WO2017162811A1

WO2017162811A1 - Curable compositions based on alkoxysilane groups-containing prepolymers

Info

Publication number: WO2017162811A1
Application number: PCT/EP2017/056963
Authority: WO
Inventors: Jürgen Köcher; Thomas Klimmasch; Thomas FULSCHE
Original assignee: Covestro Deutschland Ag
Priority date: 2016-03-23
Filing date: 2017-03-23
Publication date: 2017-09-28

Abstract

The present invention relates to curable compositions containing at least one silane-functional prepolymer with at least one alkoxysilane group and at least one compound with at least one hydrogen-polyfluoride anion. The compositions can be used as coatings, sealants and adhesives.

Description

Curable compositions based on alkoxysilane-containing prepolymers

The present invention relates to curable compositions based on alkoxysilane group-containing prepolymers, a new class of catalysts for the crosslinking of alkoxy silane-containing prepolymers, and coatings, sealants and adhesives containing silane-functional prepolymers with alkoxysilane, preferably ethoxysilane, and said catalysts for curing.

Compositions based on silane-functional polymers (in particular silane-terminated prepolymers or STPs) and their use as adhesives, sealants and coatings have been known for some time. The crosslinking mechanism of these silanes occurs through a two-step process: First, an ambient alkoxysilane hydrolyzing an alkoxysilane group into a hydroxysilane group. This hydroxysilane group may condense in a second step with an alkoxysilane group or a second hydroxysilane group. After complete hydrolysis, a network of siloxane groups is formed.

As silane-functional polymers thereby polymers are used, which are provided with different moisture-reactive silane groups. See, for example, F.D. Osterholtz and E.R. Pohl, J. Adhesion Sci. Technol. Vol 6, No 1, pages 127-149 (1992) and the publications WO 2013/174940, DE 10 2005 045 228 and EP 2 813 528.

A "silane group" is understood as meaning a chemical group which comprises a silicon atom which on the one hand has at least one covalent silicon-carbon bond and which, on the other hand, is not linked via an oxygen atom to another silicon atom.

Groups containing at least two silicon atoms which are linked together via an oxygen atom, i. contain a (Si-O-Si) structural fragment are siloxane groups.

An essential criterion for the selection of the alkoxysilane groups is the reactivity of these groups, because due to the reactivity of these silane groups, the curing rate of the

Composition is significantly influenced.

Technically available are methoxy and ethoxysilanes. In particular, the methoxysilanes are used for the preparation and use of silane-functional polymers, in particular silane-terminated prepolymers, as a coating or adhesive.

There are several possibilities for the synthesis of polyurethane-based, silane-functional polymers, in particular of polyurethane-based, silane-terminated prepolymers

Alkoxysilane via an isoeyanatreaktive group as a functional group, such as hydroxy, amino or mercapto, to an isocyanate-containing polyurethane (pre) polym er he be bound. Alternatively, an isocyanate-functional alkoxysilane can be bound to a polymer which has an iso cyanate-reactive group such as hydroxy, amino or m capto carries. Another possibility for the preparation of silane-terminated (pre) polymers is the hydrosilylation of double bonds.

In addition, there are other possibilities for the production of alkoxysilane-containing prepolymers. Thus, it is also possible to react polymeric polyisocyanates, which are prepared by oligomerization of monomeric diisocyanates, with an alkoxysilane containing an isocyanate-reactive group.

Alkoxysilane-containing prepolymers can also be obtained by polymerization of epoxides, characterized in that the reaction mixture contains epoxides which comprise alkoxysilane groups. EP 2 093 244 describes a process by means of which epoxides (such as, for example, propylene oxide and alkoxysilane-containing epoxides) alkoxysilane-containing polyethers are prepared. The alkoxysilane groups can be lined up in any desired block-like manner in said polyether or can be randomly incorporated into the modified polymer chain. See especially Examples 1-4 of this document. In contrast to the prepolymers described above, the alkoxysilanes are not only attached to the termini of the chains. The publications DE 10 2010 038 768, DE 10 2010 038 774 and DE 10 2011 006 313 disclose further developments of the alkoxysilane-containing polyethers according to the process of EP 2 093 244. DE 10 2010 038 768 and DE 10 2010 038 774 describe possibilities to stabilize or block the terminal OH groups of these alkoxysilane polyethers so that no undesired condensation of these OH groups with the alkoxysilanes can take place. The alkoxysilane polyethers on which these patent applications are based are prepared in accordance with the process underlying EP 2 093 244 and modified at the terminal OH group. According to the technical teaching of the patent DE 10 2011 006 313, longer-chain polyethers are used as starting molecules in the three aforementioned publications, otherwise the synthesis of the described polymers is likewise based on the teaching of EP 2 093 244.

