Multi-layer tape and method for debonding multi-layer tape

Abstract

The invention relates to a multilayer tape comprising at least the following sequence of layers: (a1) an adhesive layer containing a blowing agent; (b1) a laser-permeable adhesive layer; (c) a laser debondable layer comprising a laser sensitive material selected from the group consisting of metals, metal oxides, carbon black, and radiation curable paints; and (b2) a laser-transmitting adhesive layer. Furthermore, the invention relates to a method for debonding the multilayer tape. In addition, the invention relates to the use of the multilayer tape in electronic, automotive, medical and dental devices.

Description

Technical Field

[0001] The present invention relates to a multilayer tape and a multilayer assembly comprising the multilayer tape. Furthermore, the present invention relates to a method for debonding the multilayer tape in the multilayer assembly. Furthermore, the present invention relates to the use of the multilayer tape in electronic devices, automotive devices, medical devices and dental devices. Background Art

[0002] The ability to separate the assembly of adhesive bonding when substrate is not damaged is highly desirable. In many applications, for example in electronic equipment, automotive equipment, medical equipment, dental equipment and general manufacturing, the opportunity of separating the assembly is important. This can be used for repositioning in manufacturing, repairing in use or recycling materials at the end of the life span. The whole bag of tricks for adhesive reversibility or debonding has been proposed in the past 40 years, but there is no generally accepted solution for the adhesive application of debonding on demand at present. For example, C.Sato, in Recyicling and environmental aspects, 2011, 58, describes several methods for debonding the adherend for making adhesive bonding in the 1506-1526 pages, including infrared, induction and microwave heating.

[0003] However, one of the major challenges with these adhesives is that the adhesive bonded joint is not easily separated without damaging the adherend if the adhesive bonded joint is bonded with a strong adhesive or has a large bond area.

[0004] Thus, there remains a need for multilayer tapes having unique properties, particularly with respect to their use in electronic, automotive, medical, and dental devices. DETAILED DESCRIPTION

[0005] The object of the present invention is therefore to provide a novel multilayer tape which will be easily separated from an adhesively bonded adherend without damaging the adhesively bonded adherend. This object is solved by a multilayer tape according to the invention having the features of the independent claims. Preferred embodiments which can be realized individually or in combination are presented in the description and in the dependent claims. In particular, it has been unexpectedly found that such a multilayer tape is debondable, in particular clean residues from each side of the substrate at an Mpa bond strength level.

[0006] The present invention therefore relates to a multilayer tape comprising at least the following layer sequence:

[0007] (a1) an adhesive layer containing a foaming agent;

[0008] (b1) laser-transmitting adhesive layer;

[0009] (c) a laser releasable layer comprising a laser sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation curable lacquers; and

[0010] (b2) Laser-transmitting adhesive layer.

[0011] According to another alternative, it is preferred that the multilayer tape comprises at least the following layer sequence:

[0012] (a1) an adhesive layer containing a foaming agent;

[0013] (b1) laser-transmitting adhesive layer;

[0014] (c) a laser-releasable layer comprising a laser-sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation-curable lacquers;

[0015] (b2) a laser-transmitting adhesive layer; and

[0016] (a2) Adhesive layer containing a foaming agent.

[0017] It is further preferred that the adhesive layer containing a blowing agent according to (a1) and / or (a2) comprises a polymer compound, preferably, wherein the polymer compound is a pressure-sensitive adhesive, more preferably, the polymer compound is selected from poly(meth)acrylates, polyurethanes, natural rubbers, synthetic rubbers and silicones, preferably poly(meth)acrylates and polyurethanes, more preferably poly(meth)acrylates.

[0018] All pressure-sensitive adhesives known to the person skilled in the art can be used as the pressure-sensitive adhesive for the adhesive layer containing a blowing agent according to (a1) and / or (a2), for example those based on acrylates and / or methacrylates, polyurethanes, natural rubbers, synthetic rubbers, styrene block copolymers with elastomer blocks made of unsaturated or hydrogenated polydiene blocks (polybutadiene, polyisoprene, copolymers of both and other elastomer blocks familiar to the person skilled in the art), polyolefins, fluoropolymers and / or silicones. This also includes other adhesives having the properties of pressure-sensitive adhesives according to the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (Satas & Associates, Warwick 1999).

[0019] Preferably, the adhesive layer containing a blowing agent according to (a1) and / or (a2) is obtainable or obtained by crosslinking (meth)acrylates with acrylamides, preferably by crosslinking n-butyl acrylate with N-vinyl caprolactam to obtain copolymers. The copolymers can be prepared in a manner known to those skilled in the art by means of free radical polymerization in a solvent mixture of ethyl acetate / isopropanol (168 / 1).

[0020] Furthermore, it is preferred that the foaming agent-containing adhesive layer according to (a1) and / or (a2) comprises a foaming agent, preferably, wherein the foaming agent is selected from diazene compounds, preferably azodicarbonamide; hydrazine compounds, preferably p-toluenesulfonylhydrazide and 4,4'-oxybis(benzenesulfonylhydrazide); sulfonylsemicarbazide compounds, preferably p-toluenesulfonylsemicarbazide; tetrazole compounds, preferably 5-phenyl-1H-tetrazole; carbonate compounds, preferably sodium bicarbonate and zinc carbonate; and microspheres, preferably heat-expandable microspheres.

[0021] Heat-expandable microspheres comprising a thermoplastic polymer shell and a propellant encapsulated therein are commercially available, for example as In such microspheres, the propellant is usually a liquid having a boiling point not higher than the softening temperature of the thermoplastic polymer shell. The softening temperature of the polymer shell (usually corresponding to its glass transition temperature T g ) is preferably in the range of 0 to 140° C., more preferably 30 to 100° C. When heated, the propellant evaporates, thereby increasing the internal pressure, and at the same time the shell softens, which leads to a significant increase in the size of the microspheres. The temperature at which the expansion begins is called T 开始 , and the temperature at which the maximum expansion is reached is called T 最大 . T of expandable microspheres 开始 Preferably, it is 40 to 140° C., most preferably, it is 50 to 100° C. The T of the expandable microspheres 最大 Higher than T 开始 , and preferably 80 to 200°C, most preferably 100 to 170°C.

