Curable compositions, methods for joining, coating or casting substrates and uses of the compositions

Abstract

The invention relates to a composition which is fixable by actinic radiation and which is heat-curable, comprising (A) at least difunctional, blocked solid isocyanate; (B) an isocyanate-reactive component comprising at least one liquid hybrid compound (B1) which, in addition to containing at least one isocyanate-reactive group, also contains at least one free-radically curable group, the hybrid compound (B1) having a molar mass of at least 400 g / mol; and (C) an initiator system for free-radical polymerization comprising a first initiator (C1) which is a free-radical photoinitiator and a second initiator (C2) which is a free-radical initiator for heat curing. The invention also relates to a process for bonding, casting and / or coating substrates and to the use of the curable composition.

Description

Technical Field

[0001] This invention relates to one-component compositions based on polyisocyanates, which can be fixed by photochemical radiation and can be cured by heat.

[0002] Furthermore, the present invention relates to a method of using the composition for bonding, coating or casting a substrate, and the use of the composition for bonding, casting and / or adhesiveling electronic and optoelectronic components. Background Technology

[0003] Thermosetting compositions based on polyisocyanates and polyamines or polyols are generally known. To ensure sufficient storage stability, solid isocyanates can be used, which are passivated on their surface and exist in a dispersed form within a higher molecular weight isocyanate reactive component. When heat is supplied, the surface-passivated polyisocyanate melts and the adhesive cures. The cured composition is characterized by silicone-like mechanical properties. These include a low glass transition temperature and high flexibility and durability. These property characteristics are advantageous for applications in bonding chips, sensors, speakers, and cameras.

[0004] Additional radiation-curing components enable rapid fixation of the composition and joints, achieving a final curing that is spatially and temporally decoupled. This allows for the rapid fixation of complex geometries and the production of larger quantities per unit time. However, additional radiation-curing components also introduce technical drawbacks, as they may dissolve surface-passivated polyisocyanates and impair the storage stability of the composition. Furthermore, uncured components of the radiation-curable network remain in the shaded areas, adversely affecting the performance of the cured adhesive.

[0005] Suitable curing agents for polyisocyanate formulations include amines, alcohols, or thiols. Liquid compounds with higher molecular weights containing the above functional groups (e.g., based on polyolefins, polyesters, or polyethers) are often used as dispersion media.

[0006] The synthesis of polyether amines is well known, as described, for example, in US 3 654 370 A or US 5 103 062 A. Here, the terminal hydroxyl groups of the polyether polyol typically react to form the corresponding amine.

[0007] WO 2020 250 154 A1 describes (meth)acrylate-functionalized crosslinking agents for structural bonding. The polyether polyols and polyether polyamines used in their production are, among other things, fully reacted with isocyanate-based (meth)acrylates to form polyurethane and polyurea compounds before being incorporated into adhesive formulations.

[0008] WO 2021 090 216 A1 describes hydrophilic (meth)acrylate-functionalized monomers based on polyetheramines. These are completely converted to secondary and / or tertiary amines via Michael addition reactions with polyfunctional (meth)acrylates. Use as hybrid reactive compounds is not described.

[0009] WO 2012 121 822 A1 describes the use of (meth)acrylates in the synthesis of hybrid polyamines and their use as curing agents for epoxy resins. Here, (meth)acrylates are used for chain extension of polyetheramines and polyalkyleneamines.

[0010] WO 2008 076 662 A2 uses monofunctional (meth)acrylates and amines, as well as (meth)acrylates and amines with higher functionality, to produce oligomers with defined reactivity to isocyanates. During the reaction, the (meth)acrylate component is consumed, yielding a product primarily containing secondary amines. The binder is formulated as a two-component composition. No additional fixation or curing by light is provided.

[0011] Polyetheramines and their blends can also be used as curing agents for epoxy resins, as described in WO 2018 144 974 A1.

[0012] EP 0 103 323 B1 describes a method for preparing a surface-passivated solid polyisocyanate and its use in a storage-stable and thermosetting composition. Higher molecular weight polyols and / or polyamine compounds and lower molecular weight chain extenders are described as curing agents. Optionally, additional components containing the aforementioned functional groups may be added.

[0013] EP 0 100 508 B1 describes a thermosetting composition based on a polyisocyanate. During the surface passivation of the solid polyisocyanate, a long-chain polyetheramine is used as a liquid medium. During thermosetting, these subsequently react into the polymer network.

[0014] EP 3 749 700 A1 discloses a single-component, storage-stable composition based on a surface-passivated polyisocyanate. This composition can be fixed by light by adding a radical-curable radiation-curable component and a photoinitiator. Further, the use of hybrid compounds is proposed, which, in addition to having radiation-curable groups, possess additional isocyanate reactive groups to link networks formed by photocuring and thermal curing. Disadvantages of these compositions include low light-fixing strength and poor adhesion, attributed to incomplete crosslinking of the radical-polymerizable component in shaded regions. Summary of the Invention

[0015] The purpose of this invention is to avoid the disadvantages of known compositions in the prior art and to provide curable compositions, particularly single-component compositions based on polyisocyanates, characterized by their high gloss setting strength and reliable curing in shaded areas.

[0016] According to the invention, this objective is achieved by the composition according to claim 1. Advantageous embodiments are specified in the dependent claims, which may optionally be combined with each other.

[0017] The composition according to the invention is photocurable and thermocurable, the composition comprising:

[0018] (A) At least a bifunctional, passivated solid isocyanate,

[0019] (B) An isocyanate reactive component comprising at least one liquid hybrid compound, which, in addition to containing at least one isocyanate reactive group, also contains at least one radical-curable group, wherein the molar mass of the hybrid compound is at least 400 g / mol, and

[0020] (C) An initiator system for free radical polymerization, comprising a first initiator and a second initiator, wherein the first initiator is a free radical photoinitiator and the second initiator is a free radical initiator for thermosetting.

[0021] This curable composition is liquid at room temperature and, after curing, is characterized by high elongation at break and temperature stability. Specifically, the cured composition has an elastic modulus in the range of 5 MPa to 500 MPa, which remains substantially constant over a temperature range of -35°C to 100°C. This is also attributed to the fact that the glass transition temperature of the cured composition is typically -40°C or lower. Therefore, the composition according to the invention is also suitable for applications where significant temperature fluctuations are anticipated.

[0022] Unless otherwise stated, molar mass here and below refers to the average molar mass M. n .

[0023] The use of hybrid compounds connects the networks formed by photocuring and thermocuring (hereinafter also referred to as "light networks" and "shadow networks"). In addition to the isocyanate reactive groups, the hybrid compounds also have at least one radical-curable group, which enables the curable composition to be photo-fixed. An additional radical initiator for thermocuring allows the radical-curable group to be fully cured in the shadowed areas, resulting in uniform properties of the cured composition throughout the application area.

[0024] Additional radical-curable monomers, optionally incorporated into the composition and lacking isocyanate reactive groups, can also advantageously increase photo-fixing strength due to the addition of a radical initiator for thermosetting, as these are reliably incorporated into the polymer network in the shaded areas during the thermosetting step following photosetting. Without the addition of a radical initiator for thermosetting, uncrosslinked formulation components will remain in the shaded areas, leading to reduced adhesion and undesirable gas release from the cured composition.

[0025] The combination of isocyanate reactive groups and radical-curing groups in a single molecule often results in a lack of sufficient storage stability or processing time for the component. Surprisingly, it has now been found that advantageous combinations of radical-curing groups and isocyanate reactive groups can be achieved in hybrid molecules, enabling the coupling of light and shadow networks while maintaining high adhesion. Furthermore, sufficiently high photocuring intensity can be achieved by reducing the amount of further radical photocuring components or by omitting them entirely.

[0026] Therefore, the curable compositions according to the invention are particularly suitable for applications in which the advantageous properties of the cured composition, combined with high gloss setting strength, can be advantageously utilized. This performance characteristic is advantageous, for example, for bonding chips, sensors, or speakers.

[0027] Surprisingly, due to its combination with free radical curable formulation components, it can counteract the volume changes, particularly volume expansion, during the curing process of isocyanate components, thereby enabling the production of adhesives with low expansion or even shrinkage (i.e., volume reduction). This property is particularly advantageous in optical applications, such as the fabrication of LIDAR components or the bonding of lenses or optoelectronic components (such as camera modules).

[0028] The present invention further relates to methods for bonding, coating and / or casting substrates using curable compositions according to the invention.

[0029] The corresponding methods for bonding, casting, and / or coating substrates using the curable composition according to the invention as described above include the following steps:

[0030] (a) Applying the curable composition to a first substrate;

[0031] (b) Optionally, a second substrate is provided to form a substrate composite;

[0032] (c) Fixing the curable composition with photochemical radiation; and

[0033] (d) The fixed composition on or in a substrate composite is thermocured by heating to a temperature of at least 60°C.

[0034] Photocurability enables curable compositions to transition to a dimensionally stable state and to be ultimately cured by heat in time-decoupled subsequent process steps.

[0035] By controlling the volume change, the method using the composition according to the invention also enables reliable light fixation and curing even for particularly challenging geometries, such as in optical applications, without introducing undesirable stress.

