Fast-curing two-component silicone composition having improved thermal stability

Abstract

The present invention provides a two-component silicone composition consisting of a component A comprising, based in each case on component A, 20 to 80 wt% of hydroxyl-terminated polydiorganosiloxane, 5 to 50 wt% of uncoated hydrophilic precipitated chalk, preferably between 0.05 and 5.0 wt% of water, preferably between 0.05 and 3.0 wt% of dispersion additive, and optionally further ingredients; and a component B comprising preferably at least one non-condensable polydiorganosiloxane as plasticizer, at least one organosilane as crosslinker, at least one catalyst for the crosslinking of polydiorganosiloxanes, and optionally further ingredients; characterized in that the silicone composition contains less than 5 wt%, based on the overall composition, of coated hydrophobic precipitated chalk if present. The composition according to the invention shows exceptionally good high-temperature stability.

Description

[0001] Fast-curing two-component silicone composition with improved temperature stability

[0002] Technical field

[0003] The present invention relates to the field of two-component silicone compositions.

[0004] State of the art

[0005] Two-component silicone compounds have been known for some time and are used particularly as adhesives and sealants in various applications. Two-component silicone compounds that cure at room temperature, also known as RTV-2 silicones (RTV-2: "room temperature vulcanizing, 2-part silicones"), are especially widespread.

[0006] Such a two-component silicone composition is described, for example, in EP 0 787 766 A1. To avoid impairing the storage stability of the composition described therein, or to prevent premature, unwanted curing, the main components—namely, an α,o-dihydroxypolydiorganosiloxane and a catalyst as well as a crosslinker for the crosslinking of polydiorganosiloxanes—are stored in two separate components. When applying such a composition, the two components are mixed together in a specified weight or volume ratio, whereupon crosslinking or curing of the composition occurs. The time during which the mixture remains processable and applicable before curing has progressed too far is called the pot life or open time.

[0007] A general advantage of using silicones over organic resins is their lower temperature sensitivity. In the past, considerable effort has been made to find silicone formulations with even better temperature stability. For example, silicone formulations are now known that can be used to coat frying pans. These are usually based on addition curing or are HTV silicones.

[0008] Furthermore, silicone formulations for encapsulating electronic components such as LEDs are known to offer increased temperature stability. These are also typically based on addition curing. Condensation-curing, moisture-curing silicones (RTV silicones), as described earlier, are easier to handle than HTV silicones because they do not require heating for curing. Compared to addition-curing silicones, RTV silicones have the advantage of being much more stable against moisture in the uncured state, which has a positive effect on storage stability, and they do not require expensive platinum catalysts for curing. However, RTV silicones are the least heat-resistant reactive silicone systems. In high-temperature applications, they often lose their mechanical properties after a short time, thus limiting their application.However, efforts have also been made in the field of RTV silicones to develop formulations with improved temperature stability. These are often based on acid-curing systems, which, however, limits their use on acid-sensitive and oxidizable surfaces and / or requires additional measures such as substrate pretreatments, which in turn incur costs and require an additional process step.

[0009] US 4769412, for example, describes the use of industrial carbon black and iron oxide to improve the temperature stability of moisture-curing RTV silicones.

[0010] US 5932650 describes as a further example the use of iron carboxylates to improve the temperature stability of one-component moisture-curing RTV silicones.

[0011] EP-A1-1361254 concerns the use of specific branched polysiloxanes to improve the temperature stability of moisture-curing RTV silicones. US 5352752 describes the use of polymers with at least partially fluorinated polymer units and siloxane polymer units to improve the temperature stability of moisture-curing RTV silicones.

[0012] The approaches described have the disadvantage that they either do not achieve the desired high temperature stability or are too expensive to implement on an industrial scale.

[0013] CN 113 817 438 A discloses a two-component RTV silicone composition containing nano-activated calcium carbonate in both components. However, it is not immediately and unambiguously apparent from this publication that this nano-activated calcium carbonate is an uncoated, hydrophilic precipitating chalk.

[0014] Description of the invention

[0015] The object of the present invention is therefore to provide a simple and inexpensive two-component RTV silicone composition which exhibits improved temperature stability in the cured state and which overcomes the disadvantages described above. In particular, the elastic, adhesive, and mechanical properties, especially the tensile shear strength, of the silicone formulation should be substantially retained in the cured state, even when exposed to elevated temperatures, for example, for 1000 h at > 200°C, or during aging at high temperature and humidity, for example, for 1000 h at 85°C and 85% relative humidity.

[0016] Surprisingly, it was found that two-component silicone compositions according to claim 1 solve this problem.

[0017] By using an uncoated, hydrophilic precipitating chalk as the main filler (or, depending on the embodiment, the sole filler), which is not at all obvious to a person skilled in the art, the temperature stability can be significantly increased compared to conventional silicone compositions that contain other fillers such as the much more common hydrophobized precipitating chalks.

[0018] Further aspects of the invention are the subject of further independent claims. Particularly preferred embodiments of the invention are the subject of dependent claims.

[0019] Ways to implement the invention

[0020] The present invention relates to a two-component silicone composition, consisting of a component A. Component A comprises, in each case based on component A, i) 20 to 80 wt.%, preferably 25 to 70 wt.%, in particular 30 to

[0021] 60 wt% hydroxyl-terminated polydiorganosiloxane P; ii) 5 to 50 wt%, preferably 10 to 45 wt%, in particular 15 to

[0022] 40 wt.% uncoated, hydrophilic precipitating chalk F; iii) preferably between 0.05 and 5.0 wt.% water, in particular emulsified water; iv) preferably between 0.05 and 3.0 wt.% dispersion additive D; v) and optionally further ingredients; and a component B comprising i) preferably at least one non-condensable polydiorganosiloxane

[0023] W as a plasticizer; ii) at least one organosilane V as a crosslinking agent; iii) at least one catalyst K for the crosslinking of polydiorganosiloxanes; iv) and optionally further ingredients; characterized in that the silicone composition, if present, contains less than 5% by weight, based on the total composition, of coated, hydrophobic precipitating chalk. In this document, the term "silane group" means a silane group bonded to an organic residue or to a polyorganosiloxane residue, with one to three, in particular two or three, hydrolyzable substituents on the silicon atom. Particularly common hydrolyzable substituents are alkoxy residues. These silane groups are also referred to as "alkoxysilane groups". Silane groups may also be present in partially or completely hydrolyzed form.

[0024] Organoalkoxysilanes are called "aminosilane" or "glycidoxysilane" if they have one or more amino or glycidoxy groups in addition to the silane group on the organic residue.

[0025] A "primary amino group" or "primary amine nitrogen" refers to an NH2 group or its nitrogen atom bonded to an organic residue; a "secondary amino group" or "secondary amine nitrogen" refers to an NH group or its nitrogen atom bonded to two organic residues, which may also be part of a ring; and a "tertiary amino group" or "tertiary amine nitrogen" refers to an N group or its nitrogen atom bonded to three organic residues, which may also be part of one or more rings in pairs or groups of three.

[0026] The term "organic polymer" encompasses a group of chemically uniform macromolecules that differ in degree of polymerization, molar mass, and chain length, are produced by a polymerization reaction (polymerization, polyaddition, polycondensation), and have a polymer backbone consisting predominantly of carbon atoms, as well as the reaction products of such a group of macromolecules. Polymers with a polyorganosiloxane backbone (commonly referred to as "silicones") are not considered organic polymers within the meaning of this document.

[0027] In this document, "molecular weight" refers to the molar mass (in grams per mole) of a molecule or a part of a molecule, also called the "remainder". The "mean molecular weight" is the number mean M. nan oligomeric or polymeric mixture of molecules or residues, which is usually determined by gel permeation chromatography (GPC) against polystyrene as a standard. A substance or composition is described as "storage-stable" or "storable" if it can be stored at room temperature in a suitable container for an extended period, typically at least 6 months up to 9 months or more, without its application or usage properties, in particular viscosity and crosslinking rate, changing to an extent relevant to its use.

[0028] In this document, substance names beginning with "Poly", such as polyol, refer to substances that formally contain two or more of the functional groups appearing in their name per molecule.

