EP4073139A1

EP4073139A1 - Light-fixation and moisture-cured masses based on epoxy resins and thiols

Info

Publication number: EP4073139A1
Application number: EP20820354.7A
Authority: EP
Inventors: Robert Deisling; Sabrina Rödiger; Markus Ehret; Andreas ZILLESSEN
Original assignee: Delo Industrieklebstoffe GmbH and Co Kgaa
Current assignee: Delo Industrieklebstoffe GmbH and Co Kgaa
Priority date: 2019-12-10
Filing date: 2020-12-02
Publication date: 2022-10-19
Also published as: WO2021115881A1; DE102019133694A1

Abstract

The invention relates to a single-component mass, which is liquid at ambient temperature and which can be fixed via irradiation with actinic radiation and can be cured via the influence of moisture. The mass comprises at least the following components: (A) an at least difunctional epoxy-containing compound; (B) an at least difunctional thiol; (C) a radiation-curable compound; (D) a photoinitiator; and (E) a moisture latent organic accelerator, which produces a basic compound with the influence of moisture. The mass can be used as an adhesive or sealant for adhesion, moulding, sealing or coating substrates, in particular optical and/or electronic components.

Description

Light-fixable and moisture-curing compounds based on epoxy resins and thiols

FIELD OF THE INVENTION

The present invention relates to a one-component material based on epoxy resins and thiols which is liquid at room temperature and which can be fixed by radiation and cured by the action of moisture.

The invention also relates to a method for joining, coating or potting substrates using the one-component compound.

TECHNICAL BACKGROUND

Epoxy compositions with thiol-based hardeners are disclosed, for example, in US Pat. No. 6,153,719 A and are distinguished by high reactivity and a short processing time at room temperature. For this reason, the compositions described are preferably provided as two-component systems in which the epoxy component is packaged and stored separately from the reactive hardener component.

In addition, one-component compositions based on epoxy compounds with hardeners based on thiols are known which have a limited storage stability and a short processing time at room temperature. It is known from US Pat. No. 5,430,112 that the stability of thiol-containing epoxy compositions at room temperature can be improved by adding a latent accelerator for epoxy curing which is obtained by reacting a primary or secondary amine with an isocyanate-containing compound to form a urea derivative. In addition, the use of solid amine compounds, which are sparingly soluble in the epoxy matrix at room temperature, as accelerators is described. The known epoxy compounds can only be activated thermally. US Pat. No. 6,232,426 B1 and US Pat. No. 7,479,534 B2 disclose thiol-containing epoxy compositions which contain a sparingly soluble nitrogen compound as a latent accelerator and additionally a Lewis acidic compound from the group of titanates and / or borates as a stabilizer to improve storage stability.

Another proposal for improving the stability of thiol-containing epoxy compositions is described in US Pat. No. 6,653,371 B1. In addition to an epoxy resin, a polythiol and a latent accelerator based on a nitrogen compound, the formulations also contain a solid organic acid. The organic acid is present in solid form dispersed in the epoxy matrix below the typical curing temperature of the composition and has a pKa of 12 or less.

The low stability of one-component epoxy compositions with thiol-based hardeners, which has been described many times in the prior art, simultaneously results in the advantage of a low hardening temperature. US 2017/0073459 A1 discloses the use of thiol-containing epoxy compounds that harden at 80 ° C. and are therefore intended to be suitable for use in the manufacture of temperature-sensitive components such as camera modules. In return, these compounds only have a very short processing time at room temperature.

Epoxy compositions suitable for electronic and optical applications should not only have a low curing temperature. Rather, the hardened masses should also have a high level of stability with respect to the effects of temperature and moisture. WO 2015/060439 A1 describes the use of a special ester-free thiol as a hardener for an epoxy resin in order to increase the moisture resistance of the hardened mass. An epoxy resin composition with an ester-free thiol based on a glycoluril structure is known from WO 2016/143815 A1.

All of the thiol-containing epoxy compounds described so far are purely heat-curing compounds.

The thermal energy required for curing and the associated costs are disadvantageous for ecological and economic reasons. In addition, the component can be damaged by the thermal load. US 2007/0096056 A1 discloses a one-component material which, in addition to an epoxy resin, a latent curing accelerator and an at least difunctional thiol, additionally comprises a radiation-curable compound based on a (meth) acrylate and a photoinitiator. Through the combination of two hardening mechanisms, the masses should harden safely even in shadow areas. However, the proportion of the difunctional thiol is limited to a maximum of 5% by weight in order to achieve a sufficient processing time at room temperature. Higher proportions of the thiol are undesirable because they have a negative impact on the stability of the compositions. However, the limitation of the thiol content restricts the freedom of formulation. Moisture-induced hardening of the masses is not described.

