Thermally debondable primer composition

Abstract

The present invention relates to a thermally debondable primer composition, the thermally debondable primer composition comprising: a polyether urethane methacrylate resin; two or more (meth) acrylate monomers; a thermally expandable thermoplastic microsphere; and one or more photoinitiators.

Description

Technical Field

[0001] This invention relates to a UV-curable and heat-detachable primer composition. Background Technology

[0002] Adhesive bonding and polymer coatings are commonly used in the assembly and finishing of finished products. They are used in place of mechanical fasteners such as screws, bolts, and rivets to provide adhesion with reduced machining costs and greater applicability during manufacturing. Adhesive bonding distributes stress evenly, reduces the likelihood of fatigue, and seals joints against corrosive substances.

[0003] While adhesive bonding offers many advantages over mechanical fasteners, in practical applications, it can be difficult to disassemble adhesively bonded items when required. Mechanical methods (such as sandblasting or wire brushing) are typically ruled out for adhesive removal, partly because the adhesive is embedded between the substrates and is therefore difficult to access or grind without damaging the substrate surfaces. Disassembly by applying chemicals and / or high temperatures may be effective, but it is time-consuming and complex; furthermore, the required corrosive chemicals and / or harsh conditions can damage the separated substrates, rendering them unsuitable for subsequent applications.

[0004] As an example, it is obviously desirable to remove, replace, and / or recycle automotive industry components (such as electric vehicle battery cells and casques) that have been attached to the equipment using adhesives. However, such adhesives are often very strong, as they are designed to remain bonded during drop or impact events and across a wide range of operating temperatures and other environmental conditions. If not handled carefully, adhesive-bonded equipment components can be damaged or destroyed when removed by mechanical methods or by applying chemicals.

[0005] Some authors have attempted to develop debonded adhesive compositions in which applied heat is used to break the bond at the adhesive-substrate interface. The problem with thermal debonding is that, if not handled carefully, the high temperature can damage the substrate. Furthermore, the use of thermally expandable microspheres may negatively impact the mechanical and adhesive strength properties of the adhesive.

[0006] Noting these issues, some authors have also attempted to develop debonded adhesive compositions in which an electric current acts through the cured composition to break the bond at the interface between the adhesive and the substrate.

[0007] Therefore, there remains a need in the art to provide means for effectively debonding bonded substrates while maintaining the optimal adhesive and mechanical properties of the adhesive. Summary of the Invention

[0008] This invention relates to a heat-detachable primer composition comprising: a) a polyether urethane methacrylate resin; b) two or more (meth)acrylate monomers; c) heat-expandable thermoplastic microspheres; and d) one or more photoinitiators.

[0009] The present invention also relates to a cured, heat-detachable primer composition according to the invention, wherein the heat-detachable primer composition is cured by photocuring.

[0010] The present invention also relates to the use of the heat-detachable primer composition or cured product according to the present invention in bonded structures.

[0011] The present invention includes an adhesive structure comprising: a first substrate; a second substrate; a heat-detachable primer composition layer or cured product layer according to the present invention; and an adhesive layer, wherein the heat-detachable primer is disposed on the surface of the first substrate and / or the surface of the second substrate, and wherein the adhesive layer is placed on the heat-detachable primer layer.

[0012] A method for debonding an adhesive structure according to the invention, the method comprising the steps of: i) applying heat; and ii) debonding the surfaces. Attached Figure Description

[0013] Figure 1 The tensile lap shear strength of TEROSON EP 5065 on KTL steel specimens was demonstrated in the temperature range of -40°C to 130°C.

[0014] Figure 2 The debonding efficiency of composition 1 was demonstrated by the tensile lap shear strength of TEROSON EP 5065 on an electro-coated steel specimen.

[0015] Figure 3 An example of a test setup for monitoring battery box temperature during the debonding process is provided.

[0016] Figure 4 An example is given of the temperature change of the battery cell during the debonding stage using a structural adhesive (TEROSON EP 5065).

[0017] Figure 5 The example illustrates the temperature change of the battery cell during the debinding phase using TCA. Detailed Implementation

[0018] The invention is described in more detail in the following paragraphs. Unless expressly stated to the contrary, each aspect thus described may be combined with any one or more other aspects. In particular, any feature indicated as preferred or advantageous may be combined with any one or more other features indicated as preferred or advantageous.

[0019] In the context of this invention, unless the context otherwise requires, the terminology used shall be interpreted in accordance with the following definitions.

[0020] Unless the context clearly specifies otherwise, the singular forms “a” and “the” used herein include both the singular and plural references.

[0021] The terms “comprising” and “containing” as used herein are synonymous with “including” or “containing”, are inclusive or open-ended, and do not exclude additional unlisted members, elements, or method steps.

[0022] As used in this article, the term " Composed of... Exclude any unspecified elements, components, members, or method steps.

