Curable materials based on cyclic thioether compounds, and uses thereof

Abstract

The invention relates to a curable material that is liquid at room temperature and contains at least one thioether compound (A), at least one initiator (B) and at least one catalyst (C), the at least one thioether compound (A) comprising an at least bifunctional cyclic thioether.

Description

[0001] DELO Industrie Klebstoffe GmbH & Co. KGaA Our reference: D 3242 WO WS / TH

[0002] Curable compositions based on cyclic thioether compounds and use thereof

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to curable compositions based on at least one thioether compound comprising an at least difunctional cyclic thioether, an initiator, and a catalyst. Furthermore, the invention relates to the use of these curable compositions for joining, casting, and / or coating substrates.

[0005] TECHNICAL BACKGROUND

[0006] Polyinsertions are polymerization reactions in which a monomer is inserted between a growing chain and an initiator. One example is the Ziegler-Natta process for the production of linear olefins. In this case, the monomer attaches to a free coordination site of a metal catalyst and then inserts into the metal-carbon bond, resulting in chain growth (also known as "coordinative polymerization"). If the end of the growing polymer chain is bound to the initiator, ring expansion polymerization occurs, as is known, for example, from cyclic metathesis catalysts. The initiator is not limited to metal complexes but also includes functional organic molecules such as lactones or esters. An overview can be found in the scientific publication by Chang and Waymouth in the journal "Polymer Chemistry 1(2017, Volume 55, pages 2892 to 2902, doi: 10.1002 / pola.28635).

[0007] Thiiranes are the sulfur-containing analogues of epoxides and, in contrast to these, are only suitable to a limited extent for cationic polymerization. Thiiranes, on the other hand, prefer polyaddition reactions, anionic polymerizations, or polyinsertion reactions. One way to polymerize thiiranes in a polyinsertion reaction is through initiators that have a (thio)carbonylthio group as a key functional unit. Since the initiator is incorporated into the polymer and thus consumed in this type of polymerization, it no longer functions as a catalyst by definition. The resulting polythioethers are characterized by high media resistance and flexibility at low temperatures and are suitable as sealants for aerospace applications. They are also suitable as high-index components in optical materials such as lenses and optical filters.

[0008] Thiiranes can be obtained, for example, by reacting epoxides with thioureas, thiocyanates, or 3-methyl-2-benzothiazolinethione by direct transfer of a sulfur atom. US Pat. No. 8,969,503 B2 describes a melt extrusion process for producing thiiranes from the corresponding epoxides using thiourea derivatives, thiocyanates, or phosphine sulfides as sulfur donors. Further examples can be found in JP 2019 / 008289 A, US Pat. No. 6,631,021 B2, JP 2001 / 163874 A, JP 2002 / 241499 A, and JP 2005 / 343910 A.

[0009] Methods for the preparation of cyclic polysulfides using thiirane (poly)ring insertion reactions are known in the prior art. Selected examples can be found in the scientific publications by A. Kameyama, M. Kiyota, and T. Nishikubo in "Tetrahedron Letters" (1994, Volume 35, Issue 26, pages 4571 to 4574) and A. Kameyama, Y. Murakami, and T. Nishikubo in "Macromolecules" (1996, Volume 29, Issue 20, pages 6676 to 6678).

[0010] JP 4 977 099 B2 describes a process for preparing cyclic polysulfides containing radically polymerizable groups, as well as polymers produced therefrom by polymerizing the radically polymerizable group. 2,4-Thiazolidinedione is used as the initiator, which is reacted with thiirane monomers in a (poly)ring insertion to form cyclic polysulfides and then functionalized with an allyl group by reaction with 3-chloromethylstyrene. Radical polymerization thus yields a polymer containing cyclic polysulfides. The disclosure proposes the use of the polymer as a topological gel. Use as a curable composition is not envisaged. JP 3 976 438 B2 discloses the reaction of difunctional, aromatic haloformyl compounds with aromatic dithiols and subsequent reaction of the products (aryl thiocarbonates) with thiiranes.At least one thiirane unit inserts into the newly formed sulfur-carbonyl bonds. The resulting polymers have a high sulfur content and a high refractive index. They are suitable for use as optical elements for, among other things, lenses, optical filters, coatings, or anti-reflective films. Use as a curable composition is also not described.

[0011] Other suitable cyclic initiators can be found, for example, in JP 2001 261 834 A, JP 2005 281 241 A, JP 2008 231 349 A, and the scientific publication by H. Kudo, S. Makino, A. Kameyama, and T. Nishikubo in "Macromolecules" (2005, Volume 38, Issue 14, pages 5964 to 5969, doi: 10.1021 / ma047642h). The thiiranes used preferably contain alkoxymethyl or phenoxymethyl groups; the use of cycloaliphatic, allyl-, and propargyl ether-functionalized thiiranes has also been described.

[0012] The scientific publication by Zhang et al. in "Nature Communications" (2020, Volume 11, pages 1 to 10, doi: 10.1038 / s41467-020-17474-0) discloses multicyclic polymers based on polyrhodanines. Higher-functionality initiators are obtained by condensing rhodanine with di- or trifunctional aldehydes. Furthermore, crosslinking of the initiators is possible by N-functionalization of the rhodanine component. Polyinsertion always occurs finally at the polyfunctional initiator backbone. Crosslinking of the polyether rings is severely limited by the proportion of initiator component per polyether ring. The construction of polymer structures containing highly crosslinked macrocyclic polythioether components is not possible in this way.

[0013] SUMMARY OF THE INVENTION

[0014] The invention is based on the object of providing a one-component, curable composition based on thioether compounds that is liquid at room temperature and suitable as an adhesive, potting, or coating material. This object is achieved according to the invention by a curable composition according to claim 1 and the use of this composition according to claim 12, as well as in a method according to claim 14.

[0015] Advantageous embodiments of the composition according to the invention are specified in the subclaims, which can optionally be combined with one another.

[0016] The compositions according to the invention comprise the following components: a) at least one thioether compound (A), wherein the at least one thioether compound (A) comprises an at least difunctional cyclic thioether, b) at least one initiator (B), and c) at least one catalyst (C).

[0017] The compositions according to the invention are liquid at room temperature and can be cured by heat.

[0018] DETAILED DESCRIPTION

[0019] The invention is described in detail below by way of example and with reference to preferred embodiments, which, however, are not intended to be limiting, and with reference to the drawings.

[0020] - Fig. 1 is a DSC curve of a curable composition according to the invention, and

[0021] - Fig. 2 an isothermal measurement of the curable mass from Fig. 1 , carried out at a temperature of 80 °C.

[0022] In the context of the invention, “liquid” means that at 23 °C the loss modulus G” determined by viscosity measurement is greater than the storage modulus G' of the component or mass in question.

[0023] The compositions are considered "curable" within the meaning of the invention if, under the curing conditions, solid and polymeric structures form beyond the gel point. The gel point is the point at which the storage modulus G' becomes equal to the loss modulus G".

[0024] Where the indefinite article “ein” or “eine” is used, this also includes the plural form “ein or mehr” unless this is expressly excluded.

[0025] "At least difunctional" means that each molecule contains two or more units of the respective functional group. No distinction is made between primary, secondary, or tertiary functional groups.

[0026] The compositions according to the invention can be single-component or multi-component. The composition according to the invention is preferably single-component.

[0027] “One-component” or “one-component mass” means that the reactive components of the mass are present together and mixed together in one packaging unit.

[0028] All weight proportions listed below refer to the total weight of all components of the mass, excluding additives, unless otherwise stated.

[0029] Component (A): Thioether compound

[0030] The compositions according to the invention contain as component (A) at least one thioether compound, wherein the thioether compound comprises at least one at least difunctional cyclic thioether.

[0031] In other words, component (A) comprises at least one compound comprising at least two cyclic thioethers as functional groups, for example at least two thiirane or thietane groups.

[0032] The term "thioether compound" is therefore used here and below to refer to a compound that has a cyclic thioether as a functional group. Suitable thioether compounds (A) are not further restricted structurally and can be aromatic, aliphatic, or cycloaliphatic thioether compounds.

[0033] In particular, the thioether compound comprises one or more at least difunctional thiiranes (A1) and / or one or more at least difunctional thietanes (A2).

[0034] The thioether compound preferably comprises one or more at least difunctional thiiranes (A1).

[0035] Due to their significantly reduced ring strain and the associated lower reactivity, the longer-chain thiolanes, thianes, thiepanes are not preferred as thioether compounds (A).

[0036] Based on the total weight of the mass, apart from additives, component (A) is preferably present in a proportion of 15 to 99 percent by weight, particularly preferably in a proportion of 25 to 98 percent by weight.

