Adhesive structure

Abstract

The present invention relates to an adhesive structure comprising: a first substrate having a conductive surface or a non-conductive surface; a first cured adhesive layer or a first cured electrochemically debondable adhesive layer; a conductive foil; a second cured electrochemically debondable adhesive layer, which may be the same as or different from the first cured electrochemically debondable adhesive layer; and a second substrate having a conductive surface wherein the first cured adhesive layer is disposed between the first substrate and the conductive foil, and wherein the second cured adhesive layer is disposed between the second substrate and the conductive foil. The adhesive structure may be debonded by applying a voltage between the surfaces of the selected substrates.

Description

TECHNICAL FIELD

[0001] The present invention relates to bonded structures formed by using curable and debondable adhesive compositions and which can be debonded from the particular substrate to which they are applied. BACKGROUND

[0002] Adhesive bonding and polymeric coatings are commonly used in the assembly and finishing of manufactured articles. They are used in place of mechanical fasteners, such as screws, bolts, and rivets, to provide adhesion in manufacturing processes with reduced machining costs and greater adaptability. Adhesive bonding distributes stresses evenly, reducing the likelihood of fatigue and sealing the joint from corrosive substances.

[0003] While adhesive bonding thus provides many advantages over mechanical fasteners, it is often difficult to disassemble adhesively bonded objects when required in practical applications. Removal of the adhesive by mechanical processes, such as by sandblasting or by wire brushing, is typically precluded, in part because the adhesive is disposed between substrates and is thus inaccessible or difficult to abrade without damaging the substrate surfaces. Disassembly by application of chemicals and / or high temperatures can be effective, but can be time-consuming and complex to perform. Furthermore, the aggressive chemicals and / or harsh conditions required can damage the substrates being separated, making them unsuitable for subsequent applications.

[0004] Accordingly, there is a need for adhesives for use in bonded structures that can be debonded without damaging the substrates. BRIEF DESCRIPTION OF DRAWINGS

[0005] Figure 1 Examples illustrate bonded structures according to the present invention.

[0006] Figure 2a , 2b and 2c illustrate debonded structures. SUMMARY

[0007] The present invention relates to a bonded structure comprising: a first substrate having an electrically conductive surface or a non-conductive surface; a first cured adhesive layer or a first cured electrochemically debondable adhesive layer; an electrically conductive foil; a second cured electrochemically debondable adhesive layer, which can be the same or different from the first cured electrochemically debondable adhesive layer; and a second substrate having an electrically conductive surface, wherein the first cured adhesive layer is disposed between the first substrate and the electrically conductive foil, and wherein the second cured adhesive layer is disposed between the second substrate and the electrically conductive foil.

[0008] The present invention also relates to a method for detaching an adhesive structure according to the invention, the method comprising the steps of: i) applying a voltage between a second substrate and a conductive foil, or a first substrate having a conductive surface and a conductive foil, or a conductive foil, or a first substrate and a second substrate having a conductive surface, to form an anode interface and a cathode interface; and ii) detaching the surfaces. Detailed Implementation

[0009] The invention is described in more detail in the following paragraphs. Unless expressly indicated to the contrary, each aspect thus described may be combined with any one or more other aspects. In particular, any feature indicated as preferred or advantageous may be combined with any one or more other features indicated as preferred or advantageous.

[0010] In the context of this invention, unless the context otherwise requires, the terminology used shall be interpreted in accordance with the following definitions.

[0011] As used in this article, the singular forms “a,” “an,” “a,” “the,” and “the” include both singular and plural referents, unless the context clearly specifies otherwise.

[0012] The terms “comprising” and “including” as used herein are synonymous with “containing” or “containing”, and are inclusive or open-ended, and do not exclude additional unlisted members, elements or method steps.

[0013] As used in this article, the term " consists of "Exclude any elements, components, members, or method steps that are not specified."

[0014] Words " preferably " preferably " desirably "and" in particular "The term is frequently used herein to refer to embodiments of this disclosure that may provide particular benefits in certain circumstances. However, the enumeration of one or more preferred, preferred, desired, or particular embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude those other embodiments from the scope of this disclosure."

