COMPOSITION FOR SILICON RUBBER MATERIALS

Description

[0001] The invention relates to a curable composition comprising a polyorganosiloxane, a crosslinker with suitable exit groups and a heterocyclic azasilane, as well as a method for producing the curable composition and its use as a sealant, adhesive, coating agent, jointing material, potting compound, adhesive and in paints.

[0002] Silicone rubber compounds are materials with elastic properties and a wide range of applications, especially in plumbing and building construction. They can be used as sealants, jointing compounds, coatings, potting compounds, and adhesives for various materials such as glass, porcelain, ceramics, stone, plastics, metals, wood, etc. Cold-curing silicone rubber compounds, also known as room temperature curing (RTV) silicone rubber compounds, are frequently used, particularly one-component RTV silicone rubber compounds (RTV-1). These silicone rubber compounds are typically plastically deformable mixtures of polyorganosiloxanes with crosslinkable functional groups and suitable crosslinking agents (hardeners), which are stored in a dry environment. These mixtures crosslink under the influence of water or atmospheric humidity at room temperature. This process is called curing.Additionally, adhesion promoters are regularly used in silicone rubber compounds. In silicone rubber compounds (e.g., sealants or adhesives), they ensure good adhesion to various substrates.

[0003] Cold-curing silicone rubber compounds typically employ polyorganosiloxanes (silicones) bearing two or more crosslinkable functional groups, along with polyfunctional hardeners. α,ω-Dihydroxypolyorganosiloxanes are of particular importance as difunctional polyorganosiloxanes. The crosslinking agents or hardeners often possess hydrolyzable SiX groups, releasing leaving groups upon hydrolysis. These leaving groups allow the hardeners to be classified as acidic, neutral, or basic. Well-known leaving groups include carboxylic acids, alcohols, and oximes.

[0004] The curing, crosslinking, or polymerization of RTV-1 silicone rubber compounds can be further accelerated by the addition of suitable catalysts. Tin compounds have proven to be advantageous catalysts in this regard, as they exhibit high catalytic activity.

[0005] German patent DE 10 2015 204 787 A1 describes curable silicone rubber compounds containing at least one polyorganosiloxane having at least one hydroxyl group bonded to the silicon atom, at least one silane, one aminosilane, and a tin compound as a catalyst. However, tin compounds have the disadvantage of being toxic, especially the commonly used alkyltin compounds. Furthermore, their storage stability and adhesion to a wide range of substrates still require improvement.

[0006] EP 3 392 313 A1 describes curable silicone rubber compounds containing a silicone compound with two terminal hydroxyl groups, a catalyst containing a metal-siloxane-silanol(ate) compound, and a crosslinker comprising a silane with corresponding leaving groups. The catalyst can also be tin-free. However, storage stability and adhesion to various substrates still require improvement.

[0007] EP 3 613 803 A1 describes a composition for silicone rubber compounds, wherein the composition comprises a hardener in the form of a silane with corresponding exit groups and at least one heterocyclic organosilane.

[0008] The compositions described above are RTV-1 silicone rubber compounds that cure in the presence of humidity at room temperature; however, the storage stability of these compositions and their adhesion to various substrates still require improvement.

[0009] Document US 2021 / 324195 A1 discloses compositions that include a hydroxy-terminated polysiloxane, an ethyl lactatosilane crosslinker, a catalyst, some additives and also an azasilane BDC.

[0010] The object of the invention is therefore to overcome these disadvantages and to provide a silicone rubber-based composition that cures at room temperature, has high storage stability and exhibits good adhesion to all common materials or substrates.

[0011] This problem is solved by the composition specified in claim 1, the method specified in claim 14, and the uses specified in claim 15. Advantageous embodiments are found, inter alia, in the dependent claims and are explained in more detail below.

[0012] In one embodiment, the composition according to the invention comprises (a) a polyorganosiloxane of the formula HO-(SiR<l<R<m<O)<o)o-H, wherein each R<l< and R<m< independently represents an optionally substituted alkyl, alkenyl, or alkynyl group; an optionally substituted cycloaliphatic, aryl, or aralkyl group; or an optionally substituted heteroalicyclic or heteroaryl group; and o is an integer from 5 to 5000, (b) a crosslinker of the formula Si(R)m(Ra)4-m, wherein each R independently represents an optionally substituted alkyl, alkenyl, or alkynyl group; an optionally substituted cycloaliphatic, aryl, or aralkyl group; or an optionally substituted heteroalicyclic or heteroaryl group; where m is an integer from 0 to 2, each R a< is independently selected from the group consisting of (b1) a hydroxycarboxylic acid ester residue of formula (I): wherein each R<b< and R<c< independently represents hydrogen; an optionally substituted alkyl, alkenyl, or alkynyl group; an optionally substituted cycloaliphatic group, aryl group, or aralkyl group; or an optionally substituted heteroalicyclic group or heteroaryl group; each R<d< independently represents an optionally substituted alkyl, alkenyl, or alkynyl group; an optionally substituted cycloaliphatic group, aryl group, or aralkyl group; or an optionally substituted heteroalicyclic group or heteroaryl group; each R< independently represents carbon; an optionally substituted cycloaliphatic group, aryl group, or aralkyl group; or an optionally substituted heteroalicyclic group or heteroaryl group; and n is an integer from 1 to 10, (b2) a hydroxycarboxylic acid amide group having the formula (II): where each R< n< , R< o< , R< p< and R< q< independently represents hydrogen; an optionally substituted alkyl, alkenyl or alkynyl group; an optionally substituted cycloaliphatic group, aryl group or aralkyl group; or an optionally substituted heteroalicyclic group or heteroaryl group; R< independently represents carbon; an optionally substituted cycloaliphatic group, aryl group or aralkyl group; or an optionally substituted heteroalicyclic group or heteroaryl group; and p is an integer from 1 to 10, (b3) a carboxylic acid residue -OC(O)-R f< , (b4) an oxime residue -ON=CR g< R h< , and (b5) a carboxylic acid amide residue -N(R i< )-C(O)-R j< , wherein each R f< , R g< , R h< , R i< and R j< independently represents hydrogen; an optionally substituted alkyl, alkenyl or alkynyl residue; an optionally substituted cycloaliphatic residue, aryl residue or aralkyl residue;or an optionally substituted heteroalicyclic or heteroaryl group; (c) a heterocyclic azasilane, wherein N and Si are ring atoms and are directly linked together; and (d) an organophosphonic acid of the formula R-PO(OH)₂, wherein R represents an optionally substituted alkyl, alkenyl, or alkynyl group, an optionally substituted cycloaliphatic group, aryl group, or aralkyl group, or an optionally substituted heteroalicyclic or heteroaryl group.

[0013] Surprisingly, this composition exhibits improved storage stability and improved adhesion to various plastics, without negatively affecting other essential properties of thermosetting compositions, in particular the through-curing, tack-free time, complete curing, transparent appearance, Shore A hardness, and adhesion to various other substrates.

[0014] The heterocyclic azasilane in the curable composition according to the invention has the advantage over conventional aminosilanes in corresponding silicone rubber compounds that it only undergoes ring opening in the presence of atmospheric moisture, i.e., only during crosslinking of the curable composition, thus yielding the reactive aminosilane. In this way, reactions of aminosilanes with the crosslinker and other components of the curable composition are avoided before they are exposed to atmospheric moisture. This increases storage stability. Surprisingly, it was found that the combination of a heterocyclic azasilane and an organophosphonic acid, in particular an alkylphosphonic acid, leads to a further significant improvement in storage stability.Surprisingly, this is particularly the case when using crosslinkers containing, for example, hydroxycarboxylic acid ester residues or hydroxycarboxylic acid amide residues, and it is especially relevant for these crosslinkers because they contain reactive leaving groups (especially more reactive than alkoxysilanes, which contain alkoxy groups as leaving groups) and such crosslinkers generally lead to low storage stability due to the reactive leaving groups.

[0015] For the purposes of this invention, "crosslinkers" or "hardeners" are understood to mean, in particular, crosslinkable silane compounds that have at least two groups that can be cleaved by hydrolysis. Examples of such crosslinkable silane compounds are Si(OCH3)4, Si(CH3)(OCH3)3, and Si(CH3)(C2H5)(OCH3)2. Crosslinkers can also be referred to as hardeners. "Crosslinker" also includes, in particular, "crosslinker systems" that may contain more than one crosslinkable silane compound.

[0016] "Sealants", "sealing materials" or "sealing compounds" refer to elastic substances applied in liquid to viscous form or as flexible profiles or sheets for sealing a surface, especially against water, gases or other media.

[0017] The term "adhesive" refers to substances that join components through surface adhesion and / or internal strength (cohesion). This term includes, in particular, glues, pastes, dispersion adhesives, solvent-based adhesives, reactive adhesives, and contact adhesives.

[0018] "Coating agents" are all agents used to coat a surface.

[0019] In the context of the invention, "potting compounds" or "cable potting compounds" are compounds that can be processed hot or cold for potting cables and / or cable accessories.

[0020] The term "alkyl group" refers to a saturated hydrocarbon residue. Alkyl groups typically have the formula -CnH2n+1. The term "C1 to C16 alkyl group" specifically denotes a saturated hydrocarbon chain with 1 to 16 carbon atoms. Examples of alkyl groups include methyl, ethyl, propyl, butyl, isopropyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, and ethylhexyl. Alkyl groups can also be substituted, even if this is not explicitly stated.

