contain one or more polar monomers (e.g., their polymeric units). Representative polar monomers include acid-functional monomers, hydroxyl-functional monomers, ether-containing monomers, and nitrogen-containing monomers.

[0171] The acid functional group can be the acid itself (such as a carboxylic acid), or a portion thereof can be its salt (such as an alkali metal carboxylate). Acid functional monomers include olefinically unsaturated carboxylic acids, olefinically unsaturated sulfonic acids, olefinically unsaturated phosphonic acids, and mixtures thereof. Examples of such compounds include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, crotonic acid, citrate, maleic acid, oleic acid, β-carboxyethyl (meth)acrylate, 2-sulfoethyl methacrylate, styrene sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, vinylphosphonic acid, and mixtures thereof.

[0172] In some embodiments, such as when the adhesive is intended to adhere to metal, the adhesive composition contains little or no acid-functionalized monomers to avoid corrosion. Excessive acidic monomers can also shorten the shelf life of the tape by prematurely activating the epoxy resin to cure. Therefore, in typical embodiments, the amount of acid-functionalized monomers is zero or less than 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0.5 wt%, or 0.1 wt% of the total amount of (meth)acrylate monomers in the adhesive composition.

[0173] In a typical embodiment, the adhesive composition contains little or no nitrogen-containing monomers because such monomers can hinder the curing of cationic epoxy resins. Therefore, in a typical embodiment, the content of nitrogen-containing monomers is zero or less than 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0.5 wt%, or 0.1 wt% of the total amount of (meth)acrylate monomers in the adhesive composition.

[0174] In a typical embodiment, the adhesive composition comprises a non-acidic polar monomer, or in other words, a polar monomer that does not contain acid and nitrogen groups. One type of non-acidic polar monomer is a mono(meth)acrylate monomer containing an ether group, such as tetrahydrofurfuryl acrylate (THFA).

[0175] Another class of non-acidic polar monomers includes hydroxyl-functional (meth)acrylate monomers. Representative examples include 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-(methoxyethoxy)ethyl methacrylate, 2-methoxyethyl methacrylate, 4-hydroxybutyl acrylate, 2-phenoxyethyl acrylate, hydroxypropyl acrylate, and polyethylene glycol mono(meth)acrylate.

[0176] In some embodiments, the adhesive composition contains little or no non-acidic polar monomers having aromatic groups, such as 2-phenoxyethyl acrylate. In this embodiment, the content of the aromatic polar monomer is zero or less than 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1% of the total amount of (meth)acrylate monomers in the adhesive composition.

[0177] In some embodiments, the polar monomer has a low Tg (i.e., not greater than 0°C). In some embodiments, the polar monomer has a Tg not greater than -10°C, -20°C, -30°C, -40°C, or -50°C. The Tg of the homopolymer of the non-acidic polar monomer can be at least -50°C, -40°C, -30°C, -20°C, or -10°C. Representative examples include tetrahydrofurfuryl acrylate and 2-(2-ethoxyethoxy)ethyl acrylate. Low-Tg polar monomers can be used at relatively high concentrations to produce (meth)acrylic polymers with a Tg less than 0°C.

[0178] In some embodiments, the adhesive composition comprises a crosslinking agent. The crosslinking agent may comprise free radical polymerizable groups, such as (meth)acrylate groups. In some embodiments, the crosslinking agent comprises at least two, and typically no more than 6, 5, 4, or 3 olefinically unsaturated groups, which are capable of crosslinking the polymeric units of the (meth)acrylate polymer.

[0179] Examples of usable (e.g., aliphatic) polyfunctional (meth)acrylates include, but are not limited to, di(meth)acrylates, tri(meth)acrylates, and tetra(meth)acrylates, such as 1,6-hexanediol di(meth)acrylate, poly(ethylene glycol) di(meth)acrylate, polybutadiene di(meth)acrylate, polyurethane di(meth)acrylate, propoxylated glycerol tri(meth)acrylate, and mixtures thereof. Other crosslinking agents are described in US 4,330,590, WO2014 / 172185, WO2015 / 157350, and WO2020 / 250154; these patents are incorporated herein by reference.

[0180] In some embodiments, the adhesive composition comprises an interphase crosslinking agent containing at least one epoxy or hydroxyl group and at least one (meth)acrylate. Such compounds enable the cured epoxy resin to crosslink with a (meth)acrylate polymer. Representative crosslinking agents include 2-hydroxy-3-phenoxypropyl acrylate (HPPA) and glycidyl methacrylate (GMA). Such interphase crosslinking agents may be used in an amount of at least 0.5% or 1% by weight of the total polymerizable components of the adhesive composition, and typically not more than 10% or 5% by weight. Notably, such crosslinking agents are typically added after the formation of a (meth)acrylate copolymer from monofunctional (meth)acrylate monomers.

[0181] Referring to Example 63, the type and amount of polar monomers can be selected to induce phase separation in the adhesive composition. While compatible single-phase adhesive compositions (e.g., tapes having an adhesive layer of 10 mils (250 micrometers) thickness comprising a (meth)acrylic polymer and uncured epoxy resin) are transparent (i.e., without opacifiers such as pigments), the adhesive compositions described herein are translucent or opaque. Compatible single-phase adhesive compositions typically also have a single Tg (determined by dynamic mechanical analysis, as further described in the examples) after epoxy curing. Conversely, cured adhesive compositions according to the invention may have more than one Tg.

[0182] In some embodiments, the adhesive composition has a first Tg in the range of -10°C to 50°C. In some embodiments, the first Tg is at least -15°C, -10°C, -5°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, or 40°C. In some embodiments, the first Tg is not greater than 35°C, 30°C, 25°C, 20°C, 15°C, 10°C, 5°C, or 0°C. In some embodiments, the tan(δ) of the adhesive composition at the first Tg temperature is less than 0.85, 0.80, 0.75, 0.70, 0.65, or 0.60. In some embodiments, the tan(δ) of the adhesive composition at the first Tg temperature is at least 0.2, 0.3, or 0.4.

[0183] In some embodiments, the adhesive composition has a second Tg of at least 50°C, 55°C, 60°C, 65°C, 70°C, or 75°C. In some embodiments, the second Tg is not greater than 85°C, 80°C, 75°C, 70°C, or 65°C. In some embodiments, the tan(δ) of the adhesive composition at the second Tg temperature is less than 0.50, 0.40, or 0.30. In some embodiments, the tan(δ) of the adhesive composition at the first Tg temperature is at least 0.1, 0.15, or 0.2. Therefore, the adhesive composition has more than one phase and can also be characterized as an interpenetrating polymer network.

[0184] Other suitable compositions comprising epoxy resin and (e.g., partially polymerized) (meth)acrylate monomers for use in the manufacture of adhesive layers for transfer tapes or tapes containing multilayer films as backing are described in PA100568US01, which is incorporated herein by reference.

[0185] The adhesive composition may optionally contain a variety of additives, such as fillers, stabilizers, plasticizers, tackifiers, flow control agents, curing rate retarders, adhesion promoters (e.g., silanes and titanates), auxiliaries, impact modifiers, expandable microspheres, thermally conductive particles, electrically conductive particles, silica, glass, clay, talc, pigments, colorants, glass beads or glass bubbles, antioxidants, etc.

[0186] It is worth noting that thermally conductive adhesives typically contain thermally conductive particles.

[0187] The adhesive composition can be polymerized using various techniques, such as those described in WO2016 / 195970 (Shafer et al.); this document is incorporated herein by reference. In some embodiments, the adhesive is polymerized by solvent-free radiation polymerization, including methods using electron beams, gamma rays, and especially ultraviolet radiation. In this (e.g., ultraviolet radiation) embodiment, methacrylate monomers are typically used sparingly or not at all. Therefore, the adhesive composition contains zero or no more than 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, or 1 wt% of monomers having methacrylate groups (e.g., their polymeric units).

[0188] One method for preparing the adhesive composition includes dissolving an epoxy resin in a liquid polyol and mixing the mixture with a (meth)acrylate monomer. Such monomers can be partially polymerized. Partial polymerization provides a coatable solution of a (meth)acrylate solute polymer in one or more free-radical polymerizable solvent monomers.

[0189] The adhesive composition comprises one or more free radical initiators (e.g., photoinitiators) and cationic initiators in amounts of at least 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, or 0.5 wt%, and generally not more than 1 wt%, of the total amount of the adhesive composition. In the bonding method, the initiators may be added immediately before using the adhesive composition.

[0190] This adhesive composition typically contains a free radical initiator to polymerize (meth)acrylate monomers.

[0191] The free radical initiator can be a thermal initiator or a photoinitiator, and its type and amount can effectively polymerize the (meth)acrylic acid of the second polymerizable material. The initiator is typically used at a concentration in the range of about 0.0001 parts by weight to about 3.0 parts by weight of the composition, preferably about 0.001 parts by weight to about 1.0 parts by weight, and more preferably about 0.005 parts by weight to about 0.5 parts by weight.

[0192] Suitable thermal initiators include, but are not limited to, those selected from the group consisting of: azo compounds (such as VAZO 64 (2,2'-azobis(isobutyronitrile)), VAZO 52 (2,2'-azobis(2,4-dimethylpentanonitrile)), and VAZO 67 (2,2'-azobis-(2-methylbutyronitrile)) available from Chemours, Wilmington, DE, USA), peroxides (such as benzoyl peroxide and lauroyl peroxide), and mixtures thereof. Preferred oil-soluble thermal initiators are (2,2'-azobis-(2-methylbutyronitrile)).

