Method for separating joined articles

Abstract

The present disclosure relates to a method for detaching a bonded article, the method comprising the following steps: a) providing a bonded article comprising at least one layer of a first adhesive interposed between two substrate surfaces, wherein the bonded article further comprises at least one layer of a second adhesive interposed between the two substrate surfaces, wherein: the layer or each layer of the first adhesive has a dry film thickness of 10 to 500 μm; and wherein the first adhesive is a polyurethane adhesive selected from aqueous polyurethane dispersion adhesives and polyurethane hot melt adhesives; b) C10 to C26 fatty acids; salts of C10 to C26 fatty acids; at a temperature of 20 to 90°C; A step of treating the bonded article with a solution in a polar solvent of at least one compound selected from the group consisting of C1-C4 alkyl esters of C10 to C26 fatty acids, wherein the solution has a pH of 3 to 14; and, c) a step of separating at least one layer of the first adhesive from an interposed state between the two substrate surfaces.

Description

Technology Field

[0001] The present disclosure relates to the debonding of adhesively bonded articles. More specifically, the present disclosure relates to the use of a solution of a long-chain fatty acid or its salt or ester in a polar solvent in the debonding of adhesively bonded articles. Background Technology

[0002] Adhesive bonds and polymer 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 reduce machining costs and provide bonds with greater adaptability in manufacturing processes. Adhesive bonds evenly distribute stresses, reduce the risk of fatigue, and seal joints against corrosive species.

[0003] While adhesive bonds offer many advantages over mechanical fasteners, disassembling adhesively bonded objects tends to be difficult when required in actual applications. Removal of adhesives via mechanical processes, such as sandblasting or wire brushing, is often partially excluded because the adhesive is placed between the substrates, making it inaccessible or difficult to abrade without damaging the substrate surfaces. Disassembly via the application of aggressive chemicals and / or high temperatures, as disclosed in US Patent No. 4,171,240 (Wong) and US Patent No. 4,729,797 (Linde et al.), 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, rendering them unsuitable for subsequent applications. This can be particularly detrimental when the substrates themselves have high economic value, as can be the case with bonded electrical components and metallic materials.

[0004] WO 01 / 30932 A2 (Henkel KGaA) describes the reversible separation of adhesively bonded composites by applying alternating electromagnetic fields. The adhesively bonded composite comprises at least one primer coating containing nanoscale particles having ferromagnetic, ferrimagnetic, superparamagnetic, or piezoelectric properties. By applying alternating electromagnetic fields to the primer coat associated with the adhesively bonded composites, a large amount of heat is generated locally. When the primer layer is interposed between the substrate and the thermoplastic adhesive layer, the local heat generation causes softening of the thermoplastic resin. Conversely, when the primer layer is interposed between the substrate and the thermosetting adhesive layer, the local heat generation can split the cross-linking structure of the binder matrix. In both cases, strong local heating of the boundary layer enables the separation of the semi-adhesive substrate at low force inputs.

[0005] EP 4 011 996 A1 (Henkel AG & Co. KGaA) relates to a method for separating two substrates bonded by an adhesive. The method comprises: i) treating two substrates bonded by an adhesive with a disbonding agent comprising acetone and / or oleic acid at a temperature of 20°C to 90°C; and ii) removing the substrates from the adhesive.

[0006] WO2021 / 249749 A1 (BASF SE) discloses a method for disbonding a bonded article, wherein the article comprises at least two components bonded together by a polyurethane adhesive selected from aqueous polyurethane dispersion adhesives and polyurethane hot melt adhesives. At least one of the components is a thermoplastic polyurethane. The components are disbonded by treating with an aqueous surfactant composition at elevated temperatures.

[0007] It is considered that there is still a need in the art to provide an effective method for disjointing bonded articles that can be performed in a simple and efficient manner without requiring harsh chemicals, elevated temperatures, mechanical wear, or the incidental application of significant force. Additionally, it would be advantageous to provide a method in which the separated substrates can retain their utility and be reused or recycled.

[0008] According to a first aspect of the present disclosure, a bonded article is provided comprising at least one layer of a first adhesive interposed between two substrate surfaces, said bonded article further comprising at least one layer of a second adhesive interposed between the two substrate surfaces, wherein:

[0009] A layer or each layer of the first adhesive has a dry film thickness of 10 to 500 μm, for example, 30 to 300 μm; and,

[0010] The first adhesive is a polyurethane adhesive selected from water-based polyurethane dispersion adhesives and polyurethane hot melt adhesives.

[0011] Typically, the bonded article will comprise: a first substrate having an inner surface; and a second substrate having an inner surface, wherein layers of the first and second adhesives are interposed between the inner surfaces of the first and second substrates. In important embodiments, at least one of the first and second substrates is metallic. Independently of, or in addition to, it is preferable that at least one layer of the first adhesive be in direct contact with the surface of the substrate.

[0012] The first and second adhesives are distinct from each other. The second adhesive should preferably have a higher intra-layer cohesive strength than the first adhesive when determined by comparative testing of the adhesives under tensile stress applied to the layers of the adhesives. As used herein, the term "intra-layer cohesive strength" refers to the amount of force required to separate the layers of adhesive by cohesive failure when measured in a direction perpendicular to the plane of the layer and according to ASTM F88-94. In important embodiments, the second adhesive may have an intra-layer cohesive strength at least 10% greater than the intra-layer cohesive strength of the first adhesive. In an alternative expression not intended to be mutually exclusive with that presented above, the intra-layer cohesive strength of the first adhesive may be 2 to 8 MPa, and the intra-layer cohesive strength of the second adhesive may be at least 10 MPa, e.g., 10 to 100 MPa.

[0013] With respect to the first adhesive, the aqueous polyurethane dispersion adhesive may be of the 1-part (1K) or 2-part (2K) type. It is preferable that the polyurethane dispersion adhesive be of the 2-part (2K) type. More specifically, in an important embodiment, the first adhesive is obtained by curing a 2-part (2K) aqueous composition comprising the following:

[0014] p) Part 1 including the following:

[0015] (pi) At least one anionic polyurethane polymer having pendant hydroxyl groups; and,

[0016] q) A second part comprising at least one polyisocyanate compound having pendant -NCO groups,

[0017] Here, the 2-part (2K) aqueous composition is characterized by a molar ratio of active hydrogen atoms to -NCO groups in the composition of 5:1 to 1:5.

[0018] In certain embodiments, part p) of the 2-part (2K) aqueous composition comprises at least one anionic polyurethane polymer characterized by: a hydroxyl functional value of 2 to 4; a hydroxyl value of 0.5 to 10 mg KOH / g, preferably 0.5 to 4 mg KOH / g; and a weight average molecular weight (Mw) of 50 to 200 kDa, preferably 50 to 150 kDa, more preferably 50 to 125 kDa. Independently of or in addition to the selection of this polyurethane polymer, part q) of the 2-part (2K) aqueous composition preferably comprises a linear aliphatic polyisocyanate.

[0019] Providing a layer(s) of the first adhesive—particularly as a layer disposed directly on the surface of the substrate—represents an important location for attack by the disjunction solution, and particularly by the disjunction solution described herein below. At least partial removal of the layer(s) of the first adhesive through treatment with the disjunction solution allows for easy separation of the bonded substrates.

[0020] According to a second aspect of the present disclosure, in the disassembly of an adhesively bonded article as defined above and in the appended claims: C 10 to C 26 Fatty acids; C 10 to C 26 Salts of fatty acids; and C 10 to C 26 The use of a solution in a polar solvent of at least one compound selected from the group consisting of C1-C4 alkyl esters of fatty acids is provided, wherein the deconjugation solution has a pH of 3 to 14. The deconjugation solution may have a pH of, for example, 3 to 7 or 3 to 6.

[0021] The debonding solution is based on the weight of the solution, C 10 to C 26 Fatty acids; C 10 to C26 Salts of fatty acids; and C 10 to C 26 It is preferable to include at least one compound selected from the group consisting of C1-C4 alkyl esters of fatty acids in an amount of 5 to 30 weight%, preferably 5 to 25 weight%.

[0022] At least one of the above compounds of the deconjugation solution is: C 16 -C 18 Monounsaturated fatty acids; C 16 -C 18 Salts of monounsaturated fatty acids; and C 16 -C 18 Good results were obtained when selected from the group consisting of C1-C4 alkyl esters of monounsaturated fatty acids. And in a particularly effective embodiment, the at least one compound of the deconjugation solution is selected from the group consisting of: oleic acid; salts of oleic acid; and C1-C2 alkyl esters of oleic acid.

[0023] The polar solvent of the deconjugation solution preferably comprises or consists of at least one compound selected from the group consisting of water; polyalkylene glycol dialkyl ethers; and dibasic esters. Independently of or in addition to this statement of preference, the deconjugation solution further comprises, based on the weight of the solution, at least one surfactant selected from the group consisting of nonionic surfactants and anionic surfactants in an amount of 0.5 to 50 weight%, preferably 0.5 to 40 weight%.

[0024] The present disclosure further provides a method for detaching a joined article, the method comprising the following steps:

[0025] a) a step of providing a bonded article as defined above and in the appended claims, wherein the bonded article comprises at least one layer of a first adhesive interposed between two substrate surfaces, and the bonded article further comprises at least one layer of a second adhesive interposed between the two substrate surfaces, wherein:

[0026] A layer or each layer of the first adhesive has a dry film thickness of 10 to 500 μm; and,

[0027] The step of providing the bonded article, wherein the first adhesive is a polyurethane adhesive selected from water-based polyurethane dispersion adhesives and polyurethane hot melt adhesives;

[0028] b) At a temperature of 20 to 90°C, for example, 30 to 75°C, C 10 to C 26 Fatty acids; C 10 to C 26 Salts of fatty acids; and C 10 to C 26 A step of treating an article conjugated with a solution in a polar solvent of at least one compound selected from the group consisting of C1-C4 alkyl esters of fatty acids, wherein the solution has a pH of 3 to 14; and,

[0029] c) A step of separating at least one layer of the first adhesive from the interposition between the two substrate surfaces.

[0030] In an effective embodiment, the treatment step of this method comprises immersing the bonded article in the solution. Separately, the treatment step is characterized by a contact time of 0.1 to 24 hours, preferably 0.5 to 20 hours.

[0031] Where embodiments of the present disclosure are described above as having specific embodiments, any one or more of such embodiments may be implemented in or combined with any of additional embodiments, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and variations and combinations thereof remain within the scope of the present disclosure.

[0032] definition

[0033] The singular forms "a," "an," and "the" used herein include plural referents unless the context clearly indicates otherwise.

[0034] As used herein, the terms “comprising,” “comprises,” and “comprised of” are synonymous with “including,” “includes,” “containing,” or “contains,” and do not exclude additional, unmentioned members, elements, or method steps that are comprehensive or open-ended.

[0035] As used herein, the term "consisting of" excludes any unspecified element, component, member, or method step. For completeness, the term "comprising" encompasses "consisting of".

[0036] The words “preferred,” “preferably,” “desirably,” and “particularly” are frequently used herein to refer to embodiments of the present disclosure that may provide specific advantages under specific circumstances. However, the reference to one or more preferred, preferred, desirable, or specific embodiments does not imply that other embodiments are unusable, nor is it intended to exclude such other embodiments from the scope of the present disclosure.

[0037] The word "exemplary" is used herein to mean that it functions as an example, case, or illustration. Any mode or design described herein as "exemplary" should not be interpreted as necessarily being more desirable or advantageous than other modes or designs. Rather, the use of the word "exemplary" is intended to present concepts in a concrete manner.

[0038] As used throughout this application, the word "may" is used in a permissive sense—that is, to mean having the possibility—and is not used in a mandatory sense.

[0039] Spatially relative terms such as "inner," "outer," "top," "back," "above," "below," "left," and "right" may be applied herein to describe the relationship between one component and other component(s) as illustrated in the drawings. Clearly, all such spatially relative terms refer only to the orientations illustrated in the drawings for ease of illustration and are not necessarily limiting, considering that assemblies in use may take on orientations and configurations different from those illustrated in the drawings.

[0040] The term "plural" as used herein is defined as two or more than two.

[0041] When quantities, concentrations, dimensions, and other parameters are expressed in the form of ranges, desirable ranges, upper limits, lower limits, or desirable upper and lower limits, any ranges obtainable by combining any upper limit or desirable value with any lower limit or desirable value should also be understood as specifically disclosed, regardless of whether the obtained ranges are explicitly mentioned in the context.

[0042] Additionally, according to standard understanding, a weight range expressed as "0 to x" specifically includes 0 weight%: the component defined by the said range may be absent from the material or may be present in the material in an amount of x weight% or less.

[0043] The molecular weights mentioned in this specification can be measured by gel permeation chromatography (GPC) using polystyrene correction standards as performed according to ASTM 3536.

[0044] The term "acid value" refers to the determination of the mass (mg) of potassium hydroxide (KOH) required to neutralize 1 g of a compound. The acid value can be determined by potentiometric analysis according to DIN EN ISO 2114.

[0045] The term "hydroxyl value" as used herein is defined as the mass (mg) of potassium hydroxide required to neutralize absorbed acetic acid upon acetylation of 1 gram of a chemical containing free hydroxyl groups. The hydroxyl value can be determined according to DIN 53240.

[0046] As used herein, the term "flash point" refers to the minimum temperature at which a liquid releases vapor at a concentration sufficient to form an ignitable mixture with air near the liquid surface within a test vessel. This can be determined using appropriate current standard test methods, among which the standard flash point test method by ASTM D-56 Tag Closed Tester; and the standard flash point test method by ASTM D93 Pensky-Martens Closed Tester may be mentioned.