[0015] As used throughout this application, the term " may "or" may "Use in a licensed sense—meaning possible—rather than in a mandatory sense."

[0016] The list of numerical endpoints includes all numbers and fractions that fall into the corresponding range, as well as the listed endpoints.

[0017] Unless otherwise stated, all percentages, parts, proportions, etc. mentioned in this document are based on weight.

[0018] When expressing equivalent, concentration, or other values or parameters in the form of ranges, preferred ranges, or preferred upper and lower limits, it is to be understood that any range, preferred range, or preferred upper or lower limit, as the case can be, is specifically contemplated even if only one number or value is explicitly recited within the range, the preferred range, or the preferred upper or lower limit.

[0019] All references cited in this specification are hereby incorporated by reference in their entirety.

[0020] Unless otherwise defined, all terms (including technical and scientific terms) used in the present application have the meaning commonly understood by one of ordinary skill in the art to which this application belongs. By further guidance, term definitions are included to better define the present teachings.

[0021] The present application relates to an adhesive structure comprising: a first substrate having a conductive surface or a non-conductive surface; a first cured adhesive layer or a first cured electrochemically debondable adhesive layer; a conductive foil; a second cured electrochemically debondable adhesive layer, which can be the same or different than the first cured electrochemically debondable adhesive layer; and a second substrate having a conductive surface, wherein the first cured adhesive layer is disposed between the first substrate and the conductive foil, and wherein the second cured adhesive layer is disposed between the second substrate and the conductive foil.

[0022] The adhesive structure according to the present application comprises a first substrate. The first substrate can be a non-conductive substrate or a non-conductive substrate having a conductive surface or a conductive substrate.

[0023] The first substrate, when non-conductive, can be shown in the form of a layer, wherein the layer can be composed of a sheet or film of resin-containing material, or glass. Non-limiting examples of resin-containing materials are polybutylene terephthalate and polyamide.

[0024] The adhesive structure according to the present application comprises a second substrate. The second substrate has a conductive surface.

[0025] When the first substrate is electrically conductive and the second substrate can be in the form of a layer, wherein the layer can be composed of a metal film, a metal sheet, a metal mesh or grid, deposited metal particles, a resin-containing material rendered electrically conductive by means of electrically conductive elements disposed therein, or an electrically conductive oxide layer. As exemplary electrically conductive elements, one can mention silver wires, single-walled carbon nanotubes and multi-walled carbon nanotubes. As exemplary electrically conductive oxides, one can mention: doped indium oxides, such as indium tin oxide (ITO); doped zinc oxides; antimony tin oxides; cadmium stannate; and zinc stannate. In addition to the choice of electrically conductive material, one skilled in the art will recognize that, in the case where the electrically conductive substrate is in the form of a grid or mesh, its limited contact with the first and second cured adhesive layers can result in a reduced effectiveness of the debonding operation.

[0026] The adhesive structure according to the present application comprises an electrically conductive foil. The electrically conductive foil can be a solid sheet / film / foil of electrically conductive material, or a mesh, or a set of wires made of electrically conductive material.

[0027] Preferably, the electrically conductive foil is selected from the group consisting of aluminum foil and copper foil.

[0028] The adhesive structure according to the present application comprises a first cured adhesive or a first cured electrochemically debondable adhesive.

[0029] The first cured adhesive, when present, can be any ordinary commercially available structural adhesive. The only requirement for the structural adhesive is that it is suitable for bonding the first substrate and the electrically conductive foil together. The first cured adhesive is preferably selected from the group consisting of 1 k epoxy adhesives, 2k epoxy adhesives, epoxy tape adhesives, 1 k acrylate adhesives, 2k acrylate adhesives, pressure sensitive adhesives, polyurethane adhesives, and epoxy acrylate hybrid adhesives.

[0030] Commercially available structural adhesives suitable for use in the present application include, but are not limited to: LOCTITE HHD 3128 epoxy adhesive, LOCTITE HHD 6010 polyurethane adhesive, and LOCTITE HHD 8540 acrylate adhesive, available from Henkel Corporation.