Another possibility for producing alkoxysilane-containing polymers is based on the reaction of unsaturated compounds. Once, one can react a polymeric compound with unsaturated groups with a hydrosilane as part of a hydrosilylation of the double bond.

Another possibility is the copolymerization of unsaturated monomers having C =C double bonds with those monomers having polymerizable C =C double bonds which carry an alkoxysilane group. For discussion of these two options see US 4,368,297, column 3, lines 37-42. In US 4368 297 according to Example 1, the hydrosilylation of a Allylgruppen-containing acrylate polymer with methyldimethoxysilane described. Examples 6 and 7 disclose the radical polymerization of unsaturated monomeric compounds without alkoxysilane radical (methacrylate compounds and maleic anhydride) in the presence of proportions of alkoxysilane-containing methacrylate compounds. No. 5,886,125 describes the copolymerization of hydroxypropyl methacrylate, an unsaturated silane-free monomer, and vinyltrimethoxysilane. In WO 00/55229 examples of alkoxysilane-containing polymers of unsaturated monomers are also mentioned. The synthesis of the silane polymer 1 (page 15, line 25) is carried out by radical polymerization of styrene, isobornyl methacrylate and two other silane-free monomers, with methacroyloxypropyltrimethoxysilane. Similar products of silane-free acrylates, styrene and vinylsilane are described in WO 01/078486 in Examples 1-11. In EP 2 01 1 834, Example 1 describes the hydro silyli tion of an allyl group-containing polymer with trimethoxysilane.

However, the polymer backbone is not limited to the above-described groups (polyurethane (pre) polymers, polymeric polyisocyanates, epoxide polymers and C =C ^' -hydrocarbon-containing polymers.) In addition, many other groups are also conceivable. as mentioned in EP 2 01 1 834 in column [016].

Prepolymers known from the prior art contain at least one alkoxysilyl radical as silane functionality. Depending on the alkoxy radical contained and depending on the attachment, alkoxysilyl radicals can be differently reactive as the silane functionality. If a methylene group is located between the functional group and the alkoxysilyl radical and binds this methylene group to the silicon atom of the alkoxysilyl radical, this is referred to as alpha-alkoxysilanes. If there are three methylene groups (i.e., 1,3-propanediyl) between the functional group and the silicon atom of the alkoxysilyl group and bind to the silicon atom, this is called a gamma-alkoxysilane. The alpha-silanes are particularly reactive, but often so reactive that these materials are difficult to process. In addition, they are expensive to produce, expensive and not very widely available commercially.

For the much wider available gamma-silanes, the methoxysilanes are much more reactive than the ethoxysilanes. The disadvantage of using methoxysilane-functionalized polymers is that they release methanol when crosslinked with water. Methanol and its metabolites are toxic to humans and may cause undesirable effects. The gamma-ethoxysilanes are preferred over the methoxysilanes, but are very slow in their reactivity. As a result, these materials can very often not be used technically, especially when crosslinking to the degree of dry air is required within a few hours. is taken. The known catalyst systems described in the literature are not suitable for the curing of the gamma-ethoxysilanes, because the curing rate is often not sufficiently fast despite the use of known catalyst systems. Thus, there remains a need to develop new catalyst systems for the accelerated curing of alkoxysilane-based polymers, particularly for the curing of ethoxysilane-functionalized polymers, especially ethoxysilane-functionalized STPs.

Catalysts for the accelerated hydrolysis and condensation of alkoxysilane groups are well known. The reaction can be catalyzed by acids, bases, organic tin compounds, amines, titanium, zirconium, aluminum, zinc, phosphorus or bismuth compounds. See, for example, F.D. Osterholtz and E.R. Pohl, J. Adhesion Sci. Technol. Vol 6, No 1, pages 127-149 (1992) and the published patent applications WO 2013/174940, DE 10 2005 045 228 and EP 2 813 528. These catalysts have been used in the past predominantly for the crosslinking of gamma-methoxysilanes.

Anions such as alkoxide or hydroxide are known catalysts for the crosslinking of alkoxy silanes.

Pierre and Pajonk, Chem. Rev. 2002, 102, 4243 mention the catalytic action of fluoride ions for the preparation of aerogels from tetraethoxysilanes. The consideration refers to tetraalkoxysilane. The effect of the fluoride anions on the curing of coatings, as well as adhesives, each containing predominantly silane-functionalized (pre) polymers, in particular polyurethane-containing silane-functionalized (pre) polymers, is not mentioned. In contrast to tetraethoxysilane, such silane-functionalized (pre) polymers also contain Si-C bonds in addition to Si-O bonds. The fluoride ion catalysis in the cited literature is not related to curing processes of coatings or splices with ambient humidity. Furthermore, there is no reference in any of these prior publications to the advantageous use of hydrogen polyfluorides, i. Adducts of hydrogen fluoride (HF) and fluoride ions, for silane hardening.