[0037] Component (A1): Thiirane

[0038] Component (A) comprises, in particular, at least one thiirane (A1) as a thioether compound, which is at least difunctional. The use of an at least difunctional thiirane (A1) allows for higher crosslinking of the compositions than with a monofunctional thiirane (A1). Furthermore, difunctional thiiranes (A1) allow for the production of more highly crosslinked compositions than would be possible with polyfunctional initiators.

[0039] The at least difunctional thiirane (A1) is preferably present in a proportion of at least 5 percent by weight, based on the total weight of component (A1), more preferably at least 10 percent by weight, particularly preferably at least 15 percent by weight.

[0040] In addition to the at least difunctional thiirane (A1), component (A1) may contain a monofunctional thiirane (A1).

[0041] The monofunctional thiirane (A1) is preferably present in a proportion of at most 95 percent by weight, based on the total weight of component (A1), more preferably at most 90 percent by weight, particularly preferably at most 85 percent by weight.

[0042] Preferred examples of thiiranes (A1) include compounds obtained by replacing one or more epoxide groups with thiirane groups.

[0043] Starting compounds include bisphenol A epoxy resins, bisphenol F epoxy resins, biphenyl glycidyl epoxy resins,

[0044] Naphthalenediol diglycidyl ether, glycidyl ether of tris(hydroxyphenyl)methane and glycidyl ether of tris(hydroxyphenyl)ethane, and mixtures thereof.

[0045] Furthermore, all fully or partially hydrogenated analogues of aromatic epoxy resins can be used as starting compounds.

[0046] Examples of suitable thiiranes (A1) are listed below.

[0047] Examples of monofunctional thiiranes (A1) are phenyl epithiopropyl ether, 4-tert-butylphenyl epithiopropyl ether, neodecanoic acid epithiopropyl ester, butyl epithiopropyl ether, 2-ethylhexyl epithiopropyl ether, cresyl epithiopropyl ether, cardanyl epithiopropyl ether.

[0048] Examples of commercially available monofunctional epoxides from which the analogous thiiranes (A1 ) can be obtained include products sold under the trade names Glycirol ED 509-S by Adeka, DER 727 by Olin, Heloxy Modifier AQ by Hexion, Cardolite Ultra Lite 513 by Cardolite or iPox RD 17 by iPox Chemicals GmbH.

[0049] Examples of di- and higher functional aromatic thiiranes (A1) include 1,3- and 1,4-bis(epithioethyl)benzene, bis[4-(epithioethyl)phenyl]methane, 2,2-bis[4-(epithioethyl)phenyl]propane, bis[4-(epithioethyl)phenyl]sulfide, bis[4-(epithioethyl)phenyl]sulfone, 4,4'-bis(epithioethyl)biphenyl, 1,3- and 1,4-bis(epithiopropyloxy)benzene, 1,3- and 1,4-bis(epithiopropyloxymethyl)benzene, bis[4-(epithiopropyloxy)phenyl]methane, 2,2-bis[4-

[0050] (epithiopropyloxy)phenyl]propane, bis[4-(4-epithiopropyloxy)phenyl]sulfide, bis[4-(epithiopropyloxy)phenyl]sulfone, and 4,4'-bis(epithiopropyloxy)biphenyl. Examples of commercially available aromatic epoxy compounds from which the analogous thiiranes (A1) can be obtained include products sold under the trade names Epikote Resin 828 LVEL, Epikote Resin 166, and Epikote Resin 169 by Hexion Specialty Chemicals BV, the Netherlands, or as EPICLON™ 840, 840-S, 850, 850-S, EXA850CRP, and 850-LC by DIC KK, Japan.

[0051] Examples of di- and higher functional aliphatic thiiranes (A1) include 1,1-bis(epithioethyl)methane, 1,1-bis(epithiopropyl)methane, 1,2-

[0052] Bis(epithiopropyl)ethane, 1,3-bis(epithiopropyl)propane, 1,4-bis(epithiopropyl)butane, tetrakis-(epithiopropyl)methane, 1, 1, 1-tris(epithiopropyl)propane, 1,3-

[0053] Bis(epithiopropyl)-1-(epithiopropyl)-2-thiapropane and 1,5-Bis(epithiopropyl)-2,4- Bis(epithiopropyl)-3-thiapentane, Bis(epithiopropyl)ether,

[0054] Bis(epithiopropyloxy)methane, 1,2-Bis(epithiopropyloxy)ethane, 1,3-

[0055] Bis(epithiopropyloxy)propane, 1 ,2-Bis(epithiopropyloxy)propane, 1-

[0056] (Epithiopropyloxy)-2-(epithiopropyloxymethyl)propane, 1,4-

[0057] Bis(epithiopropyloxy)butane, 1 ,3-Bis(epithiopropyloxy)butane, l-(Epithiopropyloxy)- 3-(epithiopropyloxymethyl)butane, 1 ,5-Bis(epithiopropyloxy)pentane, 1-

[0058] (Epithiopropyloxy)-4-(epithiopropyloxymethyl)pentane, 1,6-

[0059] Bis(epithiopropyloxy)hexane, 1-(Epithiopropyloxy)-5-

[0060] (epithiopropyloxymethyl)hexane, 1 -(Epithiopropyloxy)-2-[(2-

[0061] (epithiopropyloxyethyl)oxy]ethane, 1-(Epithiopropyloxy)-2-[[2-(2- epithiopropyloxyethyl)oxyethyl]oxy]ethane, Tetrakis-

[0062] ([epithiopropyloxymethyl)methane, 1 , 1 , 1-Tris([epithiopropyloxymethyl)propane, 1 ,5- Bis(epithiopropyloxy)-2-(epithiopropyloxymethyl)-3-thiapentane, 1 ,5-

[0063] Bis(epithiopropyloxy)-2,4-bis(epithiopropyloxymethyl)-3-thiapentane, 1-

[0064] (Epithiopropyloxy)-2,2-bis(epithiopropyloxymethyl)-4-thiahexane, 1,5,6-

[0065] Tris(epithiopropyloxy)-4-(epithiopropyloxymethyl)-3-thiahexane, 1,8-

[0066] Bis(epithiopropyloxy)-4-(epithiopropyloxymethyl)-3,6-dithiaoctane, 1,8-

[0067] Bis(epithiopropyloxy)-4,5-bis(epithiopropyloxymethyl)-3,6-dithiaoctane, 1,8-

[0068] Bis(epithiopropyloxy)-4,4-bis(epithiopropyloxymethyl)-3,6-dithiaoctane, 1 ,8-

[0069] Bis(epithiopropyloxy)-2,4,5-tris(epithiopropyloxymethyl)-3,6-dithiaoctane, 1 ,8-

[0070] Bis(epithiopropyloxy)-2,5-bis(epithiopropyloxymethyl)-3,6-dithiaoctane, 1 ,9-

[0071] Bis(epithiopropyloxy)-5-([epithiopropyloxymethyl)-5-[(2- epithiopropyloxyethyl)oxymethyl]-3,7-dithianonan, 1 ,10-Bis(epithiopropyloxy)-5,6- Bis[(2-epithiopropyloxyethyl)oxy]-3,6,9-trithiadecane, 1 ,11-Bis([epithiopropyloxy)- 4,8-bis(epithiopropyloxymethyl)-3,6,9-trithiaundecane, 1 ,11-Bis(epithiopropyloxy)-

[0072] 5.7-bis(epithiopropyloxymethyl)-3,6,9-trithiaundecane, 1 ,11-Bis(epithiopropyloxy)-

[0073] 5.7-[(2-[epithiopropyloxyethyl)oxymethyl)-3,6,9-trithiaundecan und 1,11-

[0074] Bis(epithiopropyloxy)-4,7-bis(epithiopropyloxymethyl)-3,6,9-trithiaundecane.

[0075] Examples of commercially available di- or higher-functional aliphatic epoxy compounds from which the analogous thiiranes (A1) can be obtained include products sold under the trade names iPox RD21, iPox CL60, iPox CL9 by ipox Chemicals GmbH or YED-216D by Mitsubishi Chemical, Japan or Heloxy Modifier HD by Hexion or Araldite DY 3601 by Huntsman.

