Curable compound which can be removed using moisture

Abstract

The invention relates to a curable compound which can be removed using moisture, the compound comprising the following components: (A) a tertiary epoxide; (B) a vinyl ether; and (C) a latent acidifier for the cationic polymerisation. Component (A) and / or component (B) comprise at least one at least difunctional compound. Component (B) is present in a proportion of at least 25 wt.%, based on the total weight of the compound; and components (B) and (A) are present in the compound in a ratio of at least 1.5:1, based on the proportion by weight of the particular component relative to the total weight of the compound. The invention also relates to the use of such a compound and to a method for gluing, coating or casting.

Description

[0001] DELO Industrial Adhesives GmbH & Co. KGaA

[0002] Our reference number: D 3393 WO

[0003] Hardenable and moisture-removable mass

[0004] AREA OF INVENTION

[0005] The invention relates to a mass based on epoxies and vinyl ethers that can be cured by actinic radiation and / or heat and is removable with moisture. The invention further relates to the use of such a mass for producing a removable bond, a removable coating, or a removable potting compound, as well as a method for bonding, coating, or potting.

[0006] TECHNICAL BACKGROUND

[0007] The delamination or dissolution of cured adhesives can be caused by various physical or chemical signals. For example, bonds can be chemically dissolved by solvents, acids, or bases. This is detrimental both in terms of the components themselves and from environmental and occupational safety perspectives.

[0008] From US patent 6,288,170 B1, epoxy formulations are known that, in addition to a hardener, contain thermally expandable microspheres. These microspheres release gases at elevated temperatures, thus allowing the bond to separate. A disadvantage is the need for high filler concentrations to achieve a high degree of removability. At the same time, the microspheres exhibit low shear stability, which negatively affects the processability of such compounds.

[0009] Formulations with epoxy resins containing acetal bonds are known, for example, from US 5,932,682 A. These formulations contain anhydrides as hardeners and are intended for encapsulating electronic components. Mixtures of acetal-containing epoxides with an acetal-free cycloaliphatic epoxy show only a moderate reduction in the glass transition temperature after one week of temperature and humidity storage, without dissolving. Post-processing of components can therefore only be carried out with considerable time and energy expenditure. US 2017 O 298 163 A1 discloses formulations with acetal-functional crosslinkers containing (meth)acrylate groups. Only linearly structured crosslinkers are described. The formulations generally have a glass transition temperature of less than 50 °C and are intended for use as pressure-sensitive adhesives.The use of only difunctional (meth)acrylates based on acetals prevents the formulation of materials with high stability and / or glass transition temperatures. Therefore, this pressure-sensitive polymer is unsuitable for processes in the semiconductor industry.

[0010] EP 2 169 018 A2 describes an ink formulation for inkjet printing which, in addition to a cationically polymerizable component and a photolatent acid, also contains a pigment. Vinyl ethers and / or oxetanes are proposed as the cationically polymerizable component, wherein, in particular, 65 to 100 wt% of the cationically polymerizable component consists of one or more compounds with a viscosity of no more than 12 mPa s at 25 °C, based on the total weight of the cationically polymerizable component, in order to ensure the lowest possible viscosity of the ink formulation and thus facilitate metering during inkjet printing. The resolubility of the cured masses under aqueous conditions is not described.

[0011] US Patent 2006 O 264 529 A1 discloses cationically radiation-curable compositions that necessarily contain at least one alpha-, beta-substituted epoxy. Furthermore, the compositions may contain other polymerizable components such as oxetanes and / or vinyl ethers. The compositions are intended to possess advantageous resistance to various media as well as to temperature and humidity. The preferred use is as a radiation-curable ink.

[0012] From DE 10 2020 118 813 A1, resoluble masses based on polyacetals are known, which can carry various functional groups such as epoxides, oxetanes, or (meth)acrylates. The described raw materials have a controllable acetal density and allow for deposition and / or dissolution in, for example, 80 °C warm water within a few minutes to an hour. The synthesis of the functionalized polyacetals is complex and costly.

[0013] A disadvantage of the resoluble compositions described in the prior art is that they either require harsh conditions and / or longer periods of time for resolution, cannot be removed without leaving residues, or contain high proportions of compounds that do not polymerize into the network of the composition.

[0014] SUMMARY OF THE INVENTION

[0015] The invention is based on the objective of avoiding the disadvantages of compositions known from the prior art and of providing curable compositions that can be removed again with moisture after curing at low temperatures.

[0016] Furthermore, the compositions according to the invention are said to form a high-strength and reliable polymeric network after curing in the absence of moisture.

[0017] These problems are solved according to the invention by a hardenable and moisture-removable mass according to claim 1.

[0018] Advantageous embodiments of the mass according to the invention are specified in the dependent claims, which can optionally be combined with one another.

[0019] The mass includes at least the following components:

[0020] (A) a tertiary epoxide,

[0021] (B) a vinyl ether, and

[0022] (C) a latent acid former for cationic polymerization, wherein component (A) and / or component (B) comprises at least one at least difunctional compound, wherein component (B) is present in a proportion of at least 25 wt%, based on the total mass, and wherein components (B) and (A) are present in a ratio of at least 1.5:1 in the mass, based on the weight fraction of each component in the total mass.