[0023] Words " Preferred " expect "and" in particular "The term is generally used herein to refer to embodiments of the present disclosure that may provide particular benefits in certain circumstances. However, the description of one or more preferred, preferred, desired or particular embodiments does not imply that other embodiments are unavailable, and is not intended to exclude those other embodiments from the scope of the present disclosure."

[0024] As used throughout this application, the term " Possibly / May / Possibly "It is used in a permissible sense (i.e., it means possible), not in a mandatory sense."

[0025] As used in this article, the term " Detachable This means that after the primer has cured, the adhesive strength can decrease by at least 50% when heat is applied at 60 to 200°C for 2 to 60 minutes. The cured primer and adhesive are applied between two substrates, which are bonded together by the adhesive. The adhesive strength is measured by a tensile lap shear (TLS) test at room temperature based on ISO 4587. The bonded overlap area is 25 mm × 10 mm, and the bond thickness is approximately 150 µm.

[0026] As used in this article, the term " monomer "A substance is a substance that can undergo polymerization to provide structural units for the chemical structure of a polymer." The term "a substance" as used in this article... Monofunctional"" refers to having an aggregateable part. The term "" as used in this article polysaccharidosis "" refers to having more than one aggregateable part.

[0027] As used in this article, " (Meth)acryloyl "for reference" Acryloyl "and / or " Methacryloyl The abbreviation of "". Therefore, the term " (Methacrylamide) "A collective term for acrylamide and methacrylamide."

[0028] The list of numerical endpoints includes all numbers and fractions that fall into their respective ranges, as well as the listed endpoints.

[0029] Unless otherwise stated, all percentages, portions, proportions, etc. mentioned herein are based on weight.

[0030] When a quantity, concentration, or other value / parameter is expressed in the form of a range, a preferred range, or a preferred upper limit and a preferred lower limit, it should be understood that any range obtained by combining any upper limit or preferred value with any lower limit or preferred value is also specifically disclosed, regardless of whether the obtained range is explicitly mentioned in the context.

[0031] All references cited in this specification are incorporated herein by way of citation.

[0032] Unless otherwise defined, all terms used in this disclosure (including technical and scientific terms) have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains. Further guidance includes terminology definitions to better understand the teachings of this invention.

[0033] The present invention relates to a heat-detachable primer composition comprising: a) a polyether urethane methacrylate resin; b) two or more (meth)acrylate monomers; c) heat-expandable thermoplastic microspheres; and d) one or more photoinitiators.

[0034] The applicant has discovered that the heat-detachable primer composition according to the invention provides excellent detack properties and can be easily peeled off from the substrate, particularly for electrocoated steel.

[0035] The heat-detachable primer composition according to the present invention comprises polyether urethane methacrylate resin.

[0036] Preferably, the polyether urethane methacrylate resin is derived from polyether polyol, hydrogenated bisphenol A, and toluene 2,4-diisocyanate having methacrylate functional groups.

[0037] The polyether urethane methacrylate resin may be present in the composition in an amount of 30 to 55% by weight, preferably 35 to 50% by weight, and more preferably 37 to 47% by weight, of the total weight of the heat-release primer composition according to the invention.

[0038] The above-defined and preferred ranges are ideal for film formation. Amounts below 30% may result in poor film formation, while amounts that are too high (greater than 55%) may result in a highly viscous composition that may be difficult to process.

[0039] The compositions according to the present invention comprise two or more (meth)acrylate monomers.

[0040] The (meth)acrylate monomers suitable for use as the (meth)acrylate component in this invention can be selected from a variety of materials, such as those represented by the following. H2C=CGCO2R 1 , in G can be hydrogen, halogen, or an alkyl group having 1 to 4 carbon atoms, and R 1 It may be selected from alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkylaryl, alkylaryl or aryl groups having 1 to 16 carbon atoms, any one of which may be optionally substituted or interrupted by silane, silicon, oxygen, halogen, carbonyl, hydroxyl, ester, carboxylic acid, urea, urethane, carbonate, amine, amide, sulfur, sulfonate, sulfone or the like.