[0076] Beispiele für di- und höherfunktionelle cycloaliphatische Thiirane (A1) umfassen 1 ,3- und 1 ,4-Bis(epithioethyl)cyclohexan, Bis[4- (epithioethyl)cyclohexyl]methan, Bis[4-(epithiopropyl)cyclohexyl]methan, 2,2- Bis[4-(epithioethyl)cyclohexyl]propan, Bis[4-(epithiopropyl)cyclohexyl]sulfid, Bis[4- (epithioethyl)cyclohexyl]sulfid, 2,5-Bis(epithioethyl)-1 ,4-dithian, 2,5- Bis(epithiopropyl)- 1 ,4-dithian, 4- Epithioethyl- 1 ,2-cyclohexensulfid, 4-Epoxy-1 ,2- cyclohexenesulfid, 1 ,3- und 1 ,4-Bis(epithiopropyloxy)cyclohexan, 1 ,3- und 1 ,4- Bis(epithiopropyloxymethyl)cyclohexan, Bis[4-

[0077] (epithiopropyloxy)cyclohexyl]methan, 2,2-Bis[4-

[0078] (epithiopropyloxy)cyclohexyl]propan, Bis[4-(epithiopropyloxy)cyclohexyl]sulfid, 2,5-Bis(epithiopropyloxymethyl)-1 ,4-dithian und 2,5-

[0079] Bis((epithiopropyloxyethyloxymethyl)-1 ,4-dithian, sowie die Isomere des Dicyclopentadienedimethanolbisepithiopropylethers.

[0080] Examples of commercially available cycloaliphatic epoxy compounds from which the analogous thiiranes (A1) can be obtained include products sold under the trade names CELLOXIDE 2021 P, CELLOXIDE 8000 from Daicel Corporation, Japan or Omnilane 1005, Omnilane 2005, Omnilane OC 3005 from IGM Resins BV or TTA21, TTA26 and TTA60 from Jiangsu Tetra New Material Technology Co. Ltd. or Syna Epoxy 21 from Synasia Inc. or THI-DE, DE-102, DE-103 from EN EOS Corporation. The examples of (A1) also include compounds obtained by replacing at least one hydrogen of the ethylene sulfide group with an alkyl or aryl group which may optionally be substituted, for example by replacing at least one hydrogen of the ethylene sulfide group with a methyl group.

[0081] Component (A2): Thietane

[0082] Thietanes (A2) can also be used as thioether compounds of component (A) in the compositions according to the invention.

[0083] These can be produced, for example, by reacting suitable precursor compounds such as thietan-3-one, 3-thietanol, 3-mercaptothietane or 3-chlorothietane.

[0084] Di- and higher-functional thietanes (A2) can also be advantageously used in the compositions according to the invention.

[0085] The combination of thiirane and thietane groups is also possible.

[0086] Examples of thietane syntheses can be found in US Pat. Nos. 8,362,280 B2 and 7,132,501 B2. The thietanes described therein are also suitable as thietanes (A2) in the compositions of the invention.

[0087] Suitable thietanes (A2) are, for example, 3,3'-[oxybis(methylene)]bis(3-ethylthietane), 3-[(allyloxy)methyl]-3-ethylthietane, 3-ethyl-3-

[0088] (phenoxymethyl)thietane, (3-ethylthietan-3-yl)methanol, 1,4-bis{[(3-ethylthietan-3-yl)methoxy]methyl}benzene and 3-ethyl-3-{[(2-ethylhexyl)oxy]methyl}thietane.

[0089] Examples of commercially available oxetanes from which the analogous thietanes (A2) can be obtained are bis(1-ethyl-3-oxetanyl-methyl) ether (DOX), 3-allyloxymethyl-3-ethyloxetane (AQX), 3-ethyl-3-(phenoxymethyl)oxetane (POX), 3-ethyl-3-hydroxymethyl-oxetane (OXA), 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene (XDO), and 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane (EHOX). These oxetanes are commercially available from TOAGOSEI CO., Ltd.

[0090] The proportion of thietane (A2) in component (A) is preferably in a range from 0 to 80 percent by weight, particularly preferably in a range from 0 to 50 percent by weight, in each case based on the total weight of component (A).

[0091] Component (A3): Hybrid compounds

[0092] Component (A) may further comprise hybrid compounds (A3) which, in addition to at least one cyclic thioether group, have further crosslinkable functional groups, such as, for example, (meth)acrylates, isocyanates, oxetanes, hydroxyl groups or epoxides.

[0093] In particular, the hybrid compounds (A3) have at least one thiirane and / or thietane group as cyclic thioether group.

[0094] Hybrid compounds (A3) can be obtained, for example, by partial reaction of at least difunctional cyclic thioethers with compounds which have a further addition-crosslinkable group.

[0095] Another possibility is the reaction of isocyanato(meth)acrylates with compounds that contain an isocyanate-reactive group in addition to a thiirane and / or thietane group.

[0096] The conversion of hybrid functional epoxides and / or oxiranes to the analogous thiiranes and / or thietanes as well as the partial replacement of the oxygen of at least difunctional epoxides or oxiranes by sulfur is also possible.

[0097] The hybrid compounds (A3) preferably contain, in addition to at least one cyclic thioether group, an additional radically curable group. Thiirane-(meth)acrylate hybrid compounds are particularly preferred within the meaning of the invention.

[0098] Examples of commercially available epoxy (meth)acrylates from which the analogous thiiranes can be obtained are CYCLOMER M100 from Daicel, Epoxy Acrylate Solmer SE 1605, UVACURE 1561 from UCB, Miramer PE210HA from Miwon Europe GmbH, and Solmer PSE 1924 from Soltech Ltd. Oxetane (meth)acrylates such as Eternacoll OXMA from UBE Industries LTD can also be used to synthesize the hybrid compound (A3). The presence of hybrid compounds (A3) enables additional crosslinking of the materials. Other curing mechanisms that can occur in addition to the polyinsertion reaction include radical polymerization, cationic or anionic polymerization, polyaddition, and polycondensation.

[0099] The proportion of hybrid compounds (A3) in component (A) is preferably in a range from 0 to 90 percent by weight, particularly preferably in a range from 0 to 50 percent by weight, in each case based on the total weight of component (A).

[0100] Component (B): Initiator

[0101] In addition to the thioether (A), the compositions according to the invention contain at least one initiator (B) which contains a functional group suitable for the polyinsertion of component (A).

[0102] The use of the at least difunctional cyclic thioether in combination with an initiator (B) is essential to the invention and leads to branched polymer chains.

[0103] In the broadest sense, the initiator (B) is characterized in that the functional group suitable for the polymerization is retained in its structure by insertion of the thioether compound (A) and can undergo further insertions.

[0104] Preferred initiators (B) are all compounds containing a (thio)carbonylthio group. Compounds containing a (thio)carbonylthio group include all compounds containing a dithioester group (thiocarbonylthio group) or a thiolic acid ester group (carbonylthio group). These are not further restricted structurally. The (thio)carbonylthio group can be linear, cyclically bridged, or present in prepolymeric and / or oligomeric compounds.

[0105] The essential functional unit of initiator (B) is a (thio)carbonylthio group. Without being bound to any scientific theory, the successful reaction mechanism of such an initiator (B) with a cyclic thioether is attributed to the fact that the (thio)carbonyl-sulfur bond is ruptured by attack of a thiolate anion formed from the cyclic thioether. At the same time, a new (thio)carbonyl-sulfur bond is formed, and the monomer is inserted. The central functional unit remains intact and is available for the insertion of another monomer selected from component (A).

[0106] Initiators (B) suitable for the purposes of the invention are derived, for example, from thiolic acid esters, dithioesters, dithiocarbonates (xanthates), trithiocarbonates and the sulfur-bridged thiourethanes, including thiourethanes and dithiourethanes (dithiocarbamates).

[0107] Preferably, the initiator (B) is a cyclic initiator (B1).

[0108] Selected cyclic compounds suitable as cyclic initiators (B1) are γ-thiobutyrolactone, 2,4-thiazolidinedione, 2-thioxothiazolidin-4-one (rhodanine) as well as rhodanines substituted with aliphatic or aromatic groups, such as 3-ethyl-2-thioxothiazolidin-4-one or 3-benzyl-2-thioxothiazolidin-4-one.

[0109] The preferred cyclic initiator (B1) is 2,4-thiazolidinedione.

[0110] In addition to cyclic initiators (B1), linear initiators (B2) can also be used in the compositions according to the invention. Suitable examples are dibenzyl trithiocarbonate, S,S'-dimethyl dithiocarbonate,

[0111] S-butylbenzoylcarbamothioate or 1,3,5-tris(3-acetylmercaptopropyl)-1,3,5-triazine-2,4,6-trione.

[0112] By selecting different initiators (B), the curing speed of the liquid mass and the mechanical properties of the cured mass can be controlled.

[0113] The use of linear initiators (B2) using a thioether compound (A) leads to the extension of the initiator molecule with the formation of a polythioether chain.

[0114] The use of cyclic initiators (B1) leads to the formation of macrocyclic polythioether structures. As with the linear initiators (B2), the degree of crosslinking of the cyclic polythioethers can be controlled by the content of the at least difunctional cyclic thioether. The degree of crosslinking can be adjusted over a wide range by selecting suitable amounts of the at least difunctional cyclic thioether, thus enabling a comprehensive range of properties to be achieved.

