Moisture curing RTV-silicone compositions with high tear strength and storage stability

Abstract

Described is a moisture-curable silicone composition comprising at least one crosslinkable polydiorganosiloxane having alkoxysilane end groups, at least one condensation catalyst, at least one crosslinking agent having alkoxysilane groups, at least one ground chalk, which constitutes at least the main part of all the contained fillers, optionally further ingredients, characterized in that the ground chalk has a particle size d50, measured according to ISO 13320: 2009 standard, of greater than 0.6 m and less than 2 m. The compositions are particularly suitable as low modulus sealants and have excellent tear strength and excellent storage stability, in particular even in the form of RTV-1 formulations.

Description

Technical Field

[0001] This invention relates to moisture-curing, condensation-crosslinking silicone compositions, their use as elastic adhesives and sealants, and methods for bonding and adhering substrates. Background Technology

[0002] Silicone is a known composition that has long been used as an adhesive or sealant. Silicones can be formulated as one-component or two-component silicone compositions and typically contain crosslinkable polydiorganosiloxanes, crosslinking agents, and catalysts as main components. They are classified into cold-crosslinked RTV-silicone (RTV = room temperature crosslinking or vulcanization) and hot-crosslinked HTV-silicone (HTV = high temperature crosslinking or vulcanization). One-component and two-component RTV-silicone are also referred to as RTV-1 silicone or RTV-2 silicone, respectively.

[0003] Condensation-crosslinked, moisture-curing RTV silicones are already known. It is also known that such compositions can be cured based on so-called neutral crosslinking. Traditionally, neutrally crosslinked RTV-1 silicones release oxime compounds, whose odor is considered highly unpleasant, undesirable for occupational health reasons, and increasingly restricted by law. As an alternative to oxime-releasing compositions, neutrally crosslinked RTV-1 silicones can also be formulated using polydiorganosiloxanes containing alkoxysilyl groups. The cleavage products of crosslinking are merely alcohols, typically methanol or ethanol, cleaved from the alkoxysilyl groups, with far less problematic odor and toxicological characteristics than oximes.

[0004] Polydiorganosiloxanes used in condensation-crosslinked moisture-curing silicones can be end-capped with hydroxyl groups. However, it has been found that such end groups limit achievable properties and cause significant problems during the compounding process, particularly in the case of RTV-1 silicones. Alternatively, polydiorganosiloxanes can be modified with alkyldialkoxysilyl or trialkoxysilyl end groups. Such modified polymers are already known. For example, the preparation of such modified polymers by condensation reactions is described in EP763557 or EP0559045; and the preparation of such modified polymers by hydrosilylation reactions is described in US4898910.

[0005] For applications as low-modulus sealants (such as joint sealants in the bathroom industry), one-component silicones, i.e., RTV-1 silicones, are typically used. If such silicones are formulated with polydiorganosiloxanes with alkyldialkoxysilyl or trialkoxysilyl end groups and coupled with a tin-based curing catalyst, relatively high-modulus cured compositions unsuitable for use as sealants are usually obtained. Using titanate-based curing catalysts instead of tin-based curing catalysts partially solves this problem. However, RTV-1 silicones with titanate catalysts containing polydiorganosiloxanes with alkyldialkoxysilyl or trialkoxysilyl end groups generally exhibit insufficient storage stability. These sealants may thicken in closed containers due to undesirable reactions, or, worse, fail to cure altogether.

[0006] Furthermore, RTV silicones often suffer from insufficient tear strength. This manifests, for example, as microcracks in the cured composition rapidly propagate under minimal external force, eventually leading to localized cohesive or adhesive tearing or breakage of the cured material. This is undesirable for any application but can usually only be mitigated to some extent through meticulous formulation and optimization, often at the cost of reduced other properties (e.g., mechanical properties of the material) or higher manufacturing costs. For instance, EP0649879 discloses a silicone composition containing a special filler combination consisting of precipitated silica surface-modified with hexamethyldisilazane and precipitated calcium carbonate coated with stearate, along with a tin catalyst. By using these highly specialized fillers, the tear strength of the silicone composition can be improved. A drawback of the composition according to EP0649879 is the difficulty and high cost of preparing these specialized fillers. The precipitated chalk also typically contains a significant amount of water resulting from the preparation process, requiring very complex drying, especially when used in RTV-1 silicones, as storage stability cannot otherwise be guaranteed.

[0007] As another example, EP2641934 also discloses silicone compositions with improved tear strength, an effect achieved through a special combination of fillers and a special combination of catalysts.

[0008] The disadvantages of the composition disclosed in EP2641934 are that the composition has a high viscosity, making it difficult to apply manually or even pump, and it also poses potential risks to the environment or health because several different organometallic catalysts must be used.

[0009] As another example, WO2018033563 discloses a silicone composition with improved tear strength, achieved specifically by combining two polydiorganosiloxane polymers with different reactivity in a specific molar ratio. A drawback of the WO2018033563 approach is that the formulation freedom is limited by a narrow selection of polymers, which relates to potential performance limitations and higher formulation costs. Therefore, there is a need for an easily prepared, condensation-crosslinked, moisture-curing silicone composition based on polydiorganosiloxanes with alkoxysilyl end groups, suitable as a low-modulus sealant with excellent tear strength and excellent storage stability, thereby overcoming the shortcomings of the prior art.

[0010] EP1043356 discloses a one-component silicone composition containing a polyether siloxane and fine chalk fillers with a particle size of up to 4.5 µm. The composition disclosed in this document exhibits a particularly low modulus and good adhesion properties. However, tear strength was not investigated, and ground chalk is not preferred. Summary of the Invention

[0011] Therefore, the object of the present invention is to provide a moisture-curing RTV silicone composition based on the condensation crosslinking of polydiorganosiloxanes with alkoxysilyl end groups, which has excellent tear strength and excellent storage stability, and can be used as a one-component low-modulus sealant.

[0012] Surprisingly, it was found that when milled chalk with a particle size of less than 2 µm was used as a filler in RTV silicone compositions of alkoxysilane-terminated polydiorganosiloxane polymers, an unexpectedly high improvement in tear strength could be achieved, which was particularly surprising when using organotin catalysts. Furthermore, in the preferred embodiments, exceptionally good storage stability was achieved, particularly even when using titanate-based catalysts (which are typically particularly problematic in terms of storage stability).

[0013] Therefore, this invention relates to a condensation-crosslinked, moisture-curing silicone composition comprising:

[0014] a) at least one crosslinkable polydiorganosiloxane P having an alkoxysilane end group;

[0015] b) At least one condensation catalyst K;

[0016] c) At least one crosslinking agent V having an alkoxysilyl group;

[0017] d) At least one milled chalk GK, which constitutes at least the main part of all the included fillers;

[0018] e) Optional other components, especially non-reactive polydiorganosiloxanes as plasticizers;

[0019] The characteristic feature is that the particle size d50 of the ground chalk GK, as determined according to ISO 13320:2009 standard, is greater than 0.6µm and less than 2µm.

[0020] The invention will be explained in detail below. Detailed Implementation

[0021] The viscosities given in this article can be determined according to DIN 53018. They can be measured at 23°C using an Anton-Paar MCR101 cone-plate viscometer (Kegel-Typ CP 25-1) from Austria. The viscosity values ​​given per 0.5 s⁻¹ are for reference only. -1 The shear rate.