[0023] The term "at least difunctional" means that two or more of the respective functional groups are present in the compound. Accordingly, an at least difunctional epoxide has two or more epoxide groups, and an at least difunctional vinyl ether has two or more vinyl ether groups.

[0024] The compositions according to the invention are particularly suitable for temporary joining applications.

[0025] The curable composition according to the invention is liquid at room temperature and can be cured by various curing mechanisms such as actinic radiation and / or heat.

[0026] The objects of the invention are further achieved by using the previously described mass to produce a releasable bond, a releasable coating or a releasable potting compound.

[0027] Furthermore, the objects of the invention are solved by a method for bonding, coating, or casting a substrate using the previously described compound, wherein the method comprises the following steps: The compound is metered onto the substrate. Optionally, a second substrate is added to form a substrate composite, and the second substrate is brought into contact with the compound. Subsequently, the compound is cured by irradiation with actinic radiation and / or heat curing to obtain a cured compound. The cured compound obtained by the method according to the invention can then be removed from the substrate or from the substrate composite, if necessary, by exposure to moisture.

[0028] DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS

[0029] The invention is described in detail and by way of example below with reference to preferred embodiments, which, however, should not be understood in a limiting sense. “Tertiary epoxide” means that at least one epoxide group of the corresponding compound contains a carbon atom which is bonded to three further carbon atoms.

[0030] For the purposes of this invention, "liquid" means that at room temperature, the loss modulus G" determined by viscosity measurement is greater than the storage modulus G' of the mass in question. Room temperature is defined as 23 ± 2 °C.

[0031] The compositions are considered removable if, after hardening, they detach from a substrate under the influence of moisture and, optionally, temperature. The moisture can be introduced to the hardened mass in the form of steam and / or water to facilitate detachment.

[0032] Insofar as the indefinite article “ein” or “eine” is used, this also includes the plural form “ein oder mehr”, unless this is expressly excluded.

[0033] “Mixed functional” means that each molecule contains at least two different functional groups.

[0034] All weight percentages listed below refer to the total weight of the mass, unless otherwise stated.

[0035] Component (A): Tertiary epoxy

[0036] The curable mass according to the invention contains at least one tertiary epoxide as a cationically polymerizable component (A).

[0037] The tertiary epoxide is not structurally restricted and can have an aliphatic, cycloaliphatic, and / or aromatic backbone. Crucially, the compound of component (A) must exhibit a tertiary substitution pattern as defined above.

[0038] The use of the tertiary epoxy enables or at least promotes copolymerization between the cationically polymerizable component (A) and the vinyl ether of component (B) during the curing of the mass, allowing a network to form in which a sufficient number of acetal functionalities are formed through the reaction of epoxy and vinyl ether groups. These functionalities can be cleaved again under the influence of moisture, thus enabling the cured mass to be removed again under the influence of moisture.

[0039] Without adhering to a specific scientific theory, the particularly advantageous effect of tertiary epoxides in the construction of such networks is attributed to their ability to rearrange to particularly stable carbocations. This positively influences the reactivity during the construction of a mixed network consisting of repeating units derived from the cationically polymerizable component (A) and repeating units derived from the vinyl ether of component (B). In particular, tertiary epoxides exhibit a lower tendency toward homopolymerization than primary or secondary epoxides, thus allowing the desired cross-polymerization to predominate in the reaction of the tertiary epoxides. This, in turn, enables the increased formation of acetal functionalities that can be cleaved by moisture.

[0040] Components (B) and (A) are present in the mass in a ratio of at least 1.5:1, based on the weight fraction of the respective component in the total weight of the mass. In other words, the mass according to the invention has, in particular, an excess of vinyl ether compared to the tertiary epoxide. In this way, the yield of acetal functionalities formed in the polymer network of the cured mass can be further increased, since the homopolymerization of the tertiary epoxide (A1) can be suppressed even further by the excess of vinyl ether.

[0041] In one variant, components (B) and (A) are present in a ratio of at least 2:1 in the mass, based on the weight fraction of the respective component to the total weight of the mass.

[0042] The ratio of components (B) and (A), based on the weight fraction of the respective component to the total weight of the mass, can be in a range of 1.5:1 to 10:1, preferably in a range of 2:1 to 5:1, particularly preferably in a range of 2:1 to 3:1.

[0043] Exemplary tertiary epoxides that can be used in the composition according to the invention are described in US 2006 / 0264529 A1. The tertiary epoxide can be monofunctional or at least difunctional. If only monofunctional tertiary epoxides are used in the component, at least one vinyl ether of component (B) is at least difunctional.

[0044] The tertiary epoxide can be selected from the group consisting of limonene dioxide (LDO), limonene-1,2-epoxide (LMO), alpha-pinene oxide, and mixtures thereof, preferably from the group consisting of limonene dioxide (LDO), limonene-1,2-epoxide (LMO), and mixtures thereof. These tertiary epoxides exhibit excellent reactivity with vinyl ethers and are commercially available.

