Moisture-curing rtv silicone composition with a high degree of tear propagation resistance and high storage stability

Abstract

The invention relates to a moisture-curing silicone composition, comprising at least one crosslinkable polydiorganyl siloxane with alkoxysilane terminal groups, at least one condensation catalyst, at least one crosslinking agent with alkoxysilane groups, at least one ground chalk, which makes up at least the main component of all of the contained fillers, and optionally additional contents. The invention is characterized in that the ground chalk has a particle size d50, determined according to the Standard ISO 13320:2009, of more than 0.6 µm and less than 2 µm. The composition is particularly suitable as a low-modulus sealant and has excellent tear propagation resistance and an excellent storage stability, in particular in the form of an RTV-1 formulation.

Description

[0001] MOISTURE-CURING RTV SILICONE COMPOSITION WITH HIGH TEAR STRENGTH AND STORAGE STABILITY

[0002] Description

[0003] Technical area

[0004] The invention relates to moisture-curing, condensation-curing silicone compositions, their use as elastic adhesives and sealants, and processes for jointing and bonding substrates.

[0005] State of the art

[0006] Silicones are well-known compounds that have long been used as adhesives or sealants. Such silicones can be designed as one- or two-component silicone compositions and typically contain a crosslinkable polydiorganylsiloxane, a crosslinker, and a catalyst as their main components. A distinction is made between cold-curing RTV silicones (RTV = room temperature curing or vulcanizing) and hot-curing HTV silicones (HTV = high-temperature curing or vulcanizing). One- and two-component RTV silicones are also referred to as RTV-1 silicones and RTV-2 silicones, respectively.

[0007] Moisture-curing, condensation-curing RTV silicones have been around for a long time. It is also known that such compositions can cure based on so-called neutral crosslinking. Traditionally, neutral-curing RTV-1 silicones release oxime compounds, whose odor is perceived as highly unpleasant. These compounds are less preferred for health protection reasons and are increasingly subject to legal restrictions. As an alternative to oxime-releasing compositions, neutral-curing RTV-1 silicones can also be formulated with polydiorganylsiloxanes containing alkoxysilane groups. The only decomposition products of the crosslinking process are alcohols, which are split off from the alkoxysilane groups, usually methanol or ethanol, whose odor and toxicological profile are significantly less problematic than with oximes.

[0008] The polydiorganylsiloxanes used in moisture-curing, condensation-curing silicones can be terminated with hydroxyl groups. However, this type of end group has been shown to limit the achievable properties and lead to major problems during the compounding process, especially in the case of RTV-1 silicones. Alternatively, the polydiorganylsiloxanes can be modified with alkyl idialkoxysilyl or trialkoxysilyl end groups. Such modified polymers have been known for a long time. Their preparation via condensation reaction is described, for example, in EP763557 or EP0559045, and their preparation via hydrosilylation reaction is described, for example, in US4898910.

[0009] For use as low-modulus sealants, for example, for sealing joints in sanitary facilities, one-component silicones, i.e., RTV-1 silicones, are often used. If these are formulated with polydiorganylsiloxanes with alkyldialkoxysilyl or trialkoxysilyl end groups and equipped with tin-based curing catalysts, the resulting compounds often cure with comparatively high modulus, which is not well suited for use as sealants. This problem can be partially addressed by using titanate-based curing catalysts instead of tin-based ones. However, titanate-catalyzed RTV-1 silicones containing polydiorganylsiloxanes with alkyldialkoxysilyl or trialkoxysilyl end groups often lack sufficient storage stability. These sealants can thicken due to undesirable reactions in the closed container or, in the worst case, fail to cure.

[0010] In addition, RTV silicones generally have the problem of insufficient tear resistance. This manifests itself, for example, in small cracks in the cured composition rapidly propagating under minimal force, resulting in the cured material subsequently tearing or tearing through piecemeal, either cohesively or adhesively. This is undesirable for any application, but can usually only be prevented to some extent through careful formulation work and optimization, which is usually only possible at the expense of reduced other properties such as the material's mechanical properties or higher manufacturing costs. EP0649879, for example, discloses silicone compositions containing a specific filler combination of precipitated silica surface-modified with hexamethyldisilazane and stearate-coated precipitated calcium carbonate, as well as a tin catalyst.By using these very specific fillers, the tear resistance of the silicone composition can be improved. The disadvantage of compositions according to EP0649879 is that these specific fillers are complex to produce and therefore expensive. Furthermore, precipitated chalks usually contain significant amounts of water due to the manufacturing process, which necessitates very complex drying, especially if they are to be used in RTV-1 silicones, as otherwise storage stability cannot be guaranteed.

[0011] EP2641934, as a further example, also discloses silicone compositions with improved tear resistance, this effect being achieved by a particular filler combination in conjunction with a particular catalyst combination.

[0012] The disadvantage of compositions as disclosed in EP2641934 is that these compositions have increased viscosities and are therefore difficult to apply manually or even pump and, moreover, have a potential to be harmful to the environment or health due to the mandatory use of several different organometallic catalysts.

[0013] WO2018033563, as another example, discloses silicone compositions with improved tear resistance, which is achieved in particular by combining two polydiorganosiloxane polymers of different reactivity in a specific molar ratio. A disadvantage of the solution of WO2018033563 is that formulation freedom is limited by the narrow selection of polymers, which is associated with limitations in the possible product properties and higher formulation costs. Therefore, there is a need for easily prepared, moisture-curing, condensation-curing silicone compositions based on polydiorganylsiloxanes with alkoxysilyl end groups, which are suitable as low-modulus sealants and exhibit excellent tear resistance and excellent storage stability, thus overcoming the disadvantages of the prior art.

[0014] EP1043356 discloses a one-component silicone composition containing a polyether siloxane and a finely divided chalk filler with a particle size of 4.5 μm or less. The compositions disclosed in this document have particularly low modulus and exhibit good adhesion properties. However, tear resistance was not investigated, and ground chalks are not preferred.

[0015] Description of the invention

[0016] The object of the present invention is therefore to provide a moisture-curing, condensation-curing RTV silicone composition based on polydiorganylsiloxanes with alkoxysilyl end groups, which has both excellent tear resistance and very good storage stability and which can be used as a one-component, low-modulus sealant.

[0017] It has surprisingly been found that using a ground chalk with a particle size of less than 2 pm as a filler in an RTV silicone composition based on alkoxysilane-terminated polydiorganosiloxane polymers can achieve an unexpectedly high improvement in tear propagation resistance, which is particularly surprising when using an organotin catalyst. Furthermore, in preferred embodiments, an unusually good storage stability can be achieved, especially when using titanate-based catalysts, which are typically particularly problematic with regard to storage stability.

[0018] Accordingly, the invention relates to a moisture-curing, condensation-crosslinking silicone composition comprising a) at least one crosslinkable polydiorganylsiloxane P having alkoxysilane end groups; b) at least one condensation catalyst K; c) at least one crosslinker V having alkoxysilane groups; d) at least one ground chalk GK, which makes up at least the majority of all fillers contained; e) optionally further ingredients, in particular an unreactive polydiorganylsiloxane as a plasticizer, characterized in that the ground chalk GK has a particle size d50, determined according to the standard ISO 13320:2009, of more than 0.6 pm and less than 2 pm.