[0031] The first cured electrochemically debondable adhesive, when present, is preferably selected from the group consisting of electrochemically debondable 1 k epoxy adhesives, electrochemically debondable 2k epoxy adhesives, electrochemically debondable epoxy tape adhesives, electrochemically debondable 1 k acrylate adhesives, electrochemically debondable 2k acrylate adhesives, electrochemically debondable pressure sensitive adhesives, and electrochemically debondable epoxy acrylate hybrid adhesives.

[0032] The adhesive structure according to the present application comprises a second cured electrochemically debondable adhesive. The second cured electrochemically debondable adhesive can be the same or different from the first cured electrochemically debondable adhesive.

[0033] The second cured electrochemically debondable adhesive is preferably selected from the group consisting of electrochemically debondable 1k epoxy adhesives, electrochemically debondable 2k epoxy adhesives, electrochemically debondable epoxy tape adhesives, electrochemically debondable 1k acrylate adhesives, electrochemically debondable 2k acrylate adhesives, electrochemically debondable pressure sensitive adhesives, and electrochemically debondable epoxy acrylate hybrid adhesives.

[0034] The first cured electrochemically debondable adhesive and the second cured electrochemically debondable adhesive comprise a resin and an electrolyte.

[0035] The resin suitable for use in the present application is selected from the group consisting of epoxy resins, acrylate resins, and mixtures thereof.

[0036] The electrolyte suitable for use in the present application preferably comprises at least one salt having a formula selected from the group consisting of: Ammonium Pyridinium Phosphonium Imidazolium Oxazolium Guanidinium and Thiazolium wherein: R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are independently selected from the group consisting of hydrogen, C1-C 18 alkyl, C3-C 18 cycloalkyl, C6-C 18 aryl, C7-C 24 aralkyl, C2-C 20 alkenyl, -C(O)R q , -C(O)OH, -CN, and -NO2; and R q is C1-C6alkyl.

[0037] For the sake of completeness, the terms C1-C 18 alkyl, C3-C 18 cycloalkyl, C6-C 18 aryl, C7-C24 aralkyl, C2-C 20 alkenyl expressly includes groups wherein one or more of the hydrogen atoms is replaced by a halogen atom (e.g. C1-C 18 haloalkyl) or a hydroxyl group (e.g. C1-C 18 hydroxyalkyl). In particular, it is preferred that R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are independently selected from hydrogen, C1-C 12 alkyl, C1-C 12 haloalkyl, C1-C 12 hydroxyalkyl and C3-C 12 cycloalkyl. For example, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 may be independently selected from hydrogen, C1-C6alkyl, C1-C6haloalkyl and C1-C6hydroxyalkyl.

[0038] The counter anion (X") which can be used in the electrolyte is not particularly intended to be limited. Exemplary anions can be selected from: • halide ions; • pseudohalide and halogen-containing compounds of the formulae PF6 - , CF3SO3 - , (CF3SO3)2N - , CF3CO2 – and CCl3CO2 – ; • CN - , SCN - and OCN - ; • phenolate; • sulfate, sulfite and sulfonic acid radicals of the general formulae SO4 2- , HSO4 - , SO3 2- , HSO3 - , R a OSO3 - and R a SO3 - ; • phosphate radicals of the general formulae PO4 3- , HPO4 2- , H2PO4 - , R a PO4 2- , HRa PO4 - and R a R b PO4 - phosphate; • phosphonates and phosphinates of the general formula R a HPO3 - , R a R b PO2 – and R a R b PO3 – ; • phosphites of the general formula PO3 3- , HPO3 2- , H2PO3 - , R a PO3 2- , R a HPO3 – and R a R b PO3 - ; • phosphonites and phosphinates of the general formula R a R b PO2 - , R a HPO2 - , R a R b PO - and R a HPO - ; • carboxylate anions of the general formula R a COO - ; • hydroxycarboxylate anions and sugar acid anions; • saccharinate (salt of o-benzoic acid sulfimide); • borate anions of the general formula BO3 3- , HBO3 2- , H2BO3 - , R a R b BO3 - , R a HBO3 - , R a BO3 2- , B(OR a )(OR b )(OR c ;)(OR d ) - , B(HSO4) - and B(R a SO4) - borate; • boronate of general formula R a BO2 2- and R a R b BO - ; • carbonate and carbonates of general formula HCO3 - , CO3 2- and R a CO3 – ; • silicate and silicates of general formula SiO4 4- , HSiO4 3- , H2SiO4 2- , H3SiO4 - , R a SiO4 3- , R a R b SiO4 2- , R a R b R c SiO4 - , HR a SiO4 2- , H2R a SiO4 – and HR a R b SiO4 - ; • silicate and silicates of general formula R a SiO3 3- , R a R b SiO2 2- , R a R b R c SiO - , R a R b R c SiO3 - , R a R b R c SiO2 – and R a R b SiO3 2-alkyl- and arylsilanolate groups of the general formula R pyridinate and pyrimidinate groups; carboxylic acid imides, bis(sulfonyl)imides and sulfonylimides of the general formula methylates of the general formula sulfides, hydrosulfides, polysulfides, hydro-polysulfides and thiolates of the general formula R a O - alkoxides and aryloxides of the general formula R sulfides, hydrosulfides, polysulfides, hydro-polysulfides and thiolates of the general formula R 2- , HS - , [S v ] 2- , [HS v ] - and [R a S] - sulfides, hydrosulfides, polysulfides, hydro-polysulfides and thiolates of the general formula R wherein in these general formulae v is a positive integer from 2 to 10.