US Pat. No. 5,837,785 A1 describes a moisture-curable epoxy composition with high storage stability. The hardener used in the mass is selected from the group of nitrogen-heterocyclic reaction products of ketones with hydroxyamines and epoxides. The hardening of the epoxy compound takes place through the release of amines after exposure to moisture. The use of thiols and an option for light fixation are not described.

No. 6,803,445 A1 describes moisture-curable polyurethane and / or epoxy compositions. The moisture-latent hardener is selected from the group of oxazolidines, ketimines, enamines and silyl mercaptans. Upon contact with moisture, these release primary or secondary amino or thiol groups. A dual-curing formulation or the use of hardeners with free thiol groups is not described.

The use of oxazolidines, in particular polyoxazolidines, as latent hardeners for polyisocyanates, polyepoxides or polyacrylates has been known for a long time and is described, inter alia, in US Pat. No. 5,219,979 A1, US Pat. No. 3,743,626 A1 or EP 0228 935 A1.

The thiol-containing epoxy compositions described in the prior art cannot be cured with moisture induction. Furthermore, none of the known formulations combines such a moisture-induced curing with a light fixation option. SUMMARY OF THE INVENTION

The invention is based on the object of avoiding the disadvantages of the compositions known from the prior art and of providing one-component, storage-stable compositions which can be fixed by irradiation and hardened by the action of moisture.

Furthermore, the masses should have a high strength after moisture curing and should be completely curable within 14 days, preferably within 7 days.

These objects are achieved according to the invention by a one-component compound according to claim 1.

Advantageous embodiments of the composition according to the invention are specified in the subclaims, which can optionally be combined with one another.

The invention also relates to a method for joining, coating or potting substrates using the composition according to the invention. By irradiation, the mass applied to a substrate can be converted into a dimensionally stable state and optionally processed in subsequent process steps at a separate time. The irradiated mass can then be hardened by the ingress of moisture.

The invention also relates to the use of the composition according to the invention as an adhesive or sealant for gluing, potting, sealing or coating substrates, in particular optical and / or electronic components.

The one-component composition according to the invention is liquid at room temperature and can be fixed by radiation and hardened by moisture. The composition comprises at least the following components: (A) an at least difunctional epoxy-containing compound; (B) an at least difunctional thiol; (C) a radiation curable compound; (D) a photoinitiator and (E) a moisture-latent organic accelerator which generates a basic compound when exposed to moisture. The one-component composition according to the invention has sufficient processability at room temperature of preferably at least 24 hours, particularly preferably at least 72 hours, and can be converted into a dimensionally stable state by exposure to actinic radiation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention is described in detail and by way of example below on the basis of preferred embodiments, which, however, should not be understood in a restrictive sense.

"One-component" or "one-component compound" means in the context of the invention that the named components of the compound are present together in a common formulation, that is, are not stored separately from one another.

“Liquid” in the sense of the invention 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.

The masses are considered to be “storage-stable” and / or “processable” if the viscosity of the respective mass increases by less than 100% during storage at room temperature over a period of at least 24 hours, preferably at least 72 hours.

Insofar as the indefinite article “a” or “an” is used, the plural form “one or more” is also included, unless this is expressly excluded.

“At least difunctional” means that two or more units of the functional group mentioned are contained per molecule.

All the weight fractions listed below relate in each case to the total weight of the reactive components (A) to (E). Component (AI: at least difunctional epoxy compound

The at least difunctional epoxy compound (A) is not restricted in its chemical structure and includes aromatic or aliphatic compounds with at least two epoxy groups in the molecule, such as, for example, aliphatic and cycloaliphatic epoxides, glycidyl ethers, glycidylamines and mixtures thereof.

Di- or higher-functional cycloaliphatic epoxy compounds are known in the prior art and include compounds which carry both a cycloaliphatic group and at least two oxirane rings. Exemplary representatives are 3-cyclohexenylmethyl-3-cyclohexylcarboxylate diepoxide, 3,4-epoxycyclohexylalkyl-3 ', 4'-epoxy-cyclohexane carboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3', 4'-epoxy-6-methyl-cyclohexane carboxylate , Vinylcyclohexene dioxide, bis (3,4-

Epoxycyclohexylmethyl) adipate, dicyclopentadiene dioxide, 1,2-epoxy-6- (2,3-epoxypropoxy) hexahydro-4,7-methanindane.

