Curable composition based on thiol-curing epoxides and use for bonding, potting, sealing and / or coating

Abstract

An actinic radiation-setting and heat-curable composition comprises: (A) an epoxy-containing compound; (B) a thiol; (C) a nitrogen-containing compound as accelerator; (D) a radically curable component comprising a (meth)acrylate (D1), wherein the (meth)acrylate (D1) is at least difunctional; (E) a radical photoinitiator; and (F) a stabilizer. The thiol (B) comprises tris(3-mercaptopropyl)isocyanurate, the ratio of the epoxy groups of component (A) to the radically curable groups of component (D) is in the range of 0.015 to 0.250, and the (meth)acrylate (D1) has an equivalent weight of at least 100.0 g / mol.

Description

[0001] DELO Industrial Adhesives GmbH & Co. KGaA

[0002] Our reference number: D 3405 WO

[0003] WS / TH

[0004] Curable compound based on thiol-curing epoxies and used for bonding, potting, sealing and / or coating.

[0005] AREA OF INVENTION

[0006] The invention relates to a mass based on thiol-curing epoxides that can be fixed by actinic radiation and hardened by heat.

[0007] Furthermore, the invention relates to the use of the mass for bonding, potting, sealing and / or coating substrates.

[0008] TECHNICAL BACKGROUND

[0009] In the field of adhesive technology, there is a growing need for very short curing times to achieve high cycle rates. Light-curing adhesives offer one solution. However, the substrates must be sufficiently translucent to allow the adhesives to cure uniformly and with minimal stress under light exposure. Other curing mechanisms, such as heat or moisture, are significantly slower, and fast curing speeds are often accompanied by drastically reduced processing times.

[0010] Dual-curing adhesives offer an alternative, combining the advantages of rapid light curing with a second curing mechanism. For example, irradiating fillet welds allows for quick fixation of the components, which can then be held in position without further mechanical support. Light curing drastically reduces the time required for a component to be processed further. The second curing mechanism ensures final curing and guarantees the permanent mechanical strength and chemical resistance of the adhesive bond. This final curing can also take place separately from the light curing, both in time and space. Crucially, this requires the formation of a highly homogeneous network. In other words, the network formed during dark curing should not differ significantly from the network formed during light curing.

[0011] For this purpose, epoxy-thiol systems can be advantageously equipped with light-curing capability. The heat-curing adhesive is typically combined with a (meth)acrylate component and a photoinitiator. Such resins also have the advantage that heat curing can be accelerated by adding an amine component, thus enabling the bonding or potting of temperature-sensitive substrates. Application areas range from electronics manufacturing and medical technology to optics and the automotive industry.

[0012] WO 2005 / 052021 A1 discloses a one-component compound comprising, in addition to an epoxy resin, a latent curing accelerator, and at least a difunctional thiol, a radiation-curable compound based on a (meth)acrylate and a photoinitiator. The proportion of the thiol component is limited to a maximum of 5 wt.% to achieve a sufficient processing time.

[0013] WO 2016 / 143777 A1 describes the challenges encountered in the formulation of thiol-containing compounds intended for UV curing. The high reactivity of thiols and acrylate-containing components leads to significantly shortened processing times, preventing the use of these compounds as adhesives. This problem is solved within the scope of the cited invention by the addition of a thiol hardener based on glycolurils. The described thiol hardeners are also free of hydrolysis-sensitive ester groups and are particularly suitable for increasing the moisture resistance of the cured compounds. Further formulation examples based on glycoluril derivatives can be found in WO 2016 / 143815 A1.

[0014] Dual-curing formulations based on ester-free thiol hardeners are also described in WO 2018 / 047849 A1 and WO 2023 / 065802 A1.

[0015] Dual-curing compounds are particularly well-suited for fixing precisely aligned components during the assembly of camera modules and for subsequent curing. The avoidance of stray light is an important quality characteristic in this context. EP 4 317 234 A1 discloses dual-curing epoxy-thiol compounds for this purpose, which require a minimum amount of an epoxy-containing component to produce matte surfaces during heat curing.

[0016] EP 3 724 253 B1 describes dual-curing compounds that require low temperatures for heat curing and simultaneously offer working times of up to several days at room temperature. These properties are achieved, among other things, through a special stabilizer combination consisting of a sulfonyl isocyanate and an acid.

[0017] Further dual-curing formulations can also be found in WO 2023 / 286699 A1 and WO 2023 / 286700 A1.

[0018] Current developments are placing ever-increasing demands on cycle times, requiring continuous optimization of fixing speeds and strengths, while maintaining moderate curing temperatures and long processing times. The materials disclosed in the prior art are not suitable for meeting these increasing demands.

[0019] SUMMARY OF THE INVENTION

[0020] One object of the present invention is to avoid the disadvantages of compositions known from the prior art and to provide masses, in particular single-component masses, that can be fixed by actinic radiation and cured by heat and are characterized by rapid light fixation and high light fixation strength combined with long processing times.

[0021] The object of the invention is further to provide masses that harden at low temperatures and are therefore suitable for joining, potting, sealing and / or coating particularly temperature-sensitive components, especially optoelectronic components and parts.

[0022] This problem is solved according to the invention by a mass that can be fixed by actinic radiation and hardened by heat according to claim 1.

[0023] Advantageous embodiments are specified in the dependent claims, which can be optionally combined with one another. The mass according to the invention, which can be fixed by actinic radiation and hardened by heat, comprises:

[0024] (A) an epoxy-containing compound;

[0025] (B) a thiol;

[0026] (C) a nitrogen-containing compound as an accelerator;

[0027] (D) a radically curable component comprising a (meth)acrylate (D1) wherein the (meth)acrylate (D1) is at least difunctional;

[0028] (E) a radical photoinitiator; and

[0029] (F) a stabilizer. characterized in that the thiol (B) comprises tris(3-mercaptopropyl)isocyanurate, the ratio of the epoxide groups of component (A) to the radically curable groups of component (D) is in the range of 0.015 and 0.250, and the (meth)acrylate (D1) has an equivalent weight of at least 100.0 g / mol.

[0030] The composition according to the invention is liquid at room temperature and can be fixed in a short time by irradiation with light or actinic radiation. This leads to the activation of the radical photoinitiator (E) and consequently to the crosslinking of the (meth)acrylate (D1) and other radically curable components, including the thiol (B). The composition and / or bond rapidly acquires an initial strength through irradiation, which enables temporally and / or spatially decoupled final curing.

[0031] Finally, the adhesive is cured at moderate temperatures by applying suitable heat. The low curing temperatures are made possible in particular by the selection and mixing of components (A) to (C).

[0032] The particularly well-balanced ratio of epoxy groups and radically curable groups in the corresponding components (A) and (D) of the curable mass according to the invention enables an optimal compromise between rapid light fixation, low curing temperatures, and long processing time. According to the invention, the ratio of epoxy groups in component (A) to radically curable groups in component (D) is therefore in the range of 0.015 to 0.250.

