Method for joining, potting, or coating substrates, and curable compound for this purpose

Abstract

The invention relates: to a method for joining, potting, or coating substrates using a curable compound; to a curable compound; and to a use of the curable compound for joining, potting, or coating substrates. The curable compound comprises: a first curable component (A) and a second curable component (B); a first photoinitiator (C) for the first curable component (A), which first photoinitiator can be activated when irradiated with actinic radiation of a first wavelength λ1; a second photoinitiator (D) for the second curable component (B), which second photoinitiator can be activated when irradiated with actinic radiation of a second wavelength λ2, the second wavelength λ2 being different from the first wavelength λ1; and at least one radical-scavenging inhibitor (E) for scavenging radicals generated when irradiating the curable compound with actinic radiation of the first wavelength λ1. In the method, the curable compound is metered onto a first substrate and activated by irradiating with actinic radiation of the first wavelength λ1. The activated curable compound is then fixed by irradiating with actinic radiation of the second wavelength λ2. The invention also relates to a curable compound and to a use of a curable compound.

Description

[0001] Process for joining, casting or coating substrates and curable mass therefor

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a method for joining, casting or coating substrates using a curable composition which can be activated by irradiation with actinic radiation, a curable composition and the use of such a curable composition.

[0004] TECHNICAL BACKGROUND

[0005] EP 3 894 458 B1 discloses cationically polymerizable compositions with two photoinitiators that can release an acid at different wavelengths. The compositions can be activated by irradiation with a first wavelength and fixed by irradiation with a second wavelength. However, the achievable light-fixation strengths are low. In one embodiment, the cationically polymerizable composition contains one or more acrylates, which, however, already lead to solidification of the composition upon irradiation with the first wavelength, so that the composition can no longer be dosed without restriction.

[0006] In the scientific article by Kostanski et al., "Cationic polymerization using mixed cationic photoinitiator systems" (Designed Monomers and Polymers 2007, Vol. 10, No. 4, pages 327-345, doi: 10.1163 / 156855507781505110), mixtures of sulfonium or iodonium salts with ferrocenium salts are described. The ferrocenium salts serve as sensitizers for the sulfonium- or iodonium-based photoinitiator. A high-pressure mercury vapor lamp is used for irradiation. However, the various photoinitiators in the mixtures are not activated sequentially at specific wavelengths.

[0007] US 4,849,320 A describes a photolithographic process using a mass comprising two photoinitiators and a mixture of radically and cationically polymerizable components. First, the mass is irradiated with radiation of a wavelength suitable for activating the radical photoinitiator in order to initially solidify the mass. The solidified mass is then irradiated with actinic radiation of a wavelength suitable for activating the cationic photoinitiator in order to create structuring in defined areas. In a subsequent washing process, the mass present outside these areas, which was partially cured exclusively by radical means in the first step, is removed. The photoinitiators are selected such that their absorption ranges do not overlap and can be specifically activated separately using different wavelengths.Activation of the radical photoinitiator in the first exposure step leads directly to solidification of the mass.

[0008] US Pat. No. 5,707,780 A also describes compositions comprising mixtures of radically and cationically polymerizable components that can be simultaneously activated by irradiation with an argon laser at different wavelengths. The compositions are characterized by high initial strength after curing, which can be achieved by adjusting the ratio of the extinction coefficients of the radical and cationic photoinitiators. The described compositions can be used in additive manufacturing. Sequential exposure is not disclosed. After exposure, the composition solidifies immediately.

[0009] US Pat. No. 5,472,991 A discloses a process for the two-stage curing of an acrylate-based dental material. The dental materials used contain at least two different photoinitiators that can be sequentially excited by light of different wavelengths. After the first exposure to a wavelength of 450 nm or greater, the dental material is already solidified to such an extent that it can be mechanically modeled into its final shape. Complete curing occurs by irradiation at a second wavelength that is shorter than the first wavelength.

[0010] JP 2017 149 813 A describes radiation-curable acrylate compositions that contain, in addition to at least one (meth)acrylate, two photoinitiators for radical polymerization. Furthermore, the use of styrene-based compounds for targeted control of molecular weight is disclosed. Despite the use of two initiators, separate activation and fixation are not provided.

[0011] US Pat. No. 11,518,087 B2 describes an additive manufacturing process using curable materials containing at least two different types of monomers and at least two photoinitiators with different excitation wavelengths. Selective exposure to a first wavelength leads to at least partial curing of the material. The mechanical behavior of the described systems can be adjusted by selectively controlling the excitation wavelengths. However, the materials have no open time and are not suitable for joining processes.

[0012] WO 2001 092 362 A1 describes photoactivatable coatings based on polyisocyanates, thiols, and a photolatent base. These can be cured within minutes after irradiation or exposure to light, forming a polythiourethane network.

[0013] EP 3 789 416 A1 describes radiation-curable compositions comprising at least one polythiol, one polyisocyanate, one ethylenically unsaturated compound, and a photolatent base. Furthermore, additives such as a photoinitiator for radical polymerization may be included. Curing of the compositions by exposure to different wavelengths is not provided. A process using the composition provides for immediate solidification of the composition upon exposure for the layer-by-layer construction of additively manufactured structures.

[0014] SUMMARY OF THE INVENTION

[0015] The invention is based on the object of avoiding the above-described disadvantages of the processes and compositions known from the prior art and of providing curable compositions that can advantageously be activated in a first irradiation step and fixed in a further irradiation step. In particular, the compositions are intended to enable a process with which the strength build-up can be specifically controlled by light fixation and, at the same time, reliable curing in shadow zones is ensured, particularly in the case of non-transmissible substrates. According to the invention, this object is achieved by a process according to claim 1 using a curable composition, by a curable composition according to claim 7, and by the use of such a composition according to claim 10.

[0016] Further embodiments of the invention are specified in the subclaims, which can optionally be combined with one another.

[0017] The method according to the invention for joining, casting or coating substrates using a curable mass comprises the following steps: a) Providing the curable mass, wherein the curable mass comprises the following components:

[0018] (A) a first curable component selected from the group consisting of cationically polymerizable compounds, addition-curable compounds, moisture-curable compounds, and combinations thereof,

[0019] (B) a second curable component consisting of at least one radically radiation-curable compound,

[0020] (C) a first photoinitiator for the first curable component (A) which is activatable upon irradiation with actinic radiation of a first wavelength Ai, wherein the first photoinitiator is a photolatent acid or a photolatent base,

[0021] (D) a second photoinitiator for the second curable component (B) which is activatable upon irradiation with actinic radiation of a second wavelength A2, wherein the second wavelength A2 is different from the first wavelength Ai, and wherein the second photoinitiator is a free radical former, and

[0022] (E) at least one radical-scavenging inhibitor for scavenging radicals generated upon irradiation of the curable composition with actinic radiation of the first wavelength Ai; b) metering the curable composition onto a first substrate and activating the curable composition by irradiation with actinic radiation of the first wavelength Ai; c) optionally supplying a second substrate to the activated curable composition on the first substrate to form a substrate composite; and d) fixing the activated curable composition by irradiation with actinic radiation of the second wavelength2.

[0023] The process according to the invention is characterized by a precisely controllable activation and curing process for the compound through irradiation at different wavelengths. This process, on the one hand, enables reliable curing even in shadow zones through the (pre-)activation of the first curable component (A) – while simultaneously allowing the activated compound to be processed during an open time. On the other hand, the use of the second curable component (B) based on at least one radically radiation-curable compound creates the possibility of rapid and reliable fixation of the curable compound by irradiation at a second wavelength, with the irradiation taking place in a separate step.

[0024] "Activating" the compound here and below means that the activated compound cures after a specified period of time without further energy input, even in shadowy areas where the compound cannot be irradiated with actinic radiation of the second wavelength. The specified period of time is, in particular, a maximum of 24 hours. Within this period, the compound exceeds the gel point and transitions to the solid state. However, the final curing of the compound does not necessarily have to be complete at this point.

[0025] Final curing refers to a state at which the maximum strength buildup of the mass is complete. This means that the mechanical properties of the mass essentially no longer change. In particular, there is no further increase in the elastic modulus of the mass. Final curing is completed within a maximum of seven days, preferably within three days, and particularly preferably within one day, i.e., within 24 hours.

[0026] In the sense of the method according to the invention, “fixation” or “fixing” refers to the build-up of a strength of the mass beyond which no more flow of the mass can take place, or the degree of strength beyond which joined parts, in particular substrates, can be handled in subsequent processes without causing destruction of the adhesive bond, in particular the substrate bond.

[0027] The use of the radical-scavenging inhibitor (E) ensures that radicals generated in the curable composition during irradiation with actinic radiation of the first wavelength Ai, i.e., during activation of the composition in step b), do not lead to undesired polymerization of the second curable component (B). This prevents further handling of the activated composition during the open time from becoming difficult or impossible, thus providing a particularly flexible process for joining, casting, or coating. This is also possible without relying on formulations of the curable composition in separate packaging units.

[0028] The multi-step process is further enabled by targeted activation of the first photoinitiator (C) and the second photoinitiator (D) at different wavelengths. In other words, the second wavelength A2 is different from the first wavelength Ai.

[0029] Preferably, the second wavelength A2 is shorter than the first wavelength Ai.

[0030] The difference between the wavelength i used for irradiating and activating the first photoinitiator (C) and the wavelength λ2 used for irradiating and activating the second photoinitiator (D) is in particular at least 20 nm, preferably at least 30 nm.