Aromatic epoxy compounds can also be used in the compositions of the invention. Examples of aromatic epoxy compounds are bisphenol A epoxy resins, bisphenol F epoxy resins, phenol novolak epoxy resins, cresol novolak epoxy resins, biphenyl epoxy resins, 4,4‘-biphenyl epoxy resins, divinylbenzene dioxide, 2-glycidylphenyl glycidyl ether,

Naphthalenediol diglycidyl ether, glycidyl ether of tris (hydroxyphenyl) methane, glycidyl ether of tris (hydroxyphenyl) ethane. Furthermore, all fully or partially hydrogenated analogs of aromatic epoxy compounds can also be used. Low-halogen or halogen-free bisphenol A and bisphenol F epoxy resins are preferred.

Isocyanurates substituted with epoxy-containing groups and other heterocyclic compounds can also be used as component (A) in the compositions according to the invention. Triglycidyl isocyanurate and monoallyl diglycidyl isocyanurate may be mentioned by way of example.

In addition, it is also possible to use polyfunctional epoxy resins of all the resin groups mentioned, tough elasticized epoxy resins and mixtures of different epoxy compounds in the compositions according to the invention. A combination of several di- or higher-functional epoxy compounds is also within the meaning of the invention.

Suitable epoxy-containing compounds (A) are available under the trade names CELLOXIDE ™ 2021 P, CELLOXIDE ™ 8000 from Daicel Corporation, Japan, or EPIKOTE ™ RESIN 828 LVEL, EPIKOTE ™ RESIN 166, EPIKOTE ™ RESIN 169 from Momentive Specialty Chemicals BV, The Netherlands, or Epilox ™ resins of the product series A, T and AF from Leuna Harze, Germany, or EPICLON ™ 840, 840-S, 850, 850-S, EXA850CRP, 850-LC from DIC KK, Japan, are commercially available . Component (A) is present in the composition according to the invention in a proportion of 5 to 70% by weight, based on the total weight of components (A) to (E).

Component (Bl: At least difunctional thiol

The at least difunctional thiol (B) serves as a hardener in the composition according to the invention and comprises compounds with at least two thiol groups (-SH) in the molecule.

The chemical structure of component (B) is not restricted further and preferably comprises aromatic and aliphatic thiols and combinations thereof. The at least difunctional thiol is preferably selected from the group consisting of ester-based thiols, polyethers with reactive thiol groups, polythioethers, polythioether acetals, polythioether thioacetals, polysulfides, thiol-terminated urethanes, thiol derivatives of isocyanurates and glycoluril and combinations thereof. Examples of commercially available ester-based thiols based on 2-mercaptoacetic acid include trimethylolpropane-trimercaptoacetate,

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

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

The use of ester-free thiols is particularly preferred with regard to increased resistance of the cured masses to temperature and moisture. Examples of ester-free thiols can be found in JP 2012 153 794 A, which is incorporated into the description by reference.

A use of tris (3-mercaptopropyl) isocyanurate (TMPI) as a trifunctional ester-free thiol is particularly preferred in the composition according to the invention. It has been shown that this thiol both ensures good hydrolytic stability and improves adhesion to various substrates. According to a particularly preferred embodiment, the at least difunctional thiol of component (B) therefore comprises tris (3-mercaptopropyl) isocyanurate, alone or in a mixture with other at least difunctional thiols.

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 compositions according to the invention, alone or in a mixture with other at least difunctional thiols.

Thiols of higher functionality, which are obtainable, for example, by oxidative dimerization processes of at least difunctional thiols, can also be used in component (B).

The above list is to be seen as exemplary and not conclusive. The at least difunctional thiol is preferably present in the composition according to the invention in a proportion of 10 to 80, preferably 15 to 70% by weight, based on the total weight of components (A) to (E).

Component (CI: Radiation-hardening compound

The radiation-curing compounds used in the compositions according to the invention are those with groups which can be polymerized by free radicals. The free-radically polymerizable groups are alkene or alkyne groups, preferably terminal alkene groups and particularly preferably (meth) acrylate groups. Their chemical structure is not restricted any further. For example, both aliphatic and aromatic (meth) acrylates can be used.

The radiation-curing compound is preferably at least difunctional. For example, the following radiation-curing compounds are suitable: isobornyl acrylate, stearyl acrylate, tetrahydrofurfuryl acrylate, cyclohexyl acrylate,

3.3.5-trimethylcyclohexanol acrylate, behenyl acrylate, 2-methoxyethyl acrylate and other mono- or polyalkoxylated alkyl acrylates, isobutyl acrylate, isooctyl acrylate, lauryl acrylate, tridecyl acrylate, isostearyl acrylate, 2- (o-phenylphenoxy) ethyl acrylate, n-butyl acrylate, 4- butylmorpholine, niacyl acrylate, n-butylmorpholine, 4- butylmorpholine , 1, 6-hexanediol diacrylate, 1, 10-decanediol diacrylate,

Tricyclodecane dimethanol diacrylate, dipropylene glycol diacrylate,

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

The analogous methacrylates are also within the meaning of the invention.