[0036] The object of the present invention is further achieved by using the curable composition to bond, cast, and / or adhere electronic and optoelectronic components used in the manufacture of camera modules or LIDAR systems. Detailed Implementation

[0037] The present invention will now be described in detail by way of example with reference to preferred embodiments; however, it should not be construed as limiting. The following definitions are used in this specification:

[0038] Within the meaning of this invention, "single-component" or "single-component composition" means that the components of the composition are present together in a single packaging unit. Therefore, the components of the composition are not stored separately from each other.

[0039] The composition is considered "processable" if the viscosity of each fully mixed composition increases by less than 25% during storage at room temperature for at least 72 hours.

[0040] Within the meaning of this invention, "liquid" means a loss modulus G'' measured by rheological measurements at 23°C that is greater than the storage modulus G' of the composition under discussion.

[0041] "Cure" is defined as a polymerization reaction that exceeds the gel point. The gel point is the point where the storage modulus G' equals the loss modulus G''.

[0042] "At least bifunctional" means that the corresponding compound or mixture of substances has a functionality of at least 2 based on a specific functional group or several specific functional groups. Therefore, at least bifunctional isocyanates contain at least two isocyanate groups (-NCO) in their molecules.

[0043] "Fixing" refers to the formation of sufficient strength in a composition to prevent further flow, or to a level of strength at which bonded components, particularly substrates, can be processed in subsequent processes without damaging the adhesive compound, particularly the substrate compound.

[0044] A "primary amine" is an amine that exists only bonded to one other hydrocarbon unit. In contrast, a "primary alcohol" or "primary thiol" refers to an amine whose functional group is bonded to a primary carbon atom. A "primary carbon" refers to a carbon atom that exists only bonded to one additional hydrocarbon unit. Similar definitions apply to secondary and tertiary functional groups.

[0045] When the indefinite articles “a” or “an” are used, this also includes the plural forms “one or more”, unless explicitly excluded.

[0046] Unless otherwise stated, all weight percentages listed below refer to the total weight of the curable composition.

[0047] The components of the curable composition according to the invention, which can be used particularly in the method according to the invention, will be described in more detail below.

[0048] Component (A): Passivated solid isocyanate

[0049] At least bifunctional, passivated solid isocyanate (A) is an isocyanate obtained by reacting at least bifunctional solid isocyanate (A1) (hereinafter also referred to as polyisocyanate (A1)) with a passivating agent (A2).

[0050] Polyisocyanates (A1)

[0051] To provide a storage-stable composition, the solid polyisocyanate (A1) is appropriately passivated on its surface. For this purpose, the solid polyisocyanate (A1) reacts on its surface with a passivating agent (A2). Passivation prevents the isocyanate (A1) from reacting with other isocyanate reactive formulation components, or slows the reaction to a degree sufficient to ensure adequate processing time and storage stability.

[0052] In principle, any at least bifunctional isocyanate with a melting point, particularly at least 40°C, can be used as a polyisocyanate (A1). Preferably, the polyisocyanate (A1) has a melting point of at least 60°C. Preferably, the melting point of the solid polyisocyanate is at most 200°C, and particularly preferably at most 180°C.

[0053] The polyisocyanate (A1) is preferably an aliphatic, alicyclic, heterocyclic, or aromatic polyisocyanate. The polyisocyanate (A1) may exist at least partially, preferably completely, in a dimer (ureidone form) or trimer (isocyanurate form). Examples of suitable polyisocyanates (A1) include: dimerized 2,4-diisocyanatotoluene, dimerized 4,4'-diisocyanatodiphenylmethane, 3,3'-diisocyanato-4,4'-dimethyl-N,N'-diphenylurea, isocyanurates of isophorone diisocyanates, 1,4-phenylene diisocyanate, naphthalene-1,5-diisocyanate, and addition products of diisocyanates with short-chain diols having 2 to 6 carbon atoms (e.g., 1,4-butanediol or 1,2-ethylenediol). Particularly preferred are isocyanurates of dimeric 2,4-diisocyanotoluene, dimeric 4,4'-diisocyanodiphenylmethane, 3,3'-diisocyano-4,4'-dimethyl-N,N'-diphenylurea, and / or isophorone diisocyanate.

[0054] Preferably, the solid polyisocyanate (A1) exists in particulate form, with a volumetric particle diameter d95 of up to 100 µm, more preferably up to 40 µm, and particularly preferably up to 10 µm.

[0055] Passivating agent (A2)

[0056] Preferably, the solid polyisocyanate (A1) is reacted on its surface with a passivating agent (A2), as described in EP 0 153 579 A2, EP 0 100 508 B1 or EP 3 749 700 A1.

[0057] A substantially inert shell is formed on the surface of the solid polyisocyanate (A1) by reacting it with a passivating agent (A2), which prevents further reaction of the isocyanate groups located beneath the shell until the shell is decomposed by supplying heat during a subsequent thermosetting step, thereby curing the composition (especially a one-component composition).

[0058] The preferred passivating agent (A2) is a compound derived from the group consisting of polyamines, amidine and / or guanidine compounds, hydrazines, alkyl hydrazines and / or acyl hydrazines, which reacts with isocyanate groups present on the surface of the solid polyisocyanate (A1) to form urea groups.

[0059] Particularly preferred is the use of at least a bifunctional aliphatic primary amine with a molecular weight in the range of 60 g / mol to 600 g / mol as the passivating agent (A2), particularly preferred are polyetheramines, such as those commercially available, such as those from Huntsman under the trade names Jeffamine® D-400 or Jeffamine® T-403.

[0060] For passivation, 0.1 to 25 mol percent (preferably 0.5 to 15 mol percent, particularly preferably 1 to 10 mol percent) of all isocyanate groups present in the solid polyisocyanate (A1) can be reacted with the passivating agent (A2).

[0061] In a preferred embodiment, at least bifunctional, passivated solid isocyanate (A) is obtained by reacting the solid polyisocyanate (A1) in particulate form with a passivating agent (A2) in a liquid medium at a temperature below the melting point of the solid polyisocyanate (A1), wherein the liquid medium itself is not a good solvent for the solid polyisocyanate (A1). Higher molecular weight polyols or polyamines with a molecular weight of up to 20,000 g / mol (which themselves can be used as the isocyanate reactive component (B) in the curable composition according to the invention) can be used as the liquid medium. In this case, the reactivity of the liquid medium and the passivating agent (A2) is selected such that the reaction with the passivating agent (A2) occurs substantially on the surface of the solid polyisocyanate (A1).

[0062] According to a preferred embodiment, the surface-passivated solid isocyanate (A) is present in a dispersed form. This allows for the production of a particularly uniformly cured composition upon supply of heat.

[0063] Preferably, the solid polyisocyanate (Al) exists in particulate form with a volumetric particle diameter d95 of up to 100 µm, more preferably up to 40 µm, and particularly preferably up to 10 µm. Particles of this size are also referred to as micronized particles.

[0064] According to a further aspect of the invention, based on the total weight of the curable composition, the composition contains a proportion of 1 wt.% to 40 wt.% (preferably 4 wt.% to 20 wt.%) of passivated solid isocyanate (A).

[0065] Component (B): Isocyanate reactive component

[0066] In addition to at least a bifunctional, passivated solid isocyanate (A), the curable composition according to the invention also contains an isocyanate reactive component (B).

[0067] Hybrid compound (B1)

[0068] According to the present invention, component (B) comprises at least one liquid hybrid compound (B1) which, in addition to containing isocyanate reactive groups, contains at least one radical-curable group and has a molar mass of at least 400 g / mol.

[0069] Preferably, the liquid hybrid compound (B1) has a molar mass of at least 600 g / mol.

[0070] The structure of the radical-curable radical group is not further restricted, as long as it has an olefinic unsaturated double bond.

[0071] Suitable free radical-curable groups include, for example, (meth)acrylates, allyl ethers, vinyl ethers, isoprene, and butadiene.

[0072] Preferably, the hybrid compound (B1) contains at least one methacrylate group.

[0073] Furthermore, the hybrid compound (B1) preferably contains at least one isocyanate reactive group selected from the group consisting of amino groups and hydroxyl groups and combinations thereof.

[0074] In addition to the number of organic residues, the configuration of residues bonded to isocyanate reactive groups also affects the properties of the hybrid compound (B1).

[0075] Preferably, the hybrid compound (B1) contains a primary amino group, a primary hydroxyl group and / or a secondary hydroxyl group as isocyanate reactive groups.

[0076] Preferably, the primary amine and / or hydroxyl groups of the hybrid compound (B1) are bonded to a primary or secondary carbon.

[0077] Particularly preferably, the hybrid compound (B1) contains at least one primary amino group as an isocyanate reactive group and at least one (meth)acrylate group, particularly a methacrylate group as a free radical curing group.

[0078] To ensure particularly good crosslinking of the free radical curing and addition crosslinking components while maintaining high strength, the hybrid compound (B1) preferably contains, in addition to the free radical curing group and the isocyanate reactive group, another of the aforementioned groups. In other words, based on the number of isocyanate reactive groups and free radical curing groups in the hybrid compound (B1), the average functionality of the hybrid compound (B1) is preferably at least three.

[0079] The hybrid compound (B1) preferably has a molecular weight of 400 g / mol to 20,000 g / mol, more preferably 500 g / mol to 19,000 g / mol, and particularly preferably 600 g / mol to 18,000 g / mol.