[0022] The adhesive layer containing a blowing agent according to (a1) and / or (a2) preferably contains microspheres which in the unexpanded state have an average diameter of 3 μm to 30 μm, in particular 5 μm to 20 μm at 25° C. and / or have an average diameter of 10 μm to 200 μm, in particular 15 μm to 90 μm after expansion. The average diameter of the unexpanded (non-expanded) microspheres is preferably lower than the layer thickness of the adhesive layer containing a blowing agent according to (a1) and / or (a2).

[0023] Regarding the laser-transmitting adhesive layer according to (b1) and / or (b2), it is preferred that the laser-transmitting adhesive layer according to (b1) and / or (b2) comprises a pressure-sensitive adhesive composition, preferably, wherein the laser-transmitting adhesive layer according to (b1) and / or (b2) comprises at least 40 wt % of poly(meth)acrylate, based on 100 wt % of the pressure-sensitive adhesive composition.

[0024] The laser-transmissive adhesive layer according to (b1) and / or (b2) preferably comprises at least one polymer selected from the group consisting of poly(meth)acrylates, natural rubbers, synthetic rubbers, in particular vinyl aromatic block copolymers, silicones, polyurethanes and mixtures of two or more of the polymers listed above. The laser-transmissive adhesive layer according to (b1) and / or (b2) more preferably comprises at least one poly(meth)acrylate. In particular, the laser-transmissive adhesive layer according to (b1) and / or (b2) contains no further polymers in addition to one or more poly(meth)acrylates.

[0025] It is further preferred that the laser-transmissive adhesive layer according to (b1) and / or (b2) comprises at least the following two components:

[0026] 60% to 90% by weight, preferably 65% ​​to 80% by weight, of the adhesive of the first polymer component based on polyacrylate; and

[0027] - 10 wt. % to 40 wt. %, preferably 15 wt. % to 30 wt. % of an adhesive composition (adhesive composition) of a second elastomer-based polymer component, more preferably a synthetic rubber, the second elastomer-based polymer component being substantially immiscible (compatible) with the polyacrylate component.

[0028] Preferably, the laser-transmissive adhesive layer according to (b1) and / or (b2) comprises a heat-activated adhesive composition. Further preferably, the laser-transmissive adhesive layer according to (b1) and / or (b2) can be manufactured under the trade name tesa 8474 is commercially available as a reactive heat activated structural adhesive film based on phenolic resin and nitrile rubber. This amber double-sided tape has no backing. It is protected by a sturdy paper liner.

[0029] Preferably, the laser-transmissive adhesive layer according to (b1) and / or (b2) comprises a heat-activated adhesive composition disclosed and described in detail in WO 2013 / 174650 A1.

[0030] Furthermore, it is preferred that the heat-activated adhesive composition comprises 30 to 75 wt % of the epoxy resin and 25 to 70 wt % of the nitrile rubber, based on 100 wt % of the heat-activated adhesive composition.

[0031] The nitrile rubber preferably comprises an acrylonitrile content of 15 to 45% by weight. Preferably, the nitrile rubber has a Mooney viscosity of less than 100 (Mooney ML 1+4 at 100° C.; corresponding to DIN 53523). Commercial examples of such nitrile rubbers are, for example, Nipol from Zeon Chemicals. TMN917. It is further preferred that the epoxy resin is a short-chain to medium-chain oligomer or polymeric compound, in particular having an average molecular weight in the range of up to 10,000 g / mol. The proportion of the epoxy resin in the heat-activated adhesive composition is preferably between 75 and 30% by weight. For polymeric epoxy resins, the weight-average molecular weight Mw of the epoxy resin varies between 100 g / mol and a maximum of 10,000 g / mol. Epoxy resins include, for example, reaction products of bisphenol A with epichlorohydrin (epichlorohydrin), epichlorohydrin, glycidyl esters, reaction products of epichlorohydrin with p-aminophenol.

[0032] Preferably, the epoxy resin is selected from epichlorohydrin and glycidyl esters.

[0033] Preferred commercial examples of epoxy resins are Araldite® from Ciba Geigy. TM 6010、CY-281 TM 、ECN TM 1273、ECN TM 1280, MY 720, RD-2, DER from Dow Chemical TM 331、DER TM 732、DER TM 736, DEN TM 432、DEN TM 438、DEN TM 485, Epon from Shell Chemical TM 812, 825, 826, 828, 830, 834, 836, 871, 872, 1001, 1004, 1031, etc. and HPT also from Shell Chemical TM 1071、HPT TM 1079.

[0034] Examples of commercially available aliphatic epoxy resins are vinyl cyclohexane dioxide, such as ERL-4206, ERL-4221, ERL 4201, ERL-4289 or ERL-0400 from Union Carbide Corp.

[0035] Examples of novolac resins that may be used are Epi-Rez from Celanese. TM 5132, ESCN-001 from Sumitomo Chemical, CY-281 from Ciba Geigy, DEN from Dow Chemical TM 431、DEN TM438, Quatrex 5010, RE 305S from Nippon Kayaku, Epicion from DaiNipon Ink Chemistry TM N673 or Epicotate from Shell Chemical TM 152.

[0036] In addition, melamine resins, such as Cymel from Cytec TM 327 and 323 can also be used as heat activated adhesive compositions.

[0037] For example, novolac resins, phenolic resole resins or combinations of novolac resins and phenolic resins are suitable. Examples of commercially available phenolic resins are YP 50 from Toto Kasei, PKHC from Union Carbide Corp and BKR 2620 from Showa Union Gosei Corp.

[0038] Terpene-phenolic resins such as NIREZ from Arizona Chemical TM 2019 is also available as a reactive resin.

[0039] In addition, polyisocyanates such as Coronate from Nippon Polyurethane Ind. TM L. Desmodur from Bayer TM N3300 or Mondur TM 489 can also be used as a reactive resin.