The object of the present invention is therefore to provide compositions based on silane-functionalized (in particular silane-terminated) polymers or corresponding prepolymers which overcome the disadvantages of the prior art and rapid curing, preferably without the release of methanol, allows.

It has now been found that, as a first subject of the invention, compositions comprising at least one silane-functional prepolymer having at least one alkoxysilane group (preferably at least two alkoxysilane groups) and at least one compound containing at least one hydrogen polyfluoride anion accomplish this task. The combination of alkoxysilane group containing prepolymers (especially of alkoxysilane-terminated prepolymers) with a hydrogen polyfluoride anion as a catalyst leads to coating and adhesive and sealing systems that cure very quickly. Particularly surprising is the fact that hereby also ethoxysilane-containing prepolymers can cure very quickly. As used in this application, the term "aliphatic" is intended to mean optionally substituted, linear or branched, alkyl, alkenyl and alkynyl groups in which non-adjacent methylene groups (-CH ₂ -) are substituted by heteroatoms, such as in particular oxygen and sulfur, or may be replaced by secondary amino groups.

As used in this application, the term "alicyclic" or "cycloaliphatic" is intended to mean optionally substituted, carbocyclic or heterocyclic compounds which do not belong to the aromatic compounds, such as, for example, cycloalkanes, cycloalkenes or oxa-, thia-, aza- or Thiazazykloalkane. Specific examples thereof include cyclohexyl groups, cyclopentyl groups, and their derivatives interrupted by one or two or O atoms, e.g. Pyrimidine, pyrazine, tetrahydropyran or tetrahydro-dro. Further examples of alicyclic groups are polyisocyanates having ring structures such as e.g. Iminooxadiazinedione, oxadiazinetrione, oxazolidinone, allophanate, cyclic isocyanurate, cyclic uretdione, cyclic urethane, cyclic biuret, cyclic urea, acylurea and / or carbodiimide structures.

As used in this application, the term "optionally substituted" or "substituted" in particular for a substitution of the relevant structural unit by -F, -Cl, -I, -Br, -OH. -OCH ₃ , -OCH ₂ CH ₃ , -O-isopropyl or -O-n-propyl, -OCF ₃ , -CF ₃ , -S-

Cj.g-alkyl and / or another, optionally linked via a heteroatom linear or branched, aliphatic and / or alicyclic structural unit having 1 to 12 carbon atoms. Preferably, it represents a substitution by halogen (especially -F, -Cl), Ci - «- alkoxy (especially methoxy and ethoxy), hydroxy, trifluoromethyl and trifluoromethoxy. As used in this application, the term "low molecular weight" is intended to mean compounds whose molecular weight is up to 800 g / mol.

As used in this application, the term "high molecular weight" is intended to mean compounds whose molecular weight exceeds 800 g / mol.

As used in this application, the term "polyisocyanate" for aliphatic, aromatic or cycloaliphatic polyisocyanates having an NCO functionality of> 1, preferably> 2, in particular di- and triisocyanates. As used in this application, the term "monomer" is intended to be a low molecular weight compound having functional groups involved in the construction of polymers and having a defined molecular weight.

As used in this application, the term "polymer" is intended to mean compounds in which monomers of the same or different type are repeatedly linked to one another and which may differ with regard to the degree of polymerization, molecular size distribution or chain length. A polymer according to the present invention is thus a compound which has in its molecular structure at least one at least one repeating structural unit which has been covalently inserted into the molecular structure during polymer synthesis by participation of a monomer.