[0080] If a liquid hybrid compound (B1) with a low molecular weight, such as less than 400 g / mol, is used, this may cause the passivation layer of the passivated solid isocyanate (A) to dissolve. In this case, it will be impossible to formulate a curable composition with sufficient processing time.

[0081] If a liquid hybrid compound (B1) with a very high molecular weight, such as greater than 20,000 g / mol, is used, its viscosity will increase to the point that it is impossible to formulate a homogeneous composition.

[0082] The hybrid compound (B1) can be selected from the group consisting of amine-functional hybrid compounds (B1-1), hydroxyl-functional hybrid compounds (B1-2), and combinations thereof.

[0083] Amine-functional hybrid compounds (B1-1)

[0084] The amine-functional hybrid compound (B1-1) can be obtained by a partial reaction based on the polyamine (b1-1-1) and the isocyanate-functional (meth)acrylate (b1-1-2).

[0085] The reaction of polyamine (b1-1-1) with isocyanate-functionalized (meth)acrylate (b1-1-2) can optionally be carried out with the addition of a catalyst. Suitable catalysts include tertiary amine compounds, such as triethylamine.

[0086] The structure of the polyamine (b1-1-1) is not further restricted. Polyoxyenamine (based on polyether), polyethyleneimine (polyaziridinium), polyamide amine, or phenolic amine can be used.

[0087] Preferably, a polyamine based on polyoxyenamine (b1-1-1) is used, wherein the polyoxyenamine has ethylene units, propylene (1,2-propylene and 1,3-propylene) units, tetramethylene units, tetrahydropyran units or mixtures thereof.

[0088] For example, commercially available polyoxyethylene amines can be obtained from Huntsman Corporation under the trade names Jeffamine® THF-100, Jeffamine® THF-170, Jeffamine® D-205, Jeffamine® D-230, Jeffamine® D-400, Jeffamine® D-2000, Jeffamine® D-2010, Jeffamine® D-4000, Jeffamine® T-403, Jeffamine® T-3000, Jeffamine® T-5000, Jeffamine® EDR-148, Jeffamine® EDR-176, Jeffamine® ED-600, Jeffamine® ED-900, or Jeffamine® ED-2003, or from BASF SE under the types Baxxodur® EC 130, Baxxodur® EC 280, Baxxodur® EC 301, and Baxxodur® EC 302, Baxxodur® EC 303, Baxxodur® EC 310 or Baxxodur® EC 311.

[0089] Chain extension of polyamines (b1-1-1) to form higher molecular weight polyoxyethyleneamines via pre-reaction with bismaleimide, bifunctional acrylate or higher functional acrylate, or aliphatic and / or aromatic bifunctional glycidyl ether or higher functional glycidyl ether is also within the scope of this invention.

[0090] Isocyanate-functional (meth)acrylates (b1-1-2)

[0091] Suitable isocyanate-functional (meth)acrylates (b1-1-2) are, for example, reaction products obtained by reacting an aliphatic, alicyclic, and / or aromatic at least bifunctional isocyanate (b1-1-3) with a hydroxyl-functional (meth)acrylate (b1-1-4) according to the method described in DE3 025 227 A1.

[0092] Preferably, the hydroxyl-functional (meth)acrylate (b1-1-4) and at least the difunctional isocyanate (b1-1-3) are used in excess of 20 wt% or more. The excess unreacted monomeric at least difunctional isocyanate (b1-1-3) can be separated from the reaction mixture by distillation, for example, vacuum distillation using a thin-layer, membrane, or short-path evaporator. Such distillation methods are described in Kunststoff Handbuch, Vol. 7, “Polyurethane” (GW Becker (ed.), Hanser-Verlag, Munich, 3rd ed., 1993, p. 425).

[0093] Further commercially available examples of isocyanate-functionalized (meth)acrylates (b1-1-2) include ethyl 2-isocyanate methacrylate (Karenz MOI), ethyl 2-isocyanate acrylate (Karenz AOI), 1,1-bis(acryloyloxymethyl)ethyl isocyanate (Karenz BEI), ethyl 2-(2-isocyanate ethoxy) methacrylate (Karenz MOI-EG) (available from Resonac Corporation), and an adduct of 2-hydroxyethyl acrylate with 5-isocyano-1-(isocyanomethyl)-1,3,3-trimethylcyclohexane (VESTANAT EP-DC 1241) (available from Evonik).

[0094] Examples of at least bifunctional isocyanates (b1-1-3) used for the preparation of isocyanate-functional (meth)acrylates (b1-1-2) include hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-diisocyanate dicyclohexylmethane, methylene diphenyl isocyanate, 2,4,4-trimethylhexane-1,6-diisocyanate, 2,2,4-trimethylhexane-1,6-diisocyanate, toluene-2,4-diisocyanate, and toluene-2,6-diisocyanate, which are available under the trade name Desmodur from Covestro AG or under the trade name Vestanet from Evonik Operations GmbH. Other suitable at least bifunctional isocyanates (b1-1-3) include m-tetramethylphenyldimethyl diisocyanate from Allnex Germany GmbH, as well as m-phenyldimethyl diisocyanate and 1,3-bis(isocyanatomethyl)cyclohexane, which are commercially available under the trade name Takenate from Mitsui Chemicals Inc. Other suitable at least bifunctional isocyanates (b1-1-3) include 4,4'-diisocyano-3,3'-dimethylbiphenyl (available from Nisso ChemicalEurope GmbH), and 1,5-naphthalene diisocyanate, 1,3-phenyl diisocyanate and 1,4-phenyl diisocyanate (available from TCI Chemicals). Mixtures of the aforementioned at least bifunctional diisocyanates (b1-1-3) are also included.

[0095] Examples of hydroxyl-functionalized (meth)acrylates (b1-1-4) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, di(meth)acrylate, mono(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyalkylene glycol mono(meth)acrylate, polycaprolactone (meth)acrylate, and dipentaerythritol penta(meth)acrylate. Mixtures of the above-mentioned raw materials are also included. These raw materials are commercially available from Evonik Operations GmbH, Arkema Sartomer, and GEOSpeciality Chemicals.

[0096] Optionally, one or more catalysts (b1-1-5) can be used to accelerate the reaction of at least bifunctional isocyanates (b1-1-3) with hydroxyl-functional (meth)acrylates (b1-1-4). Suitable catalysts (b1-1-5) include organometallic compounds of tin, zinc, iron, titanium, or bismuth, such as dibutyltin diacetate or dioctyltin diacetate, dibutyltin dilaurate or dioctyltin dilaurate, and tributyltin acetate. Further suitable catalysts (b1-1-5) include carboxylates of the elements mentioned above, such as tin acetate (II), tin 2-ethylhexanoate (II), zinc 2-ethylhexanoate (II), and bismuth neodecanoate (III). Suitable catalysts also include amine compounds, such as DABCO, DBU, triethylamine, and other tertiary amines.

[0097] In the synthesis of isocyanate-functional (meth)acrylates (B1-1-2), amine-functional hybrid compounds (B1-1), and hydroxyl-functional hybrid compounds (B1-2), suitable stabilizers, such as phenolic antioxidants or other free radical scavengers and / or stabilizers known to those skilled in the art, may optionally be added.

[0098] A further method for preparing the amine-functionalized hybrid compound (B1-1) involves a partial reaction of the polyamine (b1-1-1) with (meth)acrylic anhydride. (Meth)acrylic acid, present as a byproduct, may optionally be retained in the system or removed. This can be achieved, for example, by vacuum distillation using a thin-layer, membrane, or short-path evaporator. The byproduct can also be removed by washing.

[0099] Hydroxyl-functionalized hybrid compounds (B1-2)

[0100] For example, compounds based on polyethers, polyesters, polycarbonates, unhydrogenated or partially to fully hydrogenated polybutadiene, and unhydrogenated or partially to fully hydrogenated polyisoprene can be used as hybrid compounds with higher molecular weight hydroxyl functionality (B1-2).

[0101] The hydroxyl-functional hybrid compound (B1-2) can also be obtained by partial reaction of a hydroxyl-functional polyol (b1-2-1) with an isocyanate-functional (meth)acrylate (b1-1-2), as previously described for the amine-functional hybrid compound (B1-1).

[0102] Hydroxyl-functionalized polyols (b1-2-1)

[0103] The structure of the possible hydroxyl-functionalized polyols (b1-2-1) is not further limited. For example, polyether polyols or polyalkylene glycols containing ethylene units, propylene (1,2-propylene and 1,3-propylene) units, tetramethylene units, tetrahydropyran units, or mixtures thereof can be used. These are commercially available, for example, as Acclaim, Desmophen, Baycoll, Caradol, Lupronol, Voranol, Rokopol, Velvetol, Ecotrion, PolyTHF, PTG, PTMG, or PTMEG types.

[0104] In addition, polyols (b1-2-1) include polyester polyols having aliphatic and / or aromatic units, which are commercially available, for example under names such as Kuraray, CAPA, Desmophen, Baycoll, Priplast, or Placcel.

[0105] It also includes polycarbonate-based polyols (b1-2-1), which are available as Kuraray, Eternacoll or Placcel types.

[0106] Further suitable polyols (b1-2-1) are based on polybutadiene and hydrogenated polybutadiene (available as Krasol®, Polyvest®, Nisso-PB®, Poly bd or EPOL type), and polyisoprene (as poly ip type).