[0039] R a , R b , R c and R d are independently selected from the group consisting of hydrogen, Ci-C 12 alkyl, C5-C 12 cycloalkyl, C5-C 12 heterocycloalkyl, C6-C 18 aryl and C5-C 18 heteroaryl.

[0040] Based on the definitions in the above list, preferred anions are selected from the group consisting of halides; pseudohalides and halogen-containing compounds as defined above; carboxylate anions, in particular formate, acetate, propionate, butyrate and lactate; hydroxycarboxylate anions; pyridinate and pyrimidinate groups; carboxylic acid imides, bis(sulfonyl)imides and sulfonylimides; sulfate, in particular methylsulfate and ethylsulfate; sulfite; sulfonate, in particular methanesulfonate; and phosphate, in particular dimethylphosphate, diethylphosphate and di(2-ethylhexyl)-phosphate.

[0041] Suitable electrolytes are preferably selected from the group consisting of 1-methylimidazolium bis(trifluoromethylsulfonyl)imide; 3-methylimidazolium bis(trifluoromethylsulfonyl)imide; 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide; 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide; 1-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; tetraethylphosphonium bis(trifluoromethylsulfonyl)imide; tetra- butylphosphonium bis(trifluoromethylsulfonyl)imide; tripeptidyl (tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide; trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide; 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide; 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; and mixtures thereof.

[0042] The first and second cured electrochemically debondable adhesives typically comprise additional components. The choice of additional components depends on the resin used and whether the composition is a 1k or 2k composition. Additional components are illustrated in more detail in the following examples.

[0043] As described above, the present application provides an adhesive structure comprising: a first substrate having an electrically conductive surface or a non-conductive surface; a first cured adhesive layer or a first cured electrochemically debondable adhesive layer; an electrically conductive foil; a second cured electrochemically debondable adhesive layer, which can be the same or different from the first cured electrochemically debondable adhesive layer; and a second substrate having an electrically conductive surface, wherein the first cured adhesive layer is disposed between the first substrate and the electrically conductive foil, and wherein the second cured adhesive layer is disposed between the second substrate and the electrically conductive foil.

[0044] To prepare such a structure, the surfaces of the first and second substrates and the electrically conductive foil can optionally be pretreated by cleaning the surfaces to remove foreign matter therefrom.

[0045] The adhesive - the first adhesive or the first and second electrochemically debondable adhesives - is applied by conventional application methods, for example: brushing; roller coating, for example using a 4-roll application apparatus where the composition is solvent-free or using a 2-roll application apparatus for solvent-containing compositions; doctor blade application; printing methods; and spray application methods, including but not limited to air atomized spray, air assisted spray, airless spray and high volume low pressure spray.