[0021] "Straight-chain alkyl groups" refer to alkyl groups that do not contain any branches. Examples of straight-chain alkyl groups are methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl.

[0022] "Branched alkyl groups" refer to alkyl groups that are not straight-chain, meaning that the hydrocarbon chain, in particular, has a fork. Examples of branched alkyl groups are isopropyl, isobutyl, sec-butyl, tert-butyl, sec-pentyl, 3-pentyl, 2-methylbutyl, isopentyl, 3-methylbut-2-yl, 2-methylbut-2-yl, neopentyl, ethylhexyl, and 2-ethylhexyl.

[0023] The term "alkenyl groups" refers to hydrocarbon residues containing at least one double bond. For example, an alkenyl group with one double bond has the formula -CnH2n-1. However, alkenyl groups can also have more than one double bond. The term "C2- to C16-alkenyl group" specifically refers to a hydrocarbon chain with 2 to 16 carbon atoms. The number of hydrogen atoms varies depending on the number of double bonds in the alkenyl group. Examples of alkenyl groups are vinyl, allyl, 2-butenyl, and 2-hexenyl.

[0024] "Straight-chain alkenyl groups" refer to alkenyl groups that contain no branches. Examples of straight-chain alkenyl groups are vinyl, allyl, n-2-butenyl, and n-2-hexenyl.

[0025] "Branched alkenyl groups" are alkenyl groups that are not straight-chain, meaning that the hydrocarbon chain, in particular, has a branching structure. Examples of branched alkenyl groups are 2-methyl-2-propenyl, 2-methyl-2-butenyl, and 2-ethyl-2-pentenyl.

[0026] The term "alkynyl groups" refers to hydrocarbon residues containing at least one triple bond. For example, an alkynyl group with a triple bond has the formula -CnH2n-3. Alkynyl groups can also contain more than one triple bond. Furthermore, they can contain double and triple bonds. Examples include ethynyl, propynyl, butynyl, and pentynyl. Alkynyl groups can be substituted or unsubstituted.

[0027] The term "aryl groups" refers to mono- or polycyclic aromatic residues. "Aromatic" denotes cyclic, planar hydrocarbons with a conjugated aromatic π-electron system. Aryl groups include, for example, monocyclic (e.g., phenyl), bicyclic (e.g., indenyl, naphthalenyl, tetrahydronapthyl, or tetrahydroindenyl), and tricyclic (e.g., fluorenyl, tetrahydrofluorenyl, anthracenyl, or tetrahydroanthracenyl) ring systems in which the monocyclic ring system or at least one of the rings in a bicyclic or tricyclic ring system is aromatic. Specifically, a C4 to C14 aryl group refers to an aryl group containing 4 to 14 carbon atoms. Aryl groups can also be substituted, even if this is not explicitly stated.

[0028] An aromatic group can be monocyclic, bicyclic, tricyclic, or polycyclic. Furthermore, an aromatic group can also consist of 1 to 5 heteroatoms selected from the group consisting of N. , They contain oxygen and sulfur. These groups are also called heteroaryl groups (see below). Examples of aromatic groups are benzene, naphthalene, anthracene, phenanthrene, furan, pyrrole, thiophene, isoxazole, pyridine, and quinoline, where in each of the above examples the necessary number of hydrogen atoms have been removed to allow inclusion in the corresponding structural formula.

[0029] A "cycloalkyl group" or "cycloaliphatic residue" refers to a mono- or polycyclic hydrocarbon residue that is non-aromatic. Specifically, a cycloalkyl group with 4 to 14 carbon atoms refers to a non-aromatic hydrocarbon ring with 4 to 14 carbon atoms. Cycloalkyl groups can be saturated or partially unsaturated. Saturated cycloalkyl groups are non-aromatic and do not contain any double or triple bonds. Partially unsaturated cycloalkyl groups, unlike saturated cycloalkyl groups, contain at least one double or triple bond, but are not aromatic. Cycloalkyl groups can also be substituted, even if this is not explicitly stated.

[0030] An "aralkyl group" refers to an alkyl group substituted by an aryl group. A "C5 to C15 aralkyl group" specifically refers to an aralkyl group with 5 to 15 carbon atoms, containing the carbon atoms of both the alkyl and aryl groups. Examples of aralkyl groups are benzylethyl and phenylethyl. Aralkyl groups can also be substituted, even if this is not explicitly stated.

[0031] A "cyclic ring system" refers to a non-aromatic hydrocarbon ring. In particular, a cyclic ring system with 4 to 14 carbon atoms refers to a non-aromatic hydrocarbon ring system with 4 to 14 carbon atoms. A cyclic ring system can consist of a single hydrocarbon ring (monocyclic), two hydrocarbon rings (bicyclic), or three hydrocarbon rings (tricyclic). In particular, cyclic ring systems can also contain 1 to 5 heteroatoms, preferably selected from the group consisting of N, O, and S.

[0032] "Saturated cyclic ring systems" are non-aromatic and do not contain double or triple bonds. Examples of saturated cyclic ring systems are cyclopentane, cyclohexane, decalin, norbornane, and 4H-pyran, where in each of these examples the necessary number of hydrogen atoms have been removed to allow inclusion in the corresponding structural formula. For example, in a structural formula HO-R*-CH3, where R* is a cyclic ring system with six carbon atoms, specifically cyclohexane, two hydrogen atoms would be removed from the cyclic ring system, particularly from cyclohexane, to allow inclusion in the structural formula.

[0033] A "heteroaryl" group, as used herein, denotes a monocyclic or polycyclic aromatic ring, in particular consisting of 5 to 10 ring atoms, where one, two, three, or four ring atoms are nitrogen, oxygen, or sulfur, and the remainder is carbon. Heteroaryl groups can be substituted or unsubstituted. If they are substituted, the substituents are defined as above for cycloalkyl.

[0034] A "heteroalicyclic residue" or "heterocycloalkyl group," as used herein, denotes a monocyclic or fused ring of 5 to 10 ring atoms containing one, two, or three heteroatoms selected from N, O, and S, with the remainder of the ring atoms being carbon. A "heterocycloalkenyl" group additionally contains one or more double bonds. However, the ring does not have a complete conjugated π-electron system. If substituted, the substituents are defined as above for cycloalkyl.

[0035] Unless otherwise specified, N denotes nitrogen. Furthermore, O denotes oxygen, unless otherwise specified. S denotes sulfur and Si denotes silicon, unless otherwise specified.

[0036] "Optionally substituted" means that hydrogen atoms in the corresponding group or residue may be replaced by substituents. Substituents may be selected, in particular, from the group consisting of C1 to C4 alkyl, methyl, ethyl, propyl, butyl, phenyl, benzyl, halogen, fluorine, chloro, bromo, iodine, hydroxy, amino, alkylamino, dialkylamino, C1 to C4 alkoxy, phenoxy, benzyloxy, cyano, nitro, and thio compounds. When a group is described as optionally substituted, 0 to 50, in particular 0 to 20, hydrogen atoms in the group may be replaced by substituents. When a group is substituted, at least one hydrogen atom is replaced by a substituent.

[0037] "Alkoxy" refers to an alkyl group that is linked to the main carbon chain via an oxygen atom.

[0038] For the purposes of the invention, a heterocyclic azasilane is understood to be a cyclic organic compound containing a silicon atom and a nitrogen atom, each as ring atoms. These can be rings with 3 to 12 members, preferably 5 or 6 members, and particularly preferably 5 members. In the heterocyclic azasilane of the invention, the silicon and nitrogen atoms are directly linked. Such cyclic or heterocyclic azasilanes are also referred to as heterocyclic aminosilanes, although they are not actually aminosilanes, because the corresponding aminosilanes are only formed from the heterocyclic azasilanes with neighboring silicon and nitrogen atoms through ring opening upon reaction with water.

[0039] The term "polysiloxane" or "polyorganosiloxane" refers to an organosilicon compound. A polyorganosiloxane contained in the composition is an α,ω-dihydroxyl-terminated polyorganosiloxane. In addition to homopolymeric α,ω-dihydroxyl-terminated polydiorganosiloxanes, heteropolymeric α,ω-dihydroxyl-terminated polydiorganosiloxanes with different organic substituents can also be used. This includes both copolymers of monomers with identical organic substituents on a silicon atom and copolymers of monomers with different organic substituents on a silicon atom, e.g., those with mixed alkyl, alkenyl, and / or aryl substituents. The preferred organic substituents include straight-chain and branched alkyl groups with 1 to 8 carbon atoms, in particular methyl, ethyl, n- and iso-propyl, and n-, sec- and tert-butyl, vinyl and phenyl.In these compounds, one or all of the carbon-bonded hydrogen atoms in the individual organic substituents can be substituted by common substituents, such as halogen atoms or functional groups like hydroxyl and / or amino groups. For example, α,ω-dihydroxyl-terminated polydiorganosiloxanes with partially fluorinated or perfluorinated organic substituents can be used, or α,ω-dihydroxyl-terminated polydiorganosiloxanes with organic substituents substituted by hydroxyl and / or amino groups on the silicon atoms can be used.