[0041] Preferably, two or more (meth)acrylate monomers are selected from butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecanyl (meth)acrylate, octadecyl (meth)acrylate, and so on. (Meth)nonadecanyl acrylate, (Meth)eicosyl acrylate, (Meth)isobutyl acrylate, (Meth)isoamyl acrylate, (Meth)isohexyl acrylate, (Meth)isoheptyl acrylate, (Meth)isooctyl acrylate, (Meth)2-ethylhexyl acrylate, (Meth)sec-butyl acrylate, (Meth)1-methylbutyl acrylate, (Meth)1-ethylpropyl acrylate, (Meth)tetrahydrofurfuryl acrylate, (Meth)isobornyl acrylate, alkoxylated (Meth)tetrahydrofurfuryl acrylate, cyclic trimethylolpropane methyl acetal acrylate, (Meth) 2-Phenoxyethyl acrylate, alkoxylated nonylphenol acrylate, alkoxylated phenol acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, alkoxylated lauryl acrylate, stearyl acrylate, isodecyl acrylate, caprolactone methacrylate, methoxy polyethylene glycol (350) monoacrylate and methoxy polyethylene glycol (550) monoacrylate, polyethylene glycol di(meth)acrylate, tetrahydrofuran acrylate, hydroxypropyl acrylate, hydroxyethyl acrylate, (Meth)acrylic acid, itaconic acid, hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, di(pentamethylene glycol) di(meth)acrylate, tetraethylenediethylene glycol di(meth)acrylate, diglycerol tetra(meth)acrylate, tetramethylene di(meth)acrylate, ethylene di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethoxylated bisphenol-A (meth)acrylate, and mixtures thereof; preferably selected from isobornyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylic acid, itaconic acid, and mixtures thereof; and more preferably selected from isobornyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylic acid, and mixtures thereof.

[0042] In a highly preferred embodiment, two or more (meth)acrylate monomers are isobornyl acrylate, acrylic acid, and hydroxyethyl methacrylate.

[0043] Preferred monomers provide good adhesion to non-metallic and / or metallic substrates, and thus provide optimized metal-to-polymer adhesion.

[0044] Commercially available (meth)acrylate monomers suitable for use in this invention include, but are not limited to, isobornyl acrylate from OSAKA and hydroxyethyl methacrylate from GEO.

[0045] Two or more (meth)acrylate monomers may be present in the composition in an amount of 20 to 50% by weight, preferably 25 to 45% by weight, preferably 27 to 41% by weight, and more preferably 30 to 38% by weight, of the total weight of the heat-release primer composition according to the invention.

[0046] These preferred amounts are preferred because too high an amount may result in a composition that is too hard, while too low an amount may result in a poor curing rate.

[0047] The compositions according to the present invention comprise thermally expandable thermoplastic microspheres.

[0048] Suitable thermally expandable thermoplastic microspheres have a core-shell structure, wherein the shell is formed of a cross-linked polymer and the core is composed of a foaming agent.

[0049] Suitable crosslinked polymers can be prepared by (co)polymerization of any suitable monomer or comonomer. Suitable monomers that can be used to prepare polymers include nonionic olefinically unsaturated monomers.

[0050] Suitable nonionic olefinic unsaturated monomers for use in this invention may be selected from styrene, vinyltoluene, ethylene, butadiene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, acrylamide, methacrylamide, C1-C20 alkyl esters or C2-C20 alkenyl esters of acrylic acid or methacrylic acid, methacrylates, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, benzyl acrylate, benzyl methacrylate, lauryl acrylate, lauryl methacrylate, oleyl acrylate, oleyl methacrylate, palmitate acrylate, palmitate methacrylate, octadecyl acrylate, octadecyl methacrylate, hydroxyl-containing monomers (especially C1-C10 hydroxyalkyl esters of (meth)acrylate, such as hydroxyethyl methacrylate, hydroxypropyl methacrylate), glycidyl methacrylate, preferably methyl methacrylate and mixtures thereof.

[0051] Suitable polymers can also be copolymers prepared by copolymerization of two or more monomers listed above. Preferred monomer combinations include acrylonitrile / (meth)acrylate, styrene / (meth)acrylate, acrylamide / (meth)acrylate, and acrylonitrile / (meth)acrylate hydroxyethyl ester. A more preferred combination is acrylonitrile / methyl methacrylate.

[0052] Suitable crosslinking agents for crosslinking polymers in this invention are compounds having two or more olefinically unsaturated groups, such as diacrylates or dimethacrylates of at least a dihydroxy saturated alcohol, for example, ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,2-propanediol diacrylate, 1,2-propanediol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, hexanediol diacrylate, hexanediol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, 3-methylpentyl glycol diacrylate, and 3-methylpentyl glycol dimethacrylate. Another class of crosslinking agents includes diacrylates or dimethacrylates of polyethylene glycol or polypropylene glycol with a molecular weight of 200 to 9000 in each case. The polyethylene glycol and / or polypropylene glycol used to prepare the diacrylates or dimethacrylates preferably each have a molecular weight of 400 to 2000. Not only homopolymers of ethylene oxide and / or propylene oxide can be used, but also block copolymers of ethylene oxide and propylene oxide, or random copolymers of ethylene oxide and propylene oxide (which contain a random distribution of ethylene oxide and propylene oxide units). Similarly, oligomers of ethylene oxide and / or propylene oxide can be used to prepare crosslinking agents, examples of which are diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, and / or tetraethylene glycol dimethacrylate.

[0053] The amount of crosslinking agent used is preferably 0.1% to 30%, depending on the monomer to be polymerized at any stage.