[0019] The invention is explained in detail below.

[0020] Ways to implement the invention

[0021] The viscosities stated here can be determined according to DIN 53018. The measurement can be carried out using a cone-and-plate viscometer MCR101 from Anton-Paar, Austria, with a cone type CP 25-1 at 23°C. The stated viscosity values ​​refer to a shear rate of 0.5 s -1 .

[0022] The crosslinking reaction involves hydrolysis and condensation reactions of alkoxysilyl groups. These are known to those skilled in the art and can be schematically represented as follows.

[0023] =Si-OR + H2O =Si-OH + ROH (1)

[0024] =Si-OH + HO-Si= =Si-O-Si= + H2O (2) Upon the addition of water and optionally with the aid of a catalyst, alkoxysilyl groups hydrolyze to form silanols (Si-OH) and an alcohol (step 1). The silanols are generally unstable and condense spontaneously to form siloxane bonds (-Si-O-Si-), thus forming siloxanes (step 2). If more than one alkoxy group is present per Si atom, more highly condensed systems can be formed. In the case of partial hydrolysis, only a portion of the alkoxy groups is hydrolyzed and condensed. The reaction rate of the crosslinking reaction depends on the kinetics of the individual steps. These kinetics can, for example, be 1 H-NMR and 29 Si-NMR experiments for individual components, as described, for example, in “Zeitschrift für Naturforschung (1999), 54b, 155-164” and “Phosphorus, Sulfur, and Silicone and the Related Elements (2011), 186(2), 240-254”.

[0025] The term "homogeneous deep curing" used here refers to the homogeneous curing of a silicone composition in a joint across its entire cross-section. This means that the properties, particularly the mechanical properties such as hardness and elasticity, of the silicone composition after curing are identical on the front and back sides of the joint, within the respective measurement accuracies.

[0026] The composition according to the invention contains a) at least one crosslinkable polydiorganylsiloxane P with alkoxysilane end groups; b) at least one condensation catalyst K; c) at least one crosslinker V with alkoxysilane groups; d) at least one ground chalk GK, which constitutes at least the majority of all fillers present; e) optionally further ingredients, in particular an unreactive polydiorganylsiloxane as a plasticizer, characterized in that the ground chalk GK has a particle size d50, determined according to the ISO 13320:2009 standard, of more than 0.6 pm and less than 2 pm. The composition according to the invention is a moisture-curing, condensation-curing RTV silicone. This can be present as a one-component composition (RTV-1 silicone), in which all ingredients are mixed and the mixture is stored in the absence of moisture.Such RTV-1 silicones cure upon contact with water, generally through contact with atmospheric moisture. Alternatively, they can be present as a two-component composition (RTV-2). The composition according to the invention is preferably a one-component RTV-1 silicone composition.

[0027] Polydiorganylsiloxane P with alkoxysilane end groups

[0028] The composition according to the invention contains at least one crosslinkable polydiorganylsiloxane P with alkoxysilane end groups. Such crosslinkable polydiorganylsiloxanes are well known to those skilled in the art. The crosslinkable polydiorganylsiloxanes have functional groups, in particular two or more functional groups, via which crosslinking is possible. These functional groups can be present in a side group or an end group of the polydiorganylsiloxane, with terminal functional groups being preferred. Such polydiorganylsiloxanes with terminal functional groups are also referred to as α, α-functional polydiorganylsiloxanes. The functional groups of the at least one crosslinkable polydiorganylsiloxane P are alkoxy groups.

[0029] The viscosity of the polydiorganylsiloxanes P used can vary widely depending on the intended use. The polydiorganylsiloxane used according to the invention can, for example, have a viscosity of 10 to 500,000 mPa s, preferably 5,000 to 400,000 mPa s, particularly preferably 6,000 to 350,000 mPa s at a temperature of 23°C.

[0030] The crosslinkable polydiorganylsiloxane P is preferably a linear

[0031] Polydiorganylsiloxane, in particular a polydiorganylsiloxane of formula (I)

[0032] The residues R 1 , R 2 and R 3 independently of one another represent linear or branched, monovalent hydrocarbon radicals having 1 to 12 C atoms, which optionally contain one or more heteroatoms, and optionally one or more CC multiple bonds and / or optionally cycloaliphatic and / or aromatic moieties.

[0033] In particular, the residues R 1 and R 2 for alkyl radicals having 1 to 5, in particular 1 to 3, carbon atoms, preferably methyl groups. The radicals R 3 independently of one another represent in particular phenyl, vinyl or methyl groups.

[0034] The residues R 4 independently of one another represent alkoxy groups each having 1 to 13 C atoms, which may optionally contain one or more heteroatoms, and optionally one or more CC multiple bonds and / or optionally cycloaliphatic and / or aromatic moieties.

[0035] Y in formula (I) is a divalent hydrocarbon group having 1 to 8 C atoms, preferably having 2 to 6 C atoms, particularly preferably an ethylene or hexylene bridge, or an oxygen atom, or a group of the general formula (II)

[0036] ' OR 3 '

[0037] -Si-O- (II)

[0038] - OR 3 -I , where R 3has the meaning given above and 1 = 1-5.

[0039] The index m of the general formula (I) is chosen such that the polydiorganylsiloxane P has, for example, the above-mentioned viscosity at a temperature of 23 °C. The index m of the general formula (I) can, for example, be in the range from 10 to 10,000 and preferably from 100 to 1,500. The polydiorganylsiloxane P of formula (I) is, in particular, a polydiorganylsiloxane of formula (Ia). where R 1 , R 2 , R 3 , R 4 and m have the same meanings and the same preferred embodiments as indicated for the polydiorganylsiloxane P of formula (I).

[0040] The at least one crosslinkable polydiorganylsiloxane P is an alkoxy-terminated polydiorganylsiloxane, preferably a crosslinkable alkoxy-terminated polydimethylsiloxane. Preferably used crosslinkable polydiorganylsiloxanes are linear polydiorganylsiloxanes. Thus, radicals R4 in formula (I) or formula (Ia) independently of one another preferably represent alkoxy groups having 1 to 8 C atoms, which may optionally be substituted by F, N, P, O and / or S.

[0041] The residues R 3 in formula (I) or formula (Ia) can, for example, be independently selected from one or more of the groups methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, n-pentyl, i-pentyl, n-hexyl, i-hexyl, n-heptyl, i-heptyl, n-octyl, i-octyl, cyclopentyl, cyclohexyl, phenyl, vinyl, allyl, methoxymethyl, 2-methoxyethyl, ethoxymethyl, 2-(2-methoxyethoxy)ethyl, trifluoropropyl, 2-aminoethyl, 6-aminohexyl.

[0042] Preferred radicals are R 3 in formulas (I) and (Ia) are independently selected from alkyl groups having 1 to 6, in particular having 1 to 3, C atoms, such as propyl, ethyl and methyl, with ethyl and methyl being preferred and methyl being particularly preferred.

[0043] In a particular embodiment, all radicals R 3 in formulas (I) and (Ia) are identical and selected from alkyl groups having 1 to 6, in particular having 1 to 3, carbon atoms, such as propyl, ethyl, and methyl, with methyl and ethyl being preferred and methyl being particularly preferred. The polydiorganylsiloxanes of the general formula (I) and / or formula (Ia) preferably make up at least 90%, preferably at least 95%, particularly preferably at least 99% of the total mass of polydiorganylsiloxane P present in a composition according to the invention.