[0193] Examples of photoinitiators that may be used include benzoin ethers (e.g., benzoin methyl ether or benzoin butyl ether); acetophenone derivatives (e.g., 2,2-dimethoxy-2-phenylacetophenone or 2,2-diethoxyacetophenone); 1-hydroxycyclohexylphenyl ketone; and acylphosphine oxide derivatives and acylphosphinate derivatives (e.g., bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, diphenyl-2,4,6-trimethylbenzoylphosphine oxide, isopropoxyphenyl-2,4,6-trimethylbenzoylphosphine oxide, or dimethylneoplamide phosphinate). Many photoinitiators are available, for example, under the trade name “OMNIRAD” from IGM Resins (Charlotte, NC, USA). Photoinitiators may be selected, for example, based on the desired curing wavelength and compatibility with the monomer.

[0194] In some embodiments, the cationic initiator may be characterized as a photoacid generator. Upon exposure to light energy, the photoacid generator undergoes a cleavage reaction and releases one or more Lewis or Brønsted acid molecules, which induce polymerization of the epoxy groups. Available photoacid generators are thermally stable, do not undergo heat-induced reactions with the composition, and are readily soluble or dispersed in the composition. Typical photoacid generators are those in which the initial acid has a pKa value < 0. Photoacid generators are known, and reference is made to K. Dietliker, *Chemistry and Technology of UV and EB Formulation for Coatings, Inks and Paints*, Vol. 11, SITA Technology Ltd., London, 1991. See also: Kirk-Othmer Encyclopedia of Chemical Technology, 4th edition, Supplement, John Wiley International Publishing Co., New York, 1992, pp. 253-255.

[0195] The cations that can be used as the cationic moiety of an ionizing photoinitiator include organic ononium cations, such as those described in U.S. Patents 4,250,311, 3,708,296, 4,069,055, 4,216,288, 5,084,586, 5,124,417, and 5,554,664, and such descriptions are incorporated herein by reference, including those with an aliphatic or aromatic group IVAVIIA (CAS version). The central onium salt, preferably an onium salt centered on I-, S-, P-, Se-, N-, and C-, such as those selected from sulfonium oxide, iodonium, sulfonium, selenium, pyridinium, carbium, and phosphonium, and most preferably an onium salt centered on I- and S-, such as those selected from sulfonium oxide, diaryliodonium, triarylsulfonium, diarylalkylsulfonium, dialkylarylsulfonium, and trialkylsulfonium, wherein “aryl” and “alkyl” are as defined and have up to four independently selected substituents. The substituents on the aryl and alkyl moieties will preferably have fewer than 30 carbon atoms and up to 10 heteroatoms selected from N, S, non-peroxide O, P, As, Si, Sn, B, Ge, Te, and Se. Examples include hydrocarbon groups such as methyl, ethyl, butyl, dodecyl, tetradecyl, benzyl, allyl, benzylene, vinyl, and ethynyl; hydrocarbon oxy groups such as methoxy, butoxy, and phenoxy; hydrocarbon mercapto groups such as methyl mercapto and phenoxy mercapto; hydrocarbon oxycarbonyl groups such as methoxycarbonyl and phenoxycarbonyl; hydrocarbon carbonyl groups such as formyl, acetyl, and benzoyl; hydrocarbon carbonyloxy groups such as acetoxy and cyclohexylcarbonyloxy; hydrocarbon amide groups such as acetamido and benzamide; azo; oxoboronyl; halogen groups such as chlorine, bromine, iodine, and fluorine; hydroxyl; oxygen; diphenylarsyl; diphenylantimonyl; trimethylgermanyl; trimethylsiloxy; and aromatic groups such as cyclopentadienyl, phenyl, tolyl, naphthyl, and indene. For sulfonium salts, the substituents can be further substituted by dialkyl or diarylsulfonium cations; an example would be 1,4-phenylenebis(diphenylsulfonium).

[0196] Available onium salt photoacid generators include diazonium salts, such as aryl diazonium salts; haloonium salts, such as diaryliodoonium salts; sulfonium salts, such as triarylsulfonium salts, such as triphenylsulfonium trifluoromethanesulfonate; selenium salts, such as triarylselenium salts; sulfonium oxide salts, such as triarylsulfonium oxide salts; and other miscellaneous onium salts, such as triarylphosphonium and thiopyranium salts, as well as pyranium and thiopyranium salts.

[0197] Ionized photoacid generators include, for example, bis(4-tert-butylphenyl)iodonium hexafluoroantimonate (FP5034, obtained from Hampford Research Inc., Stratford, CT, USA). ™ Syna PI-6976™ The following triarylsulfonium salts (a mixture of diphenyl(4-phenylthio)phenylsulfonium hexafluoroantimonate and bis(4-(diphenylthio)phenyl)thioether hexafluoroantimonate), (4-methoxyphenyl)phenyliodonium trifluoromethanesulfonate, bis(4-tert-butylphenyl)iodonium camphor sulfonate, bis(4-tert-butylphenyl)iodonium hexafluoroantimonate, bis(4-tert-butylphenyl)iodonium hexafluorophosphate, and bis(4-tert-butylphenyl)iodonium hexafluorophosphate were purchased from Synasia, Metachen, NJ, USA. Butylphenyl)iodonium tetraphenylborate, bis(4-tert-butylphenyl)iodonium toluenesulfonate, bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate, ([4-(octoxy)phenyl]benzeniodonium hexafluorophosphate), ([4-(octoxy)phenyl]benzeniodonium hexafluoroantimonate), (4-isopropylphenyl)(4-methylphenyl)iodonium tetra(pentafluorophenyl)borate (can be Rhodorsil 2074) ™ The following products were purchased from Bluestar Silicones, East Brunswick, NJ, USA: bis(4-methylphenyl)iodonium hexafluorophosphate (Omnicat 440 can be purchased from IGM Resins, Charlotte, NC, USA), 4-(2-hydroxy-1-tetradecoxy)phenyl]phenyliodonium hexafluoroantimonate, triphenylsulfonium hexafluoroantimonate (CT-548 can be purchased from Chitec Technology Corp. Taipei, Taiwan, China), diphenyl(4-phenylthio)phenylsulfonium hexafluorophosphate, bis(4-(diphenylthio)phenyl)sulfide bis(hexafluorophosphate), diphenyl(4-phenylthio)phenylsulfonium hexafluoroantimonate, bis(4-(diphenylthio)phenyl)sulfide hexafluoroantimonate, and the trademark Syna. PI-6992 and Syna PI-6976 (for PF6 and SbF6 salts, respectively) are blends of these triarylsulfonium salts purchased from Synascia Corporation.

[0198] A preferred photoacid generator is triarylsulfonium hexafluoroantimonate, obtained under the name "UVI6976" from Aceto Corporation (Port Washington, NY, USA) in the form of a 50% propylene carbonate solution. This solution can be dried to produce a pure solid salt, which is also a preferred photoacid generator.

[0199] In some embodiments, adhesive articles comprising adhesive-coated films and tapes are described, which include multilayer films and at least one adhesive layer.

[0200] Figure 13 A cross-section of a representative adhesive article (e.g., tape) 1300 is shown, the adhesive article comprising a multilayer film 1340 having a first main surface 1341 and an opposing main surface 1342. A first adhesive layer 1331 is disposed on the first main surface 1341 of the multilayer film 1340. The multilayer film 1340 completely spans the first adhesive layer 1331. The multilayer film may be characterized as an insulating layer. When the first adhesive layer 1331 is pressure-sensitive (e.g., prior to curing), a removable release liner 1301 may be disposed on the opposing surface of the adhesive layer.

[0201] Figure 14 A cross-section of another representative adhesive article 1400 (e.g., tape) is shown, comprising a multilayer film 1440 having a first main surface and opposing main surfaces. A first adhesive layer 1431 is disposed on the first main surface of the multilayer film. The multilayer film 1440 completely spans the first adhesive layer 1431. The multilayer film may be characterized as an insulating layer. When the first adhesive layer 1431 is a pressure-sensitive adhesive (e.g., before curing), a removable release liner 1401 may be disposed on the opposing surface of the adhesive layer. In this embodiment, a second adhesive layer 1432 is disposed on the opposing surface of the multilayer film.

[0202] Figure 15 A cross-section of another representative adhesive article 1500 (e.g., tape) is shown, comprising a multilayer film 1540 having a first main surface and opposing main surfaces. A first adhesive layer 1531 is disposed on the first main surface of the multilayer film. The multilayer film 1540 partially spans the first adhesive layer 1531. When the first adhesive layer 1531 is pressure-sensitive (e.g., prior to curing), a removable release liner 1501 may be disposed on the opposing surface of the adhesive layer. In this embodiment, a second adhesive layer 1532 is disposed on the opposing surface of an adhesive insulating layer 1560 of the multilayer film. The insulating layer 1560 may be a monolithic film or a multilayer film, such as the multilayer film described herein. A monolithic film may contain a thermoplastic polymer as described herein. In another embodiment, a third adhesive layer may be disposed on the top surface of the insulating layer 1560. The third adhesive layer may include a pressure-sensitive adhesive (e.g., prior to curing). In this embodiment, 1532 may be a non-pressure-sensitive structural adhesive as described herein.