[0054] The core is preferably composed of a physical blowing agent. Suitable physical blowing agents include alkanes and / or cycloalkanes having at least 4 carbon atoms, dialkyl ethers, esters, ketones, acetals, fluoroalkanes having 1 to 8 carbon atoms, and tetraalkylsilanes (especially tetramethylsilane) having 1 to 3 carbon atoms in the alkyl chain.

[0055] Examples of suitable blowing agents that may be used according to the invention include propane, n-butane, isobutane and cyclobutane, n-pentane, isopentane and cyclopentane, cyclohexane, dimethyl ether, methyl ethyl ether, methyl butyl ether, methyl formate and acetone, and fluoroalkanes that degrade in the troposphere and are therefore ozone-free, such as trifluoromethane, difluoromethane, 1,1,1,3,3-pentafluorobutane, 1,1,1,3,3-pentafluoropropane, 1,1,1,2-tetrafluoroethane, difluoroethane and 1,1,1,2,3,3,3-heptafluoropropane, and perfluoroalkanes (such as CsFs, C4Fs). 10 C5F 12 CeFi4 and C7F 16 The foaming agents can be used alone or in any combination of each other.

[0056] In addition, hydrofluoroolefins (such as 1,3,3,3-tetrafluoropropylene) or hydrochlorofluoroolefins (such as 1-chloro-3,3,3-trifluoropropylene) can be used as blowing agents.

[0057] In a preferred embodiment, the physical blowing agent is a hydrocarbon, preferably selected from alkanes and / or cycloalkanes having at least four carbon atoms. In particular, pentane is used, preferably isopentane and cyclopentane. Cyclopentane is preferred when rigid foam is used as an insulation material in cooling equipment. The hydrocarbon can be used in the form of a mixture with water.

[0058] Thermally expandable microspheres can be prepared by seed swelling of cross-linked polymers and encapsulation with foaming agents.

[0059] The thermally expandable thermoplastic microspheres have a particle size of 5 to 100 μm, preferably 8 to 75 μm, preferably 9 to 50 μm, more preferably 10 to 30 μm, more preferably 12 to 20 μm, and even more preferably 13 to 19 μm, wherein the particle size is measured by laser diffraction (low angle laser light scattering LALLS).

[0060] The particle size range defined above refers to the size before expansion.

[0061] The thermoplastic microspheres that can expand thermally expand when exposed to heat, preferably when exposed to heat of 60°C to 200°C, more preferably 80°C to 160°C, and more preferably 80°C to 120°C.

[0062] The heat source can be, for example, a thermal source, an ultrasonic probe, or an electromagnetic source.

[0063] Commercially available thermally expandable thermoplastic microspheres suitable for use in this invention include, but are not limited to, Expansionl 031DU40 from Nouryon.

[0064] Based on the total weight of the heat-detachable primer composition according to the invention, the heat-expandable thermoplastic microspheres are present in the composition in an amount of 5 to 30% by weight, preferably 10 to 27% by weight, preferably 12 to 25% by weight, and more preferably 14 to 22% by weight.

[0065] The above-defined and preferred ranges are ideal for breaking down the adhesive layer while maintaining a low solids content in the composition. Amounts less than 5% may not result in complete adhesive failure, while excessive amounts may increase the solids content too much without providing any additional technical benefits.

[0066] The compositions according to the present invention comprise one or more photoinitiators.

[0067] Photoinitiators suitable for use in this invention are active in the UV / visible light range (about 250 to 850 nm) or a segment thereof. More preferably, the photoinitiators used in this invention are active in the UV / visible light range (about 250 to 850 nm), and preferably in the range of 300 to 450 nm, so that the composition can be cured by exposure to low-intensity UV.

[0068] Preferably, one or more photoinitiators are selected from 1-hydroxycyclohexylphenyl ketone, ethyl phenyl benzoyl phosphinate, 2-hydroxy-2-methyl-1-phenyl-prop-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl-ketone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylprop-1-one, 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinylphenyl)-1-butanone, a combination of 1-hydroxycyclohexylphenyl ketone and benzophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1- Combinations of phenyl-1-propane, 2,4,6-trimethylbenzoyl diphenylphosphine oxide and 2-hydroxy-2-methyl-1-phenyl-prop-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-prop-1-one, 50 wt% diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and 50 wt% 2-hydroxy-2-methyl-1-phenyl-1-one, bis(2,6-dimethoxybenzoyl-2,4,4-trimethylpentyl)phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-prop-1-one, bis(η <5> -2,4-cyclopentadien-1-yl)-bis[2,6-difluoro-3-(1H-pyrrolo-1-yl)phenyl]titanium, 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone, dl-camphorquinone, and mixtures thereof; preferably selected from ethylphenylbenzoylphosphinate, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-prop-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl-ketone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and mixtures thereof; and more preferably selected from ethylphenylbenzoylphosphinate, 1-hydroxycyclohexylphenyl ketone, and mixtures thereof.