[0022] Crosslinking reactions include hydrolysis and condensation reactions of alkoxysilyl groups. These are known to those skilled in the art and can be illustrated as follows.

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

[0024] ≡Si-OH + HO-Si≡ → ​​≡Si-O-Si≡ + H2O (2)

[0025] By adding water and optionally using a catalyst, alkoxysilyl groups hydrolyze to form silanols (Si-OH) and alcohols (step 1). Silanols are generally unstable and spontaneously condense to form siloxane bonds (-Si-O-Si-), thus forming siloxanes (step 2). If each silicon atom has more than one alkoxy group, a more highly condensed system can be formed. In the case of partial hydrolysis, only a portion of the alkoxy groups are hydrolyzed and condensed. The reaction rate of the crosslinking reaction depends on the kinetics of the sub-steps. These kinetics can be, for example, in single-component reactions. 1 H NMR and 29 Si was determined in NMR experiments, as described in “Zeitschrift für Naturforschung (1999), 54b, 155-164” and “Phosphorus, Sulfur, and Silicone and the Related Elements (2011), 186(2), 240-254”.

[0026] The term "uniform deep curing" used in this article means that the silicone composition cures uniformly across its entire cross-section within the joint. This means that the properties of the silicone composition after curing on both the front and back sides of the joint (particularly mechanical properties such as hardness and elasticity) are the same within their respective measurement accuracy ranges.

[0027] The composition according to the present invention comprises:

[0028] a) at least one crosslinkable polydiorganosiloxane P having an alkoxysilane end group;

[0029] b) At least one condensation catalyst K;

[0030] c) At least one crosslinking agent V having an alkoxysilyl group;

[0031] d) At least one milled chalk GK, which constitutes at least the main part of all the included fillers;

[0032] e) Optional other components, especially non-reactive polydiorganosiloxanes as plasticizers;

[0033] The characteristic feature is that the particle size d50 of the ground chalk GK, as determined according to ISO 13320:2009 standard, is greater than 0.6µm and less than 2µm.

[0034] The composition of the present invention is a condensation-crosslinked, moisture-curing RTV-silicone. It can exist as a one-component composition (RTV-1 silicone), wherein all components are mixed together and the mixture is stored with moisture removed. This RTV-1 silicone is cured by contact with water (typically by contact with moisture in the air). Alternatively, it can exist as a two-component composition (RTV-2). The composition of the present invention is preferably present as a one-component RTV-1 silicone composition.

[0035] Polydiorganosiloxane P with alkoxysilane end groups

[0036] The compositions of the present invention comprise at least one crosslinkable polydiorganosiloxane P having an alkoxysilane end group. Such crosslinkable polydiorganosiloxanes are well known to those skilled in the art. Crosslinkable polydiorganosiloxanes have functional groups capable of crosslinking, particularly two or more functional groups. These functional groups may be present in the side groups or end groups of the polydiorganosiloxane, with terminal functional groups being preferred. Such polydiorganosiloxanes having terminal functional groups are also referred to as α,ω-functionalized polydiorganosiloxanes. The functional group of at least one crosslinkable polydiorganosiloxane P is an alkoxy group.

[0037] The viscosity of the polydiorganosiloxane P used can vary over a wide range depending on the intended use. The viscosity of the polydiorganosiloxane used in this invention at 23°C is, for example, 10 to 500,000 mPa s, preferably 5,000 to 400,000 mPa s, and particularly preferably 6,000 to 350,000 mPa s.

[0038] Crosslinkable polydiorganosiloxane P is preferably a linear polydiorganosiloxane, particularly a polydiorganosiloxane of formula (I):

[0039]

[0040] Wherein group R 1 R 2 and R 3 Each of the above represents a linear or branched monovalent hydrocarbon group having 1 to 12 C atoms, which optionally has one or more heteroatoms and optionally has one or more C-multiple bonds and / or optionally has an alicyclic and / or aromatic moiety.

[0041] In particular, the group R 1 and R 2 This indicates an alkyl group having 1 to 5, particularly 1 to 3, carbon atoms, preferably methyl. The group R 3 Each of these can be used independently to specifically indicate phenyl, vinyl, or methyl.

[0042] Group R 4 Each of the above independently represents an alkoxy group having 1 to 13 C atoms, optionally having one or more heteroatoms and optionally having one or more C C multiple bonds and / or optionally having an alicyclic and / or aromatic moiety.

[0043] In formula (I), Y is a divalent hydrocarbon group having 1 to 8 carbon atoms, preferably 2 to 6 carbon atoms, particularly preferably an ethylene bridge or a hexene bridge, or an oxygen atom, or a group of general formula (II).

[0044]

[0045] Where R 3 It has the above meaning, and l=1-5.

[0046] The exponent m in general formula (I) is selected such that the polydiorganosiloxane P has, for example, the viscosity described above at a temperature of 23°C. The exponent m in general formula (I) can be in the range of 10 to 10,000, preferably in the range of 100 to 1,500.

[0047] Polydiorganosiloxane P of formula (I), especially polydiorganosiloxane of formula (Ia).

[0048]

[0049] Where R 1 R 2 R 3 R 4 And m have the same meaning and the same preferred embodiment as the polydiorganosiloxane P of formula (I).

[0050] At least one crosslinkable polydiorganosiloxane P is an alkoxy-terminated polydiorganosiloxane, preferably a crosslinkable alkoxy-terminated polydimethylsiloxane. The preferred crosslinkable polydiorganosiloxane used is a linear polydiorganosiloxane. Therefore, the group R in formula (I) or formula (Ia) 4 Alkoxy groups having 1 to 8 carbon atoms are preferred independently of each other, and may optionally be substituted with F, N, P, O and / or S.

[0051] Group R in formula (I) or formula (Ia) 3 It may be selected independently from one or more of the following: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl, isohexyl, n-heptyl, isoheptyl, n-octyl, isooctyl, cyclopentyl, cyclohexyl, phenyl, vinyl, allyl, methoxymethyl, 2-methoxyethyl, ethoxymethyl, 2-(2-methoxyethoxy)ethyl, trifluoropropyl, 2-aminoethyl, 6-aminohexyl.

[0052] The group R in formulas (I) and (Ia) 3 Preferably, the alkyl groups are selected independently from each other and have 1 to 6, particularly 1 to 3, carbon atoms, such as propyl, ethyl, and methyl, with ethyl and methyl being preferred and methyl being particularly preferred.

[0053] In a particular implementation, all groups R in formulas (I) and (Ia) 3 They are all the same and are selected from alkyl groups having 1 to 6, particularly 1 to 3, carbon atoms, such as propyl, ethyl and methyl, wherein methyl and ethyl are preferred, and methyl is particularly preferred.

[0054] The polydiorganosiloxane of general formula (I) and / or formula (Ia) preferably accounts for at least 90%, more preferably at least 95%, and particularly preferably at least 99% of the total mass of the polydiorganosiloxane P present in the composition of the present invention.

[0055] Suitable polydiorganosiloxanes as shown in formula (I) and / or formula (Ia) are known and commercially available. The preparation of such polydiorganosiloxanes is carried out by known methods and procedures, as described in EP0658588.