[0040] It is further preferred that the heat-activated adhesive composition comprises (tackifying) resins that enhance tackiness with a ratio of up to 30% by weight, based on the total mixture of the heat-activated adhesive composition. All known tackifying resins described in the literature can be used without exception as tackifying resins to be added. Pinene, indene and rosin resins, their disproportionated, hydrogenated, polymerized, esterified derivatives and salts, aliphatic and aromatic hydrocarbon resins, terpene resins and terpene-phenolic resins and C5-, C9- and other hydrocarbon resins. Any combination of these and other resins can be used to set the property of the heat-activated adhesive composition as required. Usually, all (soluble) resins compatible with nitrile rubber can be used, particularly all aliphatic, aromatic, alkyl aromatic hydrocarbon resins, hydrocarbon resins based on pure monomers, hydrogenated hydrocarbon resins, functional hydrocarbon resins and natural resins. Clearly with reference to the statement of the state of knowledge in " Handbook of Pressure Sensitive Adhesive Technology " (van Nostrand, 1989) of Donatas Satas. In order to accelerate the reaction between the two components, optional crosslinking agents and accelerators may also be added to the mixture. Examples of suitable accelerators are imidazoles commercially available as 2M7, 2E4MN, 2PZ-CN, 2PZ-CNS, P0505, L07N from Shikoku Chem. or as Curezol 2MZ from Air Products. HMTA (hexamethylenetetramine) additives are also suitable as crosslinking agents. In addition, amines, in particular tertiary amines, may also be used for acceleration. In addition to reactive resins, plasticizers may also be used.

[0041] In a preferred embodiment of the present invention, plasticizers based on polyethylene glycol ethers, polyethylene oxides, phosphates, aliphatic carboxylates and benzoates can be used. In addition, aromatic carboxylates, higher molecular weight diols, sulfonamides and adipic acid esters can also be used. In another preferred embodiment, additional additives are added to the blend, such as polyvinyl formal, polyacrylate rubber, chloroprene rubber, ethylene-propylene-diene rubber, methyl-vinyl-silicone rubber, fluorosilicone rubber, tetrafluoroethylene-propylene copolymer rubber, butyl rubber, styrene-butadiene rubber. Polyvinyl butyral can be Butvar from Solutia. TM 、Wacker's Pioloform TM and Kuraray's Mowital TM Polyacrylate rubber is available under the trade name Nipol AR TM Available from Zeon. Neoprene can be Baypren TM Available from Bayer. Ethylene-propylene-diene rubber can be Keltan TM Purchased from DSM as VistaionTM Purchased from Exxon Mobile and Buna EP TM Available from Bayer. Methyl vinyl silicone rubber can be obtained from Dow Corning's Silastic TM and GE Silicones' Silopren TM Fluorosilicone rubber can be obtained. TM The brand is available from GE Silicones. Butyl rubber is available under the trade name Esso Butyl TM Available from Exxon Mobile. Styrene-butadiene rubber can be Buna S from Bayer TM and Eni Chem's Europrene TM and Bayer's Polysar S TM Polyvinyl formal can be obtained from Formvar TM Purchased from Ladd Research.

[0042] It is further preferred that the laser transparent adhesive layer according to (b1) and / or (b2) comprises a heat activated adhesive composition disclosed and described in detail in WO 2010 / 245945A1. It is preferred that the heat activated adhesive composition comprises nitrile rubber and phenolic novolac resin.

[0043] Furthermore, it is preferred that the heat-activated adhesive composition includes 20 to 70 wt % of the phenolic resin and 30 to 80 wt % of the nitrile rubber, based on 100 wt % of the heat-activated adhesive composition.

[0044] Preferably, the heat-activated adhesive composition comprises an acrylonitrile-butadiene copolymer and a phenolic novolac resin. The ratio of acrylonitrile-butadiene copolymer to phenolic novolac resin is preferably in the range of 3:7 to 8:2. The phenolic novolac resin can be chemically crosslinked at high temperatures in the presence of a curing agent. The crosslinking is carried out in particular only by a chemical reaction of the phenolic novolac resin with the curing agent by heating. The activation temperature for thermal crosslinking is much higher than room temperature, typically at least 100° C. or more. The preferred activation temperature for thermal crosslinking (in particular to ensure the required bond strength) is at least 120° C., in particular between 140° C. and 220° C.

[0045] In particular, all acrylonitrile-butadiene rubbers having an acrylonitrile content of 15 to 55% by weight can be used as acrylonitrile-butadiene copolymers. Copolymers of acrylonitrile-butadiene and isoprene can also be used. The proportion of 1,2-linked butadiene is variable. The aforementioned polymers can be hydrogenated to varying degrees; fully hydrogenated polymers having a double bond proportion of less than 1% can also be used. Such rubbers are commercially available, for example, under the name EuropreneTM Purchased from Eni Chem under the name Krynac TM and Perbunan TM Available from Bayer or from Zeon as Nipol and Breon, hydrogenation systems are available from Zeon under the name Zetpol or from Lanxess in various grades as Therban.

[0046] Nitrile rubber can be dissolved or suspended in short-chain alcohols and ketones such as ethanol or butanone. Butanone is preferred here because the remaining components, especially the novolac resin, can be better dissolved in butanone.

[0047] Novolacs are soluble, meltable, non-self-curing and storage-stable phenolic resins. They are prepared by condensing formaldehyde and excess phenol in the presence of an acidic catalyst. They are crosslinked into thermosetting plastic molded parts with the help of curing agents that decompose formaldehyde, such as hexamethylenetetramine (urotropine). Due to steric hindrance, this crosslinking is carried out faster in the para position than in the ortho position. For this reason, preferably novolac resins are used, which contain phenol units connected to each other in the ortho position to crosslink particularly quickly.