[0040] Preferred examples of organosilicon compounds are α,ω-dihydroxyl-terminated polydialkylsiloxanes, such as α,ω-dihydroxyl-terminated polydimethylsiloxanes, α,ω-dihydroxyl-terminated polydiethylsiloxanes, or α,ω-dihydroxyl-terminated polydivinylsiloxanes, as well as α,ω-dihydroxyl-terminated polydiarylsiloxanes, such as α,ω-dihydroxyl-terminated polydiphenylsiloxanes. Polyorganosiloxanes with a kinematic viscosity of 5,000 to 120,000 cSt (at 25°C) are preferred, particularly those with a viscosity of 20,000 to 100,000 cSt, and especially those with a viscosity of 40,000 to 90,000 cSt. Mixtures of polydiorganosiloxanes with different viscosities can also be used.

[0041] The term "sealant" or "sealing agent" as used herein describes a hardened composition according to the invention.

[0042] For the purposes of this invention, "silicone rubber compounds" are synthetic silicone-containing rubber compounds, which, within the scope of this invention, are also interchangeably referred to as curable silicone compositions. This includes rubber polymers, polycondensates, and polyadducts that can be converted into a highly elastic, cured state by crosslinking with suitable crosslinking agents. Furthermore, these are plastically formable mixtures, for example, of α,ω-dihydroxypolyorganosiloxanes and suitable hardeners or crosslinking agents, which can be stored in the absence of moisture, but which polymerize under the influence of water or atmospheric humidity at room temperature.

[0043] The term "catalyst" refers to a substance that lowers the activation energy of a particular reaction and thereby increases the reaction rate.

[0044] The composition can contain the compound with the formula HO-(SiR l< R m< O) o -H and the crosslinker with the formula Si(R) m (R a< ) 4-m in the form of a prepolymer. The prepolymer is a reaction product of the two components. These reactions are known and are also referred to as endcapping, as described, for example, in WO 2016 / 146648 A1.

[0045] Tensile strength is one of the mechanical properties of polymers that can be determined using various testing methods. Tensile strength can be determined by measuring the tensile stress at the moment the test specimen breaks during a tensile test.

[0046] The "elongation at break" is the ratio of the change in length to the original length after the fracture of the test specimen. It expresses a material's ability to withstand deformation without cracking. Elongation at break is determined in a tensile test according to DIN EN ISO 8339 and DIN 53504.

[0047] The "tensile stress value" defines the stress exerted on the bonding surfaces or the adjacent building material when the sealant is stretched to 100%.

[0048] The "secant modulus" describes the ratio of stress to strain at any point on the curve of a stress-strain diagram. It is the slope of a curve from its starting point to any point on the stress-strain curve.

[0049] The "resilience" describes the tendency of a flexible beam to fully or partially return to its original dimensions after the forces that caused the expansion or deformation have been removed. The average resilience is determined according to DIN EN ISO 7389.

[0050] In a preferred embodiment of the invention, the curable composition comprises (a) at least one compound of the formula HO-(SiR l< R m< O) o -H, where R l< and R m< are defined as above and o is an integer from 5 to 5000, (b) at least one crosslinker of the formula Si(R) m (R a< ) 4-m , where each R independently represents an optionally substituted, straight-chain or branched C1 to C16 alkyl group, an optionally substituted, straight-chain or branched C2 to C16 alkenyl group or an optionally substituted C4 to C14 aryl group, m is an integer from 0 to 2, and each R a< is independently selected from the group consisting of a hydroxycarboxylic ester residue of the formula (I): where each R< b< independently means H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group or an optionally substituted C4 to C14 aryl group, each R< c< independently means H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group or an optionally substituted C4 to C14 aryl group, R< d< means an optionally substituted, straight-chain or branched C1 to C16 alkyl group, an optionally substituted, straight-chain or branched C2 to C16 alkenyl or alkynyl group, an optionally substituted C4 to C14 cycloalkyl or cycloalkenyl group, an optionally substituted C5 to C15 aralkyl group or an optionally substituted C4 to C14 aryl group, R< e< C or an optional substituted saturated or partially unsaturated cyclic ring system with 4 to 14 carbon atoms or an optionally substituted aromatic group with 4 to 14 carbon atoms, means,and n is an integer from 1 to 10, a hydroxycarboxylic acid amide residue with the formula (II): , where each R< n< independently means H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group or an optionally substituted C4 to C14 aryl group, each R< o< independently means H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group or an optionally substituted C4 to C14 aryl group, R< p< and R< q< independently means H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group, an optionally substituted C4 to C14 cycloalkyl group, an optionally substituted C5 to C15 aralkyl group or an optionally substituted C4 to C14 aryl group, R< r< means C or an optionally substituted saturated or partially unsaturated cyclic ring system with 4 to 14 C atoms or an optionally substituted aromatic group with 4 to 14 C atoms, and p is an integer from 1 to 10, a carboxylic acid residue -OC(O)-R f< ,where Rf < H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group, an optionally substituted C4 to C14 cycloalkyl group, an optionally substituted C4 to C14 aryl group, or an optionally substituted C5 to C15 aralkyl group, represents an oxime residue -ON=CR<g < Rh, where Rg < and R<< independently represent H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group, an optionally substituted C4 to C14 cycloalkyl group, an optionally substituted C4 to C14 aryl group, or an optionally substituted C5 to C15 aralkyl group, and a carboxylic acid amide residue -N(Ri < )-C(O)-Rj, where Ri < H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group, an optionally substituted C4 to C14 cycloalkyl group or an optionally substituted C4 to C14 aryl group or an optionally substituted C5 to C15 aralkyl group,where Rj < H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group, an optionally substituted C4 to C14 cycloalkyl group, an optionally substituted C4 to C14 aryl group, or an optionally substituted C5 to C15 aralkyl group, (c) a heterocyclic azasilane, wherein N and Si are ring atoms and are directly linked together, and (d) an organophosphonic acid of the formula R-PO(OH)2, wherein R represents an optionally substituted alkyl, alkenyl, or alkynyl group, an optionally substituted cycloaliphatic group, aryl group, or aralkyl group, or an optionally substituted heteroalicyclic group or heteroaryl group.

[0051] The amount of organophosphonic acid, based on the total amount of crosslinking agent, is preferably 0.3 - 30 mol-%, particularly preferably 1 - 10 mol-%, further preferably 3 - 8 mol-% and most preferably 5 - 7 mol-%.

[0052] The molar ratio of crosslinker to organophosphonic acid is preferably 3–350, more preferably 5–120, and most preferably 10–20. The amount of organophosphonic acid, based on the total amount of heterocyclic azasilanes, is preferably 1–30 mol%, more preferably 3–25 mol%, and most preferably 8–18 mol%.

[0053] In the organophosphonic acid of the formula R-PO(OH) 2 , there is R preferably represents an optionally substituted alkyl, alkenyl or alkynyl group, each with 2 - 12 carbon atoms, an optionally substituted cycloaliphatic group, aryl group or aralkyl group, each with 6 - 12 carbon atoms, or an optionally substituted heteroalicyclic group or heteroaryl group, each with 6 - 12 carbon atoms.

[0054] The organophosphonic acid is further preferably an alkylphosphonic acid, wherein the alkyl group comprises 2 to 12 carbon atoms, preferably 4 to 10 carbon atoms, more preferably 6 to 9 carbon atoms, and most preferably 8 carbon atoms. The alkyl group can be substituted or unsubstituted, preferably unsubstituted, and / or it can be branched or unbranched, preferably unbranched. The organophosphonic acid is most preferably octylphosphonic acid, in particular n-octylphosphonic acid.

[0055] The compound of the formula HO-(SiR l< R m< O) o -H is a silicone compound, also known as polyorganosiloxane, wherein Each R< and R< independently represents an optionally substituted alkyl, alkenyl or alkynyl residue; an optionally substituted cycloaliphatic residue, aryl residue or aralkyl residue; or an optionally substituted heteroalicyclic residue or heteroaryl residue; and o is an integer from 5 to 5000.

[0056] In a preferred embodiment, each R< l< and R< independently represents an optionally substituted, straight-chain or branched C1 to C16 alkyl group, an optionally substituted, straight-chain or branched C2 to C16 alkenyl group, or an optionally substituted C4 to C14 aryl group.

[0057] In a further preferred embodiment, the polyorganosiloxane HO-(SiR l< R m< O) o -H o contains an integer from 5 to 3500, more preferably from 10 to 3500, even more preferably from 100 to 3000, in particular from 800 to 2000, most preferably from 1000 to 1800.

[0058] In another embodiment, the polyorganosiloxane HO-(SiR l< R m< O) o -H has a weight-average molecular weight M w of 400 to 5,000,000, in particular of 3,000 to 2,500,000, of 15,000 to 1,000,000, of 30,000 to 750,000, of 50,000 to 500,000 or of 110,000 to 150,000.

[0059] Furthermore, the composition concerns a polyorganosiloxane HO-(SiR l< R m< O) o -H, which has a kinematic viscosity of 20 to 500000 cSt at 25°C.

[0060] In a preferred embodiment, the polyorganosiloxane HO-(SiR l< R m< O) o -H has a kinematic viscosity of 20 to 350000 cSt or of 20000 to 100000 cSt or of 20000 to 90000 cSt or of 20000 to 80000 cSt at 25°C.

[0061] In a further preferred embodiment, the composition comprises polyorganosiloxane HO-(SiR l< R m< O) o -H, wherein R l< and R m< independently represent an optionally substituted, straight-chain or branched C1 to C16 alkyl group, in particular an optionally substituted, straight-chain or branched C1 to C12 or C1 to C8 alkyl group, an optionally substituted, straight-chain or branched C2 to C16 alkenyl group, in particular an optionally substituted, straight-chain or branched C2 to C12 or C2 to C8 alkenyl group, or an optionally substituted C4 to C14 aryl group, in particular an optionally substituted C4 to C10 aryl group.