[0031] The same applies to the emission maxima of the radiation sources used for irradiation. The difference between the wavelengths λi and λ2 is preferably chosen so that there is no overlap between the emission spectra of the radiation sources. Monochromatic laser light can be used to irradiate the mass. However, radiation sources that have a singular emission maximum at the respective predetermined wavelength λi or λ2 are preferred.

[0032] The radiation source is preferably an LED curing lamp, as is commercially available.

[0033] The first wavelength Ai lies in particular in a range from 380 to 750 nm, while the second wavelength A2 lies in particular in a range from 200 to 400 nm.

[0034] After the first irradiation with the first wavelength Ai in step b), the mass remains liquid until the end of the open time, as described below. At the same time, irradiation with the first wavelength Ai, i.e., the activation of the first photoinitiator (C), ensures that a polymerization reaction is initiated in the first curable component (A), which enables reliable final curing even in shadow zones, even if the shadow zones may no longer be accessible during subsequent irradiation.

[0035] Accordingly, in one embodiment, step d) can be carried out within a processing time that preferably corresponds at most to the open time of the curable composition after activation of the curable composition by irradiation with actinic radiation of the first wavelength i. This enables particularly flexible process control without having to accept disadvantages with regard to the strength build-up during final curing.

[0036] The molar ratio of inhibitor (E) to first photoinitiator (C) in the curable composition is in particular in a range from 0.4:1 to less than 20:1, preferably in a range from 0.4:1 to less than 10:1 or 1:1 to 10:1, particularly preferably in a range from 1:1 to 5:1.

[0037] An excessively low molar fraction of the inhibitor (E), based on the first photoinitiator (C), can lead to masses which already after the first irradiation, i.e. the irradiation of the mass with actinic radiation of the first wavelength Xi, become at least partially solid and are no longer joinable, in particular due to a polymerization of the second curable component (B) which is undesired at this time.

[0038] If, however, the inhibitor (E) is used in too high a proportion or in too large an excess of the amount of substance, this can lead to the curable composition not being able to build up sufficient fixing strength when irradiated with actinic radiation of the second wavelength A2, since the radicals generated by the second photoinitiator (D) are intercepted to an excessive extent by the inhibitor (E) and are therefore not available for the polymerization of the second curable component (B).

[0039] In order to achieve a particularly high fixing strength after irradiation with actinic radiation of the second wavelength A2, the molar ratio of inhibitor (E) to second photoinitiator (D) in the curable composition can be 1:2 or less, preferably 1:5 or less, particularly preferably 1:10 or less.

[0040] In step b), the curable composition is metered onto the first substrate and activated by irradiation with actinic radiation of the first wavelength Ai. The order of metering and activation in step b) depends solely on the metering and exposure device used in the respective process. Thus, the curable composition can first be metered onto the first substrate and then activated by irradiation with actinic radiation of the first wavelength Ai. When using a so-called flow-through apparatus, the activation of the curable composition can occur before metering onto the first substrate. Suitable metering devices for flow-through activation of the curable composition by irradiation are described in DE 3 702 999 A1 and DE 10 2007 017 842 A1.

[0041] Between steps b) and d), the second substrate can optionally be added to the activated curable mass on the first substrate as step c). In particular, the two substrates are then aligned with each other. Thus, in the process according to the invention, the substrates to be joined can be precisely aligned with each other within the open time. This is particularly important for joining processes for the production of electro-optical components, such as camera modules. The second irradiation step d) subsequently fixes the activated mass and thus converts it into a dimensionally stable state.

[0042] Other particularly suitable substrates for bonding are displays, sensors, electronic components and housings.

[0043] The process according to the invention also makes it possible to achieve reliable curing or fixing of the activated mass at room temperature without additional heat input. However, this does not preclude the possibility of accelerating the curing process by heating the fixed mass.

[0044] In one variant, the method therefore further comprises the following step: e) heating the fixed curable mass on the first substrate or in the substrate composite.

[0045] In other words, the process according to the invention can optionally comprise an additional tempering step, which serves in particular to achieve faster curing or to accelerate the achievement of the final strength of the mass.

[0046] It may also be advantageous to heat the curable mass when providing it in step a) and / or to heat one or more of the substrates before dosing the curable mass in step b) and / or before joining in step c), whereby the final curing can also be accelerated.

[0047] It is also possible for steps d) and e) to be carried out simultaneously, i.e. for the activated curable mass to be fixed by irradiation with actinic radiation of the second wavelength λ2, while the curable mass is heated on the substrate or in the substrate composite.

[0048] The invention further relates to a curable mass which can be used in particular in the above-described method according to the invention for joining, casting or coating substrates.

[0049] The above-described statements regarding the process according to the invention apply accordingly to the curable composition according to the invention and vice versa.

[0050] The curable composition according to the invention for joining, casting or coating substrates comprises the following components: (A) a first curable component selected from the group consisting of cationically polymerizable compounds, addition-crosslinkable compounds, moisture-crosslinkable compounds and combinations thereof,

[0051] (B) a second curable component consisting of at least one radically radiation-curable compound,

[0052] (C) a first photoinitiator for the first curable component (A) which is activatable upon irradiation with actinic radiation of a first wavelength Ai, wherein the first photoinitiator is a photolatent acid or a photolatent base,

[0053] (D) a second photoinitiator for the second curable component (B) which is activatable upon irradiation with actinic radiation of a second wavelength A2, wherein the second wavelength A2 is different from the first wavelength Ai, and wherein the second photoinitiator is a free radical former, and

[0054] (E) at least one radical-scavenging inhibitor for scavenging radicals generated upon irradiation of the curable composition with actinic radiation of the first wavelength Ai.

[0055] Compared to the prior art, the compositions according to the invention are characterized in that they enable high light-fixing strength and light-fixing speed, while at the same time they are suitable for a controlled curing process, which can be controlled by irradiating the curable compositions in a multi-stage process.

[0056] Furthermore, the invention relates to the use of the curable mass as described above for joining, casting or coating substrates.

[0057] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0058] The invention is described in detail below using preferred embodiments by way of example, which, however, are not intended to be limiting. "One-component" or "one-component composition" in the context of the invention means that the aforementioned components of the composition are present together in one package unit.

[0059] In the context of the invention, “liquid” means that at 23 °C the loss modulus G” determined by viscosity measurement is greater than the storage modulus G' of the mass in question.

[0060] The "open time" refers to the time after the first irradiation of the curable material, i.e., after irradiation with actinic radiation of the first wavelength Ai, during which the activated material has not yet passed its gel point. During this time, the material only changes its properties in terms of viscosity and adhesion insignificantly. Joining a second substrate is possible within the open time.

[0061] The open time is limited by the time of thread pull and / or, at the latest, by the time until a skin forms, which can be determined by haptic measurement. Within the open time, the process according to the invention can be carried out reliably.

[0062] However, it is also possible that the activated masses remain at least partially joinable beyond the specified open time before they solidify to such an extent that no further flow or pressing onto another substrate is possible.

[0063] In order to enable a robust process, the feeding of a second substrate in step c) of the method according to the invention, if carried out, is preferred within the open time.

[0064] In addition to the composition of the curable mass, the open time can be influenced by, among other things, the irradiated energy dose and the temperature.

[0065] Where the indefinite article “ein” or “eine” is used, this also includes the plural form “ein or mehr” unless this is expressly excluded.

[0066] "At least difunctional" means that each molecule contains two or more units of the respective functional group. Unless otherwise stated, all weight proportions listed below refer to the total weight of the compound.

[0067] In the following, equivalents refer to 1 equivalent of the functional group and are given in relation to each other.

[0068] In a first embodiment, the curable composition for carrying out the process according to the invention contains, in addition to components (B) to (E), at least one cationically polymerizable compound (A1) as the first curable component (A). Preferably, the first photoinitiator (C) of the curable composition of the first embodiment is a photolatent acid (C1).

[0069] In a second embodiment, the curable composition for carrying out the process according to the invention contains, in addition to components (B) to (E), at least one addition-crosslinkable compound (A2) as the first curable component (A). Preferably, the first photoinitiator (C) of the curable composition of the second embodiment is a photolatent base (O2).

[0070] In a third embodiment, the curable composition for carrying out the process according to the invention contains, in addition to components (B) to (E), at least one moisture-crosslinkable compound (A3) as the first curable component (A). Preferably, the first photoinitiator (C) of the curable composition of the third embodiment is a photolatent acid (O1).

[0071] The individual components of the curable mass, which can be used in particular in the process according to the invention, are described in more detail below.

[0072] Component (A): First curable component

[0073] The curable composition comprises a first curable component (A) selected from the group consisting of cationically polymerizable compounds (A1), addition-crosslinkable compounds (A2), moisture-crosslinkable compounds (A3) and combinations thereof.

[0074] The components described below can thus be used alone or in combination with one another as component (A). The first curable component (A), through its respective components in interaction with the first photoinitiator (C) matched to the first curable component (A), provides a curing mechanism that enables delayed final curing of the curable composition, even in shadowy areas.

[0075] Suitable cationically polymerizable compounds (A1) preferably comprise one or more at least difunctional epoxy-containing compounds. At least "difunctional" means that the epoxy-containing compound contains at least two epoxy groups.

[0076] Component (A1) may comprise, for example, cycloaliphatic epoxides, aromatic and aliphatic glycidyl ethers, glycidyl esters or glycidylamines and mixtures thereof.

[0077] Difunctional cycloaliphatic epoxy resins are known in the art and include compounds that carry 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,

[0078] Bis(3,4-epoxycyclohexylmethyl)adipate, dicyclopentadiene dioxide and 1,2-epoxy-6-(2,3-epoxypropoxy)hexahydro-4,7-methanindane and mixtures thereof.