[0046] A first adhesive layer or first electrochemically debondable adhesive layer is then applied to the inner surface of the first substrate and a second electrochemically debondable adhesive is applied to the inner surface of the second substrate. An electrically conductive foil is then placed on the surface of the first or second adhesive layer and then subsequently the two layers are brought into contact such that the electrochemically debondable adhesive composition is interposed between the substrates and the electrically conductive foil is located between the adhesive layers. The adhesive structure according to the present application is illustrated in Figure 1 .

[0047] It is recommended that the adhesive is applied to the surface at a wet film thickness of 10 to 500 μm. The application of thinner layers within this range is more economical and can reduce the likelihood of harmful thick cured regions. However, strict control must be exercised when applying thinner coatings or layers to avoid the formation of discontinuous cured films.

[0048] Curing of the applied composition of the present application is generally carried out at a temperature in the range of 40°C to 200°C, preferably 50°C to 175°C, and in particular 75°C to 175°C. The appropriate temperature depends on the particular compounds present and the desired rate of curing, and can be determined in individual cases by the person skilled in the art, if necessary using simple preliminary tests. Of course, curing at lower temperatures within the aforementioned range is advantageous because it avoids the requirement to heat or cool the mixture substantially from the ambient temperature which usually prevails.

[0049] As shown in the accompanying Figure 1 , there is provided an adhesive structure in which a layer of cured first adhesive is arranged between a first substrate and an electrically conductive foil. A layer of cured second adhesive is arranged between a second substrate and the electrically conductive foil.

[0050] The present application relates to a method of debonding an adhesive structure.

[0051] The method of debonding an adhesive structure according to the present application comprises the steps of: i) applying a voltage between a surface of a second substrate and an electrically conductive foil, or a first substrate having an electrically conductive surface and an electrically conductive foil, or an electrically conductive foil, or a first substrate having an electrically conductive surface and a second substrate, to form an anodic interface and a cathodic interface; and ii) debonding the surface.

[0052] The two conductive substrate layers are in electrical contact with a power source, which can be a battery or an AC driven direct current (DC) power source. The positive and negative terminals of that power source are shown in a fixed position, but one of skill in the art will of course recognize that the polarity of the system can be reversed. In other words, either the first substrate and conductive foil are in electrical contact with the power source, or the second substrate and conductive foil are in electrical contact with the power source, or both sides of the conductive foil are in electrical contact with the power source.

[0053] When a voltage is applied between each of the conductive substrates, an electric current is supplied to the adhesive composition disposed therebetween. This initiates electrochemical reactions at the interface of the substrate and adhesive composition, which are understood to be oxidation reactions at the positively charged interface or anodic interface, and reduction reactions at the negatively charged interface or cathodic interface. The reactions are believed to weaken the adhesive bond between the substrates, thereby enabling the debondable composition to be easily removed from the substrates.

[0054] As Figure 2a , 2b and illustrated in FIGS. 2a, 2b, 2c, debonding occurs at the positive interface, that is, the interface between the adhesive composition and the conductive surface, and the conductive interface is in electrical contact with the positive terminal. The black arrow indicates the debonding site.

[0055] However, it is noted that the composition of the adhesive layer can be adjusted such that debonding occurs at the positive interface or the negative interface or both simultaneously. For some embodiments, applying a voltage between the two surfaces to form an anodic interface and a cathodic interface results in debonding occurring simultaneously at the adhesive / substrate interface of both the anode and the cathode. The current can be applied in any suitable waveform, provided that there is sufficient total time under each polarity to allow debonding to occur. Sine, square, and triangular waveforms can be suitable in this regard, and can be applied by a controlled voltage or a controlled current source.

[0056] Without intending to limit the invention, it is believed that the debonding operation can be effectively performed with initiation of at least one and preferably both of the following conditions: a) the voltage applied is 0.5 to 100 V; and b) the duration of the voltage application is 1 second to 60 minutes. In cases where the peeling of the conductive substrate from the cured adhesive is to be facilitated by the application of force, such as by a weight or spring, it can only be necessary to apply the electric potential for a few seconds. In some embodiments, the application of a 5 V potential for 10 minutes is sufficient to have a debonding effect, while in some embodiments, the application of a 3.5 V potential for 30 minutes is sufficient.