[0069] These photoinitiators are preferred because they offer a good combination of surface curing and deep curing, and in addition, they provide good UV and visible LED curing.

[0070] Commercially available photoinitiators suitable for use in this invention include, but are not limited to, Omnirad 184 and Omnirad TPO-L from IGM Resins.

[0071] Based on the total weight of the heat-detachable primer composition according to the invention, one or more photoinitiators are present in the composition in an amount of 0.5 to 10% by weight, preferably 1.25 to 8% by weight, more preferably 1.5 to 5% by weight.

[0072] These amounts are preferred because amounts less than 0.5% may result in poor curing, while amounts that are too high (greater than 10%) may result in loss of mechanical properties and premature polymerization, short chain lengths, and termination before crosslinking.

[0073] The compositions according to the invention may further contain an adhesion promoter.

[0074] Adhesion accelerators function at the interface between organic adhesive materials and organic / inorganic substrates to improve the adhesion between the two materials. These materials often differ in several ways, making it difficult to form a strong adhesive bond between them, such as differences in compatibility, chemical reactivity, surface properties, and coefficients of thermal expansion. Adhesion accelerators function to bond these dissimilar materials into a strong cohesive adhesive structure through chemical and physical means. Adhesion accelerators can impart resistance to environmental and other destructive forces (such as heat and moisture) that often act on the bonded sites to weaken the bond strength.

[0075] Preferably, the adhesion promoter is selected from glycidoxypropyltrimethoxysilane, acrylic acid, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxyethyltrimethoxysilane, γ-glycidoxymethyltrimethoxysilane, γ-glycidoxymethyltriethoxysilane, γ-glycidoxyethyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, and 8-glycidoxy-n-octyltrimethoxysilane, and mixtures thereof; preferably, the bifunctional adhesion promoter is selected from glycidoxypropyltrimethoxysilane, acrylic acid, and mixtures thereof.

[0076] Commercially available adhesion promoters suitable for use in this invention include, but are not limited to, icy acrylic acid from BASF and Silquest A 187 from Momentive.

[0077] The adhesion promoter may be present in the composition in an amount of 0.5 to 8% by weight, preferably 0.75 to 5% by weight, and more preferably 0.75 to 3% by weight, of the total weight of the heat-detachable primer composition according to the invention.

[0078] The ranges selected above provide ideal adhesion promotion; however, if the amount of adhesion promoter exceeds 8%, it may have an adverse effect on curing performance.

[0079] The heat-release primer composition according to the invention may further comprise additives and auxiliaries that can impart improved properties to such composition. For example, the additives and auxiliaries may impart one or more of the following: improved elastic properties; improved elastic recovery; longer allowable processing time; faster curing time; film-forming properties; and lower residual tack.

[0080] The auxiliaries and additives used in this invention may be selected from: fillers, extenders, dyes, adhesives, crosslinking agents, stabilizers, solvents, rheology modifiers, dispersants, fungicides, bactericides, algaecides, and mixtures thereof.

[0081] Suitable fillers for use in this invention are, for example, titanium oxide.

[0082] Incremental agents suitable for use in this invention are used to improve adhesion and strengthen the film. Non-limiting examples of incremental agents suitable for use in this invention are aluminum silicate, silicon dioxide, barium sulfate, aluminum manganese silicate, aluminum magnesium sodium silicate, calcium carbonate, calcium sulfate, diatomaceous earth, carbon black, mica, and mixtures thereof.

[0083] The solvents suitable for use in this invention are primarily used to improve the liquid properties and drying characteristics of the primer composition. Suitable solvents for use in this invention are, for example, isopropanol.

[0084] Suitable crosslinking agents can be used to modify the properties of the primer composition, for example, to improve environmental resistance. Suitable crosslinking agents for use in this invention are, for example, isocyanates, aziridines, and cyanurates.

[0085] Suitable dispersants can be used to separate and stabilize particles. Suitable dispersants for use in this invention include, for example, hydrophobic acrylic copolymer pigment dispersants, such as Orotan 681 from Dow.

[0086] Such auxiliaries and additives may be used as needed in such combinations and proportions, provided that they do not adversely affect the properties and essential characteristics of the composition. While there may be exceptions in some cases, these auxiliaries and additives should not total more than 30% of the total composition, and preferably should not exceed 10%.

[0087] The heat-release adhesive composition according to the invention can be prepared by adding all components to a container and mixing (e.g., by mixing with a high-speed mixer).

[0088] The heat-release primer composition according to the invention can be applied to the surface of a substrate by any available means to form a film. The primer composition can be applied using a brush coating technique or by using a doctor blade coater with a guide. The guide of the doctor blade coater can be 50 micrometers, 100 micrometers, or even greater than 200 micrometers; preferably, the primer composition is applied using a doctor blade coater with a 100-micrometer guide.

[0089] The thickness of the heat-detachable primer composition layer on the substrate can be from 20 μm to 300 μm, preferably from 30 μm to 175 μm, and more preferably from 45 μm to 150 μm.