[0079] Aromatic epoxy resins can also be used. Examples of aromatic epoxy resins are bisphenol A epoxy resins, bisphenol F epoxy resins, phenol novolak epoxy resins, cresol novolak epoxy resins, biphenyl epoxy resins, 4,4'-biphenyl epoxy resins,

[0080] Divinylbenzene dioxide, 2-glycidylphenyl glycidyl ether, naphthalenediol diglycidyl ether, glycidyl ether of tris(hydroxyphenyl)methane, and glycidyl ether of tris(hydroxyphenyl)ethane, as well as mixtures thereof. Furthermore, all fully or partially hydrogenated analogues of aromatic epoxy resins can also be used.

[0081] Isocyanurates and other heterocyclic compounds substituted with epoxy groups can also be used in the curable composition. Examples include triglycidyl isocyanurate and monoallyl diglycidyl isocyanurate.

[0082] In addition, polyfunctional epoxy resins of all the resin groups mentioned, tough, elasticized epoxy resins and mixtures of different epoxy resins can also be used in the composition according to the invention.

[0083] Also within the meaning of the invention is a combination of several epoxy-containing compounds, of which at least one is di- or higher-functional.

[0084] In addition to at least difunctional epoxy-containing compounds, monofunctional epoxides can also be used as reactive diluents.

[0085] Examples of commercially available epoxy-containing compounds are products sold under the trade names CELLOXIDE™ 2021 P, CELLOXIDE™ 8000 by Daicel Corporation, Japan, as EPIKOTE™ RESIN 828 LVEL, EPI KOTE™ RESIN 166, EPI KOTE™ RESIN 169 by Momentive Specialty Chemicals BV, Netherlands, as Epilox™ resins of the product series A, T and AF by Leuna Harze, Germany, or as EPICLON™ 840, 840-S, 850, 850-S, EXA850CRP, 850-LC by DIC KK, Japan, Omnilane 1005 and Omnilane 2005 by IGM Resins BV, Syna Epoxy 21 and Syna Epoxy 06 by Synasia Inc., TTA21 , TTA26, TTA60 and TTA128 from Jiangsu Tetra New Material Technology Co. Ltd., and THI-DE, DE-102 and DE-103 from Nippon Oil.

[0086] Instead of or in addition to epoxy-containing compounds, oxetane-containing compounds can also be used as cationically polymerizable compounds (A1) in the curable composition. Processes for the preparation of oxetanes are known, in particular, from US 2017 / 0198093 A1.

[0087] Examples of commercially available oxetanes are bis(1-ethyl-3-oxetanylmethyl)ether (DOX), 3-allyloxymethyl-3-ethyloxetane (AQX), 3-ethyl-3-[(phenoxy)methyloxetane (POX), 3-ethyl-3-hydroxymethyloxetane (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.

[0088] The epoxides and / or oxetanes of the composition according to the invention, in particular for use in the process according to the invention, are preferably curable by a cationic photoinitiator (C1), which will be described in more detail later.

[0089] Instead of or in addition to epoxides or oxetanes, vinyl ethers can also be used as the cationically polymerizable component (A1) in the composition of the invention. Suitable vinyl ethers are trimethylolpropane trivinyl ether, ethylene glycol divinyl ether, and cyclic vinyl ethers, as well as mixtures thereof. Furthermore, vinyl ethers of polyfunctional alcohols can be used.

[0090] Finally, the cationically polymerizable component (A1) can comprise one or more alcohols used as reactive flexibilizers. Higher molecular weight polyols, in particular, can be used to flexibilize compositions containing at least one cationically polymerizable compound. Suitable polyols are available, for example, based on polyethers, polyesters, polycaprolactones, polycarbonates, or (hydrogenated) polybutadienediols.

[0091] Examples of commercially available higher molecular weight polyols are products sold 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] The list of cationically polymerizable compounds (A1) is to be considered exemplary and not exhaustive. A mixture of the cationically polymerizable compounds (A1) mentioned is also within the scope of the invention.

[0093] Instead of component (A1), the composition according to the invention may also contain addition-crosslinkable compounds (A2).

[0094] The addition-crosslinkable compound (A2) preferably comprises an isocyanate (A2-1) together with an isocyanate-reactive compound. The group of suitable isocyanates (A2-1) includes aliphatic, cycloaliphatic, heterocyclic, and aromatic isocyanates.

[0095] Preferably, the isocyanate (A2-1) is at least difunctional.

[0096] Examples of suitable polyisocyanates are: dimeric 2,4-diisocyanatotoluene, dimeric 4,4'-diisocyanatodiphenylmethane, 3,3'-diisocyanato-4,4'-dimethyl-N,N'-diphenylurea, the isocyanurate of isophorone diisocyanate, hexamethylene diisocyanate and its isocyanurate, pentamethylene diisocyanate and its isocyanurate, 1,4-phenylene diisocyanate, naphthalene-1,5-diisocyanate and addition products of diisocyanates with short-chain diols such as 1,4-butanediol or 1,2-ethanediol.

[0097] Furthermore, addition products of diisocyanates with polyethers, polyesters, polycarbonates, polybutadienes or other alcohols, amines or thiols can be used.

[0098] Preferred are isocyanurates of hexamethylenediamine, pentamethylenediamine or isophorodinamine as well as addition products of hexamethylenediamine or isophoronediamine with OH-terminated polymers.

[0099] The isocyanates (A2-1) can be used alone or in a mixture of two or more of the isocyanates.

[0100] The addition-crosslinkable compound (A2) may comprise at least one thiol (A2-2) as an isocyanate-reactive compound. The thiol (A2-2) is preferably an at least difunctional thiol.

[0101] Preferably, the at least difunctional thiol is selected from the group consisting of ester-based thiols, polyethers with reactive thiol groups, polythioethers, polythioether acetals, polythioether thioacetals, polysulfides, thiol-terminated urethanes, thiol derivatives of isocyanurates and glycoluril, and combinations thereof.

[0102] Examples of commercially available ester-based thiols based on 2-mercaptoacetic acid include trimethylolpropane trimercaptoacetate,

[0103] Pentaerythritol tetramercaptoacetate and glycol dimercaptoacetate, available under the brand names Thiocure™ TMPMA, PETMA, and GDMA from Bruno Bock, respectively. Other examples of commercially available ester-based thiols include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutylate), glycol di(3-mercaptopropionate), and tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate, available under the brand names Thiocure™ TMPMP, PETMP, GDMP, and TEMPIC from Bruno Bock.

[0104] Examples of commercially available (thio)ether-based thiols include DMDO (1,8-dimercapto-3,6-dioxaoctane), available from Arkema SA, DMDS (dimercaptodiethyl sulfide) and DMPT (2,3-di((2-mercaptoethyl)thio)-1-propane-thiol), both available from Bruno Bock.

[0105] With regard to increased resistance of the cured compound to temperature and humidity, the use of ester-free thiols is particularly preferred. Examples of ester-free thiols can be found in JP 2012 153 794 A, which is incorporated into the description by reference.

[0106] The preferred composition is tris(3-mercaptopropyl)isocyanurate (TMPI) as a trifunctional, ester-free thiol. This thiol has been shown to provide both good hydrolytic stability and improve adhesion to various substrates.

[0107] According to a particularly preferred embodiment, the at least difunctional thiol of component (A2-1) therefore comprises tris(3-mercaptopropyl)isocyanurate, alone or in a mixture with other at least difunctional thiols.

[0108] Ester-free thiols based on a glycoluril compound are known from EP 3 075 736 A1. These can also be used in the compositions of the invention as further addition-crosslinkable resin components, alone or in a mixture with other at least difunctional thiols.

[0109] Ester-free thiols based on olefins or terpenes are disclosed in US Pat. No. 9,340,716 B2. These can also be used in the compositions of the invention as further addition-crosslinkable resin components, alone or in a mixture with other at least difunctional thiols. Higher-functional thiols, obtainable, for example, by oxidative dimerization processes of at least difunctional thiols, can also be used.

[0110] Furthermore, at least difunctional thiols can be synthesized by reacting at least difunctional thiiranes with a thiol.

[0111] Those skilled in the art know that primary thiols react more rapidly with isocyanates than secondary or tertiary thiols. Depending on the process design, primary thiols may be advantageous because they enable faster curing, while secondary or tertiary thiols may be preferred in processes requiring a longer open time.

[0112] Instead of components (A1) and (A2), the composition according to the invention may also contain moisture-crosslinkable compounds (A3).

[0113] Preferably, the moisture-crosslinkable compound (A3) is selected from the group of silanes.

[0114] Suitable silanes include monofunctional, particularly low-molecular-weight silanes, di- or higher-functional silane-modified oligomers and / or polymers. These are not further restricted structurally.

[0115] Examples of silane-modified polymers used include polyethers or polyacrylates with terminal alkoxysilane groups. At least difunctional γ-alkoxysilanes are preferred. Their preparation is described in detail, for example, in US Pat. No. 5,364,955 and the documents cited therein.

[0116] γ-Alkoxysilanes with at least two alkoxysilane-containing end groups are commercially available, for example, from Kaneka Belgium NV under the names Kaneka MS Polymer or Kaneka Silyl. Polyether-based γ-Alkoxysilanes are also available from Wacker Chemie AG under the names Geniosil STP-E15 and STP-E35.

[0117] Instead of or in addition to γ-alkoxysilanes, so-called α-alkoxysilane compounds can also be used. At least difunctional α-alkoxysilane compounds are preferred. The preparation of α-alkoxysilane-terminated compounds is described in detail in WO 03 / 014226 A1, among others. In addition, many of the preferred α-silanes based on polyethers or polyurethanes are commercially available from Wacker Chemie AG. These are marketed under the brand name GENIOSIL STP-E. Examples include the types Geniosil STP-E10 and STP-E30.