Furthermore, compounds with allyl groups, such as, for example, are also suitable

1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, commercially available as TAICROS ^®. Also unhydrogenated polybutadienes with free double bonds, such as the Poly BD ^® grades can be used as a radiation curing compound (C) become. The use of vinyl ethers is also possible, as is the use of unsaturated polyester resins.

Urethane acrylates based on polyesters, polyethers, polycarbonate diols and / or fully or partially hydrogenated, (meth) acrylate-functionalized polybutadiene diols can also be used as component (C) as the higher molecular weight radiation-curing compound.

Examples of commercially available radiation curing compounds are CN9001, CN9002, CN925, CN981, CN9165A and CN9163 available from Sartomer, as well as SHIKOH UV-3700B, UV-3200B, UV-3300B, UV-3310B, UV-7600B, UV-7630B, UV -7510B available from Nippon Gohsei.

In addition, hybrid compounds can also be used as component (C). In addition to at least one radical radiation-curable group, these also contain an addition-crosslinking group. In particular, epoxy (meth) acrylate hybrid compounds are within the meaning of the invention.

A combination of several radiation-curing compounds is also within the meaning of the invention.

The radiation-curing compound can comprise a mixture of a monofunctional radiation-curing compound and an at least difunctional radiation-curing compound. In this case, the monofunctional radiation-curing compound can be present in a proportion of 0 to 10% by weight, based on the total weight of components (A) to (E).

The radiation-curing compound is preferably present in the one-component composition according to the invention in a proportion of 1 to 70% by weight, particularly preferably in a proportion of 10 to 50% by weight.

In order to achieve high resistance to light fixation with short exposure times, the compositions according to the invention preferably contain at least 15% by weight of an at least difunctional, radiation-curing compound as component (C), based on the total weight of components (A) to (E). The at least difunctional radiation-curing compound is preferably present in the composition according to the invention in a proportion of 5 to 50, preferably 15 to 40% by weight. Component (Dl: photoinitiator

In addition to the radiation-curing compound (C), the compositions also contain at least one photoinitiator (D) for free-radical polymerization. The usual, commercially available compounds can be used as photoinitiators, such as a-hydroxyketone, benzophenone, a, a'-diethoxyacetophenone, 4,4-diethylaminobenzophenone, 2,2-dimethoxy-2-phenyl-acetophenone, 4-isopropylphenyl- 2-hydroxy-2-propyl ketone, 1-

Hydroxycyclohexyl phenyl ketone, isoamyl p-dimethylaminobenzoate, methyl 4-dimethylaminobenzoate, methyl o-benzoyl benzoate, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2- Isopropylthioxanthone, dibenzosuberone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bisacylphosphine oxides, it being possible for the photoinitiators mentioned to be used alone or in combination of two or more of the compounds mentioned.

The IRGACURE ™ types from BASF SE can be used as UV photoinitiators, for example the types IRGACURE 184, IRGACURE 500, IRGACURE 1179, IRGACURE 2959, IRGACURE 745, IRGACURE 651, IRGACURE 369, IRGACURE 907, IRGACURE 1300, IRGACURE 819 , IRGACURE 819DW, IRGACURE 2022, IRGACURE 2100, IRGACURE 784, IRGACURE 250, IRGACURE TPO, IRGACURE TPO-L. The DAROCUR ™ types from BASF SE can also be used, for example the types DAROCUR MBF, DAROCUR 1173, DAROCUR TPO and DAROCUR 4265.

The photoinitiator used as component (D) in the compositions according to the invention can preferably be activated by actinic radiation with a wavelength of 200 to 600 nm, particularly preferably from 320 to 480 nm. If necessary, the photoinitiator can be combined with a suitable sensitizer.

The photoinitiator (D) is preferably present in the compositions according to the invention in a proportion of 0.01 to 5% by weight, based on the total weight of components (A) to (E). Component (El: moisture-latent accelerator

The compositions according to the invention contain a moisture-latent organic accelerator as an essential feature. This is not structurally restricted and is characterized in that the accelerator generates at least one basic compound under the action of moisture by hydrolysis. These are preferably nitrogen-containing compounds.

“Basic” here means a compound with a pH value greater than 7, preferably a pH value of 8 or more.

The moisture-latent accelerator (E) preferably has a molar mass of greater than 200 g / mol, particularly preferably greater than 300 g / mol.