As used in this application, the term "prepolymer" is intended to mean a polymer having functional groups. Analogously to the polymer definition, at least two monomers of the same or different type are repeatedly linked to form the molecular structure of the prepolymer. The prepolymer is involved in the final construction of polymers that have a larger molecular weight than the prepolymer. The prepolymer term thus encompasses polymeric compounds which are each reactive via at least one functional group contained in the molecule and can react to form a (preferably crosslinked) polymer to form a repeating unit. Thus, as is common in polyurethane chemistry, the prepolymer term likewise includes preferred polyurethane compounds which contain at least one diisocyanate and at least one diol unit, or at least two diisocyanate or at least two hydroxyl or amino groups and via the functional groups of these "Alkoxysilane-functionalized prepolymers" contain at least one alkoxysilane group as functional group (optionally in addition to other functional groups). "Alkoxysilane-functionalized prepolymers include both" alkoxysilane-functionalized polyurethane prepolymers "and" alkoxysilane ". functionalized polymeric polyisocyanates "with, as well as the aforementioned alkoxysilane-containing polymers according to the patents EP 2093244, DE 102010038768, DE 102010038774 and DE102011006313, and alkoxysilane-containing polymers according to the publications WO 00/55229 , WO 03/078486, US 5162426 and US 5886125. The term "blocked" means "reversibly blocked" in the context of this application. For example, can be released from a blocked isocyanate group by heating isocyanate again; blocked isocyanate groups are therefore still reactive with polyols. Typically, a blocked isocyanate is understood as meaning an addition compound of a highly reactive isocyanate with an alcohol (to a urethane) or an amine (to a urea) which reverts to alcohol or amine and isocyanate at higher temperatures. Known blocking agents are, for example, acetoacetic acid, malonic esters, 3, 5-dimethylpyrazole, butanone oxime, secondary amines, caprolactam or various alcohols.

Unless otherwise clear from the context, in this application the term "isocyanate group" always includes both free isocyanate groups (-NCO) and blocked isocyanate groups.

Preferred silane-functional prepolymers having at least one alkoxysilane group have a number-average molecular weight Mn of at most 20,000 g / mol, preferably at most 15,000 g / mol, particularly preferably at most 10,000 g / mol.

Preferred silane-functional prepolymers having at least one alkoxysilane group have a number-average molecular weight Mn of at least 500 g / mol, preferably at least 800 g / mol.

By molecular weight, in compounds whose molecular weight does not result from a well-defined structural formula, e.g. in polymers, each to understand the number average molecular weight. The number average molecular weight Mn is determined by gel permeation chromatography (GPC) in tetrahydrofuran at 23 ° C. The procedure is as described in DI 55672-1: "Gel Permeation Chromatography, Part 1 - Tetrahydrofuran as Eluent" (SECurity GPC system from PSS Polymer Service, flow rate 1.0 ml / min, columns: 2xPSS SDV linear M, 8x300 mm, 5 μηι; RI D detector). This polystyrene samples of known molecular weight are used for calibration. The calculation of the number average molecular weight is software-based. Baseline points and evaluation limits are defined in accordance with DIN 55672 Part 1 valid on the filing date of this patent application.

The composition according to the invention preferably contains at least one silane-functional prepolymer containing at least one alkoxysilane group (preferably at least two alkoxysilane groups) of the general formula (I)

* - ^R - ^Si < ^{R 1} > 3-a < ^{OR 2} > a ", where

R ^{1 is} an alkyl group having 1-8 C atoms; R ^{2 is} an alkyl group having 2 to 12 C atoms; R ^{3 is} a linear or branched, optionally cyclic, alkylene group having 2 to 12 C atoms, optionally with aromatic moieties, and optionally with one or more heteroatoms; and a is a value of 1 or 2 or 3. * in formula (I) stands for a free valency of the residue / structural fragment marked thereby, to which the prepolymer binds.

It is preferred according to the invention if R 1 of the formula (I) is a methyl group or an ethyl group, particularly preferably a methyl group.

It is preferred according to the invention if R 2 of the formula (I) for each radical O ^{- of} the formula (I) is independently a methyl group or an ethyl group, particularly preferably an ethyl group. In this case, the alkoxy radicals of the alkoxy group of the silane-functional prepolymer are selected from ethoxy and / or methoxy groups, in particular ethoxy groups.

It is preferred according to the invention if R 3 of the formula (I) is an alkylene group having 2 to 6 carbon atoms, in particular having 2 to 3 carbon atoms, particularly preferably propane-1,3-diyl.

It is preferred according to the invention that at least at the terminus of the silane-functional prepolymer each binds an alkoxysilane group. In addition to or instead of the binding of the alkoxysilane group at the terminus, further alkoxysilane groups can be distributed over the polymer backbone and bound to the prepolymer. Very particular preference is given to silane-functional polyurethane prepolymers in which an alkoxysilane group (in particular of the formula (I)) in each case binds at the terminus.

Suitable silane-functionalized prepolymers are polyurethanes having at least one alkoxysilane group, polymeric polyisocyanates having at least one alkoxysilane group, polyether polyols having at least one alkoxysilane group, polyester polyols having at least one alkoxysilane group, polycarbonate polyols having at least one alkoxysilane group, polyacrylate polyols having at least one alkoxysilane group , Polymethacrylate polyols having at least one alkoxysilane group and polyurethane polyols having at least one Alkoxysi langrupp e.