[0118] In addition to moisture-crosslinkable polymeric compounds, monofunctional low-molecular-weight alkoxysilane compounds can also be used. These alkoxysilanes contain a monovalent organic moiety and are generally used to increase storage stability and improve adhesion or flexibility.

[0119] Suitable monofunctional y-alkoxysilanes with different organic radicals are available, for example, under the trade names Dynasylan VTMO, Dynasylan GLYMO, Dynasylan MEMO, Dynasylan MTMS from Evonik Industries AG.

[0120] Examples of commercially available monofunctional a-alkoxysilanes include products from Wacker Chemie AG. Corresponding methacrylate- or carbamate-functionalized a-alkoxysilanes are available under the names GENIOSIL XL 32, XL 33, XL 63, or XL 65. Higher molecular weight monofunctional alkoxysilanes can also be used. Such compounds are typically used for flexibilization and can be purchased from Wacker Chemie AG, for example, under the names Geniosil XM 20 and XM25.

[0121] Partially condensed monofunctional alkoxysilanes can also be used. Such products are commercially available, for example, under the names Dynasylan 6490 or Dynasylan 1146 from Evonik Industries AG.

[0122] In the present compositions, one or more of the alkoxysilanes mentioned can be used as moisture-crosslinkable compound (A3).

[0123] Mixtures of the above-mentioned α-alkoxysilanes and / or γ-alkoxysilanes can also be advantageously used for compositions for use in the process according to the invention. The first curable component (A) is present in the composition, based on the total weight of the composition, in particular in a proportion of 5 to 90 wt.%, preferably in a proportion of 10 to 85 wt.%.

[0124] Component (B): Second curable component

[0125] The compositions according to the invention comprise a second curable component (B) consisting of at least one radically radiation-curable compound.

[0126] The second curable component (B) serves in particular to enable rapid, precise, controllable and reliable fixing of the already activated mass by irradiation with actinic radiation of the second wavelength λ2, in particular at the latest as soon as the end of the open time of the activated mass is reached.

[0127] The radically radiation-curable compound (B) is not further restricted structurally as long as it contains ethylenically unsaturated double and / or triple bonds.

[0128] Suitable examples include (meth)acrylates, allyl compounds, vinyl compounds, methallyl compounds, isoprenes, butadienes and propargyls.

[0129] The compositions preferably contain at least one difunctional radically radiation-curable compound.

[0130] Radiation-curable compounds based on (meth)acrylates are preferred. For example, both aliphatic and aromatic (meth)acrylates can be used.

[0131] Here and in the following, (meth)acrylates are referred to as derivatives of acrylic acid and methacrylic acid as well as combinations and mixtures thereof.

[0132] Suitable examples are the following radiation-curable compounds: isobornyl acrylate, stearyl acrylate, tetrahydrofurfuryl acrylate, cyclohexyl acrylate, 3,3,5-trimethylcyclohexanol acrylate, behenyl acrylate, 2-methoxyethyl acrylate and other mono- or polyalkoxylated alkyl acrylates, isobutyl acrylate, isooctyl acrylate, lauryl acrylate, tridecyl acrylate, isostearyl acrylate, 2-(o-phenylphenoxy)ethyl acrylate, acryloylmorpholine, N,N-dimethylacrylamide, 4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,10-decanediol diacrylate, tricyclodecanedimethanol diacrylate, dipropylene glycol diacrylate,

[0133] Tripropylene glycol diacrylate, polybutadiene diacrylate, cyclohexanedimethanol diacrylate, diurethane acrylates of monomeric, oligomeric, or polymeric diols and polyols, trimethylolpropane triacrylate (TMPTA), and dipentaerythritol hexaacrylate (DPHA), and combinations thereof. Higher-functional acrylates derived from multiply branched or dendrimeric alcohols can also be used advantageously.

[0134] The analogous methacrylates are also within the meaning of the invention.

[0135] Radiation-curable compounds containing allyl groups are also suitable, such as 1,3,5-triallyl-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, which is commercially available as TAICROS® from Evonik. Compounds containing allyl groups lead to rapid fixation processes when irradiated at the second wavelength X2, particularly in the presence of thiols.

[0136] Unhydrogenated polybutadienes with free double bonds, such as the Poly BD® types, can also be used as radiation-curing compounds.

[0137] Urethane acrylates based on polyesters, polyethers, polycarbonate diols and / or (hydrogenated) polybutadiene diols can be used as higher molecular weight radiation-curable compounds in the second curable component (B).

[0138] Furthermore, radiation-curable hybrid compounds can be used which have both radically polymerizable groups and cationically polymerizable epoxy groups.

[0139] Examples of commercially available products that contain both radically polymerizable groups and cationically polymerizable epoxy groups include 3,4-epoxycyclohexyl methyl methacrylate (TTA15) from Jiangsu Tetra New Material Technology Co., Ltd., UVACURE 1561 from UCB, Solmer SE 1605 from Melrob Ltd., and Miramer PE210HA from Miwon Europe GmbH. The radiation-curable hybrid compounds mentioned can be used advantageously, particularly in curable compositions according to the first embodiment.

[0140] Furthermore, radiation-curable hybrid compounds can be used which have both radically polymerizable groups and addition-crosslinkable groups.

[0141] Examples of suitable hybrid compounds further include hydroxy(meth)acrylates, isocyanato(meth)acrylates, epoxy(meth)acrylates, vinyl ether(meth)acrylates or oxetane(meth)acrylates.

[0142] Examples of commercially available products that contain both radically polymerizable groups and addition-crosslinkable groups include Karenz MOI and Karenz AOI from Resonac, Laromer PR 9000 from BASF, glycidyl methacrylate, Ebecryl 4141 and Ebecryl 4596 from Allnex.

[0143] The radiation-curable hybrid compounds mentioned can be used advantageously in particular in masses according to the second embodiment.

[0144] A combination of several radiation-curable compounds is also within the scope of the invention.

[0145] The second curable component (B) is present in the composition according to the invention in particular in a proportion of 5 to 50 wt.%, preferably in a proportion of 10 to 40 wt.%, in each case based on the total weight of the curable composition.

[0146] Component (C): First photoinitiator

[0147] The curable composition comprises a first photoinitiator (C), which is a photolatent acid (C1) or a photolatent base (C2).

[0148] The first photoinitiator (C) is activated upon irradiation with actinic radiation of a first wavelength i and initiates a polymerization reaction in the curable composition, enabling reliable final curing even in shadowy areas. In this context, the first photoinitiator (C) is specifically matched to the first curable component (A). This means that the polymerization reaction of the first curable component (A) is determined in particular by the activation of the first photoinitiator (C).

[0149] The photolatent acid (C1) preferably comprises at least one photolatent acid generator which releases an acid upon irradiation with actinic radiation of a first wavelength i, and in particular a photolatent acid generator based on a metallocenium compound for cationic polymerization.

[0150] An overview of various metallocenium salts is disclosed in EP 0 542 716 B1. Examples of different anions of the metallocenium salts include HSOr, PFe', SbFe', AsFe', Cl', Br, |-, ClO4', POr, SChCF5', tosylate, aluminates, or a borate anion, such as BF4' and B(C6F5)4'.

[0151] Preferably, the photolatent acid (C1) based on a metallocenium compound is selected from the group of ferrocenium salts.

[0152] Examples of suitable ferrocenium salts are cumenylcyclopentadienyliron(II) hexafluorophosphate (Irgacure 261); naphthalenylcyclopentadienyliron(II) hexafluorophosphate, benzylcyclopentadienyliron(II) hexafluorophosphate and cyclopentadienylcarbazoleiron(II) hexafluorophosphate.

[0153] The photolatent acid (C1) preferably absorbs in the visible range of the electromagnetic spectrum. This means that the photolatent acid (C1) is preferably activatable at a first wavelength i > 380 nm. The photolatent acid (C1) can preferably be activated by radiation with a wavelength of i > 400 nm, preferably i > 460 nm.

[0154] Particularly preferably, the first wavelength i, i.e. the activation wavelength of the curable mass, is in a range from 400 to 750 nm.

[0155] Suitable photolatent bases (C2) preferably include one or more compounds and derivatives derived from the group of cyclic amidine bases, cyclic guanidine bases, alpha-aminoacetophenones, dihydropyridines, imidazolium compounds, carbamates, biguanidinium compounds, and mixtures thereof. The corresponding salts of the aforementioned substance classes are also suitable as photolatent bases (C2).

[0156] Cyclic amidine bases include compounds based on 1,5-diazabicyclo[4.3.0]nonene, 1,8-diazabicyclo[5.4.0]undecene, 1,11-diazabicyclo[8.4.0]tetradecene, such as 1,8-diazabicyclo[5.4.0]undec-7-ene-anthracene-tetraphenylborate.

[0157] Structural analogues such as 2,3,4,6,7,8-hexahydropyrrolo[1,2-a]pyrimidin-1-ium tetraphenylborate, 1-(anthracen-9-ylmethyl)-2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepin-1-ium tetraphenylborate or 1-(anthracen-9-ylmethyl)-2,3,4,6,7,8-hexahydropyrrolo[1,2-a]pyrimidin-1-ium tetraphenylborate can also be used advantageously.

[0158] Examples of cyclic guanidine bases can be selected from the group of bicyclic guanidine compounds and include, for example, 1,5,7-triazabicyclo[4.4.0]dec-5-ene-H-tetraphenylborate, 1-(anthracen-9-ylmethyl)-9-ethyl-3,4,6,7,8,9-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-ium tetraphenylborate and 3,4,6,7,8,9-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-ium tetraphenylborate.