[0047] The viscosities of the compositions described herein are measured using a Brookfield viscometer, Model RVT, under standard conditions of 20°C and 50% relative humidity (RH), unless otherwise specified. The viscometer is calibrated using silicone oils of known viscosities varying from 5,000 cps to 50,000 cps. A set of RV spindles attached to the viscometer is used for calibration. Measurements of the coating compositions are performed using the No. 6 spindle at a speed of 20 revolutions per minute for 1 minute until the viscometer is equilibrated. The viscosity corresponding to the equilibration reading is then calculated using calibration.

[0048] As used herein, room temperature is 23°C plus or minus 2°C.

[0049] As used herein, "ambient conditions" refers to the ambient temperature and pressure where the adhesive composition, the release solution, or the bonded article is located.

[0050] As used herein, "curing" of a water-based primer composition refers to the formation of a coating on a substrate: curing involves crosslinking reaction(s), but further encompasses the evaporation (drying) of water and, if present, a co-solvent from the composition; and the adhesion of the particulate or dispersed phase of the composition. Such curing may be performed under ambient conditions or by intentional exposure to heat and / or irradiation. The degree of curing may be partial or complete: in particular, the degree of crosslinking (%) may be determined by dynamic mechanical thermal analysis (DMTA) using a Polymer Laboratories MK III DMTA Analyzer under an inert gas atmosphere.

[0051] Unless otherwise noted, the term "particle size" refers to the maximum axis of a particle. For particles that are generally spherical, the maximum axis is the diameter.

[0052] As used herein, "d 50 "Particle size" means that, by volume, at least 50% of the particles have a particle size diameter less than a specific value. Unless otherwise noted, the particle size is determined by dynamic light scattering (DLS).

[0053] As used herein, the term "solids content" refers to the weight percentage of non-volatile components in the composition. Solids content may be determined as the reciprocal of the volatile content obtained according to the ASTM D2369 standard test method for the volatile content of coatings.

[0054] In the context of the present disclosure, “2-part (2K) compositions” are understood to be compositions in which the first part (A) and the second part (B) must be stored in separate containers due to their (high) reactivity. The two parts are mixed only immediately before application and then react with the formation of a bond and consequently a polymer network, typically without further activation. Higher temperatures may be applied herein to accelerate the crosslinking reaction.

[0055] As used herein, the term “aqueous primer composition” refers to a composition that actually comes into contact with a substrate to be primed. The term “aqueous” means that the solvent or carrier fluid of the composition mainly or primarily comprises water, so that water constitutes at least 50 weight percent, e.g., at least 60 weight percent or at least 70 weight percent of the continuous liquid phase of the composition.

[0056] As used herein, “metallic” means any type of metal, metal alloy, or mixture thereof. As used herein, the term “alloy” refers to a material composed of two or more metals or a metal and a nonmetal, which is closely bonded by being fused together and dissolved into one another when typically melted.

[0057] As used herein, an "active hydrogen compound" is a compound comprising at least one hydrogen atom that can be easily dissociated in an aqueous environment. Preferably, the hydrogen atom is attached to a nitrogen atom, an oxygen atom, a phosphorus atom, or a sulfur atom.

[0058] The "ionic polyurethane" used herein contains hydrophilic ionizable groups.

[0059] As used herein, the term “blocked” refers to a compound reacted with a second compound having a “blocking group” such that the reactive functional group is not available until the blocking group is removed. The blocking group may be selectively removed at an appropriate point in the synthesis sequence: the triggering event may be, in particular, moisture, heat, or irradiation. Examples of blocked isocyanates include those co-reacted with phenol, methyl ethyl ketoxime, or ε-caprolactam.

[0060] As used herein, the term "debonding composition" refers to a composition that comes into actual contact with the bonded articles. Such contact may occur in a so-called "bath" having a shape, size, and arrangement such that at least a portion of the substrate can be immersed therein. Additionally, the bath must be sized to allow movement of the composition around and across the loaded substrate, and such movement may be further enhanced by recirculation and / or ultrasound. The pH of the composition in the bath, the temperature of the bath, and the contact time of the substrate are resulting effective variables that must always be monitored manually or automatically whenever possible.

[0061] As used herein, "inorganic acid" refers to an acid derived from one or more inorganic compounds. Inorganic acids are not organic, and all inorganic acids release hydrogen ions when dissolved in water.

[0062] As used herein, “phosphoric acid” refers to an ortho-phosphoric acid having the chemical formula H3PO4, which is typically available as an aqueous solution having a concentration of up to 75 wt% H3PO4. As used herein, “phosphonic acid” refers to a phosphoric oxo acid having the chemical formula H3PO3, which consists of a single pentavalent phosphorus covalently bonded to a single hydrogen and two hydroxyl groups through single bonds and to oxygen through a double bond.

[0063] As used herein, the term "α-hydroxycarboxylic acid" means a carboxylic acid in which at least one hydroxyl functional group occupies the α-position on the acid (a carbon adjacent to the carboxylic acid functional group). The presence of hydroxyl groups occupying positions within the molecule other than the α-position on the acid is not excluded. If present, the α-hydroxycarboxylic acid is included in the composition in the form of a free acid.

[0064] As used herein, "basicity" refers to the quality of being a base rather than an acid. More specifically, according to the Lewis theory of acids and bases, a base is an electron pair donor. This definition includes, but is not limited to, Brønsted-Lowry bases, which are compounds that act as proton acceptors.

[0065] Water intended herein to be used as a (co-)solvent or diluent is intended to mean water with a low solids content as understood by those skilled in the art. The water may be, for example, distilled water, demineralized water, deionized water, reverse osmotic water, boiler condensate, or ultrafiltered water. Tap water may be permitted in certain circumstances.

[0066] As used herein, “solvents” are substances capable of dissolving other substances to form a homogeneous solution; neither the solvent nor the dissolved substance undergoes a chemical change during dissolution. Solvents may be polar or nonpolar. The term “alcoholic solvent” encompasses such solvents, which are any water-soluble mono-alcohols, diols, or polyols that are liquid at 25°C at atmospheric pressure.

[0067] The term "aprotic solvents" refers herein to solvents that do not provide or accept protons. Conversely, "protic solvents" are solvents that can provide or accept protons. As used herein, "polar solvents" refers to solvents having a dielectric constant (ε) greater than 5 when measured at 25°C: this term encompasses both aprotic and protic solvents. The determination of the dielectric constant (ε) is well known in the art and is within the knowledge of those skilled in the art: in such determinations, the use of measured voltages across parallel plate capacitors may be mentioned.

[0068] As used herein, the term “liquids that are immiscible with water” refers to liquids that form a two-phase system with water. In this regard, a particular preference may be made for liquids characterized as being slightly soluble, very slightly soluble, or substantially insoluble in water, and thereby requiring ≥100 ml of water to dissolve 1 g of the named compound at room temperature (https: / / www.sigmaaldrich.com / united-kingdom / technical-services / solubility.html).

[0069] As used herein, “polyol” refers to any compound containing two or more hydroxyl groups: thus, this term is intended to encompass diols, triols, and compounds containing four or more -OH groups.

[0070] As used herein, "C1-C n"alkyl" groups refer to monovalent groups containing 1 to n carbon atoms, i.e., radicals of alkanes, and groups comprising straight-chain and branched organic groups. As such, "C1-C4alkyl" groups refer to monovalent groups containing 1 to 4 carbon atoms, i.e., radicals of alkanes, and groups comprising straight-chain and branched organic groups. Examples of alkyl groups include, but are not limited to: methyl; ethyl; propyl; isopropyl; n-butyl; isobutyl; sec-butyl; and tert-butyl. In the present disclosure, such alkyl groups may be unsubstituted or substituted with one or more halogens. Where applicable to a given moiety (R), the permission for one or more non-halogen substituents within the alkyl group will be mentioned in the specification.

[0071] The terms “alkylene group” refer to groups that are radicals of linear, branched, or cyclic alkanes, which may be substituted or unsubstituted and may be optionally interrupted by at least one heteroatom.

[0072] Terms used in this institution "C1-C n "Hydroxyalkyl" refers to an HO-(alkyl) group having 1 to n carbon atoms, wherein the attachment point of the substituent is through the oxygen atom and the alkyl group is as defined above.

[0073] "Alkoxy group" refers to a monovalent group represented by -OA, where A is an alkyl group: non-limiting examples thereof are methoxy groups, ethoxy groups, and isopropyloxy groups. As used herein, the term "alkoxylated" means comprising at least one alkoxy group.

[0074] As used herein, a “C2-C6 alkenyl” group refers to an aliphatic carbon group containing 2 to 6 carbon atoms and having at least one double bond positioned at any location. The alkenyl group may be straight-chain, branched, or cyclic and may be optionally substituted with one or more halogens. Where applicable to a given moiety (R), the permission for one or more non-halogen substituents within the alkenyl group will be noted in the specification. The term “alkenyl” also encompasses radicals having “cis” and “trans” configurations, or alternatively “E” and “Z” configurations, as recognized by those skilled in the art. However, generally, a preference for unsubstituted alkenyl groups containing 2 to 6 (C2-C6) or 2 to 4 (C2-C4) carbon atoms should be noted. Examples of C2-C6 alkenyl groups are, but are not limited to: ethenyl; 1-propenyl; 2-propenyl; It includes 1-methyl-ethenyl; 1-butenyl; 2-butenyl; 4-methylbutenyl; 1-pentenyl; 2-pentenyl; 3-pentenyl; 4-pentenyl; 4-methyl-3-pentenyl; 1-hexenyl; 3-hexenyl; and 5-hexenyl.

[0075] As used herein, the term "C3-C6 cycloalkyl" refers to an optionally substituted saturated cyclic hydrocarbon having 3 to 6 carbon atoms. In this disclosure, such cycloalkyl groups may be unsubstituted or substituted with one or more halogens. Where applicable to a given moiety (R), the acceptance of one or more non-halogen substituents within the cycloalkyl group will be mentioned in the specification. Exemplary cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl groups.

[0076] As used herein, "C3-C6 cycloalkylene" means a divalent radical formed by the removal of two hydrogen atoms from one or more rings of a cycloalkyl group having three to six carbon atoms.

[0077] As used herein, "C2-C 18 "Alkenyl" refers to hydrocarbyl groups having 2 to 18 carbon atoms and at least one ethylenically unsaturated unit. The alkenyl group may be straight-chain, branched, or cyclic and may be optionally substituted with one or more halogens. Where applicable to a given moiety (R), the permission for one or more non-halogen substituents within the alkenyl group will be noted in the specification. The term "alkenyl" also encompasses radicals having "cis" and "trans" configurations, or alternatively "E" and "Z" configurations, as recognized by those skilled in the art. The above C2-C 20 Examples of alkenyl groups are, but are not limited to:

[0078]

[0079] It includes 1-cyclopent-1-enyl; 1-cyclopent-2-enyl; 1-cyclopent-3-enyl; 1-cyclohex-1-enyl; 1-cyclohex-2-enyl; and 1-cyclohexyl-3-enyl.

[0080] "C6-C" used alone or as part of a larger moiety, as in "aralkyl groups", as used herein. 18"Aryl" groups refer to monocyclic, bicyclic, and tricyclic ring systems in which the monocyclic ring system is aromatic or at least one of the rings in the bicyclic or tricyclic ring system is aromatic. Bicyclic and tricyclic ring systems comprise benzo-fused 2-3-membered carbocyclic rings. In this disclosure, such aryl groups may be unsubstituted or substituted with one or more halogens. Where applicable to a given moiety (R), the acceptance of one or more non-halogen substituents within the aryl group will be noted in the specification. Exemplary aryl groups include: phenyl; (C1-C4)alkylphenyls such as tolyl and ethylphenyl; indenyl; naphthalenyl, tetrahydronaphthyl, tetrahydroindenyl; tetrahydroanthracenyl; and anthracenyl.

[0081] As used herein, "alkylaryl" refers to alkyl-substituted aryl groups, and "substituted alkylaryl" refers to alkylaryl groups having one or more substituents as described above. Also, as used herein, "aralkyl" means an alkyl group substituted with an aryl radical as defined above.

[0082] As used herein, the term "hetero" refers to groups or moietyes containing one or more heteroatoms such as N, O, Si, and S. Thus, for example, "heterocyclic" refers to cyclic groups having N, O, Si, or S as part of a ring structure. "Heteroalkyl," "heterocycloalkyl," and "heteroaryl" moietyes are alkyl, cycloalkyl, and aryl groups as defined above, respectively, containing N, O, Si, or S as part of their structure.

[0083] The term "heterocyclile" refers to a monovalent chain of carbon and heteroatoms, wherein the heteroatoms are selected from N, O, Si or S, and some of these include at least one heteroatom to form a ring.

[0084] The term “substituted” refers to substitution with at least one suitable substituent. For completeness: substituents may be attached to a specified group or moiety at one or more positions; and multiple substitutions are permitted unless otherwise noted. Additionally, the terms “substituted” or “substituted” imply that such substitution follows the permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound that does not undergo spontaneous modification, for example, by rearrangement, cyclization, or removal.

[0085] The term “substantially absent” is intended to mean that a constituent, component, compound, moiety, functional group, element, ion, or similar is not intentionally added to the subject material and is present, at best, only in trace amounts that do not have an (adverse) effect on the desired properties of the material. In relation to compositions, an exemplary trace amount is less than 1,000 ppm by weight of the composition. The term “substantially absent” encompasses embodiments in which a specified compound, moiety, functional group, element, ion, or other similar component is completely absent from the subject material or is not present in any amount measurable by techniques commonly used in the art.

[0086] As used herein, the term "anhydrous" is equivalent to the term "substantially devoid of water." Water is not intentionally added to a given composition and is present, at best, only in trace amounts that do not have an (adverse) effect on the desired properties of the composition. Brief explanation of the drawing

[0087] The present disclosure will be described below together with the following drawings in which the same reference numerals represent the same elements. FIG. 1 illustrates a joined article according to a first embodiment of the present disclosure. FIG. 2 illustrates a joined article according to a second embodiment of the present disclosure. FIG. 3 illustrates a joined article according to a third embodiment of the present disclosure. Specific details for implementing the invention

[0088] A) Joined article

[0089] Articles to be treated with the disbonding solution described above comprise at least one constituent substrate bonded with first and second adhesives. Thus, this encompasses articles comprising a single substrate folded over itself so that one part of the substrate can be bonded to the other part. However, more typically, the bonded article will comprise at least two substrates bonded together by the first and second adhesives.