[0115] Both the slightly branched and the highly branched polythioethers are suitable for use as adhesive, potting or coating materials in cured form.

[0116] The use of cyclic initiators (B1) is preferred over linear initiators (B2) with regard to the curing rate, with cyclic initiators (B1) causing a higher curing rate than linear initiators (B2).

[0117] The use of initiators (B) bearing more than one (thio)carbonylthio group is also within the scope of the invention. Difunctional or higher-functional initiators, in particular, offer the possibility of advantageously controlling the reactivity of the compositions and adjusting the flexibility of the cured compositions.

[0118] Furthermore, initiators (B) that contain, in addition to a (thio)carbonylthio group in a cyclic arrangement, another non-cyclic (thio)carbonylthio group in the same molecule can be advantageously used. Such compounds can be considered a combination of a cyclic initiator (B1) and a linear initiator (B2).

[0119] The use of mixed-functionality initiators (B3) is also within the scope of the invention. Such initiators contain, in addition to at least one (thio)carbonylthio group, another functional group that is preferably curable. For example, (meth)acrylate-functional initiators (B3) are also within the scope of the invention.

[0120] By adding photoinitiators for radical polymerization in combination with (meth)acrylate-functional initiators (B3), masses can be obtained that are additionally light-fixable.

[0121] The initiator (B) can also be an oligomeric thioether compound (B4), provided that it has a (thio)carbonylthio group.

[0122] The use of oligomeric thioether compounds (B4) allows, in particular, the mechanical properties and adhesion of the cured masses to be adjusted. In principle, the use of oligomeric thioether compounds (B) also allows the construction of more complex polymer structures, for example, a block copolymer.

[0123] Such oligomeric thioether compounds (B4) are obtainable by prepolymerization. For this purpose, the initiator (B) is reacted with a thioether compound (A) in a suitable equivalent ratio, so that the compound obtained in the reaction can subsequently be further polymerized and converted into a cured state.

[0124] For this purpose, preferably 1 to 50 equivalents, particularly preferably 2 to 40 equivalents of the thioether compound (A) are reacted with one equivalent of the initiator (B).

[0125] Here and below, "equivalent" refers to the number of respective functional groups in the corresponding component, with reference to the functional group required for the respective reaction. Thus, the equivalent of thioether compound (A) refers to the respective thioether group of the thioether compound, and the equivalent of initiator (B) refers to the functional group that is suitable for polymerization by insertion of the thioether compound (A), retains its structure, and can thus undergo further insertions, preferably to the (thio)carbonylthio group of initiator (B).

[0126] The term “equivalents” is not further limited and includes compounds with more than one functional group within a molecule, as well as a plurality of single-functional compounds and / or mixtures thereof.

[0127] The oligomeric thioether compound (B4) is preferably in liquid form.

[0128] The equivalent ratio (A) to (B) can also influence the ring size and / or the chain length of the polythioethers.

[0129] The thioether compound (A) is preferably used in a ratio of 5 to 300 equivalents, more preferably 8 to 250 equivalents, particularly preferably 10 to 200 equivalents, based in each case on one equivalent of the functional group of the initiator (B). Based on the total weight of the composition, excluding additives, component (B) is preferably present in a proportion of 0.1 to 20 weight percent, particularly preferably in a proportion of 0.3 to 10 weight percent.

[0130] Component (C): Catalyst

[0131] In addition to the thioether compound (A) and the initiator (B), the compounds also contain at least one catalyst (C). This accelerates the polymerization and allows the curing temperature of the compound to be adjusted.

[0132] The catalyst (C) can be selected from the group of non-ionic compounds (C1), such as Lewis acid-base adducts, and ionic compounds (C2), including ionic liquids and zwitterionic compounds.

[0133] Examples of non-ionic catalysts (C1) are the adducts of boranes and boron trihalides with diethyl ether, tetrahydrofuran or dimethyl sulfide.

[0134] Zwitterionic compounds suitable as catalysts (C2) include, for example, betaines, amino acids or carnitine.

[0135] Suitable catalysts (C2) can further be selected from the group of quaternary ammonium salts, quaternary phosphonium salts, tertiary sulfonium salts and / or secondary iodonium salts.Bevorzugt eingesetzt werden quartäre Ammoniumsalze wie beispielsweise Tetramethylammonium, Tetraethylammonium, Tetra-n-butylammonium, Tetra-n-hexylammonium, Tetra-n- octylammonium, T rimethyl-n-octylammonium, T rimethylbenzylammonium, T riethyl-n-octylammonium, T riethylbenzylammonium, T ri-n-butyl-n- octylammonium, Tri-n-butylbenzylammonium, Methyltriphenylammonium, Ethyltriphenylammonium, n-Butyltriphenylammonium, n-Butyltriphenylammonium, 1-Methylpyridinium, 1 -Ethylpyridinium, 1-n-Butylpyridinium, 1-n-Hexylpyridinium, 1-n-Octylpyridinium, 1-Butyl-3-methylpyridinium, 1-n-Dodecylpyridinium, 1-n- Phenylpyridinium, 1-Butyl-1-methylpyrrolidinium, 1-Methylpicolinium, 1- Ethylpicolinium, 1-n-Butylpicolinium, 1-n-Hexylpicolinium, 1-n-Octylpicolinium, 1-n- Dodecylpicolinium, 1-Phenylpicolinium, 1-Ethyl-3-methylimidazolium, 1-Butyl-2,3- dimethylimidazolium, und 1-Hexyl-3-methyl-imidazolium.Ammonium salts, which are formally obtained by alkylation of amines, are particularly preferably used as catalyst (C2).

[0136] Possible counterions include trifluoromethanesulfate, p-toluenesulfonate, p-nitrophenoxide, hydrogensulfate, phosphate, hexafluorophosphate, thiocyanate, salicylate, acetate, propionate, hexanoate, 2-ethylhexanoate, tetrafluoroborate, tetrakis(pentafluorophenyl)borate, tetraphenylborate, hydroxide or halides.

[0137] Beispiele für geeignete Katalysatoren sind Tetramethylammoniumchlorid, Tetramethylammoniumbromid, T etramethylammoniumacetat, Tetraethylammoniumchlorid, Tetraethylammoniumbromid, Tetraethylammoniumacetat, Tetra-n-butylammoniumfluorid, Tetra- n- butylammoniumchlorid, Tetra- n-butylammoniumbromid, Tetra-n- butylammoniumiodid, Tetra-n-butylammoniumacetat, Tetra-n- butylammoniumborhydrid, Tetra-n-butylammonium hexafluorophosphit, Tetra-n- butylammoniumhydrogensulfit, Tetra-n-butylammoniumtetrafluoroborat, Tetra-n- butylammoniumtetraphenylborat, Tetra-n-butylammonium-p-toluolsulfonat, Tetra- n-butylammoniumsalicylat T etra-n-hexylammoniumchlorid, Tetra-n- hexylammoniumbromid, T etra-n-hexylammoniumacetat, Tetra-n- octylammoniumchlorid, T etra-n-octylammoniumbromid, Tetra- n- octylammoniumacetat, Trimethyl-n-octylammoniumchlorid, T rimethylbenzylammoniumchlorid, T rimethylbenzylammoniumbromid, T riethyl-n- octylammoniumchlorid, T riethylbenzylammoniumchlorid, T riethylbenzylammoniumbromid,T ri-n-butyl-n-octylammoniumchlorid, T ri-n- butylbenzylammoniumfluorid, T ri-n-butylbenzylammoniumchlorid, T ri-n- butylbenzylammoniumbromid, T ri-n-butylbenzylammoniumiodid, Methyltriphenylammoniumchlorid, Methyltriphenylammoniumbromid, Ethyltriphenylammoniumchlorid, Ethyltriphenylammoniumbromid, n-,

[0138] Butyltriphenylammoniumchlorid, n-Butyltriphenylammoniumbromid, 1 -Butyl-2,3- dimethylimidazoliumchlorid, 1-Butyl-1-methylpyrrolidiniumchlorid, 1-Butyl-3- methylpyridiniumchlorid, 1-Methylpyridiniumchlorid, 1-Methylpyridiniumbromid,

[0139] 1-Ethylpyridiniumchlorid, 1-Ethylpyridiniumbromid, 1-n-Butylpyridiniumchlorid, 1-n-

[0140] Butylpyridiniumbromid, 1-n-Hexylpyridiniumchlorid, 1-n-Hexylpyridiniumbromid, 1- n-Octylpyridiniumchlorid, 1-n-Octylpyridiniumbromid, 1-n-

[0141] Dodecylpyridiniumchlorid, 1-n-Dodecylpyridiniumbromid, 1-n-

[0142] Phenylpyridiniumchlorid, 1-n-Phenylpyridiniumbromid, 1-Methylpicoliniumchlorid, 1-Methylpicoliniumbromid, 1-Ethylpicoliniumchlorid, 1-Ethylpicoliniumbromid, 1-n- Butylpicoliniumchlorid, 1-n-Butylpicoliniumbromid, 1-n-Hexylpicoliniumchlorid, 1-n- Hexylpicoliniumbromid, 1-n-Octylpicoliniumchlorid, 1-n-Octylpicoliniumbromid, 1- n-Dodecylpicoliniumchlorid, 1-n-Dodecylpicoliniumbromid, 1-

[0143] Phenylpicoliniumchlorid und 1-Phenylpicoliniumbromid.