[0062] In a particularly preferred embodiment, the composition according to the invention comprises a polyorganosiloxane HO-(SiR l< R m< O) o -H, wherein R l< and R m< are independently selected from the group consisting of methyl, ethyl, propyl, butyl, trifluoromethyl, vinyl, allyl, butenyl, phenyl and naphthyl.

[0063] In a particularly preferred embodiment, the composition according to the invention contains a polyorganosiloxane HO-(SiR l< R m< O) o -H, wherein the polyorganosiloxane is α,ω-dihydroxy-dimethyl-polysiloxane.

[0064] Furthermore, the composition according to the invention contains crosslinkers of the formula Si(R) m (Ra<) 4-m, wherein each Ra< is independently selected from the group consisting of: a hydroxycarboxylic acid ester residue with formula (I): a hydroxycarboxylic acid amide residue with formula (II): a carboxylic acid residue -OC(O)-R f< , an oxime residue -ON=CR g< R h< , a carboxylic acid amide residue -N(R i< )-C(O)-R j< ,

[0065] In a preferred embodiment, the crosslinker has residues R of the formula Si(R) m (R a< ) 4-m, wherein each residue R independently represents an optionally substituted, straight-chain or branched C1 to C12 alkyl group, in particular an optionally substituted, straight-chain or branched C1 to C8 alkyl group, or an optionally substituted, straight-chain or branched C2 to C12 alkenyl group, in particular an optionally substituted, straight-chain or branched C2 to C8 alkenyl group, or an optionally substituted C4 to C10 aryl group.

[0066] In a particularly preferred embodiment, each R residue of the crosslinker of formula Si(R) m (R a< ) 4-m is independently a methyl, ethyl, propyl, vinyl, phenyl or allyl residue.

[0067] In a preferred embodiment, the composition according to the invention comprises crosslinked elements of the formula Si(R) m (Ra<) 4-m, wherein each Ra< is independently selected from the group consisting of: a hydroxycarboxylic acid ester residue with formula (I): a hydroxycarboxylic acid amide residue with formula (II): a carboxylic acid residue -OC(O)-R f< , an oxime residue -ON=CR g< R h< , a carboxylic acid amide residue -N(R i< )-C(O)-R j< , where Each R< b< independently of each other means H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group or an optionally substituted C4 to C14 aryl group, means each R< c< independently of each other means H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group or an optionally substituted C4 to C14 aryl group, means R< d< an optionally substituted, straight-chain or branched C1 to C16 alkyl group, an optionally substituted, straight-chain or branched C2 to C16 alkenyl or alkynyl group, an optionally substituted C4 to C14 cycloalkyl or cycloalkenyl group, an optionally substituted C5 to C15 aralkyl group or an optionally substituted C4 to C14 aryl group, means R< e< C or an optional substituted saturated or partially unsaturated cyclic ring system with 4 to 14 carbon atoms or an optionally substituted aromatic group with 4 to 14 carbon atoms, means,and n is an integer from 1 to 10; where each R< n< independently means H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group or an optionally substituted C4 to C14 aryl group, means each R° independently means H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group or an optionally substituted C4 to C14 aryl group, means R< p< and R< q< independently means H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group, an optionally substituted C4 to C14 cycloalkyl group, an optionally substituted C5 to C15 aralkyl group or an optionally substituted C4 to C14 aryl group, means R< r< C or an optionally substituted saturated or partially unsaturated cyclic ring system with 4 to 14 C atoms or an optional substituted aromatic group with 4 to 14 carbon atoms, means,and p is an integer from 1 to 10; where R<f><H represents an optionally substituted, straight-chain or branched C1 to C16 alkyl group, an optionally substituted C4 to C14 cycloalkyl group, an optionally substituted C4 to C14 aryl group, or an optionally substituted C5 to C15 aralkyl group; where R<g><H and R<h><H independently represent H, an optionally substituted, straight-chain or branched C1 to C16 alkyl group, an optionally substituted C4 to C14 cycloalkyl group, an optionally substituted C4 to C14 aryl group, or an optionally substituted C5 to C15 aralkyl group; and where R<i<H or an optionally substituted, straight-chain or branched C1 to C16 alkyl group, an optionally substituted C4 to C14 cycloalkyl group, or an optionally substituted C4 to C14 aryl group, or an optionally substituted C5 to C15 aralkyl group, and R<j<H or an optionally substituted,straight-chain or branched C1 to C16 alkyl group, an optionally substituted C4 to C14 cycloalkyl group, an optionally substituted C4 to C14 aryl group, or an optionally substituted C5 to C15 aralkyl group.

[0068] In a preferred embodiment of the invention, the crosslinker has residues R, wherein each R independently represents an optionally substituted, straight-chain or branched C1 to C12 alkyl group, in particular an optionally substituted, straight-chain or branched C1 to C8 alkyl group, or an optionally substituted, straight-chain or branched C2 to C12 alkenyl group, in particular an optionally substituted, straight-chain or branched C2 to C8 alkenyl group, or an optionally substituted C4 to C10 aryl group.

[0069] In a particularly preferred embodiment, each R group of the crosslinker of formula Si(R)m (Ra<)4m is independently a methyl, ethyl, propyl, vinyl, phenyl, or allyl group. In the hydroxycarboxylic acid ester group of the crosslinker, each R<b< and R<c< is preferably independently an optionally substituted, straight-chain or branched C1 to C12 alkyl group, in particular an optionally substituted, straight-chain or branched C1 to C8 alkyl group. The number n is preferably an integer from 1 to 5, in particular from 1 to 3, and n = 1 is particularly preferred.

[0070] In a preferred embodiment of the invention, in the hydroxycarboxylic acid ester residue of the crosslinker, each R<b and R< is selected independently of each other from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, n-butyl, sec-butyl, iso-butyl and tert-butyl, in particular from the group consisting of H and methyl.

[0071] In the hydroxycarboxylic acid ester residue of the crosslinker, R< d< is preferably an optionally substituted, straight-chain or branched C1 to C12 alkyl group, in particular an optionally substituted, straight-chain or branched C1 to C8 alkyl group, an optionally substituted, straight-chain or branched C2 to C12 alkenyl or alkynyl group, in particular an optionally substituted, straight-chain or branched C2 to C18 alkenyl group, a C4 to C10 cycloalkyl group, a C5 to C11 aralkyl group or a C4 to C10 aryl group.

[0072] In a further preferred embodiment of the invention, the hydroxycarboxylic acid ester residue of the crosslinker R< is selected from the group consisting of phenyl, tolyl, naphthyl, benzyl, cyclohexyl, methyl, ethyl, propyl, isopropyl, butyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, pentyl, n-pentyl, sec-pentyl, 3-pentyl, 2-methylbutyl, iso-pentyl, 3-methylbut-2-yl, 2-methylbut-2-yl, neopentyl, hexyl, heptyl, octyl, ethylhexyl, 2-ethylhexyl, and vinyl. Methyl, ethyl, and vinyl are particularly preferred.

[0073] In a preferred embodiment, the hydroxycarboxylic acid ester residue of the crosslinker R e< is a divalent benzene residue or R e< C and R b< and R c< H or R e< C and R b< H and R c< Methyl-.

[0074] In a particularly preferred embodiment, R< a< of the crosslinking agent is a hydroxycarboxylic acid residue and n is an integer from 1 to 5, particularly preferably n = 1 to 3, in particular 1. Particularly preferred is the crosslinking agent methyl tris(ethyl lactato)silane and / or tetra(ethyl lactato)silane.

[0075] In one embodiment, in the composition according to the invention, each R< n< and R< in the hydroxycarboxylic acid amide residue of the crosslinker is independently H or an optionally substituted, straight-chain or branched C1 to C12 alkyl group, in particular an optionally substituted, straight-chain or branched C1 to C8 alkyl group.

[0076] In the hydroxycarboxylic acid amide residue of the crosslinker, each R n< and R o< is preferably selected independently of each other from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, n-butyl, sec-butyl, iso-butyl and tert-butyl, in particular from the group consisting of H and methyl.

[0077] In a further embodiment, the hydroxycarboxylic acid amide residue of the crosslinker R p< and R q< independently includes H or an optionally substituted, straight-chain or branched C1 to C12 alkyl group, in particular an optionally substituted, straight-chain or branched C1 to C8 alkyl group, or an optionally substituted C4 to C14 cycloalkyl group or a C5 to C11 aralkyl group or a C4 to C10 aryl group.

[0078] In a preferred embodiment, the hydroxycarboxylic acid amide residue R< p< and R< of the crosslinker are independently selected from the group consisting of H, phenyl-, tolyl-, naphthyl-, benzyl-, cyclohexyl-, methyl-, ethyl-, propyl-, isopropyl-, butyl-, n-butyl-, sec-butyl-, iso-butyl-, tert-butyl-, pentyl-, n-pentyl-, sec-pentyl-, 3-pentyl-, 2-methylbutyl-, iso-pentyl-, 3-methylbut-2-yl-, 2-methylbut-2-yl-, neopentyl-, hexyl-, heptyl-, octyl-, ethylhexyl-, and 2-ethylhexyl-.

[0079] In one embodiment, the hydroxycarboxylic acid amide residue of the crosslinker R r< contains a divalent benzene residue or R r< C and R n< and R o< H or R r< C and R n< H and R o< Methyl-.