Compounds selected from the group of the oxazolidines, ketimines, aldimines and enamines are particularly preferably used as moisture-latent accelerators.

Oxazolidine compounds according to formula 1 are very particularly preferably used as moisture-latent accelerators.

formula 1

In general formula 1, R ¹ and R ^{2 are} independently a monovalent organic radical, preferably an aliphatic, cycloaliphatic or aromatic radical with 1 to 500 carbon atoms, which can optionally be interrupted by heteroatoms and / or carry heteroatom-containing substituents, for example substituents with one or more epoxy groups, (meth) acrylate groups and / or further oxazolidine groups. The oxazolidine functionality of the accelerator is preferably difunctional or higher, that is to say the accelerator is an oxazolidine compound which has two or more oxazolidine groups. The preparation of oxazolidines can be found in US 4002601 A, US 4 002 637 or DE 3 019 356 A1, for example.

Without wishing to be bound by a scientific theory, the moisture-latent accelerator acts in the masses in such a way that hydrolysis takes place when moisture penetrates, during which a nitrogen-containing compound and, optionally, other cleavage products are released. For example, the oxazolidine of formula 1 breaks down under the action of moisture into a carbonyl compound and an amino alcohol. The released amino alcohol can subsequently deprotonate the at least difunctional thiol (B) and thus cause a hardening reaction in the mass.

The moisture-latent accelerator (E) is preferably present in the compositions according to the invention in a proportion of 1 to 25% by weight, based on the total weight of components (A) to (E), and particularly preferably in a proportion of 4 to 20% .

Component (Fl: additives

In addition to components (A) to (E), the compositions according to the invention can contain further additives (F). Preferred additives (F) are toughness modifiers such as core-shell particles or block copolymers, dyes, pigments, fluorescent agents, thixotropic agents, thickeners, stabilizers, antioxidants, plasticizers, tackifiers, fillers, flame retardants, drying agents, corrosion inhibitors, inert and reactive diluents, including of monofunctional epoxies, leveling and wetting additives, adhesion promoters and other accelerators, as well as combinations thereof.

In particular, a heat-latent accelerator can be used as a further accelerator (F2), which is preferably in solid form dispersed in the composition at room temperature and melts when heated. Furthermore, heat-latent, liquid accelerators can also be used, in particular liquid accelerators with blocked amine groups, which are converted into the free amine compound when heated.

The further accelerator is preferably a nitrogen-containing compound, particularly preferably one from the group of amines, ureas, imidazoles, Triazine derivatives, polyamidoamines and / or guanidines selected compound. The melting point of the nitrogen-containing compound is preferably equal to or greater than 60.degree.

Furthermore, adducts and / or reaction products of epoxides or isocyanates with the nitrogen compounds mentioned can be used as accelerators, in particular reaction products with amines, as already described in US Pat. No. 5,430,112.

Examples of commercially available accelerators are 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.) And Curezol (available from Shikoku Chemicals Corporation). The accelerators can also be present in encapsulated form. As examples of commercially available products are Technicure ^® LC-80 and Technicure ^® LC-100 called the company ACCI Specialty Materials.

In addition to the use of the compounds mentioned, the use of photolatent bases as a further accelerator (F3) is also possible. Examples of possible substance classes are 4- (ortho-nitrophenyl) -dihydropyridine, quaternary organoboron compounds, alpha-amino-acetophenones or amines blocked with photolatent groups. These can release basic compounds through actinic radiation and thus also act as accelerators.

In addition to heat-latent and photo-latent accelerators, inorganic basic accelerators (F4) can also be used to accelerate the hardening process. These are preferably in solid form in the masses. In particular, basic metal oxides such as calcium oxide, magnesium oxide and strontium oxide can be used as inorganic accelerators.

Formulation of the compositions according to the invention:

A formulation of the one-component compositions according to the invention preferably comprises the following components, each based on the total weight of components (A) to (E): (A) 5-70% by weight of an at least difunctional epoxy-containing compound;

(B) 15-70% by weight of an at least difunctional thiol; preferably an ester-free thiol, alone or in admixture with other difunctional thiols;

(C) 10-50% by weight of an at least difunctional (meth) acrylate;

(D) 0.1-5% by weight of a photoinitiator;

(E) 4-20% by weight of a moisture-latent accelerator from the group of oxazolidines, ketimines, aldimines and / or enamines

(F) 0 to 60% by weight of one or more additives.

According to a preferred embodiment, the formulation consists of the components (A) to (E) mentioned and optionally (F).

Processing time of the inventive masses

The compositions according to the invention can be stored at room temperature and, as long as there is no ingress of moisture, can be processed without restriction over a period of up to 3 days, particularly preferably up to 7 days and very particularly preferably up to 14 days.