[0044] Suitable polydiorganosiloxanes, as represented by formula (I) and / or formula (Ia), are known and commercially available. The preparation of such polydiorganosiloxanes also takes place in a known manner, as described, for example, in EP0658588.

[0045] Polydiorganylsiloxanes of general formula (Ia) can be prepared by condensation reaction of OH-terminated polydiorganylsiloxanes with alkoxy-functional silanes or siloxanes. Preparation by condensation reaction can be carried out by processes as described, for example, in EP763557 or EP0559045. Alternatively, polydiorganylsiloxanes of general formula (I) can be prepared by hydrosilylation reaction of vinyl-terminated polydiorganylsiloxanes with Si-H functional alkoxysilanes or siloxanes, or of Si-H terminated polydiorganylsiloxanes with vinyl-functional alkoxysilanes or siloxanes. Preparation by hydrosilylation reaction can be carried out by processes as described, for example, in US4898910.

[0046] In a preferred embodiment, polydiorganylsiloxanes of the general formula (I) and formula (Ia) are prepared by condensation reaction of OH-terminated polydiorganylsiloxanes with alkoxy-functional silanes or siloxanes. In a particularly preferred embodiment, polydiorganylsiloxanes of the general formula (I) and formula (Ia) are prepared by condensation reaction of OH-terminated polydiorganylsiloxanes with alkoxy-functional silanes or siloxanes under catalysis by amidines or guanidines, optionally under co-catalysis of a metal catalyst. Suitable amidine and guanidine catalysts are described, for example, in WO 2016 / 207156 and WO 2015 / 193208.In preferred embodiments of the moisture-curing silicone composition, the crosslinkable polydiorganylsiloxane P is prepared in a condensation reaction from OH-terminated polydiorganylsiloxane and a tri- or tetraalkoxysilane, preferably a methyltrialkoxysilane or a vinyltrialkoxysilane.

[0047] In particularly preferred embodiments of the moisture-curing silicone composition, the reaction of the OH-terminated polydiorganylsiloxane with the tri- or tetraalkoxysilane is carried out in the presence of an amidine or guanidine catalyst.

[0048] The moisture-curing silicone composition preferably contains between 10 wt.% and 60 wt.%, in particular between 15 wt.% and 50 wt.%, preferably between 20 wt.% and 40 wt.% of polydiorganylsiloxane P, based on the total composition.

[0049] Crosslinker V with alkoxysilane groups

[0050] The composition according to the invention further comprises at least one crosslinker V containing alkoxysilane groups. Alkoxysilane groups are hydrolyzable groups that, optionally with prior hydrolysis and formation of a silanol group, can react with the functional groups of the polydiorganylsiloxane to form a siloxane bond. The reaction between the functional group of the polydiorganylsiloxane and the hydrolyzable group of the crosslinker preferably occurs via a condensation reaction, optionally following a hydrolysis reaction of at least one of the alkoxysilane groups involved. Byproducts such as water or alcohols are generally released in the process.

[0051] Crosslinkers V according to the invention with hydrolyzable radicals correspond in particular to the general formula (III)

[0052] R^nSiX4-n (HI) where R 5independently of one another is a non-hydrolyzable monovalent hydrocarbon radical having 1 to 18 C atoms, which is saturated or unsaturated and optionally has one or more functional groups containing the elements F, N, P, O and / or S, n is 0, 1, 2 or 3, preferably 0 or 1, X independently of one another is an OH group or a linear or branched alkoxy group having 1 to 8 C atoms, which may optionally be substituted by F, N, P, O and / or S and optionally has unsaturated and / or cycloaliphatic and / or aromatic moieties.

[0053] If X represents an alkoxy group, alkoxy groups X are independently alkoxy groups having 1 to 8 C atoms, which may optionally be substituted by F, N, P, O and / or S and may optionally contain unsaturated and / or cycloaliphatic and / or aromatic moieties. The alkoxy groups X can, for example, be independently selected from one or more of the groups methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, n-pentoxy, i-pentoxy, n-hexoxy, i-hexoxy, n-heptoxy, i-heptoxy, n-octoxy, i-octoxy, cyclopentoxy, cyclohexoxy, phenoxy, vinyloxy, allyloxy, methoxymethoxy, 2-methoxyethoxy, ethoxymethoxy, 2-(2-methoxyethoxy)ethoxy, trifluoropropoxy, 2-aminoethoxy, 6-aminohexoxy.

[0054] Preferably, the alkoxy groups X are independently selected from alkoxy groups having 1 to 6, in particular having 1 to 3, C atoms, such as propoxy, ethoxy and methoxy, with methoxy and ethoxy being preferred and methoxy being particularly preferred.

[0055] In a particular embodiment, all groups X are the same and are selected from alkoxy groups having 1 to 6, in particular 1 to 3, C atoms, such as propoxy, ethoxy and methoxy, with methoxy and ethoxy being preferred and methoxy being particularly preferred.

[0056] Examples of crosslinkers of the general formula (III) are methyltrimethoxysilane, dimethyldimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, i-butyltrimethoxysilane, octyltrimethoxysilane, hexadecyltrimethoxysilane, vinyltrimethoxysilane, vinyltris(2-methoxyethoxy)silane, vinyldimethoxymethylsilane, phenyltrimethoxysilane, Tetramethylorthosilicate, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 2-aminoethyl-3-aminopropyltrimethoxysilane, (Trimethoxysilyl)methyl-O-methylcarbamate, N-(T rimethoxysilyl)methyl)methacrylamide, N- (Trimethoxysilyl)methyl)cyclohexanamine, N,N'-(Methoxy(methyl)silanediyl)dibenzamide and the corresponding compounds in which all methoxy groups are replaced either by ethoxy groups or by propoxy groups, e.g. methyltriethoxysilane, etc.

[0057] In a preferred embodiment of the invention, all groups X are alkoxy groups, particularly preferably methoxy and / or ethoxy groups.

[0058] According to the preceding description, crosslinkers V, in particular crosslinkers V of the general formula (III), can be fully or partially hydrolyzed and condensed to form siloxanes. Such condensed siloxanes can be prepared from one or more different crosslinkers of the general formula (III), wherein at least one of the underlying crosslinkers is a trialkoxysilane or a tetraalkoxysilane, and wherein the average degree of condensation of the siloxane is preferably at least 4. The siloxane is thus preferably an alkoxy-containing condensation product of the monomeric alkoxysilanes of the general formula (III).

[0059] Mono-, di-, tri-, or tetraalkoxysilanes or mixtures thereof can be used for the partial hydrolysis and condensation, with at least one alkoxysilane being a tri- or tetraalkoxysilane. Depending on the alkoxysilanes used and the reaction procedure, in particular the amount of water added, the degree of condensation and the proportion of alkoxy groups remaining in the siloxane formed can be adjusted, with the average degree of condensation of the siloxane preferably being at least 4. The siloxane can consist of linear and / or branched chains, rings, or cages. It is clear to the person skilled in the art that mixtures of such structural elements are usually present. The alkoxysilanes can have non-hydrolyzable groups bonded to the Si atom, in particular monovalent hydrocarbon radicals, which optionally have one or more functional groups, which remain in the siloxane formed. The alcohol formed as a by-product can be removed, e.g.by evaporation in a vacuum. Siloxanes containing alkoxy groups are known and commercially available.