[0045] Component (A) is present in the mass according to the invention in a proportion of at least 5 wt.%, preferably at least 15 wt.%, particularly preferably at least 30 wt.%, in each case based on the total weight of the mass.

[0046] For example, the mass according to the invention comprises 5 to 40 wt.% of component (A), preferably 10 to 40 wt.%, particularly preferably 12 to 38 wt.%, in each case based on the total weight of the mass.

[0047] Component (B): Vinyl ether

[0048] In addition to component (A), the mass according to the invention contains at least one vinyl ether as component (B), wherein component (B) is present in a proportion of at least 25 wt.%, based on the total weight of the mass.

[0049] Upon cationic polymerization, vinyl ethers generate a carbocation in which the positively charged carbon atom is directly bonded to an oxygen atom. The reaction of this carbocation with the tertiary epoxide of component (A) converts the carbocation into an acetal. The tertiary epoxide of component (A), through the formation of a stabilized carbocation, allows the transfer reaction to the vinyl ether. This transfer reaction enables further reactions of epoxides of component (A) with the propagating carbocation of the vinyl ether, forming a cleavable acetal group. In other words, the hardening of the composition according to the invention occurs, in particular, through a cationic copolymerization of the cationically polymerizable component (A) and the vinyl ether of component (B).This does not preclude the possibility that at least some homopolymers may also form in the hardened mass, based solely on the vinyl ether or solely on the tertiary epoxy.

[0050] The minimum proportion of component (B) of 25 wt%, based on the total weight of the mass, ensures that the desired cross-reaction between the vinyl ether and the tertiary epoxy occurs to an extent that allows for the resolubility of the cured mass. In other words, the minimum proportion of component (B) ensures that a sufficient amount of acetal functionalities is present in the polymer network of the cured mass to guarantee resolubility by moisture.

[0051] Preferably, component (B) comprises or includes at least one at least difunctional vinyl ether. In this case, the tertiary epoxy may also be monofunctional, while still ensuring satisfactory curing of the mass with sufficient mechanical properties.

[0052] However, this does not preclude the possibility that the tertiary epoxide (A1) may also be at least difunctional, particularly to further increase the cross-linking within the polymer network.

[0053] Suitable vinyl ethers include trimethylolpropane trivinyl ether, ethylene glycol divinyl ether, triethylene glycol divinyl ether (DVE-3), 1,4-butanediol divinyl ether (BDDVE), 1,4-cyclohexanedimethanol divinyl ether (CHDM-di), 1,2,3-Tris(vinyloxy)propane, 1,3,5-Tris[(2-vinyloxy)ethoxy]benzene, Tris[4-(vinyloxy)butyl] 1,2,4-benzenetricarboxylate, 1,3,5-Tris(2-vinyloxyethyl)-1,3,5-triazin, 1,3,5-cyclohexantrimethanol trivinyl ether, 1,1,1-Tris-4-[2-(vinyloxy)ethoxy]phenylethane, tetrakis(vinyloxymethyl)methane and cyclic vinyl ethers as well as mixtures thereof.

[0054] Furthermore, vinyl ethers of polyfunctional alcohols can be used.

[0055] The component (B) can be present in the mass according to the invention in a proportion of 25 to 90 wt.%, preferably 30 to 80 wt.%, particularly preferably 45 to 70 wt.%, in each case based on the total weight of the mass.

[0056] Component (C): Latent acidifier

[0057] The mass according to the invention contains, in addition to components (A) and (B), at least one latent acid former for cationic polymerization.

[0058] The latent acidifier serves as an initiator for the cationic polymerization of components (A) and (B) of the mass according to the invention.

[0059] The choice of the latent acidifier is specifically tailored to the tertiary epoxide of component (A) and the vinyl ether of component (B) used, so that the acid released by the latent acidifier after activation generates carbocations of the tertiary epoxide and / or the vinyl ether to the desired extent.

[0060] The latent acid-forming agent of component (C) can comprise a photolatent acid (C1) and / or a thermally latent acid-forming agent (C2). Thus, the latent acid-forming agent (C) can be activated by actinic radiation and / or heat.

[0061] The latent acid-forming agent includes, for example, metallocenium-based initiators and / or onium compounds. An overview of various metallocenium salts is disclosed in EP 0 542 716 B1. Examples of different anions of the metallocenium salts include HSO₄⁻, PFe⁻, SbF₆⁻, ASF₆⁻, Cl⁻, Br⁻, CIO₄⁻; PO₄SO₃CF₃⁻; OT⁻ (tosylate), aluminates, and borate anions, such as BF₄⁻ and B(C₆F₅)₄⁻.

[0062] Preferred photolatent acids (C1) based on a metallocenium compound are selected from the group of ferrocenium salts.

[0063] Preferred photolatent acids (C1) based on onium compounds are selected from the group of arylsulfonium salts, aryliodonium salts and combinations thereof and are described in the prior art.