[0056] Polydiorganosiloxanes of general formula (Ia) can be prepared by a condensation reaction of an OH-terminated polydiorganosiloxane with an alkoxy-functionalized silane or siloxane. Preparation by condensation reaction can be carried out according to, for example, the methods described in EP763557 or EP0559045. Alternatively, polydiorganosiloxanes of general formula (I) can be prepared by a hydrosilylation reaction of a vinyl-terminated polydiorganosiloxane with a Si-H functionalized alkoxysilane or siloxane, or by a hydrosilylation reaction of a Si-H-terminated polydiorganosiloxane with a vinyl-functionalized alkoxysilane or siloxane. Preparation by hydrosilylation reaction can be carried out according to, for example, the methods described in US4898910.

[0057] In a preferred embodiment, polydiorganosiloxanes of general formula (I) and formula (Ia) are prepared by a condensation reaction of an OH-terminated polydiorganosiloxane with an alkoxy-functionalized silane or siloxane. In a particularly preferred embodiment, polydiorganosiloxanes of general formula (I) and formula (Ia) are prepared by a condensation reaction of an OH-terminated polydiorganosiloxane with an alkoxy-functionalized silane or siloxane under the catalysis of an amidine or guanidine (optionally under the co-catalysis of a metal catalyst). Suitable amidine and guanidine catalysts are described, for example, in WO 2016 / 207156 and WO 2015 / 193208.

[0058] In a preferred embodiment of the moisture-curing silicone composition, the crosslinkable polydiorganosiloxane P is prepared by the condensation reaction of an OH-terminated polydiorganosiloxane with a trialkoxysilane or a tetraalkoxysilane, wherein the trialkoxysilane is preferably a methyltrialkoxysilane or a vinyltrialkoxysilane.

[0059] In a particularly preferred embodiment of the moisture-curing silicone composition, the reaction of the OH-terminated polydiorganosiloxane with a trialkoxysilane or a tetraalkoxysilane is carried out in the presence of an amidine catalyst or a guanidine catalyst.

[0060] Based on the entire composition, the moisture-curing silicone composition preferably contains between 10% and 60% by weight, particularly between 15% and 50% by weight, and preferably between 20% and 40% by weight of polydiorganosiloxane P.

[0061] Crosslinking agent V with alkoxysilyl group

[0062] The compositions of the present invention further comprise at least one crosslinking agent V having an alkoxysilyl group. The alkoxysilyl group is a hydrolyzable group that can optionally react with the functional groups of the polydiorganosiloxane to form a siloxane bond, provided that it has been pre-hydrolyzed to form a silanol group. The reaction between the functional groups of the polydiorganosiloxane and the hydrolyzable group of the crosslinking agent is preferably carried out by a condensation reaction, optionally following the hydrolysis of the at least one alkoxysilyl group involved. Byproducts, such as water or alcohol, are typically released at this time.

[0063] The crosslinking agent V of the present invention, having a hydrolyzable group, particularly conforms to general formula (III).

[0064] R 5 n SiX 4-n (III)

[0065] Where R 5 Each of the components is an independent, non-hydrolyzable monovalent hydrocarbon group having 1 to 18 carbon atoms, which may be saturated or unsaturated and optionally have one or more functional groups containing elements F, N, P, O and / or S, n equal to 0, 1, 2 or 3, preferably 0 or 1, and X is an OH group or a straight-chain or branched alkoxy group having 1 to 8 carbon atoms, which may optionally be substituted with F, N, P, O and / or S and optionally have unsaturated and / or alicyclic and / or aromatic portions.

[0066] If X represents an alkoxy group, then the alkoxy group X is independently selected from one or more of the following: methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, pentooxy, isopentoxy, hexoxy, isohexoxy, heptoxy, isohexoxy, octoxy, isooctoxy, cyclopentoxy, cyclohexoxy, phenoxy, ethoxy, allyloxy, methoxymethoxy, 2-methoxyethoxy, ethoxymethoxy, 2-(2-methoxyethoxy)ethoxy, trifluoropropoxy, 2-aminoethoxy, and 6-aminohexoxy.

[0067] The alkoxy group X is preferably selected independently from alkoxy groups having 1 to 6, particularly 1 to 3, carbon atoms, such as propoxy, ethoxy and methoxy, with methoxy and ethoxy being preferred, and methoxy being particularly preferred.

[0068] In a particular embodiment, all groups X are identical and are selected from alkoxy groups having 1 to 6, particularly 1 to 3, carbon atoms, such as propoxy, ethoxy, and methoxy, with methoxy and ethoxy being preferred, and methoxy being particularly preferred.

[0069] Examples of crosslinking agents of general formula (III) are methyltrimethoxysilane, dimethyldimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, isobutyltrimethoxysilane, octyltrimethoxysilane, hexadecyltrimethoxysilane, vinyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, vinyldimethoxymethylsilane, phenyltrimethoxysilane, tetramethyl orthosilicate, 3-methacryloyloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-aminopropyltrimethoxysilane. Silanes, 3-epoxypropoxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 2-aminoethyl-3-aminopropyltrimethoxysilane, (trimethoxysilyl)methyl-O-methylcarbamate, N-((trimethoxysilyl)methyl)methacrylamide, N-((trimethoxysilyl)methyl)cyclohexylamine, N,N'-(methoxy(methyl)silanediyl)dibenzoamide, and corresponding compounds in which all methoxy groups are replaced by ethoxy or propoxy groups, such as methyltriethoxysilane, etc.

[0070] In a preferred embodiment of the invention, all groups X are alkoxy, particularly preferably methoxy and / or ethoxy.

[0071] According to the above description, crosslinking agent V, particularly crosslinking agent V of general formula (III), can be completely or partially hydrolyzed and condensed to form a siloxane. This condensed siloxane can be prepared from one or more different crosslinking agents of general formula (III), wherein at least one basic crosslinking agent is a trialkoxysilane or a tetraalkoxysilane, and wherein the average degree of condensation of the siloxane is preferably at least 4. Therefore, the siloxane is preferably a condensation product of a monomeric alkoxysilane of general formula (III) containing an alkoxy group.

[0072] Partial hydrolysis and condensation can be performed using mono-, di-, tri-, or tetra-alkoxysilanes or mixtures thereof, wherein at least one alkoxysilane is a tri- or tetra-alkoxysilane. The degree of condensation and the proportion of residual alkoxy groups in the formed siloxane can be adjusted depending on the alkoxysilane used and the reaction scheme, particularly the amount of water added, wherein the average degree of condensation of the siloxane is preferably at least 4. The siloxane can be composed of straight-chain and / or branched, cyclic, or cage-like structures. It is apparent to those skilled in the art that mixtures of such structural units are commonly present. The alkoxysilane may have optional non-hydrolyzable groups (particularly monovalent hydrocarbon groups) bonded to Si atoms, which are retained in the formed siloxane. Alcohols formed as byproducts can be removed, for example, by vacuum evaporation. Alkoxy-containing siloxanes thus formed are known and commercially available.