[0033] In this context, the focus is on the total number of each functional group in the mass, which depends both on the functionality of the individual compounds of the respective component and on the proportion of the respective component in the total mass. Furthermore, it is understood that only reactive functional groups are considered in the calculation of the ratio, i.e., those functional groups that can participate in the crosslinking reaction.

[0034] In particular, the low curing temperature and / or time, the long processing time, and the high light-fixability can be achieved and influenced by the relative content of epoxy groups in component (A) compared to the radically curable groups in component (D). Thus, a decrease in curing temperature and / or time can be observed with increasing content of epoxy groups in component (A); however, conversely, an increasing content of epoxy groups also leads to a faster increase in the viscosity of the curable mass during room temperature storage and to lower light-fixability.

[0035] In this way, it is also achieved that the mass according to the invention can be formulated as a single component, since a sufficiently long processing time can be ensured.

[0036] The use of a (meth)acrylate (D1) with an equivalent weight of at least 100.0 g / mol further ensures that the composition according to the invention exhibits both rapid light fixation with rapid strength development and excellent mechanical properties after curing. In addition, the influence of the epoxy-containing compound (A) on the processing time can be reduced, so that the composition according to the invention is particularly stable in storage, especially as a one-component composition.

[0037] The equivalent weight is defined as the ratio of the molecular weight of the respective compound to the number of the respective functional groups in that compound. For example, a difunctional (meth)acrylate with a molecular weight of 300.0 g / mol has an equivalent weight of 150.0 g / mol. In the case of a mixture of several (meth)acrylates (D1), according to the invention, each of the contained (meth)acrylates (D1) has a corresponding equivalent weight.

[0038] Furthermore, it has been shown that ester-free and highly functional thiols, in particular, have a particularly advantageous effect on the aforementioned properties of the curable and cured compounds. According to the invention, component (B) therefore comprises tris(3-mercaptopropyl)isocyanurate, which has proven to be particularly advantageous in combination with the inventive ratio of epoxy and radically curable groups in order to obtain compounds with the desired property profile.

[0039] The invention further relates to the use of the composition according to the invention as described above as an adhesive or sealant for bonding, potting, sealing and / or coating substrates, in particular optical, electronic and / or optoelectronic components.

[0040] DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS

[0041] The invention is described in detail below, using examples of preferred embodiments, which, however, should not be understood in a limiting sense. The following definitions are used in the description:

[0042] “Single-component” or “single-component mass” means, within the meaning of the invention, that the aforementioned components of the mass are present together in a single packaging unit.

[0043] The masses are considered "processable" if the viscosity of the respective finished mixed mass changes by less than 25% during storage at room temperature over a period of 7 days.

[0044] For the purposes 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. "At least difunctional" means that each molecule contains two or more units of the respective functional group mentioned.

[0045] Insofar as the indefinite article “ein” or “eine” is used, this also includes the plural form “ein oder mehr”, unless this is expressly excluded.

[0046] In the context of the inventive method, “fixation” or “fixing” refers to the development of a strength of the mass from which no further flow of the mass can occur, or the degree of strength from which joined parts, in particular substrates, can be handled in subsequent processes without the adhesive bond, in particular a substrate bond, being destroyed.

[0047] "Complete hardening" or "final hardening" refers to a state at which the maximum strength development of the material is complete. This means that the mechanical properties of the material essentially no longer change. In particular, the residual enthalpy of the hardened material is less than 5% in the isothermal DSC measurement at 80 °C.

[0048] All weight percentages listed below refer to the total weight of components (A) to (F), unless otherwise stated.

[0049] The individual components of the hardenable mass are described in more detail below.

[0050] Component (A): Epoxy-containing compound

[0051] The curable mass comprises at least one epoxy-containing compound (A).

[0052] The addition of an epoxy (A) results in a sharp curing behavior during hot curing, and complete curing occurs at moderate temperatures below 140 °C, for example, at 120 °C or lower. Without the addition of an epoxy (A), the final curing of the compound is only achieved at high temperatures, which can damage heat-sensitive components or substrates. The epoxy (A) is not further restricted in its chemical structure and can comprise aromatic and / or aliphatic compounds with at least one epoxy group in the molecule, such as cycloaliphatic epoxides, glycidyl ethers, glycidylamines, and mixtures thereof.

[0053] The epoxy (A) can be mono- or higher-functional.

[0054] Preferably, the epoxy (A) comprises at least one di- or higher-functional epoxy. In this way, the epoxy (A) contributes to the crosslinking and thus the mechanical stability of the hardened mass.

[0055] Examples of monofunctional epoxides (A) include butyl glycidyl ether, (2-ethylhexyl) glycidyl ether, phenyl glycidyl ether, 2,3-epoxypropyl o-tolyl ether, 4-tert-butylphenyl glycidyl ether, styrene oxide, α-pinene oxide, cresol glycidyl ether, polyethylene glycol monoglycidyl ether, polypropylene glycol monoglycidyl ether, polytetramethylene monoglycidyl ether, fatty acid glycidyl ester, norbornene oxide, glycidyl ether of cardanol, and glycidyl neodecanoate.

[0056] Cycloaliphatic epoxides (A) are known in the prior art and include compounds that bear both a cycloaliphatic group and an oxirane ring.

[0057] Examples include 3-cyclohexenylmethyl-3-cyclohexylcarboxylate diepoxide, 3,4-epoxycyclohexylalkyl-3',4'-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3',4'-epoxy-6-methylcyclohexanecarboxylate, vinylcyclohexene dioxide, bis(3,4-

[0058] Epoxycyclohexylmethyl)adipate, dicyclopentadiene dioxide, 1,2-epoxy-6-(2,3-epoxypropoxy)hexahydro-4,7-methanindane. Other suitable cycloaliphatic epoxides can be found in US 9212188 B2, US 10 464943 B2, or US 10 961345 B2.

[0059] Preferably, the epoxy-containing compound (A) comprises an aromatic epoxide. Examples of aromatic epoxides (A) are bisphenol-A epoxy resins, bisphenol-F epoxy resins, phenol-novolac epoxy resins, cresol-novolac epoxy resins, biphenyl epoxy resins, 4,4'-biphenyl epoxy resins, divinylbenzene dioxide, 2-glycidyl phenyl glycidyl ethers, naphthalenediol diglycidyl ethers, glycidyl ethers of tris(hydroxyphenyl)methane, and glycidyl ethers of tris(hydroxyphenyl)ethane. Furthermore, all fully or partially hydrogenated analogues of aromatic epoxides (A) can also be used. Preferably, low-halogen or halogen-free bisphenol-A and bisphenol-F epoxy resins are used. A low-halogen epoxy resin is understood to be an epoxy resin that has a residual halogen content due to unavoidable impurities. Such impurities originate, for example, from synthesis residues when using epichlorohydrin to synthesize a glycidyl ether for the production of epoxy resins.

[0060] The epoxide-containing compound (A) can be an aromatic epoxide or a mixture of several aromatic epoxides.

[0061] Isocyanurates substituted with epoxide-containing groups and other heterocyclic compounds can also be used as component (A) in the composition according to the invention. Triglycidyl isocyanurate and monoallyldiglycidyl isocyanurate are examples.