[0090] The constituent substrate(s) may be selected from the group consisting of: metallic materials; semiconductor materials; polymers including polyesters, polyamides, and rubbers; glass; ceramics; lignocellulose materials including cotton, rayon (viscose), and cellophane; cellulose esters; and mixtures or composites thereof. If the bonded article comprises at least two substrates, the substrates may be identical or different from each other. And, as mentioned above, the present disclosure has specific applicability to the disbonding of articles comprising at least one metallic material as a constituent substrate.

[0091] FIG. 1 illustrates a bonded article (10) according to a first embodiment of the present disclosure. The bonded article (10) comprises a first substrate (11) and a second substrate (12), each having internal surfaces (11a, 12a). A first adhesive layer (20) is provided directly on the internal surface (11a) of the first substrate (11) and has a dry film thickness (d20) of 30 to 500 μm. In important embodiments, the first adhesive layer (20) is obtained by curing a polyurethane-based 2-part (2K) aqueous composition, wherein the aqueous composition comprises: a first part comprising at least one anionic polyurethane polymer having p) (pi) pendant hydroxyl groups; and q) a second part comprising at least one polyisocyanate compound having pendant -NCO groups, wherein the composition is characterized in that the molar ratio of active hydrogen atoms to -NCO groups in the composition is 5:1 to 1:5.

[0092] Interposed between the first adhesive layer (20) and the inner surface (12a) of the second substrate (12) is a second adhesive layer (22), and this layer typically has a dry film thickness (d) of 30 to 1000 μm, for example, 30 to 500 μm. 22 Must possess ).

[0093] There is no particular intention to limit the constituent adhesive of the second adhesive layer (22), but it must be compatible with the first adhesive layer (20). However, as mentioned above, the second adhesive is distinct from the first adhesive and possesses a higher in-layer cohesive strength than the first adhesive when determined by comparative testing of the adhesives under tensile stress applied to their layers. Cohesive strength is closely correlated with the bulk physical properties of the adhesive: in this disclosure, the increased in-layer cohesive strength of the second adhesive may be a result of the increased crosslinking density of the second adhesive compared to the first adhesive. Alternatively or additionally, the second adhesive may have a higher loading of particulate fillers that contribute to the cohesive bond strength compared to the first adhesive.

[0094] In important embodiments, the second adhesive may have an in-layer cohesive strength that is at least 10% greater than the in-layer cohesive strength of the first adhesive. Preferably, the second adhesive may have an in-layer cohesive strength that is at least 15% or at least 20% greater than the in-layer cohesive strength of the first adhesive.

[0095] In an alternative expression not intended to be mutually exclusive with that presented immediately above, the in-layer cohesive strength of the first adhesive may be 2 to 8 MPa, and the in-layer cohesive strength of the second adhesive may be at least 10 MPa, for example, 10 to 100 MPa.

[0096] Exemplary adhesives for which the second adhesive layer (22) may be formed include, but are not limited to, epoxide, acrylate, and polyurethane adhesives. However, a preference may be mentioned for the bonded articles (10) to include polyurethane adhesives—as the second adhesive—and more specifically, polyurethane adhesives selected from water-based polyurethane adhesives, solvent-based polyurethane adhesives, and polyurethane hot melt adhesives.

[0097] In an alternative embodiment illustrated in FIG. 2, the bonded article (10) is provided with two layers (20, 21) of a first adhesive that are in direct contact with the inner surfaces (11a, 12a) of the first (11) and second (12) substrates, respectively. While the specific composition of the two layers (20, 21) may be the same or different, both adhesives must be selected from aqueous polyurethane dispersion adhesives and polyurethane hot melt adhesives. In important embodiments, both adhesive layers (20, 21) must be obtained by curing a polyurethane-based 2-part (2K) aqueous composition as defined herein. Additionally, the dry film thickness (d) of the two layers 20 , d 21 ) may be the same or different, but each must be in the range of 30 to 500 μm. These adhesive layers (20, 21) can be considered as detachable primer layers of the substrates (11, 12). Typically, a dry film thickness (d) of 30 to 1000 μm. 22 A second adhesive layer (22) having ) is interposed between the layers (20, 21) of the first adhesive.

[0098] In an additional embodiment illustrated in FIG. 3, the bonded article (10) is provided with two layers (22, 23) of a second adhesive that are in direct contact with the inner surfaces (11a, 12a) of the first (11) and second (12) substrates, respectively. The specific configurations of the two layers (22, 23) may be the same or different. Additionally, the dry film thickness (d) of the two layers 22 , d 23 ) may be the same or different, but each must be in the range of 30 to 1000 μm. A layer (20) of the first adhesive having a dry film thickness (d22) of 30 to 500 μm is interposed between the layers (22, 23) of the second adhesive.

[0099] In each of these embodiments, the layers (20, 21) of the first adhesive are intended to provide a location where the article (10) can be disassembled when the article (10) is treated with the disassembly solution described herein. Although the configuration of the bonded article (10) in FIG. 3 is operable, the disassembly of the article may still result in a significant amount of residual second adhesive on the substrates (10, 11) after the disassembly operation, and this residue may need to be removed to enable the reuse or recycling of the substrates. For this reason, it is considered desirable to provide layers (20, 21) of the first adhesive that are in direct contact with one or more of the substrates (11, 12).

[0100] The provision of two substrates (11, 12) is illustrated in the drawings for ease of explanation. It will be recognized that the configurations illustrated in FIGS. 1 through 3 can actually be achieved using a single substrate: for example, a single substrate may be subjected to bending, inward curvature, folding, creasing, twisting, or other deformation means to arrange the inner surfaces of distinct parts of the substrate facing each other.

[0101] Additionally, the articles (10) of FIGS. 1 to 3 are simplified. The bonded articles (10) to be processed may be provided in various forms including bonded films, sheets, plates, fibrous nonwoven sheets, fibrous woven sheets, rectangular prisms, spheres, rings, solid cylinders, tubes, and wires: of course, the provision of bonded articles in more complex shaped forms obtained by conventional techniques such as bending, blanking, casting, forging, rolling, welding, and weaving is not excluded.

[0102] As described above, the bonded article of the present disclosure comprises at least one layer (20, 21) of a first adhesive. Without intending to limit the present disclosure, the first adhesive is preferably a polyurethane adhesive selected from aqueous polyurethane dispersion adhesives and polyurethane hot melt adhesives.

[0103] Suitable polyurethane hot melts useful for providing a first adhesive layer are non-reactive thermoplastics comprising: a) a polyisocyanate component; b) a polyol component; and c) a reaction product of optionally a chain extender component. Hot melt polyurethane adhesives must be substantially solvent-free: any solvent used in the reactive manufacturing process can be removed by conventional methods.

[0104] Polyurethane hot melt adhesives are solid at room temperature but meltable above room temperature. Accordingly, polyurethanes are applied as a melt to the surface of a substrate to be coated and are allowed to recrystallize thereon to provide a layer(s) of a first adhesive. In specific embodiments of the present disclosure, polyurethane hot melt adhesives must feature one or both of the following: a melting point of 60 to 180°C, e.g., 80 to 160°C, determined by dynamic mechanical analysis (DMA); and a recrystallization time of less than 10 minutes, e.g., less than 5 minutes, measured by differential scanning calorimetry (DSC). The term “recrystallization time” refers to the amount of time between the melting peak and the recrystallization peak of the polyurethane hot melt adhesive.

[0105] Water-based polyurethane dispersion adhesives may be of the 1-part (1K) or 2-part (2K) type. When the first adhesive is obtained by curing a polyurethane-based 1-part (1K) aqueous composition, the 1-part (1K) composition preferably comprises: an anionic polyurethane polymer having pendant hydroxyl groups; and a blocked polyisocyanate. Before application, such 1-part (1K) compositions must be prepared and stored under conditions that inhibit or prevent the activation of the blocked polyisocyanate. The constituent anionic polyurethane of this type of 1-part (1K) composition may be prepared in the manner described below for the 2-part (2K) aqueous composition.

[0106] 2-part aqueous composition

[0107] In important embodiments, the bonded article of the present disclosure comprises at least one layer (20, 21) of a first adhesive obtained by curing a polyurethane-based 2-part aqueous composition. More specifically, the 2-part (2K) aqueous composition comprises the following:

[0108] p) Part 1 including the following:

[0109] (pi) At least one anionic polyurethane polymer having pendant hydroxyl groups; and,

[0110] q) A second part comprising at least one polyisocyanate compound having pendant -NCO groups,

[0111] The composition is characterized in that the molar ratio of active hydrogen atoms to -NCO groups in the composition is 5:1 to 1:5. The above or each of the anionic polyurethane polymers of the composition should preferably be dilutable with water.

[0112] As mentioned above, it is preferable that a 2-part aqueous composition be used as an aqueous primer composition to form a detachable layer (20, 21) that comes into direct contact with the substrate surface (11a, 12a) upon curing.

[0113] Part pi)

[0114] The preparation of polyurethane dispersions is known as exemplified in US Patent No. 4,237,264; US Patent No. 4,408,008; US Patent No. 5,569,706; US Patent Publication No. 2004204559; US Patent Publication No. 2005004367; GB Patent Publication No. 2386898; and WO Publication No. 2005023947.

[0115] Alternatively, and as is known in the art, suitable polyurethanes may be obtained from the reaction of: i) at least one polyol; ii) optionally additional active hydrogen compounds; and iii) at least one polyisocyanate compound. To ensure that the polyurethane does not have pendant isocyanate (NCO) groups, the equivalents of the active hydrogen atoms to the NCO groups of the reactants must be selected to ensure that no free NCO groups are present in the polyurethane: thus, the molar ratio of active hydrogen atoms to isocyanate functional groups must be at least 1:1, e.g., 1.1:1 to 3:1 or 1.1:1 to 2:1.

[0116] As used herein, “polyol” refers to any compound comprising two or more hydroxyl groups: thus, this term is intended to encompass diols, triols, and compounds containing four or more -OH groups. Additionally, at least one reactant polyol must be selected from the group consisting of: polyester polyols; polyether polyols; and polycarbonate polyols. The polyol must preferably have a number average molecular weight (Mn) of 1,000 to 50,000 g / mol, e.g., 1,000 to 25,000 g / mol. Alternatively or in addition to this molecular weight characterization, the hydroxyl number of the reactant polyol must preferably be 20 to 850 mg KOH / g, e.g., 25 to 500 mg KOH / g.

[0117] Polycarbonate diols can be obtained by reacting carbonate derivatives with diols. Exemplary carbonate derivatives are diphenyl carbonate, di(C1-C6)alkyl carbonates, and diaryl carbonates including but not limited to phosgene. Exemplary diols include, but are not limited to: ethylene glycol; 1,2-propanediol; 1,3-propanediol; 1,3-butanediol; 1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol; cyclohexanedimethanol; diethylene glycol; dipropylene glycol; neopentyl glycol; and mixtures thereof.

[0118] Polyester diols can be obtained by reacting the diols with aliphatic, aromatic, or alicyclic dicarboxylic acids, or, in some cases, any one of their corresponding anhydrides: the reaction may optionally take place in the presence of an esterification catalyst. Examples of suitable dicarboxylic acids include, but are not limited to: adipic acid; glutaric acid; pimelic acid; souveric acid; nonandic acid; decandic acid; succinic acid; maleic acid; sebacic acid; azelaic acid; terephthalic acid; isophthalic acid; o-phthalic acid; tetrahydrophthalic acid; hexahydrophthalic acid; trimellitic acid; and 1,4-cyclohexanedicarboxylic acid. Examples of suitable anhydrides include succinic anhydride, o-phthalic anhydride, and trimellitic anhydride. It is noted that various commercially available dimeric fatty acids in saturated (hydrogenated) or unsaturated forms can also be used as dicarboxylic acids. And examples of suitable diols for the manufacture of polyester diols are: ethanediol; di-, tri-, or tetraethylene glycol; 1,2-propanediol; di-, tri-, tetrapropylene glycol; 1,3-propanediol; 1,4-butanediol; 1,3-butanediol; 2,3-butanediol; 1,6-hexanediol; 1,5-pentanediol; 2,2-dimethyl-1,3-propanediol (neopentyl glycol); 1,4-dihydroxycyclohexane; 1,4-dimethylcyclohexane; 1,8-octanediol; 1,10-decanediol; 1,12-decanediol; 2,2,4- and / or 2,4,4-trimethyl-1,3-pentanediol; and mixtures thereof.

[0119] Other useful polyester diols are those that can be obtained from the diol-initiated polymerization of hydroxycarboxylic acids containing 2 to 12 carbon atoms or their lactones. The hydroxycarboxylic acids may be saturated or unsaturated, linear or branched, and examples of these include: glycolic acid; lactic acid; 5-hydroxyvaleric acid; 6-hydroxycaproic acid; ricinoleic acid; 12-hydroxystearic acid; 12-hydroxydodecanic acid; 5-hydroxydodecanic acid; 5-hydroxydecanoic acid; and 4-hydroxydecanoic acid. Examples of suitable lactones are β-propiolactone, δ-valerolactone, (C1-C6)alkyl-valerolactone, ε-caprolactone, and (C1-C6)alkyl-ε-caprolactone.

[0120] Apart from the above, in certain embodiments, the polyol from which the polyurethane is derived is a polyether polyol, in particular a polyether polyol having a polydispersity (PD) of less than 2, preferably less than 1.5, more preferably less than 1.3. For the sake of completeness, "polyether" is understood for the purposes of this disclosure as a polymer in which the repeating unit contains ether functional groups COC within the main chain. Thus, polyacetals as well as polymers having lateral ether groups, such as cellulose ethers, starch ethers, and vinyl ether polymers, are not included in this definition. Preferably, the polyether polyol is a polyoxyalkylene, in particular a polyoxy(C2-C3)alkylene.