[0080] In a further preferred embodiment, the hydroxycarboxylic acid amide residue p of the crosslinker contains an integer number from 1 to 5, in particular from 1 to 3, with p = 1 being particularly preferred.

[0081] In the carboxylic acid residue of the crosslinker of the composition according to the invention, R f< is preferably H or an optionally substituted, straight-chain or branched C1 to C12 alkyl group, an optionally substituted C4 to C10 cycloalkyl group or an optionally substituted C4 to C10 aryl group or an optionally substituted C5 to C11 aralkyl group, in particular H or an optionally substituted, straight-chain or branched C1 to C8 alkyl group, an optionally substituted C4 to C8 cycloalkyl group or an optionally substituted C4 to C10 aryl group or an optionally substituted C5 to C11 aralkyl group.

[0082] In a preferred embodiment, the carboxylic acid residue of the crosslinker R< is selected from the group consisting of H ,Phenyl-, tolyl-, naphthyl-, benzyl-, cyclohexyl-, methyl-, ethyl-, propyl-, isopropyl-, butyl-, n-butyl-, sec-butyl-, iso-butyl-, tert-butyl-, pentyl-, n-pentyl-, sec-pentyl-, 3-pentyl-, 2-methylbutyl-, iso-pentyl-, 3-methylbut-2-yl-, 2-methylbut-2-yl-, neopentyl-, hexyl-, heptyl-, octyl-, ethylhexyl-, and 2-ethylhexyl-. In a particularly preferred embodiment, the crosslinking agent is ethyltriacetoxysilane and / or methyltriacetoxysilane and / or propyltriacetoxysilane.

[0083] In a further preferred embodiment, the oxime residue of the crosslinker according to the invention contains, independently of one another, H or an optionally substituted, straight-chain or branched C1 to C12 alkyl group, an optionally substituted C4 to C10 cycloalkyl group or an optionally substituted C4 to C10 aryl group or an optionally substituted C5 to C11 aralkyl group, in particular H or an optionally substituted, straight-chain or branched C1 to C8 alkyl group, an optionally substituted C4 to C8 cycloalkyl group or an optionally substituted C4 to C10 aryl group or an optionally substituted C5 to C11 aralkyl group.

[0084] In a preferred embodiment, the oxime residue R<g< and R< of the crosslinker are independently selected from the group consisting of H, phenyl-, tolyl-, naphthyl-, benzyl-, cyclohexyl-, methyl-, ethyl-, propyl-, isopropyl-, butyl-, n-butyl-, sec-butyl-, iso-butyl-, tert-butyl-, pentyl-, n-pentyl-, sec-pentyl-, 3-pentyl-, 2-methylbutyl-, iso-pentyl-, 3-methylbut-2-yl-, 2-methylbut-2-yl-, neopentyl-, hexyl-, heptyl-, octyl-, ethylhexyl-, and 2-ethylhexyl-. In a particularly preferred embodiment, the crosslinking agent with oxime residue is methyl tris(2-pentanon oximo)silane, vinyl tris(2-pentanon oximo)silane and / or tetra(2-pentanon oximo)silane.

[0085] In a further preferred embodiment of the invention, in the carboxylic acid amide residue of the crosslinker according to the invention R i< and R j<, H or an optionally substituted, straight-chain or branched C1 to C12 alkyl group, an optionally substituted C4 to C10 cycloalkyl group or an optionally substituted C4 to C10 aryl group or an optionally substituted C5 to C11 aralkyl group, in particular H or an optionally substituted, straight-chain or branched C1 to C8 alkyl group, an optionally substituted C4 to C8 cycloalkyl group or an optionally substituted C4 to C10 aryl group or an optionally substituted C5 to C11 aralkyl group.

[0086] In the carboxylic acid amide residue of the crosslinker, R and R are preferably selected independently of one another from the group consisting of H, phenyl, tolyl, naphthyl, benzyl, cyclohexyl, methyl, ethyl, propyl, isopropyl, butyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, pentyl, n-pentyl, sec-pentyl, 3-pentyl, 2-methylbutyl, iso-pentyl, 3-methylbut-2-yl, 2-methylbut-2-yl, neopentyl, hexyl, heptyl, octyl, ethylhexyl, and 2-ethylhexyl. In a particularly preferred embodiment, the crosslinker with carboxylic acid amide residue is methylethoxybis(N-methylbenzamido)silane.

[0087] In a further particularly preferred embodiment, mixtures of the described crosslinkers are used for the curable compositions according to the invention. In a further particularly preferred embodiment, the crosslinker carries various residues R a< as described above.

[0088] Furthermore, the composition according to the invention contains a heterocyclic azasilane, which can function, among other things, as an adhesion promoter in the composition. A mixture of several heterocyclic azasilanes can also be used.

[0089] In a preferred embodiment, the heterocyclic azasilane is a compound of the formula where a = 0, 1 or 2; n = 0 - 6; Each RK< , RL< , RM< , RO< , RP< and RQ< independently signifies H or an optionally substituted, straight-chain or branched C1 to C20 alkyl group, an optionally substituted, straight-chain or branched C2 to C20 alkenyl group, an optionally substituted C3 to C20 cycloalkyl group, an optionally substituted C4 to C20 cycloalkenyl group, an optionally substituted, straight-chain, branched or cyclic C4 to C20 alkynyl group or an optionally substituted, straight-chain or branched C2 to C20 heteroalkyl group, an optionally substituted, straight-chain, branched or cyclic C3 to C20 heteroalkenyl group or an optionally substituted C4 to C14 aryl or heteroaryl group or two residues RK< , RL< , RM< , RO< , RP< and RQ< together form a 5- to 8-membered ring.

[0090] The parameter a in (RP< ) a and (OR Q< ) 2-a represents a ratio of alkoxy residues OR Q< to residues RP< as defined herein. Here, a can take values ​​from 0 to 2. If a = 0, the corresponding heterocyclic organosilane contains no residue RP< and two OR Q< residues. The parameter a can also be 1. In this case, one RP< residue and one OR Q< residue are directly bonded to the silicon atom of the heterocyclic organosilane. If a = 2, only RP< residues and no OR Q< residues are bonded to the silicon atom.

[0091] The substituents (RM< ) n in formula (III) are directly related to the ring size, which is determined by the parameter n. The possible number of substituents on the ring atoms is also adjusted by the value of n. For example, if a 6-membered ring is present, n = 2, and the number of substituents R c< or RC< is adjusted accordingly to 2. Thus, each ring atom can carry one substituent.

[0092] The heterocyclic azasilane can carry different substituents on each ring atom; each RK<, RL<, RM<, RO<, RP<, and RQ< from formula (III) is independently H or an optionally substituted, straight-chain or branched C1-to-C20 alkyl group, an optionally substituted, straight-chain or branched C2-to-C20 alkenyl group, an optionally substituted C3-to-C20 cycloalkyl group, an optionally substituted C4-to-C20 cycloalkenyl group, an optionally substituted, straight-chain, branched, or cyclic C4-to-C20 alkynyl group, an optionally substituted, straight-chain or branched C2-to-C20 heteroalkyl group, an optionally substituted, straight-chain, branched, or cyclic C3-to-C20 heteroalkenyl group, or an optionally substituted C4-to C14 aryl or heteroaryl group.Preferably, each RK< , RL< , RM< , RO< , RP< and RQ< independently represents H, or an optionally substituted straight-chain or branched C1-to-C10 alkyl group, an optionally substituted straight-chain or branched C2-to-C10 alkenyl group, an optionally substituted straight-chain or branched C2-to-C10 heteroalkyl group, an optionally substituted C3-to-C10 cycloalkyl group, or an optionally substituted C4-to-C8 aryl or heteroaryl group. Particularly preferred is each RK< , RL< , RM< , RO< , RP< and RQ< independently of each other H, an optionally substituted straight-chain or branched C1 to C8 alkyl group, an optionally substituted straight-chain or branched C2 to C8 alkenyl group, an optionally substituted straight-chain or branched C4 to C8 heteroalkyl group, an optionally substituted C4 to C6 cycloalkyl group or an optionally substituted C5 to C6 aryl or heteroaryl group.

[0093] n is preferably 1 - 4, more preferably 1 - 2, in particular 1.

[0094] In a preferred embodiment of the invention, the heterocyclic azasilane has the following structural formula:

[0095] The composition according to the invention may contain one or more of the compounds shown above (heterocyclic azasilanes).

[0096] Particularly preferred heterocyclic azasilanes are substituted or unsubstituted, especially unsubstituted, Nn-butyl-1-aza-2,2-dimethoxy-2-silacyclopentane ((BDC), CAS No. 618914-44-6), 2,2-diethoxy-1-(3-triethoxysilyl-propyl)aza-2-silacyclopentane ((TESPDC), CAS No. 1184179-50-7) and / or 2,2-diethoxy-1-(trimethylsilyl)aza-2-silacyclopentane ((TMS)DEC), CAS No. 21297-72-3)

[0097] In a preferred embodiment, the composition according to the invention contains the heterocyclic azasilane in an amount, based on the total weight of the composition, of 0.1 - 3 wt.%, preferably 0.2 - 2 wt.%, particularly preferably 0.3 - 1.5 wt.%.