[0048] Examples of novolac resins are, for example, the Durez products of Sumitomo Bakelite and / or the Plenco products of Plastics Engineering Company. Various formaldehyde donors can be used as curing agents, for example hexamethylenetetramine (Hexa, HMTA, hexamethylenetetramine) and / or various hydroxymethylamine derivatives, for example trimethylolmelamine or hexamethylolmelamine. Chemical crosslinking of the curing agent with the novolac resin results in very high strength within the adhesive film. However, the bond strength to polyimide is also very high.

[0049] To increase adhesion, it is also possible in an advantageous procedure to add adhesive resins ("tackifiers") which are compatible with the elastomer. Tackifiers that can be used for heat-activated adhesives include, for example, non-hydrogenated, partially or fully hydrogenated resins based on rosin and rosin derivatives, hydrogenated polymers of dicyclopentadiene, non-hydrogenated, partially, selectively or fully hydrogenated hydrocarbon resins based on C5-, C5 / C9- or C9-monomer streams, polyterpene resins based on α-pinene and / or β-pinene and / or δ-limonene, preferably hydrogenated polymers of pure C8- and C9-aromatic compounds. The above-mentioned adhesive resins can be used individually or in mixed form. Advantageously, up to 20% by weight of tackifier, based on the adhesive, can be added. Monomers and oligomeric compounds having more than one epoxy group per molecule are understood to be epoxy resins. These can be reaction products of glycidyl esters or epichlorohydrin with bisphenol A or bisphenol F or mixtures of the two.

[0050] Epoxy novolac resins obtained by reacting epichlorohydrin with a reaction product of phenol and formaldehyde may also be used. Monomeric compounds having several epoxy terminal groups, which act as diluents for epoxy resins, may also be used. Elastomerically modified epoxy resins may also be used. An example of an epoxy resin that may be advantageously used is Araldite from Ciba Geigy. TM 6010、CY-281 TM 、ECN TM 1273、ECN TM 1280, MY 720, RD-2, DER from Dow Chemicals TM 331, 732, 736, DEN TM 432, Epon from Shell Chemicals TM 812, 825, 826, 828, 830, etc., also from Shell Chemicals' HPT TM 1071, 1079, Bakelite from Bakelite AG TM EPR 161, 166, 172, 191, 194, etc. Commercial aliphatic epoxy resins which can be advantageously used are, for example, vinylcyclohexane dioxide, for example ERL-4206, 4221, 4201, 4289 or 0400 from Union Carbide Corp.

[0051] Advantageously usable elastomeric epoxy resins are available from Noveon under the name Hycar. Advantageously usable epoxide diluents, monomeric compounds having several epoxide groups, are for example Bakelite AG from Bakelite TM EPD KR, EPD Z8, EPD HD, EPD WF, etc. or Polypox from UCCP TM R9, R12, R15, R19, R20, etc.

[0052] The following additives may be used in addition: primary antioxidants such as sterically hindered phenols, secondary (secondary) antioxidants such as phosphites or thioethers, other antioxidants such as sterically hindered amines, process stabilizers such as C free radical scavengers, light stabilizers such as UV absorbers, processing aids, fillers such as silicon dioxide, glass (ground or beaded form), aluminum oxide, zinc oxide, titanium dioxide, carbon black, metal powders, etc., color pigments and dyes and fluorescent whitening agents, optional other polymers, preferably other polymers with elastomeric properties. The above-mentioned additives and, if appropriate, other additives may be used alone or in combination with each other. The elasticity of the adhesive may be increased by using a plasticizer. For example, low molecular weight polyisoprene, polybutadiene, polyisobutylene or polyethylene glycol and polypropylene glycol may be used as plasticizers.

[0053] It is further preferred that the phenolic resin comprises phenol and formaldehyde.

[0054] Preferably, the laser debondable layer according to (c) is disclosed and described in detail in DE 102020209557A1. With regard to the laser debondable layer according to (c), it is preferred that the laser sensitive material comprises a metal, preferably, wherein the metal is selected from Al, Cu, Ag, Au, Pt, Pd, Zn, Cr and Ti, preferably Al, Cu and Ti, more preferably Al.

[0055] It is further preferred that the laser sensitive material comprises a metal oxide, preferably, wherein the metal oxide is selected from silicon dioxide, titanium dioxide and tin zinc oxide, preferably titanium dioxide.

[0056] Furthermore, it is preferred that the laser-sensitive material comprises carbon black.

[0057] Preferably, the laser-sensitive material comprises a radiation-curable lacquer, preferably wherein the radiation-curable lacquer comprises a urethane acrylate.

[0058] It is further preferred that the urethane acrylate comprises a difunctional or higher functional urethane acrylate oligomer, and more preferably, the difunctional or higher functional urethane acrylate oligomer comprises

[0059] (I) 40 to 90 wt % of a difunctional or higher functional urethane acrylate oligomer A;

[0060] (II) 5 to 20% by weight of a difunctional or higher-functional acrylic monomer B; and

[0061] (III) 5 to 20% by weight of a difunctional glycol monomer C.

[0062] Preferably, the difunctional or higher-functional urethane acrylate oligomer A comprises urethane tri(meth)acrylate.

[0063] Furthermore, it is preferred that the difunctional or higher-functional acrylic monomer B is selected from propoxylated glyceryl tri(meth)acrylate, ethoxylated glyceryl tri(meth)acrylate, propoxylated trimethylolpropane glyceryl (meth)acrylate and ethoxylated trimethylolpropane glyceryl (meth)acrylate.

[0064] Furthermore, it is preferred that the difunctional glycol monomer C is selected from ethylene glycol diacrylate and propylene glycol diacrylate, and preferably, the difunctional triethylene glycol monomer C includes triethylene glycol diacrylate.

[0065] There is no particular limitation on the thickness of the laser debondable layer according to (c). Preferably, the laser debondable layer according to (c) has a thickness in the range of 10 nm to 100 μm.

[0066] Preferably, the laser debondable layer according to (c) has a thickness in the range of 0.5 μm to 100 μm, preferably in the range of 1 μm to 30 μm, more preferably in the range of 2 μm to 25 μm.