[0064] Commercially available photolatent acids (C1) based on triarylsulfonium are marketed under the brand names Chivacure 1176, Chivacure 1190 from Chitech, Irgacure 290, Irgacure 270, Irgacure GSID 26-1 from BASF, Speedcure 976 and Speedcure 992 from Lambson, TTA UV-692, TTA UV-694 from Jiangsu Tetra New Material Technology Co., Ltd. or UVI-6976 and UVI-6974 from Dow Chemical Co.

[0065] Commercially available photolatent acids (C1) based on diaryliodonium include, among others, the brand names LIV1240, LIV1242 or LIV2257 from Deuteron and Bluesil 2074 from Bluestar.

[0066] The photolatent acids (C1) used in the mass according to the invention are preferably activatable by irradiation with actinic radiation of a wavelength in the range of 200 to 480 nm.

[0067] If necessary, the photolatent acid (C1) can be combined with a suitable sensitizing agent as an additive.

[0068] Additionally or instead of the photolatent acid (C1), the mass according to the invention can also contain a thermally latent acid former (C2) for cationic polymerization.

[0069] Suitable thermally latent acidifiers (C2) include, for example, quaternary N-benzylpyridinium salts and N-benzylammonium salts, as disclosed in EP 0 343 690 A2 or WO 2005 / 097 883 A2. Thermally latent sulfonium salts, as described in WO 2019 / 043 778 A1, can also be used as acidifiers (C2).

[0070] Commercially available products are available under the names K-PLIRE CXC-1614, K-PURE CXC-1733 or K-PURE CXC-1821 from King Industries Inc. and SAN-AID SI-80L and SAN-AID SI-100L from SAN-SHIN Chemical Industry Co. Ltd.

[0071] In addition, various metal chelate complexes based on titanium or aluminum can be used as thermally latent acid formers (C2).

[0072] The mixture of one or more acid-forming agents is also in accordance with the invention. For example, in addition to the photolatent acid-forming agent (C1), a thermally latent acid-forming agent (C2) can be present. The corresponding compositions are dual-curing.

[0073] The latent acidifier can be contained in the mass according to the invention in a total proportion of 0.001 to 5 wt.%, preferably 0.01 to 3 wt.%, particularly preferably 0.1 to 2 wt.%, in each case based on the total weight of the mass.

[0074] Component (D): Further cationically polymerizable component

[0075] In addition to the tertiary epoxide of component (A), the curable mass according to the invention can contain a further cationically polymerizable component (D) comprising at least one compound selected from the group consisting of epoxides (D1) and oxetanes (D2), wherein, in the case that component (D) contains an epoxide, this epoxide is not a tertiary epoxide and thus differs from the tertiary epoxide of component (A). The further cationically polymerizable component (D) consists in particular of at least one compound selected from the group consisting of epoxides (D1) and oxetanes (D2).

[0076] Suitable epoxides (D1) are, for example, difunctional cycloaliphatic epoxy resins and include compounds that bear both a cycloaliphatic group and at least two oxirane rings. Examples include 3-cyclohexenylmethyl-3-cyclohexylcarboxylate diepoxide, 3,4-epoxycyclohexylalkyl-3',4'-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3',4'-epoxy-6-methylcyclohexanecarboxylate, vinylcyclohexene dioxide, bis(3,4-epoxycyclohexylmethyl)adipate, dicyclopentadiene dioxide, and 1,2-epoxy-6-(2,3-epoxypropoxy)hexahydro-4,7-methanindane, as well as mixtures thereof.

[0077] Aromatic epoxy resins can also be used in the compositions according to the invention as the epoxy (D1) in the further cationically polymerizable component (D). Examples of aromatic epoxy resins are bisphenol-A epoxy resins, bisphenol-F epoxy resins, phenol-novolac epoxy resins, cresol-novolac epoxy resins, biphenyl epoxy resins, 4,4'-biphenyl epoxy resins, divinylbenzene dioxide, 2-glycidylphenyl glycidyl ethers, naphthalenediol diglycidyl ethers, glycidyl ethers of tris(hydroxyphenyl)methane and glycidyl ethers of tris(hydroxyphenyl)ethane, as well as mixtures thereof. Furthermore, all fully or partially hydrogenated analogues of aromatic epoxy resins can also be used.

[0078] Isocyanurates and other heterocyclic compounds substituted with epoxide-containing groups can also be used as the epoxide (D1) in the composition according to the invention. Triglycidyl isocyanurate and monoallyldiglycidyl isocyanurate are examples.

[0079] Furthermore, polyfunctional epoxy resins of all the resin groups mentioned, epoxy-functionalized prepolymers based on oligo- and polymer diols, tough elasticized epoxy resins and mixtures of different epoxy resins can also be used as epoxy (D1) in the mass according to the invention.

[0080] Also in accordance with the invention is a combination of several epoxy-containing compounds, at least one of which is di- or higher-functional, in component (D).

[0081] In addition to at least difunctional epoxide-containing compounds, monofunctional epoxides can also be used as reactive diluents as epoxide (D1).

[0082] The epoxy (D1) can be present in a proportion of 0 to 30 wt.%, preferably in a proportion of 0 to 20 wt.%, particularly preferably in a proportion of 0 to 15 wt.%, in each case based on the total weight of the mass.