[0203] Example

[0204] Unless otherwise specified or readily apparent from the context, all parts, percentages, ratios, etc., in the embodiments and the remainder of the specification are by weight. The following abbreviations are used in this section: g = gram, gf = gram-force, kg = kilogram, nm = nanometer, µm = micrometer, mm = millimeter, cm = centimeter, in = inch, MPa = megapascal, ℃ = degree Celsius, ℉ = degree Fahrenheit, d = day, h = hour, min = minute, N = newton, kN = kilonewton, mJ = millijoule, mbar = millibar, UV = ultraviolet light, V = volt. Units expressed in inches can be converted to cm by multiplying by 2.54.

[0205] Test methods

[0206] All tests (e.g., splitting shear, lap shear, interlaminar peel strength, Young's modulus) were performed at ambient temperature (23°C). For the splitting strength test method, the substrate included orthogonal portions of the fixtures attached to the instrument (e.g., 375, 475, 575, 675, 2075).

[0207] Splitting strength test method 1

[0208] use Figure 7 The illustrated first and second rigid aluminum substrates, machined from 6061 aluminum alloy, are manufactured according to... Figure 3 and Figure 4 The test samples. For the control samples, the adhesive layer between the first aluminum substrate and the second aluminum substrate consists only of structural adhesive. For the embodiments, the adhesive layer comprises a multilayer film substantially centered within the adhesive layer between the first aluminum substrate and the second aluminum substrate (in the thickness direction z).

[0209] Prepare a multilayer film sample that spans the entire length of the adhesive layer (in the lateral directions x and y).

[0210] Prepare edge-localized samples where the multilayer film exists only in a portion of the adhesive layer, relative to... Figure 4 The cross-sectional penetration distance of the indicated quantity.

[0211] Samples were formed using two polytetrafluoroethylene (PTFE) blocks, each machined with recesses for receiving substrates, holes for receiving pins to align the two substrates, and channels for delivering excess adhesive from the adhesive layer during sealing. The substrate surfaces were sandblasted with 220-mesh alumina abrasive and then wiped with methyl ethyl ketone solvent. Each of the two substrates was pressed into the recesses of the PTFE blocks to a certain depth to achieve a target adhesive layer thickness of approximately 3 mm after curing. When the multilayer film was fully embedded, it was positioned in the middle of the adhesive layer (1.5 mm of adhesive on each side of the multilayer). The mixed adhesive portions were dispensed as layers onto each of the exposed substrate surfaces. For these embodiments, a multilayer film measuring approximately 1.5 / 8in × 5in (extending beyond the final adhesive layer area) was placed on top of one of the dispensed adhesive layers. The two PTFE blocks, with the substrates and dispensed adhesive, were pressed together to bring the PTFE blocks together and form a cured assembly. The cured assembly was placed in an oven at 60°C for 1 hour to begin curing the adhesive, and then further cured at room temperature for at least one day. The control was prepared in the same manner, except that multilayer films were excluded.

[0212] Trim excess cured adhesive using a blade or cutting wheel. The splitting strength of the test specimens is determined by mounting each test specimen on a load frame (Model Standard C43, MTS Systems Corporation, Eden Prairie, Minnesota) at a rate of 1.3 in / min under tension using a 30 kN wedge-action tension clamp with a textured wedge face (MTS Systems Corporation, Eden Prairie, Minnesota) with short arms (including the holes in these short arms). Unless otherwise specified, the average splitting strength of the three specimens, N / inch (2.54 cm), is reported with a standard deviation of + / - one standard deviation. Splitting strength is calculated as the maximum load (N) across a 1-inch width.

[0213] Splitting strength test method 2

[0214] Manufactured according to the same procedure described for method 1 of the splitting strength test. Figure 5 and Figure 6 The test samples differed in that the PTFE gaskets were placed in the area between the substrates at a 1-inch x 1-inch angle (e.g., Figure 5 and Figure 6 (As illustrated) to seal the adhesive from the area. Therefore, the adhesive layer is recessed 1 inch relative to the outer edge of the substrate. The splitting strength of Test Method 2 is determined using a load frame and reported in the same manner as described in Splitting Test Method 1.

[0215] Splitting strength test method 3

[0216] The test sample was prepared according to splitting strength test method 1, the difference being the use of a ratio Figure 7 The rigid base shown is replaced by an L-shaped base that is less rigid and more easily deformable. The replacement base has 4-inch legs, 2-inch legs, and a 1-inch width, similar to... Figure 7 The rigid bases shown have the same legs and width dimensions. Each replacement base has a thickness of 0.9 mm (relative to...). Figure 7 The rigid substrate shown is 0.25 in thick and is formed by bending a 0.9 mm thick 5052 aluminum alloy sheet with a 1 inch × 6 inch dimension. The splitting strength of Test Method 3 is determined using a load frame and reported in the same manner as described in Splitting Test Method 1. During the application of the conformation to the article, the substrate is replaced with a different material to prevent deformation.

[0217] Method 1 for testing the shear strength of lap joints

[0218] Manufactured using a 1.6mm thick flat rectangular substrate (810, 820) of 6061 aluminum alloy with dimensions of 4in x 1in. Figure 8 Test sample 800. The bonding surface of the substrate was sandblasted with 220-mesh alumina abrasive and then cleaned by briefly immersing in heptane, followed by spraying and wiping with a mixture of isopropanol and deionized water (50 / 50 volume), and then drying. The control (not shown) consisted only of the structural adhesive between the substrates, while the examples included a multilayer film 840, which was substantially centered within and across the adhesive layers (831, 832). For samples that did not include a film in the adhesive layers, uncured adhesive was dispensed (using a static mixing nozzle) onto one of the substrates, where the adhesive thickness was greater than 1 mm. The adhesive layer thickness is set by sieving commercially available glass beads (trade name P-047 from Potters Industries Inc., Carlstadt, New Jersey, US sieve size 16-25) with a diameter of 0.85 mm or less and sprinkling approximately 3-25 beads into the adhesive layer.

[0219] Place the second substrate on the adhesive layer, aiming for an adhesive layer area of ​​approximately half an inch by one inch, and then clamp it to the first substrate using an adhesive clamp. Place the curing assembly in a 60°C oven for 1 hour to begin curing the adhesive, and then further cure at room temperature for at least one day.

[0220] For samples comprising a membrane within an adhesive layer, uncured adhesive is first dispensed (using a static mixing nozzle) onto one of the substrates with a thickness greater than 0.5 mm. The adhesive layer thickness is determined by sprinkling commercially available glass beads (trade name P-0170 from Porter Industries, Calstatt, NJ, US sieve size 40-50) with an average size of 0.365 mm into the adhesive layer, followed by placing a plasma-treated co-extruded multilayer membrane (cut to 1.625 in × 1.5 in) on the adhesive. A flat, 1.6 mm thick rectangular piece of 6061 aluminum alloy is then placed on top of the multilayer membrane and secured in place with an adhesive clamp to ensure an unformed and flat bond between the first substrate and the multilayer membrane. The assembly is then placed in a 60°C oven for 10 minutes to allow the adhesive to reach its gel point, at which point the adhesive clamp and the rectangular aluminum sheet are removed, exposing the multilayer membrane.

[0221] The second aluminum substrate was bonded to the exposed surface of the multilayer film using an adhesive in the same manner as described above for the first substrate, except that the assembly was placed in an oven at 60°C for 1 hour and then further cured at room temperature for at least one day.

[0222] The lap shear separation force of the samples was determined as follows: Each sample was mounted on a load frame (Model Standard C43, MTS Systems, Eden-Prellie, Minnesota, with a 10kN load sensor) using a 30kN wedge-action tension clamp with a textured wedge surface. Samples were loaded under tension at a rate of 2.5 mm / min (applying shear stress to the adhesive bond). The maximum load was recorded. After separation, the dimensions of the bonded area were measured using a ruler, and the bonded area was calculated. The lap shear strength of the adhesive was obtained by dividing the maximum load by the calculated bonded area. The average strength of two or three samples was reported plus or minus one standard deviation.

[0223] Method for testing interlayer peel strength

[0224] The interlaminar peel strength of the multilayer membrane at 23°C was characterized as follows. The multilayer membrane under study was cut into approximately 1in × 10in dimensions. Next, a sheet of filament tape (3M 898) measuring approximately 1in × 3in was applied to each side of the multilayer membrane, taking care not to allow the tape to extend beyond the edge of the multilayer membrane and adhere to each other. A portion of the filament tape (“tab”) was extended from one short side of the multilayer membrane sample to allow for later peeling. Next, the multilayer membrane (excluding the sides of the tab) was adhered to a peel tester (Model 2100, IMASS, Incorporated, Strongsville, Ohio) using double-sided adhesive (details available). The tab was engaged by the peel tester, and the peeling motion began at 12in / min. The peel force was recorded when the layers of the multilayer membrane separated in a 90-degree peel pattern. The average force during continuous peel separation of the layers was recorded as the interlaminar peel strength, in grams per inch (width), g / in.