[0067] Furthermore, it is preferred that the laser debondable layer according to (c) has a thickness in the range of 10 nm to 1000 nm, preferably in the range of 10 nm to 500 nm, more preferably in the range of 20 nm to 100 nm.

[0068] According to another alternative, the multilayer tape comprises at least the following layer sequence:

[0069] (a1) an adhesive layer containing a foaming agent;

[0070] (b1) laser-transmitting adhesive layer;

[0071] (d1) laser-transparent intermediate layer;

[0072] (c) a laser releasable layer comprising a laser sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation curable lacquers; and

[0073] (b2) Laser-transmitting adhesive layer.

[0074] According to another alternative, the multilayer tape comprises at least the following layer sequence:

[0075] (a1) an adhesive layer containing a foaming agent;

[0076] (b1) laser-transmitting adhesive layer;

[0077] (d1) laser-transparent intermediate layer;

[0078] (c) a laser-releasable layer comprising a laser-sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation-curable lacquers;

[0079] (d2) a laser-transparent intermediate layer; and

[0080] (b2) Laser-transmitting adhesive layer.

[0081] According to another alternative, the multilayer tape comprises at least the following layer sequence:

[0082] (a1) an adhesive layer containing a foaming agent;

[0083] (b1) laser-transmitting adhesive layer;

[0084] (d1) laser-transparent intermediate layer;

[0085] (c) a laser-releasable layer comprising a laser-sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation-curable lacquers;

[0086] (b2) a laser-transmitting adhesive layer; and

[0087] (a2) Adhesive layer containing a foaming agent.

[0088] According to another alternative, the multilayer tape comprises at least the following layer sequence:

[0089] (a1) an adhesive layer containing a foaming agent;

[0090] (b1) laser-transmitting adhesive layer;

[0091] (d1) laser-transparent intermediate layer;

[0092] (c) a laser-releasable layer comprising a laser-sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation-curable lacquers;

[0093] (d2) middle layer;

[0094] (b2) a laser-transmitting adhesive layer; and

[0095] (a2) Adhesive layer containing a foaming agent.

[0096] It is further preferred that the laser transparent intermediate layer according to (d1) and / or (d2) comprises a polymer, wherein the polymer is selected from polyethylene terephthalate (PET), polyethylene (PE), polyamide (PA) or polypropylene (PP), preferably polyethylene terephthalate (PET).

[0097] It is further preferred that the multilayer tape further comprises one or more release liners.

[0098] Furthermore, the invention relates to a multilayer assembly comprising a multilayer tape according to any one of claims 1 to 28 and one or more adherends.

[0099] Preferably, the one or more stickers are laser transparent.

[0100] Furthermore, the present invention relates to a method for debonding a multilayer tape according to any one of claims 1 to 28, comprising:

[0101] - subjecting the multilayer assembly according to claim 29 or 30 to a temperature in the range of 40° C. to 200° C. for a period in the range of 1 to 100 minutes; and / or

[0102] - subjecting the multilayer assembly according to claim 29 or 30 to laser light for a period of time in the range from 0.1 seconds to 10 minutes; and

[0103] - separating the multilayer tape from the one or more adherends.

[0104] It is further preferred that the debonding comprises effecting expansion of the adhesive layer containing a blowing agent according to (a1) and / or (a2).

[0105] It is further preferred that the debonding comprises subjecting the adhesive layer containing a blowing agent according to (a1) and / or (a2) to laser, heat or plasma.

[0106] Furthermore, it is preferred that the debonding comprises effecting oxidation and / or sublimation of the laser debondable layer according to (c).

[0107] Preferably, the laser is an infrared laser, preferably wherein the laser exhibits light having a wavelength in the range of 750 nm to 1400 nm.

[0108] Furthermore, the invention relates to the use of the multilayer tape according to any one of claims 1 to 28 in electronic devices, automotive devices, medical devices and dental devices.

[0109] The invention is further illustrated by the following set of embodiments and combinations of the embodiments resulting from the indicated dependencies and back-references. In particular, it should be noted that in various cases where a series of embodiments is mentioned, for example in the context of a term such as "a multilayer tape according to any one of embodiments 1 to 5", each embodiment within the scope is intended to be explicitly disclosed to the skilled person, i.e. the wording of the term should be understood by the skilled person as being synonymous with "a multilayer tape according to any one of embodiments 1, 2, 3, 4 and 5". Furthermore, it should be explicitly noted that the following set of embodiments is not a set of claims determining the scope of protection, but rather represents a properly structured part of the description of general and preferred aspects of the invention.

[0110] 1. A multilayer belt, comprising at least the following sequence of layers:

[0111] (a1) an adhesive layer containing a foaming agent;

[0112] (b1) laser-transmitting adhesive layer;

[0113] (c) a laser releasable layer comprising a laser sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation curable lacquers; and

[0114] (b2) Laser-transmitting adhesive layer.

[0115] 2. The multilayer tape of embodiment 1 comprises at least the following layer sequence:

[0116] (a1) an adhesive layer containing a foaming agent;

[0117] (b1) laser-transmitting adhesive layer;

[0118] (c) a laser-releasable layer comprising a laser-sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation-curable lacquers;

[0119] (b2) a laser-transmitting adhesive layer; and

[0120] (a2) Adhesive layer containing a foaming agent.

[0121] 3. The multilayer tape of embodiment 1 or 2, wherein the foaming agent-containing adhesive layer according to (a1) and / or (a2) comprises a polymer compound, preferably, wherein the polymer compound is selected from poly(meth)acrylates, polyurethanes, natural rubbers, synthetic rubbers and silicones, preferably poly(meth)acrylates and polyurethanes, more preferably poly(meth)acrylates.

[0122] 4. The multilayer tape according to any one of embodiments 1 to 3, wherein the foaming agent-containing adhesive layer according to (a1) and / or (a2) is obtainable or obtained by crosslinking (meth)acrylate with acrylamide, preferably by crosslinking n-butyl acrylate with N-vinylcaprolactam.