[0121] In particular, as described in US Patent No. 3,905,929 and US Patent No. 3,920,598, the presence of polyoxy(C2-C3)alkylene chains in the reactant polyol can serve to internally stabilize the polyurethane in the dispersion. This can minimize or eliminate the need to include emulsifiers in the dispersion to provide external stabilization of the polyurethane.

[0122] It is noted that at least one monol can be used as an additional active hydrogen reactant when synthesizing polyurethane in some embodiments. For example, monofunctional hydrophilic polyoxyalkylenes, such as polyoxyethylene or polyoxypropylene, can be introduced into the polyurethane as a means of modifying the properties of the latex and improving its ease of emulsion formation. Where present, the monol is present in an amount of 0.1 to 5 weight percent based on the weight of reactants i) to iii).

[0123] To make the resulting polyurethane anionic and, where applicable, water-dispersible, the polymer is typically functionalized with at least one functional group selected from: carboxylic acid groups; anhydride groups; sulfonic acid groups; or phosphate groups. These functional groups may be incorporated into the polyurethane by post-functionalization of urethane bonds obtained from the reaction of polyol(s) and polyisocyanate(s). More typically, these functional groups are introduced using functionalized reactant polyols, wherein the functional groups are (sterically) inhibited from reacting with -NCO groups when yielding the polyurethane. Exemplary reactant diols are, but are not limited to: dimethylolpropionic acid (DMPA); 2,2-di(hydroxymethyl)acetic acid; 2,2,2-tri(hydroxymethyl)acetic acid; 2,2-di-(-hydroxymethyl)propionic acid; It includes 2,2-di(hydroxymethyl)butyric acid; 2,2-di(hydroxymethylpentanoic acid); 2,4-dihydroxybenzoic acid; trimellitic anhydride (TMA); and sodium 4,4-dihydroxy-l-butanesulfonate.

[0124] As used herein, "polyisocyanate" means a compound comprising at least two -N=C=O functional groups. Polyisocyanates suitable for inducing hydroxyl-functional polyurethanes are also those described herein in relation to part q) of an aqueous 2-part composition.

[0125] To facilitate their inclusion into the compositions of the present disclosure, at least one polyurethane may initially be provided as a dispersion, and the particles of the dispersion, when measured by dynamic light scattering, are less than 1 micron, for example, 50 to 400 nm. 50 It is desirable to be able to feature a unimodal particle size distribution having particle size.

[0126] The formation of a polyurethane dispersion in water can be achieved by: i) first forming a prepolymer having free NCO groups from the reactants under anhydrous conditions or in the presence of an organic solvent; and ii) dispersing the prepolymer in an aqueous phase in either a continuous process towed by a High Internal Phase Ratio (HIPR) process or a batch process towed by a reverse phase process. Reaction i) can be carried out under a catalyst and at a temperature, for example, of 25 to 100°C. The resulting prepolymer preferably features at least one of the following: i) an NCO content of 5 to 30%, preferably 10 to 25% by weight, based on the weight of the prepolymer; and ii) an NCO functional value of 2.2 to 3.0, preferably 2.2 or 2.4 to 2.9. iii) viscosity of 300 to 35,000 mPa·s at 20°C, preferably 1,000 to 10,000 mPa·s; and iv) number average molecular weight (Mn) of 500 to 30,000, e.g., 500 to 15,000 or 500 to 10,000 g / mol. For completeness, these characteristics i) to iv) are not intended to be mutually exclusive: in practice, the prepolymer may satisfy one, two, three, or four of these stated characteristics.

[0127] Standard polyurethane catalysts known in the art include: primary tin salts of carboxylic acids such as stannus octoate, stannus oleate, stannus acetate, and stannus laurate; dialkyltin dicarboxylates such as dibutyltin dilaurate and dibutyltin diacetate; tertiary amines; alkanolamine compounds; 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine; tetraalkylammonium hydroxides; alkali metal hydroxides; alkali metal alcoholates; tin alkoxides such as dibutyltin dimethoxide, dibutyltin diphenoxide, and dibutyltin diisopropoxide; tin oxides such as dibutyltin oxide and dioctyltin oxide; reaction products of dibutyltin oxides and phthalic acid esters; tin mercaptides; alkyl titanates; Organoaluminum compounds such as aluminum trisacetylacetonate, aluminum trisethylacetoacetate, and diisopropoxyaluminum ethylacetoacetate; chelate compounds such as zirconium tetraacetylacetonate and titanium tetraacetylacetonate; organosilicon titanium compounds; bismuth tris-2-ethylhexanoate; acid compounds such as phosphoric acid and p-toluenesulfonic acid; triphenylborane; triphenylphosphine; 1,8-diazabicyclodec-7-ene (DBU); 1,5-diazabicyclo[4.3.0]non-5-ene; 1,4-diazabicyclo[2.2.2]octane; 4-dimethylaminopyridine; 1,5,7-triazabicyclo[4.4.0]dec-5-ene; It includes 7-methyl-1,5,7-triazabicyclo[4.4.0]dek-5-ene; 1,8-bis(tetramethylguanidino)naphthalene; and 2-tert-butyl-1,1,3,3-tetramethylguanidine. Depending on the properties of the isocyanate, the amount of catalyst used is typically in the range of 0.005 to 10% based on the weight of the mixture being catalyzed.

[0128] As mentioned, the prepolymer may optionally be prepared in the presence of a solvent, and the solvent may be removed at least partially and preferably entirely before or after the formation of the aqueous dispersion. If a solvent is used, examples of solvents that do not react with the isocyanate include: ketones such as acetone and butanone; ethers such as tetrahydrofuran, dioxane, and dimethoxyethane; ether esters such as methoxypropyl acetate; (cyclic) amides such as dimethylformamide and dimethylacetamide and ureas; N,N'-dimethyl-2,5-dizapentanone; N-methylpyrrolidone; and capped glycol ethers. Such solvents may be added at any stage of the preparation of the prepolymer.

[0129] The above prepolymers are preferably extended with a chain extender. As is known to those skilled in the art, typical chain extenders have a weight-average molecular weight (Mw) of 18 to 500 g / mol and have at least two active hydrogen-containing groups. In particular, polyamines and / or water may be used as chain extenders, and a mixture of water and polyamines is particularly preferred. Exemplary polyamines that may be used alone or in combination include: aminated polypropylene glycols such as Jeffamine D-400 available from Huntsman Chemical Company; hydrazine; piperazine; aminoethylpiperazine; 2-methylpiperazine; 1,5-diamino-3-methylpentane; isophorone diamine; ethylenediamine; diaminobutane; hexanediamine; hexamethylenediamine; tetramethylenetetraamine; aminoethylpropyltrimethoxysilane; diethylenetriamine; triethylenetetramine; triethylenepentamine; ethanolamine; and lysine may be mentioned.

[0130] - When a chain extender other than water is used as a dispersion medium to produce the anionic polyurethane polymers of the present disclosure, the equivalent of active hydrogen provided by the chain extender to the NCO groups of the prepolymer must be selected to ensure that no free NCO groups are present in the final polyurethane (pi) as described above.

[0131] Anionic polyurethanes (pi)) may be partially neutralized, completely neutralized, or even over-neutralized with inorganic or organic bases. Exemplary bases include: amine bases as identified herein; alkali metal hydroxides; ammonia; and phosphines. The degree of neutralization of the anionic functional groups of the polyurethane may be 0 to 150%, e.g., 25 to 125% or 50 to 100%. A degree of neutralization exceeding 100% indicates the presence of a stoichiometric excess of basic functional groups relative to the anionic groups.

[0132] Polyurethanes suitable for use in this invention are commercially available, examples of which include Dispercoll U56, available from Covestro AG.

[0133] Part q) Polyisocyanate-containing curing agent

[0134] The second part of the aqueous composition comprises at least one polyisocyanate compound having pendant -N=C=O (hereinafter -NCO) groups that act as a crosslinking agent through reaction with the pendant hydroxyl groups provided by the first part of the composition. It is not excluded that the composition may include blocked isocyanates as a supplementary crosslinking agent for the polyisocyanate compound(s) having pendant -NCO groups. However, the use of such blocked polyisocyanate co-crosslinking agents is undesirable, and accordingly, in certain embodiments, the composition may be characterized as being substantially free of said blocked isocyanates.

[0135] The 2-part (2K) aqueous composition may comprise polyisocyanates in amounts characterized by a molar ratio of active hydrogen atoms to -NCO groups of 5:1 to 1:5, for example, 3:1 to 1:3 or 2:1 to 1:2. For certainty, the term "-NCO groups" includes blocked -NCO groups included in the molar ratio term.

[0136] The polyisocyanate will comprise at least two -NCO functional groups, for example, two to five or two to four -NCO functional groups. Suitable polyisocyanates include aliphatic, alicyclic, aromatic, and heterocyclic isocyanates, their dimers and trimers, and mixtures thereof.

[0137] Aliphatic and alicyclic polyisocyanates may comprise 6 to 100 carbon atoms that are linked in a straight chain or cyclized and have at least two isocyanate reactive groups. Examples of suitable aliphatic isocyanates include, but are not limited to, ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, 1,6,11-undecane triisocyanate, 1,3,6-hexamethylene triisocyanate, bis(isocyanatoethyl)-carbonate, and bis(isocyanatoethyl) ether. Exemplary alicyclic polyisocyanates are, but are not limited to, dicyclohexylmethane 4,4'-diisocyanate (H 12It includes MDI), 1-isocyanatomethyl-3-isocyanato-1,5,5-trimethyl-cyclohexane (isophorone diisocyanate, IPDI), cyclohexane 1,4-diisocyanate, hydrogenated xylylene diisocyanate (H6XDI), 1-methyl-2,4-diisocyanato-cyclohexane, m- or p-tetramethylxylene diisocyanate (m-TMXDI, p-TMXDI), and dimeric fatty acid diisocyanates.

[0138] The term “aromatic polyisocyanate” is used herein to describe organic isocyanates in which isocyanate groups are directly attached to ring(s) of mononuclear or polynuclear aromatic hydrocarbon groups. In turn, mononuclear or polynuclear aromatic hydrocarbon groups refer to cyclic hydrocarbon moiety that is essentially planar of conjugated double bonds, which may be a single ring or may comprise multiple condensed (fused) or covalently linked rings. The term aromatic also includes alkylaryl. Typically, the hydrocarbon (main) chain contains 5, 6, 7, or 8 main chain atoms within a single cycle. Examples of such planar cyclic hydrocarbon moietyes include, but are not limited to, cyclopentadienyl, phenyl, naphthalenyl-,

[10] annulenyl-(1,3,5,7,9-cyclodecapentaenyl-),

[12] annulenyl-, [8]annulenyl-, phenalene (perinaphthene), 1,9-dihydropyrene, and chrysene (1,2-benzophenanthrene). Examples of alkylaryl moietyes are benzyl, phenethyl, 1-phenylpropyl, 2-phenylpropyl, 3-phenylpropyl, 1-naphthylpropyl, 2-naphthylpropyl, 3-naphthylpropyl, and 3-naphthylbutyl.

[0139] Exemplary aromatic polyisocyanates are, but are not limited to: all isomers of toluene diisocyanate (TDI) in isomerically pure form or as a mixture of several isomers; naphthalene 1,5-diisocyanate; diphenylmethane 4,4'-diisocyanate (MDI); diphenylmethane 2,4'-diisocyanate and mixtures of diphenylmethane 4,4'-diisocyanate and 2,4'-isomers or mixtures thereof with higher functional oligomers (so-called crude MDI); xylylene diisocyanate (XDI); diphenyl-dimethylmethane 4,4'-diisocyanate; di- and tetraalkyl-diphenylmethane diisocyanates; dibenzyl 4,4'-diisocyanate; phenylene 1,3-diisocyanate; It includes phenylene 1,4-diisocyanate.

[0140] If necessary, polyisocyanates may be biuretized, allophanated, and / or isocyanurated by generally known methods such as those described in UK Patent No. 889,050. At use, such derivatives may be substantially free of the parent diisocyanate: the derivatives may have been separated from any excess of the parent diisocyanate by ordinary means including but not limited to distillation.

[0141] Additionally, the term “polyisocyanate” is intended to encompass prepolymers formed by partially reacting the aliphatic, alicyclic, aromatic, and heterocyclic isocyanates with polyols such as polyether polyols or polyester polyols, thereby providing isocyanate-functional oligomers, which may be used alone or in combination with free isocyanate(s). However, it is preferred herein that part q) contains less than 5 weight percent of the prepolymers based on the weight of the part. For example, part q) may contain less than 1 weight percent of the prepolymers based on the weight of the part, or the prepolymers may be substantially absent.

[0142] Additives and auxiliary agents of the compositions of the first adhesive

[0143] Compositions providing the first adhesive of the present disclosure—as exemplified by the 2-part (2K) aqueous composition—will typically further include adjuvants and additives capable of imparting improved properties to these compositions. For example, adjuvants and additives may impart one or more of: improved adhesion to substrates; reduced corrosiveness to substrate surfaces; improved elastic properties; improved elastic recovery; longer possible processing time; faster curing time; lower residual tackiness; and improved leveling. Included in such adjuvants and additives are: adhesion promoters; corrosion inhibitors; catalysts; curing retardants; surfactants, wherein a preference for nonionic surfactants may be noted; wetting agents; plasticizers; stabilizers; reinforcing agents; rheology control agents; biocides; flame retardants; colorants; organic cosolvants; and non-reactive diluents.

[0144] Such auxiliary agents and additives may be used in any combination and proportion as long as they do not adversely affect the properties and essential characteristics of the composition. Although exceptions may exist in some cases, these auxiliary agents and additives should not constitute more than 50 weight percent of the total composition as a whole, and preferably not more than 20 weight percent of the composition.