[0225] Method for measuring Young's modulus of adhesives

[0226] Sheets of each adhesive were cast between the release liner to a defined thickness of approximately 1 mm using a notched bar coater. The sheets were placed in a 60°C oven for 1 hour to begin curing the adhesive, followed by further curing at room temperature for at least one day. Subsequently, dog bone tensile specimens with a neck width of 6 mm and a gauge length of 45 mm were cut using a die-cutting machine. The specimens were then mounted into a load frame (Model Standard C43, MTS Systems, Eden-Prellie, Minnesota, with a 10 kN load sensor) using a 30 kN wedge-action tension clamp with textured wedges. The specimens were then loaded under tension at a rate of 1.3 mm / min to match the strain rate of the splitting specimens. Software (MTS TestSuite) was used. ™ TW Elite ™ The Young's modulus is determined by linearly fitting the elastic portion of the obtained stress-strain curve at the strain rate of interest.

[0227] Material

[0228] DP420NS is marketed under the trade name Scotch-Weld ™ DP420NS is a two-part epoxy structural adhesive sold by 3M Company, St. Paul, Minnesota.

[0229] DP8710NS is marketed under the trade name Scotch-Weld ™DP8710NS (3M Company, St. Paul, Minnesota) is a two-part acrylic structural adhesive.

[0230] DP8610NS is marketed under the trade name Scotch-Weld ™ DP8610NS (a two-part acrylic structural adhesive sold by 3M Company, St. Paul, Minnesota)

[0231] Materials of adhesive composition

[0232] THFA (Tetrahydrofurfuryl acrylate) (San Esters, New York, NY)

[0233] IBOA Isoborneol Acrylate (Chempoint, a Univar Company, Calumet City, IL)

[0234] 2EHA 2-Ethylhexyl acrylate (BASF, Ludwigshafen, Germany)

[0235] OM651 is a benzyl dimethyl ketal photoinitiator, available under the trade name OMNIRAD 651 (iGM Resins USA, Charlotte, NC, USA).

[0236] OM819 is a bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide photoinitiator, available under the trade name OMNIRAD 819 (iGM Resins, USA).

[0237] HDDA hexanediol diacrylate crosslinking agent (AllnexUSA Inc., Alpharetta GA, Georgia)

[0238] EPON 828 is an epoxy resin composed of diglycidyl ether of bisphenol A (EEW ​​185g / eq-195g / eq) (Momentive Specialty Chemicals, Inc., Columbus, OH, Ohio)

[0239] EPON 1001 is an epoxy resin composed of diglycidyl ether of bisphenol A (EEW ​​525g / eq-550g / eq) (Momentive Chemicals Ltd.).

[0240] GPTMS 3-(glycidoxypropyl)trimethoxysilane (Chemical Technologies, Levittown PA)

[0241] UVI6976 is a 50% by weight triarylhexafluoroantimony sulfonate in propylene carbonate cationic initiator (Aceto Corporation, Port Washington NY).

[0242] ACCLAIM 2200 polyether polyol (Covestro, LLC, Leverkusen, Germany)

[0243] Multilayer optical films (MOF) The film was prepared by alternating layers of 90 / 10 coPEN and blends of 46% 90 / 10 coPEN and 54% PETG, as described above as MOF2. The film has 275 layers, each with a thickness of 70 mm–100 nm.

[0244] Multilayer film materials

[0245] PET-1 is polyethylene terephthalate (PET), also known as "PTA Clear 62" (3M Corporation, St. Paul, Minnesota).

[0246] SEPS (Styrene, Ethylene, Propylene, Styrene) is sold under the trade name KRATON 1645 (Kraton Corporation, Houston, Texas).

[0247] PP polypropylene raw material, sold under the trade name Pro-fax SR549M (Lyondell Basell, Houston, Texas)

[0248] PETG polyester copolymer, sold under the trade name Eastar GN071 (Eastman Chemical, Kingsport, Tennessee).

[0249] Preparation of multilayer films

[0250] A series of co-extruded multilayer membranes with varying levels of interlaminar peel delamination strength were prepared according to the method described in U.S. Patent No. 10,710,343. The membrane comprises four layers. Layer 1 is a poly(ethylene terephthalate) copolymer with a thickness of approximately 32 µm, also referred to herein as PET-1. Layer 2 is a styrene-ethylene-propylene-styrene (SEPS) block copolymer with a thickness of approximately 12 µm. Layer 3 is a blend of polypropylene (PP) and SEPS with a thickness of approximately 12 µm. Layer 4 is an amorphous poly(ethylene terephthalate) copolymer, also referred to herein as PETG, with a thickness of approximately 12 µm. The weakest interface in the membrane is the interface between layers 3 and 4. The weakest interface is the interface that opens during mechanical separation. The different ratios of PP to SEPS in layer 3 of the various multilayer membranes, as listed in Table 1, result in differences in their interlaminar peel delamination strengths, also listed in Table 1. "9010" membranes were collected, in which a liner membrane was applied to its PETG surface. Collect “7030” and “4060” membranes, where the liner membrane is applied to each of their surfaces. Remove the liner before including the membrane in the structural adhesive joint. Before applying the adhesive, the exposed surfaces (PET and PETG) are plasma-treated for 2 minutes in a plasma cleaning system (model Atto, Diener electronic GmbH, Ebhausen, Germany) at a power setting of 100 and an air chamber pressure of 0.1 mbar.

[0251]

[0252]

[0253] The sample preparation and testing methods described above were performed using the multilayer films in Table 1 and three different adhesive compositions. The test results are described in the table below.

[0254] Splitting strength is also expressed as a percentage of the splitting strength measured against a control having the same adhesive but without a multilayer film.

[0255]

[0256]

[0257]

[0258] Example 63 - Adhesive tape with multi-layer backing

[0259] Method A – A coatable composition comprising an acrylic polymer and monomers is prepared by: charging 350 g of acrylic monomers into a 1-quart wide-mouth flask in the following ratios: 35% 2EHA, 45% THFA, and 20% IBOA, and 0.14 g of OM651, and stirring until the photoinitiator dissolves and a homogeneous mixture is obtained. The mixture is degassed by introducing nitrogen gas into the mixture through a tube inserted into the opening of the flask cap and vigorously bubbling for at least 5 minutes. While stirring, the mixture is exposed to UV-A light, thereby partially polymerizing the monomers. The light source is an LED array with a peak emission wavelength of 365 nm. After UV exposure, air is introduced into the flask.

[0260] Method B – “Epoxy-Polyol Premix” – is prepared by charging a glass jar with 52.9 parts EPON828 and 26.4 parts EPON1001 epoxy resins and heating the slurry in an oven at 135°C until a homogeneous mixture is obtained. 20.7 parts Acclaim 2200 are added with stirring, and the mixture is cooled to ambient temperature. Just before use, the mixture is reheated to approximately 200°F (93°C) to reduce viscosity and facilitate pouring.

[0261] In a wide-mouth glass bottle, the acrylic mixture (38 parts), GPTMS (1 part), HDDA (0.24 parts), UVI6976 (3 parts), epoxy-polyol premix (58 parts), and OM819 photoinitiator (0.2 parts) from Method A are mixed. The bottle is tightly sealed with a foil-lined top cap and placed overnight on a bottle roller in the dark.

[0262] Tape manufacturing

[0263] Uncured tape was obtained by performing the following procedure on the adhesive coating formulation from the above steps. Prior to coating, a multilayer 4060 film was prepared by removing the protective backing from one side, and the exposed surfaces (PET and PETG) were plasma-treated for 2 minutes in a plasma cleaning system (Model Atto, Dina Electronics GmbH, Ebhausen, Germany) at a power setting of 100 and an air chamber pressure of 0.1 mbar. Subsequently, an adhesive coating solution layer was applied between the silicone-peel-coated PET backing and the plasma-treated 4060 film surfaces using a two-roll coater with a gap setting to produce an adhesive coating thickness of 0.068 mm. The coating was exposed to approximately 3400 mJ / cm² using multiple LEDs with a peak emission wavelength of 405 nm. 2 Total UV-A energy (approximately 1700 mJ / cm² from both sides) 2Total UV exposure was determined using a POWER PUCK II radiometer equipped with a low-power sensing head (EIT, Inc., Sterling, VA).

[0264] Comparative Example C64 - Adhesive tape with a single-layer (i.e., non-multilayer) backing.

[0265] Comparative Example C64 was prepared according to the same method described for Example 63, except that a polyethylene terephthalate film extruded to a thickness of 50 micrometers was used instead of a 4060 film. The primer side of the PET was the coated side, and the coating thickness was 0.04 mm.