[0073] Furthermore, monoalkoxysilanes and / or dialkoxysilanes can be used to prepare alkoxy-containing siloxanes. Examples are trimethylmethoxysilane, triethylmethoxysilane, triphenylmethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, and diphenyldimethoxysilane, as well as the corresponding silanes in which all methoxy groups are replaced by ethoxy or propoxy groups. For example, monoalkoxysilanes and / or dialkoxysilanes can be used to adjust the degree of condensation or branching of the resulting siloxane.

[0074] Preferred trialkoxysilanes or tetraalkoxysilanes for preparing alkoxysilanes are methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 2-aminoethyl-3-aminopropyltrimethoxysilane, 2-aminoethyl-3-aminopropyltriethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, tetraethoxysilane, tetramethoxysilane, and mixtures thereof.

[0075] In a preferred embodiment of the moisture-curing silicone composition, the crosslinking agent V comprises an amino-containing alkoxysilane or alkoxysiloxane, particularly selected from one of the following: 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane, N-(2-aminoethyl)-3-aminopropyl-methyldimethoxysilane, and oligomeric siloxanes obtained by partial condensation of at least one of these silanes and optionally other silanes. This embodiment is particularly preferred when an organotin compound is used as catalyst K.

[0076] The advantage of using amino-containing alkoxysilanes or alkoxysiloxanes as components of crosslinking agent V is that the amino group (especially in the presence of a primary amino group) accelerates the curing of the silicone composition. Furthermore, crosslinking agent V containing amino groups can improve adhesion on many substrates.

[0077] In the same or other preferred embodiments of the moisture-curing silicone composition, the crosslinking agent V comprises an oligomeric siloxane, particularly an oligomeric siloxane having an alkoxysilyl group and a vinyl group. This embodiment is particularly preferred when an organotin compound is used as catalyst K. In embodiments using titanate as catalyst K, the crosslinking agent V preferably does not contain an oligomeric siloxane.

[0078] The advantage of using oligomeric siloxanes as a component of crosslinking agent V is that the amount of pyrolytic alcohols formed during the crosslinking of the alkoxysilyl group-containing crosslinking agent V and the polydiorganosiloxane polymer P is reduced. This reduces the amount of VOCs (volatile organic carbons) and makes the composition less problematic in terms of EHS (environment, health, and safety).

[0079] Based on the overall composition, the moisture-curing silicone composition preferably contains between 1% and 7.5% by weight, particularly between 1.5% and 5% by weight, and preferably between 2% and 4.5% by weight, of a crosslinking agent V. Preferably, the crosslinking agent V contains at least one amino-containing alkoxysilane or alkoxysiloxane. More preferably, the crosslinking agent V contains at least one oligomeric siloxane, particularly an oligomeric siloxane having an alkoxysilyl group and a vinyl group. This embodiment is particularly preferred when using an organotin compound as catalyst K.

[0080] In a particularly preferred embodiment, the moisture-curing silicone composition comprises between 1% and 2.5% by weight of a crosslinking agent V of formula (III), particularly R. 5 It is selected from vinyl, phenyl and propyl, and also contains between 0.5 wt% and 1.5 wt% of a crosslinking agent V, said crosslinking agent V being an oligopolysiloxane, particularly an oligopolysiloxane having an alkoxysilyl group and / or vinyl.

[0081] Condensation catalyst K

[0082] The compositions of the present invention further comprise at least one condensation catalyst K. The condensation catalyst K is used to catalyze the hydrolysis and condensation between a crosslinkable polydiorganosiloxane P and a crosslinking agent V in the presence of moisture or water.

[0083] The condensation catalyst K can be any commonly used catalyst for these systems, with a preference for metal catalysts. Metal catalysts are particularly compounds or complexes of elements from Groups 1, 2, 4, 12, 14, or 15 of the periodic table (preferably Group 4 or 14). The condensation catalyst K is preferably an organotin compound or a titanate or organotitanate. Organotin compounds are particularly preferred as the condensation catalyst. They are commercially available. In certain cases, it is possible, and even preferred, to use a mixture of different catalysts as the condensation catalyst K.

[0084] For this purpose, the preferred organotin compound is a dialkyltin compound, such as selected from dimethyltin di-2-ethylhexanoate, dimethyltin dilaurate, dibutyltin diacetate, dibutyltin di-2-ethylhexanoate, dibutyltin dioctanoate, dibutyltin dioctanoate, dibutyltin di-2,2-dimethyloctanoate, dibutyltin dilaurate, dibutyltin distearate, dibutyltin dimaleate, dibutyltin dioleate, dioctyltin di-2-ethylhexanoate, dioctyltin di-2,2-dimethyloctanoate, dioctyltin dimaleate, dioctyltin dilaurate, dioctyltin di-2-butyltin oxide, and dioctyltin oxide.

[0085] Suitable organotin compounds can be obtained, for example, from the German company TIB.

[0086] Titanate or organotitanate refers to a compound having at least one ligand bonded to a titanium atom via an oxygen atom. Suitable ligands bonded to the titanium atom via an oxygen-titanium bond are selected, for example, from: alkoxy, sulfonate, carboxylate, dialkyl phosphate, dialkyl pyrophosphate, and acetylacetone groups. Preferred titanates are, for example, tetrabutyl titanate or tetraisopropyl titanate. Furthermore, suitable titanates have at least one polydentate ligand (also referred to as a chelating ligand). In particular, the polydentate ligand is a bidentate ligand.

[0087] Suitable titanates, for example, are available under the brand name Tyzor. ® AA-105, PITA, TnBT, TPT, TOT, IAM, and IBAY were purchased from Dorf Ketal in India.

[0088] Zirconates, bismuthates, and aluminates are also preferred. Zirconates, bismuthates, and aluminates are also suitable as condensation catalysts K.

[0089] Suitable zirconates are available, for example, from DorfKetal under the trademarks Tyzor® NBZ, NPZ, TEAZ, 212, 215, 217, 223, or from King Industries under the trademarks K-Kat 4205 or K-Kat XC-6212.

[0090] Suitable bismuthates, particularly bismuth carboxylate, are available. Bismuth carboxylate can be prepared from Bi(III) compounds with the organic acid R-COOH according to methods known in the literature, and is also available as a commercial product under various trade names (such as bismuth trioctanoate or bismuth tridecanoate), for example, the trade names Borchi® Kat (Fa. Borchers GmbH) or Tegokat® (Fa. Goldschmidt TIB GmbH), Neobi®200 (Fa. Shepherd) or Coscat® (Fa. Caschem). Other suitable bismuthates are available, for example, from King Industries under the trade names K-Kat 348 and K-Kat XC-8203.

[0091] Suitable aluminates are available, for example, from King Industries under the trademark K-Kat 5218.

[0092] Other suitable condensation catalysts for K are amidine and guanidine, especially those described in WO 2016 / 207156, WO 2013 / 087680 and WO 2015 / 193208.

[0093] Based on the entire composition, the moisture-curing silicone composition preferably contains between 0.01 wt% and 5 wt%, particularly between 0.025 wt% and 4 wt%, and preferably between 0.03 wt% and 2.5 wt% of condensation catalyst K. In embodiments using an organotin compound as condensation catalyst K, the preferred content of condensation catalyst K is particularly between 0.025 wt% and 1 wt%.