Light fixation of the masses according to the invention

The compositions according to the invention can be fixed by exposure to actinic radiation. In the context of the invention, “fixation” denotes the build-up of a strength from which the mass can no longer flow at room temperature, or a degree of strength from which joined parts can be handled in subsequent processes without destroying the adhesive bond comes.

Due to the possibility of light fixation, the compositions according to the invention are suitable, despite slow moisture curing, for fast industrial processes with short cycle times, in which at the same time the lowest possible thermal load on the components involved is required. The invention therefore also relates to the use of the compositions according to the invention as an adhesive or sealant for gluing, potting, sealing or coating substrates. Optical and / or electronic components are preferably used as substrates.

The compositions applied to the components and fixed by exposure to actinic radiation are preferably cured by the action of moisture at room temperature. The hardening reaction can be accelerated either by heating or by increased humidity.

The advantage of the compositions according to the invention, however, is that the bonded, encapsulated or coated substrate does not necessarily have to be heated to a temperature of over 40 ° C., preferably not over 30 ° C., after light fixation for complete curing.

Joining or coating processes using the compositions according to the invention

The compositions according to the invention offer the further advantage that, in joining processes, the components can be fixed in their position relative to one another by exposure to actinic radiation.

A corresponding method for gluing, casting or coating substrates using the compositions according to the invention preferably comprises the following steps: a) metering the composition onto a first substrate; b) fixing the mass by exposure to actinic radiation; and c) optionally supplying a second substrate before or after step b), with the formation of a substrate composite, the second substrate being brought into contact with the mass; d) Allowing moisture to act on the fixed mass until the final strength is built up

At a relative humidity of 50% RH, the masses reach their final strength within 14 days, preferably within 7 days. In addition to the moisture available in the environment and on the substrate, the length of time until complete curing is determined by the layer thickness to be cured and the access options for moisture, which is determined, for example, by the geometry of the components to be joined and their moisture permeability.

With the aid of the method according to the invention, a high degree of positional accuracy of the joined components can be achieved until final hardening. Conventional fixing aids, which in practice cannot be used with miniaturized components or which entail unreasonable additional expenditure, can thus be dispensed with.

The masses which have been light-fixed by irradiation have sufficient strength if a shear strength of at least 4 N die-shear strength is achieved immediately after exposure, for example after exposure to 200 mW / cm ² for 10 seconds. The shear strength of the light-fixed material is preferably at least 8 N. By using a higher exposure intensity, the same light-fixing strength can be achieved with a shorter exposure time.

The compositions according to the invention also have short light fixing times and can be fixed in layer thicknesses of 100 μm at radiation intensities of 200 mW / mm ² in a maximum of 15 s, preferably in a maximum of 10 s, particularly preferably in a maximum of 5 s with the required shear strength. With the compositions according to the invention, light fixation times of down to 0.5 s can be achieved.

The composition according to the invention is preferably brought into contact with a second substrate before the light fixation and joined to form the substrate composite. The compositions according to the invention are, however, also distinguished by the fact that the composition applied to a substrate can be converted into a so-called B-stage state by irradiation. In this state, the mass has sufficient shape and contour stability and can therefore be processed in downstream processes without flowing. In particular, the mass can be processed in a pressure-sensitively adhesive B-stage state by joining to the second substrate to form a substrate composite. Measurement methods and definitions used

Irradiation

For the irradiation, the compositions according to the invention were irradiated with LED lamps of the DELOLUX series from DELO Industrie Klebstoffe GmbH & Co. KGaA with a wavelength of 400 nm at an intensity of 200 ± 20 mW / cm ² .

Moisture hardening

“Crosslinking” or “curing” are defined as a polymerization or addition reaction beyond the gel point. The gel point is the point at which the storage modulus G ‘becomes equal to the loss modulus G ″. In order to determine the hardening time, three drops of the mass were applied to each slide. The slide was then stored at 23 ° C and 50% r.h. stored. A plastic spatula was used to check at periodic intervals when the drop was no longer liquid.

Room temperature

Room temperature is defined as 23 ± 2 ° C.

Change in viscosity at room temperature

The viscosity was measured with a Physica MCR302 rheometer from Anton Paar with a standardized PP20 measuring cone at 23 ° C. with a 200 μm gap and determined at a shear rate of 10 / second. To assess the storage stability at room temperature, the viscosity measurement was repeated periodically.

Changes in viscosity of less than 25% to the starting value were assessed as very good (++), of less than 50% as good (+), of less than 100% as sufficient (o), from 100 to 200% as inadequate and of more than 200% as insufficient.