[0098] The composition according to the invention preferably additionally contains a metal catalyst to accelerate the curing of the composition according to the invention. Particularly preferably, the composition according to the invention contains a metal catalyst that does not contain tin. These catalysts have the advantage that toxic tin is avoided. They solve the problem of the invention of avoiding toxic components of the composition, in particular toxic tin. Surprisingly, it was found within the scope of the invention that a curable composition with the advantages of increased storage stability through the combination of the heterocyclic azasilane and organophosphonic acid contained therein, in the presence of polyorganosiloxane and crosslinker, can also be provided with tin-free catalysts in the mixture, and rapid crosslinking still occurs, even though tin-containing catalysts are particularly effective catalysts in these silicone rubber compounds.In this way, the advantages of increased storage stability could be combined with the low toxicity of tin-free catalysts, while retaining the other beneficial properties of the hardenable compositions.

[0099] Preferably, the metal of the metal catalyst is selected from the group consisting of Na, Zn, Sc, Nd, Ti, Zr, Hf, V, Fe, Pt, Cu, Ga, and Bi, particularly preferably selected from the group consisting of Zn, Ti, Zr, Hf, V, Fe, and Bi. Most preferably, the metal of the metal catalyst is Zr.

[0100] In a preferred embodiment of the invention, the composition comprises a metal siloxane as a metal catalyst, in particular a metal siloxane of the formula R* A Si BOCMD, wherein each R* is independently selected from the group consisting of optionally substituted C1- to C20-alkyl, optionally substituted C3- to C6-cycloalkyl, optionally substituted C2- to C20-alkenyl, optionally substituted C6- to C10-aryl, -OH and -O-(C1- to C20-alkyl), wherein M is the metal, A is an integer from 4 to 19, B is an integer from 4 to 10, C is an integer from 8 to 30, and D is an integer from 1 to 8.

[0101] The metal siloxane is preferably a metal silsesquioxane, in particular a polyhedral metal silsesquioxane. A polyhedral metal silsesquioxane is understood to be a metal silsesquioxane in which silicon and metal atoms at least partially occupy the vertices of a polyhedron, for example, a cube.

[0102] Particularly preferred is the metal silsesquioxane a polyhedral titanium and / or zirconium silsesquioxane, especially a zirconium silsesquioxane.

[0103] In a preferred embodiment, the metal siloxane, preferably the metal silsesquioxane, has the following formula (IV) wherein X 1< , X 2< and X 3< are independently selected from Si or M 1< , wherein M 1< is a metal, preferably not tin, in particular selected from the group consisting of Na, Zn, Sc, Nd, Ti, Zr, Hf, V, Fe, Pt, Cu, Ga and Bi; particularly preferably from the group consisting of Zn, Ti, Zr, Hf, V, Fe and Bi, Z 1< , Z 2< and Z 3< are independently selected from the group consisting of L 2< , R 5< , R 6< and R 7< , wherein L 2< is selected from the group consisting of -OH and -O-(C1- to C10-alkyl), in particular -O-(C1- to C8-alkyl) or -O-(C1- to C6-alkyl), or wherein L 2< is selected from the group consisting of -OH, -O-methyl, -O-ethyl, -O-propyl, -O-butyl, -O-octyl, -O-isopropyl, and -O-isobutyl; R1<, R2<, R3<, R4<, R5<, R6< and R7< are independently selected from the group consisting of optionally substituted C1 to C20 alkyl, optionally substituted C3 to C8 cycloalkyl,optionally substituted C2- to C20-alkenyl and optionally substituted C5- to C10-aryl; Y1< and Y2< independently mean -OM2< -L3< Δ, or Y1< and Y2< together mean -OM2< (L3< Δ)-O- or -O-, wherein L3< is selected from the group consisting of -OH and -O-(C1- to C10-alkyl), in particular -O-(C1- to C8-alkyl) or -O-(C1- to C6-alkyl), or wherein L3< is selected from the group consisting of -OH, -O-methyl, -O-ethyl, -O-propyl, -O-butyl, -O-octyl, -O-isopropyl, and -O-isobutyl, and wherein M2< is a metal, preferably not tin, further preferably a metal selected from the group consisting of Na, Zn, Sc, Nd, Ti, Zr, Hf, V, Fe, Pt, Cu, Ga and Bi; especially preferably from the group consisting of Zn, Ti, Zr, Hf, V, Fe, Bi, and X 4< -M 3< L 1< Δ or M 3< means and Q 1< and Q 2< each mean H or a single bond linked with M 3<,wherein L 1< is selected from the group consisting of -OH and -O-(C1- to C10-alkyl), in particular -O-(C1- to C8-alkyl) or -O-(C1- to C6-alkyl), or wherein L 1< is selected from the group consisting of -OH, -O-methyl, -O-ethyl, -O-propyl, -O-butyl, -O-octyl, -O-isopropyl, and -O-isobutyl, and wherein M 3< is a metal, preferably not tin, further preferably a metal selected from the group consisting of Na, Zn, Sc, Nd, Ti, Zr, Hf, V, Fe, Pt, Cu, Ga and Bi; particularly preferably from the group consisting of Zn, Ti, Zr, Hf, V, Fe, Bi, or X 4< -M 3< L 1< means and Q 2< H or a single bond linked to M 3< means and Q 1< H, M 4< L 4< Δ or -SiR 8< means, wherein M 4< is a metal, preferably not tin, further preferably a metal selected from the group consisting of Na, Zn, Sc, Nd, Ti, Zr, Hf, V, Fe, Pt, Cu, Ga and Bi; particularly preferably from the group consisting of Zn, Ti, Zr, Hf, V, Fe and Bi,and wherein L 4< is selected from the group consisting of -OH and -O-(C1- to C10-alkyl), in particular -O-(C1- to C8-alkyl) or -O-(C1- to C6-alkyl), or wherein L 4< is selected from the group consisting of -OH, -O-methyl, -O-ethyl, -O-propyl, -O-butyl, -O-octyl, -O-isopropyl, and -O-isobutyl, and wherein R 8< is selected from the group consisting of optionally substituted C1- to C20-alkyl, optionally substituted C3- to C6-cycloalkyl, optionally substituted C2- to C20-alkenyl and optionally substituted C6- to C10-aryl, or where X 4< , Q 1< and Q 2< independently denote -M 3< L 1< Δ, or X 4< -Si(R 8< )-OM 3< L 1< Δ means Q 2< is a single bond linked to the Si atom of X 4< and Q 1< -M 4< L 4< Δ means, or X 4< -Si(R 8< )-OM 3< L 1< Δ means Q 2< is a single bond linked to the Si atom of X 4< and Q 1< is a single bond linked to the M 3< atom of X 4<. ,

[0104] In a particularly preferred embodiment, the metal silsesquioxane has the structural formula (V) wherein X 1< , X 2< and X 3< are independently selected from Si or M 1< , wherein M 1< is a metal, preferably not tin, further preferably a metal selected from the group consisting of Na, Zn, Sc, Nd, Ti, Zr, Hf, V, Fe, Pt, Cu, Ga and Bi; particularly preferably from the group consisting of Zn, Ti, Zr, Hf, V, Fe and Bi, Z 1< , Z 2< and Z 3< are independently selected from the group consisting of L 2< , R 5< , R 6< and R 7< , wherein L 2< is selected from the group consisting of -OH and -O-(C1- to C10-alkyl), in particular -O-(C1- to C8-alkyl) or -O-(C1- to C6-alkyl), or wherein L 2< is selected from the group consisting of -OH, -O-methyl, -O-ethyl, -O-propyl, -O-butyl, -O-octyl, -O-isopropyl, and -O-isobutyl;R 1< , R 2< , R 3< , R 4< , R 5< , R 6< and R 7< are independently selected from the group consisting of optionally substituted C1- to C20-alkyl, optionally substituted C3- to C8-cycloalkyl, optionally substituted C2- to C20-alkenyl and optionally substituted C5- to C10-aryl; where X 4< -M 3< L 1< Δ, where L 1< is selected from the group consisting of -OH and -O-(C1- to C10-alkyl), in particular -O-(C1- to C8-alkyl) or -O-(C1- to C6-alkyl), or where L 1< is selected from the group consisting of -OH, -O-methyl, -O-ethyl, -O-propyl, -O-butyl, -O-octyl, -O-isopropyl, and -O-isobutyl, and where M 3< is a metal, preferably not tin, more preferably a metal selected from the group consisting of Na, Zn, Sc, Nd, Ti, Zr, Hf, V, Fe, Pt, Cu, Ga and Bi; in particular preferably from the group consisting of Zn, Ti, Zr, Hf, V, Fe and Bi.

[0105] In a further particularly preferred embodiment, the metal silsesquioxane has the formula (VI). where X 4< -M 3< L 1< Δ, where L 1< is selected from the group consisting of -OH and -O-(C1- to C10-alkyl), in particular -O-(C1- to C8-alkyl) or -O-(C1- to C6-alkyl), or where L 1< is selected from the group consisting of -OH, -O-methyl, -O-ethyl, -O-propyl, -O-butyl, -O-octyl, -O-isopropyl, and -O-isobutyl, and where M 3< is a metal, preferably not tin, further preferably a metal selected from the group consisting of Na, Zn, Sc, Nd, Ti, Zr, Hf, V, Fe, Pt, Cu, Ga and Bi; particularly preferably from the group consisting of Zn, Ti, Zr, Hf, V, Fe and Bi, Z 1< , Z 2< and Z 3< are independently selected from the group consisting of optionally substituted C1- to C20-alkyl, optionally substituted C3- to C8-cycloalkyl, optionally substituted C2- to C20-alkenyl and optionally substituted C5- to C10-aryl;R1<, R2<, R3< and R4< are each independently selected from the group consisting of optionally substituted C1- to C20-alkyl, optionally substituted C3- to C8-cycloalkyl, optionally substituted C2- to C20-alkenyl and optionally substituted C5- to C10-aryl.