[0266] Example 65 - Battery Separation with Multi-Layer Tape Wrapping

[0267] A standard 9V battery was used as an example battery to compare separation forces. The battery surface was prepared by first cleaning the surface with ethyl acetate to remove organic residues, and then scrubbing the surface with a SCOTCH-BRITE universal hand pad #7447 (3M) attached to a handheld power sander (RYOBI 2 Amp Corded 1 / 4 sheet sander, Hiroshima, Japan). The battery surface was then cleaned with methyl ethyl ketone. The adhesive tape described in Example 63 was cut into strips approximately 2.5 inches wide and approximately 3.5 inches long. Another protective film was removed and the exposed surface was cleaned with IPA, and then the exposed surface was plasma-treated for 2 minutes in a plasma cleaning system (Model Atto, Dina Electronics GmbH, Ebhausen, Germany) at a power setting of 100 and an air chamber pressure of 0.1 mbar. The multilayer tape was then exposed to UV-A radiation using an LED array (OmniCure AC8150, Excelitas Technologies, Waltham, MA) with a peak emission wavelength of 365 nm. The radiation reached 4 J / cm². 2 The total UV-A energy was determined using a POWERPUCK II radiometer (EIT, Inc., Sterling, VA). The silicone release liner was then removed, and tape was wrapped around the prepared 9V battery, trimming off any excess. Small tape overlaps were left on the narrow side of the battery. Figure 3 The illustrated first and second rigid aluminum substrates (e.g., adhesives) are manufactured according to the process of machining 6061 aluminum alloy. Figure 5Test samples were prepared. The bonding surfaces of all substrates (e.g., adhesives) were sandblasted with an abrasive (details available) and then wiped with methyl ethyl ketone solvent. A small amount of DP8710NS adhesive was applied to the end portions of the two metal corners, sufficient to cover the surface of the wide side of the 9V battery, and spacer beads with a diameter of 0.85 mm or less were sprinkled on top by sieving commercially available glass beads (trade name P-047 from Porters Industries, Calstatt, NJ, US sieve size 16-25) with a wide size distribution. The wide side of the battery was then placed on the adhesive of one of the substrates (e.g., adhesives), and then the second substrate (e.g., adhesive) was placed on top of the opposite wide side of the battery. The stacks were bonded together such that the rear edge of the battery was bonded to each aluminum substrate (e.g., as shown in the image). Figure 9 The ends of the adhesive (shown) were aligned. The adhesive was secured with C-clamps, and the samples were left in ambient conditions for over 24 hours prior to testing. Finally, the separation splitting strength of the samples was determined by using a 30kN wedge-action tension clamp with textured wedges (MTS Systems Corporation, Eden Prairie, Minnesota) with short arms (including the holes) to mount each test sample onto a load frame (Model Standard C43, MTS Systems Corporation, with a 10kN load sensor) under tension at a rate of 1.3 in / min. The maximum load was recorded as the separation splitting strength. The average separation strength of the two samples was 36 N + / - 10, with no perceived damage to the 9V battery. The samples were examined to confirm splitting between the layers of the multilayer film.

[0268] Comparative Example C66 - Battery Separation without Multi-Layer Tape Wrapping

[0269] Comparative Example C66 test sample was prepared in the same manner as described in Example 65, except that the non-multilayer tape described in Comparative Example C64 was used instead of the multilayer tape of Example 66. The average separation strength of the two samples was 251 N + / - 114, with damage to the 9V battery manifested as the metal casing being pulled apart from the core.

[0270] All samples were examined after the splitting and lap shear tests to determine the location of bond separation. For all samples, bond separation from the splitting and lap shear tests occurred at the internal interfaces of the multilayer film (i.e., between layers).

[0271] Method 2 for testing the shear strength of lap joints

[0272] use Figure 7The illustrated rigid aluminum (first) substrate 1710, machined from 6061 aluminum alloy, and the 1.6mm thick flat rectangular (second) substrate 1720, made of 6061 aluminum alloy with dimensions of 4 inches × 1 inch, are manufactured according to... Figure 17 The test sample.

[0273] The sample includes a film (e.g., a co-extruded multilayer film) 1740, which is approximately centered between a first structural adhesive layer 1731 directly adjacent to a first substrate and a second structural adhesive layer 1732 directly adjacent to a second substrate. All substrates with intended bonding surfaces were sandblasted with 220-mesh alumina abrasive and then cleaned by briefly immersing in heptane, followed by spraying and wiping with a mixture of isopropanol and deionized water (50 / 50 volume), and then drying.

[0274] First, uncured adhesive is dispensed (using a static mixing nozzle) onto the first substrate to a thickness greater than 0.5 mm. The adhesive line thickness is set by sprinkling commercially available glass beads (trade name P-0170 from Porter Industries, Calstatt, NJ, US sieve size 40-50) with an average size of 0.365 mm into the adhesive layer, followed by placing a plasma-treated co-extruded multilayer film (cut to 1.625 in × 1.5 in) on the adhesive. The second substrate is then placed on top of the multilayer film and secured in place with an adhesive jig to ensure an unformed and flat bond between the substrate and the multilayer film. The assembly is then placed in a 60°C oven for 10 minutes to allow the adhesive to reach its gel point. At this point, the adhesive jig and rectangular aluminum sheet are removed, exposing the multilayer film, and the second substrate is placed. Uncured adhesive is then dispensed (using a static mixing nozzle) onto the second substrate to a thickness greater than 0.5 mm. The adhesive line thickness is set as follows: Commercially available glass beads (trade name P-0170, from Porter Industries, Carlstadt, NJ, US sieve size 40-50) with an average size of 0.365 mm are sprinkled into the adhesive layer. The second substrate is then placed on the exposed multilayer film (bonded to the first substrate), aiming for an adhesive bonding area of ​​approximately half an inch by one inch, and then clamped to the first substrate using an adhesive clamp. The curing assembly is placed in a 60°C oven for 1 hour to begin curing the adhesive, and then further cured at room temperature for at least one day.

[0275] The lap shear separation force of the samples was determined as follows: Each sample was mounted on a load frame (Model Standard C43, MTS Systems, Eden-Prellie, Minnesota, with a 10kN load sensor) using a 30kN wedge tension clamp with a textured wedge surface (MTS Systems, Eden-Prellie, Minnesota). This 30kN wedge tension clamp was applied to sections of substrate 1720 and substrate 1710 parallel to substrate 1720. Samples were loaded under tension at a rate of 2.5 mm / min (applying shear stress to the adhesive bond). The maximum load was recorded. After separation, the dimensions of the bond shown were measured using a ruler, and the bond area was calculated. The lap shear strength of the bond was obtained by dividing the maximum load by the calculated bond area. The average strength of the three samples was reported plus or minus one standard deviation.

[0276] Method 3 for testing the shear strength of lap joints

[0277] use Figure 7 The illustrated rigid aluminum (first) substrate 1810, machined from a 6061 aluminum alloy substrate, and the 1.6mm thick flat rectangular (second) substrate 1820 of 6061 aluminum alloy with dimensions of 4 inches × 1 inch are manufactured according to... Figure 18 The test sample.

[0278] The samples included a membrane (e.g., a co-extruded multilayer membrane) 1840, which was approximately centered between a first structural adhesive layer 1831 directly adjacent to a first substrate and a second structural adhesive layer 1832 directly adjacent to a second substrate. All substrates with intended bonding surfaces were sandblasted with 220-mesh alumina abrasive and then cleaned by briefly immersing in heptane, followed by spraying and wiping with a mixture of isopropanol and deionized water (50 / 50 volume), and then drying.

[0279] The first substrate used in the lap shear strength test method 3 is a first substrate having a layered multilayer film portion produced by the splitting strength test method 3. As described in the preparation of the multilayer film, the exposed surface of the multilayer film portion is subjected to plasma treatment.

[0280] Dispense (using a static mixing nozzle) the uncured adhesive onto the second substrate to a thickness greater than 0.5 mm. The adhesive line thickness is determined by sprinkling commercially available glass beads (trade name P-0170, from Porter Industries, Calstatt, NJ, US sieve size 40-50) with an average size of 0.365 mm into the adhesive layer. Then place the second substrate onto the exposed multilayer film (bonded to the first substrate) with an adhesive bonding area of ​​approximately half an inch by one inch, and clamp it to the first substrate using an adhesive clamp. Place the curing assembly in a 60°C oven for 1 hour to begin curing the adhesive, then allow it to cure further at room temperature for at least one day.

[0281] The lap shear separation force of the sample is determined as described in Method 2 for lap shear strength testing.

[0282] Method 4 for testing the shear strength of lap joints

[0283] use Figure 7 The illustrated rigid aluminum (first) substrate 1910, machined from 6061 aluminum alloy, and the 1.6mm thick, flat rectangular second substrate 1920, made of 6061 aluminum alloy with dimensions of 4 inches × 1 inch, are manufactured according to... Figure 19 The test sample.

[0284] The samples included (e.g., layered) membrane 1940A and (e.g., multilayered) membrane 1940B. Approximately one-third of the total adhesive layer thickness was between each substrate and adjacent membranes, and one-third was between membranes (1831, 1832, 1833). The intended bonding surfaces of all substrates were sandblasted with 220-mesh alumina abrasive and then cleaned by briefly immersing in heptane, followed by spraying and wiping with a mixture of isopropanol and deionized water (50 / 50 volume), and then drying.

[0285] The first substrate used in the lap shear strength test method 3 is a first substrate having a layered multilayer film produced by the splitting strength test method 3. As described in the preparation of the multilayer film, the exposed surfaces of a portion of the layered multilayer film are subjected to plasma treatment.