[0145] For completeness, it is noted that auxiliary materials and additives containing reactive groups are generally blended into the appropriate part of the 2-part (2K) composition to ensure their storage stability. Non-reactive materials may be formulated into either or both of the two parts.

[0146] Water-based polyurethane dispersion adhesives—as exemplified by the above 2-part (2K) compositions—may comprise one or more catalysts for the reaction of -NCO groups with active hydrogen compounds. Standard catalysts known in the art include: primary tin salts of carboxylic acids such as stannus octoate, stannus oleate, stannus acetate, and stannus laurate; dialkyltin dicarboxylates such as dibutyltin dilaurate and dibutyltin diacetate; tertiary amines; alkanolamine compounds; 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine; tetraalkylammonium hydroxides; alkali metal hydroxides; alkali metal alcoholates; tin alkoxides such as dibutyltin dimethoxide, dibutyltin diphenoxide, and dibutyltin diisopropoxide; Tin oxides such as dibutyltin oxide and dioctyltin oxide; reaction products of dibutyltin oxides and phthalic acid esters; tin mercaptides; alkyl titanates; organoaluminum compounds such as aluminum tris-acetylacetonate, aluminum tris-ethylacetoacetate, and diisopropoxyaluminum ethylacetoacetate; chelate compounds such as zirconium tetraacetylacetonate and titanium tetraacetylacetonate; organosilicon titanium compounds; bismuth tris-2-ethylhexanoate; acid compounds such as phosphoric acid and p-toluenesulfonic acid; triphenylborane; triphenylphosphine; 1,8-diazabicyclodec-7-ene (DBU); 1,5-diazabicyclo[4.3.0]non-5-ene; 1,4-diazabicyclo[2.2.2]octane; It comprises 4-dimethylaminopyridine; 1,5,7-triazabicyclo[4.4.0]dek-5-en; 7-methyl-1,5,7-triazabicyclo[4.4.0]dek-5-en; 1,8-bis(tetramethylguanidino)naphthalene; and 2-tert-butyl-1,1,3,3-tetramethylguanidine. Depending on the properties of the polyisocyanate, the amount of catalyst used in the 2-part (2K) composition is typically in the range of 0.005 to 2% by weight of the composition.

[0147] The addition of specific additives can promote the adhesion of the first adhesive composition to specific substrates. For example, in an embodiment, the 2-part (2K) aqueous composition may contain 0 to 5 weight%, e.g. 0.5 to 5 weight%, of an adhesion promoter based on the weight of the composition. Exemplary adhesion promoters are, but are not limited to: morin (2-(2,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-1-coumarone-4-ketone); 3,7-dihydroxy-2-naphthoic acid (3,7-dihydroxynaphthalene-2-carboxylic acid); pyrogallol carboxylic acid (2,3,4-trihydroxybenzoic acid); 3,4-dihydroxy-benzeneguanidine-acetic acid; gallic acid (3,4,5-trihydroxybenzoic acid); para-aminosalicylic acid (4-amino-2-hydroxybenzoic acid, PAS); Flutter acid (4,4'-methylene-bis(3-hydroxy-2-naphthoic acid)); and citric acid (2-hydroxypropane-1,2,3-tricarboxylic acid) are included. Among these compounds, a preference for the use of citric acid, gallic acid, and especially para-aminosalicylic acid (PAS)—alone or in combination—may be mentioned.

[0148] A corrosion inhibitor may be included in the first adhesive in an amount of up to 5 weight percent based on the weight of the adhesive. For example, in an embodiment, the 2-part (2K) aqueous composition may contain 0.1 to 2 weight percent, e.g. 0.1 to 1 weight percent, of a corrosion inhibitor based on the weight of the composition. Exemplary corrosion inhibitors that may be present in the composition alone or in combination include salts of alkali metals, alkaline earth metals, and transition metals such as titanium, chromium, and zinc. Those that may be mentioned are: magnesium oxide, magnesium hydroxide; magnesium carbonate; magnesium phosphate; magnesium silicate; zinc oxide; zinc hydroxide; zinc carbonate; zinc phosphate; and zinc silicate.

[0149] Exemplary reinforcing agents may be selected from: epoxy-elastomer adducts; and reinforcing rubber in the form of dispersed core-shell particles that do not possess pendant reactive groups. In certain embodiments, reinforcing agents may be included in the 2-part (2K) aqueous composition in an amount of up to 10 weight percent based on the weight of the composition.

[0150] It will be understood that polyurethane polymers may provide all of the film-forming polymers of the aqueous polyurethane dispersions, as exemplified by the 2-part (2K) aqueous composition. However, the presence of additional film-forming resins is not excluded. For example, the 2-part (2K) aqueous composition may, in certain embodiments, comprise one or more supplementary film-forming resins in an amount of up to 25 weight percent as a whole, based on the solid content of the composition. Any such supplementary film-forming resins included in the first adhesive may be thermosetting or thermoplastic, but must be dispersible, emulsifiable, or soluble in water.

[0151] Optionally, the rheology control agent useful in the first adhesive may include fillers, thickeners, and combinations thereof. The total amount of rheology control agent in the first adhesive should generally not exceed 10 weight percent based on the weight of the adhesive. For example, a 2-part (2K) aqueous composition may contain 0 to 5 weight percent, 0 to 2 weight percent, or even 0 to 1 weight percent of rheology control agent based on the weight of the composition.

[0152] Exemplary thickeners include, but are not limited to: clay-based thickeners such as organoclays; polysaccharides such as guar and xanthan; polyacrylates; and associative thickeners. In particular, the use of cellulose or cellulose derivatives as polysaccharide thickeners may be mentioned, for example: carboxymethylcellulose; methylcellulose; hydroxyethylcellulose; hydroxyethylmethylcellulose; hydroxypropylmethylcellulose; cellulose nanofibers; and cellulose nanocrystals.

[0153] Broadly speaking, there is no particular intention to limit the shape of the particles used as fillers: needle-shaped, spherical, ellipsoidal, cylindrical, bead-shaped, cubic, or plate-shaped particles may be used alone or in combination. Additionally, aggregates of more than one particle type are expected to be used. Likewise, there is no particular intention to limit the size of the particles used as fillers. However, such fillers typically have a d of 0.1 to 1500 μm, e.g., 1 to 1250 μm, when measured by dynamic light scattering. 50 It will have a particle size.

[0154] Exemplary fillers include, but are not limited to, calcium carbonate, calcium oxide, calcium hydroxide (lime powder), precipitated and / or pyrogenic silica, zeolites, bentonites, wollastonite, magnesium carbonate, diatomite, barium sulfate, aluminum oxide, aluminum silicate, clay, talc, titanium oxide, iron oxide, zinc oxide, sand, quartz, flint, mica, glass beads, glass powder, and other ground mineral materials. Organic fillers may also be used, in particular wood fibers, wood flour, sawdust, cellulose, cotton, pulp, cotton, wood chips, chopped straw, chaff, ground walnut shells, and other chopped fibers may be used. Short fibers such as glass fibers, glass filaments, polyacrylonitrile, carbon fibers, Kevlar fibers, or polyethylene fibers may also be added.

[0155] If present, pyrogenic and / or precipitated silica is preferably 10 to 90 m 2 They must have a BET specific surface area of ​​ / g. When used, they do not cause any additional increase in the viscosity of the composition according to the present disclosure, but contribute to strengthening the cured composition.

[0156] Higher BET specific surface area, advantageously 100 to 250 m² 2 It can be likewise considered that exothermic and / or precipitated silica having / g can be used as a filler: due to the larger BET surface area, the reinforcing effect of the hardened composition is achieved with a smaller weight percentage of silicic acid.

[0157] Also suitable as fillers are hollow spheres having a mineral shell or a plastic shell. These may be, for example, hollow glass spheres commercially available under the trade name Glass Bubbles®. Plastic-based hollow spheres such as Expancel® or Dualite® may be used and are described in EP 0 520 426 B1: these are made of inorganic or organic materials and each have a diameter of 1 mm or less, preferably 500 μm or less.

[0158] Fillers that impart thixotropy to a composition may be desirable for many applications: such fillers are also described as rheology aids, e.g., hydrogenated castor oil, fatty acid amides, or swelling plastics such as PVC.

[0159] For the purposes of this disclosure, a “plasticizer” is a substance that reduces the viscosity of a composition and thus facilitates its processability. In this invention, the plasticizer may constitute up to 10 weight percent or up to 5 weight percent based on the weight of the adhesive. For example, a 2-part (2K) aqueous composition may contain 0 to 5 weight percent or 0 to 2 weight percent of a plasticizer based on the weight of the composition. Suitable plasticizers are preferably: diurethanes; Cetiol OE (Cognis Deutschland GmbH, D Monofunctional, linear, or branched C4-C (available from sseldorf) 16It is selected from the group consisting of ethers of alcohols; esters of abietic acid, butyric acid, thiobutyric acid, acetic acid, propionic acid, and citric acid; esters based on nitrocellulose and polyvinyl acetate; fatty acid esters; dicarboxylic acid esters; esters of OH-group-retaining or epoxidized fatty acids; glycolic acid esters; benzoic acid esters; phosphate esters; sulfonic acid esters; trimellitic acid esters; polyether plasticizers such as terminal-capped polyethylene or polypropylene glycols; polystyrene; hydrocarbon plasticizers; chlorinated paraffins; and mixtures thereof. In principle, phthalic acid esters may be used as plasticizers, but it is noted that they are undesirable due to their toxicological potential.

[0160] For the purposes of this disclosure, "stabilizers" should be understood as antioxidants, UV stabilizers, heat stabilizers, or hydrolysis stabilizers. In this disclosure, the stabilizers may constitute up to 10 weight percent or up to 5 weight percent based on the total weight of the first adhesive as a whole. For example, a 2-part (2K) aqueous composition may contain 0 to 5 weight percent or 0 to 2 weight percent of stabilizers based on the weight of the composition. Standard commercial examples of stabilizers suitable for use in this disclosure include: sterically hindered phenols; thioethers; benzotriazoles; benzophenones; benzoates; cyanoacrylates; acrylates; amines of the hindered amine light stabilizer (HALS) type; phosphorus; sulfur; and mixtures thereof.

[0161] As used herein, the term “colorant” refers to any substance that imparts one or more of color, opacity, or visual effects to a composition. Visual effects that may be imparted to a composition by a colorant, either in addition to or independently of color, include: reflectance; pearlescent; gloss; texture; phosphorescence; fluorescence; photochromic; photosensitive; thermochromic; and goniochromism. The term “colorant” is intended to encompass: organic pigments; inorganic pigments; dyes; and tints. More than one colorant may be included in the composition, and each added colorant is considered to be independently added in any suitable form in which separate particles, dispersions, and solutions may be referred to.

[0162] As mentioned above, polyurethane dispersion adhesives—of which 2-part (2K) aqueous compositions are important examples—are aqueous and thus contain mainly water as a solvent or as a continuous phase of the dispersion. However, in certain embodiments, the first adhesive is obtained from a polyurethane-based 1-part (1K) or 2-part (2K) aqueous composition, and the composition further comprises organic cosolvants and / or non-reactive diluents where they can usefully control the viscosity of the composition. Exemplary cosolvants and non-reactive diluents are, but are not limited to: aromatic solvents such as xylene, toluene, and cumene; ethylene glycol dimethyl ether; ethylene glycol diethyl ether; ethylene glycol dibutyl ether; ethylene glycol diphenyl ether; diethylene glycol; diethylene glycol-monomethyl ether; diethylene glycol-monoethyl ether; Ether solvents such as diethylene glycol-mono-n-butyl ether; diethylene glycol dimethyl ether; diethylene glycol diethyl ether; diethylene glycol di-n-butylyl ether; propylene glycol butyl ether; propylene glycol phenyl ether; dipropylene glycol monomethyl ether; dipropylene glycol dimethyl ether; dipropylene glycol di-n-butyl ether; petroleum fractions such as naphtha and Solvesso® products (available from Exxon); acetates including glycol ether acetates; propionates such as ethyl 3-ethoxypropionate; adipates; sebacates; phthalates; benzoates; organic phosphoric acid or sulfonic acid esters; and sulfonamides.

[0163] Apart from the above, it is preferable that the above non-reactive diluents and co-solvents constitute less than 5% by weight, particularly less than 2% by weight, based on the total weight of the polyurethane-based 2-part (2K) aqueous composition described above.

[0164] Formation of a 2-part (2K) aqueous composition

[0165] 2-part (2K) aqueous compositions are formulated by a simple mixing of various components as well as any auxiliary components. The order of mixing the components is not intended to be limited, but it may be wise to first form an aqueous dispersion of polyurethane before mixing additional components. In this scenario, the aqueous dispersions of polyurethane may be prepared with, for example, a solid content of 20 to 60 weight% or 30 to 60 weight% each.

[0166] If necessary, the 2-part (2K) aqueous composition may be prepared well prior to its application. However, in an interesting alternative embodiment, a concentrated composition may first be obtained by mixing the components with only a portion of the water present in the applied aqueous composition: then the concentrated composition may be diluted with the remaining water immediately before application. Such concentrated compositions are considered to be prepared and stored as single-package concentrates that can be converted by dilution with water alone, or as multi-part concentrates that must be combined and diluted in two or more to form a complete working composition according to the present disclosure. Any dilution may be performed simply by adding water, particularly deionized and / or demineralized water, under mixing. The composition may be prepared in an equivalent rinse stream in which streams of one or more concentrates are injected into a continuous stream of water.

[0167] Without a specific intention to limit the amount of water included in the compositions, water-based compositions preferably contain 5 to 50 weight percent, preferably 5 to 40 weight percent, of water based on the weight of the composition. In an alternative but non-mutually exclusive characterization, the composition may be defined as having a viscosity of 0.1 to 10 Pa.s, e.g., 0.5 to 5 Pa.s, when measured using a Brookfield viscometer at 25°C.