[0090] The thicknesses listed above are for the wet layer, while the thickness of the dry layer is approximately half that of the wet layer.

[0091] These thicknesses are ideal because they enable the deposition of microparticles and, additionally, facilitate the peeling of the undercoat layer from the substrate during the expansion of the thermally expandable thermoplastic microspheres.

[0092] This invention relates to a cured, heat-release adhesive composition according to the invention.

[0093] The heat-detachable primer composition according to the present invention can be used with a 365 nm lamp at 20 to 500 mW / cm. 2 The light is applied at a certain intensity to cure the material, wherein the curing time can be adjusted appropriately according to the intensity.

[0094] In a preferred embodiment, the heat-detachable primer composition according to the invention is tested with a 365 nm lamp at 320 mW / cm². 2 It is cured by applying UV light for 150 seconds at a certain intensity.

[0095] The heat-release primer composition or cured product according to the present invention can be used in bonded structures.

[0096] Examples of bonded structures are automotive parts (such as batteries, housings, and internal components).

[0097] The present invention relates to an adhesive structure comprising: a first substrate; a second substrate; a heat-detachable primer composition layer or cured product layer according to the present invention; and an adhesive layer, wherein the heat-detachable primer is disposed on the surface of the first substrate and / or the surface of the second substrate, and wherein the adhesive layer is placed on the heat-detachable primer layer.

[0098] The first and second substrates can be the same or different, and are not limited to any particular substrate material. However, a suitable substrate should have temperature stability below the debonding temperature and a melting point above 100°C.

[0099] The adhesive layer of the bonded structure according to the invention can be formed from any type of adhesive suitable for bonding the selected substrate. Suitable adhesives can be one-component (1k) compositions or two-component (2k) compositions. Preferably, the adhesive layer is formed from adhesives selected from: epoxy adhesives, acrylic adhesives, polyurethane adhesives, cyanoacrylate adhesives, silicone adhesives, polyimide adhesives, silane-modified polymers, butyl rubber, hot melt adhesives, and mixtures thereof.

[0100] The present invention also relates to a method for debonding an adhesive structure according to the invention, the method comprising the steps of: i) applying heat; and ii) debonding the surfaces.

[0101] The heat source can be a heat source, an ultrasonic probe, or an electromagnetic source.

[0102] In the debonding method, the temperature applied in step i) is 60 to 200°C, and the duration of the heat application is preferably 2 to 60 minutes.

[0103] The heat-release adhesive composition according to the present invention can be used in various e-mobility components, such as battery covers, battery cells (cell-to-cell, cell-to-module, cell-to-vehicle), battery modules, inverters, converters, as well as in various structural adhesive applications and various thermal conductive applications.

[0104] Example Material 2k epoxy-based TEROSON 5056 from Henkel AG&Co. KGaA Thermally conductive adhesive (TCA, a product developed by Henkel) Bonderite M-NT 1455 W cleaning cloth from Henkel AG&Co. KGaA Glass beads from VWR (d = 1 mm) Isopropanol (iPrOH) from Labormagazin, Rötzmeier The substrates were: electrocoated steel (Rocholl e-coated Stahlprüfkörper #50725) with dimensions of 100 mm × 25 mm × 1.8 mm; and aluminum 3003 (Al3003, Rocholl Aluminiumprüfkörper #77467) with dimensions of 100 mm × 25 mm × 2.6 mm. The substrates were pretreated by rubbing them with a sheet of paper soaked in iPrOH and then allowing it to dry. For the Al3003 substrate, an additional wiping step was performed using a Bonderite M-NT 1455 W cloth to clean and prepare the surface, thereby removing any unwanted oxide layers.

[0105] Test method: The lap shear strength was measured using an STM 700.

[0106] Tensile shear strength was measured according to ASTM D1002.

[0107] Measure the tensile lap shear strength according to ISO 4587.

[0108] The substrate was prepared for measurement as follows: After pretreating the substrate (hereafter referred to as the “sample”) as reported above, the sample was assembled using the following procedure. Half of the pretreated sample was coated with a scraper using a 120 µm guide using the heat-release primer composition according to the invention (formulation details are in Table 1). The coated sample was cured in a Loctite UV-LED curing chamber equipped with a 365 nm LED, wherein the irradiation time was 150 seconds and the measured intensity was 320 mW / cm². 2 Once the samples have cured, the coating thickness for the coated specimens is 114 ± 11.7 µm. Using a wooden scraper, apply a 2.5 cm × 1 cm layer of adhesive (applied with glass beads to provide a 1 mm adhesive layer thickness) to the top portion of the specimen on the same side as the heat-release base composition according to the invention. A second specimen, uncoated and cleaned only with an iPrOH and / or Bonderite cloth, is first coated with a small amount of adhesive (2.5 cm × 0.2 cm) facing the first specimen containing the adhesive; and after removing excess adhesive, it is secured with two clamps. After repeating this procedure for all specimens, all samples are cured in an oven at 60°C for two hours.