[0029] In this document, the term "polymer" encompasses, on the one hand, a group of chemically uniform macromolecules that differ in degree of polymerization, molar mass, and chain length, and which are produced by a polymerization reaction (polymerization, polyaddition, polycondensation). On the other hand, the term also includes derivatives of such a group of macromolecules from polymerization reactions; that is, compounds obtained by changes, such as additions or substitutions, of functional groups on given macromolecules, and which may be chemically uniform or chemically heterogeneous. Furthermore, the term also includes so-called prepolymers, that is, reactive oligomeric pre-adducts whose functional groups are involved in the construction of macromolecules.

[0030] The term "pot life" or synonymous "open time" refers to the processing time of reactive compounds after their application. In most cases, the end of the pot life is associated with such a significant increase in the viscosity of the compound that further processing is no longer possible. A dashed line in the formulas in this document represents the bond between a substituent and its corresponding molecular residue. "Room temperature" refers to a temperature of approximately 23°C.

[0031] Unless otherwise stated, all industry norms or standards mentioned in this document refer to the version of the industry norm or standard valid at the time of filing the patent application. The terms "mass" and "weight" are used synonymously in this document. Thus, a "weight percent" (wt%) refers to a percentage by mass which, unless otherwise stated, refers to the mass (weight) of the entire composition or, depending on the context, of the entire molecule.

[0032] Component A

[0033] The first component A of the two-component silicone composition contains, based on component A, i) 20 to 80 wt.%, preferably 25 to 70 wt.%, in particular 30 to 60 wt.% hydroxyl group-terminated polydiorganosiloxane P; ii) 5 to 50 wt.%, preferably 10 to 45 wt.%, in particular 15 to 40 wt.% uncoated, hydrophilic precipitating chalk F; iii) preferably between 0.05 and 5.0 wt.% water, in particular emulsified water; iv) preferably between 0.05 and 3.0 wt.% dispersion additive D; and optionally further ingredients.

[0034] Polydiorganosiloxane P

[0035] Component A of the two-component silicone composition comprises the hydroxyl group terminated polydiorganosiloxane P, which in particular is a polydiorganosiloxane P' of formula (IV).

[0036] The remaining R 1 and R 2independently of each other for linear or branched, monovalent hydrocarbon residues with 1 to 12 C atoms, which optionally have one or more heteroatoms, and optionally one or more C-C multiple bonds and / or optionally cycloaliphatic and / or aromatic parts, wherein the residues R 1 and R 2 preferably for alkyl groups with 1 to 5, in particular with 1 to 3, carbon atoms, most preferably for methyl groups; and n is chosen such that the weight mean of the molecular weight Mw of the polydiorganosiloxane P' relative to polystyrene is 500 to 250,000 g / mol, preferably 1,000 to 100,000 g / mol.

[0037] In particular, the remaining R 1 and R 2for alkyl groups with 1 to 5, in particular with 1 to 3, carbon atoms, preferably for methyl groups. The index n is chosen such that the weight average of the molecular weight Mw of the polydiorganosiloxane P relative to polystyrene is 500 to 250,000 g / mol, preferably 1,000 to 100,000 g / mol.

[0038] In particular, the hydroxyl group terminated polydiorganosiloxane P' is a polydiorganosiloxane P1 of formula (IV), wherein n is chosen such that the weight mean of the molecular weight Mw of the polydiorganosiloxane P1 relative to polystyrene is 30,000 to 80,000 g / mol, in particular 35,000 to 60,000 g / mol; or that the polydiorganosiloxane P' is a mixture of i') at least one hydroxyl group-terminated polydiorganosiloxane P2 of formula (IV), wherein n is chosen such that the weight mean of the molecular weight Mw of the polydiorganosiloxane P2 relative to polystyrene is 10,000 to 60,000 g / mol, in particular 20,000 to 55,000 g / mol, preferably 30,000 to 50,000 g / mol;and ii') at least one hydroxyl-terminated polydiorganosiloxane P3 of formula (IV), wherein n is chosen such that the weight mean of the molecular weight Mw of the polydiorganosiloxane P3 relative to polystyrene is 30,000 to 90,000 g / mol, in particular 40,000 to 80,000 g / mol, preferably 50,000 to 70,000 g / mol.

[0039] Hydroxyl-terminated polydiorganosiloxanes, such as those shown in formula (IV), are known and commercially available. The preparation of such polydiorganosiloxanes is also carried out in a known manner. For example, it is described in US 4,962,152. The hydroxyl-terminated polydiorganosiloxanes P described above preferably have a viscosity between 1 and 500,000 mPa s, and particularly between 10 and 250,000 mPa s, at 23°C.

[0040] Furthermore, the polydiorganosiloxane P1 preferably has a viscosity between 5,000 and 100,000 mPa s, in particular between 10,000 and 75,000 mPa s, at 23°C.

[0041] If the polydiorganosiloxane P' is a mixture of at least one hydroxyl-terminated polydiorganosiloxane P2 and at least one hydroxyl-terminated polydiorganosiloxane P3, then the polydiorganosiloxane P2 preferably has a viscosity between 10,000 and 50,000 mPa s, in particular between 15,000 and 25,000 mPa s, at 23°C, and the polydiorganosiloxane P3 preferably has a viscosity between 20,000 and 100,000 mPa s, in particular between 30,000 and 75,000 mPa s, preferably between 40,000 and 60,000 mPa s.

[0042] The specified viscosities are measured according to DIN 53018.

[0043] It may be advantageous to use several different polydiorganosiloxanes P2 and / or P3 as a mixture.

[0044] When polydiorganosiloxane P' is a mixture of at least one polydiorganosiloxane P2 and at least one polydiorganosiloxane P3, the weight fraction of polydiorganosiloxane P2 is generally lower than the weight fraction of polydiorganosiloxane P3. The higher the proportion of polydiorganosiloxane P3 in this mixture, the faster the composition hardens. A preferred mixture of at least one polydiorganosiloxane P2 and at least one polydiorganosiloxane P3 contains 1 to 4 parts by weight, preferably 2 to 3 parts by weight of polydiorganosiloxane P3 per part by weight of polydiorganosiloxane P2.

[0045] Component A contains the hydroxyl group-terminated polydiorganosiloxane P or the hydroxyl group-terminated polydiorganosiloxane P' preferably in an amount of between 25 wt.% and 70 wt.%, preferably between 30 wt.% and 60 wt.%, based on component A.

[0046] If the polydiorganosiloxane P' is a mixture of at least one hydroxyl-terminated polydiorganosiloxane P2 and at least one hydroxyl-terminated polydiorganosiloxane P3, then component A preferably contains between 5 wt.% and 30 wt.%, preferably between 10 wt.% and 20 wt.%, based on component A, of hydroxyl-terminated polydiorganosiloxane P2, and between 20 wt.% and 60 wt.%, preferably between 30 wt.% and 50 wt.%, based on component A, of hydroxyl-terminated polydiorganosiloxane P3.

[0047] The described polydiorganosiloxanes P can, in any embodiment, also include branches (so-called T-units) which carry Si-OH groups on side chains. However, it is preferred that the polydiorganosiloxanes are predominantly linear and without Si-OH-reactive side chains.

[0048] Water

[0049] Component A of the two-component silicone composition preferably comprises between 0.05 wt.% and 5.0 wt.% water, in particular emulsified water, based on component A. Water in component A leads to rapid, uniform curing of the mixed two-component composition and is essential to enable rapid and uniform curing according to the invention. Preferably, the amount of water is between 0.1 wt.% and 2.5 wt.%, in particular between 0.1 wt.% and 1.5 wt.%, based on component A.

[0050] Water can be added easily, especially if surfactants such as the dispersion additives D mentioned below, specifically polyethers, are present. However, separation problems could occur with larger quantities of water.

[0051] Therefore, in some preferred embodiments, the water is not present in free form or as adsorbed water (e.g., on fillers), but rather mixed in as an emulsion (for example, in silicone oil). This allows for more homogeneous mixing with lower concentration gradients and more uniform curing of the mixed composition after application. For example, water / oil emulsions with 40 to 60 wt% water, based on the emulsion, have proven advantageous.

[0052] Dispersion additive D

[0053] Component A of the two-component silicone composition preferably contains between 0.05 and 3.5 wt.%, in particular between 0.1 and 3.0 wt.%, most preferably between 0.5 and 2.5 wt.% dispersion additive D, based on component A.

[0054] Dispersion additives are commonly used in silicone formulations containing fillers and / or pigments. Also known as dispersants or wetting agents, they facilitate the incorporation of solids into a liquid or pasty matrix. In principle, all common dispersion additives are suitable for silicones, and the appropriate amount for a given formulation depends on the type of dispersion additive and the relative amount of uncoated, hydrophilic precipitated chalk (F) and other components, such as additional fillers and other particulate ingredients.