[0144] Beispiele ffür quartäre Phosphoniumsalze sind Tetramethylphosphoniumchlorid, Tetramethylphosphoniumbromid, Tetraethylphosphoniumchlorid, T etraethylphosphoniumbromid, Tetra- n-butyl- phosphoniumchlorid, T etra-n-butylphosphoniumbromid, Tetra-n-butyl- phosphoniumiodid, Tetra- n-hexylphosphoniumbromid, Tetra-n-octyl- phosphoniumbromid, Methyltriphenylphosphoniumbromid, Methyltriphenyl- phosphoniumiodid, Ethyltriphenylphosphoniumbromid, Ethyltriphenyl- phosphoniumiodid, n-Butyltriphenylphosphoniumbromid, n-Butyltriphenyl- phosphoniumiodid, n-Hexyltriphenylphosphoniumbromid, n-Octyltriphenyl- phosphoniumbromid, Tetraphenylphosphoniumbromid, Tetrakishydroxymethyl- phosphoniumchlorid, Tetrakishydroxymethylphosphoniumbromid, Tetrakis- hydroxyethylphosphoniumchlorid und T etrakishydroxybutylphosphoniumchlorid.

[0145] Examples of tertiary sulfonium salts are trimethylsulfonium bromide, triethylsulfonium bromide, tri-n-butylsulfonium chloride, tri-n-butylsulfonium bromide, tri-n-butylsulfonium iodide, tri-n-butylsulfonium tetrafluoroborate, tri-n-hexylsulfonium bromide, T ri-n-octylsulfonium bromide, triphenylsulfonium chloride, triphenylsulfonium bromide and triphenylsulfonium iodide.

[0146] Examples of secondary iodonium salts are diphenyliodonium chloride, diphenyliodonium bromide and diphenyliodonium iodide.

[0147] The catalyst (C) may be a single compound or a combination of several compounds.

[0148] Based on the total weight of the mass, apart from additives, component (C) is preferably present in a proportion of 0.01 to 10 percent by weight, particularly preferably in a proportion of 0.02 to 5 percent by weight.

[0149] The catalyst (C) is preferably used in a ratio of 0.001 to 10 equivalents, particularly preferably 0.005 to 5 equivalents, in each case based on one equivalent of the functional group of the initiator (B).

[0150] Avoiding halogen-containing catalysts (C) can be advantageous for applications in the electronics sector.

[0151] Component (D): Radically curable compounds

[0152] Optionally, the composition according to the invention contains, in addition to components (A) to (C), further radically curable compounds (D) which can be radically polymerized by irradiation with actinic radiation or by introduction of heat.

[0153] The radically curable compounds (D) are preferably compounds based on (meth)acrylates and (meth)acrylamides. These are not further restricted in their chemical structure. For example, both aliphatic and aromatic (meth)acrylates and (meth)acrylamides can be used.

[0154] Here and in the following, (meth)acrylates and (meth)acrylamides refer to both the derivatives of acrylic acid and methacrylic acid as well as combinations and mixtures thereof.

[0155] The radically curable compounds (D) can be used to achieve rapid light fixation by irradiating the masses with actinic radiation.

[0156] Furthermore, the radically curable compounds (D) can be used to advantageously influence the dosing properties of the curable masses.

[0157] Preferably, the radically curable compound (D) comprises at least one difunctional compound.

[0158] Suitable, for example, are the following radically curable compounds (D): isobornyl acrylate, stearyl acrylate, tetrahydrofurfuryl acrylate, cyclohexyl acrylate, 3,3,5-trimethylcyclohexanol acrylate, behenyl acrylate, 2-methoxyethyl acrylate and other mono- or polyalkoxylated alkyl acrylates, isobutyl acrylate, isooctyl acrylate, lauryl acrylate, tridecyl acrylate, isostearyl acrylate, 2-(o-phenylphenoxy)ethyl acrylate, acryloylmorpholine, N,N-dimethylacrylamide, 4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,10-decanediol diacrylate, tricyclodecanedimethanol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polybutadiene diacrylate, cyclohexanedimethanol diacrylate, Diacrylates and diurethane acrylates of monomeric, oligomeric or polymeric diols and polyols, polytetramethylene glycol dimethacrylate,

[0159] Trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTMA), and dipentaerythritol hexaacrylate (DPHA), and combinations thereof. Higher-functional acrylates derived from multiply branched or dendrimeric alcohols can also be used advantageously.

[0160] The analogous methacrylates are also within the meaning of the invention.

[0161] Radically curable compounds (D) containing allyl groups, such as 1,3,5-triallyl-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, which is commercially available as TAICROS®, are also suitable. Unhydrogenated polybutadienes with free double bonds, such as the Poly BD® grades, can also be used as radically curable compounds (D).

[0162] As higher molecular weight radically curable compounds (D), acrylates and urethane acrylates based on polyesters, polyethers, polycarbonate diols, polybutadiene diols and / or hydrogenated polybutadiene diols can be used as component (D).

[0163] A combination of several radically curable compounds (D) is also within the meaning of the invention.

[0164] The radically curable compounds (D) are preferably present in the composition according to the invention in a proportion of up to 50 percent by weight, particularly preferably in a proportion of up to 30 percent by weight, in each case based on the total weight of the composition, apart from additives.

[0165] Component (E): Initiator for radical polymerization

[0166] In addition to components (A) to (D), the compositions optionally contain an initiator (E) for activating the radical polymerization, preferably a photoinitiator (E1).

[0167] As photoinitiators (E1) the usual, commercially available compounds can be used, such as, for example, a-hydroxy ketones, benzophenone, a,a'-diethoxyacetophenone, 4,4-diethylaminobenzophenone, 2,2-dimethoxy-2-phenyl-acetophenone, 4-isopropylphenyl-2-hydroxy-2-propyl ketone, 1-hydroxy-cyclohexylphenyl ketone, isoamyl-p-dimethylaminobenzoate, methyl-4-dimethyl-aminobenzoate, 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-trimethylbenzoyl-diphenylphosphine oxide and bisacylphosphine oxides, wherein the photoinitiators mentioned alone or in combination of two or more of the compounds mentioned can be used.

[0168] As UV photoinitiators (E1) for radical polymerization, for example, the IRGACURE™ types from BASF SE can be used, such as the types IRGACURE 184, IRGACURE 500, IRGACURE 1179, IRGACURE 2959, IRGACURE 745, IRGACURE 651, IRGACURE 369, IRGACURE 907, IRGACURE 1300, IRGACURE 819, IRGACURE 819DW, IRGACURE 2022, IRGACURE 2100, IRGACURE 784, IRGACURE 250, IRGACURE TPO, IRGACURE TPO-L

[0169] Furthermore, DAROCUR® grades from BASF SE can be used, such as DAROCUR MBF, DAROCUR 1173, DAROCUR TPO and DAROCUR 4265.

[0170] The photoinitiator (E1) used as component (E) in the compositions according to the invention can preferably be activated by irradiation with actinic radiation having a wavelength of 200 to 480 nm, particularly preferably 250 to 400 nm.

[0171] The initiator (E) for activating the radical polymerization is preferably present in the composition according to the invention in a proportion of 0 to 5 percent by weight, particularly preferably in a proportion of 0.01 to 3 percent by weight, based on the total weight of the composition, apart from additives.

[0172] Furthermore, the initiator for the radical polymerization (E) may comprise a thermal initiator (E2) which can be activated by heating to a predetermined temperature.

[0173] The thermal initiator (E2) ensures complete curing of the radically curable compounds (D). Pure heat curing of the radically curable component (D) is also within the scope of the invention. In this case, the initiator for the radical polymerization (E) can consist of component (E2).