[0107] The types of polyols mentioned can be obtained from companies such as Evonik Operations GmbH, Covestro AG, Shell Chemicals, BASF SE, DOW, PCC Rokita SA, Mitsubishi Chemical Group, Hodogaya Chemical, Kuraray Europe GmbH, Perstorp Holding, Ingevity, Cargill, DaicelChemTech Inc., UBE Corporation, WeylChem International GmbH, Gantrade Corporation, Dairen Chemical Corporation (DCC), Cray Valley, Idemitsu Kosan Co., Ltd., and Nippon Soda Co., Ltd.

[0108] The reaction of a hydroxyl-functionalized polyol (b1-2-1) with an isocyanate-functionalized (meth)acrylate (b1-1-2) to form a hydroxyl-functionalized hybrid compound (B1-2) can be carried out in a manner similar to the reaction of the hydroxyl functional group with the isocyanate functional group described above, with the optional addition of a catalyst (b1-1-5).

[0109] A further method for preparing component (B1-2) involves a partial reaction of a hydroxyl-functionalized polyol (b1-2-1) with (meth)acrylic anhydride. (Meth)acrylic acid, as a byproduct, may optionally be retained in the system or removed. This can be achieved, for example, by vacuum distillation using a thin-layer, membrane, or short-path evaporator. The byproduct can also be removed by washing.

[0110] To accelerate the reaction of hydroxyl-functionalized polyols (b1-2-1) with (meth)acrylic anhydride, one or more catalysts (b1-2-2) can be used, such as pyridine, triethylamine, 4-(dimethylamino)pyridine, sulfuric acid, p-toluenesulfonic acid, or alkali metal hydroxides.

[0111] In the composition according to the invention, the hybrid compound (B1) is preferably present in an amount of 20 wt.% to 100 wt.% based on the total weight of component (B), more preferably in an amount of 30 wt.% to 80 wt.%.

[0112] Second liquid isocyanate reactive component (B2)

[0113] Optionally, the isocyanate reactive component (B) contains, in addition to the hybrid compound (B1), a second liquid isocyanate reactive component (B2). It contains no other radical-curable groups other than one or more isocyanate reactive groups.

[0114] In principle, the choice of component (B2) in the group consisting of alcohols, amines and thiols and mixtures thereof is unrestricted, provided that it is a liquid at room temperature.

[0115] Component (B2) is not further limited in its chemical composition. Preferably, based on the isocyanate reactive groups of component (B2), the average functionality of the second isocyanate reactive component (B2) is at least two.

[0116] The cured composition can specifically be formed from hard segments and soft segments. To form hard segments, a liquid isocyanate reactive component (B2) with a molecular weight of up to about 400 g / mol is preferably used as a so-called chain extender, which forms a high density of linking groups, such as (thio)carbamate or urea groups, together with at least a bifunctional, passivated solid isocyanate (A1) during the thermosetting step, and is then linked together by a dense network of hydrogen bonds.

[0117] To form soft segments, component (B2) preferably contains a long-chain isocyanate reactive compound with a molecular weight of 400 g / mol to 20,000 g / mol.

[0118] Isocyanate reactive compounds can also be pre-chain extended with liquid non-passivated isocyanates to form prepolymers.

[0119] Preferably, component (B2) comprises an amine. Polyether amines with a molecular weight of 600 g / mol or higher (e.g., those available as Jeffamine® D-2000 or Jeffamine® T-5000) may be used as the amine in component (B2). Also preferred are aromatic amines with a higher molecular weight, ranging from 400 g / mol to 12,000 g / mol, which, according to EP 0 071834 A1, can be obtained by alkaline hydrolysis of compounds having terminal isocyanate groups, particularly from isocyanate prepolymers. Suitable aromatic diamines are commercially available under the names Versalink® P-650 and Versalink® P-1000. Aromatic diamines (e.g., diethyltoluene diamine, available as Ethacure 100) may also be used as chain extenders.

[0120] In addition, polyols can be used as component (B2), with an average molecular weight M being particularly preferred. n Long-chain polyols ranging from 400 g / mol to 20,000 g / mol. Examples of suitable long-chain polyols include polyether-based polyols (commercially available as Acclaim® type), polyesters, and polycarbonates (available as Kuraray® or Priplast). TM (obtained as type), and polyols based on polybutadiene and hydrogenated polybutadiene (obtainable as Krasol®, Polyvest® or Nisso-PB® type).

[0121] Long-chain polyols with an average molecular weight of 2,000 g / mol to 20,000 g / mol are particularly suitable for producing curable compositions that exhibit high flexibility and low glass transition temperature at low temperatures after curing.

[0122] As a chain extender, component (B2) may contain at least one low molecular weight polyol with a molecular weight of up to 400 g / mol, such as ethylene glycol, glycerol, 1,4-butanediol or 2-ethyl-1,3-hexanediol.

[0123] Ester-based thiols (e.g., trimethylolpropane-tri-(3-mercaptopropionate) or pentaerythritol-tetra-(3-mercaptobutyrate)) are suitable for use as thiols in component (B2). Furthermore, thiol-terminated polyethers can be used as isocyanate reactive components, as can polysulfides with thiol groups or tris(3-mercaptopropyl)isocyanurate.

[0124] In the composition according to the invention, the second liquid isocyanate reactive component (B2) is preferably present in a proportion of 0 wt.% to 50 wt.% based on the total weight of component (B), more preferably in a proportion of 0 wt.% to 30 wt.%.

[0125] Solid isocyanate reactive component (B3)

[0126] In addition to the liquid hybrid compound (B1) and optionally (B2), the composition optionally contains a solid isocyanate reactive component (B3) with a melting point of at least 50°C.

[0127] The solid isocyanate reactive component (B3) may be selected from the group consisting of alcohols, amines, and thiols, and mixtures thereof. Preferably, component (B3) is selected from the group consisting of alcohols and amines.

[0128] In principle, any solid isocyanate reactive compound with a melting point of 50°C or higher, preferably 60°C or higher, especially 65°C or higher, and more preferably not higher than 200°C can be used as component (B3).

[0129] The solid isocyanate reactive component (B3) is present in the curable composition, particularly in a dispersed form, and is insoluble in the other components of component (B).

[0130] The amine of the solid isocyanate reactive component (B3) can exist in a bifunctional or higher functional form and may contain any number of additional isocyanate reactive groups. In the case of mixed functionalized amines, thiols or hydroxyl functional groups are preferably present in addition to the amine functional group. Particularly preferred is the presence of a combination of amine and hydroxyl functional groups. Examples include epoxy-amine adducts that have at least one additional hydroxyl group in addition to the amine functional group.

[0131] Compounds with a molecular weight of less than 5,000 g / mol, more preferably less than 2,000 g / mol, and particularly preferably less than 1,000 g / mol are preferred as the reactive component of the solid second isocyanate (B3).

[0132] Examples of solid isocyanate reactive components (B3) include 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dichlorodiphenylmethane, 4,4'-diaminodiphenyl ether, bis(4-amino-3,5-diethylphenyl)methane, pentaerythritol, trimethylolpropane, or trimethylolethane.

[0133] Suitable commercially available products include, for example, Aradur 9664-1 and Aradur 9719-1 from Huntsman and Charmor PM15 from Perstorp.

[0134] For example, commercially available epoxy-amine adducts are available from ADEKA under the names EH-5011S, EH-5046S, EH-5015SS and EH-5057P, from Evonik under the names Ancamine 2014FG or Ancamine 2442, or from Sanho Chemical under the names Fujicure FXR-1020, Fujicure FXR-1030, Fujicure FXR-1081 or Fujicure FXR-1121.

[0135] Based on the weight of component (B), the proportion of the solid isocyanate reactive component (B3) is preferably in the range of 0 wt.% to 40 wt.%, more preferably 1 wt.% to 25 wt.%.

[0136] In the compositions according to the invention, the isocyanate reactive component (B) is preferably present in a proportion of 5 wt.% to 90 wt.% based on the total weight of the composition, more preferably in a proportion of 10 wt.% to 70 wt.%.

[0137] Component (C): Initiator system for free radical polymerization

[0138] In addition to at least a bifunctional solid passivated isocyanate (A) and an isocyanate reactive component (B) (containing at least a hybrid compound (B1)), the curable composition according to the invention further comprises an initiator system (C) for free radical polymerization, which comprises a first initiator (C1) and a second initiator (C2), wherein the first initiator (C1) is a free radical photoinitiator (C1) and the second initiator (C2) is a free radical initiator for thermosetting.

[0139] Preferably, the initiator system (C) consists of a first initiator (C1) and a second initiator (C2).

[0140] First initiator (C1)

[0141] As a free radical photoinitiator, the first initiator (C1) enables the curable composition to be photofixed, thereby achieving crosslinking of the free radical curable groups of the hybrid compound (B1) and other optional added free radical curable formulation components.

[0142] All standard commercially available compounds can be used as free radical photoinitiators (C1), such as α-hydroxy ketones, benzophenone, α,α'-diethoxyacetophenone, 4,4-diethylaminobenzophenone, 2,2-dimethoxy-2-phenylacetophenone, 4-isopropylphenyl-2-hydroxy-2-propyl ketone, 1-hydroxycyclohexylphenyl ketone, isoamyl p-dimethylaminobenzoate, methyl 4-dimethylaminobenzoate, methyl o-benzoylbenzoate, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, 2-isopropylthioxanthone, dibenzocycloheptenone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and diacylphosphine oxide, wherein the compounds mentioned above can be used alone or in combination of two or more of the compounds mentioned as free radical photoinitiators (C1).