[0055] The use of dispersion additive D offers several advantages. First, it allows for the homogeneous incorporation of larger quantities of uncoated, hydrophilic precipitating chalk F, thus improving the heat resistance of the composition. Furthermore, the viscosity of the composition is not excessively increased, ensuring that it remains easily pumpable, particularly by machine, and readily applicable. The simultaneous use of dispersion additive D is especially advantageous in embodiments where component A contains water.

[0056] In preferred embodiments, the dispersion additive D is a polymeric substance with at least partial polyether content.

[0057] Preferably, polymeric substances with at least partial polyether backbones or side chains, especially with polypropylene glycol content, are used as dispersion additive D. These can be pure polyethers, for example, polyether polyols such as the Acclaim® types from Covestro. Polyether-polysiloxane copolymers are also preferred. Other dispersion additives are also suitable, provided they do not react undesirably with the ingredients of the silicone composition.

[0058] Uncoated, hydrophilic precipitating chalk F

[0059] Component A of the two-component silicone composition further comprises, based on component A, 5 to 50 wt.%, preferably 10 to 45 wt.%, in particular 15 to 40 wt.% uncoated, hydrophilic precipitating chalk F.

[0060] Precipitated chalk F is a chalk (calcium carbonate) that is synthetically produced via a precipitation reaction in an aqueous medium. This distinguishes it from ground natural chalks obtained from limestone or marble quarries.

[0061] Unlike conventional silicone compositions, the precipitating chalk F must not be surface-treated, i.e., hydrophobized, but must be untreated and therefore hydrophilic.

[0062] Surprisingly, it was found that only uncoated, hydrophilic precipitating chalk F enables the high-temperature stability effect according to the invention. Coated (hydrophobized) precipitating chalks are unsuitable and even counterproductive. Therefore, the restriction also applies that the silicone composition, if present, must contain less than 5% by weight, based on the total composition, of coated, hydrophobic precipitating chalk.

[0063] Precipitating chalks have the advantage over ground chalks that they are usually finer, more homogeneous, and chemically purer. Untreated (uncoated) hydrophilic precipitating chalks often contain a high amount of water due to the manufacturing process, which is undesirable in many silicone compositions. In the case of the present invention, however, this is irrelevant or even desirable. Therefore, precipitating chalk F does not need to be dried or otherwise prepared before use.

[0064] Suitable uncoated, hydrophilic precipitating chalks F are commercially available, for example under the trade names Schaefer Preacarb® 400 from Schaefer Kalk, or Magnum Fill SD, SDL, M and H097, as well as Calopake® F from Specialty Minerals.

[0065] Component A of the two-component silicone composition may further contain additional additives, such as further fillers, plasticizers, pigments, and formulation additives like biocides or thixotropic agents. Such additives are known to those skilled in silicone formulation. These additives can improve the processability and miscibility of component A and / or the mixed two-component silicone composition, as well as the properties of the cured compositions. However, they are not essential for the effect of the invention.

[0066] Component B

[0067] The second component B of the two-component silicone composition contains: i) preferably at least one non-condensable polydiorganosiloxane

[0068] W as a plasticizer; ii) at least one organosilane V as a crosslinking agent; iii) at least one catalyst K for the crosslinking of polydiorganosilanes; iv) and, if applicable, other ingredients.

[0069] Plasticizer W

[0070] Component B, and preferably also component A, contain in particular at least one non-condensable polydiorganosiloxane as plasticizer W. This is usually a polydiorganosiloxane whose end groups are closed with alkyl or vinyl groups and which consequently cannot undergo condensation or crosslinking reactions.

[0071] Trialkylsilyl-terminated polydialkylsiloxanes, especially trimethylsilyl-terminated polydimethylsiloxanes as described above, are particularly suitable as plasticizers. However, trimethylsilyl-terminated polydimethylsiloxanes can also be used, in which some of the methyl groups are replaced by other organic groups such as phenyl, vinyl, or trifluoropropyl. Although linear trimethylsilyl-terminated polydimethylsiloxanes are particularly preferred as plasticizers, branched compounds can also be used. Such branched compounds are formed by using small amounts of tri- or tetrafunctional silanes in the starting materials used to produce them. It is also possible to use other organic compounds, such as certain hydrocarbons, hydroxyl-free polyethers, or mixtures thereof, as plasticizers instead of polysiloxane plasticizers.Such hydrocarbons can be aromatic or aliphatic. When selecting them, it is particularly important to ensure that these hydrocarbons have low volatility and sufficient compatibility with the other components of the silicone composition.

[0072] Preferred plasticizers are polydimethylsiloxanes with viscosities between 1 and 200,000 mPa s. Viscosities between 10 and 150,000 mPa s are particularly preferred. It is especially advantageous and preferred if trialkylsilyl-terminated polydimethylsiloxanes with viscosities between 1 and 10,000 mPa s, preferably between 10 and 1,000 mPa s, are used as plasticizers in component A. This allows for particularly advantageous viscosities to be achieved for component A, which facilitates mixing.

[0073] It is particularly advantageous and preferred if trialkylsilyl-termated polydimethylsiloxanes with viscosities between 10,000 and 200,000 mPa s, preferably between 20,000 and 150,000 mPa s, are used as plasticizer W in component B. This results in particularly good storage stability and a particularly low tendency for phase separation in component B.

[0074] Such plasticizers (W) are well known to silicone formulation experts and are marketed, for example, under the trade name Wacker® AK series by Wacker Chemie, Germany, and described in more detail below. These non-reactive polydiorganosiloxanes are also known as silicone oils. They are available in various chain lengths and thus viscosities, and their primary purpose is to make solid components such as fillers easily mixable and homogenizable with the other components, as well as to improve the mechanical and flow properties of the composition.

[0075] Component B preferably contains between 10 wt.% and 60 wt.% of plasticizer W.

[0076] Component A preferably contains between 1 wt.% and 15 wt.% of plasticizer W. Component A requires less or no plasticizer W because component A already contains liquid hydroxyl group terminated polydiorganosiloxanes.

[0077] It can be advantageous to combine different such plasticizers W, for example with different viscosities or different end groups. Preferably, component B contains at least one plasticizer W with vinylsilane end groups or methylsilane end groups.

[0078] Catalyst K

[0079] Component B of the two-component silicone composition further comprises at least one catalyst K for the crosslinking of polydiorganosiloxanes.

[0080] Suitable catalysts K are commercially available. Metal catalysts, for example, are suitable as catalysts K. Metal catalysts can be compounds and complexes of elements from main groups I, II, III, and IV, as well as from transition groups I, II, IV, VI, and VII of the periodic table. Examples of preferred catalysts are organotin compounds and / or titanates or organotitanates. It is possible, and in certain cases even preferred, to use mixtures of different catalysts.

[0081] Preferred organotin compounds are dialkyltin compounds, e.g. 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 dimaleinate, di-n-butyltin dioleate, di-n-octyltin di-2-ethylhexanoate, di-n-octyltin di-2,2-dimethyloctanoate, di-n-octyltin dimaleinate, di-n-octyltin dilaurate, di-n-butyltin oxide and di-n-octyltin oxide.

[0082] 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 are preferably those selected from the group consisting of alkoxy, sulfonate, carboxylate, dialkyl phosphate, and dialkyl pyrophosphate. Tetrabutyl titanate and tetraisopropyl titanate are examples of preferred titanates. Further suitable titanates have at least one multidentate ligand, also called a chelating ligand, and optionally at least one additional ligand from the group mentioned above. The multidentate ligand is preferably a bidentate ligand. An example of a suitable chelating ligand is the acetylacetonate group.

[0083] Suitable titanates are commercially available, for example, under the trade names Tyzor® AA, GBA, GBO, AA-75, AA-65, AA-105, DC, BEAT, IBAY from Dorf Ketal or under the trade names Tytan® PBT, TET, X85, TAA, ET, S2, S4 or S6 from Borica.

[0084] In a preferred embodiment of the invention, catalyst K is a tin complex with two mercaptide ligands according to formula (V), where ligands L 1 independently of one another stand for sulfur-coordinated alkyl mercaptides, in particular Ce to C alkyl mercaptides, preferably Cs to Ci 4 alkyl mercaptides, most preferably C10 to C12 alkyl mercaptides, wherein ligands L 1 optionally include methyl dialkoxysilane groups, preferably methyl dimethoxysilane groups, and ligands L 2 independently of each other stand for Cs to Cis alkyl ligands, in particular for Cs to C14 alkyl ligands, preferably for Cs to C12 alkyl ligands.