[0174] The additional thermal initiator (E2) preferably comprises one or more peroxo compounds. These can be selected, for example, from the group of peroxo(di)esters, hydroperoxides, (di)alkyl peroxides, ketone peroxides, perketals, peracids, peroxomonocarbonates, and peroxodicarbonates. The use of thermal initiators (E2) selected from the group of azo compounds or benzpinacols is also possible.

[0175] The thermal initiator (E2) is present in the compositions according to the invention in a proportion of up to 100% by weight, preferably in a proportion of up to 90% by weight, more preferably in a proportion of up to 80

[0176] Percent by weight, particularly preferably in a proportion of up to 70

[0177] Percent by weight, based on component (E).

[0178] Component (F): Additives

[0179] The masses described may also contain optional ingredients as additives (F).

[0180] The additives (F) are preferably selected from the group consisting of solvents, fillers, dyes, pigments, anti-aging agents, fluorescent agents, sensitizers, accelerators, stabilizers, adhesion promoters, drying agents, crosslinkers, flow improvers, wetting agents, thixotropic agents, non-reactive

[0181] Flexibilizers, non-reactive polymeric thickeners, flame retardants, corrosion inhibitors, plasticizers and combinations thereof.

[0182] Epoxies, for example, can be used as accelerators. The addition of epoxies can accelerate curing and lower the temperature required for curing.

[0183] The compositions of the invention may contain one or more addition-curing curing agents for component (A) as additive (F). The chemical nature of the curing agents is not further restricted. Examples of additional addition-curing curing agents include compounds such as thiols, anhydrides, amines, and / or polyols.

[0184] The crosslinkers are preferably at least difunctional.

[0185] The additives (F) are preferably present in the composition according to the invention in a proportion of up to 85 percent by weight, based on the total weight of the composition with all components.

[0186] Formulation of the compositions according to the invention

[0187] In a first preferred embodiment, the composition comprises or consists of a) 15 to 99 percent by weight of the at least one thioether compound (A); b) 0.1 to 20 percent by weight of the initiator (B); and c) 0.01 to 10 percent by weight of the catalyst (C), each based on the total mass of components (A) to (C), wherein the proportions of components (A) to (C) add up to 100 percent by weight. In this embodiment, the composition, in particular, does not comprise the previously described components (D) and (E).

[0188] In a second preferred embodiment, the composition comprises or consists of a) 15 to 99 percent by weight of the at least one thioether compound (A); b) 0.1 to 20 percent by weight of the initiator (B); c) 0.01 to 10 percent by weight of the catalyst (C); d) 0 to 50 percent by weight of a radically curable compound (D); and e) 0 to 5 percent by weight of an initiator (E) for activating the radical polymerization, in each case based on the total mass of components (A) to (E), wherein the proportions of components (A) to (E) add up to 100 percent by weight. In both embodiments, the composition can preferably comprise up to 85 percent by weight of additives (F), based on the total weight of the composition.

[0189] In an advantageous embodiment, the amount of solvent required to dissolve and / or disperse the components of the composition, in particular the initiator (B) and / or the catalyst (C), can be reduced by using low-viscosity components in the composition. The radically curable compounds (D) are particularly suitable for this purpose.

[0190] In a preferred embodiment, the addition of solvents can be completely omitted. The term "solvent" refers to inert solvents in the composition that do not participate in a polymerization reaction.

[0191] Curing of the compositions according to the invention

[0192] At temperatures of 60 to 130 °C, the compositions according to the invention can be completely cured within 1 hour, preferably within 30 minutes.

[0193] Temperature-graded curing profiles are also within the scope of the invention. This means that the temperature at which the respective compound is cured is changed at least once during the curing process, disregarding unavoidable fluctuations.

[0194] Heating the mass for hardening can be done, for example, in a convection oven, by a thermode, an IR emitter, a laser, by microwaves or by induction.

[0195] The compositions according to the invention can exhibit an induction period if the respective composition is cured below its respective onset temperature at a constant temperature. The induction period is characterized by the fact that no measurable curing of the composition occurs during this period. This means that during the induction period (apart from unavoidable fluctuations), no significant reaction enthalpy and / or no increase in viscosity can be measured by means of differential scanning calorimetry (DSC) using dynamic differential calorimetry (DSC). Depending on the constant temperature below the onset temperature, the induction period can last up to 30 minutes, for example, 10 minutes or 20 minutes.

[0196] The subsequent cross-linking reaction following the induction period proceeds at a rate that is almost independent of temperature.

[0197] It is also possible to formulate the composition according to the invention as a pre-activatable composition. In this case, the composition is activated for curing by applying appropriate heat, and the heat source is then removed. After a predetermined waiting period, the compositions cure.

[0198] Use of the compositions according to the invention

[0199] The compositions according to the invention are particularly suitable for joining, casting, or coating substrates. Rapid curing at comparatively low temperatures allows for use with temperature-sensitive substrates.

[0200] Due to the formulation range of the compositions according to the invention, mechanical properties of a wide variety of applications can be represented, such as addition-curing adhesives, moisture-curing silicones or radical-curing systems.

[0201] Due to the low reaction enthalpy during curing of the compositions according to the invention, the use of fillers can optionally be dispensed with.

[0202] During the induction period, the constant temperature can further reduce the viscosity of the compound, thus improving its flow properties. These compounds are particularly suitable for casting small or complex geometries.

[0203] In particular, the previously described induction period can be advantageously used to perform a dosing and / or curing process that is spatially and temporally decoupled from the thermal activation without additional energy input. This enables, in particular, use in conjunction with temperature-sensitive substrates or joining partners, for example, based on polycarbonate. Processes using the compositions according to the invention

[0204] A method for producing a component using a curable composition as described above preferably comprises the following steps: a) metering the composition onto a first substrate; b) optionally supplying a second substrate to form a substrate composite comprising the first substrate and the second substrate, wherein the second substrate is brought into contact with the composition metered onto the first substrate; c) optionally irradiating the composition with actinic radiation to achieve a fixing strength sufficient for further processing of the first substrate or the substrate composite; and d) heating the optionally irradiated composition on the first substrate or in the substrate composite to a predetermined curing temperature, which leads to curing to form the component, wherein the component comprises the first substrate and a cured adhesive layer which is bonded to the first substrate and optionally to the second substrate.

[0205] The first substrate or the second substrate can be aligned relative to the other substrate after joining in step b) before fixing by irradiation of the mass.

[0206] In a first preferred embodiment, the predetermined curing temperature is equal to or greater than the onset temperature of the compound, also referred to as the curing temperature. In this variant, the compound is heated continuously until it cures.

[0207] In a further preferred embodiment, the heating of the mass in step d), also referred to as heat curing, takes place below the onset temperature of the mass at a constant temperature, also referred to as the induction temperature. In other words, the predetermined curing temperature is the induction temperature.

[0208] The induction temperature is preferably a temperature that is at most 30 °C below the onset temperature, particularly preferably at most 20 °C below the onset temperature. The selected induction temperature can be used to set an induction period of up to 30 minutes during which the inventive compound does not cure. This curing behavior allows for longer flow paths of the compound without the risk of premature curing in the component. The compound can thus be thermally preactivated.

[0209] In a third preferred embodiment, the heat curing in step d) takes place below the onset temperature, with the heat source for heating the compound being removed after a predetermined pre-activation time. After a predetermined waiting period, the compounds cure without the use of the heat source. This process makes it possible to subject the component to further optional process steps and / or to process it separately before final curing.

[0210] Instead of heating within a suitable container or reactor, heat input for heat curing below the onset temperature can also be achieved in a continuous flow. For example, applicators such as those used in the dispensing of hot melt adhesives are suitable for thermal pre-activation of the compositions of the invention.

[0211] In a further preferred embodiment, the light-fixing step c) follows only after the pre-activation of the mass according to step d). The advantage of this process is that the final curing of the mass after pre-activation and light-fixation takes place without further heat input.

[0212] Properties of the hardened masses

[0213] The compositions of the invention are suitable for joining, casting, and coating substrates. The diverse formulation options allow for a broad range of properties.

[0214] The compositions according to the invention are liquid at room temperature and are preferably formulated as a single component.

[0215] The compositions according to the invention are curable and form solid, polymeric structures under the described curing conditions. Even after exposure to temperature and humidity, the tensile strength of the cured compositions is essentially retained. If curing occurs below the onset temperature, the compositions exhibit an induction period of up to 30 minutes, during which they remain fully flowable. This allows for thermal pre-activation of the compositions.

[0216] The optional light fixation allows for high positioning accuracy of the joined components until final curing. Conventional fixation aids, which are particularly unsuitable for processing miniaturized components or would result in unreasonable additional effort, can thus be dispensed with.