[0094] In embodiments where titanate is used as condensation catalyst K, the preferred content of condensation catalyst K is particularly between 1.5% by weight and 2.5% by weight.

[0095] Grinded chalk GK

[0096] The compositions of the present invention comprise at least one milled chalk GK, which constitutes at least the main part of all the included fillers, wherein the particle size d50 of the milled chalk GK, as determined according to standard ISO 13320:2009, is greater than 0.6 µm and less than 2 µm.

[0097] The particle size, or d50, data here refers to the size of 50% by weight of particles that is equal to or smaller than a given value. Particle size d50 can typically be determined by laser scattering according to standard ISO 13320:2009, for example using a CILAS 920 instrument from CILAS Corporation or a Malvern Mastersizer 3000 instrument from Malvern Panalytical Corporation.

[0098] The at least one type of ground chalk GK must constitute at least a major portion of all the included fillers, meaning that, based on the total weight of all the included fillers in the composition, the ground chalk GK accounts for more than 50% by weight, preferably more than 75% by weight, and particularly more than 80% by weight of all the included fillers. Other fillers will be further described below.

[0099] Importantly for this invention is the use of ground chalk rather than precipitated chalk. Precipitated chalk contains too much water due to its preparation, which is difficult to remove completely 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 crosslinking agents, as is the case with this invention.

[0100] At least one type of milled chalk GK has an extremely small particle size d50 of less than 2 µm and greater than 0.6 µm, particularly between 0.7 µm and 1.6 µm, preferably between 0.7 µm and 1 µm, and especially preferably between 0.7 µm and 0.9 µm. This characteristic significantly contributes to the advantages of the present invention. If the particle size d50 of the milled chalk is 2 µm or greater, the tear strength decreases significantly, especially when using organotin condensation catalyst K. Simultaneously, when the particle size d50 of the milled chalk GK is 0.6 µm or smaller, the storage stability decreases significantly. Furthermore, milled chalk with a particle size d50 below 0.6 µm can only be prepared in a complex manner, and the chalk has a significantly higher water content, which adversely affects the storage stability of the silicone composition.

[0101] The abrasive chalk can be coated or uncoated. Suitable coatings are known to those skilled in the art, including, for example, stearate coatings and silane coatings.

[0102] Suitable and preferred grinding chalk GK is, for example, Calatem. ® C16T (Provençale), Calatem ® CT (Provençale), Calatem ® 06NGT (Provençale), Omyabond ® 120 (Omya), Omyabond ® 420 (Omya), Omyabond ® 460 (Omya) and Omyabond ® 520 (Omya).

[0103] Ground chalk GK typically has an advantageously low water content due to its preparation. However, for storage stability (especially in the case of RTV-1 compositions), additional drying of the ground chalk GK is advantageous. For this purpose, it is suitable, for example, to perform vacuum treatment at high temperatures (e.g., at least 60°C, preferably 80°C to 100°C), or to perform treatment without vacuum at 120°C for an extended period (e.g., 24 hours). Based on the total weight of the ground chalk GK, the water content of the ground chalk GK is preferably <0.2% by weight, particularly <0.1% by weight.

[0104] In a preferred embodiment of the moisture-curing silicone composition, the silicone composition comprises, based on the whole composition, 30% to 70% by weight, preferably 40% to 60% by weight, and particularly 45% to 55% by weight of ground chalk GK.

[0105] In addition to ground chalk GK, the silicone composition optionally contains one or more other fillers. These other fillers can affect not only the rheological properties of the uncured composition but also the mechanical properties and surface quality of the cured composition. Using different fillers in a single composition may be advantageous.

[0106] The compositions of the present invention may contain, for example, 1% to 15% by weight, preferably 2% to 10% by weight, other fillers.

[0107] Examples of other suitable fillers are inorganic or organic fillers, such as naturally ground chalk or precipitated chalk with a particle size d50 greater than 2 µm, both of which are optionally surface-treated, for example with fatty acids; silica, especially pyrogenetic silica, which is optionally surface-treated, for example with silicone oil; aluminum hydroxide, such as aluminum trihydroxide; carbon black, especially industrial carbon black; barium sulfate; dolomite; silica; kaolin; hollow beads; quartz; calcined alumina; aluminum silicate; magnesium aluminum silicate; zirconium silicate; cristobalite powder; diatomaceous earth; mica; titanium dioxide; zirconium oxide; gypsum; graphite; carbon fiber; zeolite; and glass fiber with a surface optionally treated with a hydrophobic agent.

[0108] The compositions of the present invention are preferably free of precipitated silica, as this may impair the storage stability of the compositions.

[0109] Conversely, pyrolytic silica is possible and preferred. The addition of pyrolytic silica improves the composition's anti-sagging and thixotropic properties.

[0110] The moisture-curing silicone composition therefore preferably also contains preferably hydrophobic pyrolytic silica, and in particular, the amount of said pyrolytic silica is between 1% and 15% by weight, preferably between 2% and 10% by weight, based on the whole composition.

[0111] Optional other ingredients

[0112] The compositions of the present invention may optionally also contain other components as commonly found in condensation-crosslinked moisture-curing silicone compositions. These additional components include, for example, plasticizers, tackifiers, curing accelerators, OH scavengers, desiccants, wetting agents, rheology modifiers, thixotropic agents, processing aids, biocides, UV stabilizers, heat stabilizers, flame retardants, color pigments, fragrances, antistatic agents, and emulsifiers.

[0113] The compositions of the present invention preferably contain at least one of the optional other ingredients.

[0114] Examples of optional plasticizers include trialkylsilyl-terminated polydimethylsiloxanes, wherein the trialkylsilyl-terminated polydimethylsiloxanes preferably have a viscosity in the range of 1 to 10,000 mPa·s at 23°C. Trimethylsilyl-terminated polydimethylsiloxanes may also be used, for example, in which some methyl groups are replaced by other organic groups (e.g., phenyl, vinyl, or trifluoropropyl). Polydimethylsiloxanes may also be monofunctional, i.e., reactive at one end, for example, via a hydroxyl terminal group. Certain hydrocarbons can also be used as plasticizers. Suitable hydrocarbons can be commercially available, for example, from Total under the trade name Hydroroseal G 232 H.

[0115] Examples of optional tackifiers are amino alcohols, such as triethanolamine or amine-containing polyols, for example, through the brand name Jeffamin. ® Commercially available. Compounds containing silyl groups and hydrolyzable groups on the Si atom, especially aminosilanes such as 3-aminopropyltrimethoxysilane, are crosslinking agents of general formula (III) because they can participate in crosslinking reactions.

[0116] Combining two or more tackifiers may be advantageous.

[0117] The optional curing accelerator is a compound that promotes crosslinking of the wet-cured composition when used with the condensation catalyst K of the present invention. Examples of such curing accelerators are guanidine, particularly silylated guanidine or oligomeric diorganosiloxanes modified with guanidine groups, diorganosulfoxides, imidazoles, particularly alkylated imidazoles such as N-methylimidazolium or benzimidazole, amidines, particularly silylated amidines or oligomeric diorganosiloxanes modified with amidine groups or cyclic amidines such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and amines, particularly alkylamines such as triethylamine, or silylated amines such as N-butyl-3-aminopropyltrimethoxysilane. Curing accelerators containing alkoxysilyl groups also act as crosslinking agents.