[0159] Suitable alpha-aminoacetophenones include, for example, 2-benzyl-2-(dimethylamino)-1-(4-methoxyphenyl)butan-1-one, 2-benzyl-2-dimethylamino-4'-morpholinobutyrophenone, and 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-ylphenyl)butan-1-one. Further compounds can be found in EP 0 284 561 B1.

[0160] Examples of photolatent bases based on dihydropyridine are N-methylnifedipine, N-butyl-2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid diethyl ester and N-methyl-2,6-dimethyl-4-(4,5-dimethoxy-2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid diethyl ester.

[0161] A suitable photolatent base based on an imidazolium compound is 3-(anthracen-9-ylmethyl)-1-methyl-1 H-imidazol-3-ium tetraphenylborate.

[0162] A suitable photolatent base based on a carbamate is anthracen-9-ylmethyldiethylcarbamate. Examples of photolatent bases based on biguanidinium compounds are 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidium n-butyltriphenylborate, (Z)-([bis(dimethylamino)methylidene]amino)-N-cyclohexyl(cyclohexylamino)methaniminium tetrakis(3-fluorophenyl)borate, and 1,2-diisopropyl-3-[bis(dimethylamino)methylene]guanidium 2-(3-benzoylphenyl)propionate.

[0163] The compounds mentioned are commercially available under the name CGI 277 from BASF SE, Irgacure 369, Irgacure 907, Irgacure 379 each from IGM Resins and WPBG-345, WPBG-300, WPBG-266, WPBG-018 from Wako Chemicals Europe GmbH.

[0164] The decomposition products of the photolatent base (C2) preferably have a pKs greater than 7 after irradiation with actinic radiation of the first wavelength Ai. Activation of the photolatent base (C2) changes the pKs by at least one.

[0165] The photolatent base (C2) preferably absorbs in the visible range of the electromagnetic spectrum. This means that the photolatent base (C2) is preferably activated at a first wavelength i > 380 nm. Preferably, the photolatent base (C2) can be activated by radiation with a wavelength Ai > 400 nm.

[0166] The first photoinitiator (C), i.e. the photolatent acid (C1) or the photolatent base (C2), is contained in particular in a proportion of 0.01 to 5 wt.%, based on the total weight of the curable composition, but preferably in proportions of 0.05 to 3 wt.%.

[0167] Component (D): Second photoinitiator

[0168] In addition to components (A), (B), and (C), the composition, particularly for use in the process according to the invention, contains a second photoinitiator (D) for the radical polymerization of component (B). The second photoinitiator (D) is accordingly a radical generator.

[0169] In the process according to the invention, the second photoinitiator (D) enables the fixing of the composition previously activated in step b) by irradiation with actinic radiation of the second wavelength λ2. In other words, the second photoinitiator (D) forms radicals under the action of the actinic radiation of the second wavelength λ2, which result in or trigger polymerization of the second curable component (B).

[0170] As the second photoinitiator (D), all customary, commercially available compounds can be used, such as, for example, a-hydroxyketones, benzophenone, a,a'-diethoxyacetophenone, 4,4-diethylaminobenzophenone, 2,2-dimethoxy-2-phenylacetophenone, 4-isopropylphenyl-2-hydroxy-2-propylketone, 1-hydroxycyclohexylphenylketone, isoamyl-p-dimethylaminobenzoate, methyl-4-dimethylaminobenzoate, methyl-o-benzoylbenzoate, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-isopropylthioxanthone, dibenzosuberone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bisacylphosphine oxides, wherein the said compounds alone or in combination of two or more of the said compounds can be used as a second photoinitiator (D).

[0171] As a second photoinitiator (D), which can be activated by UV radiation, the IRGACURE TM-Types from BASF SE are used, such as the types IRGACURE 184, IRGACURE 500, IRGACURE 1179, IRGACURE 2959, IRGACURE 745, IRGACURE 651, IRGACURE 369, IRGACURE 907, IRGACURE 1300, IRGACURE 819, IRGACURE 819DW, IRGACURE 2022, IRGACURE 2100, IRGACURE 784, IRGACURE 250, IRGACURE TPO, IRGACURE TPO-L. Furthermore, the DAROCUR TM -Types from BASF SE can be used, such as the types DAROCUR MBF, DAROCUR 1173, DAROCUR TPO and DAROCUR 4265.

[0172] The above lists are to be seen as examples for the second photoinitiator (D) and should not be understood as limiting.

[0173] The second photoinitiator used as component (D) in the compositions according to the invention can preferably be activated by actinic radiation having a wavelength of 200 to 400 nm, particularly preferably 250 to 380 nm.

[0174] The second photoinitiator (D) is preferably selected such that it is not activated upon irradiation of the curable composition at the first wavelength i. According to the invention, the second photoinitiator (D) is activated in the process according to the invention by irradiating the composition at the second wavelength A2.

[0175] If required, the second photoinitiator (D) can be combined with a suitable sensitizer.

[0176] The difference between the wavelength i used for irradiating and activating the first photoinitiator (C) and the wavelength A2 used for irradiating and activating the second photoinitiator (D) is in particular at least 20 nm, preferably at least 30 nm.

[0177] The second photoinitiator (D) is present in the compositions in particular in a proportion of 0.01 to 5 wt.%, preferably 0.5 to 3 wt.%, in each case based on the total weight of the composition.

[0178] The sum of the proportions of the first photoinitiator (C) and the second photoinitiator (D), based on the total weight of the mass, is in particular at most 10 wt.%, preferably at most 5 wt.%.

[0179] Component (E): Inhibitor

[0180] In addition to components (A) to (D), the curable composition, in particular for use in the process according to the invention, contains as an essential constituent at least one inhibitor (E) for scavenging radicals generated upon irradiation of the curable composition with actinic radiation of the first wavelength Ai.

[0181] Thus, the inhibitor (E) ensures that the curable mass, when irradiated with actinic radiation of the first wavelength i, has an open time within which the activated mass remains dosable or joinable.

[0182] This effect is attributed in particular to the fact that the inhibitor (E) ensures that any radicals formed in the composition during irradiation with the first wavelength i do not lead to a significant increase in the viscosity of the curable composition, in particular as a result of polymerization reactions of the second curable component (B) which are still undesirable at this point in time in the process according to the invention.

[0183] The inhibitor is further selected with respect to its proportion in the curable mass such that when the already activated mass is irradiated with the second wavelength Ä2in step d) by the second photoinitiator (D), a sufficient amount of radicals is formed which enable the polymerization of the second curable component (B) and thus lead to a fixation of the mass.

[0184] Thus, the inhibitor (E) can be viewed as a radical scavenger that, on the one hand, protects the radiation-curable component (B) from premature conversion at the time of activation of the first curable component (A), and, on the other hand, is consumed by the radicals formed upon activation of the second photoinitiator (D), thus enabling the targeted conversion of the radiation-curable component (B) at the desired time. In other words, the inhibitor (E) ensures that the radiation-curable component (B) does not cure for at least the duration of the open time. Thus, the open time can be controlled by the proportion and type of inhibitor (E).

[0185] Depending on the proportion of the inhibitor (E) in the mass, the irradiation dose for activating the first photoinitiator (C) and / or its proportion in the mass can be varied, and vice versa.

[0186] Preferably, the irradiation dose, the proportion of the first photoinitiator (C) and the proportion of the inhibitor (E) are adjusted to one another in such a way that the mass remains liquid during the open time after activation of the first photoinitiator (C).

[0187] Furthermore, the curing behavior of the mass can be further controlled via the ratio of the proportions of the inhibitor (E) and the second photoinitiator (D) and / or the irradiation dose for activating the second photoinitiator (D), since the consumption of the inhibitor (E) is faster the more radicals are generated from the second photoinitiator (D) in this step.

[0188] The inhibitor (E) is not further structurally restricted. For example, the inhibitor (E) comprises one or more compounds selected from the group consisting of hindered phenols, thioethers, phosphites, hindered amines (HALS), optionally substituted styrenes, nitrous acid esters, alkyl nitrites, dithiocarbamates, and combinations thereof.

[0189] Examples of suitable inhibitors (E) are 2,6-di-tert-butyl-4-methylphenol, 4-methoxyphenol, 1,4-dihydroxybenzene, 1,4-benzoquinone, (2,2,6,6-tetramethylpiperidinyl-1-1)oxyl, isoeugenol, a-tocopherol, 4-tert-butylcatechol, 1,2,3-trihydroxybenzene, 3,4,5-trihydroxybenzoic acid, lauryl gallates

[0190] (dodecyl gallate), triphenyl phosphite, phenylphosphonic acid, tris(2,4-di(tert-butyl)-phenyl)phosphite, 2,2-diphenyl-1-picryl-hydrazyl, phenothiazine, 2-methylpropyl nitrite, 2-propyl nitrite, bis(1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5- bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, sebacic acid bis-(2,2,6,6-tetramethyl-4-piperidyl ester), 3,5-dimethylperhydro-1,3,5-thiadiazine-2-thione and N-nitroso-N-phenylhydroxylaminato) aluminum salts.

[0191] Furthermore, 1,1-diphenylethylene, a-methylstyrene, tert-butyl nitrite, tetraethylthiuram disulfide and 2,4-diphenyl-4-methyl-1-pentene can advantageously be used in the curable composition, in particular for carrying out the process according to the invention.