[0286] First, uncured adhesive is dispensed (using a static mixing nozzle) onto the multilayer film of the first substrate to a thickness greater than 0.5 mm. The adhesive line thickness is set by sprinkling commercially available glass beads (trade name P-0170 from Porter Industries, Carlstatt, NJ, US sieve size 40-50) with an average size of 0.365 mm into the adhesive layer, and then placing a plasma-treated co-extruded multilayer film (cut to 1.625 in × 1.5 in) on the adhesive. The second substrate is then placed on top of the multilayer film and secured in place with an adhesive jig to ensure an unformed and flat bond between the substrate and the multilayer film. The assembly is then placed in a 60°C oven for 10 minutes to allow the adhesive to reach its gel point. At this point, the adhesive jig and rectangular aluminum sheet are removed, exposing the multilayer film, and the second substrate is placed. Uncured adhesive is then dispensed (using a static mixing nozzle) onto the second substrate to a thickness greater than 0.5 mm. The adhesive line thickness is set as follows: Commercially available glass beads (trade name P-0170, from Porter Industries, Carlstadt, NJ, US sieve size 40-50) with an average size of 0.365 mm are sprinkled into the adhesive layer. A second substrate is then placed on the exposed multilayer film, aiming for an adhesive bonding area of ​​approximately half an inch by one inch, and then clamped to the first substrate using an adhesive clamp. The curing assembly is placed in a 60°C oven for 1 hour to begin curing the adhesive, and then further cured at room temperature for at least one day.

[0287] The lap shear separation force of the sample is determined as described in Method 2 for lap shear strength testing.

[0288] Splitting strength test method 4

[0289] use Figure 7 The illustrated rigid aluminum first substrate, machined from 6061 aluminum alloy, and its ratio Figure 7 The rigid substrate shown is used to manufacture an L-shaped second substrate with lower rigidity and greater deformability. Figure 3 The test sample. The second substrate has 4-inch legs, 2-inch legs, and a width of 1 inch, and is... Figure 7 The rigid first base shown has the same legs and width dimensions. The second base has a thickness of 0.9 mm (relative to...). Figure 7 The rigid first substrate shown is 0.25 inches thick and is formed by bending a 0.9 mm thick 5052 aluminum alloy sheet with a 1 inch × 6 inch dimension. During the application of the conformation to the article, the second substrate deforms.

[0290] The first substrate used in the splitting strength test method 4 is a first substrate having a layered multilayer film produced by the substrate splitting strength test method 3. As described in the preparation of the multilayer film, the exposed surfaces of a portion of the multilayer film are subjected to plasma treatment.

[0291] The samples comprised a membrane (e.g., a co-extruded multilayer membrane) substantially centered between a first structural adhesive layer directly adjacent to a first substrate and a second structural adhesive layer directly adjacent to a second substrate. The intended bonding surfaces of all substrates were sandblasted with 220-mesh alumina abrasive and then cleaned by briefly immersing in heptane, followed by spraying and wiping with a mixture of isopropanol and deionized water (50 / 50 volume), and then drying.

[0292] For the three samples, the splitting strength of the splitting strength test method 4 was determined using a load frame and reported in the same manner as described in the splitting strength test method 1.

[0293] Splitting strength test method 5

[0294] use Figure 7 The exemplified rigid aluminum first substrate 2010, machined from 6061 aluminum alloy, and... Figure 7 The rigid substrate shown is a smaller, more deformable L-shaped second substrate 2020 manufactured according to... Figure 20 The test sample. The lower rigidity second base has 4-inch legs, 2-inch legs, and a width of 1 inch, compared to... Figure 7 The rigid base shown has the same legs and width dimensions. The second base, with lower rigidity, has a thickness of 0.9 mm (relative to...). Figure 7 The rigid first substrate shown is 0.25 inches thick and is formed by bending a 0.9 mm thick 5052 aluminum alloy sheet with a 1 inch x 6 inch dimension. The substrate is deformed during the application of conformation to the article.

[0295] The samples included a layered (e.g., multilayer) film 2040B and (e.g., multilayer) film 2040A, which divided the adhesive layer thickness into three parts, as previously described. All substrates intended for bonding were sandblasted with 220-mesh alumina abrasive and then cleaned by briefly immersing in heptane, followed by spraying and wiping with a mixture of isopropanol and deionized water (50 / 50 volume), and then drying.

[0296] The sample is formed using the method described in Splitting Strength Test Method 1, except that the first substrate is a first substrate having a layered multilayer film portion produced by Splitting Strength Test Method 3. As described in the preparation of the multilayer film, the exposed surfaces of the multilayer film portion are plasma-treated. The substrate (with its adhesive layer and a portion of the multilayer film present) initially used for Splitting Strength Test Method 3 is loaded into a machined PTFE block, and the remainder of the Splitting Strength Test Method 1 procedure is performed. This procedure produces a sample having a first film and a second film (i.e., a multilayer film), the first film being closest to the first substrate and comprising a portion of the multilayer film present prior to the use of Splitting Strength Test Method 3, and the second film being closest to the second (deformable) substrate. The thickness of each of the three adhesive layers of the sample is approximately 1.5 mm.

[0297] Example C67

[0298] Three samples were prepared and tested according to splitting strength test method 3 using adhesive material DP8710NS in the absence of a membrane. The mean and standard deviation of the strength measurements are given in Table A.

[0299] Example C68

[0300] Three samples were prepared and tested according to the overlap shear test method using the adhesive material DP8710NS in the absence of a membrane. The mean and standard deviation of the strength measurements are given in Table B.

[0301] Example 69

[0302] Six samples were manufactured and tested according to splitting strength test method 3 using DP8710NS adhesive material and co-extruded multilayer film MOF. The mean and standard deviation of the strength measurements are given in Table A. Compared with Example C67 (without multilayer film), the force required to separate the substrate was reduced from 1691 N / in to 372 N / in (a reduction of 22% of the value without film, for easier disassembly).

[0303] Example 70

[0304] Three samples were manufactured and tested according to splitting strength test method 4 using adhesive material DP8710NS and co-extruded multilayer film MOF. Each of the three first substrates used to manufacture the three samples was prepared from the separated rigid substrate of Example 1 (after strength testing). The rigid substrate of Example 69 (after strength testing) comprised portions of the adhesive layer and the multilayer film. The mean and standard deviation of the strength measurements are given in Table A. These strength measurements were for samples in which the first substrate had been first bonded, split-layered, and then second bonded (as in, for example, a first rework or repair scenario). Compared to Example C67 (without the multilayer film), the force required to separate the substrate was reduced from 1691 N / in to 617 N / in (a reduction of 36% of the value without the film, making it easier to remove the adhesive bond for rework or repair).

[0305] Example 71

[0306] Two samples were manufactured and tested according to splitting strength test method 4 using adhesive material DP8710NS and co-extruded multilayer film MOF. Each of the two first substrates used to manufacture the two samples was prepared from the separated rigid substrate of Example 70 (after strength testing). The rigid substrate of Example 70 (after strength testing) comprised portions of the adhesive layer and the multilayer film. The mean and standard deviation of the strength measurements are given in Table A. These strength measurements were for samples in which the first substrate had been first bonded, split-delaminated, second bonded (as in, for example, a first rework or repair scenario) and split-delaminated, and finally third bonded (as in, for example, a second rework or repair scenario) and split-delaminated. Compared to Example C67 (without the multilayer film), the force required to separate the substrate was reduced from 1691 N / in to 655 N / in (a reduction of 39% of the value without the film, making it easier to remove the adhesive bond in the rework or repair).

[0307] Example 72

[0308] A sample was manufactured and tested according to splitting strength test method 4 using adhesive material DP8710NS and co-extruded multilayer film MOF. The first substrate used to manufacture the sample was prepared from the separated rigid substrate of Example 71 (after strength testing). The rigid substrate of Example 71 (after strength testing) comprised portions of the adhesive layer and the multilayer film. Strength measurements are given in Table A. This strength measurement was for a sample in which the first substrate had been first bonded, split-delaminated, second bonded (as in, for example, a first rework or repair scenario), split-delaminated, third bonded (as in, for example, a second rework or repair scenario), and finally fourth bonded (as in, for example, a third rework or repair scenario), split-delaminated. Compared to Example C67 (without the multilayer film), the splitting force required to delaminate the substrate was reduced from 1691 N / in to 776 N / in (a reduction to 45.9% of the value without the film, making it easier to remove the adhesive bond in rework or repair).

[0309] Example 73

[0310] Three samples were manufactured and tested using adhesive material DP8710 and a co-extruded multilayer MOF film, according to method 2 for lap shear strength testing. The mean and standard deviation of the strength measurements are given in Table B. The lap shear strength was 8.7 MPa, compared to 10.3 MPa for Example C68 (without the multilayer film). That is, the adhesive retained 84% of the lap shear strength when the multilayer film was present, indicating that high lap shear performance was retained.

[0311] Example 74

[0312] Three samples were manufactured and tested according to lap shear strength test method 3 using adhesive material DP8710NS and co-extruded multilayer film MOF. Each of the three first substrates used to manufacture the three samples was prepared from the separated rigid substrate of Example 69 (after strength testing). The rigid substrate of Example 69 (after strength testing) comprised portions of the adhesive layer and the multilayer film. The mean and standard deviation of the strength measurements are given in Table B. These strength measurements were for samples in which the first substrate had been first bonded, split-layered, and then second bonded (as in, for example, a first rework or repair scenario) for lap shear strength measurement. The lap shear strength was 10.1 MPa, compared to 10.3 MPa for Example C68 (without the multilayer film). That is, when the multilayer film is present, the lap shear strength of the adhesive is retained by 98%, which indicates that the adhesive bond retains high lap shear performance for rework or repair.