[0109] Table 1 below lists the compositional details of the heat-release adhesive composition (composition 1) according to the present invention. The composition is prepared by mixing the components together.

[0110] Table 1

[0111] Example 1: Tensile shear strength of TEROSON EP 5065 and the heat-release primer composition according to the invention on electroplated metal in a temperature range of -40°C to 130°C. The lap shear strength of the combination of TEROSON EP 5065 and composition 1 was measured on electrocoated steel specimens within a temperature range of -40°C to 130°C. The results were... Figure 1 As shown in the image.

[0112] Above 80°C, the tensile shear strength decreased to 4.5 MPa, likely due to the weakening strength of the adhesive and primer at those temperatures. However, above 100°C, a 99% reduction in strength was recorded, which was attributed to the cracking of the adhesive layer caused by the expandable microspheres contained in Composition 1.

[0113] The efficiency of composition 1 was also evaluated while the sample was cooled to room temperature. The results were... Figure 2 As shown in the figure, the debonding efficiency decreases with decreasing temperature, down to 72% at room temperature. Adhesion failure was recorded in all cases.

[0114] Example 2 Evaluation of temperature propagation in a battery cell where this technology is primarily used during debinding. During the debonding process of the battery module, a key aspect is ensuring that the temperature of the battery cell does not exceed 70°C. For this reason, an initial debonding test was conducted using an empty battery casing, and the temperature was monitored during the test. The setup used in the test... Figure 3 The image shows the heating element used to heat the base coat and the cell. Next is a 1mm thick aluminum plate, required for applying Composition 1. Above Composition 1 is a 1mm thick structural adhesive, TEROSON EP 5065. Above all is a 0.5mm thick empty aluminum cell. T1 is the temperature of the heating element, T2 is the temperature of the UV base coat, T3 is the temperature of the adhesive layer, and T4 is the temperature of the cell.

[0115] Tests were conducted using a 200 µm dry layer of Composition 1 in combination with a structural adhesive (TEROSON EP 5065) or a thermal adhesive (a Henkel product). It is noteworthy that once Composition 1 expands due to the expansion of the expandable microspheres (approximately 90 to 100 °C), [the following is observed]. Figure 4 and 5 At approximately 200 seconds, the battery cell is heat-insulated. Although the temperature of the heating element rises, the battery cell remains below 70°C. Figure 4 and 5 ).

Claims

1. A heat-detachable primer composition, said heat-detachable primer composition comprising: a) Polyether urethane methacrylate resin; b) Two or more (meth)acrylate monomers; c) Thermally expandable thermoplastic microspheres; and d) One or more photoinitiators.

2. The heat-detachable primer composition according to claim 1, wherein the polyether urethane methacrylate resin is derived from a polyether polyol, hydrogenated bisphenol A, and toluene 2,4-diisocyanate having methacrylate functional groups.

3. The heat-detachable primer composition according to claim 1 or 2, wherein the polyether urethane methacrylate resin is present at 30 to 55% by weight, preferably 35 to 50% by weight, and more preferably 37 to 47% by weight of the total weight of the composition.

4. The heat-release primer composition according to any one of claims 1 to 3, wherein the two or more (meth)acrylate monomers are selected from butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecanyl (meth)acrylate, octadecyl (meth)acrylate, nonadecanyl (meth)acrylate, and meth)propylene. Eicosyl acrylate, Isobutyl methacrylate, Isoamyl methacrylate, Isohexyl methacrylate, Isoheptyl methacrylate, Isooctyl methacrylate, 2-Ethylhexyl methacrylate, sec-butyl methacrylate, 1-Methylbutyl methacrylate, 1-Ethylpropyl methacrylate, Tetrahydrofurfuryl methacrylate, Isobornyl methacrylate, Alkoxylated Tetrahydrofurfuryl methacrylate, Cyclotrimethylolpropane methyl acetal acrylate, 2-Phenoxyethyl methacrylate, Alkoxylated nonylphenol acrylate, Alkoxylated phenol acrylate, 2-(2-ethoxyethoxy)ethyl methacrylate, Alkoxylated lauryl acrylate Acrylates, stearyl (meth)acrylate, isodecyl (meth)acrylate, caprolactone (meth)acrylate, methoxy polyethylene glycol (350) monoacrylate and methoxy polyethylene glycol (550) monoacrylate, polyethylene glycol di(meth)acrylate, tetrahydrofuran (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylic acid, itaconic acid, hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, di(pentamethylene glycol) di(meth)acrylate Tetraethylene diethylene glycol di(meth)acrylate, diglyceride tetra(meth)acrylate, tetramethylene di(meth)acrylate, ethylene di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethoxylated bisphenol-A (meth)acrylate, and mixtures thereof; preferably selected from isobornyl methacrylate, hydroxyethyl methacrylate, methacrylic acid, itaconic acid, and mixtures thereof; more preferably selected from isobornyl methacrylate, hydroxyethyl methacrylate, methacrylic acid, and mixtures thereof; and even more preferably, two or more meth acrylate monomers are isobornyl acrylate, acrylic acid, and hydroxyethyl methacrylate.