[0168] Methods for forming joined articles

[0169] Most broadly, bonded articles are formed by: applying layers of the first and second adhesives to two distinct surfaces of a substrate or substrates; and bringing the applied adhesive layers into contact with surfaces disposed between them under pressure to form a bond.

[0170] An adhesive composition that will provide a first adhesive layer (20, 21)—e.g., the polyurethane-based 2-part (2K) water-based composition described above—is applied to the substrate surface(s) and then cured or solidified in situ. Before applying the compositions, it is often recommended to pretreat the relevant surfaces. Any such pretreatment should include: cleaning the surface(s); abrading the surface(s); and at least one of applying an anti-corrosion coating or applying a conversion coating or conversion treatment thereto.

[0171] Cleaning serves to remove foreign substances from the surface. Cleaning treatments are known in the art and may be performed in a single or multi-stage manner consisting of, for example: etching treatment using an acid suitable for the substrate and optionally an oxidizing agent; ultrasonic treatment; plasma treatment including chemical plasma treatment, corona treatment, atmospheric plasma treatment, and flame plasma treatment; immersion in an aqueous alkaline degreasing bath; treatment with an aqueous cleaning emulsion; treatment with a cleaning solvent such as carbon tetrachloride or trichloroethylene; and preferably, water rinsing using deionized or deionized water. When an aqueous alkaline degreasing bath is used, any degreasing agent remaining on the surface should preferably be removed by rinsing the substrate surface with deionized or deionized water.

[0172] The terms "transition coating" and "transition treatment" refer to a treatment of a substrate surface that causes the surface material of the substrate to be chemically converted into a different material. Typically, a metal or alloy surface exhibiting defect regions is chemically converted to provide a firmly bonded coating consisting wholly or partially of a stabilized form of the substrate metal—e.g., an oxidized form. Such chemical conversion coatings can demonstrate high corrosion resistance as well as provide strong bonding affinity for subsequent coating layers.

[0173] The compositions are then applied to substrate surfaces preferably pretreated by conventional application methods such as brushing; roll coating; doctor-blade application; printing methods; and spray methods including, but not limited to, air-spray spraying, air-assisted spraying, airless spraying, and high-volume low-pressure spraying.

[0174] The first adhesive compositions—as exemplified by the 2-part (2K) water-based compositions—are recommended to be applied to the surface with a wet film thickness of 10 to 1000 μm, for example, 10 to 750 μm. Within this range, the application of thinner layers is more economical and reduces the possibility of harmful thick cured areas. However, great control must be exercised when applying thinner coatings or layers to avoid the formation of discontinuous cured films.

[0175] Curing of the applied aqueous compositions of the present disclosure typically occurs at temperatures ranging from 20°C to 120°C, preferably from 20°C to 120°C, particularly from 20°C to 80°C. Suitable temperatures depend on the specific compounds present and the desired drying and curing rates, and can be determined on an individual case by a skilled technician using simple preliminary tests if necessary. Of course, drying and curing at lower temperatures within these ranges is advantageous as it eliminates the need to substantially heat or cool the mixture from the generally prevailing ambient temperature. However, where applicable, the temperature of the mixture formed from each element of the composition may be raised above the mixing temperature and / or application temperature using conventional means including microwave induction, ovens, and drying booths. To ensure complete curing, the raised temperature may be maintained for up to 60 minutes.

[0176] The coating method of the present disclosure may further include reducing the oxygen content in the environment of the curing material: this may be accomplished by introducing nitrogen (N2) gas into the curing environment. However, this step is not necessary for the formation of a hard coating.

[0177] The cured composition must fill defect areas and any additional minor defects on the substrate surface to provide a smooth surface for the application of subsequent adhesive layer(s). It is not excluded that the composition of the present application may be applied in multiple coats that cure independently to achieve a desired layer thickness and cover surface defects.

[0178] For the sake of completeness, the present disclosure also relates to a method for placing multiple layers of an adhesive between substrate(s) to be bonded. The method comprises, as one of the constituent steps, applying the 2-part (2K) water-based polyurethane composition defined above as a primer to the surface of at least one substrate. More specifically, a method for manufacturing a multilayer adhesive typically comprises: i) providing a metallic substrate; ii) applying a first layer of the 2-part (2K) water-based polyurethane composition defined above onto the metallic substrate; iii) curing the first layer at least partially; iv) applying a second layer of a second curable adhesive composition onto the first layer that has been cured at least partially; and v) curing the second layer at least partially. In a repetitive process, steps ii) through v) may be performed and repeated to place third, fourth, and additional layers onto the metallic substrate. There is no particular intention to limit the types of adhesive compositions that can be applied in step iv): both water-based and solvent-based adhesive compositions are expected.

[0179] As used herein, the term “at least partially cured” means that the curing of a curable composition has been initiated, for example, that the crosslinking of the components of the composition has begun. This term encompasses any amount of curing from the formation of a single crosslink to a state of full crosslinking upon the application of curing conditions. Clearly, the rate and mechanism of curing of a composition depend on various factors, including its components, the functional groups of the components, and the parameters of the curing conditions.

[0180] At least partial solidification of a given adhesive layer generally indicates curing or drying. However, both drying and curing may also occur in other ways, such as by changes in the viscosity of the adhesive layer, increased temperature of the adhesive layer, and / or changes in the opacity of the adhesive layer.

[0181] The above or each step iv) of the coating process described above may preferably be initiated only when at least the partially cured or partially dried preceding layer can substantially maintain its shape when exposed to ambient conditions. “Substantially maintaining its shape” means that at least 50%, and more typically at least 80% or 90%, of the volume of the partially cured or dried layer maintains its shape and does not flow or deform when exposed to ambient conditions for a period of 5 minutes. In such situations, gravity should therefore not substantially affect the shape of at least the partially cured or partially dried layer when exposed to ambient conditions.

[0182] For completeness, the shape of the layer that is at least partially dried or at least partially cured will affect whether the layer substantially maintains its shape. For example, if the layer is rectangular or has other simple shapes, the layer that is at least partially cured or dried may be more resistant to deformation at much lower curing levels or much lower degrees of drying than layers with more complex shapes.

[0183] In certain embodiments, the application of a subsequent adhesive layer (step iv) occurs while the nominal layer is still in a "green" state, before at least the partially cured layer reaches a final cured state. In such embodiments, the application of the layers may be considered "wet-on-wet" so that adjacent layers are at least physically bonded and may also be chemically bonded to each other. For example, components within each of the first and subsequent layers may be chemically cross-linked / cured across the application line, and this effect may be beneficial to the lifespan, durability, and appearance of the finished article. Importantly, the distinction between the partially cured and final cured states is whether the partially cured layer can undergo further curing or cross-linking. This does not actually exclude the presence of functional groups in the final cured state, but such groups may remain unreacted due to steric hindrance or other factors.

[0184] In the above iterative process, the thickness, width, shape, and continuity of each layer can be selected independently, so that the preceding and subsequent layers may be identical or different from each other in one or more of these points. For example, a given subsequent layer may come into contact only with a portion of the exposed surface of at least partially cured or dried preceding layer: depending on the desired shape of the adhesive layer, the subsequent layer may be optionally built on top of that layer.

[0185] B) Debonding solution

[0186] The disjunction solution of the present disclosure has a pH of 3 to 14 and comprises the following:

[0187] i) C 10 to C 26 Fatty acid; C 10 to C 26 fatty acid salts; and C 10 to C 26At least one compound selected from the group consisting of C1-C4 alkyl esters of fatty acids; and,

[0188] ii) Polar solvent.

[0189] i) Fatty acids and their esters

[0190] As mentioned above, the solution is essentially i) C 10 to C 26 Fatty acid; C 10 to C 26 fatty acid salts; and C 10 to C 26 It comprises at least one compound selected from the group consisting of C1-C4 alkyl esters of fatty acids. The solution preferably comprises i) 5 to 30 weight% of the at least one compound based on the weight of the solution. And exemplary solutions may comprise i) 5 to 25 weight% or 10 to 25 weight% of the at least one compound.

[0191] The constituent fatty acids of the solution, or, where applicable, the fatty acids from which the said or each ester is derived, may be saturated, monounsaturated, or polyunsaturated linear aliphatic acids, examples thereof include: decanoic acid (capric acid); dodecanoic acid (lauric acid); tetradecanoic acid (myristic acid); pentadecanic acid; hexadecanoic acid (palmitic acid); heptadecanic acid (margaric acid); octadecanic acid (stearic acid or isostearic acid); octadecenic acids (oleic acid, linoleic acid or linolenic acid); hydroxyoctadecenoic acid (ricinoleic acid); eicosanic acid (arachidic acid); and docosanic acid (behenic acid).

[0192] C in solution 14 -C 20 A preference for using monounsaturated fatty acids and / or their C1-C4 alkyl esters may be mentioned. Independently or additionally to the preferred choice of these fatty acids, a preference for using C1-C2 alkyl esters and, more specifically, methyl esters may also be mentioned.

[0193] In an important embodiment, part i) of the solution is C 16 -C 18 Monounsaturated fatty acids and C 16 -C 18 It comprises or consists of at least one compound selected from the group consisting of C1-C4 alkyl esters of monounsaturated fatty acids. Good results were obtained when part i) of the composition comprises or consists of at least one compound selected from the group consisting of oleic acid and C1-C4 alkyl esters of oleic acid. For example, the composition may comprise or consist of at least one compound selected from the group consisting of oleic acid and C1-C2 alkyl esters. The use of oleic acid and / or methyl oleate as or in part i) of the solution may be particularly beneficial.

[0194] It will be recognized that fatty acids are typically obtained by the hydrolysis of naturally occurring triglycerides such as coconut oil, rapeseed oil, palm oils, tallow, lard, and fish oil. Hydrolysis yields mixtures of fatty acids, which may be useful in the present deconjugated solution. However, if specific individual fatty acids are required as components of the solution—such as oleic acid—these acids can be obtained from the mixtures by appropriate separation steps, such as distillation, nanofiltration, membrane separation, and separation via ion exchange resins.

[0195] ii) Polar solvents

[0196] The deconjugation solution comprises a polar solvent. Exemplary compounds that may constitute the polar solvent, either independently or in combination, are not limited thereto: water; C1-C8 alkanols such as ethanol; benzyl alcohol; acetonitrile; N,N-di(C1-C4)alkylacylamides such as N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc); hexamethylphosphoramide; N-methylpyrrolidone; pyridine; ethylene glycol mono-(C1-C4)-alkyl ethers, propylene glycol mono-(C1-C4)alkyl ethers, and particularly mono-C of diols having 2 to 12 carbon atoms such as ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, and propylene glycol monobutyl ether. 1-4 alkyl ethers; di(C2-C3)alkylene glycol mono-(C1-C4)alkyl ethers such as diethylene glycol monomethyl ether, diethylene monobutyl ether, dipropylene glycol n-propyl ether, dipropylene glycol monopropyl ether, and dipropylene glycol monobutyl ether; polyalkylene glycol dialkyl ethers; monoesters such as (C1-C8)alkyl acetates, ethoxydiglycol acetate, ethyl lactate, benzyl benzoate, butylocyl benzoate, and ethylhexyl benzoate; dibasic esters such as dimethyl succinate, dimethyl glutarate, dimethyl maleate, dimethyl adipate, and dipropyl oxalate; ketones such as acetone, ethyl ketone, methyl ethyl ketone (2-butanone), and methyl isobutyl ketone; Includes ethers such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF) and 1,2-dimethoxyethane; 1,3-dioxolane; dimethyl sulfoxide (DMSO); and dichloromethane (DCM).

[0197] Good results were obtained when the polar solvent comprises or consists of at least one compound selected from the group consisting of: water; polyalkylene glycol dialkyl ethers, in particular diethylene glycol dimethyl ether (Diglaim) or dipropylene glycol dimethyl ether (DPGDME); and dibasic esters. For completeness, an exemplary commercial dibasic ester solvent is Imsol R, a mixture of dimethyl succinate, dimethyl glutarate, and dimethyl adipate available from Invista.

[0198] iii) pH control agent

[0199] As mentioned above, the deconjugation solution must have a pH of 3 to 14, preferably 3 to 7 or 3 to 6. The pH control agent represents an optional component of the deconjugation solution, and the pH of the deconjugation solution determines the amount of any pH control agent added. Broadly, the pH control agent is selected from acidic substances and basic substances. For certainty, the added pH control agent is separate from component i) of the solution.

[0200] Exemplary acidic substances that may be added alone or in combination are, but are not limited to: inorganic acids; R m Formula R, which is a C1-C6 alkyl or C3-C6 cycloalkyl group m Monocarboxylic acids of CO2H; n is 2 or 3 and R p Formula R where is a C1-C6 alkylene or C3-C6 alkylene p (CO2H) n It includes polycarboxylic acids; and α-hydroxycarboxylic acid(s).

[0201] Regarding inorganic acids, the use of nitric acid is not excluded but undesirable; on the contrary, the addition of at least one of phosphoric acid, phosphonic acid, sulfurous acid, sulfuric acid, hydrochloric acid and hydrobromide is considered suitable.

[0202] Non-limiting examples of monocarboxylic acids include: formic acid; acetic acid; propionic acid; butyric acid; valeric acid; hexanoic acid; cyclohexanecarboxylic acid; cyclopentanecarboxylic acid; and cyclobutanecarboxylic acid. Formic acid, acetic acid, and propionic acid are considered particularly suitable for use herein.

[0203] Exemplary α-hydroxycarboxylic acids are those represented by general formula (III):

[0204] R h CH(OH)COOH (III)

[0205] Here: R h is a hydrogen atom, a C1-C4 alkyl group, a C2-C6 alkenyl group, a C1-C6 alkoxy group, a C3-C6 cycloalkyl group, or a C6-C 10 It represents an aryl group.