[0192] Furthermore, CTA reagents (chain transfer agents), typically used for RAFT polymerizations, can be used as inhibitors (E). Examples include dithiobenzoates such as benzyl benzodithioate, trithiocarbonates such as S,S-dibenzyl trithiocarbonate, and dithiocarbamates such as tetraethylthiuram disulfide (TEDS) and tetramethylthiuram disulfide.

[0193] In some cases, the inhibitor (E) may also include hexaarylbiimidazoles (HABI) or derivatives thereof. Typical commercially available hexaarylbiimidazoles are 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole (BCIM HABI), 2,2'-bis(2-methoxyphenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2-(2- ethoxyphenyl)-1-[2-(2-ethoxyphenyl)-4,5-diphenyl-2H-imidazol-2-yl]-4,5-diphenyl- 1 H-imidazole (LEDCIIR 110), 2,2',4-tri(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)- 4', 5'-diphenyl-1,1'-biimidazole (TCDM HABI).

[0194] The inhibitor (E) is present in the curable composition in particular in a proportion of 0.01 to 1.5 wt.%, based on the total weight of the composition, preferably in proportions of 0.1 to 1.5 wt.%.

[0195] The molar ratio of inhibitor (E) to first photoinitiator (C) in the curable composition is in particular in a range from 0.4:1 to 20:1, preferably in a range from 0.4:1 to 10:1 or 1:1 to 10:1, particularly preferably in a range from 1:1 to 5:1. The molar ratio of inhibitor (E) to second photoinitiator (D) in the curable composition can be 1:2 or less, preferably 1:5 or less, particularly preferably 1:10 or less.

[0196] Component (F): Additives

[0197] The compositions according to the invention may further contain optional components as additives (F).

[0198] The additives (F) are preferably selected from the group of fillers, dyes, photosensitizers, pigments, age inhibitors, fluorescent agents, accelerators (F1), adhesion promoters, drying agents, crosslinkers, flow improvers, wetting agents, thixotropic agents, diluents, non-reactive flexibilizers, non-reactive polymeric thickeners, flame retardants, corrosion inhibitors, plasticizers, tackifiers and combinations thereof.

[0199] Accelerator (F1):

[0200] In particular, in the case that the first curable component (A) contains a cationic polymerizable compound (A1), an accelerator (F1) for curing the mass by cationic polymerization may be added to the curable mass.

[0201] Peroxy compounds of the perester, diacyl peroxide, peroxydicarbonate, and / or hydroperoxide type can be used as accelerators (F1). Hydroperoxides are preferred. Cumene hydroperoxide in a 70 to 90% (v / v) solution in cumene is used as a particularly preferred accelerator.

[0202] By using peroxy compounds, the skin formation of the curable mass is accelerated after irradiation and activation of the first photoinitiator (C1) with the first wavelength i.

[0203] The proportion of peroxy compounds is selected such that sufficient open time remains for joining and optionally aligning a second substrate in the process according to the invention. The length of the required open time depends on the particular processing method being performed. The accelerator (F1), in particular the peroxy compound, is present in a proportion of 0 to 5 wt.%, based on the total weight of the composition.

[0204] The mass ratio between the first photoinitiator (C 1 ), for example ferrocenium hexafluoroantimonate, and the peroxy compound, for example cumene hydroperoxide, can be varied within wide limits. A mass ratio of 1:0.1 to 1:6 is preferably used, particularly preferably 1:2 to 1:4.

[0205] Formulation of the curable masses

[0206] A formulation of the compositions according to the invention, in particular for use in the process according to the invention, comprises at least the components (A) to (E) described above.

[0207] The mass preferably consists of the following components, each based on the total weight of the mass:

[0208] (A) 5 to 90 wt.% of the first curable component,

[0209] (B) 5 to 50 wt.% of the second curable component,

[0210] (C) 0.01 to 5 wt.% of the first photoinitiator,

[0211] (D) 0.01 to 5 wt.% of the second photoinitiator,

[0212] (E) 0.01 to 1.5 wt% of the inhibitor, and

[0213] (F) 0 to 80% by weight of additives.

[0214] The inhibitor is preferably selected from the group consisting of hindered phenols, thioethers, phosphites, hindered amines (HALS), optionally substituted styrenes, nitrous acid esters, alkyl nitrites, dithiocarbamates, and combinations thereof. More preferably, the inhibitor comprises 1,1-diphenylethylene, α-methylstyrene, tert-butyl nitrite, tetraethylthiuram disulfide, and 2,4-diphenyl-4-methyl-1-pentene, as well as combinations thereof.

[0215] According to a first embodiment, the composition preferably comprises or consists of the following components, in each case based on the total weight of the composition: (A) 10 to 85% by weight of a cationically polymerizable compound (A1) comprising at least one difunctional epoxide as the first curable component,

[0216] (B) 5 to 50 wt.% of at least one radically radiation-curable compound as a second curable component,

[0217] (0) 0.1 to 3 wt.% of a photolatent acid (C1) as the first photoinitiator,

[0218] (D) 0.5 to 3 wt.% of a radical photoinitiator as a second photoinitiator,

[0219] (E) 0.1 to 1.5 wt% of the inhibitor, and

[0220] (F) 0 to 80% by weight of additives.

[0221] According to a second embodiment, the mass preferably comprises or consists of the following components, each based on the total weight of the mass:

[0222] (A) 20 to 85 wt.% of an addition-crosslinkable compound (A2) comprising at least one at least difunctional isocyanate (A2-1) and one at least difunctional thiol (A2-2) as the first curable component,

[0223] (B) 5 to 50 wt.% of at least one radically radiation-curable compound as a second curable component,

[0224] (C) 0.1 to 3 wt.% of a photolatent base (C2) as the first photoinitiator,

[0225] (D) 1 to 5 wt.% of a radical photoinitiator as a second photoinitiator,

[0226] (E) 0.01 to 1.5 wt% of the inhibitor, and

[0227] (F) 0 to 80 wt.% of additives. The at least difunctional isocyanate (A2-1) may be completely or partially replaced by a hybrid compound of component (B) that carries radically radiation-curable groups together with isocyanate groups.

[0228] Suitable inhibitors (E) in the compositions of the second embodiment are particularly substituted styrenes, nitrous acid esters or alkyl nitrites and dithiocarbamates.

[0229] The compounds of the second embodiment form a polythiourethane network in the cured state. This network is characterized by high media resistance.

[0230] According to a third embodiment, the mass preferably comprises or consists of the following components, each based on the total weight of the mass:

[0231] (A) 15 to 85 wt.% of a moisture-crosslinkable compound (A3) comprising at least one silane as the first curable component,

[0232] (B) 5 to 50 wt.% of at least one radically radiation-curable compound as a second curable component,

[0233] (C) 0.05 to 3 wt.% of a photolatent acid (01) as the first photoinitiator,

[0234] (D) 0.1 to 3 wt.% of a radical photoinitiator as a second photoinitiator,

[0235] (E) 0.01 to 1.5 wt% of the inhibitor, and

[0236] (F) 0 to 80% by weight of additives.

[0237] The compositions according to the invention of all embodiments are preferably provided as one-component compositions.

[0238] Use of the hardenable mass

[0239] The curable compound described above is particularly suitable for joining, encapsulating, or coating substrates. This also includes bonding, molding, or sealing substrates. These curable compounds are particularly suitable for applications in which strength buildup is to be specifically controlled by light fixation while simultaneously ensuring reliable curing in shadow zones, especially in the case of non-transmissible substrates. This property profile is particularly required in the production of electro-optical components such as camera modules, the joining of displays, or encapsulations with complex geometries, such as sensor encapsulations.

[0240] Housing bonding or application in fuel cells are also conceivable with the masses described above, in particular when using cationically polymerizable compounds (A1) with 1,1-diphenylethylene, tert-butyl nitrite and / or 2,4-diphenyl-4-methyl-1-pentene as inhibitor (E).

[0241] According to one embodiment of the method according to the invention, the masses can be activated by irradiation with the first wavelength Ai in a flow-through process. This means that the liquid mass is irradiated with actinic radiation, for example, during dispensing before leaving the dispensing device and is thereby activated. Dispensing devices that have a transmissible zone and suitable LED irradiation devices are commercially available from DELO Industrie Klebstoffe GmbH & Co. KGaA under the trade name DELO-ACTIVIS and are described, for example, in DE 10 2021 133 731 A1. The use of such a flow-through activation device offers the advantage that dispensing and activation of the mass can take place in a single process step. This reduces the equipment required and saves installation space in industrial plants.

[0242] The dosing pressure of the mass in a flow-through activation device is preferably 15 bar or less. The dosing pressure is particularly preferably below 10 bar to ensure process-safe and reliable activation of the mass. Typical dosing rates have volume flows of 1 to 15 cm 3 / min, preferably 2 to 10 cm 3 / min. Dosing rates that are too low can lead to premature curing within the apparatus. Dosing rates that are too high can lead to incomplete activation of the material at a given irradiation power.

[0243] After activation of the mass by actinic radiation at the first wavelength Ai, it exhibits an open time during which the activated mass remains liquid and does not yet exceed the gel point. Within this open time, the subsequent process steps, in particular the feeding and joining of another substrate (step c), can be carried out reliably.

[0244] However, it is also possible for the activated mass to remain at least partially joinable beyond the specified open time before solidifying to such an extent that no further flow or pressing onto another substrate is possible. To enable a robust process, however, the addition of a second substrate in step c) of the method according to the invention, if carried out, is preferred within the open time.

[0245] The open time of the activated masses is preferably at least 0.1 minute, and up to 30 minutes, more preferably up to 15 minutes or up to 5 minutes. Shorter open times of 0.1 to 1 minute are particularly suitable for rapid industrial manufacturing processes. When using a flow-through activation apparatus, however, a longer open time may be advantageous for reasons of process reliability, in particular an open time of 1 minute or more, preferably an open time in the range of more than 5 to 30 minutes.