[0106] Particularly preferred in the above formulas is X 4< = ZrOR or TiOR, in particular ZrOR, with R = C1- to C12-alkyl, in particular ZrO-methyl, ZR-O-ethyl, ZR-O-propyl, ZR-O-butyl, ZR-O-octyl, ZR-O-isopropyl, ZR-O-isobutyl, ZR-O-butyl.

[0107] In a particularly preferred embodiment, the metal silsesquioxane has the structure (VII) where Zr is linked to OR, where R is selected from the group consisting of -H, -methyl, -ethyl, -propyl, -butyl, -octyl, -isopropyl, and -isobutyl, Z1<, Z2<, and Z3< each independently denote C1- to C20-alkyl, C3- to C8-cycloalkyl, C2- to C20-alkenyl, and C5- to C10-aryl, in particular are selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl, heptyl, octyl, vinyl, allyl, butenyl, and phenyl, and benzyl, and R1<, R2<, R3<, and R4< each independently denote C1- to C20-alkyl, C3- to C8-cycloalkyl, C2- to C20-alkenyl, and C5- to C10-aryl means, in particular selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl, heptyl, octyl, vinyl, allyl, butenyl and phenyl, and benzyl.

[0108] The weight ratio of the polyorganosiloxane (a), in particular the α, ω-dihydroxyl-terminated polydialkylsiloxane, to the crosslinker is preferably 100:1 - 2:1, particularly preferably 50:1 to 5:1, in particular 15:1 - 6:1.

[0109] The composition according to the invention may optionally contain further components beyond those described, in particular common additives such as fillers, plasticizers, reactive diluents, colorants, thixotropic agents, rheological additives, wetting agents, UV stabilizers, antioxidants, desiccants, etc. Preferably, the curable compositions according to the invention contain at least one further component.

[0110] The composition according to the invention may preferably contain plasticizers. End-group-capped polyethylene glycols, e.g., polyethylene or polypropylene glycol dialkyl ethers, wherein the alkyl group comprises one to four carbon atoms, are preferred as plasticizers, in particular dimethyl and diethyl ethers of diethylene glycol and dipropylene glycol. Diurethanes, which can be produced, for example, by reacting diols with OH end groups with monofunctional isocyanates, are also preferred as plasticizers. In a preferred embodiment of the invention, polyalkylsiloxanes, particularly preferably polydimethylsiloxane, are used as plasticizers.

[0111] The hardenable compositions preferably contain plasticizers in an amount of 2 to 50 wt.%, more preferably in an amount of 10 to 40 wt.%, and particularly preferably in an amount of 20 to 35 wt.%, in each case based on the total weight of the composition. If a mixture of several plasticizers is used, the quantities refer to the total amount of plasticizer in the composition.

[0112] If the viscosity of the curable composition needs to be reduced, reactive diluents can be added. Suitable reactive diluents are compounds that are miscible with the composition and possess at least one group that reacts with the polymer. Preferably, the reactive diluent has at least one functional group that reacts with moisture or atmospheric oxygen. Examples include isocyanate groups, silyl groups, or unsaturated groups such as vinyl groups. To produce preferred reactive diluents, for example, appropriate polyol components can be reacted with at least a difunctional isocyanate.

[0113] The composition according to the invention may further contain fillers. Suitable examples include chalk, lime flour, precipitated and / or pyrogenic silica, zeolites, bentonites, magnesium carbonate, alumina, tallow, titanium dioxide, iron oxide, zinc oxide, quartz, sand, mica, and other powdered or ground minerals. Organic fillers may also be used, in particular wood fibers, wood flour, sawdust, cellulose, cotton, and chaff.

[0114] In a particularly preferred embodiment of the invention, silica is added to the composition as a filler, in untreated and / or treated, preferably hydrophobized form, particularly preferably pyrogenic silicon dioxide, also referred to as pyrogenic silica. In a particularly preferred embodiment of the invention, a mixture of untreated and hydrophobized silica is added to the curable composition as a filler.

[0115] The fillers are preferably used in an amount of 1 to 60 wt.%, particularly preferably 2 to 20 wt.%, and most preferably 5 to 15 wt.%, in each case based on the total weight of the composition. Mixtures of several fillers can also be used. In this case, the quantities refer to the total amount of filler in the composition.

[0116] For some applications, additives or fillers that impart thixotropy to the preparations are preferred. Such fillers are also described as rheological aids, e.g., hydrogenated castor oil, fatty acid amides, or swellable polymers.

[0117] The composition according to the invention can contain additional adhesion promoters beyond the heterocyclic azasilane. Suitable adhesion promoters include, for example, resins such as aliphatic or petrochemical resins and modified phenolic resins, as well as terpene oligomers. Such resins are used, for example, as adhesion promoters for pressure-sensitive adhesives and coating materials. Terpene-phenolic resins are also suitable.

[0118] Preferably, the curable composition contains at least one stabilizer selected from the group consisting of antioxidants, UV stabilizers, and drying agents. Antioxidants are preferably present up to about 6% by weight, and particularly up to about 4% by weight. Within the scope of the present invention, it is preferred to use a UV stabilizer that contains a silyl group and is polymerized into the product during crosslinking or curing.

[0119] The composition according to the invention can also be stabilized against penetrating moisture by means of a desiccant in order to further increase its shelf life. Suitable desiccants include all compounds that react with water to form a group inert to the reactive groups present in the preparation. Isocyanates and silanes, such as vinylsilanes like 3-vinylpropyltriethoxysilane, oximosilanes, or carbamatosilanes, are suitable examples of desiccants. Methyl, ethyl, or vinyltrimethoxysilane, as well as tetramethyl or ethylethoxysilane, can also be used. Vinyltrimethoxysilane and tetraethoxysilane are particularly preferred.

[0120] In a preferred embodiment of the invention, the components of the composition are mixed together, in particular in the form of a single-phase mixture.

[0121] The invention also relates to a method for producing the curable composition according to the invention, wherein the components (a) to (d), and optionally further components, are mixed together.

[0122] The invention further relates to the use of the curable composition according to the invention, in particular as a sealant, adhesive, coating material, jointing compound, potting compound, adhesive and / or in paints.

[0123] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the present invention. The advantages of features or combinations of several features mentioned are merely examples and can have an effect alternatively or cumulatively. The combination of features from different embodiments of the invention or features from different claims is possible, deviating from the chosen cross-references in the claims.

[0124] The following examples serve to further illustrate the invention without limiting the invention thereto. Examples Example 1:

[0125] A silicone rubber compound is produced according to the following formulation: 570g alpha-omega hydroxyl-terminated polydimethylsiloxane with viscosity 80,000 cSt 270g polydimethylsiloxane with viscosity 100 cSt 50g untreated highly dispersed silica 50g hydrophobized highly dispersed silica Mixture of 40.7g methyl tris(ethyllactato)silane and 8.7g tetraethyllactatosilane 12.0g adhesion promoter butyldimethoxycyclosilane (BDC, Nn-butyl-1-aza-2,2-di-methoxy-2-silacyclopentane) 0.5g catalyst iBu-POSS-Zr-OEt 1.5g octylphosphonic acid

[0126] The sealant, after exposure to air, exhibits the following properties: a skin formation time of 5 min, a tack-free time of 35 min, early use after 180 min, complete curing after 24 h, a transparent appearance, a Shore A hardness of 18, good adhesion to wood, varnished wood, stained wood, aluminum, powder-coated aluminum, glass, PVC, polyamide, steel, concrete, etc.

[0127] The sealant is also characterized by its excellent storage stability. After 8 weeks of storage at 50°C in the cartridge, the sealant still exhibits the same properties as upon initial application. Example 2:

[0128] A silicone rubber compound is produced according to the following formulation: 570g alpha-omega hydroxyl-terminated polydimethylsiloxane with a viscosity of 80,000 cSt. 270g polydimethylsiloxane with viscosity 100 cSt, 50g untreated highly dispersed silica, 50g hydrophobized highly dispersed silica, 49.4g methyl tris(ethyl lactato)silane, 12.0g adhesion promoter butyldimethoxycyclosilane (BDC, Nn-butyl-1-aza-2,2-di-methoxy-2-silacyclopentane), 1.0g catalyst iBu-POSS-Zr-OEt, 1.5g octylphosphonic acid

[0129] The sealant, after exposure to air, exhibits the following properties: a skin formation time of 11 min, an tack-free time of 65 min, early use after 280 min, complete curing after 24 h, a transparent appearance, a Shore A hardness of 17, good adhesion to wood, varnished wood, stained wood, aluminum, powder-coated aluminum, glass, PVC, polyamide, steel, concrete, etc.

[0130] The sealant is also characterized by its excellent storage stability.

[0131] After 8 weeks of storage at 50°C in the cartridge, the sealant still has the same properties as when first applied.