[0083] Instead of or in addition to the epoxide (D1), preferably at least difunctional oxetanes (D2) can be used in the further cationically polymerizable component (D) of the mass according to the invention. Processes for the preparation of oxetanes are known in particular from US 2017 / 0198093 A1.

[0084] Examples of commercially available and suitable oxetanes (D2) are bis(1-ethyl-3-oxetanyl-methyl) ether (DOX), 3-allyloxymethyl-3-ethyloxetane (AQX), 3-ethyl-3-[(phenoxy)-methyloxetane (POX), 3-ethyl-3-hydroxymethyl-oxetane (OXA), 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene (XDO), and 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane (EHOX). These oxetanes are commercially available from TOAGOSEI CO., LTD. The oxetane (D2) may be present in a proportion of 0 to 30 wt.%, preferably in a proportion of 0 to 20 wt.%, and particularly preferably in a proportion of 0 to 30 wt.%, in each case based on the total mass.

[0085] The epoxy (D1) and the oxetane (D2) of component (D) are present in a total proportion of no more than 50 wt.%, based on the total weight of the mass.

[0086] Component (E): Chain carrier

[0087] The mass according to the invention can contain as component (E) a chain carrier selected from the group of polyols.

[0088] Polyols are compounds with at least two hydroxyl groups and are particularly suitable as chain carriers in the mass according to the invention.

[0089] The chain carrier can contribute to making the mass more flexible, which can have a beneficial effect on the release properties of the hardened mass.

[0090] Suitable polyols are available, for example, based on polyethers, polyesters, polycaprolactones, polycarbonates, polybutadienediols or hydrogenated polybutadienediols.

[0091] In particular, higher molecular weight polyols can also be used to make cationic masses more flexible. Examples of commercially available higher molecular weight polyols include products marketed under the trade names ETERNACOLL UM-90 (1 / 1), Eternacoll UHC50-200 from UBE Industries Ltd., Capa™ 2200, Capa™ 3091 from Perstorp, Liquiflex H from Petroflex, Merginol 901 from HOBIIM Oleochemicals, Placcel 305, Placcel CD 205 PL from Daicel Corporation, Priplast 3172, Priplast 3196 from Croda, Kuraray Polyol F-3010, Kuraray Polyol P-6010 from Kuraray Co., Ltd., Krasol LBH-2000, Krasol HLBH-P3000 from Cray Valley, or Hoopol S-1015-35 or Hoopol S-1063-35 from Synthesia. Internacional SLU are available.

[0092] Component (E) may be present in a proportion of at most 50 wt.%, preferably in a proportion of at most 40 wt.%, and particularly preferably in a proportion of at most 20 wt.%, in each case based on the total weight of the mass. Component (F): Filler

[0093] The composition according to the invention can optionally contain a filler. This influences the chemical resistance, media absorption, and coefficient of thermal expansion of the composition according to the invention. Depending on the required property profile and intended use of the composition according to the invention, various fillers or combinations thereof can be used.

[0094] To achieve a low coefficient of thermal expansion, quartz or quartz glass is typically used as a filler. Materials with negative coefficients of thermal expansion, such as zirconium tungstate, can also be used for this purpose.

[0095] To achieve higher thermal conductivity, fillers such as aluminum oxides, aluminum nitride, boron nitride, graphite (including expanded graphite or graphite-based nanotechnology products), carbon nanotubes, or metallic fillers can be used.

[0096] To achieve isotropic or anisotropic electrical conductivity, metallic fillers or non-metallic fillers coated with electrically conductive layers can be used.

[0097] To achieve defined adhesive layer thicknesses, so-called "spacer particles" with narrowly defined particle shapes and particle size distributions can be used as fillers.

[0098] The selection of fillers is in no way limited with regard to particle shapes (such as angular, spherical, plate-shaped, needle-shaped, or hollow forms) and particle sizes (macroscopic, microscopic, nanoscale). It is also well known that different particle shapes or sizes, or particle size distributions, can be used in combination to achieve, for example, low viscosity, a higher maximum filler density, or high electrical and thermal conductivity.

[0099] Preferably, the filler is selected from the following group: oxides, nitrides, borides, carbides, sulfides and silicides of metals and semimetals, including mixed compounds of several metals and / or semimetals; carbon modifications such as diamond, graphite and carbon nanotubes; silicates and borates of metals and semimetals; all types of glasses; metals and semimetals in elemental form, in the form of alloys or intermetallic phases; inorganic or organic salts insoluble in the resin matrix; particles of polymeric materials, such as silicone, polyamide, polyethylene and PTFE; and combinations thereof.

[0100] The use of mixtures of different fillers is also within the scope of this invention.

[0101] The component (F) can be present in the mass according to the invention in a proportion of 0 to 70 wt.%, preferably 10 to 70 wt.%, particularly preferably 20 to 60 wt.%, in each case based on the total weight of the mass.

[0102] Component (G): Additives

[0103] The mass according to the invention can also optionally

[0104] Components are included as additives.