[0060] In addition, monoalkoxysilanes and / or dialkoxysilanes can also be used to produce the alkoxy-containing siloxane. Examples include trimethylmethoxysilane, triethylmethoxysilane, triphenylmethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, and diphenyldimethoxysilane, as well as the corresponding silanes in which all methoxy groups are replaced by either ethoxy or propoxy groups. The monoalkoxysilanes and / or dialkoxysilanes can be used, for example, to adjust the degree of condensation or branching of the resulting siloxane.

[0061] Preferred tri- or tetraalkoxysilanes used to prepare the alkoxy-containing siloxane are methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 2-aminoethyl-3-aminopropyltrimethoxysilane, 2-aminoethyl-3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, tetraethoxysilane, tetramethoxysilane, and mixtures thereof.

[0062] In preferred embodiments of the moisture-curing

[0063] Silicone composition comprises crosslinker V an amino group-containing

[0064] Alkoxysilane or -siloxane, in particular one selected from 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and oligomeric siloxanes obtained from the partial condensation of at least one of these silanes and optionally other silanes. These embodiments are particularly preferred in cases where organotin compounds are used as catalyst K.

[0065] The use of an amino-containing alkoxysilane or siloxane as a component of crosslinker V has the advantage that the amino group (especially in the presence of a primary amino group) accelerates the curing of the silicone composition. Furthermore, crosslinkers V containing amino groups can improve adhesion to many substrates.

[0066] In the same or other preferred embodiments of the moisture-curing silicone composition, crosslinker V comprises an oligomeric siloxane, in particular an oligomeric siloxane with alkoxysilane groups and vinyl groups. These embodiments are particularly preferred in cases where organotin compounds are used as catalyst K. In embodiments where a titanate is used as catalyst K, crosslinker V preferably does not comprise an oligomeric siloxane.

[0067] The use of oligomeric siloxanes as a component of the crosslinker V has the advantage that the amount of cleavage alcohol formed during the crosslinking of the alkoxysilane group-containing crosslinker V and polydiorganylsiloxane polymers P is reduced, which reduces the amount of VOC (volatile organic carbon) and makes the composition even less problematic with regard to EHS (environment, health and safety).

[0068] The moisture-curing silicone composition preferably contains between 1 wt.% and 7.5 wt.%, in particular between 1.5 wt.% and 5 wt.%, preferably between 2 wt.% and 4.5 wt.% of crosslinker V, based on the total composition. It is preferred that crosslinker V comprises at least one amino-group-containing alkoxysilane or -siloxane. Furthermore, it is preferred that crosslinker V comprises at least one oligomeric siloxane, in particular an oligomeric siloxane with alkoxysilane groups and vinyl groups. These embodiments are particularly preferred in cases where organotin compounds are used as catalyst K.

[0069] In particularly preferred embodiments, the moisture-curing silicone composition comprises between 1 wt.% and 2.5 wt.% of crosslinker V according to formula (III), in particular with R 5selected from vinyl, phenyl and propyl groups, and additionally between 0.5 and 1.5 wt.% of crosslinker V, which is an oligomeric siloxane, in particular an oligomeric siloxane with alkoxysilane groups and / or vinyl groups.

[0070] Condensation catalyst K

[0071] The composition according to the invention further contains at least one condensation catalyst K. This serves to catalyze the hydrolysis and condensation taking place between the crosslinkable polydiorganylsiloxane P and the crosslinker V in the presence of moisture or water.

[0072] The condensation catalyst K can be any catalyst commonly used for these systems, and is preferably a metal catalyst. Metal catalysts can, in particular, be compounds or complexes of elements from groups 1, 2, 4, 12, 14, or 15 of the Periodic Table of the Elements, preferably from groups 4 or 14. The condensation catalyst K is preferably an organotin compound or a titanate or organotitanate. The condensation catalyst is most preferably an organotin compound. These are commercially available. It is also possible, and in certain cases even preferred, to use mixtures of different catalysts as the condensation catalyst K.

[0073] Preferred organotin compounds for this purpose are

[0074] Dialkyltin compounds, e.g. selected from dimethyltin di-2-ethylhexanoate, dimethyltin dilaurate, di-n-butyltin diacetate, di-n-butyltin di-2-ethylhexanoate, di-n-butyltin dicaprylate, di-n-butyltin di-2,2-dimethyloctanoate, di-n-butyltin dilaurate, di-n-butyltin distearate, di-n-butyltin dimaleate, di-n-butyltin dioleate, di-n-octyltin di-2-ethylhexanoate, di-n-octyltin di-2,2-dimethyloctanoate, di-n-octyltin dimaleate, di-n-octyltin dilaurate, di-n-butyltin oxide and di-n-octyltin oxide.

[0075] Suitable organotin compounds can be purchased commercially, for example, from TIB, Germany.

[0076] Titanates or organotitanates are compounds that have at least one ligand bonded to the titanium atom via an oxygen atom. Suitable ligands bonded to the titanium atom via an oxygen-titanium bond include, for example, those selected from an alkoxy group, sulfonate group, carboxylate group, dialkyl phosphate group, dialkyl pyrophosphate group, and acetylacetonate group. Preferred titanates include tetrabutyl or tetraisopropyl titanate. Other suitable titanates have at least one multidentate ligand, also called a chelate ligand. In particular, the multidentate ligand is a bidentate ligand.

[0077] Suitable titanates are commercially available, for example, under the trade names Tyzor® AA-105, PITA, TnBT, TPT, TOT, IAM, IBAY from Dorf Ketal, India.

[0078] Zirconates, bismuthates, and aluminates are also preferred. Zirconates, bismuthates, and aluminates are also suitable as condensation catalyst K.

[0079] Suitable zirconates are commercially available, for example, under the trade names Tyzor® NBZ, NPZ, TEAZ, 212, 215, 217, 223 from Dorf Ketal, or under the trade names K-Kat 4205 or K-Kat XC-6212 from King Industries. Suitable bismuthates include, in particular, bismuth carboxylates. Bismuth carboxylates can be prepared from Bi(III) compounds with the organic acids R-COOH using processes known from the literature or are available as commercially available products under the respective brand names, such as bismuth trioctoate or bismuth trineodecanoate, for example under the brand names Borchi® Kat (Borchers GmbH) or Tegokat® (Goldschmidt TIB GmbH), Neobi® 200 (Shepherd), Coscat®, and Caschem. Other suitable bismuthates are available, for example, under the trade names K-Kat 348 and K-Kat XC-8203 from King Industries.

[0080] A suitable aluminate is available, for example, under the trade name K-Kat 5218 from King Industries.

[0081] Also suitable as condensation catalyst K are amidines and guanidines, in particular those as described in WO 2016 / 207156, in WO 2013 / 087680, and in WO 2015 / 193208.