[0062] Furthermore, bio-based epoxides (A) can be used in the composition according to the invention. These include, for example, all bio-based analogues of the aforementioned epoxides (A). Further examples of bio-based epoxides (A) are isosorbide-based epoxides, which are commercially available from Kukdo under the names KDBM-1010 and KDBM-1040. Cardanol-based epoxides can also be used. Suitable examples are known from Cardolite under the trade names Cardolite NC-514, Cardolite NC-547, or Cardolite Ultra Lite 513.

[0063] Furthermore, polyfunctional epoxy resins of all the resin groups mentioned, tough elasticized epoxy resins and mixtures of different epoxy compounds can also be used in the mass according to the invention.

[0064] A combination of several epoxy-containing compounds is also within the scope of the invention.

[0065] Suitable epoxies (A) are commercially available under the trade names CELLOXIDE™ 2021 P, CELLOXIDE™ 8000 from Daicel Corporation, Japan; EPIKOTE™ RESIN 828 LVEL, EPI KOTE™ RESIN 166, EPI KOTE™ RESIN 169 from Westlake Epoxy BV, Netherlands; Epilox™ resins of product lines A, T and AF from Leuna Harze, Germany; or EPICLON™ 840, 840-S, 850, 850-S, EXA850CRP, 850-LC from DIC KK, Japan. Adding higher proportions of the epoxy (A) relative to component (D) can further reduce the curing temperature and / or time. However, excessively high relative proportions of component (A) lead to decreased light-curing strengths and shorter processing times. Therefore, according to the invention, the ratio of the epoxy groups of component (A) to the radically curable groups of component (D) is in the range of 0.015 to 0.250.

[0066] For example, the ratio of the epoxy groups of component (A) to the radically curable groups of component (D) is in the range of 0.020 to 0.225, preferably in the range of 0.025 to 0.200.

[0067] In order to achieve high light fixation strength with sufficiently long processing times, the epoxy-containing compound (A) can have an equivalent weight of at most 300 g / mol, preferably at most 250 g / mol.

[0068] The equivalent weight can be calculated based on the molecular mass and the functionalities present, determined experimentally, or obtained from data sheets of commercially available epoxides (A).

[0069] Due to the comparatively smaller proportion of component (A) compared to the radically curable component (D), component (A) has a smaller volume fraction in the total volume of the mass than the radically curable component (D).

[0070] Component (A) is present in the mass according to the invention in a proportion of 0.5 to 15 wt.%, preferably in a proportion of 0.5 to 12 or 1 to 12 wt.%, in each case based on the total weight of components (A) to (F).

[0071] Component (B): Thiol

[0072] The thiol (B) serves as a hardener in the mass according to the invention.

[0073] It has been shown that tris(3-mercaptopropyl)isocyanurate, as the thiol (B), ensures rapid and high light fixation as well as a long processing time and can therefore be used particularly advantageously to solve the problem of the present invention. The thiol (B) therefore comprises tris(3-mercaptopropyl)isocyanurate.

[0074] In the curable mass according to the invention, the thiol (B) can comprise at least 70 wt.%, preferably at least 80 wt.%, further preferably at least 85 wt.%, particularly preferably at least 90 wt.% tris(3-mercaptopropyl)isocyanurate, in each case based on the total weight of component (B).

[0075] The thiol (B) can consist of tris(3-mercaptopropyl)isocyanurate.

[0076] The addition of further thiols (B) is also in accordance with the invention. These can be 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, biaryls, diaryls, glycoluril and combinations thereof.

[0077] Examples of commercially available ester-based thiols based on 2-mercaptoacetic acid include pentaerythritoltetramercaptoacetate and glycol dimercaptoacetate, available under the brand names Thiocure™ 140 and 120 from Bruno Bock, Germany.

[0078] 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, which are available under the brand names Thiocure™ 330, 340, 320 and 331 from Bruno Bock, Germany.

[0079] Examples of commercially available thioethers include DMDO (1,8-dimercapto-3,6-dioxaoctane), available from Arkema SA, France, DMDS (dimercaptodiethyl sulfide) and DMPT (2,3-di((2-mercaptoethyl)thio)-1-propanethiol), both available from Bruno Bock, Germany.

[0080] With regard to increased durability of the cured mass, the use of ester-free thiols in component (B) is particularly preferred. Examples of ester-free thiols can be found in JP 2012 153 794 A, which is incorporated into this description by reference.

[0081] US Patent 11 807596 B2 describes ester-free thiol hardeners with a dithioacetal backbone, which can also be advantageously used in the masses according to the invention.

[0082] Other ester-free polythiols, as disclosed in WO 2023 / 065802 A1 and suitable for use in the composition according to the invention, can be synthesized, for example, starting from 5,5'-diallyl-2,2'-dihydroxybiphenyl (magnolol).

[0083] Ester-free thiols based on a glycoluril compound are known from EP 3 075 736 A1. These can also be used as component (B) in the composition according to the invention.

[0084] Higher-functional thiols, which can be obtained, for example, by oxidative dimerization processes of at least difunctional thiols, can also be used in component (B).

[0085] Monofunctional thiols can also be advantageously used as thiol (B) in the curable mass.

[0086] The preceding list should be seen as exemplary and not exhaustive.

[0087] The proportion of thiol (B) in the mass according to the invention can be from 15 to 70 wt.%, preferably from 25 to 55 wt.%, in each case based on the total weight of components (A) to (F).

[0088] Component (C): Accelerator

[0089] The composition according to the invention contains as a further component (C) a nitrogen-containing compound as an accelerator for hardening. The hardening behavior of the composition can be further adjusted by the type and concentration of the accelerator in the hardenable composition.

[0090] A mixture of two or more nitrogen-containing compounds can also be used as a latent accelerator. Preferably, the accelerator is a heat-latent accelerator that is activated by heating to the temperature of the heat curing process and releases a basic compound.

[0091] Both solid and liquid accelerators can be used.

[0092] Suitable accelerators include all compounds that are also known as latent hardeners for epoxy compounds and that, at the activation temperatures, are suitable for addition crosslinking with the epoxy compound.

[0093] The accelerator is preferably in solid form at room temperature and dispersed in the composition.

[0094] Furthermore, heat-latent liquid accelerators can also be used, in particular liquid accelerators with blocked amine groups that are converted into the free amine compound upon heating.

[0095] Preferably, the accelerator is a nitrogen-containing compound selected from the group of amines, ureas, imidazoles, triazine derivatives, polyamidoamines and / or guanidines.

[0096] Furthermore, adducts and / or reaction products of epoxides or isocyanates with the aforementioned nitrogen compounds can be used as accelerators, in particular reaction products with amines as already described in US 5 430112 A.