[0057] It is intended that after debonding, the adhesive composition is only on the first substrate or the second substrate, which means that one of the substrates is essentially free of adhesive.

[0058] The following examples are illustrative of the application and are not intended to limit the scope of the application in any way.

[0059] Example The following materials were used in the examples: Example 1 Parts (A) and (B) of Composition 1 were prepared according to Table 1 below herein.

[0060] Table 1

[0061] Parts (A, B) were loaded into separate chambers of a 50 g cartridge in equal amounts by weight and the ends were sealed. The cartridge was then loaded into a cartridge-gun and a mixing head was installed at the front end. By applying a constant pressure to the trigger, the two parts were pushed into the mixing head to ensure thorough mixing before application to the substrate.

[0062] An adhesive structure according to the application was prepared according to the structure in Figure 1 The first and second substrates were stainless steel and the aluminum foil was a common aluminum foil. The first and second cured electrochemically debondable adhesive layers were the same adhesive according to the formulation in Table 1.

[0063] The adhesive bond was easily removed on the foil side by applying a voltage of 30 V for 20 minutes. Alternatively, the adhesive bond was also easily removed on the stainless steel side with a scraper.

[0064] In addition, another adhesive structure according to the application was prepared according to the structure in Figure 1 The first and second substrates were stainless steel and a copper foil was used as the conductive foil. The first and second cured electrochemically debondable adhesive layers were the same adhesive according to the formulation in Table 1.

[0065] The adhesive bond was easily removed on the foil side by applying a voltage of 30 V for 20 minutes. Alternatively, the adhesive bond was also easily removed on the stainless steel side with a scraper.

[0066] Example 2 Part (A) of the three two-part (2K) compositions was prepared according to Table 2 below herein: Table 2

[0067] Part (B) was prepared identically for each of the three two-part (2K) compositions according to Table 3 below herein: Table 3

[0068] For each example, the parts (A, B) were loaded into separate chambers of a 50 g cartridge and sealed on both ends. The cartridge was then loaded into a glue gun and a mixing head was installed on the front end. By applying a constant pressure to the trigger, the two parts were pushed into the mixing head to ensure thorough mixing prior to application to the substrate. The weight ratio of part A to part B in the examples was: 6.5: 1 (Example 1); 7.5: 1 (Example 2); and 4.5: 1 (Example 3).

[0069] An adhesive structure according to the present application was prepared according to the structure in Figure 1 The first and second substrates were stainless steel and the aluminum foil was ordinary aluminum foil. The first and second cured electrochemically debondable adhesive layers were the same adhesive according to the formulation in Table 2 and 3.

[0070] A voltage of 30 V was applied for 20 minutes and the adhesive bond was easily removed on the foil side. Alternatively, the adhesive bond was also easily removed with a spatula on the stainless steel side.

[0071] Example 3 The following chemicals were used in the examples: Duro-Tak 195A from Henkel Corporation Duro-Tak AH115 from Henkel Corporation Duro-Tak 183 from Henkel Corporation 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIM NTf) from Sigma Aldrich The compositions were prepared according to Table 4.

[0072] Table 3

[0073] The compositions were prepared by mixing the ingredients. The compositions were shaped as pressure sensitive films by applying them to release liners (silicone foils) and subsequently heating at 110 °C for three minutes. The PSA films prepared had a thickness of 120 pm.

[0074] An adhesive structure according to the present application was prepared according to the structure in Figure 1 The first and second substrates were stainless steel and the aluminum foil was ordinary aluminum foil. The first and second cured electrochemically debondable adhesive layers were the same PSA adhesive according to the formulation in Table 4.

[0075] A voltage of 30 V was applied for 20 minutes and the adhesive bond was easily removed on the foil side. Alternatively, the adhesive bond was also easily removed with a spatula on the stainless steel side.