Furthermore, the composition according to the invention contains a compound having at least one hydrogen polyfluoride anion. This compound acts as a catalyst for crosslinking or

Curing of said silane-functionalized prepolymer in the presence of moisture. Moisture is the presence of water, especially in the form of humidity, Understood. The compositions according to the invention are cured by ambient air humidity to give stable polymers and are used in the field of automobile priming, automotive refinishing, corrosion protection and silane-terminated polyurethane prepolymers for sealing and bonding applications. In a first embodiment, the silane-functional polymer is a silane-functional polyurethane prepolymer which is obtainable by reacting a silane which has at least one isocyanate-reactive group with a polyurethane polymer which has isocyanate groups (the latter also below: isocyanate-functional prepolymer). This polyurethane prepolymer is prepared by the reaction of a compound having such cyanate-reactive groups or mixtures of such materials and polyisocyanates, the isocyanate groups being used in excess of the cyanate-reactive groups.

Useful polymeric polyols for the preparation of the prepolymers have a number average molecular weight M _{n of} from 400 to 8000 g / mol, preferably from 400 to 6000 g / mol and more preferably from 400 to 3000 g / mol. Their hydroxyl number is 22 to 400 mg KOH / g, preferably 30 to 300 mg KOH / g and particularly preferably 40 to 250 mg KOH / g and have an OH functionality of 1.5 to 6, preferably 1.7 to 5 and more preferably from 2.0 to 5 on.

Polyols for the preparation of the prepolymers are the organic polyhydroxyl compounds known in polyurethane coating technology, such as, for example, the conventional polyester polyols, polyacrylate polyols, polyurethane polyols, polycarbonate polyols, polyether polyols, polyester polyacrylate polyols and polyurethane polyacrylate polyol, polyurethane polyester polyols, polyurethane polyether polyols, polyurethane polycarbonate polyols, polyester polycarbonate polyols, phenol / formaldehyde resins , alone or in mixtures. Preference is given to polyesterpolyols, polyetherpolyols, polyacrylatepolyols or polycarbonatepolyols; polyetherpolyols, polyetherpolyols and polycarbonatepolyols are particularly preferred. Examples of suitable polyether polyols are the polyaddition products of styrene oxides, ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide, epichlorohydrins, and their Mischadditions- and graft products, and the polyether polyols obtained by condensation of polyhydric alcohols or mixtures thereof and by alkoxylation of polyhydric alcohols, amines and amino alcohols called. Suitable hydroxy-functional polyethers have OH functionalities of 1.5 to 6.0, preferably 1.8 to 3.0, OH numbers of 50 to 700, preferably 100 to 600 mg KOH / g solids and molecular weights M _n of 106 to 4000 g / mol, preferably from 200 to 3500, such as alkoxylation of hydroxy-functional starter molecules such as ethylene glycol, propylene glycol, butanediol, hexanediol, trimethylolpropane, glycerol, pentaerythritol, sorbitol or mixtures these and other hydroxy-functional compounds with propylene oxide or butylene oxide. Preferred polyether components are polypropylene oxide polyols, polyethylene oxide polyols and polytetramethylene oxide polyols.

Highly suitable examples of polyester polyols are the on are the known polycondensates of di- and optionally tri- and tetraols and di- and optionally tri- and tetracarboxylic acids or hydroxycarboxylic acids or lactones. Instead of the free polycarboxylic acids, it is also possible to use the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols for the preparation of the polyesters. Examples of suitable diols are ethylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycols such as polyethylene glycol, furthermore 1,2-propanediol, 1,3-propanediol, butanediol (1,3), butanediol (1,4), hexanediol (l , 6) and isomers, neopentyl glycol or hydroxypivalic acid neo-pentylglycol ester, the latter three compounds being preferred. In order to achieve a functionality> 2, polyols having a functionality of 3 may be used proportionally, for example trimethylolpropane, glycerol, erythritol, pentaerythritol, trimethylolbenzene or trishydroxyethyl isocyanurate.

Suitable dicarboxylic acids are, for example, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, glutaric acid, tetrachlorophthalic acid, maleic acid, fumaric acid, itaconic acid, malonic acid, suberic acid, 2-methylsuccinic acid, 3, 3-diethylglutaric acid, 2, 2-dimethyl-succinic acid. Anhydrides of these acids are also useful, as far as they exist. As a result, for the purposes of the present invention, the anhydrides are encompassed by the term "acid". Monocarboxylic acids such as benzoic acid and hexanecarboxylic acid may also be used, provided that the average functionality of the polyol is> 2. Saturated aliphatic or aromatic acids are preferred, such as adipic acid or isophthalic acid. As polycarboxylic acid which may optionally be used in smaller amounts, trimellitic acid may be mentioned here.