[0082] The moisture-curing silicone composition preferably contains between 0.01 wt.% and 5 wt.%, in particular between 0.025 wt.% and 4 wt.%, preferably between 0.03 wt.% and 2.5 wt.% of condensation catalyst K, based on the total composition. In embodiments in which an organotin compound is used as condensation catalyst K, the preferred content of condensation catalyst K is in particular between 0.025 wt.% and 1 wt.%.

[0083] In embodiments in which a titanate is used as condensation catalyst K, the preferred content of condensation catalyst K is in particular between 1.5 wt.% and 2.5 wt.%.

[0084] Ground chalk GK

[0085] The composition according to the invention contains at least one ground chalk GK, which constitutes at least the major portion of all fillers contained, wherein the ground chalk GK has a particle size d50, determined according to the standard ISO 13320:2009, of more than 0.6 pm and less than 2 pm.

[0086] The particle size specification, or synonymously particle size d50, refers to the fact that 50% by weight of the particles have a size equal to or smaller than the specified value. The particle size d50 can typically be determined by laser light scattering according to the ISO 13320:2009 standard, for example, using the CILAS 920 device from CILAS or the Malvern Mastersizer 3000 device from Malvern Panalytical.

[0087] The at least one ground chalk GK must constitute at least the majority of all fillers contained, which means that the ground chalk GK, based on all fillers contained in the composition, accounts for more than 50 wt.%, preferably more than 75 wt.%, in particular more than 80 wt.% of all fillers contained, based on the total weight of all fillers contained. Further fillers are described below.

[0088] It is essential for the invention that ground chalk is used, rather than precipitated chalk. Precipitated chalks contain excessive water due to their manufacturing process, which is difficult to completely remove even with complex drying measures. However, the high water content impairs storage stability, especially in the case of RTV-1 compositions containing alkoxysilane-functional polymers and crosslinkers, as is the case in the present invention.

[0089] The at least one ground chalk GK has an exceptionally small particle size d50 of less than 2 pm and more than 0.6 pm, in particular between 0.7 pm and 1.6 pm, preferably between 0.7 pm and 1 pm, particularly preferably between 0.7 pm and 0.9 pm. With this property, the ground chalk GK can contribute significantly to the advantages according to the invention. If the ground chalk has a particle size d50 of 2 pm or more, the tear propagation resistance decreases significantly, especially when using an organotin condensation catalyst K. At the same time, the storage stability decreases significantly if the particle size d50 of the ground chalk GK is 0.6 pm or less. In addition, ground chalks with particle sizes d50 below 0.6 pm are difficult to produce, and the chalks have a noticeably higher water content, which negatively affects the storage stability of the silicone composition.

[0090] The ground chalk can be coated or uncoated. Suitable coatings are known to those skilled in the art and include, for example, stearate coatings and silane coatings.

[0091] Suitable and preferred ground chalks GK are, for example, Calatem® C16T (Provengale), Calatem® CT (Provengale), Calatem® 06NGT (Provengale), Omyabond® 120 (Omya), Omyabond® 420 (Omya), Omyabond® 460 (Omya) and Omyabond® 520 (Omya).

[0092] Ground chalk GK normally has a beneficially low water content due to its manufacturing process. Nevertheless, it can be advantageous to additionally dry the ground chalk GK for storage stability (particularly with RTV-1 compositions). Suitable methods for this include vacuuming at elevated temperatures, e.g., at least 60°C, preferably 80°C to 100°C, or without vacuum at 120°C for an extended period, e.g., 24 hours. The water content of ground chalk GK is preferably <0.2 wt.%, in particular <0.1 wt.%, based on the total weight of the ground chalk GK.

[0093] In preferred embodiments of the moisture-curing silicone composition, the silicone composition contains between 30 wt.% and 70 wt.%, preferably between 40 wt.% and 60 wt.%, in particular between 45 wt.% and 55 wt.% of ground chalk GK, based on the total composition. In addition to the ground chalk GK, the silicone composition optionally contains one or more further fillers. These further fillers can, for example, influence both the rheological properties of the uncured composition and the mechanical properties and surface quality of the cured composition. It can be advantageous to use different fillers in one composition.

[0094] The composition according to the invention may contain, for example, 1 to 15% by weight, preferably 2 to 10% by weight, of further fillers.

[0095] Examples of suitable additional fillers are inorganic or organic fillers, such as natural, ground chalks with particle sizes d50 of more than 2 pm or precipitated chalks, both of which are optionally surface-treated, e.g. with fatty acids; silicic acids, in particular pyrogenic silicic acids, which are optionally surface-treated, e.g. with silicone oils; aluminum hydroxides such as aluminum trihydroxide; carbon black, in particular industrial carbon black; barium sulfate, dolomite; silicas; kaolin; hollow spheres; quartz; calcined aluminum oxides; aluminum silicates; magnesium aluminum silicates; zirconium silicates;

[0096] Cristobalite flour; diatomaceous earth; mica; titanium oxides; zirconium oxides; gypsum; graphite; carbon fibers; zeolites; and glass fibers, the surface of which may be treated with a hydrophobic agent.

[0097] The composition according to the invention preferably does not contain precipitated silica, since this may impair the storage stability of the composition.

[0098] Fumed silicas, however, are possible and preferred. The addition of fumed silicas improves the stability and thixotropic properties of the composition.

[0099] The moisture-curing silicone composition thus preferably additionally contains a, preferably hydrophobized, pyrogenic silica, in particular in an amount of between 1 wt.% and 15 wt.%, preferably between 2 wt.% and 10 wt.%, based on the total composition.

[0100] Optional additional ingredients

[0101] The composition according to the invention may optionally contain further components such as those customary for moisture-curing, condensation-curing silicone compositions. Such additional components include, for example, plasticizers, adhesion promoters, curing accelerators, OH scavengers, drying agents, wetting aids, rheology modifiers, thixotropic agents, processing aids, biocides, UV stabilizers, heat stabilizers, flame retardants, color pigments, odorants, antistatic agents, and emulsifiers.

[0102] The composition according to the invention preferably contains at least one of these optional further ingredients.

[0103] An example of plasticizers that may be used are trialkylsilyl-terminated polydimethylsiloxanes, whereby the trialkylsilyl-terminated polydimethylsiloxanes preferably have a viscosity at 23°C in the range of 1 to 10,000 mPa s. It is also possible to use trimethylsilyl-terminated polydimethylsiloxanes, for example, in which some of the methyl groups are replaced by other organic groups such as phenyl, vinyl or trifluoropropyl groups. The polydimethylsiloxane can also be monofunctional, i.e. one end is reactive, e.g. via a hydroxy end group. Certain hydrocarbons can also be used as plasticizers. Suitable hydrocarbons can be purchased commercially, for example, under the trade name Hydroseal G 232 H from Total.

[0104] Examples of adhesion promoters that may be used are amino alcohols such as triethanolamine or amine-containing polyols, which are commercially available, for example, under the trade name Jeffamin®. Compounds containing silyl groups that carry hydrolyzable residues on the silicon atom, especially aminosilanes such as 3-aminopropyltrimethoxysilane, are classified as crosslinkers of general formula (III) because they can participate in the crosslinking reaction.

[0105] It may be advantageous to combine two or more adhesion promoters.