5. The heat-detachable primer composition according to any one of claims 1 to 4, wherein the two or more (meth)acrylate monomers are present at 20 to 50% by weight, preferably 25 to 45% by weight, preferably 27 to 41% by weight, and more preferably 30 to 38% by weight of the total weight of the composition.

6. The heat-detachable base adhesive composition according to any one of claims 1 to 5, wherein the heat-expandable thermoplastic microspheres have a core-shell structure, and wherein the shell is formed of a crosslinked polymer and the core is composed of a foaming agent.

7. The heat-detachable primer composition according to any one of claims 1 to 6, wherein the heat-expandable thermoplastic microspheres expand when exposed to heat, preferably when exposed to heat of 60 to 200°C, preferably 80 to 160°C, more preferably 80 to 130°C.

8. The heat-detachable primer composition according to any one of claims 1 to 7, wherein the heat-expandable thermoplastic microspheres have a particle size of 5 to 100 μm, preferably 8 to 75 μm, preferably 9 to 50 μm, more preferably 10 to 30 μm, more preferably 12 to 20 μm, and even more preferably 13 to 19 μm, wherein the particle size is measured by laser diffraction (small-angle laser scattering LALLS).

9. The heat-detachable primer composition according to any one of claims 1 to 8, wherein the heat-expandable thermoplastic microspheres are present at 5 to 30% by weight, preferably 10 to 27% by weight, preferably 12 to 25% by weight, and more preferably 14 to 22% by weight, based on the total weight of the composition.

10. The heat-detachable primer composition according to any one of claims 1 to 9, wherein the one or more photoinitiators are selected from 1-hydroxycyclohexylphenyl ketone, ethyl(2,4,6-trimethylbenzoyl)-phenylphosphine ester, 2-hydroxy-2-methyl-1-phenyl-prop-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl-ketone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylprop-1-one, 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinylphenyl)-1-butanone, 1-hydroxycyclohexylphenyl ketone and diphenyl Combinations of methyl ketones, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenyl-1-propane, combinations of 2,4,6-trimethylbenzoyl diphenylphosphine oxide and 2-hydroxy-2-methyl-1-phenyl-prop-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-prop-1-one, 50 wt% diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and 50 wt% 2-hydroxy-2-methyl-1-phenyl-1-propanone, combinations of bis(2,6-dimethoxybenzoyl-2,4,4-trimethylpentyl)phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-prop-1-one, bis(η <5> -2,4-cyclopentadien-1-yl)-bis[2,6-difluoro-3-(1H-pyrrolo-1-yl)phenyl]titanium, 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone, dl-camphorquinone, and mixtures thereof; preferably selected from ethyl (2,4,6-trimethylbenzoyl)-phenyl)phosphine ester, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-prop-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl-ketone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and mixtures thereof; and more preferably selected from ethyl (2,4,6-trimethylbenzoyl)-phenyl)phosphine ester, 1-hydroxycyclohexylphenyl ketone, and mixtures thereof.

11. The heat-detachable primer composition according to any one of claims 1 to 10, wherein the one or more photoinitiators are present at 0.5 to 10% by weight, preferably 1.25 to 8% by weight, more preferably 1.5 to 5% by weight, based on the total weight of the composition.

12. A cured heat-detachable primer composition according to any one of claims 1 to 11, wherein the heat-detachable primer composition is cured by photocuring.

13. Use of the heat-detachable primer composition according to any one of claims 1 to 11 or the cured product according to claim 12 in bonded structures.

14. An adhesive structure, said adhesive structure comprising: First substrate; Second substrate; The heat-detachable primer composition layer according to any one of claims 1 to 11 or the cured product layer according to claim 12; as well as Adhesive layer, The heat-detachable primer is disposed on the surface of the first substrate and / or the surface of the second substrate, and the adhesive layer is placed on top of the heat-detachable primer layer.

15. The bonded structure of claim 14, wherein the adhesive layer is formed of an adhesive selected from the group consisting of epoxy adhesives, acrylic adhesives, polyurethane adhesives, cyanoacrylate adhesives, silicone adhesives, polyimide adhesives, silane-modified polymers, butyl rubber, hot melt adhesives, and mixtures thereof.

16. A method for debonding an bonded structure according to claim 14 or 15, the method comprising the steps of: i) Apply heat; as well as ii) De-adhere the surface. The temperature applied in step i) is preferably 60 to 200°C, and the duration of the heat application is preferably 2 to 60 minutes.

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