[0143] IRGACURE from BASF SE TM Types can be used as free radical photoinitiators (C1) that can be activated by UV radiation, such as 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, and IRGACURE TPO-L. Additionally, DAROCUR from BASF SE can be used. TM Types such as DAROCUR MBF, DAROCUR 1173, DAROCUR TPO and DAROCUR 4265.

[0144] The above list is intended as examples of free radical photoinitiators (C1) and should in no way be construed as limiting.

[0145] The free radical photoinitiator used as component (C1) in the composition according to the invention is preferably activated by photochemical radiation with a wavelength of 200 nm to 400 nm, more preferably 250 nm to 365 nm.

[0146] If necessary, the free radical photoinitiator (C1) can be combined with a suitable sensitizer.

[0147] Each free radical photoinitiator (C1) is present in the composition, particularly in a proportion of 0.01 wt.% to 5 wt.%, preferably 0.5 wt.% to 3 wt.%, based on the total weight of the composition.

[0148] Second initiator (C2)

[0149] The second initiator (C2) (i.e., the free radical initiator for thermosetting) can be selected from, for example, peroxides and / or benzylpinacol.

[0150] Suitable peroxide compounds include, for example, peroxy(di)esters, hydroperoxides, (di)alkyl peroxides, ketone peroxides, perketals, peracids, and peroxymonocarbonates. Furthermore, peroxydicarbonates (e.g., those described in WO 2023 030 763 A1) may be advantageously used in the compositions according to the invention.

[0151] Examples of suitable peroxide esters include cumene peroxyneodecanate, 1,1,3,3-tetramethylbutyl peroxyneodecanate, tert-amyl peroxyneodecanate, tert-butyl peroxyneodecanate, 1,1,3,3-tetramethylbutyl peroxyneopentate, tert-amyl peroxyneopentate, tert-butyl peroxyneopentate, didecanoyl peroxide, dilauroyl peroxide, 2,5-dimethyl-2,5-di-(2-ethylhexanoylperoxy)hexane, 1,1,3,3-tetramethylbutyl-peroxy-2-ethylhexanoate, tert-amyl peroxy-2-ethylhexanoate, benzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxyacetate, and tert-butyl peroxybenzoate.

[0152] Examples of suitable hydroperoxides include dicumylbenzene monohydroperoxide, p-menthane hydroperoxide, cumylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, tert-butyl hydroperoxide, and tert-amyl hydroperoxide.

[0153] Examples of suitable peroxy monocarbonates include tert-amyl-peroxy-2-ethylhexyl carbonate, tert-butyl-peroxyisopropyl carbonate, and tert-butyl-peroxy-2-ethylhexyl carbonate.

[0154] Examples of suitable peroxydicarbonates include di-(4-tert-butyl-cyclohexyl)peroxydicarbonate, di-(2-ethylhexyl)peroxydicarbonate, di-n-butylperoxydicarbonate, dicerylperoxydicarbonate and dimyristylperoxydicarbonate.

[0155] Benpinacol and its derivatives (such as those described in US 4,288,527 A) can also be used as free radical initiators (C2) for thermosetting. These include, in particular, halogenated, alkylated, and methoxy-substituted benpinacols.

[0156] In addition, protected benzipineols can be used as components (C2). These can be mono- or doubly protected, and include silyl-protected, particularly mono- and bis-trialkylsilyl-protected benzipineols.

[0157] Examples of benzinolates that can be used in the curable compositions according to the present invention include 1,1,2,2-tetraphenyl-1,2-ethylene glycol, 1,1,2,2-tetra(4-methylphenyl)-1,2-ethylene glycol, 1,1,2,2-tetra(4-methoxyphenyl)-1,2-ethylene glycol, 1,1,2,2-tetra(4-chlorophenyl)-1,2-ethylene glycol, 1-hydroxy-2-trimethylsiloxy-1,1,2,2-tetraphenylethane, 1,1,2,2-tetraphenyl-1,2-bis-(trimethylsiloxy)-ethane, and 1,1,2,2-tetra(4-methylphenyl)-1,2-bis-(trimethylsiloxy)-ethane.

[0158] In the composition according to the invention, the free radical initiator (C2) for thermosetting is present in a proportion of 0.01 wt.% to 10 wt.%, preferably 0.1 wt.% to 5 wt.%, based on the total weight of the composition.

[0159] Component (D): Additional free radical curable component

[0160] The curable composition according to the invention optionally includes an additional radical-curable component (D), which contains at least one radical-radiation-curable compound.

[0161] Additional free radical radiation-curing component (D) is specifically designed to ensure high gloss fixation strength.

[0162] Additional free radical curable component (D) can be reacted with both a free radical photoinitiator (C1) and a free radical initiator (C2) for thermosetting and incorporated into the polymer network.

[0163] Additional free radical-curable compounds (D) are not subject to any further structural restrictions, as long as they contain olefinic unsaturated double bonds.

[0164] Suitable examples include (meth)acrylates, allyl ethers, vinyl ethers, isoprene, and butadiene.

[0165] Preferably, the additional radical-curable compound (D) is at least bifunctional with respect to the olefinic unsaturated double bond.

[0166] Radical-curable compounds based on (meth)acrylates are preferably used as component (D). For example, both aliphatic and aromatic (meth)acrylates can be used.

[0167] Herein and below, derivatives of both acrylic acid and methacrylic acid, as well as combinations and mixtures thereof, are referred to as (meth)acrylates.

[0168] For example, the following radiation-curable compounds are suitable: isoborneol 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-dimethylpropyl acrylate. Acrylates, 4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,10-decanediol diacrylate, tricyclodecanediethanol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polybutadiene diacrylate, cyclohexanediethanol diacrylate, diurethane acrylates of monomers, oligomers or polymers of diols and polyols, trimethylolpropane triacrylate (TMPTA) and dipentaerythritol hexaacrylate (DPHA), and combinations thereof. Advantageously, higher functional acrylates derived from branched or dendritic alcohols may also be used.

[0169] Similar methacrylates are also within the scope of this invention.

[0170] In addition, 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®. Compounds containing allyl groups induce a rapid curing process, especially in the presence of thiols. Unhydrogenated polybutadiene with free double bonds (e.g., Poly BD® type) can also be used as radiation-curable compounds.

[0171] Uracarbamate acrylates based on polyester, polyether, polycarbonate diol and / or (hydrogenated) polybutadiene diol can be used as higher molecular weight radiation-curable compounds in the second curable component (B).

[0172] Combinations of various radiation-curable compounds are also within the scope of this invention.

[0173] In the compositions according to the invention, each free radical curable component (D) is present, in particular, in a proportion of 0 wt.% to 50 wt.%, preferably in a proportion of 5 wt.% to 30 wt.%, based on the total weight of the curable composition.

[0174] Component (E): Additives

[0175] In addition to components (A) through (D), the curable compositions according to the invention may further contain other additives (E). Non-exhaustive examples include catalysts, toughening modifiers (such as core-shell particles or block copolymers), anti-aging agents, dyes, fluorescent agents, pigments, thixotropic agents, thickeners, heat stabilizers, stabilizers, antioxidants, plasticizers, fillers, flame retardants, thermally and / or electrically conductive particles, corrosion inhibitors, water absorbents, diluents, flow and wetting additives, tackifiers, and combinations thereof, which may be used as additives (E).

[0176] In principle, inert organic solvents can also be used as diluents, as long as they do not dissolve the passivated solid polyisocyanate (A). However, it is preferable that the curable composition does not contain inert organic solvents, as the use of such solvents is environmentally disadvantageous and therefore not preferred. In principle, water can also be used as a dispersion medium. However, this necessitates a complex drying step in the processing of the curable composition, therefore the use of aqueous dispersions is also not preferred.

[0177] Optionally, surface-modified fumed silica is preferred as a thixotropic agent.

[0178] Based on the total weight of the composition, the additive (E) is preferably present in the curable composition in a proportion of 0 wt.% to 80 wt.%, particularly preferably in a proportion of 0 wt.% to 50 wt.%.

[0179] Formulation of the curable composition according to the present invention

[0180] The curable composition according to the invention preferably comprises or consists of the components (A) to (E) mentioned above. Advantageously, the curable composition contains at least one additive (E).

[0181] According to a first preferred embodiment, the curable composition according to the present invention comprises the following components:

[0182] (A) At least a bifunctional, passivated solid isocyanate;

[0183] (B) An isocyanate reactive component comprising at least one hybrid compound (B1), wherein the hybrid compound (B1) contains, in addition to at least one isocyanate reactive group, at least one radical-curable group, wherein the molar mass of the hybrid compound (B1) is at least 400 g / mol; and

[0184] (C) An initiator system (C) for free radical polymerization, comprising a first initiator (C1) and a second initiator (C2), wherein the first initiator (C1) is a free radical photoinitiator (C1), and the second initiator (C2) is a free radical initiator (C2) for thermosetting.