Hydroxycarboxylic acids which may be used as reactants in the preparation of a hydroxyl-terminated polyester polyol include hydroxycaproic acid, hydroxybutyric acid, hydroxydecanoic acid, hydroxystearic acid and the like. Useful lactones include caprolactone, butyrolactone and homologs. Preference is given to polyester polyols based on butanediol and / or neopentyl glycol and / or hexanediol and / or ethylene glycol and / or diethylene glycol with adipic acid and / or phthalic acid and / or isophthalic acid. Particularly preferred are polyester polyols based on butanediol and / or neopentyl glycol and / or hexanediol with adipic acid and / or phthalic acid. - II -

The candidate polycarbonate polyols are prepared by reaction of carbonic acid derivatives, e.g. Diphenyl carbonate, dimethyl carbonate or phosgene with diols available. As such diols come e.g. Ethylene glycol, 1,2- and 1,3-propanediol, 1,3- and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, 1,4-bishydroxymethylcyclohexane, 2-methyl-1,3- propanediol, 2,2,4- Trimethylpentandiol- 1, 3, dipropylene glycol, polypropylene glycols, dibutylene glycol, polybutylene glycols, bisphenol A, tetrabromobisphenol A, but also lactone-modified diols in question. Preferably, the diol component contains from 40 to 100% by weight of 1,6-hexanediol and / or hexanediol derivatives, preferably those having, in addition to terminal OH groups, ether or ester groups, e.g. Products obtained by reacting 1 mole of hexanediol with at least 1 mole, preferably 1 to 2 moles of ε-caprolactone or by etherification of hexanediol with itself to di- or Trihexylenglykol. Polyether-polycarbonate polyols can also be used.

Preference is given to polycarbonate polyols based on dimethyl carbonate and hexanediol and / or butanediol and / or ε-caprolactone. Very particular preference is given to polycarbonate polyols based on dimethyl carbonate and hexanediol and / or ε-caprolactone.

Instead of the above-described polymeric polyether, polyester or polycarbonate polyols, it is also possible to use low molecular weight polyols in the molecular weight range from 62 to 400 g / mol for the preparation of the isocyanate-containing prepolymers. Suitable low molecular weight polyols are short chain, i. 2 to 20 carbon atoms, aliphatic, araliphatic or cycloaliphatic diols or triols. Examples of diols are ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 2-ethyl-2-butylpropanediol, trimethylpentanediol, 2,2,4-trimethyl-1,3-pentanediol, positionally isomeric diethyloctanediol, 1,3-butylene glycol, cyclohexanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, 1,2- and 1,4-cyclohexanediol, hydrogenated bisphenol A (2,2-bis (4-hydroxycyclohexyl) propane), 2,2-dimethyl-3-hydroxypropionic acid (2,2-dimethyl-3-hydroxypropyl ester). Preference is given to 1,4-butanediol, 1,4-cyclohexanedimethanol and 1,6-hexanediol. Examples of suitable triols are trimethylolethane, trimethylolpropane or glycerol, preference is given to trimethylolpropane.

The stated polyols can be used alone or in a mixture. The above-mentioned isocyanate-reactive compounds can be reacted with all diisocyanates, aromatic as well as aliphatic before the actual prepolymerization to urethane-modified hydroxyl compounds.

Suitable isocyanate-containing components are aromatic, aliphatic and cycloaliphatic diisocyanates and mixtures thereof. Suitable diisocyanates are compounds of the formula PIC (NCO) 2 having an average molecular weight below 400 g / mol, wherein PIC is a C6-C15 aromatic hydrocarbon radical, a C4-C12 aliphatic hydrocarbon radical or a cyclo-aliphatic Ce-Cn-carbon radical first, for example Diisocyanates from the series butane diisocyanate, 1,5-pentanediisocyanate (PDI), 1,6-hexanediisocyanate (hexamethylene diisocyanate, HDI), 4-isocyanatomethyl-1,8-octane diisocyanate (triisocyanatononane, TIN) 4,4'-methylenebis (cyclohexyl isocyanate) , 3,5,5-trimethyl-1-isocyanato-3-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 2,4- and / or 2,6-methylcyclohexyl diisocyanate (IL TDI) and ω, ω'-diisocyanate 1, 3 -dimethylcyclohexane (H, XDI), xylylene diisocyanate (XDI), 4,4'-diisocyanatodicyclohexylmethane, tetramethylene diisocyanate, 2-methylpentamethylene diisocyanate, 2,2,4-trimethylhexamethyl endii so cyanoate (TU Di) , Dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 4,4'-diisocyanato-3,3'-dimethyl-dicyclohexylmethane, 4,4'-diisocyanatodicyclohexylpropane (2,2), 3-isocyanatomethyl-1-methyl-1-isocyanatocyclohexane (MCI ), 1, 3 -Diisooctylcyanato-4-methylcyclohexane, 1, 3 -diisocyanato-2-methyl-cyclohexane and α, α, α ', α'-tetramethyl-m- or -p-xylylen- diisocyanate (TMXDI) , 2,4- / 2,6-toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), naphthylene diisocyanate (NDI). Preference is given here I DI. H DI. PDI or TDI or MDI derivatives used.