[0123] 5. The multilayer tape of any one of embodiments 1 to 4, wherein the foaming agent-containing adhesive layer according to (a1) and / or (a2) comprises a foaming agent, preferably, wherein the foaming agent is selected from diazene compounds, preferably azodicarbonamide; hydrazine compounds, preferably p-toluenesulfonylhydrazide and 4,4'-oxybis(benzenesulfonylhydrazide); sulfonylsemicarbazide compounds, preferably p-toluenesulfonylsemicarbazide; tetrazole compounds, preferably 5-phenyl-1H-tetrazole; carbonate compounds, preferably sodium bicarbonate and zinc carbonate, and microspheres, preferably heat-expandable microspheres.

[0124] 6. The multilayer tape of any one of embodiments 1 to 5, wherein the laser-transmissive adhesive layer according to (b1) and / or (b2) comprises a pressure-sensitive adhesive composition, preferably, wherein the laser-transmissive adhesive layer according to (b1) and / or (b2) comprises at least 40 wt % of poly(meth)acrylate, based on 100 wt % of the pressure-sensitive adhesive composition.

[0125] 7. The multilayer tape of any one of embodiments 1 to 6, wherein the laser-transmissive adhesive layer according to (b1) and / or (b2) comprises a heat-activated adhesive composition.

[0126] 8. The multilayer tape of embodiment 7, wherein the heat activated adhesive composition comprises 30 to 75 weight percent epoxy resin and 25 to 70 weight percent nitrile rubber, based on 100 weight percent of the heat activated adhesive composition.

[0127] 9. The multilayer tape of embodiment 8, wherein the epoxy resin is selected from epichlorohydrin and glycidyl esters.

[0128] 10. The multilayer tape of embodiment 7, wherein the heat activated adhesive composition comprises 20 to 70 weight percent phenolic resin and 30 to 80 weight percent nitrile rubber, based on 100 weight percent of the heat activated adhesive composition.

[0129] 11. The multilayer tape of embodiment 10, wherein the phenolic resin comprises phenol and formaldehyde.

[0130] 12. The multilayer tape of any one of embodiments 1 to 11, wherein the laser sensitive material comprises a metal, preferably, wherein the metal is selected from the group consisting of Al, Cu, Ag, Au, Pt, Pd, Zn, Cr and Ti, preferably Al, Cu and Ti, more preferably Al.

[0131] 13. The multilayer tape of any one of embodiments 1 to 11, wherein the laser-sensitive material comprises a metal oxide, preferably, wherein the metal oxide is selected from silicon dioxide, titanium dioxide and tin zinc oxide, preferably titanium dioxide.

[0132] 14. The multilayer tape of any of embodiments 1 to 11, wherein the laser-sensitive material comprises carbon black.

[0133] 15. The multilayer tape of any of embodiments 1 to 11, wherein the laser sensitive material comprises a radiation curable lacquer, preferably wherein the radiation curable lacquer comprises a urethane acrylate.

[0134] 16. The multilayer tape of embodiment 15, wherein the urethane acrylate comprises a difunctional or higher functional urethane acrylate oligomer, more preferably, the difunctional or higher functional urethane acrylate oligomer comprises

[0135] (I) 40 to 90 wt % of a difunctional or higher functional urethane acrylate oligomer A;

[0136] (II) 5 to 20% by weight of a difunctional or higher-functional acrylic monomer B; and

[0137] (III) 5 to 20% by weight of a difunctional glycol monomer C.

[0138] Claim 3 of 2021059 / DE.

[0139] 17. The multilayer tape of embodiment 16, wherein the difunctional or higher functional urethane acrylate oligomer A comprises polyurethane tri(meth)acrylate.

[0140] 18. The multilayer tape of embodiment 16, wherein the difunctional or higher-functional acrylic monomer B is selected from propoxylated glyceryl tri(meth)acrylate, ethoxylated glyceryl tri(meth)acrylate, propoxylated trimethylolpropane glyceryl (meth)acrylate and ethoxylated trimethylolpropane glyceryl (meth)acrylate.

[0141] 19. The multi-layer tape of embodiment 16, wherein the difunctional glycol monomer C is selected from ethylene glycol diacrylate and propylene glycol diacrylate, and preferably, the difunctional triethylene glycol monomer C comprises triethylene glycol diacrylate.

[0142] 20. The multilayer tape of any one of embodiments 1 to 19, wherein the laser debondable layer according to (c) has a thickness in the range of 10 nm to 100 μm.

[0143] 21. The multilayer tape of any one of embodiments 1 to 20, wherein the laser debondable layer according to (c) has a thickness in the range of 0.5 to 100 μm, preferably in the range of 1 to 30 μm, more preferably in the range of 2 to 25 μm.

[0144] 22. The multilayer tape of any one of embodiments 1 to 20, wherein the laser debondable layer according to (c) has a thickness in the range of 10 to 1000 nm, preferably in the range of 10 to 100 nm, more preferably in the range of 20 to 100 nm.

[0145] 23. The multilayer tape of any one of embodiments 1 to 22, comprising at least the following layer sequence:

[0146] (a1) an adhesive layer containing a foaming agent;

[0147] (b1) laser-transmitting adhesive layer;

[0148] (d1) laser-transparent intermediate layer;

[0149] (c) a laser releasable layer comprising a laser sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation curable lacquers; and

[0150] (b2) Laser-transmitting adhesive layer.

[0151] 24. The multilayer tape of any one of embodiments 1 to 23, comprising at least the following layer sequence:

[0152] (a1) an adhesive layer containing a foaming agent;

[0153] (b1) laser-transmitting adhesive layer;

[0154] (d1) laser-transparent intermediate layer;

[0155] (c) a laser-releasable layer comprising a laser-sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation-curable lacquers;

[0156] (d2) a laser-transparent intermediate layer; and

[0157] (b2) Laser-transmitting adhesive layer.