[0246] There is usually a correlation between the open time and the curing time, i.e. a shorter open time is not advantageous per se but can offer advantages for the overall process due to the faster curing of the mass.

[0247] However, curable materials with very short open times of less than one minute can only be processed to a limited extent in a joining process after activation and are also not suitable for flow activation.

[0248] After fixation by actinic radiation with the second wavelength λ2, the compound has at least a so-called "green strength" or handling strength. This means that no further flow occurs after fixation. Components in joints remain fixed relative to one another and can thus be fed to further production steps, for example, even manually. The compound activated and fixed by the process according to the invention typically cures completely within 7 days at room temperature, preferably within 3 days, particularly preferably within one day, i.e. within 24 hours. For faster curing or to accelerate the final curing of the compound, the compound can be heated either during or after the light fixation in step d).

[0249] Measurement methods and definitions used

[0250] Irradiation

[0251] To activate the curable compound with actinic radiation of the first wavelength Ai and to fix it with actinic radiation of the second wavelength Ä2, the compounds were each irradiated with a DELOLUX 20 LED lamp from DELO Industrie Klebstoffe GmbH & Co. KGaA. Different lamps were used for different wavelengths. The respective exposure times, intensities, and wavelengths can be found in the following tables for the test examples.

[0252] Room temperature

[0253] Room temperature is defined as 23 ± 2 °C.

[0254] Curing

[0255] "Crosslinking" or "curing" is defined as a polymerization reaction beyond the gel point. The gel point is the point at which the storage modulus G' becomes equal to the loss modulus G".

[0256] Open time

[0257] The determination is carried out using a haptic test using a toothpick on adhesive drops (10 mg) on ​​a glass slide. A triplicate determination is performed, and the arithmetic mean of the measured values ​​obtained provides the open time. The adhesive drops are activated with an LED floodlight (DELOLUX 20) under predefined conditions depending on the intended application. The activation conditions, such as intensity, duration, and wavelength of the irradiation, can be found in the following tables for the test examples. A stopwatch is started at the end of the irradiation.

[0258] Using the toothpick, the expected viscosity increase is assessed haptically compared to a non-activated reference sample of the same size and geometry. At intervals of approximately 5 s, the geometry of the activated adhesive droplet is manipulated with the toothpick in a vertical movement by pulling the tip of the toothpick upward from the center of the adhesive droplet, holding the toothpick at an angle of approximately 45° to the slide. If the activated adhesive droplet does not return to its original geometry within 1 s of manipulation with the tip of the toothpick, the stopwatch is stopped, and the end of the adhesive's open time is reached.

[0259] If a mass remains liquid or has an open time of less than 0.1 min and can no longer be reliably determined using the described method, it is marked as undetermined with "nb".

[0260] Assessment of light fixation

[0261] To assess light fixation (solid vs. liquid), the compound is subjected to a visual assessment after irradiation with actinic radiation of the second wavelength λ2. The intensity, duration, and wavelength of the irradiation can be found in the tables below for the test examples. Optionally, a tactile test is performed using a plastic spatula.

[0262] Masses that exhibit a skin after irradiation and no longer flow are classified as "yes" with regard to their light fixation. Masses that exhibit no skin after irradiation or that continue to flow are classified as "no" with regard to their light fixation.

[0263] Photo DSC measurements

[0264] DSC measurements of the reactivity of radiation-induced curing are performed in a Mettler Toledo DSC3+ differential scanning calorimeter (DSC). For this purpose, 6 to 10 mg of the liquid sample is weighed into an open aluminum crucible (40 pL) and irradiated at 30 °C for 5 minutes. The intensity and wavelength can be found in the tables below for the test examples.

[0265] The peak time is evaluated after subtracting the energy input caused by the LED lamp.

[0266] Production of the hardenable masses

[0267] To produce the curable masses used in the following examples, the liquid and soluble components are first mixed and then the fillers and optionally other solids are incorporated using a laboratory stirrer, laboratory dissolver or a speed mixer (Hauschild) until a homogeneous mass is formed.

[0268] Masses containing photoinitiators that are sensitive to visible light must be prepared under light outside the excitation wavelength of the respective photoinitiators or sensitizers.

[0269] The following list shows all the compounds used to produce the curable masses and their abbreviations:

[0270] Component (A): First curable component

[0271] (A1) Cationically polymerizable compounds:

[0272] (A1-1): Epikote™ Resin 169 (mixture of bisphenol A and bisphenol F glycidyl ethers, available from Hexion)

[0273] (A1-2): 3,4-Epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, available under the trade name Celloxide 2021 P from Daicel

[0274] (A1-3): Eternacoll UM 90 (1 / 1) (aliphatic polycarbonate diol), available from UBE Industries Ltd.

[0275] (A1-4): Bis[1-Ethyl(3-oxetanyl)]methyl ether], available from DKSH

[0276] (A2) Addition-crosslinkable compounds:

[0277] (A2-1): Isocyanates (A2-1-1): Desmodur Ultra N3600 Aliphatic polyisocyanate (HDI isocyanurate), available from Covestro

[0278] (A2-2) Thiols

[0279] (A2-2-1): Tris(3-mercaptopropyl)isocyanurate (trifunctional thiol)

[0280] (A3) Moisture-crosslinkable compounds

[0281] (A3-1): Geniosil STP-E15; at least difunctional γ-alkoxysilane compound, available from Wacker

[0282] (A3-2): Dynasylan VTMO; monofunctional y-alkoxysilane compound, available from Evonik

[0283] Component (B): Second curable component

[0284] (B-1): Sartomer SR833S (tricyclodecanedimethanol diacrylate), available from Sartomer

[0285] (B-2): Photomer 4006 (trimethylolpropane triacrylate), available from iGM Resins

[0286] (B-3): Epoxy Acrylate Solmer E 1605, available from Solmer Soltech Ltd.

[0287] (B-4): Taicros® (triallyl isocyanurate), available from Evonik

[0288] (B-5): Laromer PR9000 (hybrid compound isocyanate and acrylate), available from BASF SE

[0289] Component (C): Initiator for the first wavelength Ai

[0290] (C-1): R-Gene 262 (n 5-2,4-cyclopentadien-1-yl)[(1,2,3,4,5,6- )-(1-methylbenzyl)benzene]-iron(l) hexafluoroantimonate; 50% in propylene carbonate, available from Chitec Technology

[0291] (C-2): CGI-277 (2-benzyl-1-(3,5-dimethoxyphenyl)-2-(dimethylamino)butan-1-one), available from BASF

[0292] (D-1): Omnirad BDK (2,2-dimethoxy-1,2-diphenylethan-1-one), available from IGM Resins

[0293] (D-2): Omnirad 184 (l-hydroxycyclohexyl)phenylmethanone), available from IGM Resins

[0294] (D-3) Omnirad 127 D (1,1'-(Methylene-di-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propanone]), available from IGM Resins

[0295] Component E: Inhibitors

[0296] (E-1): Nofmer MSD (1,1'-(1,1-dimethyl-3-methylene-1,3-propanediyl)bisbenzene), available from NOF Corporation

[0297] (E-2):1,1-Diphenylethylene, available from TCI Germany

[0298] (E-3): tert-butyl nitrite > 90%, available from Merck

[0299] (E-4): 2,6-Di-tert-butyl-4-methylphenol >99%, available from Merck

[0300] Component F: Additives

[0301] (F-1): Trigonox K-90 (cumene hydroperoxide 90%, other ingredients: 2-phenylisopropanol, cumene, acetophenone), available from AkzoNobel

[0302] (F-2): Dodecylbenzenesulfonic acid > 95%, available from TCI

[0303] (F-3): Trioctyl trimellitate Oxsoft TOTM LE, available from Krahn

[0304] (F-4) Bluesil Photoinitiator 2074 (4-(-1-Methylethyl)phenyl)-(4-methylphenyl)iodonium tetrakis(pentafluorophenylborate), available from Bluestar Silicones

[0305] The compositions of the respective curable masses are listed in Tables 1 to 3 below. All weight proportions listed below refer to the total weight of the curable masses. Table 1: Examples according to the first embodiment.

[0306]

[0307]

[0308] *: Comparison example

[0309] Table 2: Examples according to the second embodiment.

[0310]

[0311]

[0312]

[0313] *: Comparison example

[0314] Table 3: Examples according to the third embodiment.

[0315]

[0316]

[0317]

[0318] *: Comparison example

[0319] Examples E1 to E7 in Table 1 show compositions of the first embodiment based on at least one cationically polymerizable compound (A1) for use in the process according to the invention. The compositions contain a photolatent acid (C-1) as the first photoinitiator (C) for the first curable component (A).

[0320] The activated masses of examples E1 to E6 initially remain liquid after irradiation with light of the first wavelength Ai and have open times in the range of 1.5 to 22 minutes. They are therefore suitable for pre-activation. In particular, masses with a longer open time, such as example E6, can be used reliably in a flow-through activation apparatus. Shorter open times are suitable for bonding processes in which components are joined within a short period of time. Even if no fixing by irradiation with light of the second wavelength A2 according to step d) of the described process takes place, the masses become solid and cure after 24 hours at the latest. Conversely, this means that the masses of examples E1 to E7 are suitable for reliable curing after activation with light of the first wavelength Ai, even in shadow zones that are not accessible to irradiation with light of the second wavelength A2 in step d).

[0321] Furthermore, all examples E1 to E7 can be fixed by irradiation with light of the second wavelength A2. During the open time, the viscosity of the compositions is preferably at most 500 Pas.