[0085] In these embodiments, catalyst K is therefore an Sn(IV) complex with two Cs to Cis alkyl ligands L. 2 , in particular two Cs to C14 alkyl ligands L 2 .

[0086] It has been found that very short alkyl ligands, such as methyl ligands, lead to poor storage stability of component B and are therefore used as ligand L. 2 are not suitable.

[0087] Ligands L are preferred 2 Ce to C14 alkyl ligands, in particular phenyl, hexyl, octyl, or dodecyl ligands, mostly preferably octyl ligands. These form particularly storage-stable complexes and exhibit particularly good activity according to the invention in the composition.

[0088] Furthermore, in these embodiments, catalyst K has two mercaptylandes L coordinated via the sulfur atoms. 1 , in particular Ce to C alkyl mercaptides, wherein ligands L 1Optionally, they contain methyl dialkoxysilane groups, preferably methyl dimethoxysilane groups. The term mercaptide is used synonymously with the term thiolate and describes deprotonated R-S' ligands, where R is an organic residue.

[0089] It has turned out that the two ligands L 1 It is not possible to represent a single bidentate ligand with two thiolate groups, as the chelate effect may impair the inventive action. Therefore, ligands L 1 The ligands should consist of two individually coordinated alkyl mercaptide ligands. It is preferred that these ligands do not contain any further heteroatoms coordinable to tin, such as amino or carboxylate groups. Preferably, the ligands comprise L 1No functional groups with heteroatoms, except for methyldialkoxysilane groups. Methyldialkoxysilane groups, especially methyldimethoxysilane groups, can be advantageous because they can be incorporated into the polymer backbone and thereby restrict the mobility of the sulfur ligands. This has the advantage of preventing undesirable migration effects and / or any yellowing. However, it is preferred if the methylalkoxysilane groups, if present, have the same alkoxysilane groups as the crosslinking agents V.

[0090] Furthermore, it has been shown that ligands L 1 are not suitable with trialkoxysilane groups, as they impair the effectiveness of the catalyst and the storage stability of the composition.

[0091] Ligands L are preferred 1Dodecylthiolate ligands, octadecylthiolate ligands, or 3-mercaptopropyl methyldimethoxysilane ligands coordinated via the sulfur atom are suitable. Dodecylthiolate ligands are particularly preferred. These lead to a particularly effective and storage-stable catalyst K. Dodecylthiolate ligands have the further advantage of having a barely perceptible odor compared to ligands with shorter alkyl chains, yet remaining liquid at room temperature and thus easy to handle, unlike ligands with longer alkyl chains.

[0092] Furthermore, 3-mercaptopropyl methyldimethoxysilane ligands coordinated via the sulfur atom are particularly preferred.

[0093] These lead to a particularly effective catalyst K and to a particularly low tendency for the hardened composition to yellow.

[0094] In a particularly preferred embodiment of catalyst K, both ligands L are represented in formula (V). 1 for dodecyl mercaptide and both ligands L 2 for Octyl.

[0095] In a further particularly preferred embodiment of catalyst K, both ligands L are represented in formula (V). 1 for 3-mercaptopropyl-methyldimethoxysilane and both ligands L 2 for Octyl.

[0096] Such catalysts K can be easily produced, for example by combining dialkyltin diacetates with the appropriate

[0097] Mercaptan ligands are stirred together in a molar ratio of approximately 2:1 (ligand:tin complex) under exclusion of air for 24 hours at 23 °C. Byproducts formed by ligand exchange, such as acetic acid, can advantageously be removed, for example by distillation at reduced pressure.

[0098] Of course, it is possible, or in certain cases even preferred, to use mixtures of different catalysts K.

[0099] The proportion of catalyst K for the crosslinking of polydiorganosiloxanes is preferably 0.05 to 10 wt.%, particularly 0.1 to 5 wt.%, and more preferably 0.25 to 4 wt.%, based on component B of the two-component silicone composition. The amount of catalyst K influences the pot life and the adjustable pot life range of the mixed two-component composition. The higher the catalyst content, the shorter the adjustable pot life tends to be, as well as the faster the subsequent curing. However, these effects are also strongly influenced by the choice of crosslinking agents. This will be discussed further below.

[0100] Component B of the two-component silicone composition further contains at least one, preferably several different, crosslinking agents for silicone compositions. Crosslinking agents are defined as organic silicon compounds with hydrolyzable alkoxysilane groups. The present invention distinguishes three different crosslinking agent types, V1, V2, and V3, which are explained in more detail below.

[0101] It is advantageous and preferred for the effect of the present invention if all crosslinkers in the composition contain the same alkoxysilane groups. For example, all crosslinkers can contain methoxysilane groups or all crosslinkers can contain ethoxysilane groups. Mixtures of different alkoxysilane groups are usually not advantageous and can hinder or even prevent the effect of the invention.

[0102] However, mixtures of crosslinkers with methoxy and ethoxysilane groups can certainly be used, for example, if the slowest hydrolyzing crosslinker V has ethoxysilane groups instead of methoxysilane groups, and all other, faster crosslinkers V have methoxysilane groups. Even when a mixture of crosslinkers V is used, crosslinkers comprising a very small proportion of the mixture may have different alkoxysilane groups than the rest of the crosslinkers, which, however, should then be similar with respect to alkoxysilane groups. In such mixtures, the effect of the invention is not impaired. Crosslinker V1

[0103] Component B of the composition according to the invention contains, in some embodiments, between 1 and 50 wt.%, based on component B, at least one first organosilane V1 according to formula (I), where R astands for a hydrogen atom or a monovalent, linear or branched alkyl group with 1 to 6 carbon atoms,

[0104] R b stands for a divalent, linear or branched alkyl or alkenyl group with 2 to 20 carbon atoms.

[0105] R is preferred a for a hydrogen atom or a methyl or ethyl group. R is most preferred. a for a hydrogen atom or a methyl group. Silanes V1 with ethyl groups as R a , which are converted into hydrogen atoms after hydrolysis, are particularly advantageous because they allow for a particularly well-controlled pot life setting, yet harden very quickly, and also do not cause any toxic methanol emissions.

[0106] Silane V1 with methyl groups as R a, which are converted into hydrogen atoms after hydrolysis are particularly advantageous because they harden very quickly after the end of the pot life, and yet allow long pot lives and long mixer open times.

[0107] R is preferred b for a linear alkyl or alkenyl group with 2 to 12 carbon atoms, preferably with 2 to 6 carbon atoms, most preferably an ethyl group, a propyl group, an ethylene group or a propenyl group.

[0108] Organosilane V1 is not strictly necessary for the effect of the invention, but in combination with organosilane V2, it offers the advantage of allowing for better control of the pot life when present in the formulation. Using organosilane V1 allows the maximum possible pot life of the composition to be increased without significantly slowing down the curing rate after the end of the pot life. Preferred embodiments of the composition according to the invention contain between 10 wt.% and 30 wt.%, preferably between 12 wt.% and 20 wt.%, of organosilane V1, based on component B.

[0109] Networker V2

[0110] Component B of the composition according to the invention contains, in preferred embodiments, between 2 and 60 wt.%, based on component B, at least one organosilane V2 according to formula (II). where R a has the same significance as described for organosilane V1, and

[0111] R c stands for a divalent, linear or branched alkyl group with 2 to 20 carbon atoms, containing at least one secondary amino group and optionally a hydroxyl group and an ether oxygen.

[0112] Organosilane V2 preferably has a structure as described in formula (Ha), where R d represents a divalent, linear or branched alkyl group with 2 to 10 carbon atoms, optionally containing a hydroxyl group and an ether oxygen, and

[0113] R e represents a divalent, linear or branched alkyl group with 2 to 10 carbon atoms, optionally containing a secondary amino group.

[0114] Preferred embodiments of the composition according to the invention contain between 5 wt.% and 50 wt.%, preferably between 10 wt.% and 45 wt.%, of organosilane V2, based on component B.

[0115] In a preferred embodiment, the organosilane V2 is an organosilane V2a in which the residues R d and R e In formula (Ha) both represent a divalent, linear or branched alkyl group with 2 to 10 carbon atoms, in particular a propyl group.