[0313] Example 75

[0314] Samples were manufactured and tested according to lap shear strength test method 3 using adhesive material DP8710NS and co-extruded multilayer film MOF. The first substrate used to manufacture the samples was prepared from the separated rigid substrate of Example 70 (after strength testing). The rigid substrate of Example 70 (after strength testing) comprised portions of the adhesive layer and the multilayer film. The strength measurement results are given in Table B. This strength measurement was performed on samples in which the first substrate had been first bonded, delaminated by splitting, second bonded (as in, for example, a first rework or repair scenario) and delaminated by splitting, and then third bonded (as in, for example, a second rework or repair scenario) for the lap shear strength measurement. The lap shear strength was 6.0 MPa, compared to 10.3 MPa for Example C68 (without the multilayer film). That is, when the multilayer film was present, the adhesive retained 58% of its lap shear strength, indicating that the adhesive bond for rework or repair retains high lap shear performance.

[0315] Example 76

[0316] Samples were manufactured and tested according to lap shear strength test method 3 using adhesive material DP8710NS and co-extruded multilayer film MOF. The first substrate used to manufacture the samples was prepared from the separated rigid substrate of Example 71 (after strength testing). The rigid substrate of Example 71 (after strength testing) comprised portions of the adhesive layer and the multilayer film. The strength measurement results are given in Table B. This strength measurement was performed on samples in which the first substrate had been first bonded, through split delamination, second bonded (as in, for example, a first rework or repair scenario) through split delamination, third bonded (as in, for example, a second rework or repair scenario) through split delamination, and then fourth bonded (as in, for example, a third rework or repair scenario) for the lap shear strength measurement. The lap shear strength was 5.3 MPa, compared to 10.3 MPa for Example C68 (without the multilayer film). That is, when the multilayer film was present, the adhesive retained 51% of its lap shear strength, indicating that the adhesive bond for rework or repair retains high lap shear performance.

[0317] Example 77

[0318] Samples were manufactured and tested according to method 3 of the lap shear strength test, using adhesive material DP8710NS and a co-extruded multilayer film MOF. The first substrate used to manufacture the samples was prepared from the separated rigid substrate of Example 72 (after the strength test). The rigid substrate of Example 72 (after the strength test) comprised portions of the adhesive layer and the multilayer film. The strength measurement results are given in Table B. This strength measurement was performed on samples in which the first substrate had been first bonded, through split delamination, second bonded (as in, for example, a first rework or repair scenario) through split delamination, third bonded (as in, for example, a second rework or repair scenario) through split delamination, fourth bonded (as in, for example, a third rework or repair scenario) through split delamination, and then fifth bonded (as in, for example, a fourth rework or repair scenario) for the lap shear strength measurement. The lap shear strength was 10.7 MPa, compared to 10.3 MPa for Example C68 (without the multilayer film). In other words, when multiple films are present, the adhesive retains 104% of its lap shear strength, which means that the adhesive bond retains high lap shear performance for rework or repair.

[0319]

[0320]

[0321] It is worth noting that the second, third, fourth, and fifth components represent reworked, repaired, reused, or recycled articles, as well as combinations thereof. For example, the second component could be a reworked article, the third and fourth components could be repaired articles, and the fifth component could be a recycled article.

[0322] Example 78

[0323] Six samples were manufactured and tested according to splitting strength test method 3 using adhesive material DP8710NS and co-extruded multilayer film 4060. The mean and standard deviation of the strength measurements are given in Table C. Compared to Example C67 (without multilayer film), the force required to separate the substrate decreased from 1691 N / in to 369 N / in (a reduction of 22% of the value without film, for easier removal). After testing, the thickness of the residual adhesive layer plus the thickness of the residual portion of the multilayer film (also referred to herein as a delamination film) present on the rigid adhesive was approximately 1.3 mm.

[0324] Example 79

[0325] Three samples were manufactured and tested according to splitting strength test method 4 using adhesive material DP8710NS and co-extruded multilayer film 4060. Each of the three first substrates used to manufacture the three samples was prepared from the separated rigid substrate of Example 78 (after the strength test). The rigid substrate of Example 78 (after the strength test) included a residual adhesive layer and a delaminated portion of the multilayer film. The total thickness of the residual adhesive layer and delaminated film present on the rigid substrate after the test in Example 78, plus the additional layer of co-extruded multilayer film 4060 (also referred to herein as a repair film), plus the adhesive material DP8710NS (also referred to herein as a repair adhesive) inserted between the additional layer of the multilayer film and the delaminated film of Example 78, was approximately 2.5 mm. That is, the total thickness of the two adhesive layers plus the two co-extruded multilayer films used for the rebonded part of Example 79 was approximately 92% greater than the total thickness of one adhesive layer and one co-extruded multilayer film (1.3 mm) of the original bonded part of Example 78 (in other words, 192% of the total thickness of one adhesive layer and one co-extruded multilayer film (1.3 mm) of the original bonded part of Example 78. The mean and standard deviation of the strength measurements are given in Table C. These strength measurements were performed on samples in which a first substrate had been first bonded, split and delaminated, and then second bonded (as in, for example, rework or repair scenarios). Compared to Example C67 (without the multilayer membrane), the force required to separate the substrate was reduced from 1691 N / in to 273 N / in (a reduction of 16% of the value without the membrane, making it easier to remove adhesive bonds used in rework or repair).

[0326] Example 80

[0327] Three samples were manufactured and tested according to lap shear strength test method 2 using adhesive material DP8710 and co-extruded multilayer film 4060. The mean and standard deviation of the strength measurements are given in Table D. The lap shear strength was 4.0 MPa, compared to 10.3 MPa for Example C68 (without the multilayer film). That is, an lap shear strength of more than 2 MPa was retained when the multilayer film was present, which indicates that useful lap shear properties were retained.

[0328] Example 81

[0329] Three samples were manufactured and tested according to lap shear strength test method 3 using adhesive material DP8710NS and co-extruded multilayer film 4060. Each of the three first substrates used to manufacture the three samples was prepared from the separated rigid substrate of Example 78 (after strength testing). The rigid substrate of Example 78 (after strength testing) comprised portions of the adhesive layer and the multilayer film. The mean and standard deviation of the strength measurements are given in Table D. These strength measurements were for samples in which the first substrate had been first bonded, split-layered, and then second bonded (as in, for example, rework or repair scenarios). The lap shear strength was 2.5 MPa, compared to 10.3 MPa for Example C68 (without the multilayer film). That is, when the multilayer film is present, an lap shear strength of more than 2 MPa is retained, which indicates that useful lap shear properties are retained for adhesive bonding in rework or repair.

[0330]

[0331]

[0332] Example 82

[0333] Example 79 can be repeated, except that the repair adhesive and repair film used in Example 79 are replaced with the tape of Example 63. The tape of Example 63 comprises a co-extruded multilayer film backing (4060) with a thickness of about 0.068 mm and an adhesive layer with a thickness of about 0.068 mm. The total thickness of the tape is about 0.14 mm. As a result of replacing the repair adhesive and repair film used in Example 79 with the tape of Example 63 (also referred to herein as repair tape), the total thickness of the residual adhesive layer and the layered film present on the rigid substrate after the test in Example 78, plus the repair tape applied to the layered film, will be about 1.44 mm. That is, the total thickness of the two adhesive layers plus the two co-extruded multilayer films of the rebonded part of Example 79 will be about 0.14 mm (11%) more than the total thickness of one adhesive layer and one co-extruded multilayer film (1.3 mm) of the original bonded part of Example 78 (in other words, 111% of the total thickness of one adhesive layer and one co-extruded multilayer film (1.3 mm) of the original bonded part of Example 78).

Claims

1. An article comprising a first substrate; a second substrate; at least one adhesive layer disposed between the first substrate and the second substrate; and a multilayer film within at least a portion of the adhesive layer.

2. The article of claim 1, wherein the multilayer film has an interlayer peel delamination strength of at least 10 g / inch, 50 g / inch, 100 g / inch, 200 g / inch, or 500 g / inch (2.54 cm) at 23 °C.

3. The article of claims 1-2, wherein the article is subjected to a temperature of at least 60 °C or 70 °C during normal use of the article.

4. The article of claim 1, wherein the first substrate and optionally the second substrate comprise a metal in contact with the adhesive layer.

5. The article of claims 1-4, wherein the article is a battery pack.

6. The article of claim 5, wherein the first metal substrate is a battery cell and the second substrate is a cooling plate.

7. The article of claim 5, wherein the first substrate and the second substrate are electrochemical cells.

8. The article of claims 1-7, wherein the multilayer film comprises at least two layers comprising different thermoplastic polymers.

9. The article of claims 1-8, wherein a component or layer of the multilayer film has a Tg of at least 70 °C, 80 °C, 90 °C, 100 °C, 115 °C, 120 °C, or 125 °C.

10. The article of claims 1-9, wherein the multilayer film has a melting temperature of at least 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, or 280 °C.

11. The article of claims 1-10, wherein the multilayer film comprises at least two layers that differ in crystallinity.

12. The article of claims 1-11, wherein the multilayer film comprises a polyester polymer, a polyolefin polymer, or a combination thereof.

13. The article of claims 1-12, wherein the multilayer film comprises at least 3, 4, 5, 6, 7, 9, 10, 50, 100, or 200 layers.