[0105] The additives are preferably from the group of dyes, pigments,

[0106] Anti-aging agents, fluorescent agents, stabilizers,

[0107] Polymerization accelerators, sensitizing agents, adhesion promoters,

[0108] Desiccants, crosslinking agents, flow improvers, wetting agents,

[0109] Thixotropic agents, reactive and non-reactive diluents,

[0110] Flexibilizer, polymeric thickener, flame retardant,

[0111] Corrosion inhibitors, plasticizers, tackifiers and combinations thereof were selected.

[0112] The preceding list of additives should be considered exemplary and in no way limiting.

[0113] The component (G) can be present in the mass according to the invention in a proportion of 0 to 40 wt.%, preferably 1 to 25 wt.%, particularly preferably 2 to 15 wt.%, in each case based on the total weight of the mass. Formulation of the mass according to the invention

[0114] One formulation of the composition according to the invention comprises at least the components (A) to (C). Furthermore, it may contain the additional cationically polymerizable component (D), chain carriers (E), fillers (F) and / or additives (G).

[0115] In one embodiment, the mass comprises or consists of the following components, each in relation to the total weight of the mass:

[0116] (A) 5 to 40 wt% of the tertiary epoxide;

[0117] (B) 25 to 90 wt.% of the vinyl ether;

[0118] (C) 0.001 to 5 wt% of the latent acidifier;

[0119] (D) 0 to 50 wt.% of the other cationically polymerizable component;

[0120] (E) 0 to 50 wt.% of the chain carrier;

[0121] (F) 0 to 70 wt.% of the filler;

[0122] (G) 0 to 40 wt.% of the additive, in particular from the group of dyes,

[0123] Pigments, antioxidants, fluorescent agents, stabilizers,

[0124] Polymerization accelerator, SI sensitizing agent, adhesion promoter,

[0125] Desiccants, crosslinking agents, flow improvers, wetting agents,

[0126] Thixotropic agents, reactive and non-reactive diluents,

[0127] Flexibilizer, polymeric thickener, flame retardant,

[0128] Corrosion inhibitors, plasticizers, tackifiers and combinations thereof.

[0129] In particular, the aforementioned proportions add up to 100 wt.%, so that the mass consists of the aforementioned components.

[0130] The composition according to the invention is preferably provided as a single-component composition. "Single-component" means that all components of the composition are present together in a single packaging unit.

[0131] Use of the mass according to the invention

[0132] The composition according to the invention is particularly suitable for creating releasable bonds, coatings, and potting compounds. These can, for example, be applied to expensive components as a protective layer during the production process and subsequently removed under mild conditions. Its use as a joining solution for electronic applications in conjunction with end-of-life recycling of the devices, including component recovery, is also conceivable.

[0133] This compound has the advantage over comparable materials from the prior art that, under mild conditions, it can be removed from the component essentially without residue, preferably completely without residue. At the same time, the hardened compound is characterized by reliable mechanical properties, as long as it is not subjected to the removal conditions.

[0134] To remove the bond, coating or potting from the cured mass, the bond, coating or potting can be exposed to moisture for a predetermined time and at a predetermined temperature after the mass has cured, so that the cured mass is at least partially, and preferably completely, detached from a substrate on which the mass was previously cured.

[0135] If the hardened mass bonds the substrate to a second substrate, the hardened mass is at least partially, and in particular completely, detached from the second substrate at the same time.

[0136] Moisture can be added to the hardened mass in the form of steam and / or water.

[0137] The predetermined temperature is chosen to be as low as possible to minimize the energy costs of the removal process. This also minimizes the thermal stress on the components from which the material is being removed. The predetermined temperature can range from 20 to 100 °C.

[0138] The predetermined time depends on various factors, such as the type of hardened material, the acetal density in the hardened material, the quantity of hardened material, the layer thickness of the hardened material, the accessibility of the hardened material, and the type of applied moisture. Preferably, the predetermined time is chosen to be as short as possible to increase process efficiency and can range from a few minutes to a maximum of three hours.

[0139] The removal process can be accelerated in particular by using moisture in the form of an aqueous solution with a pH value of less than 7.

[0140] Furthermore, the hardened mass achieves high levels of adhesion; for example, a compressive shear strength of at least 3 MPa is achieved on the substrate combination glass / glass, preferably at least 5 MPa, and more preferably at least 10 MPa.

[0141] Hardening of the masses according to the invention

[0142] The masses according to the invention can be hardened either thermally and / or by actinic radiation, in particular UV radiation.

[0143] Measurement methods, devices and definitions used

[0144] The following explains the measurement methods and definitions used in connection with the masses and tests presented in Tables 1 and 2.

[0145] Radiation

[0146] For irradiation, the masses according to the invention were treated with LED lamps of the DELOLUX series from DELO Industrie Klebstoffe GmbH & Co. KGaA with a wavelength of 365 nm at an intensity of 200 ± 20 mW / cm². 2 irradiated.

[0147] Curing

[0148] "Crosslinking" or "curing" are defined as polymerization or addition reactions beyond the gel point. The gel point is the point at which the storage modulus G' equals the loss modulus G".