[0185] In a second preferred embodiment, the composition according to the invention comprises the following components:

[0186] (A) At least a bifunctional, passivated solid isocyanate;

[0187] (B) An isocyanate reactive component comprising at least one hybrid compound (B1), wherein the hybrid compound (B1) contains at least one isocyanate reactive group and at least one radical-curable group, wherein the molar mass of the hybrid compound (B1) is at least 400 g / mol;

[0188] (C) An initiator system (C) for free radical polymerization, comprising a first initiator (C1) and a second initiator (C2), wherein the first initiator (C1) is a free radical photoinitiator (C1), and the second initiator (C2) is a free radical initiator (C2) for thermosetting; and

[0189] (D) At least one additional radical-curable component (D).

[0190] By adding an additional radical-curable component (D), the light-fixing strength of the composition can be adjusted and advantageously improved. As a radical initiator for thermosetting, the second initiator (C2) ensures that the additional radical-curable component (D) is fully cured in the shaded area during the final thermosetting step.

[0191] In a third preferred embodiment, the curable composition according to the invention comprises the following components:

[0192] (A) At least a bifunctional, passivated solid isocyanate;

[0193] (B) An isocyanate reactive component comprising at least one hybrid compound (B1) and at least one second liquid isocyanate reactive component (B2), wherein the hybrid compound (B1) contains at least one isocyanate reactive group and at least one radical-curable group, wherein the molar mass of the hybrid compound (B1) is at least 400 g / mol; and

[0194] (C) An initiator system (C) for free radical polymerization, comprising a first initiator (C1) and a second initiator (C2), wherein the first initiator (C1) is a free radical photoinitiator (C1), and the second photoinitiator (C2) is a free radical initiator for thermosetting.

[0195] By adding a second liquid isocyanate reactive component (B2) and optionally one or more chain extenders, the mechanical properties (e.g., elastic modulus and glass transition temperature) of the curable composition can be tuned over a wide range. Furthermore, by combining a bifunctional isocyanate reactive compound and a higher-functionality isocyanate reactive compound (B2), the crosslinking density can be adjusted almost arbitrarily, provided that a polymer network is formed on at least a bifunctional isocyanate (A) via an addition reaction upon heating.

[0196] In a fourth preferred embodiment, the composition according to the invention comprises the following components:

[0197] (A) At least a bifunctional, passivated solid isocyanate;

[0198] (B) An isocyanate reactive component comprising at least one hybrid compound (B1) and at least one solid isocyanate reactive component (B3), wherein the hybrid compound (B1) contains at least one isocyanate reactive group and at least one radical-curable group, wherein the molar mass of the hybrid compound (B1) is at least 400 g / mol; and

[0199] (C) An initiator system (C) for free radical polymerization, comprising a first initiator (C1) and a second initiator (C2), wherein the first initiator (C1) is a free radical photoinitiator (C1), and the second photoinitiator (C2) is a free radical initiator for thermosetting.

[0200] By adding a solid isocyanate reactive component (B3) with a melting point of 50°C or higher, a cured composition with particularly good temperature resistance can be obtained. Furthermore, adhesion, especially to metal surfaces, can be improved.

[0201] Performance of the composition according to the present invention

[0202] The compositions according to the invention are liquid at room temperature and can be formulated into one-component compositions. Preferably, the curable compositions are one-component compositions.

[0203] Due to the passivation of at least a bifunctional solid isocyanate (A1), the composition remains processable at room temperature for at least a certain period of time. The composition is fully processable if the viscosity increases by less than 25% after storage relative to the viscosity at the start of storage. The curable composition according to the invention meets this criterion even after being stored at room temperature for 72 hours.

[0204] The composition according to the invention can also be fixed within seconds by photochemical radiation, thereby allowing precise adjustment of the shape and position of the mating parts and the adhesive (i.e., the fixed composition) during the bonding process. A light-fixing strength of preferably at least 0.3 MPa (glass / aluminum) is achieved.

[0205] By appropriately selecting the hybrid component (B1) and optionally an additional free radical curable component (D), the photocuring rate and the resulting photocuring intensity can be advantageously influenced. Therefore, the curable composition according to the invention allows the oven process for thermocuring to be separated from further manufacturing steps in both time and space. This enables higher production volumes in industrial manufacturing processes.

[0206] Using a free radical initiator for thermosetting as a second initiator (C2) ensures complete crosslinking of free radical curable groups and components, especially in shaded areas, thereby achieving uniform properties of the cured composition throughout its entire volume.

[0207] The hybrid compound (B1) also enables reliable connectivity of networks from both light and shadow regions, resulting in high final strength. Preferably, the cured composition has a compressive shear strength (Al / Al) of at least 1 MPa, more preferably at least 2.5 MPa.

[0208] The cured composition also exhibits a consistently low modulus of elasticity over a wide temperature range and provides high heat resistance and resistance to media. Specifically, the cured composition has an modulus of elasticity ranging from 5 MPa to 500 MPa, which remains substantially constant over a temperature range of -35°C to 100°C. This is also attributed to the fact that the glass transition temperature of the cured composition is typically -40°C or lower.

[0209] Furthermore, the potential volume reduction (shrinkage) of the optical network helps to offset the volume expansion during isocyanate curing, making the curable composition suitable for bonding optical modules, particularly in the camera field. Based on the initial volume of the composition after addition, the volume change of the composition during setting and curing can range, for example, from -10% to +20%.

[0210] Curable compositions that undergo volume reduction during the curing process are also suitable for formulating thermally and / or electrically conductive systems.

[0211] Processing method using the composition according to the invention

[0212] The curable compositions according to the invention are characterized in that they can be fixed by light and subsequently cured at low temperatures. The thermosetting step can be performed independently in time and space.

[0213] The corresponding methods for bonding, casting, or coating a substrate using the curable composition according to the invention include the following steps:

[0214] (a) Applying the curable composition to a first substrate;

[0215] (b) Optionally, a second substrate is provided, thereby forming a substrate composite;

[0216] (c) Fixing the curable composition with photochemical radiation; and

[0217] (d) The fixed composition on the substrate and / or in the substrate composite is thermocured by heating to a temperature of at least 60°C.

[0218] In particular, curable compositions are suitable for applications where the development of strength needs to be purposefully controlled by light fixation, while ensuring reliable curing in shaded areas, especially in the case of substrates that cannot be penetrated by light. This performance characteristic is particularly needed in the manufacture of electro-optical elements (e.g., camera modules), the bonding of displays, or casting compounds with complex geometries (e.g., sensor casting compounds).

[0219] Alignment of components (e.g., during active alignment) can lead to uneven adhesive thickness between mating parts. Consequently, shrinkage or volume expansion during curing has varying effects, resulting in localized stress introduction within the components. Adhesives with low or preferably zero shrinkage (i.e., substantially constant volume during bonding) mitigate this problem.

[0220] Thermosetting is preferably carried out at a temperature at which at least a bifunctional, passivated solid isocyanate (A) dissolves or melts, thereby decomposing the passivated shell, particularly the polyurea shell. Thermosetting is preferably carried out at a temperature of at least 50°C, preferably at least 60°C, but not higher than 200°C, and more preferably not higher than 180°C.

[0221] The composition for curing can be heated, for example, in a convection oven using thermoelectric electrodes, IR emitters, lasers, microwaves, or induction. Depending on the heat source and temperature, curing can occur from seconds to a maximum of two hours.

[0222] By using the curable composition according to the invention, high positional accuracy of the joined elements can be achieved prior to final curing. Therefore, conventional fixing aids, which are practically unsuitable for miniaturized elements or involve unreasonable additional work, can be eliminated.

[0223] Measurement methods and definitions used

[0224] room temperature

[0225] Room temperature is defined as 23℃±2℃.

[0226] Particle size distribution

[0227] According to ISO 13320, particle size distribution is determined by laser scattering using a Microtrac S3500 particle size analyzer. The d95 value represents the distribution based on the volumetric particle diameter.

[0228] Optical fixation stability

[0229] The light-fixed intensity was determined using a "Die Shear" tester (model DAGE BTSERIES4000PX) from Dage Semiconductor GmbH. The test instructions were based on MIL-STD-883, Method 2019.5. A single glass cube (4 mm in size) was used. 4 mm 4 mm) were respectively bonded to a second sample (20 mm in size) made of clad aluminum. 20 mm (5 mm). To do this, a drop of curable composition is applied to an aluminum sample and bonded to a glass cube. The adhesive layer thickness and overlap are adjusted to 0.1 mm using spacers and an adhesive device. A DELOLUX 20 / 400 LED light at 200 mW / cm² is used. 2 The intensity was used to irradiate the bonded sample at a wavelength of 400 nm for 10 s.

[0230] Compressive shear strength

[0231] Using their respective compositions, two specimens (20 mm in size) were prepared from free-clad aluminum. 20 mm Adhesive beads (5 mm) were bonded with a 5 mm overlap. For this purpose, beads of the composition were applied to the first specimen. The second specimen was then bonded. The adhesive layer thickness and overlap were adjusted to 0.1 mm using spacers and an adhesive device. The specimens were then heat-cured for 60 min in a preheated convection oven at 120°C. Prior to testing, the specimens were conditioned at room temperature for 24 hours.