[0158] 25. The multilayer tape of any one of embodiments 1 to 24, comprising at least the following layer sequence:

[0159] (a1) an adhesive layer containing a foaming agent;

[0160] (b1) laser-transmitting adhesive layer;

[0161] (d1) laser-transparent intermediate layer;

[0162] (c) a laser-releasable layer comprising a laser-sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation-curable lacquers;

[0163] (b2) a laser-transmitting adhesive layer; and

[0164] (a2) Adhesive layer containing a foaming agent.

[0165] 26. The multilayer tape of any one of embodiments 1 to 26, comprising at least the following layer sequence:

[0166] (a1) an adhesive layer containing a foaming agent;

[0167] (b1) laser-transmitting adhesive layer;

[0168] (d1) laser-transparent intermediate layer;

[0169] (c) a laser-releasable layer comprising a laser-sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation-curable lacquers;

[0170] (d2) Middle layer

[0171] (b2) a laser-transmitting adhesive layer; and

[0172] (a2) Adhesive layer containing a foaming agent.

[0173] 27. A multilayer tape according to any one of embodiments 23 to 26, wherein the laser transparent intermediate layer according to (d1) and / or (d2) comprises a polymer, wherein the polymer is selected from polyethylene terephthalate (PET), polyethylene (PE), polyamide (PA) or polypropylene (PP), preferably polyethylene terephthalate (PET).

[0174] 28. The multilayer tape of any of embodiments 1 to 27, wherein the multilayer tape further comprises one or more release liners.

[0175] 29. A multilayer assembly comprising the multilayer tape according to any one of embodiments 1 to 28 and one or more adherends.

[0176] 30. The multi-layer assembly of embodiment 29, wherein the one or more adherends are laser transparent.

[0177] 31. A method for debonding a multilayer tape according to any one of embodiments 1 to 28, comprising

[0178] - subjecting the multilayer assembly according to embodiment 29 or 30 to a temperature in the range of 40 to 200° C. for a period in the range of 1 to 100 minutes; and / or

[0179] - subjecting the multilayer assembly according to embodiment 29 or 30 to laser light for a period of time ranging from 0.1 seconds to 10 minutes; and

[0180] - separating the multilayer tape from the one or more adherends.

[0181] 32. The method of embodiment 31, wherein the debonding comprises achieving expansion of the adhesive layer containing a blowing agent according to (a1) and / or (a2).

[0182] 33. The method of embodiment 31 or 32, wherein the debonding comprises subjecting the adhesive layer containing a blowing agent according to (a1) and / or (a2) to laser, heat or plasma.

[0183] 34. The method of embodiment 31, wherein the debonding comprises effecting oxidation and / or sublimation of the laser debondable layer according to (c).

[0184] 35. The method of embodiment 31, wherein the laser is an infrared laser, preferably, wherein the laser presents light having a wavelength in the range of 750 nm to 1400 nm.

[0185] 36. Use of the multilayer tape of any one of embodiments 1 to 28 in electronic devices, automotive devices, medical devices and dental devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0186] Figure 1 A multilayer tape (10) according to the present invention is shown, comprising the following layer sequence: an adhesive layer (121) containing a blowing agent; a laser-transmissive adhesive layer (131); a laser-debondable layer (14); and a laser-transmissive adhesive layer (132).

[0187] Figure 2 A multilayer assembly of a multilayer tape according to the present invention is shown, comprising the following sequence: adherent (111); adhesive layer (121) containing a foaming agent; laser-transparent adhesive layer (131); laser-debondable layer (14); laser-transparent adhesive layer (132); and adherent (112).

[0188] Figure 3 A method for debonding a multilayer tape (10) according to the invention is shown, comprising subjecting the multilayer assembly to a laser, thereby debonding the multilayer tape from an adherend at the surface of a laser debondable layer (14).

[0189] Figure 4 A method for debonding a multilayer tape (10) according to the invention is shown, comprising subjecting the multilayer assembly according to the invention to laser and / or heating, thereby debonding the multilayer tape from the adherend at the surface of the adhesive layer (121) containing a blowing agent.

[0190] Figure 5 A multilayer tape (10) according to the present invention is shown, which includes the following layer sequence: an adhesive layer (121) containing a blowing agent; a laser-transmissive adhesive layer (131); a laser-debondable layer (14); a laser-transmissive adhesive layer (132); and an adhesive layer (122) containing a blowing agent.

[0191] Figure 6 A multilayer assembly of a multilayer tape (10) according to the present invention is shown between two adherends (111) and (112), comprising the following sequence: adherend (111); adhesive layer (121) containing a foaming agent; laser-transparent adhesive layer (131); laser-debondable layer (14); laser-transparent adhesive layer (132); adhesive layer (122) containing a foaming agent and adherend (112).

[0192] Figure 7 A method for debonding a multilayer tape (10) according to the invention is shown, comprising subjecting the multilayer assembly to a laser, thereby debonding the multilayer tape from the adherend at the surface of the laser debondable layer (14).

[0193] Figure 8A method for debonding a multilayer tape (10) according to the present invention is shown, comprising subjecting the multilayer assembly according to the present invention to laser and / or heating, thereby debonding the multilayer tape from the adherend at the surface of the adhesive layers (121) and (122) containing a foaming agent, and debonding the multilayer tape from the adherend at the surface of the laser debondable layer (14).

[0194] Experimental Section

[0195] The present invention is further illustrated by the following examples.

[0196] Example:

[0197] The multilayer tape according to the present invention was subjected to (1) a debonding process at the laser debondable layer by laser activation for 10 seconds. After debonding at the laser debondable layer, for the pressure-sensitive adhesive composition (PSA, 75120, double-sided black tape consisting of highly shock-absorbing black acrylic foam) and a heat-activated adhesive composition (HAF, tesa 8474, a reactive heat-activated structural adhesive film based on phenolic resin and nitrile rubber, without backing and protected by a reinforcing paper liner), it was observed that the bond strength level in terms of push-out set-up dropped to 10-15% of the original strength. The multilayer tape according to the invention was then subjected to (2) an additional debonding process at the adhesive layer containing a blowing agent by one of the activation methods according to the invention (laser, thermal or plasma activation), wherein the substrates could be easily separated by hand, in particular for multilayer tapes comprising a heat-activated adhesive composition (HAF).