[0149] room temperature

[0150] Room temperature is defined as 23 ± 2 °C.

[0151] Testing the detachment properties of the masses

[0152] To test the removability of the masses according to the invention, two test specimens (dimensions 20 mm * 20 mm * 5 mm each) made of glass with a square cross-section were bonded horizontally to each other using the respective mass, with one of the test specimens being rotated by 45° relative to the other test specimen and the centers of both test specimens being arranged one above the other.

[0153] For this purpose, a 10 mg drop of the respective compound was applied to the center of the largest surface of the first test specimen, and the second test specimen was attached parallel to it, rotated horizontally by 45°. The adhesive layer thickness of 0.1 mm was adjusted using spacer wires.

[0154] The joined samples were irradiated for 10 seconds and conditioned at room temperature for 24 hours before testing. For the mass according to Example 11, heat curing in a preheated convection oven at 100 °C for 30 minutes followed light curing.

[0155] The test specimens were then placed in an 80 °C water bath (pH 4) and the time until the bond ruptured was measured. Five samples were tested in each case, and the mean value was calculated. If no delamination was observed within 3 hours, "nb" was noted.

[0156] compressive shear strength (DSF)

[0157] Two glass specimens (dimensions 20 mm × 20 mm × 5 mm) with a square cross-section were bonded together with a 5 mm overlap using the respective adhesive. A bead of the adhesive was applied to the first specimen, and then a second specimen was joined. The adhesive layer thickness of 0.1 mm and the overlap were adjusted using spacers and / or a bonding device. The joined specimens were irradiated for 10 seconds and conditioned at room temperature for 24 hours before testing. For the adhesive used in Example 11, heat curing was performed in a preheated convection oven at 100 °C for 30 minutes following light curing.

[0158] Production of the hardenable masses

[0159] First, all liquid components were mixed, and then any fillers and optionally further solids were incorporated using a laboratory stirrer, laboratory dissolver, or a speed mixer (Hauschild) until a homogeneous mass was obtained. Masses containing photoinitiators and sensitive to visible light must be prepared under light outside the excitation wavelength of the photoinitiators or sensitizers.

[0160] The masses produced in this way were filled into single-chamber cartridges and sealed.

[0161] The following list contains all the compounds used in the examples for the production of the hardenable masses and their abbreviations:

[0162] Examples of wording:

[0163] Component (A): Tertiary epoxy

[0164] (A.1) Limonene dioxide (LDO) available from Nitrochemie Aschau GmbH

[0165] (A.2) Limonene-1,2-epoxide (LMO), available from Sigma Aldrich

[0166] Component (B): Vinyl ether

[0167] (B.1) Triethylene glycol divinyl ether (DVE-3), available from BASF SE

[0168] (B.2) Butanediol divinyl ether, available from BASF SE

[0169] (B.3) Vinyl ether prepolymer

[0170] Manufacturing Component (B.3):

[0171] In a heated vessel, 150.0 g (0.74 mol) of triethylene glycol divinyl ether (B.1); 89.35 g (0.66 mol) of dipropylene glycol; 3.69 g (27 mmol, 1 eq.) of 1,1,1-tris(hydroxymethyl)propane; and 0.47 g (0.005 mmol) of oxalic acid were placed. The reaction mixture was then heated at 80 °C for 23 h with continuous stirring. 220 g (90%) of an acetal-functional vinyl ether prepolymer (B.3) with a viscosity of 65,030 mPas were obtained.

[0172] Component (C): Latent acidifier

[0173] (C.1) Chivacure 1176 = Diphenyl(4-phenylthio)phenylsulfonium hexafluoroantimonate and (Thiodi-4,1-phenylene)bis(diphenylsulfonium) dihexafluoroantimonate, 50% in propylene carbonate, available from Chitec (photoinitiator)

[0174] (C.2) K-Pure CXC-1733 = quaternary benzylammonium salt, 50% w / w in propylene carbonate, available from King Industries (heat-latent acidifier)

[0175] Further cationically polymerizable component (D)

[0176] (D1.1) Celloxide 2021 P = 3,4-Epoxycyclohexylmethyl-3',4'- epoxycyclohexanecarboxylate, available from Daicel

[0177] (D1.2) jER YL 980 = Bisphenol-A epoxy resin, available from Mitsubishi Chemical

[0178] (D2.1) OXT221 = Bis[1-Ethyl(3-oxetanyl)]methyl ether, available from Toagosei

[0179] Component (E): Chain transfer unit

[0180] (E.1) Kuraray Polyol P-1021, available from Kuraray Europe GmbH

[0181] Component (F): Filler

[0182] (F.1) Fused Silica FB-3SDC, available from Denki Kagaku Kögyö KK;

[0183] (F.2) Ulmer Weiß XMF, available from Merkle Eduard GmbH & Co.

[0184] Component (G): Additives

[0185] (G.1) Cab-O-Sil TS-720, available from Cabot Corporation (thixotropic agent)

[0186] Table 1: Overview of examples according to the invention.