[0116] In another particularly preferred embodiment, the organosilane V2 is an organosilane V2b, wherein the remainder R e in formula (Ha) represents a divalent, linear or branched alkyl group with 2 to 10 carbon atoms, optionally containing a secondary amino group, in particular a propyl group or a Cs alkyl group having a secondary amino group in the carbon chain, and group R da divalent, linear or branched alkyl group with 2 to 10 carbon atoms, in particular a propyl group, and additionally contains one of the two structural elements represented in formula (Hb). The NH group in formula (Hb) represents the NH group in formula (Ha), and the dashed line at the oxygen atom is bonded to the divalent, linear or branched alkyl group with 2 to 10 carbon atoms, in particular the propyl group.

[0117] Organosilanes V2a are commercially available, for example under the trade names Dynasylan® 1122 and Dynasylan® 1124 (Evonik). Dynasylan® 1124 is bis(trimethoxysilylpropyl)amine and Dynasylan® 1122 is bis(trimethoxysilylpropyl)amine.

[0118] Organosilanes V2b are easily prepared from commercially available organosilanes, for example by reacting an equimolar amount of 3-aminopropyltriethoxysilane with 3-glyxidoxypropyltriethoxysilane under exclusion of water until complete conversion of the epoxy groups.

[0119] A particularly preferred embodiment of organosilane V2b has in formula (Ha) for residue R e a divalent Cs alkyl group which has a secondary amino group in the carbon chain and represents residue R dA linear, divalent Ce alkyl group, which has an ether oxygen in the carbon chain and a hydroxyl group. This preferably possesses exclusively methoxysilane groups as alkoxysilane groups. Such an organosilane can be prepared, for example, by reacting an equimolar amount of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (e.g., Geniosil® GF 91, Wacker) with 3-glyxidoxypropyltrimethoxysilane (e.g., Geniosil® GF 80, Wacker) under exclusion of water until the epoxy groups are completely converted.

[0120] In preferred embodiments of the composition according to the invention, Organosilane V2 comprises Organosilane V2a as described above, wherein Organosilane V2a is contained in an amount of between 5 wt.% and 20 wt.% based on component B, and furthermore Organosilane V2 comprises Organosilane V2b as described above, wherein Organosilane V2b is contained in an amount of between 5 wt.% and 20 wt.% based on component B, and the composition further comprises at least one Organosilane V3 in an amount of between 2.5 wt.% and 20 wt.% based on component B, and the catalyst K is contained in component B in an amount of between 0.1 wt.% and 1.5 wt.% based on component B.

[0121] This embodiment enables a particularly suitable, sufficiently long pot life and mixer open time, a particularly rapid curing after the end of the pot life, and particularly good storage stability, especially of component B.

[0122] In preferred embodiments of the composition according to the invention, a mixture of organosilane V2a and organosilane V2b is used as organosilane V2. In these embodiments, the catalyst K content is preferably between 0.1 wt.% and 2 wt.%, particularly between 0.2 wt.% and 1 wt.%, based on component B. This enables a very precisely adjustable, user-friendly, yet short to medium pot life and very rapid curing, and is particularly suitable for automated, machine-based applications with short cycle times, as well as for a freely selectable pot life by means of different mixing ratios of components A and B. This is particularly advantageous for flexible applications or in complex applications where a varying pot life but consistently identical final properties of the cured composition are desired.

[0123] In this embodiment, the organosilanes V2a and V2b are preferably used in the formulation in a weight ratio of between 1:2 and 2:1. Preferred embodiments of this embodiment of the composition according to the invention contain between 5 wt.% and 25 wt.%, preferably between 7.5 wt.% and 22.5 wt.%, of organosilane V2a, based on component B, and between 0 wt.% and 25 wt.%, preferably between 5 wt.% and 22.5 wt.%, of organosilane V2b, based on component B.

[0124] Networker V3

[0125] Component B of the two-component silicone composition further preferably comprises between 0 and 25 wt.%, based on component B, additional organosilanes V3 with hydrolyzable alkoxysilane groups Si-OR a , which do not fall under formulas (I) and (II). These also serve as networkers, but are optional.

[0126] The additional organosilane V3 is in particular a silane of formula (III).

[0127] The rest R 3 Each term represents, independently of the others, a linear or branched, monovalent hydrocarbon residue with 1 to 12 carbon atoms, which may contain one or more heteroatoms, and may contain one or more CC multiple bonds and / or may contain cycloaliphatic and / or aromatic components.

[0128] The rest R 4 stands for a remainder R a as described above.

[0129] The index p represents a value from 0 to 4, with the stipulation that if p represents a value of 3 or 4, there must be at least p-2 remainders R. 3 Each compound has at least one group that is reactive with the hydroxyl groups of the polydiorganosiloxane P, in particular a condensable group, i.e., for example, a hydroxyl group. In particular, p represents a value of 0, 1, or 2, preferably a value of 0.

[0130] The choice of silane of formula (III) as a crosslinker for polydiorganosiloxanes can be determined by various requirements for the two-component silicone composition. On the one hand, the reactivity of the silane plays an important role; on the other hand, toxicological reasons can also be decisive for the choice of crosslinker.

[0131] Examples of suitable silanes of formula (III) are vinyltrimethoxysilane, methyltrimethoxysilane, chloromethyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, octyltrimetoxysilane, vinyltriethoxysilane, methyltriethoxysilane, phenyltriethoxysilane, methyltripropoxysilane, phenyltripropoxysilane, octyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane or tetra-n-butoxysilane.

[0132] Particularly preferably the silane of formula (III) is methyltrimethoxysilane, dimethyltrimethoxysilane or tetramethoxysilane or a mixture thereof, most preferably methyltrimethoxysilane, octyltrimethoxysilane, or mixtures thereof.

[0133] Furthermore, the silanes contained in component B can also already be partially (a portion of all R 4 = H) or completely hydrolyzed (all R 4= H). Due to the significantly increased reactivity of partially or fully hydrolyzed silanes, their use as crosslinking agents can be advantageous. It is known to those skilled in the art that the use of partially or fully hydrolyzed silanes can lead to the formation of oligomeric siloxanes, in particular dimers and / or trimers, which are formed by the condensation of hydrolyzed silanes. Therefore, oligomeric siloxanes can also be used as crosslinking agents for the two-component silicone composition. Suitable oligomeric siloxanes include, for example, hexamethoxydisiloxane, hexaethoxydisiloxane, hexa-n-propoxydisiloxane, hexa-n-butoxydisiloxane, octamethoxytrisiloxane, octaethoxytrisiloxane, octa-n-butoxytrisiloxane, decamethoxytetrasiloxane, and decaethoxytetrasiloxane.

[0134] Accordingly, in preferred embodiments, component B also contains oligomeric siloxanes formed by the condensation of silanes of formula (III). Such siloxanes may also be present in component A in small amounts, as long as they do not cause premature crosslinking.

[0135] Of course, any mixture of the aforementioned silanes can also be used as a crosslinker for the two-component silicone composition.

[0136] The proportion of organosilane V3 is preferably 0.1 to 25 wt.%, in particular 0.5 to 20 wt.%, preferably 1 to 15 wt.%, based on component B of the two-component silicone composition.

[0137] The two-component silicone composition may contain further components in one or both of components A and B. Such additional components include, in particular, plasticizers W as described above, which are mandatory in component B, inorganic and / or organic fillers, curing accelerators, pigments, adhesion promoters, processing aids, rheology modifiers, stabilizers, colorants, inhibitors, heat stabilizers, antistatic agents, flame retardants, biocides, waxes, leveling agents, thixotropic agents, and other common raw materials and additives known to those skilled in the art.

[0138] When using such optional components, it is important to ensure that components which could impair the storage stability of the composition through reaction with each other or with other ingredients are stored separately.

[0139] Furthermore, it is advantageous to select all the aforementioned components, which may be present in the two-component silicone composition, in such a way that the storage stability of the two components is not negatively affected by their presence. This means that the composition's properties, particularly its application and curing properties, should not change, or should change only minimally, during storage. This requires that reactions leading to the chemical curing of the described two-component silicone composition do not occur to a significant extent during storage. It is therefore particularly advantageous that the aforementioned components contain no water, or at most only trace amounts, or release no water during storage. For this reason, it may be advisable to dry certain components chemically or physically before mixing them into the composition.