[0097] Examples of commercially available accelerators include Ajicure PN-H, Ajicure MY-24, Ajicure MY-25, Ajicure PN-23 (available from Ajinomoto Co., Inc., Tokyo, Japan); Fujicure FXR1081, FXR1020, FXR1030 (available from Sanho Chemical Co. Ltd.); Aradur 9506 (available from Huntsman International LLC.); Ancamine 2014 FG and Ancamine 2442 (available from Evonik Degussa GmbH); Adeka Hardener EH-5057PK, Adeka Hardener EH-5046S, Adeka Hardener EH-5030S, Adeka Hardener EH-5011S, Adeka Hardener EH-4356S (available from ADEKA Europe GmbH) and Curezol (available from Shikoku Chemicals Corporation).

[0098] The accelerators can also be encapsulated. Examples of commercially available products include Technicure® LC-80 and Technicure® LC-100 from ACCI Speciality Materials. Other commercial products are available under the Novacure brand from Asahi-Kasei. Examples of commercially available products include HX-3613, HX-3722, HX-3741, HX-3742, HX-3088, HX-3921 HP, HX-3922 HP, HX-3941 HP, HXA-3932 HP, HXA-5911 HP, HXA-9322 HP, and HXA-9382 HP.

[0099] In addition to using the aforementioned compounds, photolatent bases can also be employed. Examples of possible substance classes include 4-(ortho-nitrophenyl)-dihydropyridine, quaternary organoboron compounds, alpha-aminoacetophenones, and amines blocked with photolatent groups. These can release basic compounds upon actinic radiation and thus also act as accelerators.

[0100] In the mass according to the invention, the accelerator (C) can be present in a proportion of 0.5 wt.% to 30 wt.%, preferably in a proportion of 2 to 10 wt.%, in each case based on the total weight of the components (A) to (F).

[0101] Component (D): Radically curable component

[0102] The mass according to the invention further comprises a radically curable component (D) comprising a (meth)acrylate (D1), wherein the (meth)acrylate (D1) is at least difunctional and has an equivalent weight of at least 100.0 g / mol.

[0103] The equivalent weight can be calculated based on the molecular mass and the functionalities present, determined experimentally, or obtained from data sheets of commercially available (meth)acrylates (D1).

[0104] The term “(meth)acrylates” here and in the following refers to both the derivatives of acrylic acid and methacrylic acid, as well as combinations and mixtures thereof.

[0105] To further increase the light-fix strength of the compound, the (meth)acrylate (D1) can have a homopolymerization glass transition temperature (homopolymerization Tg) of 60 °C or higher. (Meth)acrylates (D1) with a homopolymerization glass transition temperature of less than 60 °C are more flexible and exhibit reduced adhesion during light curing.

[0106] The homopolymerization glass transition temperature of a given (meth)acrylate as a monomer refers to the glass transition temperature of a homopolymer of that monomer. The homopolymer must have a sufficiently high molecular weight so that its glass transition temperature reaches a limit. It is generally known that the glass transition temperature of a homopolymer increases with increasing molecular weight up to a certain limit. Furthermore, the homopolymer must be essentially free of moisture, residual monomer, solvents, and other impurities that could affect the glass transition temperature.

[0107] The homopolymer of the respective monomer can be obtained by adding a thermal initiator and subsequent heat curing, or alternatively by adding a photoinitiator and curing using light.

[0108] The glass transition temperature of the homopolymer can then be measured, for example using differential scanning calorimetry (DSC) or mechanical analysis (DMA). Of these two methods, values ​​obtained from DSC measurements are preferred.

[0109] Furthermore, the homopolymerization glass transition temperature is usually available as a material property in data sheets provided by the commercial suppliers of the respective (meth)acrylate.

[0110] The (meth)acrylate (D1) exists in a di- or higher-functional state and is not further structurally restricted.

[0111] Both aliphatic and aromatic (meth)acrylates (D1) can be used.

[0112] Suitable examples include the following (meth)acrylates (D1): tricyclodecanedimethanol diacrylate, di(trimethylolpropane tetraacrylate), dioxane glycol diacrylate (DOGDA), ethoxylated bisphenol A diacrylate, tris[2-(acryloyloxy)ethyl]isocyanurate, 9,9-bis[4-(2-acryloyloxyethyloxy)phenyl]fluorene, di(pentaerythritol pentaacrylate), urethane acrylates of monomeric, oligomeric, or polymeric diols and polyols, and dipentaerythritol hexaacrylate (DPHA), and combinations thereof. Higher-functionality (meth)acrylates (D1) derived from multiply branched or dendrimeric alcohols can also be advantageously used. Suitable (meth)acrylates (D1) are available, for example, from Arkema France, IGM Resins, or Miwon Europe.

[0113] A combination of several (meth)acrylates (D1) is also within the scope of the invention.

[0114] To further improve light fixation strength, the (meth)acrylate (D1) can be an acrylate.

[0115] The radically curable component (D) can consist of the (meth)acrylate (D1).

[0116] The proportion of the radically curable compound (D) comprising the (meth)acrylate (D1) in the curable mass according to the invention can be from 20 to 80 wt.%, preferably from 40 to 65 wt.%, in each case based on the total weight of the components (A) to (F).

[0117] (D2): Ethylene unsaturated compound

[0118] The radically curable component (D) may further contain another ethylene unsaturated compound (D2) that is different from the (meth)acrylate (D1).

[0119] The ethylene unsaturated compound (D2) is not further restricted structurally as long as it contains a radically hardenable ethylene unsaturated double or triple bond.

[0120] The ethylene unsaturated compound (D2) can exist in a mono- or higher-functional state.

[0121] Suitable examples include bismaleimides, allyl and methallyl compounds, such as 1,3,5-triallyl-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, which is commercially available as TAICROS®, isoprenes, butadienes, propargyls, and vinyl compounds, including N-vinyl compounds such as vinylmethyloxazolidinone (VMOX), N-vinylcaprolactam, N-vinylpyrrolidone, and N-vinylimidazole.

[0122] Unhydrogenated polybutadienes with free double bonds, such as the polyBD(β) types, can also be used as ethylene-unsaturated compounds (D2). A combination of several ethylene-unsaturated compounds (D2) is also within the scope of the invention.

[0123] Higher molecular weight ethylene unsaturated compounds (D2) can also include urethane(meth)acrylates based on polyesters, polyethers, polycarbonate diols and / or (hydrogenated) polybutadiene diols.

[0124] Monofunctional (meth)acrylates can also be advantageously used as ethylene-unsaturated compounds (D2). Examples of monofunctional (meth)acrylates are isobornyl(meth)acrylate, isononyl(meth)acrylate, 2-propylheptyl(meth)acrylate, and 4-methyl-2-propylhexyl(meth)acrylate.

[0125] Pentadecyl (meth) acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, trimethylolpropane formyl (meth) acrylate,

[0126] Cyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate,

[0127] 3,3,5-Trimethylcyclohexanol (meth)acrylate, behenyl (meth)acrylate,

[0128] 2-Methoxyethyl (meth) acrylate and other mono- or poly-alkoxylated alkyl (meth) acrylates, isobutyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, tricyclecyl (meth) acrylate, isostearyl (meth) acrylate,

[0129] 2-(o-Phenylphenoxy)ethyl (meth)acrylate, (meth)acryloylmorpholine and N,N-dimethyl (meth)acrylamide.