[0106] The optionally used curing accelerators are compounds which accelerate the crosslinking of the moisture-curing, condensation-crosslinking composition when used together with the inventive condensation catalyst K. Examples of such curing accelerators are guanidines, in particular silylated guanidines or oligodiorganylsiloxanes modified with guanidine groups, diorganosulfoxides, imidazoles, in particular alkylated imidazoles such as N-methylimidazole or benzimidazole, amidines, in particular silylated amidines or oligodiorganylsiloxanes modified with amidine groups or cyclic amidines such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and amines, in particular alkylamines such as triethylamine or silylated amines such as N-butyl-3-aminopropyltrimethoxysilane. Curing accelerators containing alkoxysilyl groups also act as crosslinking agents.

[0107] Curing accelerators can be added in amounts of 0 to 5 wt%, preferably 0.01 to 2 wt%, based on the total weight of the moisture-curing composition. The curing accelerator can consist of a single substance or a mixture of two or more substances.

[0108] The optionally used OH scavengers are compounds that react with any OH groups present. OH groups can be present as uncapped chain ends of polydiorganylsiloxanes, as OH groups on fillers, and as water. OH scavengers can be Si-N-containing compounds. Examples of OH scavengers are hexamethyldisilazane (HMDZ), hexamethylcyclotrisilazane, octamethyltetrasilazane, and bis(trimethylsilyl)urea. HMDZ is the most preferred OH scavenger.

[0109] The moisture-curing silicone composition preferably further contains an acid or its conjugate base, which potentially exerts a buffering effect within the composition and stabilizes the composition, thus increasing storage stability. Weak to medium-strength acids are particularly suitable, preferably those with pKa values ​​between 4 and 8.

[0110] Suitable and preferred such acids are, for example, carboxylic acids such as fatty acids, neodecanoic acid or acetic acid, as well as optionally partially esterified phosphoric or phosphonic acids.

[0111] Preferably, the composition additionally contains between 0.1 wt.% and 1.5 wt.%, preferably between 0.2 wt.% and 1.0 wt.%, based on the total composition, of an acid or its conjugate base, preferably a partially esterified phosphoric acid and / or a partially esterified phosphonic acid.

[0112] The composition according to the invention most preferably contains at least one partially esterified phosphoric or phosphonic acid. Diesters are preferred for phosphoric acid esters, and monoesters for phosphonic acid esters. In particular, these esters contain precisely one P-OH group. Examples of such partially esterified phosphoric or phosphonic acids are commercially available, for example under the trade names Stabilizer POP® from Wacker, TIB STAB® 115 from TIB, or Lakeland® TPA 800 from Lakeland.

[0113] Most preferably, this acid is pre-complexed with the condensation catalyst K and added to the formulation as a mixture. Such pre-mixing results in particularly good storage stability of the composition. For organotin catalysts, it is particularly advantageous to set a molar ratio of phosphoric or phosphonic acid ester to tin atoms of at least 1, preferably 1 to 3, most preferably 2.

[0114] The moisture-curing silicone composition preferably contains, as an additional component, a polymer PE with polyether structural units. The addition of polymer PE with polyether structural units is particularly preferred when an organotin compound is used as the condensation catalyst K. The term "polyether structural unit" means that a polyether structure, in particular a polyoxyalkylene structure such as a polyoxyethylene or polyoxypropylene structure, must be present at least partially in a main or secondary polymer chain of the polymer PE. The polymer PE may also contain other functionalities or polymer chain components without a polyether structure, such as hydroxyl groups, amino groups, silane groups, polydiorganylsiloxane chains, or polyolefin chains.

[0115] However, it is preferred if the PE polymer has at least one hydroxyl group and / or at least one amino group, and in particular, does not contain any silane groups, polydiorganylsiloxane chains, and / or polyolefin chains. Such PE polymers lead to particularly good storage stability in the composition, especially in tin-catalyzed formulations.

[0116] In preferred embodiments of the composition according to the present invention, the composition contains a polymer PE with polyether structural units, which in particular does not have any silane groups, polydiorganylsiloxane chains and / or polyolefin chains.

[0117] The presence of a PE polymer with polyether structural units in the composition has the advantage of increasing storage stability and improving the stability of the cured composition. This effect is particularly pronounced in embodiments in which an organotin compound is used as the condensation catalyst K.

[0118] However, if a titanate is used as condensation catalyst K, the composition preferably does not contain polymer PE.

[0119] The moisture-curing silicone composition preferably additionally contains a polymer PE with polyether structural units and preferably at least one hydroxyl and / or amino group, in particular in an amount of between 0.5 wt.% and 7.5 wt.%, preferably between 1 wt.% and 7 wt.%, based on the total composition. All components of the moisture-curing, condensation-curing composition can be mixed together in the usual way. For this purpose, the individual components are thoroughly mixed together in suitable mixing units, e.g., compulsory mixers, planetary mixers, mixing tubes, kneaders, dissolvers, or extruders. Mixing can take place continuously or in a batch process.The crosslinkable polydiorganylsiloxane P according to the invention, in particular one of the general formula (I) or formula (Ia), can be prepared in a prior, spatially separate reaction, optionally stored temporarily, and then metered into the mixing unit in a suitable amount. Alternatively, it is also possible, and in some cases preferred, to prepare the crosslinkable polydiorganylsiloxane P, in particular one of the general formula (I) or formula (Ia), directly in the mixing unit as described above and to meter in and mix the other ingredients after completion of this preparation, without processing and / or intermediate storage of the polydiorganylsiloxane P.

[0120] The composition according to the invention can be a two-component composition, consisting of a component A comprising a) the at least one polydiorganylsiloxane P b) optionally fillers c) optionally further ingredients and a component B comprising a) the at least one condensation catalyst K b) the at least one crosslinker V c) optionally fillers d) optionally further ingredients, wherein the ground chalk GK can be contained in one or both of component A and / or B.

[0121] Components A and B of this two-component, moisture-curing composition are kept separate for storage. Components A and B can be mixed in the usual way, e.g., by stirring component B into component A, which can be done manually or using a suitable stirring device, e.g., a static mixer, dynamic mixer, speed mixer, dissolver, etc. The two components can also be squeezed out of the separate storage containers and mixed for application or introduction, e.g., using gear pumps. Mixing can take place, for example, in supply lines or nozzles for application or introduction, or directly on the substrate or in the joint.

[0122] The composition according to the invention can be a one-component composition. In a preferred embodiment, the composition according to the invention is a one-component composition.

[0123] The composition according to the invention can be used as an adhesive or sealant in a process for bonding or jointing substrates.

[0124] Thus, one aspect of the invention is a method for bonding or jointing substrates.

[0125] The method for bonding or jointing substrates with a moisture-curing composition according to the present invention and the previous description comprises: a) optionally mixing any components of the composition stored in different containers to obtain a complete mixture of all ingredients of the composition, b) applying the fully mixed composition to a substrate and bringing the mixture applied to the substrate into contact with another substrate to obtain an adhesive bond between the substrates, or introducing the mixture into a joint between two substrates to obtain a bond between the substrates, and c) curing the composition thus applied. In the case of one-component systems, by exposure to moisture, in particular atmospheric humidity.Any mixing required in step a) can therefore be performed before or during application or introduction according to step b). Mixing should be performed shortly before further processing, as the curing process begins with mixing. Naturally, step a) is omitted when using an RTV-1 formulation.