Storage stability under exclusion of moisture

In parallel to the determination of the curing time for moisture curing, a cartridge of each of the materials from Table 1 was vacuum-welded and stored under analogous conditions. After the open drop has hardened, the Stored cartridge opened and squeezed out. If the mass was still liquid, it is still processable for at least the elapsed period at room temperature.

The Shear Strength After Light Fixation The light fixation strength was determined using the Dage Series 4000 bond tester, available from Nordson. For this purpose, a 4 x 4 x 4 mm glass cube was glued to a 20 x 20 x 5 mm FR4 test specimen (layer thickness 100 μm), and the gluing was carried out for 10.0 seconds with radiation at a wavelength of 400 nm and an intensity of 200 ± 20 mW / cm ² exposed. Subsequently, after 1 hour of storage in the dark at room temperature, the shear strength was determined with the aid of the bond tester.

Final strength after light fixation and moisture curing

The strength after light fixation and moisture curing was determined analogously by a DieShear test, with a waiting time of 14 days before the measurement due to storage at room temperature and a relative humidity of 50% r.h. was adhered to.

Compressive shear strength

In each case two test specimens (dimensions 20 mm * 20 mm * 5 mm) made of steel were glued with a 5 mm overlap using the respective mass. For this purpose, a bead from the mass was applied to the first test specimen and spread thinly. A second test specimen was then joined. The adhesive layer thickness of 0.1 mm and the overlap were set using spacer wires and an adhesive device. The joined samples were dark at 23 ° C and 50% r.h. before the test. stored for 14 days. Strengths of less than six MPa are insufficient (-), strengths of six to eight MPa are unsatisfactory (-), strengths of 8 to 10 MPa are sufficient (o), strengths of 10 MPa to 12 MPa are good (+) and strengths above 12 MPa are very good (++)

Production of the curable compositions The production of the hardenable compositions used in the following examples is preferably carried out at a relative humidity of less than 20% less than 10%. For example, the production can take place in a glove box in which there is a dry (inert) atmosphere.

First, the liquid components are mixed and then the fillers and optionally other solids are incorporated using a laboratory stirrer, laboratory dissolver or a speed mixer (Hauschild) until a homogeneous mass is created. Compositions which contain photoinitiators and which are sensitive to visible light must accordingly be produced under light outside the excitation wavelength of the photoinitiators or sensitizers.

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

The following list shows all the compounds and their abbreviations used to produce the curable materials:

Component (A): At least difunctional epoxy-containing compound

A1: Epikote Resin 828 LVEL (bisphenol A glycidyl ether, available from Hexion)

Component (B): At least difunctional thiol

B1: tris (3-mercaptopropyl) isocyanurate

B2: Maternity leave MT PE1 (pentaerythritol tetrakis (3-mercaptobutylate), available from Showa Denko)

Component (C): Radiation-non-curable compound

C1: Photomer 4006 (trimethylolpropane triacrylate, available from IGM Resins)

C2: Sartomer SR350D (trimethylolpropane trimethacrylate, available from

Arkema company)

C3: Hybrid connection analogous to preparation example 1 from DE 102 018 121 067 Component (Dl: photoinitiator

D1: Irgacure TPO-L (ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate, available from IGM Resins)

D2: CGI 277 (1- (3,4-dimethoxyphenyl) -2- (dimethylamino) -2- (phenylmethyl) -butan-1-one, available from BASF)

Component (E): moisture-latent accelerator

E1: Incozol EH (urethane bridged bisoxazolidine, available from Incorez)

E2: Incozol LV: (carbonate-bridged bisoxazolidine, available from Incorez)

Component (F): Additives F1-1: Pyrogallol, available from Sigma Aldrich.

F1-2: Cab-o-Sil TS-720 (hydrophobic fumed silica, available from Cabot Corporation)

F4-1: Kezadol PCI (phlegmatized calcium oxide powder, available from Kettlitz)

Formulation of the compositions according to the invention

Properties of the formulations

The compositions according to the invention of Examples 1-5 all cure within 7 days due to moisture. Comparative example 1, which does not contain any moisture-latent accelerator (E), remains liquid even after 14 days in the presence of moisture. At the same time, the compositions according to the invention remain liquid for at least 7 days when the ingress of moisture is prevented. Furthermore, examples 1 to 5 show on the basis of the change in viscosity that these remain processable even over a period of up to 14 days at room temperature in the absence of moisture. The compositions according to the invention of Examples 1 to 5 can be fixed with light. These materials then build up high strengths even in unexposed areas after moisture curing.