[0130] Furthermore, admixtures of at least difunctional (meth)acrylates as component (D2) are possible, whose homopolymerization glass transition temperature is less than 60 °C. Examples include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, glycerol propoxylate tri(meth)acrylate, polyethylene glycol- and polypropylene-based (meth)acrylates.

[0131] Furthermore, hybrid compounds which, in addition to at least one epoxy function, have at least one (meth)acrylate function, can be advantageously used in the curable mass.

[0132] The proportion of the ethylene-unsaturated compound (D2) is in particular at most 20 wt.%, preferably at most 10 wt.%, in each case based on the total weight of component (D). It is understood that, within the scope of the invention, in addition to the radically curable groups of the (meth)acrylate (D1), radically curable ethylene-unsaturated groups of the ethylene-unsaturated compound (D2), if present, as well as epoxide groups of the hybrid compounds of component (D2), are also included in the ratio of the epoxide groups of component (A) to the radically curable groups of component (D).

[0133] Component (E): Radical photoinitiator

[0134] The curable mass also includes a radical photoinitiator (E).

[0135] The radical photoinitiator (E) enables light fixation of the curable mass using the radically curable component (D) which comprises a (meth)acrylate (D1).

[0136] In addition to component (D), other radically curable formulation components can also be incorporated into the light-fixing network. For example, the reaction of thiol (B) with component (D) using a photoinitiator (E) is possible via a radical mechanism. Furthermore, the amount of thiol (B) available for the addition reaction can thus be advantageously controlled via the light reaction.

[0137] Any common, commercially available compound can be used as a photoinitiator (E), such as α-hydroxyketones, benzophenone, α,α'-diethoxyacetophenone, 4,4-diethylaminobenzophenone, 2,2-dimethoxy-2-phenylacetophenone, 4-isopropylphenyl-2-hydroxy-2-propylketone, 1-hydroxycyclohexylphenylketone, isoamyl para-dimethylaminobenzoate, methyl 4-dimethylaminobenzoate, methyl orthobenzoylbenzoate, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-hydroxy-2-methyl-1-phenylpropan-1-one.

[0138] 2-isopropylthioxanthone, dibenzosuberone, 2,4,6-trimethylbenzoyl diphenylphosphine oxide and bisacylphosphine oxides, wherein the aforementioned compounds can be used alone or in combination of two or more of the aforementioned compounds as a photoinitiator (E).

[0139] The Omnirad™ types from IGM Resins can be used as photoinitiators (E) that can be activated by UV radiation, for example the types Omnirad 184, Omnirad 500, Omnirad 1173, Omnirad 2959, Omnirad 754, Omnirad BDK, Omnirad 369, Omnirad 907, Omnirad 2022, Omnirad 2100, Omnirad 784, Omnirad TPO, Omnirad TPO-L, Omnirad 819, Omnirad 819 DW, Omnirad MBF, Omnirad BMS, Omnirad 4265.

[0140] The preceding lists are to be seen as examples for the photoinitiator (E) and are by no means to be understood as limiting.

[0141] The photoinitiator used as component (E) in the masses according to the invention is preferably activatable by actinic radiation of a wavelength of 200 to 400 nm, particularly preferably of 250 to 365 nm.

[0142] If necessary, the photoinitiator (E) can be combined with a suitable sensitizing agent, which is added as an additive.

[0143] The photoinitiator (E) is present in the masses in a proportion of 0.01 to 5 wt.%, preferably 0.5 to 3 wt.%, in each case based on the total weight of components (A) to (F).

[0144] Component (F): Stabilizer

[0145] The hardenable mass for use in the process according to the invention further comprises a stabilizer (F). The addition of the stabilizer (F) can, for example, improve storage stability and processing time.

[0146] Numerous stabilizers (F) are known in the prior art; for example, boric acids or aluminum chelates can be used. Sulfonyl isocyanates and organic acids can also be used alone or as a stabilizer mixture, as described in WO 2019 / 115203 A1.

[0147] Furthermore, aluminates, titanates, zirconium esters and isocyanates, as described in CN 110 054 760 B, can be used as stabilizers (F).

[0148] The use of a stabilizer (F) makes it possible to ensure a processing time of at least 72 h, preferably at least 168 h, for the curable masses at room temperature. Boric acids as component (F) can contain linear, branched, and cyclic alkyl groups and / or aromatic groups.

[0149] Examples of boric acids are trimethyl borate, triethyl borate, tri-n-propyl borate, triisopropyl borate, tri-n-butyl borate, tris-(2-ethylhexyl) borate, tricyclohexyl borate, 2,2'-oxybis(5,5-dimethyl-1,3,2-dioxaborolane), triphenyl borate, tribenzyl borate, tri-ortho-tolyl borate, tri-meta-tolyl borate and triethanolamine borate.

[0150] An example of an aluminum chelate is aluminum tris-acetylacetonate.

[0151] Sulfonyl isocyanates used as component (F) can be bound to an aliphatic or aromatic residue.

[0152] The aliphatic sulfonyl isocyanate can comprise a linear or branched alkyl group with 1 to 18 carbon atoms, preferably with 4 to 8 carbon atoms.

[0153] Preferably, the sulfonyl isocyanate comprises an aromatic sulfonyl isocyanate, particularly preferably a monofunctional arylsulfonyl isocyanate. The aryl group can optionally be an alkyl-substituted or unsubstituted phenyl, naphthyl, or biphenyl group.

[0154] The sulfonyl isocyanate particularly preferably comprises para-toluenesulfonyl isocyanate.

[0155] In principle, any acidic compound capable of transferring protons can be used as an organic acid. Preferably, the acid has a pKa value of 12 or less, particularly preferably 10 or less. In particular, the pKa value of the acid is below the pKa value of the corresponding acid of the latent accelerator (C).

[0156] Suitable acids include, for example, tannic acid, propyl gallate, barbituric acid, 3,4-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid, emboic acid, citric acid, phenylboronic acid, meldric acid, phloroglucinol, fumaric acid, ascorbic acid, salicylic acid, 3,4-dihydroxycinnamic acid, quinone derivatives of enolizable acids, mercaptic acids, acid anhydrides, acidic phenols, and / or organophosphoric acids. The foregoing list is to be considered exemplary only and is not exhaustive. More preferably, the acid comprises or consists of an acidic phenol with a pKa value of 9.0 or less. Particularly preferably, the acid comprises pyrogallol, alone or in a mixture with another acidic phenol and / or one of the other aforementioned acids.

[0157] Furthermore, radical scavengers such as hindered phenols and hindered amines, phosphites, thioethers or triazines can be used as stabilizers (F).