[0140] Preferably, the composition further comprises at least one additional filler (besides precipitating chalk F) in one or both components A and B. The filler can influence both the rheological properties of the uncured composition and the mechanical properties and surface finish of the cured composition. Both active and passive fillers can be used in the two-component silicone composition. With active fillers, chemical or physical interactions with the polymer occur, while with passive fillers, these interactions do not occur or occur only to a minor extent.

[0141] Suitable fillers are inorganic and organic fillers, for example natural, ground or precipitated calcium carbonates, which may be coated with fatty acids, in particular stearic acid, or with preferably hydrophobic silanes or siloxanes, calcined kaolins, aluminum oxides, aluminum hydroxides, silicas, in particular highly dispersed silicas from pyrolysis processes, carbon black, in particular industrially produced carbon black, aluminum silicates, magnesium aluminum silicates, zirconium silicates, quartz flour, cristobalite flour, diatomaceous earth, mica, iron oxides, titanium oxides, zirconium oxides, gypsum, annalin, barium sulfate (BaSO4, also called barite or barite), boron carbide, boron nitride, graphite, carbon fibers, glass fibers or hollow glass spheres, the surface of which may be treated with a hydrophobizing agent.Preferred fillers are calcium carbonates, calcined kaolins, carbon black, highly dispersed silicas and flame-retardant fillers such as hydroxides or hydrates, in particular hydroxides or hydrates of aluminium, preferably aluminium hydroxide.

[0142] In a preferred embodiment, the silicone composition contains highly dispersed silicas from pyrolysis processes or precipitated and / or ground calcium carbonates, in particular hydrophobically coated, as an additional filler.

[0143] Component A preferably contains at least one filler, in particular ground, preferably hydrophobically coated, calcium carbonates.

[0144] Component B preferably contains highly dispersed silicas from pyrolysis processes and / or carbon black. However, Component B preferably does not contain uncoated, hydrophilic precipitated chalk F, as this often contains significant amounts of water due to its manufacturing process, as described above. Such moist components can have a very detrimental effect on the storage stability of Component B, since this component contains catalyst K and water-reactive organosilanes V.

[0145] It is entirely possible, and can even be advantageous, to use a mixture of different fillers.

[0146] A suitable amount of filler is, for example, in the range of 10 to 70 wt.%, in particular 15 to 60 wt.%, preferably 30 to 60 wt.%, based on the total two-component silicone composition.

[0147] However, it must be ensured that the silicone composition, if present, contains less than 5% by weight, based on the total composition, of coated, hydrophobic precipitating chalk.

[0148] Preferably, the composition contains less than 1% by weight, based on the total composition, and in particular no coated, hydrophobic precipitating chalk at all. Alkoxysilanes, preferably substituted with functional groups, are particularly suitable as adhesion promoters. The functional group is, for example, an aminopropyl, glycidoxypropyl, or mercaptopropyl group. Amino functional groups are preferred. Some of these adhesion promoters already fall under the definition of crosslinker V3 and must therefore be considered in this respect. The alkoxy groups of such silanes are usually methoxy or ethoxy groups. Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)-aminopropyltriethoxysilane, and 3-mercaptopropyltriethoxysilane are particularly preferred. It is also possible to use a mixture of adhesion promoters.Furthermore, suitable adhesion promoters include, for example, amino-functional alkyl silsesquioxanes such as amino-functional methylsilsesquioxane or amino-functional propylsilsesquioxane, alkoxylated alkyleneamines, in particular ethoxylated and / or propoxylated alkylenediamines, as well as other, in particular substituted, oligomers, polymers or copolymers based on polyalkylene glycols.

[0149] However, the composition must contain less than 10 mol%, based on the amount of organosilane V2, of organosilanes with epoxy groups or glycidoxy groups. Preferably, the composition contains less than 5 mol%, and in particular less than 1 mol%, based on the amount of organosilane V2, of organosilanes with epoxy groups. The presence of organosilanes with epoxy groups in amounts exceeding these values ​​can significantly impair the inventive effect and prevent the composition from curing properly.

[0150] It is clear to those skilled in the art that when silanes are used as adhesion promoters, they may be partially or completely hydrolyzed depending on the conditions, such as humidity. Furthermore, it is known to those skilled in the art that in the presence of such partially or completely hydrolyzed silanes, condensation reactions can lead to the formation of oligomeric siloxanes, in particular dimers and / or trimers. The proportion of the adhesion promoter, which preferably does not fall under the definition of crosslinker V3 or V2b, is preferably 0.1 to 15 wt.%, in particular 1 to 10 wt.%, and more preferably 1 to 5 wt.%, of the total two-component silicone composition. In preferred embodiments, particularly when using organosilanes V2 and / or crosslinkers V3, which can exhibit adhesion-promoting properties, the composition preferably contains no further adhesion promoters.

[0151] Experts are well aware that components such as those listed above cannot have only a single, attributed function or effect. Rather, it is common for a single component or compound to have multiple functions. For example, some adhesion promoters are also crosslinkers, and some fillers are simultaneously rheology modifiers or the like.

[0152] For example, organosilanes V2, and especially V2b, as well as certain crosslinkers V3, exhibit good adhesion-promoting properties.

[0153] In preferred embodiments, the further ingredients in component A and / or component B are selected from non-reactive polydiorganosiloxanes, further fillers, pigments, stabilizers, rheology additives, and biocides.

[0154] The two-component silicone composition according to the invention is typically stored in packaging having two separate chambers. Component A is located in one chamber and component B is located in the other chamber of the packaging. Suitable packaging includes, for example, dual cartridges such as twin or coaxial cartridges, or multi-chamber pouches with an adapter. Preferably, the two components A and B are mixed using a static mixer, which can be attached to the two-chamber packaging. Such suitable packaging is described, for example, in

[0155] US 2006 / 0155045 A1 , WO 2007 / 096355 A1 and in US 2003 / 0051610 A1 .

[0156] In a large-scale industrial plant, the two components A and B are typically stored separately in drums or pails and, during application, for example using gear pumps, pressed out and mixed. The mixture can then be applied to a substrate manually or in an automated process using a robot.

[0157] In particular, the two-component silicone composition according to the invention is used such that the weight ratio of component A to component B is > 1 : 1, in particular from 2:1 to 20: 1, preferably from 3: 1 to 16: 1.

[0158] One advantage of using components A and B in the described, preferred weight ratio is that existing systems for conveying and applying two-component silicone compositions are very widespread in this way, and converting the systems to apply components A and B in a weight ratio of, for example, 1:1 would involve considerable effort on the consumer side.

[0159] In the same or other preferred embodiments, the mixing ratio is controlled or determined via the volume of components A and B. This is particularly practical and advantageous in automated applications with individual pumping of the two components and feeding to a static or dynamic mixer. In such cases, the volume mixing ratio of component A to component B is preferably > 1:1, in particular from 1.5:1 to 20:1, and preferably from 2:1 to 16:1.

[0160] In automated pumping and mixing, it is advantageous in some embodiments if the volume fractions of components A and B do not differ excessively in order to ensure the most homogeneous mixture possible. In some such embodiments, the volume mixing ratio of component A to component B is preferably from 1.1:1 to 5:1, particularly from 1.5:1 to 3:1, and most preferably from 1.8:1 to 2.5:1.

[0161] Furthermore, component B preferably does not contain crosslinkable polydiorganosiloxanes. The advantage of this is improved storage stability of component B.

[0162] In particular, component B of the previously described two-component silicone composition is manufactured and stored in the absence of moisture. Separately, the two components are stable for storage, meaning they can be stored in suitable packaging or arrangement, as previously described, for several months up to a year or longer, without any significant change in their application properties or their post-curing properties. Storage stability is typically determined by measuring viscosity or reactivity over time.

[0163] During the application of the two-component silicone composition, components A and B are mixed together, for example by stirring, kneading, rolling, or the like, but especially using a static mixer. In this process, the hydroxyl groups of the hydroxyl-terminated polydiorganosiloxane P come into contact with the hydrolyzable or, optionally, already hydrolyzed groups of the crosslinker, resulting in the curing of the composition through condensation reactions. Contact of the silicone composition with water, particularly contact of water, which is preferably contained in component A, with the crosslinkers V, during application can also promote crosslinking, since the reaction of the water with the hydrolyzable groups of the crosslinker forms silanol groups whose reactivity towards the hydroxyl groups of the polydiorganosiloxane P is increased.The two-component silicone composition cures particularly well at room temperature.