[0232] Glass transition temperature and storage modulus

[0233] The dynamic mechanical properties of the cured composition were determined by dynamic thermal mechanical analysis (DMTA) according to ISO 6721. The measurement was performed at 15... 5 0.5 mm 3 The specimens were cured in a suitable plastic mold at 120 °C for 60 min. The glass transition temperature was defined as the value at which the absolute value of the first derivative of the storage modulus (E') becomes minimum (inflection point, see ISO 6721-11:2012, section 3.1). The storage modulus was determined at various temperatures according to ISO 6721-4:2008. Measurements were taken over a temperature range of 0 °C to 300 °C at a heating rate of 3 K / min, a frequency of 1 Hz, and an amplitude of 30 µm. A Netzsch DMA 242E was used as the measuring instrument.

[0234] GPC Measurement

[0235] The average molar mass M was measured using a Viscotek TDA 302 (refractive index and viscosity detector) available from Malvern Panalytical GmbH. n The measurements were performed. The GPC columns used were Viscotek LT4000L (mixed bed) and Viscotek T1000 (single-well) types, and M... n Calibration was performed using polystyrene calibration standards ranging from 162 Da to 51,150 Da. Tetrahydrofuran was used as the mobile phase. The flow rate was 1 mL / min at a measurement temperature of 35 °C. To improve the detectability of amines using liquid chromatography and the column combination, the amine functional groups were saturated with an excess of derivatizing reagent (e.g., hexahydro-4-methylphthalic anhydride) during sample preparation. Alternative techniques for amine derivatization are known to those skilled in the art. For sample preparation, 40 mg of sample was dissolved in 10 mL of THF, and 15 µL of derivatizing reagent was added. After a holding time of 15 min, the solution was filtered through a syringe filter (0.2 µm), and 100 µL of the solution was injected through the injection loop.

[0236] Viscosity

[0237] Viscosity was measured using a Physica MCR302 rheometer from Anton Paar, with a standardized PP20 measuring cone, at 23°C and a 200 μm gap, at a shear rate of 10 / s. To assess processability at room temperature, viscosity measurements were repeated after 72 hours. The compositions according to the invention are processable for at least 72 hours. This criterion is met if the viscosity increases by less than 25% over a 72-hour period when stored at room temperature.

[0238] Volume change / shrinkage

[0239] According to IN 66137-2 (Determination of Solid Density), the volume was measured using a PycnomaticATC helium hydrometer from Porotec Pycnomatic. Both the density of the curable composition and the density of the cured composition were determined. To measure the density of the cured adhesive, 28 cylindrical specimens (1 mm thick, 22 mm in diameter) were prepared using a suitable mold. A DELOLUX 20 / 400 LED lamp at 200 mW / cm² was then used. 2 The sample was irradiated at a wavelength of 400 nm for 60 seconds. Subsequent thermosetting was performed in a preheated convection oven at 120°C for 60 minutes. Prior to testing, the test specimens were conditioned at room temperature for 24 hours. Since no measurable mass loss occurred during curing, the volume change was calculated as follows:

[0240] S = 1 – ρL / ρS.

[0241] Volume shrinkage: S

[0242] Density of liquid adhesive: ρL

[0243] Density of the cured adhesive: ρS

[0244] Preparation Examples

[0245] To prepare the curable composition according to the invention, a hybrid compound (B1) and optionally a second liquid isocyanate reactive component (B2) are mixed with a passivating agent (A2), and micronized solid isocyanate (A1) is added. The remaining components are then added at the concentrations (by weight percentage) specified in the table and mixed together. The mixing is carried out in a Labotop (PCLaborsysteme) with sickle-shaped kneading arms. The composition is then degassed and filled into a cartridge.

[0246] Curing of the curable composition and comparative composition according to the invention begins when the passivated solid isocyanate (A) dissolves or melts at elevated temperatures and the passivation shell decomposes. Curing of the curable composition and comparative embodiment according to the invention is carried out by heating to 120°C for 60 min. Depending on the type and amount of passivating agent (A2) used to passivate the polyisocyanate (A1), the curing temperature may need to be adjusted.

[0247] Energy input for thermosetting can be provided through convection (e.g., in a convection oven), through heat conduction (e.g., using a heating plate or thermoelectrodes), or through electromagnetic radiation (e.g., using an IR radiation source, laser, microwave, or induction).

[0248] Synthesis Examples

[0249] Synthesis Example 1: Amine-functional hybrid compound (B1-1-1)

[0250] 503.30 g of polyoxyethylene amine Jeffamine T-5000 (Huntsman Corporation) (b1-1-1) was placed in a suitable reaction vessel. 0.27 g of hydroquinone monomethyl ether (Sigma Aldrich) and 0.27 g of 2,6-di-tert-butyl-4-methylphenol (Sigma Aldrich) were added and dissolved. Under continuous stirring, 27.18 g of ethyl 2-isocyanate methacrylate Karenz MOI (Resonac Corporation) (b1-1-2) was gradually added, and the temperature was then raised to 40 °C. The reaction was maintained at this temperature for another 30 minutes, and the disappearance of NCO absorption in the infrared absorption spectrum was monitored. After the reaction was complete, the reaction was stopped. The resulting product was an amine-functionalized hybrid compound (B1-1), with an average of one amino group and two methacrylate groups, and an average molar mass M. n It is 8,150 g / mol.

[0251] Synthesis Example 2: Amine-functional hybrid compound (B1-1-2)

[0252] 453.70 g of polyoxyethylene amine Jeffamine T-3000 (Huntsman Corporation) (b1-1-1) was placed in a suitable reaction vessel. 0.26 g of hydroquinone monomethyl ether (Sigma Aldrich) and 0.26 g of 2,6-di-tert-butyl-4-methylphenol (Sigma Aldrich) were added and dissolved. Under continuous stirring, 45.23 g of 2-isocyanoethyl methacrylate Karenz MOI (Resonac Corporation) (b1-1-2) was gradually added, and the temperature was then raised to 40 °C. The reaction was maintained at this temperature for another 30 minutes, and the disappearance of NCO absorption in the infrared absorption spectrum was monitored. After the reaction was complete, the reaction was stopped. The resulting product was an amine-functionalized hybrid compound (B1-1-2), with an average of one amino group and two methacrylate groups, and an average molar mass M. n It is 4,947 g / mol.

[0253] Synthesis Example 3: Amine-functional hybrid compound (B1-1-3)

[0254] 405.30 g of polyoxyethylene amine Jeffamine THF-100 (Huntsman Corporation) (b1-1-1) was placed in a suitable reaction vessel. 0.24 g of hydroquinone monomethyl ether (Sigma Aldrich) and 0.24 g of 2,6-di-tert-butyl-4-methylphenol (Sigma Aldrich) were added and dissolved. Under continuous stirring, 62.20 g of ethyl 2-isocyanate methacrylate Karenz MOI (Resonac Corporation) (b1-1-2) was gradually added, and the temperature was then raised to 40 °C. The reaction was maintained at this temperature for another 30 minutes, and the disappearance of NCO absorption in the infrared absorption spectrum was monitored. After the reaction was complete, the reaction was stopped. The resulting product was an amine-functionalized hybrid compound (B1-1-3), with an average of one amino group and one methacrylate group, and an average molar mass M. n It is 2,074 g / mol.

[0255] Synthesis Example 4: Hydroxyl-functional hybrid compound (B1-2-1)

[0256] 611.22 g of hydrogenated hydroxyl-functionalized polybutadiene Krasol HLBH-P 3000 (Cray Valley) (b1-2-1) was placed in a suitable reaction vessel. 0.25 g of hydroquinone monomethyl ether (Sigma Aldrich) and 0.25 g of 2,6-di-tert-butyl-4-methylphenol (Sigma Aldrich) were added and dissolved. Under continuous stirring, 29.04 g of ethyl 2-isocyanate methacrylate (Karenz MOI (Resonac Corporation)) (b1-1-2) was gradually added. 0.12 g of dibutyltin dilaurate (Sigma Aldrich) was added as a catalyst, and the temperature was raised to 60 °C. The reaction was maintained at this temperature for 3 hours, and the disappearance of NCO absorption in the infrared absorption spectrum was monitored. After the reaction was complete, it was stopped. The resulting product was a hydroxyl-functionalized hybrid compound (B1-2-1), with an average of one hydroxyl group and one methacrylate group, and an average molar mass M. n It is 5,489 g / mol.

[0257] Implementation Examples

[0258] The following list shows all the compounds and their abbreviations used in the preparation of curable compositions.