[0158] Examples of sterically hindered phenols are 2,4-di-tert-butylphenol, 2,6-di-tert-butylphenol, 2-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-methylphenol,

[0159] 2.4.6-T ritert-butylphenol, 2,4,6-T rimethylphenol, 2,6-Di-tert-butyl-4-methylphenol,

[0160] 2,6-Di-tert-butyl-4-ethylphenol, 4,4'-Methylenebis(2,6-di-tert-butylphenol), 3,5-Di-tert-butyl-4-hydroxybenzyl alcohol, 3,5-Di-tert-butylcatechol, 2,2-Methylenebis(4-methyl-6-tert-butylphenol), 6-tert-Butyl-2,4-xylenol, (Ethane-1,2-diylbis(oxy))bis(ethane-2,1-diyl) bis(3-(3-(tert-butyl)-4-hydroxy-5-methylphenyl)propanoate) (Irganox 245), Pentaerythrityl tetrakis (3-(3,5-bis(1, 1 - dimethylethyl)-4-hydroxyphenyl) propionate) (Irganox 1010), octyl-3,5-di-tert-butyl- 4-hydroxy-hydrocinnamate (Irganox 1135), 3-(3,5-ditert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoyl]propanohydrazide (Irganox MD 1024), 2-methyl-4,6-bis(octylsulfanylmethyl)phenol (Irganox 1250L) and 2,4-bis(dodecylthiomethyl)-6-methylphenol (Irganox 1726).

[0161] Furthermore, quinones and hydroquinones, including for example 4-methoxyphenol (MEHQ), can be used as stabilizers (F).

[0162] In the mass according to the invention, the stabilizer (F) can be present in a proportion of 0.01 wt.% to 2 wt.%, preferably in a proportion of 0.05 wt.%, in each case based on the total weight of the components (A) to (F).

[0163] Component (G): Additives

[0164] In addition to components (A) to (F), the composition according to the invention may contain further additives (G). Examples, but not limited to, sensitizing agents, catalysts, toughness modifiers such as core-shell particles or block copolymers, antioxidants, dyes, pigments, fluorescent agents, thixotropic agents, thickeners, thermostabilizers, antioxidants, plasticizers, fillers, flame retardants, inductively heatable particles, thermally and / or electrically conductive particles, corrosion inhibitors, water scavengers, diluents, leveling and wetting additives, adhesion promoters, and combinations thereof, which may be used as additives (G), are listed.

[0165] The additives (G) are present in the curable mass in a proportion of up to 80 wt.%, preferably in a proportion of up to 50 wt.%, based on the total weight of the curable mass.

[0166] Formulation of the hardenable mass

[0167] One formulation of the mass according to the invention comprises the components (A) to (F) described above.

[0168] Preferably the mass comprises or consists of the following components, each based on the total weight of components (A) to (F):

[0169] (A) 0.5 to 15 wt% of the epoxy-containing compound,

[0170] (B) 15 to 70 wt.% of the thiol comprising tris(3-mercaptopropyl)isocyanurate,

[0171] (C) 0.5 to 30 wt.% of the nitrogen-containing compound as a latent accelerator,

[0172] (D) 20 to 80 wt.% of the radically curable component (D) comprising the at least difunctional (meth)acrylate (D1),

[0173] (E) 0.01 to 5 wt% of the radical photoinitiator, and

[0174] (F) 0.01 to 2 wt% of the stabilizer.

[0175] According to a second embodiment, the mass preferably comprises or consists of the following components, each based on the total weight of components (A) to (F):

[0176] (A) 0.5 to 15 wt% of the epoxy-containing compound,

[0177] (B) 15 to 70 wt.% of the thiol comprising tris(3-mercaptopropyl)isocyanurate, (C) 0.5 to 30 wt.% of the nitrogenous compound as a latent accelerator comprising a mixture of two or more nitrogenous compounds as latent accelerator (C),

[0178] (D) 20 to 80 wt.% of the radically curable component (D) comprising the at least difunctional (meth)acrylate (D1),

[0179] (E) 0.01 to 5 wt% of the radical photoinitiator, and

[0180] (F) 0.01 to 2 wt% of the stabilizer.

[0181] According to a third embodiment, the mass preferably comprises or consists of the following components, each based on the total weight of components (A) to (F):

[0182] (A) 0.5 to 15 wt% of the epoxy-containing compound,

[0183] (B) 15 to 70 wt.% of the thiol comprising tris(3-mercaptopropyl)isocyanurate,

[0184] (C) 0.5 to 30 wt.% of the nitrogen-containing compound as a latent accelerator,

[0185] (D) 20 to 80 wt.% of the radically curable component (D) comprising the at least difunctional (meth)acrylate (D1) and the ethylene unsaturated compound (D2),

[0186] (E) 0.01 to 5 wt% of the radical photoinitiator, and

[0187] (F) 0.01 to 2 wt% of the stabilizer.

[0188] Optionally, the mass according to the invention can contain up to 80 wt.% of additives as component (G) in each of the aforementioned embodiments, based on the total weight of the mass.

[0189] The mass contains in particular 0.5 to 12.0 wt.% of the epoxy compound (A), based on the total weight of components (A) to (F).

[0190] It is also possible that the mass contains 40 to 80 wt.% of the radically curable component (D), based on the total weight of components (A) to (F), particularly in a proportion of more than 40 to 65 wt.%. Preferably, the mass according to the invention is a single component. Due to the specifically tailored ratio of epoxy groups of component (A) and radically curable group of component (D), as well as the use of a (meth)acrylate (D1) with an equivalent weight of at least 100.0 g / mol and of tris(3-mercaptopropyl)isocyanurate as the thiol (B), a long processing time is achieved despite the single-component formulation, thus enabling a single-component formulation.

[0191] Properties and uses of the hardenable compound

[0192] The previously described curable compound is particularly suitable for use as an adhesive or sealant for joining, potting, sealing, and / or coating substrates. This also includes bonding, molding, and / or sealing of substrates.

[0193] The composition according to the invention is particularly suitable for joining, potting, sealing and / or coating optical, electronic and / or optoelectronic components.

[0194] The use of the curable mass includes in particular the following steps: a) dosing the mass onto a first substrate; b) irradiating the mass with actinic radiation; c) optionally adding a second substrate before or after step b) to form a substrate composite, whereby the second substrate is brought into contact with the mass; and d) hot curing of the irradiated mass on the substrate.

[0195] Due to the low curing temperatures, which are sufficient for complete curing of the mass, the mass according to the invention is suitable for bonding particularly temperature-sensitive components.

[0196] Furthermore, the composition according to the invention remains workable for a period of 7 days, meaning that the viscosity change during storage at room temperature is less than 25% over this period. The composition according to the invention can be fixed in a short time using actinic radiation or light. This can be achieved with radiation intensities of 200 mW / cm². 2 For example, layer thicknesses of 100 pm can be fixed in at most 15 s, preferably at most 10 s, and most preferably at most 5 s. Light fixing times of less than 0.5 s can be achieved.

[0197] The achievable light fixation strength of the compound is typically above 1 MPa, for example 2 MPa on glass / glass.

[0198] For example, after 1 s of irradiation with light of a wavelength between 365 and 460 nm, the hardened mass can exhibit a light fixation strength of at least 2 MPa, particularly on glass / glass.