[0164] During the crosslinking of the two-component silicone composition, compounds of the formula HO-R are formed as reaction products of the condensation reaction. a , where R a as previously described. These byproducts of the condensation reaction are preferably compounds that do not affect either the composition or the substrate to which the composition is applied. Most preferably, the reaction product is of the formula HO-R a a compound that easily evaporates from the crosslinking or already crosslinked composition.

[0165] Furthermore, the invention relates to a hardened silicone composition such as that obtained from a previously described two-component silicone composition by mixing component A with component B.

[0166] The invention further relates to the use of two-component silicone compositions, as described above, as an adhesive, sealant, coating, or casting compound. The composition according to the invention is preferably used as an adhesive.

[0167] The two-component silicone composition according to the invention is preferably used as an adhesive, sealant, coating or casting compound, in particular for the manufacture or repair of facades, fire protection joints, windows, insulating glass, solar systems, automobiles, trains, buses, ships, white, brown and red goods, electronic components or sanitary installations or for construction, especially preferably for vehicle parts from the engine or exhaust area, ovens, microwaves, irons, radio receivers, radiators and water installations.

[0168] The two-component silicone composition is particularly preferred as an adhesive in industrial manufacturing. In particular, it is used for high-temperature applications where the cured silicone composition is exposed to temperatures exceeding 150°C, and especially 200°C, at least temporarily or continuously. "Continuously" here means at least 500 hours, and in particular at least 1000 hours.

[0169] The two-component silicone composition according to the invention is used in particular in a process for bonding two substrates S1 and S2 comprising the steps a) application of a two-component silicone composition according to the preceding description onto a substrate S1 and / or a substrate S2; b) contacting the substrates S1 and S2 via the applied composition within the open time of the composition; c) curing of the composition by reaction of components A and B; wherein the substrates S1 and S2 are the same or different from each other.

[0170] Preferably, the composition according to the invention is also used in a sealing or coating process comprising the steps a') application of a two-component silicone composition according to the preceding description onto a substrate S1 and / or between two substrates S1 and S2; b') curing of the composition by reaction of components A and B; wherein the substrates S1 and S2 are the same or different from each other.

[0171] It is self-evident to those skilled in the art that the two components A and B must be mixed together immediately before or during application of the two-component composition. The two-component silicone composition according to the invention preferably has a pasty consistency with shear-thinning properties. Such a composition is applied to the substrate using a suitable device, preferably in the form of a bead, which advantageously has a substantially round or triangular cross-sectional area. A composition according to the invention with good application properties exhibits high stability and minimal stringing. That is, after application, it remains in the applied shape, i.e., it does not run apart, and after the application device is removed, it leaves no or only a very short string, so that the substrate is not contaminated.

[0172] Suitable substrates as S1 and / or S2 are, in particular, those selected from the group consisting of concrete, mortar, brick, ceramic, gypsum, natural stone such as granite or marble, glass, glass ceramic, metal or metal alloy such as aluminium, steel, non-ferrous metal, galvanized metal, wood, plastic such as PVC, polyethylene, polyamide, polymethyl (meth)acrylate, polyester, epoxy resin, paint and varnish.

[0173] The two-component silicone composition is used particularly in industrial manufacturing, especially of vehicles and everyday consumer goods, as well as in construction, especially in civil engineering and building construction.

[0174] The two-component silicone composition is preferably used in window construction and facade construction, especially in facade construction.

[0175] Furthermore, the invention relates to an article comprising an at least partially cured silicone composition according to the preceding description, wherein this article is in particular a structure, an industrial good or a means of transport, in particular a building, or a part thereof.

[0176] An exemplary list of such articles includes houses, glass facades, windows, bathrooms, kitchens, roofs, bridges, tunnels, roads, automobiles, trucks, rail vehicles, buses, ships, mirrors, panes, bathtubs, white goods, household appliances, dishwashers, washing machines, ovens, headlights, fog lights, or solar panels. Furthermore, the present invention relates to a method for adjusting the pot life while maintaining consistent mechanical properties after curing of a two-component silicone composition as described above, characterized in that the mixing ratio of component A to component B by weight is arbitrarily selected within the range of 1:1 to 25:1, in particular from 2:1 to 20:1, preferably from 3:1 to 16:1.

[0177] This method makes it particularly possible to adjust the pot life of a two-component silicone composition according to the invention within wide limits solely by changing the mixing ratio of the two components A and B. After the set pot life has elapsed, the composition cures exceptionally quickly and very uniformly. Regardless of the chosen mixing ratio, the final properties, especially the mechanical properties, of the cured composition are largely the same. This is extremely advantageous and allows a user to set and vary a flexible yet very precisely controllable pot life without having to exchange components A and B of the composition, simply by adjusting the mixing ratio, e.g., by changing the delivery rate of a pump.

[0178] This means that cycle times can be optimized even under varying process conditions without having to change the silicone material.

[0179] The composition according to the invention cures exceptionally quickly after the end of the pot life. In preferred embodiments of the silicone composition according to the invention, the ratio of pot life to tack-free time (time until the surface of the applied silicone composition has become tack-free due to advanced curing) is < 2.5, in particular between 1.1 and 2.3, preferably between 1.2 and 2.1. This enables a very efficient process control, since the composition cures extremely quickly after application and the substrate on which the composition has been applied can be immediately processed further or transported.

[0180] In contrast, prior art two-component silicone compounds typically exhibit either a very long pot life and a very long curing time, or very rapid curing but an extremely short, user-unfriendly pot life. The present invention allows for the setting of long or short pot lives as needed; however, it always allows for very rapid curing after application.

[0181] Examples

[0182] The following are exemplary embodiments intended to further illustrate the described invention. Of course, the invention is not limited to these described embodiments.

[0183] Production of silicone compounds

[0184] The following compositions were produced:

[0185] Components A and B, as listed in Tables 1 and 2, were mixed and stirred together in the specified weight percent in a dissolver at room temperature under an inert atmosphere until a macroscopically homogeneous paste was obtained.

[0186] The manufactured components A and B were sealed airtight in separate containers. During application, components A and B were mixed in a weight ratio of A : B = 3 : 1 using a speed mixer (Hauschild & Co. KG, Germany).

[0187] Description of the test methods

[0188] The tensile shear strength was measured according to DIN EN 1465 at a measuring speed of 20 mm / min on a Zwick / Roell Z005 tensile testing machine on films with a thickness of 2 mm, which had been stored for 24 hours at 23°C and 50% relative humidity (RH) prior to measurement. The values ​​given are the mean values ​​of three measurements. Some samples were stored under various high-temperature or warm-humid conditions prior to this measurement to investigate the influence of heat on the samples. The storage conditions of the respective samples are given in Table 3. However, prior to measurement, the samples were tempered for 24 hours at 23°C and 50% RH.

[0189] The Shore A hardness was determined according to DIN 53505 after storage of the hardened composition at 23°C and 50% relative humidity for 7 days, or as specified in Table 4. Prior to measurement, however, the high-temperature samples were tempered for 24 hours at 23°C and 50% relative humidity.

[0190] The method for determining the elongation at break and the preparation of the required test specimens is described in ISO 527. Measurements were taken at 23°C and 50% relative humidity on a Type 1B test specimen (ISO 527-2) at a tensile speed of 200 mm / min. For the determination of the elongation at break, some specimens were pre-treated with heat (listed in Table 3). However, prior to measurement, the specimens were tempered for 24 hours at 23°C and 50% relative humidity.

[0191] Adhesion of the coating to glass was qualitatively determined by applying a bead of the mixed composition under test to a degreased glass substrate and curing it for 7 days at 23°C and 50% relative humidity. Some samples underwent storage for 1000 hours at 225°C followed by tempering for 24 hours at 23°C and 50% relative humidity.

[0192] The evaluation was qualitative, performed by peeling the hardened adhesive bead from the glass substrate. It was then assessed whether the fracture pattern was cohesive (desired) or adhesive (undesired failure of the bond).

[0193] Production of crosslinker V2b

[0194] N-(2-Aminoethyl)-3-aminopropyltriethoxysilane (Geniosil® GF 94, Wacker) was mixed with an equimolar amount of 3-glycidoxypropyltriethoxysilane (Geniosil® GPTE, Wacker) in a glass vessel under a nitrogen atmosphere. The vessel was sealed and incubated at 23 °C for 7 days. The resulting mixture, which was free of detectable epoxy groups, was used as organosilane V2b without further processing.