[0217] The curing mechanism of ring expansion polymerization allows thioether compounds, especially thiiranes and thietanes, to be cured with sufficiently long processing times and low temperatures. These compounds exhibit a sharp curing profile combined with low reaction enthalpy, allowing them to be safely handled even in low-viscosity formulations with low filler quantities.

[0218] The reaction enthalpy is preferably below 450 J / g, more preferably below 300 J / g.

[0219] The polymer network formed during curing of the compositions according to the invention shows high resistance to temperature and media.

[0220] The use of hybrid compounds (A3) and / or mixed-functional initiators (B3) also makes it possible to connect polymer networks based on heat curing and light fixation as well as other optional polymer networks.

[0221] The compressive shear strength (DSF) on glass or aluminum is preferably at least 1 MPa, particularly preferably at least 10 MPa.

[0222] By adjusting the ring size and crosslink density, a broad mechanical spectrum is accessible. High-strength yet highly flexible materials can be formulated. The Young's modulus of the cured compounds can be adjusted over a range from 1 MPa to 10,000 MPa.

[0223] Further properties and features of the invention are described in detail and by way of example below with reference to preferred embodiments, which, however, should not be understood in a limiting sense.

[0224] Measurement methods and definitions used

[0225] Curing

[0226] "Crosslinking" or "curing" is defined as a polymerization, addition, or condensation reaction beyond the gel point. The gel point is the point at which the storage modulus G' becomes equal to the loss modulus G".

[0227] Irradiation

[0228] For 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 365 nm and an intensity of 200 ± 20 mW / cm 2 irradiated.

[0229] Room temperature

[0230] Room temperature is defined as 23 ± 2 °C.

[0231] Viscosity determination

[0232] The viscosity was measured using a Physica MCR302 rheometer from Anton Paar with a standardized measuring cone CP20-1 at 23 °C and determined at a shear rate of 10 / second.

[0233] Tensile strength

[0234] The tensile properties of Young's modulus, tensile strength, and elongation at break were determined in accordance with DIN EN ISO 527-2:2012-06. Type 5A specimens were used. The test was conducted at room temperature on a Zwick Roell Allround-Line 20 kN universal testing machine at a test speed of 1 mm / min. Curing was optionally performed by light fixation of the compound by sequential irradiation of both sides for 60 s each, with the specimen being turned after the first 60 s. Subsequent heat curing took place in a preheated convection oven at 100 °C for 45 min. After the test specimen mold had cooled, the specimen of the cured compound was removed from the mold and conditioned at room temperature for 24 hours.

[0235] Compressive Shear Strength (DSF) Two specimens (dimensions 20 mm x 20 mm x 5 mm) made of glass or laser-treated aluminum were bonded with a 5 mm overlap using the respective compound. For this purpose, a bead of the respective compound was applied to the first specimen and spread thinly. A second specimen was then bonded. The adhesive layer thickness of 0.1 mm and the overlap were adjusted using spacer wires and / or a bonding device. The bonded specimens were optionally illuminated at a wavelength of 365 nm for 60 s using a DELOLUX 20 / 365 LED lamp at an intensity of 200 mW / cm 2 irradiated. Subsequent heat curing took place in a preheated convection oven at 100 °C for 45 minutes. The specimens were conditioned at room temperature for 24 hours prior to testing.

[0236] Thermal DSC measurements

[0237] DSC measurements of reactivity are carried out in a differential scanning calorimeter (DSC) of type DSC2 or DSC3+ from Mettler Toledo.

[0238] 6 to 10 mg of the liquid sample were weighed into a 40 pL aluminum crucible with a pin, sealed with a lid, and subjected to a measurement over a temperature range of 30 to 230 °C at a heating rate of 5 K / min. Air was used as the process gas (flow rate 30 mL / min).

[0239] The onset, reaction enthalpy and peak temperature were evaluated.

[0240] The induction period was determined by an isothermal DSC measurement at 80 °C followed by a dynamic DSC measurement with a temperature range of 23 to 220 °C at a heating rate of 10 K / min.

[0241] If curing takes place at 80 °C without a measurable induction period or if this period lasts more than 30 minutes, a corresponding adjustment of the temperature of the isothermal DSC measurement may be necessary, for example with the aid of a dynamic DSC measurement.

[0242] Onset (corresponds to the induction period), peak time, reaction enthalpy, reaction conversion and residual enthalpy were evaluated.

[0243] Photo-DSC measurements: DSC measurements of the reactivity of the radiation-induced curing were performed in a Mettler Toledo DSC3+ differential scanning calorimeter (DSC). For this purpose, 6 to 10 mg of the liquid sample was weighed into a 40 pL aluminum crucible with a pin and irradiated at 365 nm for 10 minutes at 30 °C.

[0244] The peak time and the reaction enthalpy were evaluated after subtracting the energy input caused by the LED lamp.

[0245] Production of the hardenable masses

[0246] First, the liquid components were mixed, and then any fillers and optionally other solids were incorporated using a laboratory stirrer, laboratory dissolver, or a speed mixer (Hauschild) until a homogeneous mass was formed. Masses containing photoinitiators and sensitive to visible light must be prepared using light outside the excitation wavelength of the photoinitiators or sensitizers.

[0247] The masses thus produced were filled into single-chamber cartridges and sealed.

[0248] The following list shows all the compounds used in the examples for the preparation of the curable masses and their abbreviations:

[0249] Component (A): Thioether compound

[0250] (A1-1) difunctional thiirane based on hydrogenated bisphenol A

[0251] (A1-2) difunctional thiirane based on bisphenol F

[0252] (A1-3) difunctional thiirane based on bisphenol A

[0253] (A1-4) monofunctional thiirane based on 4-tert-butylphenyl glycidyl ether

[0254] (A1-5) monofunctional thiirane based on 2-ethylhexyl glycidyl ether

[0255] (A2-1) monofunctional thietane based on

[0256] Trimethylolpropane monoallyl ether

[0257] (A3-1) Hybrid compound based on 4-hydroxybutyl acrylate glycidyl ether Component (B): Initiator

[0258] (B1-1) cyclic initiator; 2,4-thiazolidinedione, available from TCI Deutschland GmbH

[0259] (B1-2) cyclic initiator; rhodanine, available from TCI Deutschland GmbH

[0260] (B1-3) cyclic initiator; 3-ethylrhodanine, available from TCI Deutschland GmbH

[0261] (B2-1) linear initiator; reaction product of one equivalent of 2,2-(ethylenedioxy)diethanethiol and two equivalents of 2-isocyanatoethyl methacrylate

[0262] (B2-2) linear initiator; reaction product of dibenzyl trithiocarbonate with n-butyl acrylate in a radical polymerization to form a polymer with an average molar mass of approximately M n = 2,700 g / mol.

[0263] Component (C): Catalyst

[0264] (C2-1) Tetra-n-butylammonium chloride, available from TCI Deutschland GmbH

[0265] (C2-2) Tetra-n-butylammonium acetate, available from Sigma-Aldrich Chemie GmbH

[0266] (C2-3) Tetra-n-butylammonium salicylate, available from TCI Deutschland GmbH

[0267] (C2-4) 1-Butyl-2,3-dimethylimidazolium chloride, available from TCI Deutschland GmbH

[0268] Component (D): Radically curable compound

[0269] (D1-1) 4-Acryloylmorpholine, available from RAHN GmbH

[0270] (D1-2) Trimethylolpropane trimethacrylate, available under the trade name Sartomer SR350D from ARKEMA FRANCE

[0271] (D1-3) Polytetramethylene glycol dimethacrylate, available under the trade name DIGL-6000-DMA from 3M Deutschland GmbH Component (E): Initiator for radical polymerization

[0272] (E1-1) 1-Hydroxycyclohexylphenyl ketone, available under the trade name Omnirad 184 from IGM Resins BV

[0273] (E2-1) TBPND, available from United Initiators Component (F): Additives

[0274] (F1-1) Propylene carbonate, available from BCD Chemie GmbH

[0275] (F1-2) Cab-O-Sil TS 382, ​​available from Cabot Corporation

[0276] (F1-3) Denka Fused Silica FB-74, available from Denki Kagaku Kögyö KK (F1-4) Denka Fused Silica FB-7SDC, available from Denki Kagaku

[0277] Kögyö KK

[0278] (F1-5) Denka Fused Silica SFP-30M, available from Denki Kagaku Kögyö KK

[0279] (F1-6) 3-Glycidyloxypropyltrimethoxysilane, available under the trade name Dynasylan GLYMO from Evonik Nutrition & Care GmbH

[0280] (F1-7) 2,2,6,6-Tetramethylpiperidine-1-oxyl, available under the trade name TEMPO from Sigma-Aldrich Chemie GmbH

[0281] (F1-8) jER YX 8000D = hydrogenated bisphenol-A epoxy resin, available from Mitsubishi Chemical

[0282] Table 1: Examples according to the invention.