Of course, it also includes the use or co-use of the polymeric polyisocyanates mentioned below, as well as, for example, in the form of their derivatives such as urethanes, biurets, allophanates, uretdiones, isocyanurates and trimers and mixed forms of these derivatizations.

In principle, it is also possible to use mixtures of a plurality of isocyanates, but it is preferred to use only one isocyanate.

For the synthesis of an isocyanate-functional prepolymer, an excess of the polyisocyanate component, preferably an NC O: YH ratio (Y = O, N or S) of 1.3: 1.0 to 5.0: 1, 0 is particularly preferably from 1, 5: 1.0 to 3.0: 1, 0 and most preferably from 1.5: 1.0 to 2.5: 1, 0 selected.

This urethanization can be accelerated by catalysis. To accelerate the NCO-OH reaction, the person skilled in the known urethanization catalysts such as organotin compounds, Bismuthverbindungen, zinc compounds, titanium compounds, zirconium compounds or amine catalysts in question.

In the production process, this catalyst component, if used, in amounts of 0.001 wt .-% to 5.0 wt .-%, preferably 0.001 wt .-% to 0.1 wt .-% and particularly preferably 0.005 wt .-% to 0 , 05 wt .-% based on the solids content of the process product used. The urethanization reaction is carried out at temperatures of 20 ° C to 200 ° C, preferably 40 ° C to 140 ° C and more preferably from 60 ° C to 120 ° C.

The reaction is continued until a (preferably complete) conversion of the isocyanate-reactive groups is achieved. The course of the reaction is usefully monitored by checking the NCO content and is complete when the corresponding theoretical NCO content is reached and constant. This can be monitored by suitable measuring devices installed in the reaction vessel and / or by analyzes on samples taken. Suitable methods are known to the person skilled in the art. These are, for example, viscosity measurements, measurements of the NCO content, the refractive index, the OH content, gas chromatography (GC), nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR) and near near-infrared spectroscopy (NIR). Preferably, the NCO content of the mixture is determined titrimetrically.

It does not matter if the process is continuous, e.g. in a static mixer, extruder or kneader or discontinuously e.g. is carried out in a stirred reactor.

The process is preferably carried out in a stirred reactor. If the conversion of polyisocyanate was not complete, unreacted polyisocyanate can be removed from the prepolymer by continuous distillation. A continuous distillation process is understood here to mean a process in which only a respective subset of the prepolymer from the previously described process step is briefly exposed to an elevated temperature, while the amount not yet in the distillation process remains at a significantly lower temperature. The term "elevated temperature" is to be understood as meaning the temperature required for the evaporation of the volatile constituents at a correspondingly selected pressure.

Preferably, the distillation at a temperature of less than 170 ° C, more preferably 110 to 170 ° C, most preferably 125 to 145 ° C and at pressures of less than 20 mbar, more preferably less than 10 mbar, most preferably at 0.05 to 5 mbar.

The temperature of the prepolymer-containing reaction mixture not yet in the distillation process is preferably from 0 ° to 60 ° C., particularly preferably from 15 ° to 40 ° C. and very particularly preferably from 20 ° to 40 ° C. The temperature increase between the distillation temperature and the temperature of the prepolymer-containing reaction mixture not yet in the distillation process is preferably at least 5 ° C., particularly preferably at least 15 ° C., very particularly preferably from 15 ° to 40 ° C. The distillation is preferably conducted at such a rate that a volume increment of the polymer-containing reaction mixture to be distilled is subjected to the distillation temperature for less than 10 minutes, more preferably less than 5 minutes and then re-heated to the starting temperature of the pre-treatment by active cooling. polymer-containing reaction mixture is brought before the distillation. Preferably, the T emp eraturb el treatment is carried out such that the temperature of the reaction mixture before distillation or the prepolymer after distillation relative to the distillation temperature used at least 5 ° C, more preferably at least 15 ° C, most preferably 15 ° to 40 ° C is higher. Preferred continuous distillation techniques are short-path, falling-film and / or thin-film distillation (see, for example, Chemische Technik, Wiley-VCH, Volume 1, 5th Edition, pages 333-334).