[0195] Table 1: Two-component silicone compositions C1 to C3. All numbers in

[0196] wt.%, based on the respective component A or B; a OH-term. PDMS: OH-terminated polydimethylsiloxane; b Wacker Polymer AK 100: Trialkylsilane-terminated polydimethylsiloxane with a viscosity according to DIN 53018 of 100 mPa s; c Wacker Vinyl Polymer 20'000: Vinylsilane-terminated polydimethylsiloxane with a viscosity according to DIN 53018 of 20'000 mPa s.

[0197]

[0198] Table 2: Two-component silicone compositions C4 to C6. All figures in

[0199] wt.%, based on the respective component A or B; a OH-term. PDMS: OH-terminated polydimethylsiloxane; b Wacker Polymer AK 100: Trialkylsilane-terminated polydimethylsiloxane with a viscosity according to DIN 53018 of 100 mPa s; c Wacker Vinyl Polymer 20'000: Vinylsilane-terminated polydimethylsiloxane with a viscosity according to DIN 53018 of 20'000 mPa s.

[0200]

[0201] Table 3: Test data (mechanics) of the compositions C1 to C6.

[0202] All measurements were taken at 23°C / 50% rh after the respective treatment, n / m: data were not measured.

[0203] Table 4: Test data (Shore A and adhesion) of the compositions C1 and C2.

[0204] All measurements were taken at 23°C / 50% rh after the respective treatment.

Claims

Patent claims 1. Two-component silicone composition comprising a component A comprising, in each case based on component A, i) 20 to 80 wt.%, preferably 25 to 70 wt.%, in particular 30 to 60 wt% hydroxyl-terminated polydiorganosiloxane P; ii) 5 to 50 wt%, preferably 10 to 45 wt%, in particular 15 to 40 wt.% uncoated, hydrophilic precipitating chalk F; iii) preferably between 0.05 and 5.0 wt.% water, in particular emulsified water; iv) preferably between 0.05 and 3.0 wt.% dispersion additive D; v) and optionally further ingredients; and a component B comprising i) preferably at least one non-condensable polydiorganosiloxane W as a plasticizer; ii) at least one organosilane V as a crosslinker; iii) at least one catalyst K for the crosslinking of polydiorganosilanes; iv) and optionally further ingredients; characterized in that the silicone composition, if present, contains less than 5 wt.%, based on the total composition, coated, hydrophobic precipitating chalk.

2. Two-component silicone composition according to claim 1, characterized in that the hydroxyl group-terminated polydiorganosiloxane P is a polydiorganosiloxane P' of formula (IV) where the remainders R 1 and R 2 independently of one another, linear or branched monovalent hydrocarbon residues with 1 to 12 carbon atoms, which may optionally contain one or more heteroatoms, and optionally one or more C-C multiple bonds and / or optionally cycloaliphatic and / or aromatic parts, wherein the residues R 1and R 2 preferably for alkyl groups with 1 to 5, in particular with 1 to 3, carbon atoms, most preferably for methyl groups; and n is chosen such that the weight mean of the molecular weight Mw of the polydiorganosiloxane P', determined by gel permeation chromatography relative to polystyrene, is 500 to 250,000 g / mol, preferably 1,000 to 100,000 g / mol.

3. Two-component silicone composition according to one of the claims 1 or 2, characterized in that the composition contains no coated, hydrophobic precipitating chalk.

4. Two-component silicone composition according to one of the preceding claims, characterized in that the further ingredients in component A and / or component B are selected from non-reactive polydiorganosiloxanes, further fillers, pigments, stabilizers, rheology additives, and biocides.

5. Two-component silicone composition according to one of the preceding claims, characterized in that organosilane V comprises between 1 and 50 wt.%, based on component B, of at least one first organosilane V1 according to formula (I); and / or between 2 and 60 wt%, based on component B, comprising at least one second organosilane V2 according to formula (II); and up to 25 wt%, based on component B, further organosilanes V3 with hydrolyzable alkoxysilane groups Si-OR a , which do not fall under formulas (I) and (II); where R a stands for a hydrogen atom or an ethyl group or a methyl group, in particular a methyl group; R b stands for a divalent, linear or branched alkyl or alkenyl group with 2 to 20 carbon atoms, and R crepresents a divalent, linear or branched alkyl group with 2 to 20 carbon atoms, containing at least one secondary amino group; provided that the composition contains less than 10 mol%, based on the amount of organosilane V2, of organosilanes with epoxy groups.

6. Two-component silicone composition according to claim 5, characterized in that organosilane V3 comprises at least one silane of formula (III), ( 'R 3 •)— p Si- ( 'OR 4 >) 4-p ( v III) ' where the remainder R 3 independently of each other, a linear or branched, monovalent hydrocarbon residue with 1 to 12 carbon atoms, which may optionally contain one or more heteroatoms, and optionally one or more C-C multiple bonds and / or optionally cycloaliphatic and / or aromatic components; the residue R 4 for a remainder R astands; and p stands for a value from 0 to 4, with the proviso that if p stands for a value of 3 or 4, at least p-2 remainders R 3 each have at least one group that is reactive, in particular condensable, with the hydroxyl groups of the polydiorganosiloxane P.

7. Two-component silicone composition according to claim 6, characterized in that component B further comprises oligomeric siloxanes formed from the condensation of silanes of formula (III).

8. Two-component silicone composition according to one of claims 5 to 7, characterized in that the organosilane V2 comprises at least one organosilane according to formula (Ha), where R d represents a divalent, linear or branched alkyl group with 2 to 10 carbon atoms, optionally containing a hydroxyl group and an ether oxygen, and R erepresents a divalent, linear or branched alkyl group with 2 to 10 carbon atoms, optionally containing a secondary amino group.

9. Two-component silicone composition according to claim 8, characterized in that the organosilane V2 either - represents an organosilane V2a in which the residues R d and R e In formula (Ha) both represent a divalent, linear or branched alkyl group with 2 to 10 carbon atoms, in particular a propyl group; or - represents an organosilane V2b, in which the remainder R e In formula (Ha) stands for a divalent, linear or branched alkyl group with 2 to 10 carbon atoms, optionally containing a secondary amino group, and group R d a divalent, linear or branched alkyl group with 2 to 10 carbon atoms, in particular a propyl group, and additionally contains one of the two structural elements represented in formula (Hb); - or represent a mixture of an organosilane V2a and an organosilane V2b, wherein the organosilanes V2a and V2b are preferably contained in component B in a weight ratio of between 1 :2 and 2:

1.

10. Two-component silicone composition according to claim 9, characterized in that Organosilane V2 comprises Organosilane V2a, wherein Organosilane V2a is contained in an amount of between 5 wt.% and 20 wt.% based on component B, and Organosilane V2 comprises Organosilane V2b, wherein Organosilane V2b is contained in an amount of between 5 wt.% and 20 wt.% based on component B, and that at least one Organosilane V3 is contained in an amount of between 2.5 wt.% and 20 wt.% based on component B, and that the catalyst K is contained in component B in an amount of between 0.1 wt.% and 1.5 wt.% based on component B.

11. Two-component silicone composition according to one of the claims 9 or 10, characterized in that organosilane V2b has a residue R e represents a divalent Cs alkyl group which has a secondary amino group in the carbon chain and group R d represents a linear, divalent Ce alkyl group which has an ether oxygen in the carbon chain and a hydroxyl group.

12. Two-component silicone composition according to one of the preceding claims, characterized in that the weight ratio of component A to component B is > 1 :1, in particular from 1.5:1 to 20:1, preferably from 2:1 to 16:

1.

13. Two-component silicone composition according to one of the preceding claims, characterized in that the dispersion additive D is a polymeric substance with at least partial polyether content.

14. Use of a two-component silicone composition according to any one of claims 1 to 13 as an adhesive, sealant, coating or casting compound, in particular for the manufacture or repair of facades, fire protection joints, windows, insulating glass, solar systems, automobiles, trains, buses, ships, white, brown and red goods, electronic components or sanitary installations or for construction, particularly preferably for vehicle parts from the engine or exhaust area, ovens, microwaves, irons, radio receivers, radiators and water installations.

15. Use according to claim 14, characterized in that the two-component silicone composition is used as an adhesive in industrial manufacturing.

16. Use according to claim 14 or 15 for High-temperature applications where the cured silicone composition is exposed to temperatures above 150°C, and especially above 200°C, at least temporarily or permanently.

17. Cured silicone composition, characterized in that it is obtainable from a two-component silicone composition according to any one of claims 1 to 13 by mixing component A with component B.

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