[0322] Different open times can be adjusted by the proportion of inhibitor (E) or the molar ratio of inhibitor (E) to the first photoinitiator (C), which can be activated upon irradiation with the first wavelength Ai. For example, a smaller proportion of inhibitor (E) with a molar ratio of components (E) to (C) reduced by a factor of 7 in Example E7 leads to an open time of 1 minute, in direct comparison to an otherwise analogous formulation according to Example E2. However, fixing of the composition according to Example E7 after irradiation with light of the second wavelength A2 remains possible, since there is an excess of second photoinitiator (D) with respect to inhibitor (E), which can be activated upon irradiation with light of the second wavelength A2. Comparative Example C3 has a high proportion of inhibitor (E) of over 1.5% by weight.-% with a molar ratio of inhibitor (E) to first photoinitiator (C) of 23.5:1. The mass cannot be activated by irradiation with light of the first wavelength Ai under the selected conditions, but remains liquid even after 24 hours. Light fixation by irradiating the mass with light of wavelength A2 also fails under the conditions of Comparative Example C3.

[0323] Example E3 demonstrates the use of an alternative inhibitor (E-2). With the same molar ratio of (E) to (D) and (E) to (C) compared to Example E2, a similar open time can be achieved after activation by irradiation with the first wavelength Ai.

[0324] In contrast to Examples E1 to E4 based on a glycidyl ether, Example E5 shows a formulation using an alternative resin system comprising a cycloaliphatic epoxide and a polyol. This composition can also be advantageously used in the process according to the invention.

[0325] Comparative Example V1 shows a formulation based on the prior art according to EP 3 894 458 B1. The composition contains no inhibitor (E) and solidifies immediately upon irradiation with light of the first wavelength Ai and is therefore unsuitable for use in the process according to the invention due to the lack of an open time.

[0326] In contrast, the composition according to Example E6, which is comparable to the composition of Comparative Example C1 and additionally contains an inhibitor (E-1) based on a methylstyrene dimer, can be activated by irradiation with light of the first wavelength A1 without the composition immediately solidifying. After activation, the composition has an open time of 22 minutes and can be fixed by irradiation with light of the second wavelength A2.

[0327] The process according to the invention can be carried out independently of the resin system used and can be achieved solely by the addition of the inhibitor (E). Thus, the composition according to Comparative Example C2, which contains a cationically polymerizable compound based on a glycidyl ether (A1-1), does not exhibit a sufficient open time within the meaning of the invention in the absence of component (E). The comparable composition of Example E3, on the other hand, is activatable, has an open time of approximately 10 minutes, and can be fixed in a further step by irradiation with light of the second wavelength A2. The proportion of the inhibitor (E) in the curable composition is selected depending on the amount of photoinitiator (C) and the irradiation dose such that curing of the activated composition can occur within 24 hours.

[0328] Examples E8 to E13 in Table 2 show compositions of the second embodiment based on at least one addition-crosslinkable compound (A2) for use in the process according to the invention. The compositions contain a photolatent base (C-2) as the first photoinitiator (C) for the first curable component (A).

[0329] The second curable component (B) used in the compositions of the second embodiment includes, for example, acrylates (B-2; Example E11), allyl compounds (B-4; Example E8), or hybrid compounds comprising acrylate and isocyanate functionality (B-5; Example E13). The hybrid compound (B-5) can completely or partially replace the isocyanate compound of component (A2). All of the substance classes mentioned can be fixed by irradiation with light of the second wavelength A2.

[0330] Examples E8 to E13 are suitable for carrying out the process according to the invention and, after activation by irradiation with light of the first wavelength Ai, cure reliably even in shadow zones.

[0331] The masses have open times of 1.5 to 3.5 minutes and can be fixed by irradiation with light of the second wavelength A2.

[0332] Comparative example V4 omits the first photoinitiator (C). Although the compound can be fixed by irradiation with light of the second wavelength A2, it cannot be activated. This means that after irradiation with light of the first wavelength Ai, the compound remains liquid even after 24 hours and has no measurable open time. It is therefore unsuitable for curing in shadowy areas.

[0333] If, however, the second photoinitiator (D) is omitted, as in Comparative Example V5, the compositions cure after 24 hours after irradiation with light of the first wavelength Ai without any further energy input. However, fixation according to step d) of the process according to the invention is not possible. Omitting the inhibitor (E), as shown in Comparative Example V6, results in compositions that have no open time and solidify immediately after irradiation with light of the first wavelength Ai.

[0334] The composition of Comparative Example V7 has a high proportion of inhibitor (E) of over 1.5 wt.%. However, such a high proportion of inhibitor (E), based on the total weight of the composition, can lead to compositions that are no longer activatable in accordance with the invention, even if the molar ratio of inhibitor (E) to first photoinitiator (C) is within a range otherwise suitable for carrying out the process according to the invention.

[0335] Example E14 in Table 3 shows a composition of the third embodiment based on at least one moisture-crosslinkable compound (A3) comprising a γ-alkoxysilane compound. The composition of Example E14 has a proportion of inhibitor (E) of 0.37 wt. % with a molar ratio of inhibitor (E) to first photoinitiator (C) of 3:1. The molar ratio of inhibitor (E) to second photoinitiator (D) is 1:6. The composition can be activated by irradiation with light of the first wavelength A1 and fixed by irradiation with light of the second wavelength A2. The open time after the first irradiation is 12 minutes. The composition is suitable for use in the process according to the invention.

[0336] Comparative Example V8, on the other hand, dispenses with the addition of an inhibitor (E). Without the addition of component (E), a stepwise implementation of the process and control of the strength buildup cannot be ensured. Irradiation with light of the first wavelength A1 as well as with light of the second wavelength A2 directly leads to solidification of the composition. The composition of Comparative Example V8 is therefore not suitable for use in the process according to the invention.

[0337] The cured masses of all described embodiments of the invention achieve a compressive shear strength of at least 1 MPa on aluminum after their final curing.

Claims

Patent claims 1. A method for joining, casting or coating substrates using a curable mass, the method comprising the following steps: a) providing the curable mass, the curable mass comprising the following components: (A) a first curable component selected from the group consisting of cationically polymerizable compounds, addition-curable compounds, moisture-curable compounds, and combinations thereof, (B) a second curable component consisting of at least one radically radiation-curable compound, (C) a first photoinitiator for the first curable component (A) which is activatable upon irradiation with actinic radiation of a first wavelength Ai, wherein the first photoinitiator is a photolatent acid or a photolatent base, (D) a second photoinitiator for the second curable component (B) which is activatable upon irradiation with actinic radiation of a second wavelength A2, wherein the second wavelength A2 is different from the first wavelength Ai, and wherein the second photoinitiator is a free radical former, and (E) at least one radical-scavenging inhibitor for scavenging radicals generated upon irradiation of the curable composition with actinic radiation of the first wavelength Ai; b) dosing the curable composition onto a first substrate and activating the curable composition by irradiation with actinic radiation of the first wavelength A; c) optionally adding a second substrate to the activated curable composition on the first substrate to form a substrate composite; and d) Fixing the activated curable mass by irradiation with actinic radiation of the second wavelength A2.

2. The method of claim 1, wherein the second wavelength A2 is shorter than the first wavelength Ai.

3. The method according to claim 1 or 2, wherein steps b) to d) are carried out within a processing time which corresponds at most to an open time of the curable composition after activation of the curable composition by irradiation with actinic radiation of the first wavelength Ai.

4. Process according to one of the preceding claims, wherein the inhibitor (E) is present in a proportion of 0.01 to 1.5 wt.%, based on the total weight of the composition.

5. The method according to any one of the preceding claims, wherein a molar ratio of inhibitor (E) to the first photoinitiator (C) in the curable composition is in a range from 0.4:1 to 20:

1.

6. The method according to any one of the preceding claims, wherein a molar ratio of inhibitor (E) to second photoinitiator (D) in the curable composition is less than 1:

2.

7. Method according to one of the preceding claims, wherein the activation of the curable composition is carried out by irradiation with actinic radiation of the first wavelength Ai in the flow.

8. The method according to any one of the preceding claims, wherein the method further comprises the following step: e) heating the fixed curable mass on the first substrate or in the substrate composite.

9. Curable compound for joining, casting or coating substrates, the curable compound comprising the following components: (A) a first curable component selected from the group consisting of cationically polymerizable compounds, addition-curable compounds, moisture-curable compounds, and combinations thereof, (B) a second curable component consisting of at least one radically radiation-curable compound, (C) a first photoinitiator for the first curable component (A) which is activatable upon irradiation with actinic radiation of a first wavelength Ai, wherein the first photoinitiator is a photolatent acid or a photolatent base, (D) a second photoinitiator for the second curable component (B) which is activatable upon irradiation with actinic radiation of a second wavelength X2, wherein the second wavelength X2 is different from the first wavelength Ai, and wherein the second photoinitiator is a free radical former, and (E) at least one radical-scavenging inhibitor for scavenging radicals generated upon irradiation of the curable composition with actinic radiation of the first wavelength Ai.

10. Curable composition according to claim 9, wherein the curable composition consists of the following components, each based on the total weight of the composition: (A) 5 to 90 wt.% of the first curable component, (B) 5 to 50 wt.% of the second curable component, (C) 0.01 to 5 wt.% of the first photoinitiator, (D) 0.01 to 5 wt.% of the second photoinitiator, (E) 0.01 to 1.5 wt% of the inhibitor, and (F) 0 to 80% by weight of additives.

11. Use of the curable composition according to claim 9 or 10 for joining, casting or coating substrates.

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