[0118] Based on the total weight of the wet-curing composition, the curing accelerator may be added in an amount of 0% to 5% by weight, preferably 0.01% to 2% by weight. The curing accelerator may consist of a single substance or a mixture of two or more substances.

[0119] The optional OH scavenger is a compound that reacts with the optional OH groups. The OH groups can exist as unclosed chain ends of polydiorganosiloxanes, OH groups on fillers, and water. The OH scavenger can be a Si-N containing compound. Examples of OH scavengers are hexamethyldisilazane (HMDZ), hexamethylcyclotrisilazane, octamethyltetrasilazane, and bis(trimethylsilyl)urea. HMDZ is the most preferred OH scavenger.

[0120] The moisture-curing silicone composition further preferably contains an acid or its conjugate base, which may exhibit a buffering effect within the composition and stabilize the composition, thereby improving storage stability. Particularly suitable are weak to moderately strong acids, preferably those with pKs values ​​between 4 and 8.

[0121] Suitable and preferred acids are, for example, carboxylic acids, such as fatty acids, neodecanoic acid, or acetic acid, and optionally partially esterified phosphoric acid or phosphonic acid.

[0122] Preferably, based on the whole composition, the composition further contains between 0.1% by weight and 1.5% by weight, preferably between 0.2% by weight and 1.0% by weight, of an acid or its conjugate base, preferably partially esterified phosphoric acid and / or partially esterified phosphonic acid.

[0123] Very particularly preferred, the compositions of the present invention comprise at least one partially esterified phosphoric acid or phosphonic acid. The phosphate ester is preferably a diester, and the phosphonate is preferably a monoester. In particular, these esters contain only one p-OH group. An example of such partially esterified phosphoric acid or phosphonic acid is, for instance, Stabilizer POP, a trademark of Wacker. ® TIB's trademark name is TIB STAB. ® 115 or Lakeland's trademark Lakeland ® TPA 800 was purchased commercially.

[0124] The acid is particularly preferably pre-compounded with the condensation catalyst K and added to the formulation as a mixture. This premix results in a composition with particularly good storage stability. In the case of organotin catalysts, it is particularly advantageous to adjust the molar ratio of phosphate ester or phosphonate to tin atoms to at least 1, preferably 1 to 3, and most preferably 2.

[0125] Moisture-curing silicone compositions preferably contain a polymer PE having polyether structural units as an additional component. When using an organotin compound as the condensation catalyst K, the addition of a polymer PE having polyether structural units is particularly preferred. The term "polyether structural unit" means that the main polymer chain or side polymer chains of the polymer PE must at least partially contain a polyether structure, particularly a polyoxyalkylene structure, such as a polyoxyethylene or polyoxypropylene structure. Furthermore, the polymer PE may have other functional groups or polymer chain portions without polyether structures, such as hydroxyl, amino, silyl, polydiorganosiloxane chains, or polyolefin chains.

[0126] However, it is preferred that the polymer PE has at least one hydroxyl group and / or at least one amino group, and in particular, it does not have silyl groups, polydiorganosiloxane chains, and / or polyolefin chains. Such polymer PE results in particularly good storage stability in the composition (especially in tin-catalyzed formulations).

[0127] In a preferred embodiment of the composition of the present invention, the composition comprises a polymer PE having a polyether structural unit, wherein the polymer PE is particularly free of silane groups, polydiorganosiloxane chains and / or polyolefin chains.

[0128] The presence of the polymer PE with polyether structural units in the composition has the advantage of improved storage stability and enhanced stability of the cured composition. This effect is particularly pronounced in embodiments using an organotin compound as the condensation catalyst K.

[0129] However, if titanate is used as condensation catalyst K, the composition is preferably free of polymer PE.

[0130] The moisture-curing silicone composition preferably further comprises a polymer PE having polyether structural units and preferably at least one hydroxyl and / or amino group. Specifically, the amount of the polymer PE is between 0.5% and 7.5% by weight, preferably between 1% and 7% by weight, based on the entire composition. All components of the condensation-crosslinked moisture-curing composition can be mixed with each other in a conventional manner. For this purpose, the individual components are thoroughly mixed with each other in a suitable mixing device (e.g., a forced mixer, planetary mixer, mixing tube, kneader, dissolver, or extruder). Mixing can be carried out continuously or in batches. The crosslinkable polydiorganosiloxane P of the present invention, particularly polydiorganosiloxane P of general formula (I) or formula (Ia), can be prepared by a pre-emptive spatially isolated reaction, optionally with intermediate storage, and then metered into a mixing device in a suitable amount. It is also possible, and in some cases preferred, that crosslinkable polydiorganosiloxane P, particularly polydiorganosiloxane P of general formula (I) or formula (Ia), can be prepared directly in the above-mentioned mixing equipment, and after preparation, other components are metered and mixed, without the need for processing and / or intermediate storage of polydiorganosiloxane P.

[0131] The composition of the present invention can be a two-component composition consisting of component A and component B, wherein component A comprises:

[0132] a) At least one polydiorganosiloxane P

[0133] b) Optional filler

[0134] c) Optional other ingredients

[0135] Component B comprises:

[0136] a) at least one condensation catalyst K

[0137] b) At least one crosslinking agent V

[0138] c) Optional filler

[0139] d) Other optional ingredients,

[0140] The ground chalk GK may be included in one or both of components A and / or B.

[0141] In this two-component moisture-curing composition, components A and B are stored separately. Mixing of components A and B can be done in common ways, such as by mixing component B into component A, which can be done manually or with the aid of a suitable stirring device (e.g., a static mixer, dynamic mixer, high-speed mixer, dissolver, etc.). For application or introduction, the two components can also be extruded and mixed from separate storage containers, for example, using a gear pump. Here, mixing can be done, for example, in an inlet tube or nozzle for application or introduction, or directly on the substrate or in the seam.

[0142] The compositions of the present invention can be one-component compositions. In a preferred embodiment, the compositions of the present invention are one-component compositions.

[0143] The compositions of the present invention can be used as adhesives or sealants in methods for bonding or joining substrates.

[0144] Therefore, one aspect of the present invention is a method for bonding or joining substrates.

[0145] The method of bonding or joining substrates using the aforementioned moisture-curing composition of the present invention includes:

[0146] a) Optional mixing of composition components stored in different containers to obtain a complete mixture of all components of the composition.

[0147] b) Applying the fully mixed composition to a substrate and bringing the mixture onto another substrate into contact to achieve an adhesive bond between the substrates, or introducing the mixture into the seam between two substrates to achieve a joint between the substrates, and

[0148] c) Curing the composition thus applied. Single-component systems rely on the action of moisture (especially air moisture).

[0149] Therefore, the optional mixing according to step a) can be performed before or during the application or introduction according to step b). Mixing should be performed shortly before further processing, as the curing process begins with the mixing. Of course, step a) is omitted when using the RTV-1 formulation.

[0150] The application of the mixture to the substrate or its introduction into the joint between substrates, as described in step b), can be performed in a common manner, such as manually or by means of a robot in an automated process. During bonding, optionally under pressure, the substrate to which the mixture is applied is brought into contact with another substrate to achieve an adhesive bond between the substrates. Then, in step c), the mixture is typically cured at room temperature, thereby achieving the bonding or joining of the substrates. In this way, substrates with the cured mixture as an adhesive or sealant according to the invention are obtained.