Claims

Patent claims:

1. One-component mass which is liquid at room temperature and which can be fixed by exposure to actinic radiation and cured by exposure to moisture, the mass comprising at least the following components:

(A) an at least difunctional epoxy-containing compound;

(B) an at least difunctional thiol;

(C) a radiation curable compound;

(D) a photoinitiator; and

(E) a moisture-latent organic accelerator that generates a basic compound when exposed to moisture.

2. One-component composition according to claim 1, characterized in that the thiol is selected from the group consisting of ester-based thiols, polyethers with reactive thiol groups, polythioethers, polythioether acetals, polythioetherthioacetals, polysulfides, thiol-terminated urethanes, thiol derivatives of isocyanurates and glycoluril, and combinations thereof.

3. One-component composition according to claim 1 or 2, characterized in that the thiol comprises an ester-based thiol based on 2-mercaptoacetic acid, preferably trimethylolpropane-trimercaptoacetate, pentaerythritol-tetramercaptoacetate or glycol dimercaptoacetate, and / or an ester-based thiol from the group of trimethylolpropane-tris (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutylate), glycol di (3-mercaptopropionate) and tris [2- (3-mercaptopropionyloxy) ethyl] isocyanurate.

4. One-component composition according to one of the preceding claims, characterized in that the thiol comprises a thioether, preferably DMDO (1,8-Dimercapto-3,6-dioxaoctane), DMDS (Dimercaptodiethylsulfide) and / or DMPT (2,3-Di ( (2-mercaptoethyl) thio) -1-propane-thiol).

5. One-component composition according to one of the preceding claims, characterized in that the thiol comprises an ester-free thiol, preferably Tris (3-mercaptopropyl) isocyanurate, alone or in a mixture with other at least difunctional thiols.

6. One-component composition according to one of the preceding claims, characterized in that the at least difunctional thiol is present in a proportion of 10 to 80 percent by weight, based on the total weight of components (A) to (E), preferably in a proportion of 15 to 70 wt .-%.

7. One-component composition according to one of the preceding claims, characterized in that the moisture-latent accelerator is selected from the group of oxazolidines, ketimines, aldimines and enamines.

8. One-component composition according to one of the preceding claims, characterized in that the moisture-latent accelerator is an oxazolidine compound of the following general formula 1:

formula 1 wherein R ¹ and R ^{2 are} independently a monovalent organic radical, preferably an aliphatic, cycloaliphatic or aromatic radical with 1 to 500 carbon atoms, which can optionally be interrupted by heteroatoms and / or carry heteroatom-containing substituents, preferably substituents with one or several epoxy groups, (meth) acrylate groups and / or further oxazolidine groups.

9. One-component composition according to claim 7 or 8, characterized in that the accelerator is an oxazolidine compound having at least two oxazolidine groups.

10. One-component composition according to one of the preceding claims, characterized in that the moisture-latent accelerator is present in a proportion of 1 to 25% by weight, based on the total weight of components (A) to (E), and preferably in a proportion of 4 up to 20% by weight.

11. One-component mass according to one of the preceding claims, characterized in that the mass comprises the following components, each based on the total weight of components (A) to (E):

(A) 5 to 70% by weight of an at least difunctional epoxy-containing compound;

(B) 15 to 70% by weight of an at least difunctional thiol; preferably an ester-free thiol, alone or in admixture with other difunctional thiols;

(C) 10 to 50% by weight of an at least difunctional (meth) acrylate;

(D) 0.1 to 5% by weight of a photoinitiator;

(E) 4 to 20% by weight of a moisture-latent accelerator from the group of the oxazolidines, ketimines, aldimines and / or enamines; and

(F) 0 to 60% by weight of one or more additives.

12. One-component mass according to one of the preceding claims, characterized in that the mass contains at least one further accelerator as an additive, which is selected from the group of heat-latent or photolatent accelerators and inorganic basic compounds and combinations thereof.

13. One-component mass according to one of the preceding claims, characterized in that the mass comprises one or more of the following properties:

A storage stability with exclusion of moisture at room temperature of at least 3 days, particularly at least 7 days and very particularly preferably at least 14 days;

A curing time at 50% rel. Humidity and room temperature for a maximum of 14 days until the final strength is reached, preferably a maximum of 7 days.

14. Use of the one-component compound according to one of the preceding claims for joining, coating or casting substrates.

15. A method for joining, coating or casting substrates, which comprises the following steps: a) metering the mass onto a first substrate; b) fixing the mass by exposure to actinic radiation; c) optionally supplying a second substrate before or after step b) with the formation of a substrate composite, the second substrate being brought into contact with the mass; and d) allowing moisture to act on the fixed mass until the final strength is built up.