[0206] Suitable α-hydroxycarboxylic acids include, but are not limited to: glycolic acid; lactic acid (2-hydroxypropanoic acid); 2-hydroxybutanoic acid; 2-hydroxypentanoic acid; 2-hydroxyhexanoic acid; glucuronic acid; citric acid; mandelic acid; galacturonic acid; ribbon acid (2,3,4,5-tetrahydroxypentanoic acid); gluconic acid ((2S,3S,4R,5S)-2,3,4,5,6-pentahydroxyhexanoic acid); tartronic acid; tartaric acid; and malic acid.

[0207] Exemplary basic compounds that may be added to a disjunction solution, either alone or in combination, include but are not limited to: amine bases; alkali metals; alkaline earth metals; alkali metal (C1-C4) alkoxides; alkaline earth metal (C1-C4) alkoxides; alkali metal carbonates; alkaline earth metal carbonates; alkali metal hydroxides; alkaline earth metal hydroxides; alkali metal hydrides; and alkaline earth metal hydrides.

[0208] The term "amine base" as used herein refers to: ammonia (NH3); primary amines (NH2R a ); secondary amines (NHRa R b ); and tertiary amines (NR a R b R c Includes a reference to ), where R a , R b and R c Each is independently selected from alkyl, hydroxyalkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl, alkalyl, aralkyl, and heteroaryl, or R a and R b They can form carbocyclic or heterocyclic rings together.

[0209] According to embodiments of the present disclosure, the pH control agent is: ammonia; the chemical formula (NH2R a Primary amines of ); chemical formula NHR a R b Secondary amines of; and chemical formula NR a R b R c It comprises at least one amine base selected from the group consisting of tertiary amines, wherein R a , R b and R c Each is independently a C1-C6 alkyl, C1-C6 hydroxyalkyl, C3-C6 cycloalkyl, or C6-C 18 Selected from aryls, or R a and R b Together, they form a carbocyclic or heterocyclic ring having 4 to 8 constituent atoms.

[0210] Exemplary amine bases useful herein include: methylamine; ethylamine; propylamine; n-butylamine; dimethylamine; diethylamine; triethylamine; cyclohexylamine; N,N-diethylethanolamine; diethanolamine; triethanolamine; aniline, p-chloroaniline; N,N-dimethylaniline; benzylamine; piperidine; piperazine, 1-methylpiperazine, 1,4-dimethylpiperazine, and imidazole.

[0211] The aqueous deconjugation solution may contain an aqueous buffer that serves to maintain the solution within a desired pH range in specific situations, the range of which will be determined by the operating pH of the deconjugation process. For example, the following aqueous buffers may be useful herein: an acetate buffer for maintaining a pH of 4 to 5.5; a phosphate buffer for maintaining a pH of 6 to 8; and a glycine-sodium hydroxide buffer for maintaining a pH of 9. With respect to an operating pH of 6 to 8, suitable phosphate buffers include, but are not limited to: sodium phosphate; potassium phosphate; orthophosphate (H3PO4); ammonium phosphate (NH4H2PO4); and dibasic ammonium phosphate ((NH4)2HPO4).

[0212] The amount of water-soluble buffer added to the aqueous deconjugation solution should be effective in maintaining the pH within the desired pH range. For example, the water-soluble buffer may be added to the slurry in an amount of 1 to 1000 ppm by weight or 1 to 500 ppm by weight based on the total weight of the aqueous slurry.

[0213] iv) Surfactants

[0214] The present deconjugation solutions may optionally comprise at least one surfactant selected from: anionic surfactants; cationic surfactants; zodiac surfactants; nonionic surfactants; and mixtures thereof. The solution may comprise, for example, 0.5 to 50 weight% or 0.5 to 40 weight% of surfactants as a whole, based on the total weight of the composition. For certainty, the at least one surfactant is distinct from component i) of the composition.

[0215] In the embodiments, the surfactant(s) included in the solution include, are essentially composed of, or are composed of nonionic surfactants. The said or each surfactant included in the composition may be nonionic in the embodiments. The nonionic surfactants used in the composition may be characterized by a number average molecular weight (Mn) of 2,000 to 20,000 daltons, e.g., 2,000 to 10,000 daltons, or 2,000 to 8,000 daltons. Exemplary nonionic surfactants include: polyethylene oxides such as PEG 300 or PEG 400; fatty alcohols; primary alcohols (C2-C4)alkoxylates; secondary alcohols (C2-C4)alkoxylates; alkylphenols (C2-C4)alkoxylates; alkylaminos (C2-C4)alkoxylates; It includes amine polyglycol condensates such as Triton® CF-32 available from Union Carbide; polyoxy(C2-C3)alkylene fatty acid esters; polysorbates; sodium lauryl sulfate; sorbitan monolaurate; sorbitan monooleate; sorbitan monopalmitate; sorbitan trioleate; and silicone surfactants such as silicone polyether copolymers. However, the use of nonionic silicone surfactants is not desirable.

[0216] Commercial examples of suitable nonionic surfactants are: Lutensol ON 70, an ethoxylated (7EO) isodecyl alcohol available from BASF; and ethoxylated (5EO) saturated iso-C available from BASF. 13 It contains the alcohol Lutensol TO 5C.

[0217] In an embodiment, the surfactant(s) included in the deconjugation solution include, are essentially composed of, or are composed of anionic surfactants. The said or each surfactant included in the solution may be anionic in the embodiment. The anionic surfactants used in the solution may be characterized by a number average molecular weight (Mn) of 200 to 5000 daltons, e.g., 200 to 2000 daltons. Additionally, the anionic surfactants may be linear, partially branched, branched, or a mixture thereof.

[0218] Anionic surfactants may exist in an acidic form, or alternatively, the acidic form may be partially or wholly neutralized to form surfactant salts. Typical agents for neutralization include: metal counterionic bases such as alkali metal hydroxides; ammonia; amines; or alkanolamines including, but not limited to, monoethanolamine, diethanolamine, triethanolamine, 2-amino-1-propanol, 1-aminopropanol, monoisopropanolamine, and 1-amino-3-propanol. It is noted that neutralization of amines or alkanolamines may be performed wholly or partially. For example, part of the anionic surfactant may be neutralized with metal counterionic bases, and part of the anionic surfactant may be neutralized with amines or alkanolamines.

[0219] Non-limiting examples of suitable anionic surfactants are: alkoxylated alkyl sulfates, in particular (C2-C3)alkoxylated (C 12 -C 30 )alkyl sulfate surfactants and, more specifically, their water-soluble salts; sulfated C8-C 20 Non-alkoxylated alkyl sulfates including fatty alcohols and 2-alkyl branched primary alkyl sulfates; alkyl benzene sulfonates, in particular (C8-C 18 )alkyl benzene sulfonates and, more specifically, linear (C8-C 18) Alkyl benzene sulfonates; methyl ester sulfonates; paraffin sulfonates; α-olefin sulfonates; internal olefin sulfonates; and alkali metal sulfosuccinate esters are included.

[0220] Exemplary alkali metal sulfosuccinate esters useful in the present disclosure include sodium sulfosuccinate esters of the following formula:

[0221] NaO3SCH(CO2R')CH2CO2R

[0222] Here: R is H, C6-C 18 Alkyl or (C2-C3)alkoxylated (C6-C 18 )alkyl and; and,

[0223] R' is C6-C 18 Alkyl or (C2-C3)alkoxylated (C6-C 18 It is an alkyl.

[0224] The compounds according to this chemical formula may be mono- or diesters, and the use of the latter is preferred.

[0225] Commercial examples of suitable nonionic surfactants include: Triton GR 5M (1,4-bis(2-ethylhexyl) sodium sulfosuccinate) available from Dow Chemical; and LIAL® and ISALCHEM® available from Sasol.

[0226] Additives and auxiliary ingredients

[0227] The solutions may further include additives common in the field. In particular, the solutions may include, alone or in combination: corrosion inhibitors such as dialkylthioureas, copper(II) sulfate, and copper sulfate; oxygen scavengers; stabilizers including UV stabilizers; wetting agents; defoaming agents; metal chelating agents; lubricants; and rheological aids for controlling the viscosity or thixotropic properties of the solutions, examples of which include thickeners, fillers, and diluents.

[0228] Any such additives are inevitably minor components of the solutions and should be used only in amounts that are not detrimental to the performance of the solution when used. Additionally, with respect to any additive or auxiliary material, it is desirable that the material have a flash point of at least 90°C, for example, at least 100°C.

[0229] The following commercial materials may be mentioned as additional exemplary corrosion inhibitors: the Rodine® series available from JMN Specialties, Inc. and Henkel Corporation; the Dodicor® series available from Clariant AG; and the Armohib® series available from Akzo Nobel Surfactants LLC.

[0230] Thickeners represent optional components of the solution and may constitute 0 to 5 weight percent or 0 to 2 weight percent based on the total weight of the emulsion. Exemplary thickeners include, but are not limited to: cellulose-based thickeners and their derivatives; natural gums such as guar gum, karaya gum, locust bean gum, carrageenan, tragacanth gum, and xanthan gum; starches; stearates; fatty alcohols; hydrophobically modified alkali-soluble emulsion polymers (HASE); hydrophobically modified urethane-ethoxylate resins (HEUR); and acrylic acid polymers and crosslinking polymers. Particularly the use of cellulose-based thickeners and their derivatives may be mentioned, examples of which are: carboxymethyl hydroxyethylcellulose; cellulose; hydroxybutyl methylcellulose; hydroxyethylcellulose; hydroxypropylcellulose; It includes hydroxypropyl methylcellulose; methylcellulose; microcrystalline cellulose; and sodium cellulose sulfate.

[0231] The presence of nonpolar cosolvents and nonpolar diluents in the disjunction solutions of the present disclosure is also not excluded if their viscosity can be usefully controlled. If the required polar solvent comprises or consists of water, any added nonpolar cosolvent(s) or diluent must be a compound that is immiscible with water. Such compounds may be selected from the group consisting of: alkanes (RH); cyclic alkanes; branched alkanes; aromatics (Ar-H); alkyl halides (RX); and mixtures thereof. Exemplary but non-limiting nonpolar, water-immiscible solvents that may be used alone or in combination include n-pentane, n-hexane, cyclohexane, n-heptane, isooctane, trimethylpentane, toluene, xylene, and benzene.

[0232] Preparation of detachment solutions

[0233] Deconjugation solutions are formulated by simple mixing of various components, typically under stirring at room temperature. If necessary, the solution may be prepared well prior to its application. However, in an interesting alternative embodiment, a concentrated deconjugation solution may first be obtained by mixing the components with only a portion of the solvent present in the applied deconjugation solution: the concentrated deconjugation solution may then be diluted with the remaining solvent immediately before being introduced into the deconjugation bath. Such concentrated deconjugation solutions are considered to be prepared and stored as single-package concentrates that can be converted by dilution with solvent alone, or as multi-part concentrates that must be combined and diluted to form a complete working solution according to the present disclosure. Any dilution may be performed simply by adding a solvent—e.g., deionized water and / or demineralized water—under mixing. Deconjugation solutions may be prepared equally in a rinse stream in which streams of one or more concentrates are injected into a continuous stream of solvent.

[0234] Without any specific intention to limit the amount of solvent included in the disjunction solutions, it is preferable that the solutions contain 15 to 75 weight%, preferably 20 to 70 weight%, and more preferably 20 to 60 weight% of solvent based on the weight of the solution. In an alternative but non-mutually exclusive characterization, the disjunction solution may be defined as having a viscosity of 0.005 to 1 Pa.s (50 cps to 1000 cps) when measured using a Brookfield viscometer at 25°C.

[0235] Debonding methods and applications

[0236] The present disclosure further provides a method for detaching a joined article as described above, the method comprising the following steps:

[0237] a) a step of providing a bonded article as defined above and comprising at least one layer of a first adhesive interposed between two substrate surfaces, wherein the bonded article further comprises at least one layer of a second adhesive interposed between the two substrate surfaces;

[0238] b) a step of treating the bonded article with a disbonding solution as defined above at a temperature of 20 to 90°C; and,

[0239] c) A step of separating at least one layer of the first adhesive from the interposed state between the two substrate surfaces.

[0240] According to process embodiments of the present disclosure, it is often recommended to remove foreign substances, such as oil, soil, and metal powder, from the provided bonded article by cleaning the relevant surfaces before step b) of the cited method. Such treatments are known in the art and may be performed in a single or multi-step manner consisting of the use of one or more of: an aqueous cleaning emulsion; a cleaning solvent such as carbon tetrachloride or trichloroethylene; and preferably a water rinse of deionized or deionized water. After the cleaning, degreasing, and / or pretreatment steps, a disbonding composition is applied to the substrate (step b)). The disbonding composition may be applied at ambient temperature, or the temperature of the composition may be raised to a temperature in the range of, for example, 30°C to 90°C, or for example, 30°C to 75°C before application.

[0241] It is commercially common practice to manufacture the operating bath described above and to apply the disbonding composition to the bonded article, without limitation, by immersion, flooding, air-spray, air-assisted spray, airless spray, high-volume low-pressure spray, and air-assisted airless spray. The minimum contact time between the bonded article and the composition is, most broadly, sufficient to weaken the adhesive bonds so that the components can be separated by a reasonable or operable force. The contact time may be as short as 0.1 hours or as long as 48 hours when the disbonding treatment is performed at lower temperatures: however, depending on the pH and concentration of the applied solution and the temperature of application, a contact time of 0.1 to 24 hours or 0.5 to 20 hours will be more typical.

[0242] The present disclosure does not exclude the application of supplementary disbonding compositions to articles bonded with the disclosed solutions before or after treatment of articles bonded with the disclosed solutions. Accordingly, the present disclosure anticipates iterative processes in which treating articles bonded with the described disbonding solutions constitutes at least one step. Any supplementary disbonding compositions may be applied by any suitable means known in the art, such as immersion, dipping, spraying, roll-coating, electrodeposition; painting; brushing; wiping; air-spraying; air-assisted spraying; airless spraying; high-volume low-pressure spraying; and air-assisted airless spraying.