[0259] Component (A): At least bifunctional, passivated solid isocyanate

[0260] A1-1 - Thanecure T9 SF AD-V - Micronized TDI (TSE Industries)

[0261] A1-2 - Desmodur Z2589 - Microparticle-sized IPDI trimer (Covestro AG)

[0262] A2-1 - Jeffamine D-400 - Liquid Polyetheramine (Huntsman Corporation)

[0263] Component (B): Isocyanate reactive component

[0264] B1-1-1 - Amine-functionalized hybrid compound according to Synthesis Example 1

[0265] B1-1-2 - Amine-functionalized hybrid compounds according to Synthesis Example 2

[0266] B1-1-3 - Amine-functionalized hybrid compounds according to Synthesis Example 3

[0267] B1-2-1 - Hydroxyl-functionalized hybrid compound according to Synthesis Example 4

[0268] B1-2-2 - VISIOMER HEMA - 2-Hydroxyethyl Methacrylate (Evonik Industries)

[0269] B2-1 - Jeffamine T-5000 - Liquid Polyetheramine (Huntsman Corporation)

[0270] B2-2 - Ethacure 100 Plus - Diethyltoluenediamine (liquid) as a chain extender (Albemarle Corporation)

[0271] B2-3 - Krasol HLBH-P 3000 - Liquid Polybutadiene Polyol (Cray Valley)

[0272] B2-4 - Jeffamine T-3000 - Liquid Polyetheramine (Huntsman Corporation)

[0273] B3-1 - Ajicure PN-23J - Amine adduct (solid, Ajinomoto)

[0274] Component (C): Initiator system for free radical polymerization

[0275] C1-1 - Irgacure TPO-L - Ethyl-(2,4,6-trimethylbenzoyl)phenylphosphonite (IGMResins)

[0276] C1-2 - Irgacure TPO - Trimethylbenzoyl diphenylphosphine oxide (IGM Resins)

[0277] C2-1 - TBPND - tert-butyl peroxyneodecanate (United Initiators)

[0278] C2-2 - Peroxan APO - tert-amyl peroxy-2-ethylhexanoate (Pergan)

[0279] Component (D): Additional free radical curable component

[0280] D-1 - SR350D - Trimethylolpropane Trimethacrylate (Arkema)

[0281] D-2 - SR324 - C16-C18 methacrylate (Arkema)

[0282] D-3 - SR834 - Tricyclodecanediethanol dimethacrylate (Arkema)

[0283] D-4 - VISIOMER IBOMA - Isoborneol Methacrylate (Evonik Industries)

[0284] Component (E): Additives

[0285] E-1 - AMMO - 3-aminopropyltrimethoxysilane (adhesive) (Evonik Industries)

[0286] E-2 - HQMME - Hydroquinone Monomethyl Ether (Stabilizer) (Sigma Aldrich)

[0287] E-3 - Special Black - Dye (Palmer Holland)

[0288] E-4 - Tinuvin 292 - HALS (BASF SE)

[0289] E-5 - Triisododecyl phosphite - (Sigma Aldrich)

[0290] E-6 - Cab-O-Sil TS720 - Fumed Amorphous Silica (Cabot Corporation)

[0291] E-7 - Denka Fused Silica FB-74 - Quartz (Denka Company Ltd.)

[0292] E-8 - Bismuth neodecanoate (Sigma Aldrich)

[0293] E-9 - Aerosil R-805 - Fumed Amorphous Silica (Evonik Industries)

[0294] Curable compositions were formulated using the proportions of components (A) to (E) specified in Tables 1 to 3 below. Examples 1 to 15 according to the invention were compared with Comparative Examples 1 to 4. The proportions of the components are given in wt.% based on the total weight of the compositions.

[0295] Table 1: Examples and Comparative Examples

[0296]

[0297] 1） The value is too low to be measured.

[0298] 2） Unable to determine

[0299] Table 2: Examples and Comparative Examples

[0300]

[0301]

[0302] 1） The value is too low to be measured.

[0303] 2） The adhesive cannot be prepared; its curing...

[0304] According to a preferred embodiment, each of Examples 1 to 12 of the present invention comprises at least a bifunctional, passivated solid isocyanate (A), an isocyanate reactive component (B) (containing at least one hybrid compound (B1)), and an initiator system (C) for free radical polymerization, which consists of a free radical photoinitiator as a first photoinitiator (C1) and a free radical initiator for thermosetting as a second initiator (C2).

[0305] The compositions according to the invention can achieve an initial strength (glass / aluminum) higher than 0.3 MPa through photo-fixation. During thermosetting, a compressive shear strength (aluminum / aluminum) of at least 2.5 MPa is achieved.

[0306] In addition to the essential components, the composition according to Example 1 also contains a second liquid isocyanate reactive component (B2) as a chain extender, an additional further free radical curable component (D), and an additive (E). The measured light-fixed strength was 0.75 MPa. After final thermosetting, the cured composition achieved a compressive shear strength of 4.5 MPa.

[0307] By adding an amine (B3-1, Example 2) that is solid at room temperature, i.e., an additional solid isocyanate reactive component (B3), the compressive shear strength can be increased to 6.4 MPa while maintaining a consistently high light-fixed strength of 0.75 MPa.

[0308] The compositions of Comparative Examples 1 and 3 do not contain any hybrid compound (B1), and the light-fixed intensity after irradiation is not measurable. Thermosetting of the compositions may still be possible without restriction.

[0309] As shown in Comparative Example 2, if the second initiator (C2), i.e., the free radical initiator used for thermosetting, is omitted, sufficient adhesion cannot be achieved in the shaded area. The compressive shear strength is 0.1 MPa.

[0310] Even without the addition of additional radical-curable components (D), according to Example 3, a light-fixing intensity of 0.31 MPa was achieved by the radical-curable groups of the hybrid compound (B1).

[0311] Various mixtures of additives are shown in Examples 4 to 6 of the present invention.

[0312] In Example 7, a bifunctional hybrid compound (B1-1-3) having both amino and methacrylate groups was used. This composition meets all technical requirements.

[0313] In Example 8, the addition of stabilizer (E-2) was omitted. The composition can still be processed without restriction.

[0314] Examples 9 and 10 each comprise a hydroxyl-functionalized hybrid compound (B1-2-1). In Example 11, an alternative polyisocyanate (A1) is used.

[0315] Comparative Example 4 contains a hybrid compound (B1) (B1-2-2) having hydroxyl and methacrylate groups. The molar mass of compound B1-2-2 is less than 400 g / mol. This comparative composition was already cured during production; further processing was not possible.

[0316] Example 11 illustrates a variation involving multiple components. This composition achieves a high gloss fixation strength of 1.43 MPa.

[0317] In Example 12, a second liquid isocyanate reactive component (B2) was added. The cured composition achieved a compressive shear strength of 9.4 MPa.

[0318] Table 3: Volume changes of exemplary compositions.

[0319]

[0320] Examples 13 through 15 illustrate a series of measurements used to monitor volume changes in the curable composition during curing. By adding an increased amount of additional radical-curable component (D), the density of the radical-curable network can be increased, and the volume expansion during thermal isocyanate curing can be offset. The composition can be formulated to exhibit either volume expansion or volume reduction (shrinkage). In extreme cases, the volume shrinkage of the composition after curing can be zero.

Claims

1. A composition that can be photocured and thermocured, said composition comprising: (A) At least a bifunctional, passivated solid isocyanate, (B) An isocyanate reactive component comprising at least one liquid hybrid compound (B1), said hybrid compound (B1) containing, in addition to at least one isocyanate reactive group, at least one radical-curable group, wherein the molar mass of said hybrid compound (B1) is at least 400 g / mol, and (C) An initiator system for free radical polymerization, comprising a first initiator (C1) and a second initiator (C2), wherein the first initiator (C1) is a free radical photoinitiator and the second initiator (C2) is a free radical initiator for thermosetting.

2. The composition according to claim 1, wherein, At least one free radical-curable group of the hybrid compound (B1) is selected from the group consisting of (meth)acrylate groups, allyl ether groups, vinyl ether groups, isoprene groups and butadiene groups, and combinations thereof.

3. The composition according to claim 1 or 2, wherein, At least one isocyanate reactive group of the hybrid compound (B1) is selected from the group consisting of amino groups and hydroxyl groups, and combinations thereof.

4. The composition according to any one of the preceding claims, wherein, At least one isocyanate reactive group of the hybrid compound (B1) is bonded to a primary or secondary carbon of the hybrid compound (B1).

5. The composition according to any one of the preceding claims, wherein, The hybrid compound (B1) contains at least one primary amino group as an isocyanate reactive group, and at least one (meth)acrylate group, particularly a methacrylate group, as a free radical curing group.

6. The composition according to any one of the preceding claims, wherein, Based on the number of isocyanate reactive groups and free radical curing groups in the hybrid compound (B1), the average functionality of the hybrid compound (B1) is at least three.

7. The composition according to any one of the preceding claims, wherein, The molecular weight of the hybrid compound (B1) is in the range of 400 g / mol to 20,000 g / mol, more preferably 500 g / mol to 19,000 g / mol, and particularly preferably 600 g / mol to 18,000 g / mol.

8. The composition according to any one of the preceding claims, wherein, The second initiator (C2) is selected from peroxides and / or benzinolide.

9. The composition according to any one of the preceding claims, wherein, Each of the curable compositions comprises the following components, based on the total weight of the curable composition: (A) 1 wt.% to 40 wt.% of the said at least bifunctional, passivated solid isocyanate, (B) 5 wt.% to 90 wt.% of the isocyanate reactive component, (C) 0.01 wt.% to 5 wt.% of the first initiator (C1) and 0.01 wt.% to 10 wt.% of the second initiator (C2). (D) 0 wt.% to 50 wt.% of further free radical-curable components, and (E) 0 wt.% to 80 wt.% of additives (E).

10. A method for bonding, casting, and / or coating a substrate using a curable composition according to any one of the preceding claims, the method comprising the steps of: a) Applying the curable composition to a first substrate; b) Optionally, a second substrate is provided, thereby forming a substrate composite; c) Fixing the curable composition using photochemical radiation; as well as d) The fixed composition on the substrate or in the substrate composite is thermocured by heating to a temperature of at least 60°C.

11. Use of the curable composition according to any one of claims 1-9 for bonding, casting and / or adhesiveling of electronic and optoelectronic components, particularly for use in the manufacture of camera modules or LIDAR systems.

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