[0283]

[0284] Table 2: Examples according to the invention with radical curing.

[0285]

[0286] Table 3: Further examples according to the invention with radical curing.

[0287]

[0288]

[0289] Table 4: Comparative examples.

[0290]

[0291]

[0292] The compositions according to Examples 1 to 19 demonstrate, by way of example and not exhaustively, the breadth of formulation possibilities of the composition of the invention. After curing, the compositions achieve a compressive shear strength of at least 1 MPa. The compositions according to Examples 9 to 19 contain free-radically curable components and can additionally be cured with actinic radiation.

[0293] The examples according to the invention consistently exhibit a low reaction enthalpy of less than 300 J / g. This allows for safe handling of the inventive compositions, for example, during production or shipping.

[0294] Examples according to the invention without specifying a curing time at 80 °C or an induction period at 80 °C require significantly higher temperatures for curing. Consequently, no corresponding measured values ​​were available under the defined test conditions.

[0295] The compositions according to Examples 1 to 3 each comprise an at least difunctional, cyclic thioether (A) in combination with an initiator (B) and a catalyst (C). At 80 °C, the compositions cure within seconds to a few minutes after an induction period and achieve tensile strengths of greater than 15 MPa.

[0296] Different catalysts (C) are used in the compositions according to Examples 4 and 5. The compositions exhibit comparable mechanical properties to the compositions according to Examples 1 to 3. The composition according to Example 4 achieves an induction period of greater than 20 minutes at 80 °C.

[0297] Example 6 uses a catalyst based on an imidazolium salt. Example 7 uses the cyclic initiator 3-ethylrhodanine.

[0298] The composition according to Example 8 contains lower amounts of catalyst (C) than the other examples according to the invention. Curing of the composition is also possible with these contents. The cured composition according to Example 8 exhibits a high elongation at break of 16%. The compositions according to Examples 9 and 10 contain increased amounts of the cyclic thioether (A) compared to the other examples according to the invention. In this variant, the tensile strength and the modulus of elasticity are increased.

[0299] Example 11 contains a high proportion of a monofunctional thietane in addition to the difunctional thiirane. The curable mass exhibits an induction period of 29.6 min and a comparatively low reaction enthalpy of -108 J / g.

[0300] The compositions according to Examples 12 to 24 each contain a radically curable compound (D) and a photoinitiator (E1). Example 12 shows a light-curable variant with a purely difunctional proportion of thioether compound (A). The composition according to Example 14 also contains a thermal initiator (E2). The composition according to Example 15 contains increased amounts of catalyst (C). The compositions are also solvent-free.

[0301] The composition according to Example 16 contains rhodanine as the cyclic initiator (B). The composition according to Example 17 contains a linear initiator (B). Both compositions achieve good tensile strengths. The curing time of the formulation according to Example 17 is significantly increased.

[0302] The composition according to Example 18 contains cyclic thioethers (A) and an epoxy component. The use of epoxides as additive (F) alongside cyclic thioethers can accelerate curing while simultaneously lowering temperatures. However, the complete replacement of component (A) with epoxides is not within the scope of the invention. A corresponding Comparative Example 26 shows that such compositions are not curable within the scope of the invention.

[0303] The compositions of Examples 19 and 20 additionally contain an adhesion promoter. The composition according to Example 19 also contains further additives (F), so that this composition has a total proportion of additives (F) of 66 percent by weight, based on the total weight of the composition. The reaction enthalpy of this composition is -58 J / g. Thus, with the compositions according to the invention, it is possible to formulate even highly filled systems that can be handled safely and still enable excellent curing behavior and high tensile strengths. The composition according to Example 21 contains smaller amounts of the cyclic thioether (A) while maintaining consistently good mechanical properties. An increased proportion of monofunctional cyclic thioether, as in the composition according to Example 22, does result in a reduction in tensile strength, but this is still sufficiently high.

[0304] The composition according to Example 23 shows the combination of linear and cyclic initiator (B), which can also be used according to the invention.

[0305] Example 24 uses a hybrid functional component. By combining an acrylate and a thiirane function, the polymer networks formed by light fixation and heat curing can be linked, resulting in cured masses with advantageous properties. The cured mass exhibits a high tensile strength of 48.3 MPa.

[0306] In Comparative Example 25, the use of a catalyst (C) was omitted.

[0307] In Comparative Example 26, the thioether compound (A) was replaced by a difunctional glycidyl ether based on bisphenol A. Comparative Example 27 does not contain difunctional thiirane (A1).

[0308] All masses of the comparative examples are not curable within the meaning of the invention.

[0309] The inventive combination of at least one thioether compound (A) with an initiator (B) and a catalyst (C) allows the formulation of compositions with a sharply defined temperature range for heat curing and an induction period. This is evident from the measurement data shown in Figs. 1 and 2.

[0310] Fig. 1 shows the DSC curve of the curable composition of Example 1 according to the invention. Curing occurs within a sharply defined temperature range with an onset at 101 °C. The peak temperature is 107 °C, and the determined reaction enthalpy is -182 J / g.

[0311] Fig. 2 shows an isothermal measurement of the curable composition of Example 1 according to the invention, carried out at a temperature of 80 °C. During an induction period of 10.6 minutes, no measurable curing occurs. The composition then rapidly cures over a curing time of 4.3 minutes.

Claims

Patent claims 1. A curable mass which is liquid at room temperature and comprises a) at least one thioether compound (A), wherein the at least one thioether compound (A) comprises an at least difunctional cyclic thioether, b) at least one initiator (B), and c) at least one catalyst (C).

2. Composition according to claim 1, characterized in that the thioether compound (A) comprises one or more at least difunctional thiiranes (A1) and / or one or more at least difunctional thietanes (A2).

3. Composition according to claim 2, characterized in that the thioether compound (A) comprises a mixture of one or more at least difunctional thiiranes (A1) and one or more monofunctional thiiranes (A1).

4. A composition according to any one of the preceding claims, characterized in that the initiator (B) contains a (thio)carbonylthio group.

5. Composition according to claim 4, characterized in that the initiator (B) is 2,4-thiazolidinedione or an oligomeric thioether compound (B4) prepared therefrom.

6. A composition according to any one of the preceding claims, characterized in that the thioether compound (A) is present in the curable composition in a ratio of 5 to 300 equivalents relative to one equivalent of the initiator (B).

7. Composition according to one of the preceding claims, characterized in that the catalyst (C) is selected from the group of quaternary ammonium salts, quaternary phosphonium salts, tertiary sulfonium salts and / or secondary iodonium salts.

8. A composition according to any one of the preceding claims, characterized in that the catalyst (C) is present in a ratio of 0.005 to 5 equivalents, based on one equivalent of the initiator (B), is contained in the curable mass.

9. A composition according to any one of the preceding claims, wherein the composition further contains a radically curable compound (D) and / or an initiator for radical polymerization (E).

10. Mass according to one of the preceding claims, characterized in that the mass comprises the following components: 15 to 99 percent by weight of at least one thioether compound (A), 0.1 to 20 percent by weight of the initiator (B), 0.01 to 10% by weight of the catalyst (C), 0 to 50 percent by weight of a radically curable compound (D), and 0 to 5 percent by weight of an initiator (E) for activating the radical polymerization, in each case based on the total mass of components (A) to (E), the proportions of components (A) to (E) adding up to 100 percent by weight.

11. Mass according to claim 10, characterized in that the mass comprises up to 85% by weight of additives (F), based on the total weight of the mass with all components.

12. Use of the composition according to one of the preceding claims for joining, casting and / or coating substrates.

13. Use according to claim 12, wherein the substrate is an electronic or optoelectronic component.

14. A method for producing a component using a curable mass according to one of claims 1 to 11, comprising the following steps: a) dosing the mass onto a first substrate; b) optionally feeding a second substrate to form a substrate composite comprising the first substrate and the second substrate, wherein the second substrate is brought into contact with the mass metered onto the first substrate; c) optionally irradiating the mass with actinic radiation to achieve a fixing strength sufficient for further processing of the first substrate or the substrate composite; and d) heating the optionally irradiated mass on the first substrate or in the substrate composite to a predetermined curing temperature which leads to curing to form the component, wherein the component comprises the first substrate and a cured adhesive layer which is bonded to the first substrate and optionally to the second substrate.

15. The method according to claim 14, wherein the heating in step d) takes place below the onset temperature of the mass at an induction temperature, wherein the induction temperature is in particular at most 30 °C below the onset temperature.

16. The method according to claim 15, wherein the heat source for heating the mass is removed after a predetermined pre-activation time and the mass hardens after a predetermined waiting time without use of the heat source.

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