[0243] The removal of substrates from the adhesive (step c)) may or may not require the use of external force. For example, if the adhesive has completely separated from the substrate or even dissolved within the detachment composition(s) after the application of the detachment composition(s), external force may not be required. However, if at least a portion of the adhesive is still in contact with the substrate(s), external force may be used to completely peel off or remove the adhesive. For example, external force applied by liquid washing or mechanical force is used to compensate for the bond strength remaining between the adhesive(s) and the substrate(s).

[0244] In an embodiment, the tensile shear strength of the bonded substrates after step b) is up to 20 MPa, e.g., up to 15 MPa, up to 10 MPa, or even up to 5 MPa when determined according to ASTM-D1002.

[0245] After step c), it is not excluded that the above or each removed substrate undergoes at least one cleaning step. Cleaning may be performed in a conventional manner, including but not limited to the use of: an aqueous cleaning emulsion; a cleaning solvent such as carbon tetrachloride or trichloroethylene; preferably a water rinse of deionized or deionized water; a rinse of a dilute basic aqueous solution; and a rinse of a dilute silicate solution. Additionally, at the conclusion of step c) or any subsequent cleaning step, the removed substrate may be dried using, for example, ambient air drying, circulating hot air, forced air drying, or infrared heating. During drying, the surface temperature of the substrate(s) must be controlled to prevent any unwanted physical, morphological, or chemical changes to the substrate.

[0246] Various features and embodiments of the present disclosure are described in the following examples, which are intended to be representative and not limiting.

[0247] Examples

[0248] In the following examples, the following commercial products are used:

[0249] Dipropylene Glycol DME: Stabilized dipropylene glycol dimethyl available from Dow Chemical

[0250] Methocell 311: Hydroxypropyl methylcellulose available from Dow Chemical

[0251] Imsol R: A mixture of dimethyl succinate, dimethyl glutarate, and dimethyl adipate available from Invista

[0252] Triton GR 5M: 1,4-bis(2-ethylhexyl) sodium sulfosuccinate available from Dow Chemical

[0253] Mergital MES 2: Methyl oleates available from BASF

[0254] Lutensol ON 70: Ethoxylated (7EO) isodecyl alcohol available from BASF

[0255] Lutensol TO 5C: Ethoxylated (5EO) saturated iso-C available from BASF 13 alcohol

[0256] Technomelt PA6910: A semicrystalline polyamide polymer available from Henkel Corporation.

[0257] Aquence FD151: An aqueous dispersion of anionic polyurethane available from Henkel Corporation.

[0258] R297 (Desmodur Ultra DN): A hexamethylene diisocyanate (HDI)-based hydrophilic aliphatic polyisocyanate available from Covestro.

[0259] Dispercoll U8755: Anionic high molecular weight polyurethane dispersion available from Covestro AG.

[0260] Teroson 5065: A 2-component, solvent-free, epoxy resin-based adhesive available from Henkel Corporation.

[0261] All other compounds listed in the examples can be obtained from Sigma Aldrich.

[0262] Debonding solution 1

[0263] The first deconjugation solution (DB1) was prepared according to Table 1 below. The given components were mixed in a speed mixer (1200 rpm; 1 min) to ensure the formation of a homogeneous mixture. The first deconjugation solution (DB1) had a pH of 3.7.

[0264] ingredient Weight percentage of the composition (weight%) Dipropylene glycol DME 20.00 Methocell 311 0.30 Benzyl alcohol 20.00 Imsol R 37.40 Triton GR 5M 1.00 Formic acid (99%, aqueous solution) 1.00 Mergital MES2 20.30

[0265] Debonding solution 2

[0266] The second deconjugation solution (DB2) was prepared according to Table 2 below. The given components were mixed in a speed mixer (1200 rpm; 1 min) to ensure the formation of a homogeneous mixture. The prepared second deconjugation solution (DB2) had a pH of 8.0.

[0267] ingredient Weight percentage of the composition (weight%) oleic acid 12.00 Triethanolamine 25.00 Lutensol ON 70 30.00 Lutensol TO 5C 8.00 water 25.00

[0268] Example 1

[0269] In this embodiment, the lap shear strength of the bonded articles was investigated after the bonding area of ​​the substrates was completely immersed in the first disbonding solution (DB1).

[0270] The lap shear test substrates were aluminum (Alu3003), and their surfaces were cleaned with an ethyl acetate wipe. The substrates were provided with a thickness of 0.1 inches and were cut into six 2.5 cm x 10 cm (1" x 4") samples for tensile testing. Tensile lap shear (TLS) tests were performed at room temperature based on the ASTM D3163-01 standard test method for determining the strength of adhesively bonded rigid plastic lap-shear joints under tensile loading. For each specified substrate, the bond overlap area was 2.5 cm x 2.5 cm (1" x 1"), and the bond thickness was 0.1 cm (40 mil).

[0271] Where applicable, a primer was applied to one substrate in the overlapping area and dried at 100°C for 30 minutes to yield a layer with a dry film thickness of 100 microns. An additional adhesive composition (Teroson 5065) was applied and cured to a dry film thickness of 1 mm in the overlapping area by applying a temperature of 60°C for 2 hours. The bonded structures having the configuration shown in Fig. 1 were stored at 25°C and 20% relative humidity for 24 hours prior to the initial tensile test.

[0272] For each bonded article, tensile lap shear strength was investigated at the initial, 1 hour, 5 hours, and 18 hours after complete immersion in a disbonding solution maintained at a temperature of 60°C. Where possible, three samples were tested for each contact-time data point, and both the average tensile lap shear strength and its standard deviation were determined: the standard deviation is recorded in parentheses in Table 3 below.

[0273] Test number Primer layer Debonding solution Dejoining pH of the solution Tensile lap shear strength (MPa) at contact time 0 hours 1 hour 5 hours 18 hours 1 doesn't exist DB1 3.7 20.7 (3.0) 13.9 (2.2) 8.0 (2.4) 2 Aquence FD151 / R297 DB1 3.7 6.6 (1.2) 6.6 (0.5) 3.0 < 1.0 3 Dispercoll U8755 DB1 3.7 5.8 (0.4) 5.6 (2.6) 0.3 (0.1)

[0274] Example 2

[0275] In this embodiment, the lap shear strength of the bonded articles was investigated after the bonding area of ​​the substrates was completely immersed in the second disbonding solution (DB2).

[0276] The lap shear test substrates were aluminum (Alu3003), and their surfaces were cleaned with an ethyl acetate wipe. The substrates were provided with a thickness of 0.1 inches and were cut into six 2.5 cm x 10 cm (1" x 4") samples for tensile testing. Tensile lap shear (TLS) tests were performed at room temperature based on the ASTM D3163-01 standard test method for determining the strength of adhesively bonded rigid plastic lap-shear joints under tensile loading. For each specified substrate, the bond overlap area was 2.5 cm x 2.5 cm (1" x 1"), and the bond thickness was 0.1 cm (40 mil).

[0277] Where applicable, a primer was applied to one substrate in the overlapping area and dried at 100°C for 30 minutes to yield a layer with a dry film thickness of 100 microns. An additional adhesive composition (Teroson 5065) was applied and cured to a dry film thickness of 1 mm in the overlapping area by applying a temperature of 60°C for 2 hours. The bonded structures having the configuration shown in Fig. 1 were stored at 25°C and 20% relative humidity for 24 hours prior to the initial tensile test.

[0278] For each bonded substrate, tensile lap shear strength was investigated at the initial, 1 hour, 5 hours, and 18 hours after complete immersion in a disbonding solution maintained at a temperature of 60°C. Where possible, three samples were tested for each contact-time data point, and both the average tensile lap shear strength and its standard deviation were determined: the standard deviation is recorded in parentheses in Table 4 below.

[0279] Test number Primer layer Debonding solution pH of the deconjugation solution Tensile lap shear strength (MPa) at contact time 0 hours 1 hour 5 hours 18 hours 1 doesn't exist DB2 8 20.7 (3.0) 13.5 (2.0) 5.3 2 Aquence FD151 / R297 DB2 8 6.6 (1.2) 7.1 (0.3) 1.9 < 1.0 3 Dispercoll U8755 DB2 8 6.7 (1.0) 3.4 (2.0) 4 Dispercoll U8755 DB2 1 13 8.8 (5.1) 3.5 (2.7)

[0280] 1 The pH of this deconjugation solution was achieved by adding sodium hydroxide to the solution in Table 2 above.

[0281] Considering the foregoing description and embodiments, it will be apparent to those skilled in the art that equivalent variations thereof may be made without departing from the scope of the claims.

Claims

Claim 1 A bonded article comprising at least one layer of a first adhesive interposed between two substrate surfaces, wherein the bonded article further comprises at least one layer of a second adhesive interposed between the two substrate surfaces, wherein: the layer or each layer of the first adhesive has a dry film thickness of 10 to 500 μm; the first adhesive is a polyurethane adhesive selected from water-based polyurethane dispersion adhesives and polyurethane hot melt adhesives; the first adhesive is different from the second adhesive; and the second adhesive has a higher intralayer cohesive strength than the first adhesive when determined according to ASTM F88-94. Claim 2 A bonded article according to claim 1, comprising: a first substrate having an internal surface; and a second substrate having an internal surface, wherein layers of the first adhesive and the second adhesive are interposed between the internal surfaces of the first and second substrates. Claim 3 A bonded article according to claim 1 or 2, wherein at least one of the first and second substrates is metallic. Claim 4 A bonded article according to any one of claims 1 to 3, wherein the layer or each layer of the first adhesive has a dry film thickness of 30 to 300 μm. Claim 5 A bonded article according to any one of claims 1 to 4, wherein at least one layer of the first adhesive is in direct contact with the surface of the substrate. Claim 6 In any one of claims 1 to 5, the first adhesive comprises: p) a first part comprising the following: (pi) at least one anionic polyurethane polymer having pendant hydroxyl groups; and, q) a second part comprising at least one polyisocyanate compound having pendant -NCO groups, obtained by curing a 2-part (2K) aqueous composition, wherein the molar ratio of active hydrogen atoms to -NCO groups in the composition is 5:1 to 1:5, the bonded article. Claim 7 A bonded article comprising, wherein part p) of the 2-part (2K) aqueous composition comprises: a hydroxyl functional value of 2 to 4; a hydroxyl value of 0.5 to 10 mg KOH / g, preferably 0.5 to 4 mg KOH / g; and a weight average molecular weight (Mw) of 50 to 200 kDa, preferably 50 to 150 kDa, more preferably 50 to 125 kDa. Claim 8 In claim 6 or 7, part q) of the 2-part (2K) aqueous composition comprises a linear aliphatic polyisocyanate, a bonded article. Claim 9 In the detachment of an adhesively bonded article as defined in any one of paragraphs 1 to 8, C 10 to C 26 Fatty acids; C 10 to C 26 Salts of fatty acids; and C 10 to C 26 Use of a solution in a polar solvent of at least one compound selected from the group consisting of C1-C4 alkyl esters of fatty acids, wherein the deconjugation solution has a pH of 3 to 14. Claim 10 In claim 9, the above-mentioned disjunction solution is based on the weight of the solution: C 10 to C 26 Fatty acids; C 10 to C 26 Salts of fatty acids; and C 10 to C 26 Use comprising 5 to 30 weight%, preferably 5 to 25 weight%, of at least one compound selected from the group consisting of C1-C4 alkyl esters of fatty acids. Claim 11 In claim 9 or 10, the at least one compound of the debonding solution is C 16 -C 18 Monounsaturated fatty acids; C 16 -C 18 Salts of monounsaturated fatty acids; and C 16 -C 18 Selected from the group consisting of C1-C4 alkyl esters of monounsaturated fatty acids. Claim 12 In claim 9 or 10, the at least one compound of the deconjugation solution is selected from the group consisting of oleic acid; salts of oleic acid; and C1-C2 alkyl esters of oleic acid. Claim 13 In any one of claims 9 to 12, the polar solvent of the deconjugation solution comprises or consists of at least one compound selected from the group consisting of water; polyalkylene glycol dialkyl ethers; and dibasic esters. Claim 14 In any one of claims 9 to 13, the deconjugation solution further comprises, based on the weight of the solution: 0.5 to 50 weight%, preferably 0.5 to 40 weight%, at least one surfactant selected from the group consisting of nonionic surfactants and anionic surfactants. Claim 15 A method for detaching a bonded article, comprising: a) providing a bonded article as defined in any one of claims 1 to 8, wherein the bonded article comprises at least one layer of a first adhesive interposed between two substrate surfaces, and the bonded article further comprises at least one layer of a second adhesive interposed between the two substrate surfaces, wherein: The layer or each layer of the first adhesive has a dry film thickness of 10 to 500 μm; and, Step of providing the bonded article, wherein the first adhesive is a polyurethane adhesive selected from water-based polyurethane dispersion adhesives and polyurethane hot melt adhesives; b) at a temperature of 20 to 90°C, C 10 to C 26 Fatty acids; C 10 to C 26 Salts of fatty acids; and C 10 to C 26 A method for debonding a bonded article, comprising: a step of treating the bonded article with a solution in a polar solvent of at least one compound selected from the group consisting of C1-C4 alkyl esters of fatty acids, wherein the solution has a pH of 3 to 14; and, c) a step of separating at least one layer of the first adhesive from an interposed state between the two substrate surfaces. Claim 16 A method for debonding a bonded article according to claim 15, wherein the processing step comprises immersing the bonded article in the solution. Claim 17 A method for detaching a bonded article, wherein, in claim 15 or 16, the processing step is performed at a temperature of 30 to 75°C. Claim 18 A method for detaching a bonded article, wherein, in any one of claims 15 to 17, the processing step is characterized by a contact time of 0.1 to 24 hours, preferably 0.5 to 20 hours.

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