[0199] By combining light fixability with heat curing at low temperatures, the curable mass is suitable for bonding applications where temperature-sensitive substrates are bonded and short cycle times are required, such as in bonding applications for camera applications.

[0200] The cured material typically exhibits a glass transition temperature in the range of 0 to 100 °C and / or an elongation at break greater than 20%. These properties have proven particularly advantageous with regard to drop test resistance for camera components.

[0201] The mass can be hardened in a temperature range of 40 to 120 °C, preferably from 50 to 110 °C, particularly preferably from 60 to 100 °C, within a time of up to 90 min, preferably up to 60 min.

[0202] The energy input for heat curing can be via convection, for example in a convection oven, by heat conduction, for example by means of a heating plate or thermode, or by means of electromagnetic radiation, for example by means of IR radiation sources, lasers, microwaves or induction.

[0203] The heat curing can optionally be carried out at a later time than the light curing without affecting the properties of the cured mass. For this to work, the mass must be kept in the B-stage away from environmental influences such as moisture, dirt, and temperatures above room temperature. The mass according to the invention can also be activated by applying a suitable temperature and will only cure after a certain open time has elapsed. Activation can be carried out, for example, in an oven or using a flow-through activation apparatus.

[0204] Furthermore, the hardened mass achieves high levels of adhesion; for example, a compressive shear strength of at least 5 MPa, preferably at least 10 MPa, and more preferably at least 15 MPa is achieved on the substrate combination LCP / LCP (LCP for "liquid crystal polymer").

[0205] Measurement methods and definitions used

[0206] room temperature

[0207] Room temperature is defined as 23 °C ± 2 °C.

[0208] Curing

[0209] "Curing" is defined as a polymerization or addition reaction beyond the gel point. The gel point is the point at which the storage modulus G' equals the loss modulus G".

[0210] viscosity

[0211] The viscosity was measured using an Anton Paar Physica MCR 302 rheometer with a standardized PP20 measuring cone at 23 °C with a 200 pm gap and determined at a shear rate of 10 / second. To assess the processing time, the viscosity measurement was repeated after 7 days of storage at 23 °C and 50% RH (relative humidity).

[0212] DSC measurements

[0213] DSG reactivity measurements were performed in a dynamic differential calorimeter (DSC) (Mettler Toledo DSC822e or Mettler Toledo 3+) in accordance with DIN EN ISO 11357-1.

[0214] For the reaction enthalpy, 9 to 11 mg of the sample were weighed into an aluminum crucible (40 pL), sealed with a perforated lid, and subjected to a temperature of 30 to 220 °C at a heating rate of 10 K / min. The process gas was air at a flow rate of 30 mL / min. The reaction enthalpy was determined as the integral over the endothermic peak.

[0215] The final curing time was determined using an isothermal DSC measurement at 80 °C. The time until final curing was evaluated, which corresponds to the time until 95% of the reaction enthalpy has been converted.

[0216] compressive shear strength

[0217] Two LCP specimens (dimensions 20 mm × 20 mm × 5 mm) were bonded with a 5 mm overlap using the respective adhesive. The adhesive layer thickness of 0.1 mm and the overlap were adjusted using spacers and a bonding device. Heat curing was performed in a preheated convection oven at 80 °C for 60 minutes. The specimens were conditioned for 24 hours in the dark at room temperature prior to testing. Testing was carried out at room temperature on a ZwickRoell "AIIIRoundLine" testing machine at a deformation rate of 10 mm / min. The result is the mean of 5 samples.

[0218] Assessment of light fixation

[0219] Light fixation strengths were determined using a DAGE BT SERIES4000PX shear tester from Dage Semiconductor GmbH. The test procedure is based on the MIL-STD-883 method 2019.5 standard.

[0220] A glass cube (dimensions 4 mm x 4 mm x 4 mm) was bonded to a second specimen (dimensions 20 mm x 20 mm x 5 mm) made of FR4. The FR4 specimens had previously been annealed for 3 hours at 120 °C. For bonding, a drop of the curing compound was applied to the glass cube, which was then attached to the FR4 using 0.1 mm spacer wires. The bonded specimens were then irradiated for 5 seconds at a wavelength of 400 nm for a DELOLUX 20 / 400 LED lamp with an intensity of 200 mW / cm². 2 Irradiated. The exposed samples were conditioned in the dark at room temperature for 2 hours before measurement. The result is the average of 8 samples. Production examples.

[0221] The components were mixed according to the percentages by weight specified in the tables. Mixing was carried out in a PC Laborsystem GmbH laboratory for 30 minutes under vacuum at room temperature. The mixtures were then filled into cartridges and stored in a freezer at -20 °C.

[0222] The following list contains all compounds used in the production of the curable compounds and their abbreviations. Unless otherwise stated, the tables give all component contents in percent by weight, based on the total weight of the compound.

[0223] Component (A):

[0224] A-1 : Epikote Resin 169 (mixture of bisphenol A and bisphenol F glycidyl ethers, equivalent weight: 169 g / mol, Westlake, USA)

[0225] A-2: Adeka Glycirole ED 509S (p-tert-Butylphenyl glycidyl ether, equivalent weight: 208 g / mol, Adeka company, Japan)

[0226] A-3: Shofree BATG (Bisphenol-A based tetraepoxide,

[0227] Equivalent weight: 124 g / mol, Resonac company, Japan)

[0228] Component (B):

[0229] B-1: TMPI (Tris(3-mercaptopropyl)isocyanurate)

[0230] B-2: Multhiol Y-3 (pentaerythritol tripropanethiol, Kowa company, Japan)

[0231] B-3: DCPD thiol (dicyclopentadienedithiol)

[0232] B-4: DMDO (1,8-Dimercapto-3,6-Dioxaoctane, Arkema, France)

[0233] Component (C):

[0234] C-1: Fujicure FXR-1081 (epoxy-amine adduct; Sanho Chemical Co. Ltd)

[0235] C-2: Ancamine 2442 (Modified cycloaliphatic / aliphatic amine, Evonik, Germany) Component (D):

[0236] D1-1: Sartomer SR833S (tricyclodecanedimethanol diacrylate,

[0237] Homopolymerization temperature: 185 °C, equivalent weight: 152.1 g / mol, Arkema company, France)

[0238] D1-2: Kayarad R-604 (2-[5-[(Acryloyloxy)methyl]-5-ethyl-1 ,3-dioxan-2-yl]-2- methylpropyl acrylate, homopolymerization temperature: 182 °C, equivalent weight: 163.2 g / mol, Nagase, Japan)

[0239] D1-3: Photomer 4356 (Tris[2-(acryloyloxy)ethyl]isocyanurate,

[0240] Homopolymerization temperature: 270 °C, equivalent weight: 141 g / mol, IGM Resins, Netherlands)

[0241] D1-4: SBPF-022 (9,9-Bis[4-(2-acryloyloxyethyloxy)phenyl]fluorene,

[0242] Homopolymerization temperature: 123 °C, equivalent weight: 273.3 g / mol, Shin-A T&C