[0198]

[0199]

[0200] Reference Example: Rollout Test

[0201] The push-out test was carried out according to DE102016207550 A1. The multilayer tape according to the invention was placed on an inked glass. The die-cutting of the d / s tape was used to produce five test pieces by gluing a polycarbonate frame to a polycarbonate lens. If desired, additional substrate materials for the frame and the lens can be used.

[0202] The d / s tape is laminated to the liner. The outer diameter is 33 mm and the inner diameter is 29 mm (die cut area is 248 mm 2 ). The outer and inner squares were cut with a kiss cut. A perforated square with a length of 35 mm should be included to better position the sample into the template. The PC frame and lens were cleaned with ethanol and dried in a fume hood for at least two hours.

[0203] After 24 hours of storage in a climate chamber (23 ± 1 ° C, 50 ± 5% relative humidity), the maximum force and energy required to push the window out of a frame with a thickness of 3 mm by means of a punch are determined with a tensile tester. The maximum force in N and the energy in mJ are measured and expressed as the results "Push-out force" and "Push-out energy". The results of a single measurement are the maximum force, energy and detachment displayed by the tensile tester software. The final result is the average of five single results for the maximum force and debonding energy.

[0204] Prior Art Cited:

[0205] -C.Sato,in Recyicling and environmental aspects,2011,58, pages 1506-1526

[0206] -WO 2013 / 174650 A1

[0207] - WO 2010 / 245945 A1

[0208] -DE 102020209557 A1

[0209] -DE 102016207550 A1

Claims

1. A multilayer belt, comprising at least the following sequence of layers: (a1) an adhesive layer containing a foaming agent; (b1) laser-transmitting adhesive layer; (c) a laser releasable layer comprising a laser sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation curable lacquers; and (b2) Laser-transmitting adhesive layer.

2. The multilayer tape according to claim 1, comprising at least the following layer sequence: (a1) an adhesive layer containing a foaming agent; (b1) laser-transmitting adhesive layer; (c) a laser-releasable layer comprising a laser-sensitive material selected from the group consisting of metals, metal oxides, carbon black and radiation-curable lacquers; (b2) a laser-transmitting adhesive layer; and (a2) Adhesive layer containing a foaming agent.

3. The multilayer tape of claim 1 or 2, wherein the foaming agent-containing adhesive layer according to (a1) and / or (a2) comprises a polymer compound, preferably, wherein the polymer compound is selected from poly(meth)acrylates, polyurethanes, natural rubbers, synthetic rubbers and silicones, preferably poly(meth)acrylates and polyurethanes, more preferably poly(meth)acrylates.

4. The multilayer tape according to any one of claims 1 to 3, wherein the foaming agent-containing adhesive layer according to (a1) and / or (a2) comprises a foaming agent, preferably, wherein the foaming agent is selected from diazene compounds, preferably azodicarbonamide; hydrazine compounds, preferably p-toluenesulfonylhydrazide and 4,4'-oxybis(benzenesulfonylhydrazide); sulfonylsemicarbazide compounds, preferably p-toluenesulfonylsemicarbazide; tetrazole compounds, preferably 5-phenyl-1H-tetrazole; carbonate compounds, preferably sodium bicarbonate and zinc carbonate; and microspheres, preferably heat-expandable microspheres.

5. The multilayer tape of any one of claims 1 to 4, wherein the laser-transmissive adhesive layer according to (b1) and / or (b2) comprises a pressure-sensitive adhesive composition, preferably wherein the laser-transmissive adhesive layer according to (b1) and / or (b2) comprises at least 40 wt. % of poly(meth)acrylate, based on 100 wt. % of the pressure-sensitive adhesive composition.

6. The multilayer tape according to any one of claims 1 to 5, wherein the laser-transmissive adhesive layer according to (b1) and / or (b2) comprises a heat-activated adhesive composition.

7. The multilayer tape of claim 6, wherein the heat activated adhesive composition comprises 30 to 75 weight percent epoxy resin and 25 to 70 weight percent nitrile rubber, based on 100 weight percent of the heat activated adhesive composition.

8. The multilayer tape of claim 6, wherein the heat activated adhesive composition comprises 20 to 70 weight percent of the phenolic resin and 30 to 80 weight percent of the nitrile rubber, based on 100 weight percent of the heat activated adhesive composition.

9. The multilayer tape of any one of claims 1 to 8, wherein the laser sensitive material comprises a metal, preferably, wherein the metal is selected from the group consisting of Al, Cu, Ag, Au, Pt, Pd, Zn, Cr and Ti, preferably Al, Cu and Ti, more preferably Al.

10. The multilayer tape of any one of claims 1 to 8, wherein the laser sensitive material comprises a metal oxide, preferably, wherein the metal oxide is selected from silicon dioxide, titanium dioxide and tin zinc oxide, preferably titanium dioxide.

11. The multilayer tape of any one of claims 1 to 8, wherein the laser-sensitive material comprises carbon black.

12. The multilayer tape of any one of claims 1 to 8, wherein the laser sensitive material comprises a radiation curable lacquer, preferably wherein the radiation curable lacquer comprises a urethane acrylate.

13. The multilayer tape of any one of claims 1 to 12, wherein the laser-debondable layer according to (c) has a thickness in the range of 10 nm to 100 μm.

14. Multilayer assembly comprising a multilayer tape according to any one of claims 1 to 13 and one or more adherends.

15. A method for debonding a multilayer tape according to any one of claims 1 to 13, the method comprising - subjecting the multilayer assembly according to claim 14 to a temperature in the range of 40 to 200° C. for a period in the range of 1 to 100 minutes; and / or - subjecting the multilayer assembly according to claim 14 to laser light for a period of time in the range from 0.1 seconds to 10 minutes; and - Separating the multilayer tape from the one or more adherends.

16. Use of the multilayer tape according to any one of claims 1 to 13 in electronic devices, automotive devices, medical devices and dental devices.

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