14. The article of claim 13, wherein the multilayer film comprises a layer having a thickness of at least 50 nm, 75 nm, 100 nm, 250 nm, 500 nm, 1 micron, 5 microns, 10 microns, or 25 microns.

15. The article of claims 1-14, wherein the multilayer film completely spans or partially spans the adhesive layer.

16. The article of claim 15, wherein the multilayer film partially spans the adhesive layer, and the article further comprises an insulating layer adhesively bonded between the multilayer film and the first substrate or the second substrate. ​ 17. The article of claims 1-16, wherein the adhesive layer has a middle region disposed between two opposing edge regions, and the multilayer film is present at one or both edge regions.

18. The article of claims 1-17, wherein the adhesive layer is indented relative to the edges of the first and second substrates.

19. The article of claims 1-18, wherein the multilayer film is disposed between a first adhesive layer bonding the first substrate to the multilayer film and a second adhesive layer bonding the second substrate to the multilayer film.

20. The article of claim 19, wherein the first adhesive layer comprises the same or a different adhesive composition as the second adhesive layer.

21. The article of claims 1-20, wherein the first adhesive layer and optional second adhesive layer have a Young's modulus of less than 2000 MPa, 1700 MPa, 1000 MPa, 500 MPa, 250 MPa, or less than 100 MPa.

22. The article of claims 1-21, wherein the multilayer film has an interlayer peel delamination strength of at least 50 gf / inch at 23°C, and the first adhesive layer and optional second adhesive layer have a Young's modulus of less than 1700 MPa.

23. The article of claims 1-22, wherein the adhesive layer has a lap shear strength of at least 2 MPa, 3 MPa, 5 MPa, 10 MPa, 15 MPa, or 20 MPa at 23°C.

24. The article of claim 23, wherein the article has a cleavage strength of less than 5000 N / inch, 2000 N / inch, 1500 N / inch, 1000 N / inch, 750 N / inch, 500 N / inch, or 250 N / inch at 23°C.

25. The article of claim 24, wherein the article has a cleavage strength of less than 1000 N / inch at 23°C, and the adhesive layer has a lap shear strength of at least 3 MPa at 23°C.

26. The article of claims 1-25, wherein the adhesive layer comprises a curable adhesive comprising (meth)acrylate moieties, polyurethane moieties, epoxy moieties, or a combination thereof; wherein the curable adhesive is cured.

27. The article of claim 26, wherein the curable adhesive is not a pressure sensitive adhesive after curing.

28. The article of claims 26-27, wherein the curable adhesive comprises an epoxy resin and at least one polymer comprising a (meth)acrylic polymer.

29. The article of claims 26-28, wherein the curable adhesive comprises polymerized units of a low Tg monofunctional (meth)acrylate monomer, wherein a homopolymer thereof has a glass transition temperature (Tg) of less than 0°C.

30. The article of claims 26-29, wherein the curable adhesive comprises polymerized units of a non-acidic polar (meth)acrylate monomer.

31. The article of claims 26-30, wherein the curable adhesive further comprises a multifunctional (meth)acrylate crosslinker or an interphase crosslinker containing both (meth)acrylate groups and epoxy groups.

32. The article of claims 26-31, wherein the curable adhesive has two Tgs after curing, wherein the first Tg is in the range of -10°C to 50°C and the second Tg is greater than 50°C, 55°C, 60°C, 65°C, 70°C, 75°C.

33. The article of claims 1-32, further comprising at least one additional multilayer or monolithic film positioned within at least a portion of the adhesive layer.

34. The article of claims 1-33, wherein the multilayer film has at least two different interlayer peel delamination strengths, or the article comprises at least two (e.g., multilayer) films having different delamination strengths.

35. An article comprising a first substrate; a second substrate; at least one adhesive layer disposed between the first substrate and the second substrate; and a film positioned within at least a portion of the adhesive layer; wherein the adhesive layer has a bond strength to the film that is greater than the interfacial strength of the film, and the adhesive layer has a bond strength to the substrate that is also greater than the interfacial strength of the film.

36. The article of claim 35, wherein the article is further characterized by claims 1-34.

37. A method of disassembly comprising providing an article of claims 1-34; applying a force to separate the first substrate from the second substrate by delaminating the (e.g., multilayer) film.

38. The method of claim 37, wherein the substrates and / or the adhesive layer and / or the (e.g., multilayer) film are further described in claims 2-34.

39. An adhesive article (e.g., a tape) comprising: a (e.g., multilayer) film having a first major surface and an opposing major surface; a first adhesive layer disposed on the first major surface of the (e.g., multilayer) film; and an optional second adhesive layer disposed on the second major surface of the (e.g., multilayer) film.

40. The adhesive article of claim 39, wherein the adhesive layer has a bond strength to the film that is greater than the interfacial strength of the film at ambient temperature.

41. The adhesive article of claims 39-40, wherein the (e.g., multilayer) film partially spans the adhesive layer, and the tape further comprises an insulating layer.

42. The adhesive article of claim 41, wherein the insulating layer is a monolithic film or a multilayer film.

43. The adhesive article of claims 39-42, wherein the first adhesive layer and optional second adhesive layer are pressure sensitive adhesives.

44. The adhesive article of claims 39-43, wherein the (e.g., multilayer) film and / or the adhesive layer are further characterized by claims 2-34.

45. An adhesive article for use in manufacturing, reworking, repairing, reusing, or recycling a battery module.

46. A method of manufacturing an article, the method comprising: bonding a first metal substrate to a second substrate with at least one adhesive layer; wherein a (e.g., multilayer) film is located within at least a portion of the adhesive layer.

47. The method of claim 46, wherein the substrates and / or the adhesive layer and / or the (e.g., multilayer) film are further described in claims 2-34.

48. The method of claims 46 and 47, wherein the adhesive layer and the (e.g., multilayer) film are applied to the first substrate and / or the second substrate in order.

49. The method of claims 46-48, wherein at least one adhesive layer is provided together with the (e.g., multilayer) film as an adhesive article of claims 40-46.

50. The method of claims 46-49, wherein the (e.g., multilayer) film is surface treated with an adhesion promoter prior to application of the adhesive layer.

51. The method of claims 46-50, wherein the method of manufacturing is a method of reworking a defective article, a method of repairing an article, a method of reusing an article, or a method of recycling an article.

52. An article comprising: a first substrate; an adhesive layer disposed on the substrate; and a layered (e.g., multilayer) film bonded to the adhesive layer.

53. The article of claim 52, wherein the layered film is a multilayer film.

54. The article of claims 52-53, wherein the first substrate, the adhesive layer, or the multilayer film are further characterized by claims 1-34.

55. A method of manufacturing, reworking, repairing, reusing, or recycling an article, the method comprising: providing a portion of a first article, the first article comprising a first substrate, an adhesive layer disposed on the substrate, and a layered (e.g., multilayer) film bonded to the adhesive layer; applying an adhesive to the first substrate, a second substrate, or a combination thereof; bonding the first substrate to the second substrate with the adhesive, thereby forming a second article.

56. The method of claim 55, further comprising applying a monolithic film or a multilayer film to at least a portion of the adhesive layer.

57. The method of claim 56, wherein the film comprises a tab, a marker, or a combination thereof indicating one or more layered locations.

58. The method of claims 55-57, wherein the film and at least one adhesive are applied as a tape. ​ 59. The method of claims 55-58, further comprising surface treating the layered film, substrate, or applied monolithic or multi-layered film prior to applying the adhesive and / or applying the second substrate.

60. The method of claims 55-59, wherein the method is repeated at least 2, 3, or 4 times.

61. The method of claim 60, wherein the same film is layered and adhesively bonded at least 2, 3, or 4 times.

62. The method of claim 60, wherein two or more films are each layered and adhesively bonded at least once.

63. The method of claims 56-62, wherein the thickness of the adhesive applied to the layered film and the thickness of the applied monolithic or multi-layered film are selected such that when combined with the thickness of the layered film, the total thickness is within 50%, 40%, 30%, 20%, or 10% of the thickness of the (e.g., multi-layered) film of the first article prior to layering.

64. The method of claims 56-63, wherein the thickness of the adhesive applied to the layered film and the thickness of the applied monolithic or multi-layered film are selected such that when combined with the thickness of the layered film, the total thickness is + / - 0.5 mm, 0.25 mm, 0.1 mm, or 0.05 mm of the thickness of the (e.g., multi-layered) film of the first article prior to layering.

65. The method of claims 55-64, wherein the first article has a first bond thickness between the first substrate and the second substrate, and the applied adhesive and film are selected such that the bond thickness between the first substrate and the second substrate of the second article is + / - 10% of the first bond thickness.

66. A reworked or repaired (e.g., battery module) article, comprising: a first substrate; a second substrate; one or more adhesive layers disposed between the first substrate and the second substrate, defining a bond thickness; wherein the reworked or repaired (e.g., battery module) article has a bond thickness that is + / - 10% compared to the article prior to reworking or repairing.

67. The reworked or repaired (e.g., battery module) article of claim 66, further comprising a film within at least a portion of the adhesive layers.

68. The reworked or repaired (e.g., battery module) article of claims 66-67, wherein the film is a multi-layered film.

69. The reworked or repaired (e.g., battery module) article of claims 66-67, further characterized by claims 2-34.

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