[0243] D1-5: Sartomer SR349 (ethoxylated bisphenol A diacrylate,

[0244] Homopolymerization temperature: 65 °C, equivalent weight: 234.0 g / mol, Arkema company, France)

[0245] D2-1: Sartomer SR420 (3,3,5-trimethylcyclohexyl acrylate,

[0246] Homopolymerization temperature: 25 °C, equivalent weight: 195.0 g / mol, Arkema company, France)

[0247] Component (E):

[0248] E-1 : Omnirad TPO-L (2,4,6-Trimethylbenzoylphenylphosphinic acid ethyl ester, IGM Resins, Netherlands)

[0249] Component (F):

[0250] F-1: Pyrogallol (1,2,3-trihydroxybenzene, Sigma Aldrich)

[0251] F-2: Tributyl borate (company Sigma Aldrich)

[0252] F-3: para-toluenesulfonyl isocyanate (company Sigma Aldrich)

[0253] F-4: Tannic acid (Merck, Germany)

[0254] F-5: Tributyl borate (Merck, Germany) Component (G):

[0255] G-1: Cab-O-Sil TS-720 (Cabot Corporation, USA)

[0256] G-2: Fused Silica FB-3SDC (company Denka)

[0257] G-3: Efka PX 4733 (BASF SE) G-4: Glycerin (Merck, Germany)

[0258] Table 1: Composition and properties of the masses according to the examples.

[0259]

[0260] Table 2: Further composition and properties of the masses according to the examples.

[0261]

[0262] Table 3: Composition and properties of the masses according to the comparative examples.

[0263] nm: not measurable, mass hardened prematurely

[0264] The compositions according to the invention of Examples E1 to E15 comprise the essential components of the invention. These are the epoxy-containing compound (A), the thiol (B) comprising tris(3-mercaptopropyl)isocyanurate, the nitrogen-containing compound as an accelerator (C), the radically curable component (D) comprising at least a difunctional (meth)acrylate (D1), the radical photoinitiator (E), and the stabilizer (F). The compositions according to the invention have a long working time, cure at a temperature of 80 °C within 30 minutes, and meet all mechanical requirements.

[0265] Examples E1 and E3, as well as examples E11 and E12, show different ratios of the epoxy groups of component (A) to the radically curable groups of component (D), which, within the range according to the invention, lie between 0.015 and 0.250. The curable masses have a long working time and achieve high light-fix strengths with good compressive shear strengths.

[0266] Examples E2, E10, E13, and E18 have different stabilizer (F) compositions. These compounds also possess the desired property profile, although the use of stabilizers (F-3) to (F-5) instead of stabilizers (F-1) or (F-2) results in sometimes higher light-fixing strengths with longer curing times in heat curing. By adjusting the stabilizer (F), the property profile can thus be tailored to the desired application.

[0267] Examples E4 to E7 show formulations with alternative (meth)acrylates (D1). In example E5, an alternative accelerator (C) is also used. These mixtures also exhibit the desired behavior.

[0268] In example E8, a monofunctional (meth)acrylate is added as an ethylene-unsaturated compound (D2). The mixture exhibits increased light fixation resistance.

[0269] Examples E9 and E10 use the alternative accelerator (C-2). These compounds also exhibit the desired property profile. Example E13 shows a silica-filled system with additional additives (G). Despite the reduced (meth)acrylate (D1) content, high light fixation strengths and the desired hot-curing behavior are achieved.

[0270] Example E14 contains a monofunctional epoxy compound (A). Example E15 contains another thiol (B). These compounds also exhibit the desired behavior.

[0271] In comparative examples CE1 and CE5, the ratio of the epoxy groups of component (A) to the radically curable groups of component (D) is above the range of 0.015 to 0.250 according to the invention. The light fixation strength of the masses is insufficient.

[0272] In comparative examples CE2 and CE6, little or no component (A) was added, respectively. The ratio of the epoxy groups of component (A) to the radically curable groups of component (D) is below the range of 0.015 to 0.250 according to the invention. The masses cannot be cured at moderate temperatures.

[0273] Comparison examples CE3 and CE4 contain a thiol (B) that does not include tris(3-mercaptopropyl)isocyanurate. Comparison example CE3 does not achieve the required processing times and cures prematurely. CE4, on the other hand, was only partially cured after 30 minutes at 80 °C. Neither comparison example achieves the required light-fixing strength.

Claims

Patent claims 1. A mass that can be fixed by actinic radiation and hardened by heat, comprising the following components: (A) an epoxy-containing compound; (B) a thiol; (C) a nitrogen-containing compound as an accelerator; (D) a radically curable component comprising a (meth)acrylate (D1) wherein the (meth)acrylate (D1) is at least difunctional; (E) a radical photoinitiator; and (F) a stabilizer; characterized in that the thiol (B) comprises tris(3-mercaptopropyl)isocyanurate, the ratio of the epoxide groups of component (A) to the radically curable groups of component (D) is in the range of 0.015 to 0.250, and the (meth)acrylate (D1) has an equivalent weight of at least 100.0 g / mol.

2. Mass according to claim 1, wherein the epoxy-containing compound (A) has an equivalent weight of at most 300 g / mol.

3. Mass according to claim 1 or 2, wherein the epoxide-containing compound (A) comprises an aromatic epoxide.

4. Composition according to any of the preceding claims, wherein the ratio of the epoxy groups of component (A) to the radically curable groups of component (D) is in the range of 0.020 to 0.225 5. Mass according to any one of the preceding claims, wherein the thiol (B) comprises at least 70 wt.% tris(3-mercaptopropyl)isocyanurate, based on the total weight of the thiol (B) 6. Mass according to claim 5, wherein the thiol (B) consists of Tris(3-mercaptopropyl)isocyanurate.

7. Composition according to any of the preceding claims, wherein the (meth)acrylate (D1) has a homopolymerization glass transition temperature of 60 °C or higher.

8. Mass according to any of the preceding claims, wherein the radically curable component further comprises another ethylene unsaturated compound (D2) that is different from the (meth)acrylate (D1).

9. Mass according to any of the preceding claims, wherein the mass comprises the following components, each based on the total weight of components (A) to (F): (A) 0.5 to 15 wt.% of the epoxy-containing compound; (B) 15 to 70% by weight of the thiol; (C) 0.5 to 30 wt.% of the nitrogen-containing compound as an accelerator; (D) 20 to 80 wt.% of the radically curable component; (E) 0.01 to 5 wt% of the radical photoinitiator; and (F) 0.01 to 2 wt% of the stabilizer.

10. Mass according to claim 9, wherein the mass further contains up to 80 wt.% of additives as component (G), based on the total weight of the mass.

11. Mass according to claim 9 or 10, wherein the mass contains 0.5 to 12.0 wt.% of the epoxy compound (A), based on the total weight of components (A) to (F).

12. Mass according to any one of claims 9 to 11, wherein the mass contains 40 to 80 wt.% of the radically curable component (D), based on the total weight of components (A) to (F).

13. Use of the mass according to any of the preceding claims for bonding, potting, sealing and / or coating substrates.

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