[0151] The substrates to be bonded or joined can be composed of the same or different materials. All common materials can be bonded or joined using the two-component compositions of the present invention. Preferred materials for bonding or joining are glass, metals (e.g., aluminum, copper, steel, or stainless steel), concrete, mortar, building stone (e.g., sandstone and limestone bricks), asphalt, tar, plastics (e.g., polyolefins, PVC, tedlar, PET, polyamide, polycarbonate, polystyrene, or polyacrylate), and composite materials (e.g., CFK).

[0152] The compositions of the present invention can therefore be used as adhesives or sealants, for example in the following fields: construction, sanitation, automotive, solar technology, wind power technology, white goods, facade and window structures, electronics, and boat and shipbuilding.

[0153] Therefore, another subject of the present invention is the use of the above-described compositions of the present invention as adhesives, sealants, coatings or castings, particularly in the following fields: construction, sanitation, automobile manufacturing and repair, solar energy technology, wind power technology, white goods, facade and window structures, electronic devices, and boat and shipbuilding.

[0154] Another subject of the present invention is a substrate for bonding or joining obtained by the above method.

[0155] Example

[0156] Specific embodiments of the invention are described below, but they do not limit the scope of the invention. All tests were conducted at 23°C and 50% rF (relative humidity).

[0157] Weigh the components of the silicone compositions given in the table below in the indicated proportions, and mix them under vacuum at 2000 rpm for 20 seconds at 23°C and 50% rF on a Hauschild SpeedMixer. All values ​​for the components in all tables represent the weight parts (e.g., in grams) of the corresponding component added to the respective composition. Seal the resulting compositions airtight and store them at 23°C for 24 hours, then test them.

[0158] After curing for 7 days, the Shore A hardness was determined according to DIN ISO 7619-1 using a Bareiss Shore A hardness tester. To determine the Shore A hardness, circular specimens with a diameter of 42 mm and a thickness of 6 mm were prepared.

[0159] ISO 527 describes a method for determining elongation at break and tensile strength, as well as the preparation of the specimens required for this purpose. Measurements are performed on type 1B specimens (ISO 527-2) at a tensile speed of 200 mm / min at 23°C and 50% relative humidity. For this purpose, a 2 mm thick layer of the composition is pre-coated and cured for 7 days.

[0160] DIN ISO 34-1 describes the method for determining tear strength (WRW) and the preparation of the specimens required for this purpose. Measurements are performed on type C specimens.

[0161] To determine the skinning time, the composition to be tested was coated at a thickness of approximately 1 cm onto a surface approximately 20 cm thick. 2 Apply to the area. Ensure the surface is smooth. The coating time marks the start of the measurement. Use a PE pipette to contact the surface of the cured composition. The skinning time is reached when the PE pipette can be removed without any visible adhesion.

[0162] Viscosity was determined at 23°C using a CP25-1 cone and a distance of 0.049 mm with an MCR101 cone-plate viscometer from Anton-Paar GmbH, Austria, according to DIN EN ISO 3219. The given viscosity values ​​per 0.1 s⁻¹ are calculated. -1 The shear rate.

[0163] Table 1 below lists the abbreviations for the chemicals used. All polymers are based on linear polydimethylsiloxane (PDMS). Unless otherwise stated, all chemicals are commercially available from chemical manufacturers such as Sigma-Aldrich.

[0164] Table 1:

[0165]

[0166] Table 1: Ingredients used.

[0167] Polymers P1 and P2 are derived directly from Wacker; the synthesis of PDMS polymers with alkoxy end groups is described, for example, in US2008207938A1.

[0168] The preparation of catalysts used in the synthesis of polymers P3 to P6 is described in WO 2016 / 207156, WO 2013 / 087680 and WO 2015 / 193208.

[0169] Polymer P3

[0170] 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,ω-n-propyl-poly(dimethylsiloxane))bis(2,3-dicyclohexylguanidine) was added to the reaction mixture. The mixture was stirred at 40 °C for 5 hours. Subsequently, no gelation was detected when a few drops of tetrapropyl orthotitanate were added to the polymer sample, indicating that the reaction was complete. The resulting polymer was stable during storage and could be used without further processing.

[0171] Polymer P4

[0172] Polymer P4 was prepared similarly to polymer 3, except that linear OH-PDMS with a viscosity of 80,000 mPa·s was used instead of the polymer.

[0173] Polymer P5

[0174] Polymer P5 was prepared similarly to polymer 3, except that linear OH-PDMS with a viscosity of 50,000 mPa·s was used instead of the polymer.

[0175] Polymer P6

[0176] Polymer P6 was prepared similarly to polymer 3, except that linear OH-PDMS with a viscosity of 20000 mPa s was used instead of the polymer.

[0177] Effect of particle size on ground chalk GK

[0178] A series of one-component compositions (experiments E1 to E8) were prepared, differing only in the type of milled chalk used as a filler. All the milled chalk used was coated with stearate, and the main difference was in particle size.

[0179] Table 2 shows the basic formulations for tests E1 to E8, and Table 3 shows a detailed description of the ground chalk used. Table 4 shows all tests E1 to E8 and the corresponding measurement data.

[0180]

[0181] Table 2: Basic formulations for experiments E1 to E8.

[0182]

[0183] Table 3: Detailed description of the chalk GK used.

[0184]

[0185] Table 4: Measurement results of tests E1 to E8. This is not a reference test for the present invention. "n / m" indicates that it was not measured. "n / h" indicates that the silicone material was not cured after 7 days of curing time under standard conditions (standard climate).

[0186] The results in Table 4 show that the chalk GK of the present invention results in compositions with exceptionally good mechanical properties (particularly high tensile strength and simultaneously high elongation at break). Even more surprisingly, the compositions of the present invention exhibit exceptionally high tear strength. These properties are substantially maintained even after artificial aging. In contrast, non-inventory chalk (E7) or precipitated chalk (E8) with excessively small particle sizes, while exhibiting good tear strength in the fresh state, show absolutely insufficient storage stability and completely fail to solidify after artificial aging. In all embodiments, artificial aging was performed by storing the prepared samples in a sealed container at 70°C for 7 days. This high-temperature storage allows for the determination of the storage stability of the compositions by simulating accelerated aging.

[0187] Effect of the amount of ground chalk GK

[0188] A series of tests, E9 to E16, were conducted using milled chalk GK in different parts by weight. Detailed descriptions of these tests and the relevant measurement results are shown in Table 5. The formulation data pertains to the weight parts of each component. The components are specified in Tables 1 and 3.

[0189]

[0190] Table 5: Detailed description of the formulations and measurement results for tests E9 to E16.

[0191] Effect of chain length of polydiorganosiloxane P

[0192] A series of tests, E17 to E24, were conducted using different polymers P with varying chain lengths. Detailed descriptions of these tests and the corresponding measurement results are shown in Table 6. The formulation data pertains to the weight parts of each component. The components are specified in Tables 1 and 3.