[0132] For detailed investigation and comparison with an established silicone sealant, the following example 3 and the comparison example were examined in detail. Example 3

[0133] Analogous to Examples 1 and 2, a silicone rubber compound was produced according to the following formulation: Material % by weight 1 Polymer 80,000 cSt (α-ω-dihydroxy-dimethyl-polysiloxane) 57,1 2 Plasticizer 100 cSt (polydimethylsiloxane) 26,45 3 Crosslinker 1: (Methyl-tris(ethyllactato)silane) 3,6 4 Crosslinker 2: (Tetra(ethyllactato)silane) 1,4 5 Pyrogenic silica, hydrophobic (BET surface area 130 - 150 m² / g) 5,0 6 Pyrogenic silica, untreated (BET surface area 130 - 150 m² / g) 5,0 7 Adhesion promoter: BnDC (Benzyldimethoxycyclosilane, N-Benzyl-1-aza-2,2-dimethoxy-2-silacyclopentane) 1,2 8 Catalyst: iBu-POSS-Zr-OEt 0,1 9 Stabilizer octylphosphonic acid 0,15 Comparative example (state of the art)

[0134] component % by weight 1 α,ω-Dihydroxydimethylpolysiloxane 80,000 cSt 52,1 2 Polydimethylsiloxane (PDMS) 100 cSt 32,9 3 Crosslinker 1: Vinyl-tris(ethyllactato)silane 2,5 4 Crosslinker 2: Methyl tris(ethyllactato)silane 2,5 5 Aminopropyltriethoxysilane (AMEO) 0,2 6 Pyrogenic silica, untreated BET surface area 130-150 m² / g 8,5 7 Catalyst 1:1 (w / w) mixture of dialkylzine oxide and tetraalkoxysilane 0,1 8 Adhesion promoter: Nn-Butyl-1-aza-2,2-di-methoxy-2-silacyclopentane (BDC)(BDC) 1,2

[0135] The optical properties of the compositions of Examples 1 to 3 and the comparison example were comparable upon application, as were the mechanical properties after curing. However, it was found that the silicone rubber mixtures of Examples 1 to 3 exhibited improved storage stability and adhesion compared to the comparison example. The composition of Examples 1 to 3 remained colorless after eight weeks of storage at 50 °C, whereas the composition of the comparison example was yellowish after eight weeks at 50 °C. Regarding adhesion, the composition of Examples 1 to 3 showed improved adhesion to Plexiglas, polycarbonate, and polystyrene compared to the comparison example. An additional advantage of the above examples according to the invention is that toxic tin could be omitted.

[0136] The above examples show, in comparison to the sealant of the above comparison example, that the mechanical properties of the compositions according to the invention are equally good compared to known silicone rubber compositions, and at the same time the storage stability and the adhesion to plastics such as Plexiglas, polycarbonate or polystyrene could be improved.

Claims

1. Curable composition comprising (a) a polyorganosiloxane of the formula HO-(SiRlRmO)o-H, wherein each Rl and Rm independently represents an optionally substituted alkyl, alkenyl or alkynyl residue; an optionally substituted cycloaliphatic residue, aryl residue or aralkyl residue; or an optionally substituted heteroalicyclic residue or heteroaryl residue; and o is an integer from 5 to 5000, (b) a crosslinker of the formula Si(R)m(Ra)4-m, wherein each R independently represents an optionally substituted alkyl, alkenyl or alkynyl residue; an optionally substituted cycloaliphatic residue, aryl residue or aralkyl residue; or an optionally substituted heteroalicyclic residue or heteroaryl residue; m is an integer from 0 to 2, each Ra is independently selected from the group consisting of (b1) a hydroxycarboxylic acid ester residue of the formula (I): wherein each Rb and Rc independently of each other represents hydrogen; an optionally substituted alkyl, alkenyl or alkynyl residue; an optionally substituted cycloaliphatic residue, aryl residue or aralkyl residue; or an optionally substituted heteroalicyclic residue or heteroaryl residue; each Rd independently represents an optionally substituted alkyl, alkenyl or alkynyl residue; an optionally substituted cycloaliphatic residue, aryl residue or aralkyl residue; or an optionally substituted heteroalicyclic residue or heteroaryl residue; each Re independently represents carbon; an optionally substituted cycloaliphatic residue, aryl residue or aralkyl residue; or an optionally substituted heteroalicyclic residue or heteroaryl residue; and n is an integer from 1 to 10, (b2) a hydroxycarboxamide residue of the formula (II): wherein each Rn, Ro, Rp and Rq independently of each other represents hydrogen; an optionally substituted alkyl, alkenyl or alkynyl residue; an optionally substituted cycloaliphatic residue, aryl residue or aralkyl residue; or an optionally substituted heteroalicyclic residue or heteroaryl residue; Rr independently of each other represents carbon; an optionally substituted cycloaliphatic residue, aryl residue or aralkyl residue; or an optionally substituted heteroalicyclic residue or heteroaryl residue; and p is an integer from 1 to 10, (b3) a carboxylic acid residue -O-C(O)-Rf, (b4) an oxime residue -O-N=CRgRh, and (b5) a carboxylic acid amide residue -N(Ri)-C(O)-Rj, wherein each Rf, Rg, Rh, Ri and Rj independently of each other represents hydrogen; an optionally substituted alkyl, alkenyl or alkynyl residue; an optionally substituted cycloaliphatic residue, aryl residue or aralkyl residue; or an optionally substituted heteroalicyclic residue or heteroaryl residue; (c) a heterocyclic azasilane, wherein N and Si are ring atoms and are directly linked to each other, and (d) an organophosphonic acid of the formula R-PO(OH)2, wherein R represents an optionally substituted alkyl, alkenyl or alkynyl residue, an optionally substituted cycloaliphatic residue, aryl residue or aralkyl residue, or an optionally substituted heteroalicyclic residue or heteroaryl residue.

2. Composition according to claim 1, characterized in that the amount of organophosphonic acid, based on the total amount of crosslinker, is 0.3 - 30 mol%, preferably 1 - 10 mol%.

3. Composition according to claim 1 or 2, characterized in that the organophosphonic acid is an alkylphosphonic acid having 2 to 12 carbon atoms, preferably octylphosphonic acid.

4. Composition according to any one of claims 1 to 3, characterized in that the composition additionally comprises a metal catalyst, preferably a metal catalyst which does not contain tin.

5. Composition according to claim 4, characterized in that the metal of the metal catalyst is selected from the group consisting of Na, Zn, Sc, Nd, Ti, Zr, Hf, V, Fe, Pt, Cu, Ga, and Bi, preferably selected from the group consisting of Zn, Ti, Zr, Hf, V, Fe and Bi.

6. Composition according to claim 4 or 5, characterized in that the metal of the metal catalyst is Zr.

7. Composition according to any one of claims 4 to 6, characterized in that the metal catalyst is a metal siloxane of the formula         R*ASiBOCMD, wherein each R* is independently selected from the group consisting of optionally substituted C1 to C20 alkyl, optionally substituted C3 to C6 cycloalkyl, optionally substituted C2 to C20 alkenyl, optionally substituted C6 to C10 aryl, -OH and -O-(C1 to C20 alkyl), M is the metal, A is an integer from 4 to 19, B is an integer from 4 to 10, C is an integer from 8 to 30, and D is an integer from 1 to 8.

8. Composition according to claim 7, characterized in that the metal siloxane is a polyhedral metal silsesquioxane, in particular a polyhedral titanium and / or zirconium silsesquioxane.

9. Composition according to any one of claims 1 to 8, characterized in that in the crosslinker each Ra is independently selected from the group consisting of (b1) a hydroxycarboxylic acid ester residue of formula (I) wherein the residues are as defined in claim 1, and (b2) a hydroxycarboxylic acid amide residue of formula (II) wherein the residues are as defined in claim 1.

10. Composition according to any one of claims 1 to 9, characterized in that in the crosslinker Ra is a hydroxycarboxylic acid ester residue of the formula (I), preferably with n = 1.

11. Composition according to any one of claims 1 to 10, characterized in that the heterocyclic azasilane is a compound of the formula wherein a = 0,1 or 2; n = 0 - 6; each RK, RL, RM, RO, RP and RQ is independently H or an optionally substituted straight-chain or branched C1 to C20 alkyl group, an optionally substituted straight-chain or branched C2 to C20 alkenyl group, an optionally substituted C3 to C20 cycloalkyl group, an optionally substituted C4 to C20 cycloalkenyl group, an optionally substituted straight-chain, branched or cyclic C4 to C20 alkynyl group or an optionally substituted, straight-chain or branched C2 to C20 heteroalkyl group, an optionally substituted, straight-chain, branched or cyclic C3 to C20 heteroalkenyl group or an optionally substituted C4 to C14 aryl or heteroaryl group, or two residues RK, RL, RM, RO, RP and RQ together form a 5- to 8-membered ring.

12. Composition according to any one of claims 1 to 11, characterized in that the heterocyclic azasilane is N-n-butyl-1-aza-2,2-dimethoxy-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)aza-2-silacyclopentane and / or 2,2-di-ethoxy-1-(trimethylsilyl)aza-2-silacyclopentane, preferably N-n-butyl-1-aza-2,2-dimethoxy-2-silacyclopentane.

13. Composition according to any one of claims 1 to 12, characterized in that the polyorganosiloxane is polydimethylsiloxane.

14. Method for preparing a curable composition according to any one of claims 1 to 13, characterized in that components (a) to (d) and optionally further components are mixed.

15. Use of a curable composition according to any one of claims 1 to 13 as a sealant, glue, coating agent, jointing material, potting compound, adhesive or in paints.