[0076] Example 4 The following chemicals were used in the examples: Duro-Tak 195A from Henkel Corporation Dynacoll 7130 from Evonik Nipol 1312LV from Zeon Chemicals 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIM TFSI) from Sigma Aldrich 1-Butyl-3-methylimidazolium bis(fluorosulfonyl)imide (BMIM FSI) from Iolitec 1-Dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (Dodecyl TFSI) from Iolitec The compositions were prepared according to Table 5.

[0077] Table 5

[0078] The compositions were prepared by mixing the ingredients. The compositions were shaped as pressure sensitive films by applying them on release liners (silicone foils), which were stored overnight in a fume hood at room temperature and subsequently heated for three minutes at 110 °C. The prepared PSA films had a thickness of 120 pm.

[0079] The adhesive structure according to the present application was prepared according to the structure in Figure 1 The first and second substrates were stainless steel and the aluminum foil was a common aluminum foil. The first and second solidified electrochemically debondable adhesive layers were the same PSA adhesive according to the formulation in Table 5.

[0080] A voltage of 30 V was applied for 20 minutes and the adhesive bond was easily removed on the foil side. Alternatively, the adhesive bond was also easily removed with a spatula on the stainless steel side.

Claims

1. An adhesive structure, comprising: The first substrate has a conductive surface or a non-conductive surface; First cured adhesive layer or first cured electrochemically debonded adhesive layer; Conductive foil; The second cured electrochemically detangleable adhesive layer may be the same as or different from the first cured electrochemically detangleable adhesive layer. as well as The second substrate has a conductive surface. The first cured adhesive layer is disposed between the first substrate and the conductive foil, and the second cured adhesive layer is disposed between the second substrate and the conductive foil.

2. The adhesive structure according to claim 1, wherein, if present, the first curing adhesive is selected from 1k epoxy adhesive, 2k epoxy adhesive, epoxy tape adhesive, 1k acrylate adhesive, 2k acrylate adhesive, pressure-sensitive adhesive, polyurethane adhesive, and epoxy-acrylate hybrid adhesive.

3. The adhesive structure according to claim 1 or 2, wherein the first cured electrochemically detangleable adhesive, if present, and the second cured electrochemically detangleable adhesive are independently selected from electrochemically detangleable 1k epoxy adhesives, electrochemically detangleable 2k epoxy adhesives, electrochemically detangleable epoxy tape adhesives, electrochemically detangleable 1k acrylate adhesives, electrochemically detangleable 2k acrylate adhesives, electrochemically detangleable pressure-sensitive adhesives, and electrochemically detangleable epoxy-acrylate hybrid adhesives.

4. The adhesive structure according to claim 3, wherein the first cured electrochemically debonded adhesive and the second cured electrochemically debonded adhesive comprise a resin and an electrolyte.

5. The adhesive structure according to claim 4, wherein the resin is selected from epoxy resin, acrylate resin and mixtures thereof.

6. The adhesive structure according to claim 4, wherein the electrolyte is selected from 1-methylimidazolium bis(trifluoromethanesulfonyl)imide; 3-methylimidazolium bis(trifluoromethanesulfonyl)imide; 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; 1-butyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide; 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; 1-methyl-3-octylimidazolium Onmium bis(trifluoromethanesulfonyl)imide; 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; 1-dodecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; tetraethylphosphonium bis(trifluoromethanesulfonyl)imide; tetrabutylphosphonium bis(trifluoromethanesulfonyl)imide; tridecyl(tetradecyl)phosphonium bis(trifluoromethanesulfonyl)imide; trihexyltetradecylphosphonium bis(trifluoromethanesulfonyl)amide; 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide; 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; 1-dodecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; and mixtures thereof.

7. The adhesive structure according to claim 1, wherein the conductive foil is selected from aluminum foil and copper foil.

8. A method for detaching the adhesive structure according to claim 1, the method comprising the following steps: i) Apply voltage between the following surfaces Second substrate and conductive foil or First substrate with conductive surface and conductive foil or conductive foil or First substrate and second substrate having conductive surfaces To form an anode interface and a cathode interface; and ii) Debond the surface.

9. The method of claim 8, wherein the voltage applied in step i) is from 0.5 to 100 V and is preferably applied for a duration from 1 second to 60 minutes.

Images