[0126] Application to a substrate or introduction into a joint between substrates according to step b) can be carried out in a conventional manner, e.g., by hand or in an automated process using robots. In bonding, the substrate coated with the mixture is brought into contact with another substrate, optionally under pressure, to obtain an adhesive bond between the substrates. Subsequently, in step c), the mixture is allowed to cure, usually at room temperature, to achieve the bonding or joining of the substrates. In this way, the bonded or jointed substrates according to the invention are obtained with the cured mixture as an adhesive or sealing material.

[0127] The substrates to be bonded or jointed can be made of the same or different materials. All conventional materials can be bonded or jointed with the two-component composition according to the invention. Preferred materials for bonding or jointing are glass, metals such as aluminum, copper, steel, or stainless steel, concrete, mortar, building blocks such as sandstone and sand-lime brick, asphalt, bitumen, plastics such as polyolefins, PVC, Tedlar, PET, polyamide, polycarbonate, polystyrene, or polyacrylate, and composite materials such as CFRP.

[0128] The composition according to the invention can thus be used as an adhesive or sealant, for example, in the fields of construction, plumbing, automotive, solar technology, wind power technology, white goods, facade and window construction, electronics, and boat and ship building. Accordingly, a further subject of the invention is the use of a composition according to the invention as described above as an adhesive, sealant, coating, or potting compound, in particular in the fields of construction, plumbing, automotive construction and maintenance, solar technology, wind power technology, white goods, facade and window construction, electronics, and boat and ship building.

[0129] A further subject of the invention are bonded or grouted substrates obtainable by a process as just described.

[0130] Examples

[0131] The following describes specific embodiments of the invention, but these are not intended to limit the scope of the invention. All tests were conducted at 23°C and 50% RH (relative humidity).

[0132] The proportions of the components for the silicone compositions listed in the tables below were weighed one after the other and mixed in a Hauschild speed mixer at 23°C and 50% RH for 20 seconds at 2000 rpm under vacuum. All numerical values ​​of the ingredients in all tables indicate parts by weight (e.g., in grams) of the respective ingredient added to the respective composition. The resulting compositions were sealed hermetically, stored at 23°C for 24 hours, and then tested.

[0133] The Shore A hardness was determined after 7 days of curing using a Bareiss Shore A testing device in accordance with DIN ISO 7619-1. To determine Shore A hardness, round test specimens with a diameter of 42 mm and a thickness of 6 mm were prepared. The method for determining elongation at break and tensile strength, as well as the preparation of the required test specimens, is described in ISO 527. Measurements were taken at 23°C and 50% relative humidity using a Type 1 B test specimen (ISO 527-2) and at a tensile speed of 200 mm / min. The composites were preliminarily ironed into 2 mm thick sheets and cured for 7 days.

[0134] The method for determining tear resistance (WRW) and the preparation of the required test specimens are described in DIN ISO 34-1. Measurements were performed on Type C test specimens.

[0135] To determine the skin formation time, the composition to be tested was applied to an area of ​​approximately 20 cm2 spread to a thickness of approximately 1 cm. Care was taken to ensure the surface was smooth. The time of spreading marked the start of the measurement. A PE pipette was applied to the surface of the hardening composition. The skin formation time was reached when the PE pipette could be removed without visible adhesion.

[0136] The viscosity was determined according to DIN EN ISO 3219 using a cone-plate viscometer MCR101 from Anton-Paar, Austria, with a cone type CP 25-1 and a distance of 0.049 mm at 23°C. The stated viscosity values ​​refer to a shear rate of 0.1 s -1 .

[0137] Abbreviations of the chemicals used can be found in Table 1 below. All polymers are based on linear polydimethylsiloxane (PDMS). Unless otherwise stated, all chemicals are commercially available from chemical retailers (e.g., Sigma-Aldrich).

[0138] Table 1 :

[0139] Table 1 : Ingredients used.

[0140] Polymers P1 and P2 were purchased directly from Wacker; the synthesis of PDMS polymers with alkyloxy end groups is described, for example, in US2008207938A1.

[0141] The preparation of the catalysts used for the synthesis of polymers P3 to P6 is described in WO 2016 / 207156, WO 2013 / 087680, and WO 2015 / 193208.

[0142] Polymer P3

[0143] 100 g of linear OH-PDMS with a viscosity of 120,000 mPa s was mixed with 3 g of vinyltrimethoxysilane. 40 mg of 1,1'-(α,wn-propyl-poly(dimethylsiloxane))-bis(2,3-dicyclohexylguanidine) was added to this reaction mixture. The mixture was stirred for 5 h at 40°C. Subsequently, no further gelation was observed upon adding a few drops of tetra-n-propyl orthotitanate to a small sample of the polymer, indicating the completeness of the reaction. The resulting polymer is stable in storage and can be used without further processing.

[0144] Polymer P4

[0145] Polymer P4 was prepared analogously to Polymer 3, replacing the polymer with a linear OH-PDMS with a viscosity of 80,000 mPa s.

[0146] Polymer P5

[0147] Polymer P5 was prepared analogously to Polymer 3, replacing the polymer with a linear OH-PDMS with a viscosity of 50,000 mPa s.

[0148] Polymer P6

[0149] Polymer P6 was prepared analogously to Polymer 3, replacing the polymer with a linear OH-PDMS with a viscosity of 20,000 mPa s. Influence of the particle size of the ground chalk GK

[0150] A series of single-component compositions were prepared (tests E1 to E8), differing only in the type of ground chalk used as filler. All ground chalks used were coated with stearate and differed primarily in particle size.

[0151] The basic formulation of tests E1 to E8 is shown in Table 2, the details of the ground chalks used in Table 3. Table 4 shows all tests E1 to E8 with the corresponding measurement data.

[0152] Table 2: Basic formulation of experiments E1 to E8.

[0153] Table 3: Details of the chalks used GK.

[0154] Table 4: Measurement results of tests E1 to E8. * not according to the invention

[0155] Reference tests, «n / m» means not measured, «n / h» means that the silicone compound was not cured after 7 days of curing under standard conditions (standard climate).

[0156] The results in Table 4 show that the inventive GK chalks lead to particularly good mechanical properties of the composition (in particular, high tensile strength combined with high elongation at break). Even more surprising is the exceptionally high tear resistance exhibited by the inventive compositions. These properties are largely retained even after artificial aging of the composition. In contrast, non-inventive chalks with too small particle size (E7) or precipitated chalks (E8) exhibit good tear resistance in the fresh state, but they exhibit completely inadequate storage stability and do not harden at all after artificial aging. Artificial aging was carried out in all examples by storing a prepared sample in a sealed container at 70°C for 7 days.With such heat storage, the storage stability of a composition can be determined through simulated, accelerated aging.

[0157] Influence of the amount of ground chalk GK

[0158] A series of tests E9 to E16 were conducted with varying proportions of ground chalk GK. The details of these tests and the corresponding measurement results are shown in Table 5. The numbers in the formulations indicate parts by weight of the respective ingredient. The ingredients are specified in Tables 1 and 3.