[0187]

[0188] Table 2: Overview comparison examples.

[0189]

[0190] Examples 1 to 12 comprise masses according to the invention. Examples 13 to 16, on the other hand, represent comparative examples.

[0191] Example 1 has a ratio of vinyl ether (B.1) to tertiary epoxy (A1) of 2:1. The formulation is light-curable due to the photolatent acid former. The cured mass achieves a strength of 26 MPa in a glass / glass bond. Nevertheless, detachment is possible under the described conditions within approximately one hour.

[0192] By varying the ratios of vinyl ether to tertiary epoxy, the time until detachment can be further reduced. For example, Example 2 (ratio (B.1) to (A.1) = 8 : 1) is already re-soluble within 11 minutes.

[0193] Example 3 shows a variation of the ratio of components (B) and (A), where the ratio (B.1):(A.1) is 1.5 : 1. A strength of 26 MPa is still achieved with a detachment time of still slightly less than one hour.

[0194] As shown in Example 6, varying the tertiary epoxide also provides a way to shorten the time until detachment.

[0195] Examples 4 and 5 demonstrate the suitability of various vinyl ethers or mixtures of vinyl ethers for producing the mass according to the invention. Example 5 also uses a prepolymer vinyl ether (component (B.3)). This can also be advantageously used in the mass as component (B).

[0196] The addition of further cationically polymerizable components such as cycloaliphatic epoxides (Example 8), aromatic epoxides (Example 9), or oxetanes (Example 11) is also possible without the masses losing their resolubility. At the same time, the achievable strengths remain at a high level.

[0197] Chain carriers such as polyols are also tolerated in the composition according to the invention, as shown in Example 10. The hardened composition allows the joining of a joint to be loosened within 85 minutes.

[0198] Comparison examples 13 and 15 do not contain tertiary epoxy. The cured mass in comparison example 13 cannot be removed within 3 hours. Comparison example 15, due to its high vinyl ether content of 94.5 wt%, results in a non-curable mass.

[0199] Comparative example 14 shows a ratio of vinyl ether (B.1) to tertiary epoxy of 1:1. The omission of an excess of vinyl ether results in the hardened mass not being removable within the required timeframe.

[0200] Comparative example 16 uses a reduced amount of vinyl ether, so that the ratio (B.1) to tertiary epoxy is only 0.66:1. In this case too, the mass cannot be removed within the required timeframe.

Claims

Patent claims 1. A hardenable and moisture-removable mass comprising the following components: (A) a tertiary epoxide, (B) a vinyl ether, and (C) a latent acid former for cationic polymerization, wherein component (A) and / or component (B) comprises at least one at least difunctional compound, wherein component (B) is present in a proportion of at least 25 wt%, based on the total mass, and wherein components (B) and (A) are present in a ratio of at least 1.5:1 in the mass, based on the weight fraction of each component in the total mass.

2. Mass according to claim 1, wherein the components (B) and (A) are present in the mass in a ratio of at least 2:1, based on the weight fraction of the respective component in the total weight of the mass.

3. Mass according to claim 1 or 2, wherein the component (A) is present in a proportion of at least 5 wt.%, based on the total weight of the mass.

4. Composition according to any of the preceding claims, wherein the tertiary epoxide is selected from the group consisting of limonene dioxide, limonene-1,2-epoxide and mixtures thereof.

5. Mass according to any one of the preceding claims, wherein the Component (B) comprises at least one at least difunctional connection.

6. Mass according to any one of the preceding claims, wherein the Component (B) is present in a proportion of 25 to 90 wt.%, based on the total weight of the mass.

7. Mass according to any of the preceding claims, wherein the latent acidifier of component (C) comprises a photolatent acid (C1) and / or a thermally latent acidifier (C2).

8. Mass according to one of the preceding claims, wherein the mass further comprises as component (E) at least one chain carrier selected from the group of polyols.

9. Mass according to claim 7 or 8, wherein the mass comprises the following components (A) 5 to 40 wt% of the tertiary epoxide, (B) 25 to 90 wt.% of the vinyl ether, (C) 0.001 to 5 wt% of the latent acidifier; (D) 0 to 50 wt% of a further cationically polymerizable component comprising at least one compound selected from the group consisting of epoxides (D1) that are not tertiary epoxides and oxetanes (D2); (E) 0 to 50 wt.% of the chain carrier; (F) 0 to 70 wt.% of a filler; and (G) 0 to 40 wt.% of an additive.

10. Use of a compound according to any of the preceding claims for producing a releasable bond, a releasable coating or a releasable potting.

11. Use according to claim 10, wherein the bonding, coating or potting is exposed to moisture for a predetermined period of time and at a predetermined temperature after the hardening of the mass, so that the hardened mass is at least partially detached from a substrate.

12. A method for bonding, coating or potting a substrate using a compound according to any one of claims 1 to 9, comprising the following steps: a) metering the compound onto the substrate, b) optionally adding a second substrate to form a substrate composite, whereby the second substrate is brought into contact with the mass, and c) hardening the mass by irradiation with actinic radiation and / or hot hardening to obtain a hardened mass.

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