[0193]

[0194] Table 6: Detailed formulation specifications and measurement results for tests E17 to E24. “n / m” indicates not measured. Reference tests not applicable to this invention.

[0195] The influence of polymers PE with polyether structural units

[0196] A series of tests, E25 to E30, were conducted using different PE polymers with polyether structural units. Detailed descriptions of these tests and the corresponding measurement results are shown in Table 8. The formulation data pertains to the weight parts of each component. The components are specified in Tables 1 and 7.

[0197]

[0198] Table 7: Detailed description of the polymers with polyether structural units used.

[0199]

[0200] Table 8: Detailed formulation specifications and measurement results for tests E25 to E30. “n / m” indicates no measurement, and “n / h” indicates no curing.

[0201] As can be seen from Table 8, polymers with polyether structural units can be used as additives to significantly improve storage stability, especially when the polymer is a hydroxyl-functionalized polymer or an amine-functionalized polymer.

[0202] Effects of catalyst K and acid

[0203] A series of experiments, E31 to E38, were conducted using different catalysts K or in different amounts. Detailed descriptions of these experiments and the relevant measurement results are shown in Tables 9 and 10. The formulation data pertains to the weight parts of each component. The components are specified in Tables 1 and 7.

[0204] Experiments E31 to E38 demonstrate the effect of different acid-to-catalyst K ratios on the composition properties. In each case, the acid and catalyst were added together at the end of preparation.

[0205] Experiments E39 to E46 demonstrated the effect of acid on the storage stability of tin catalysts. In some experiments, the acid was pre-reacted with the catalyst and added as a mixture. In contrast, in experiment E46, the acid was added together with the crosslinking agent. The pre-reaction of the acid with the tin catalyst could be monitored by NMR spectroscopy: 31 In ¹H NMR, the chemical shift changes when the phosphate ester is complexed with tin (from 0.25 ppm for the free monoester or 1.45 ppm for the free diester to -3.2 ppm for the phosphate ester ligand complexed with tin). 119 The same phenomenon can be observed in SN-NMR spectra: when all the tin atoms of the catalyst are complexed with the phosphate ester ligands, the chemical shift changes from -160 ppm (catalyst K1 or K3 used) to -262 ppm (ligand exchange and formation of complexes with phosphate esters).

[0206]

[0207] Table 9: Detailed formulation specifications and measurement results for tests E31 to E38. “n / m” indicates not measured.

[0208]

[0209] Table 10: Detailed formulation specifications and measurement results for tests E39 to E46. “n / m” indicates not measured. 1 Catalyst K and acid are pre-reacted and added in the form of a mixture. 2 The acid and crosslinking agent V are added together.

Claims

1. A moisture-curing silicone composition comprising: a) at least one crosslinkable polydiorganosiloxane P having an alkoxysilane end group; b) At least one condensation catalyst K; c) At least one crosslinking agent V having an alkoxysilyl group; d) At least one milled chalk GK, which constitutes at least the main part of all the included fillers; e) Optional other components, especially non-reactive polydiorganosiloxanes as plasticizers; Its features are, The particle size d50 of the ground chalk GK, as determined according to ISO 13320:2009 standard, is greater than 0.6µm and less than 2µm.

2. The moisture-curing silicone composition according to claim 1, characterized in that, The crosslinkable polydiorganosiloxane P is prepared by the condensation reaction of OH-terminated polydiorganosiloxane with a trialkoxysilane or a tetraalkoxysilane, wherein the trialkoxysilane is preferably a methyltrialkoxysilane or a vinyltrialkoxysilane.

3. The moisture-curing silicone composition according to claim 2, characterized in that, The reaction of OH-terminated polydiorganosiloxanes with trialkoxysilanes or tetraalkoxysilanes is carried out in the presence of an amidine catalyst or a guanidine catalyst.

4. The moisture-curing silicone composition according to any one of the preceding claims, characterized in that, Crosslinking agent V is an amino-containing alkoxysilane or alkoxysiloxane selected from 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane, N-(2-aminoethyl)-3-aminopropyl-methyldimethoxysilane, and oligomeric siloxanes obtained by partial condensation of at least one of these silanes and optionally other silanes.

5. The moisture-curing silicone composition according to any one of the preceding claims, characterized in that, The condensation catalyst K is a compound of an element from Group 1, 2, 4, 12, 14 or 15 of the periodic table, preferably a compound from Group 4 or 14, particularly preferably a compound of titanium or tin, and very particularly preferably an organotin compound.

6. The moisture-curing silicone composition according to any one of the preceding claims, characterized in that, Based on the entire composition, the silicone composition contains between 30% and 70% by weight, preferably between 40% and 60% by weight, and particularly between 45% and 55% by weight of ground chalk GK.

7. The moisture-curing silicone composition according to any one of the preceding claims, characterized in that, Based on the whole composition, the composition further contains between 0.1 wt% and 1.5 wt%, preferably between 0.2 wt% and 1.0 wt% of an acid or its conjugate base, preferably partially esterified phosphoric acid and / or partially esterified phosphonic acid, wherein they are preferably present in a form complexed with condensation catalyst K.

8. The moisture-curing silicone composition according to any one of the preceding claims, characterized in that, The composition further comprises a polymer PE having a polyether structural unit and preferably at least one hydroxyl and / or amino group; in particular, the amount of the polymer PE is between 0.5% and 7.5% by weight, preferably between 1% and 7% by weight, based on the whole composition.

9. The moisture-curing silicone composition according to claim 8, characterized in that, The polymer PE does not have silane groups, polydiorganosiloxane chains, and / or polyolefin chains.

10. The moisture-curing silicone composition according to any one of the preceding claims, characterized in that, The composition further comprises preferably hydrophobic pyrolytic silica; in particular, the amount of pyrolytic silica is between 1% and 10% by weight, preferably between 2% and 5% by weight, based on the whole composition.

11. The moisture-curing silicone composition according to any one of the preceding claims, characterized in that, The crosslinking agent V includes oligosiloxanes, particularly oligosiloxanes having alkoxysilyl groups and vinyl groups.

12. The moisture-curing silicone composition according to any one of the preceding claims, characterized in that, Other components include OH-terminated polydimethylsiloxane, plasticizers, tackifiers, curing accelerators, OH scavengers, desiccants, wetting agents, rheology modifiers, thixotropic agents, processing aids, biocides, UV stabilizers, heat stabilizers, flame retardants, color pigments, fragrances, antistatic agents, and / or emulsifiers.

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

14. Use of the composition according to any one of the preceding claims as an adhesive, sealant, coating or casting material, particularly in the following fields: construction, sanitation, automobile manufacturing and repair, solar energy technology, wind power technology, white goods, facade and window structures, electronic equipment, and boat and shipbuilding.

15. A method for bonding or joining substrates using a moisture-curing composition according to any one of claims 1-13, comprising: a) Optional mixing of composition components stored in different containers to obtain a complete mixture of all components of the composition. b) Applying the fully mixed composition to a substrate and bringing the mixture onto another substrate into contact to achieve an adhesive bond between the substrates, or introducing the mixture into the seam between two substrates to achieve a joint between the substrates, and c) The applied composition is cured by the action of moisture, especially air moisture.

16. A bonded or joined substrate obtained by the method according to claim 15.

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