[0159] Table 5: Formulation details and measurement results of experiments E9 to E16. Influence of the chain length of polydiisocyanate P

[0160] A series of tests E17 to E24 were conducted with various polymers P of varying chain lengths. The details of these tests and the corresponding measurement results are shown in Table 6. The numbers in the formulations indicate parts by weight of the respective ingredient. The ingredients are specified in Tables 1 and 3.

[0161] "n / m" means not measured. * Non-inventive reference experiments.

[0162] Influence of PE polymers with polyether structural units. A series of tests E25 to E30 were conducted with various PE polymers with polyether structural units. The details of these tests and the corresponding measurement results are shown in Table 8. The numbers in the formulations indicate parts by weight of the respective ingredient. The ingredients are specified in Tables 1 and 7.

[0163] Table 7: Details of the polymers with polyether structural units used.

[0164] Table 8: Formulation details and measurement results of tests E25 to E30.

[0165] «n / m» means not measured, «nh» means not cured.

[0166] Table 8 shows that polymers with polyether structural units as additives can significantly contribute to additional improvement of storage stability, especially if they are hydroxyl- or amine-functional.

[0167] Influence of catalyst K and acid

[0168] A series of experiments E31 to E38 were conducted with different catalysts K, or in different amounts. The details of these experiments and the corresponding measurement results are shown in Tables 9 and 10. The numbers in the formulations indicate parts by weight of the respective ingredient. The ingredients are specified in Tables 1 and 7. Experiments E31 to E38 demonstrate the influence of different ratios of acid to catalyst K on the properties of the composition. In each case, the acid was added together with the catalyst at the end of the formulation. Experiments E39 to E46 demonstrate the influence of the acid on the storage stability in tin-catalyzed formulations. In some experiments, the acid was pre-reacted with the catalyst and added as a mixture. In comparison, in Experiment E46, the acid was added together with the crosslinkers.The pre-reaction of the acid with the tin catalyst can be followed by NMR spectroscopy: In. 31 P NMR shows a change in the chemical shift when a phosphate ester is complexed to tin (from 0.25 ppm for a free monoester or 1.45 ppm for a free diester to -3.2 ppm for a phosphate ligand complexed to tin). The same is true in 1 19 SN-NMR spectrum can be observed: When all tin atoms of the catalyst are complexed by phosphate ligands, the chemical shift changes from -160 ppm (catalyst K1 or K3 as used) to -262 ppm (ligand exchange with complexation of phosphoric acid esters). Table 9: Formulation details and measurement results of tests E31 to E38. "n / m" means not measured. Table 10: Formulation details and measurement results of tests E39 to E46. "n / m" means not measured. 1 Catalyst K and acid were pre-reacted and added as a mixture. 2Acid was added together with crosslinker V.

Claims

Patent claims 1. Moisture-curing silicone composition comprising a) at least one crosslinkable polydiorganylsiloxane P with alkoxysilane end groups; b) at least one condensation catalyst K; c) at least one crosslinker V with alkoxysilane groups; d) at least one ground chalk GK, which makes up at least the majority of all fillers contained; e) optionally further ingredients, in particular an unreactive polydiorganylsiloxane as a plasticizer, characterized in that the ground chalk GK has a particle size d50, determined according to the standard ISO 13320:2009, of more than 0.6 pm and less than 2 pm.

2. Moisture-curing silicone composition according to claim 1, characterized in that the crosslinkable polydiorganylsiloxane P is prepared in a condensation reaction from OH-terminated polydiorganylsiloxane and a tri- or tetraalkoxysilane, preferably a methyltrialkoxysilane or a vinyltrialkoxysilane.

3. Moisture-curing silicone composition according to claim 2, characterized in that the reaction of the OH-terminated polydiorganylsiloxane with the tri- or tetraalkoxysilane is carried out in the presence of an amidine or guanidine catalyst.

4. Moisture-curing silicone composition according to one of the preceding claims, characterized in that crosslinker V is an amino group-containing alkoxysilane or siloxane selected from 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and oligomeric siloxanes obtained from the partial condensation of at least one of these silanes and optionally further silanes.

5. Moisture-curing silicone composition according to one of the preceding claims, characterized in that the condensation catalyst K is a compound of an element of groups 1, 2, 4, 12, 14 or 15 of the Periodic Table of the Elements, preferably a compound of groups 4 or 14, particularly preferably of titanium or tin, very particularly preferably an organotin compound.

6. Moisture-curing silicone composition according to one of the preceding claims, characterized in that the silicone composition contains between 30 wt.% and 70 wt.%, preferably between 40 wt.% and 60 wt.%, in particular between 45 wt.% and 55 wt.% of ground chalk GK, based on the total composition.

7. Moisture-curing silicone composition according to one of the preceding claims, characterized in that the composition additionally contains between 0.1 wt.% and 1.5 wt.%, preferably between 0.2 wt.% and 1.0 wt.%, based on the total composition, of an acid or its conjugate base, preferably a partially esterified phosphoric acid and / or a partially esterified phosphonic acid, which is preferably complexed with the condensation catalyst K 8. Moisture-curing silicone composition according to one of the preceding claims, characterized in that the composition additionally contains a polymer PE with polyether structural units and preferably at least one hydroxyl and / or amino group, in particular in an amount of between 0.5 wt% and 7.5 wt%, preferably between 1 wt% and 7 wt%, based on the total composition.

9. Moisture-curing silicone composition according to claim 8, characterized in that the polymer PE does not contain any silane groups, polydiorganylsiloxane chains and / or polyolefin chains.

10. Moisture-curing silicone composition according to one of the preceding claims, characterized in that the composition additionally contains a, preferably hydrophobized, pyrogenic silica, in particular in an amount of between 1 wt.% and 10 wt.%, preferably between 2 wt.% and 5 wt.%, based on the total composition. 11 . Moisture-curing silicone composition according to one of the preceding claims, characterized in that the crosslinker V comprises an oligomeric siloxane, in particular an oligomeric siloxane with alkoxysilane groups and vinyl groups.

12. Moisture-curing silicone composition according to one of the preceding claims, characterized in that OH-terminated polydimethylsiloxanes, plasticizers, adhesion promoters, curing accelerators, OH scavengers, drying agents, wetting aids, rheology modifiers, thixotropic agents, processing aids, biocides, UV stabilizers, heat stabilizers, flame retardants, color pigments, odorants, antistatic agents, and / or emulsifiers are included as further ingredients.

13. Moisture-curing silicone composition according to one of claims 1 to 12, characterized in that the composition is a one-component silicone composition.

14. Use of a composition according to any one of the preceding claims as an adhesive, sealant, coating or potting compound, in particular in the fields of construction, sanitary, automotive construction and maintenance, solar technology, wind power technology, white goods, facade and window construction, electronics and boat and ship building.

15. A method for bonding or jointing substrates with a moisture-curing composition according to any one of claims 1-13, comprising a) optionally mixing any components of the composition stored in different containers to obtain a complete mixture of all ingredients of the composition, b) applying the completely mixed composition to a substrate and bringing the mixture applied to the substrate into contact with another substrate to obtain an adhesive bond between the substrates, or introducing the mixture into a joint between two substrates to obtain a bond between the substrates, and c) curing the composition thus applied by exposure to moisture, in particular atmospheric humidity.

16. Bonded or grouted substrates obtainable by a process according to claim 15.

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