The continuous distillation technique used is preferably thin film distillation with the abovementioned parameters. Another possibility is the provision of a silane-functionalized, polymeric polyisocyanate having at least one alkoxysilane group as a silane-functional prepolymer which is preferred according to the invention in the context of the second embodiment. Said silane-functionalized polymeric polyisocyanates can be synthesized by the direct reaction of polymeric polyisocyanates with alkoxysilanes bearing an isocyanate-reactive group such as amino, mercapto or hydroxy. Aromatic, aliphatic, aliphatic or cycloaliphatic polymeric polyisocyanates with an NCO functionality> 2 are used as suitable polymeric polyisocyanates. These may also have iminooxadiazinedione, isocyanurate, uretdione, urethane, allophanate, biuret, urea, oxadiazinetrione, oxazolidinone, acylurea and / or carbodiimide structures. Suitable diisocyanates for preparing the polymeric polyisocyanates are any diisocyanates which are obtainable by phosgenation or by phosgene-free processes, for example by thermal urethane cleavage, whose isocyanate groups are bonded via optionally branched aliphatic radicals to an optionally further substituted aromatic, such as preferably 1, 4-butane diisocyanate, 1 , 5-pentane diisocyanate (PDI), 1,6-hexane diisocyanate (hexamethylene diisocyanate, HDI), 4-isocyanatomethyl-1,8-octane diisocyanate (triisocyanatononane, TIN) 4,4'-methylenebis (cyclohexyl isocyanate), 3.5 , 5-trimethyl-1-so-cyano-3-cyanoatomethyl eye-lohexane (isophorone diisocyanate, IPDI), 2,4- and / or 2,6-methylcyclohexyl diisocyanate (H ₆ TDI) and ω, ω'- Diisoyanato-1,3-dimethylcyclohexane (HeXDi), 4,4'-diisocyanatodicyclohexylmethane, tetramethylene diisocyanate, 2-methylpentamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate (THDI), dodecamethyl endii so cyanate, 1, 4- D iisocyanatocyclohexane, 4,4'-diisocyanato-3,3'-dime tliyl-dicyclohexylmethane, 4,4'-diisocyanatodicyclohexylpropane (2,2), 3-isocyanatomethyl-1-methyl-1-isocyanatocyclohexane (MCI), 1,3-diisooctylcyanato-4-methylcyclohexane, 1,3-diisobutyl cyanato -2 -m ethylcyclohexane, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, methyl endiphenyl diisocyanate (MDI), naphthyl diisocyanate (NDI), 1,3-bis (isocyanatomethyl) benzene (m-xylylene diisocyanate, m-XDI), 1,4-bis (isocyanatomethyl) benzene (p-xylylene diisocyanate, p-XDI), 1,3-bis (2-i-cyanatopropan-2-yl) benzene (m-tetramethylxylylene diisocyanate, m-TMXDI ), 1, 4-bis (2-isocyanatopropan-2-yl) benzene (p-tetramethylxylylene diisocyanate, p-TMXDI), 1,3-bis (isocyanato-methyl) -4-methylbenzene, 1, 3-bis ( isocyanatomethyl) -4-ethylbenzene, 1, 3-bis (isocyanatomethyl) -5-methylbenzene, 1,3-bis (isocyanatomethyl) -4,5-dimethylbenzene, 1,4-bis (isocyanatomethyl) -2,5-di- methylbenzene, 1,4-bis (isocyanatomethyl) -2,3,5,6-tetramethylbenzene, 1, 3-bis (isocyanatomethyl) -5-tert-butylbenzene, 1,3-bis (isocyanatomethyl) -4-chlorobenzene z, l, 3-bis (isocyanato ethyl) -4,5-dichlorobenzene, 1,3-bis (isocyanatomethyl) -2,4,5,6-tetrachlorobenzene, 1,4-bis (isocyanatomethyl) -2 , 3,5,6-tetrachlorobenzene, 1,4-bis (isocyanatomethyl) -2,3,5,6-tetrabromobenzene, 1,4-bis (2-isocyanatoethyl) benzene, 1,4-bis (isocyanatomethyl) naphthalene and any mixtures of these diisocyanates. Very particular preference is given to dimers of the abovementioned diisocyanates, trimers of the abovementioned diisocyanates or combinations thereof as polymeric polyisocyanate according to the invention to prepare said silane-functional polymeric polyisocyanates.

The preparation of the polymeric polyisocyanate components from the aforementioned diisocyanates by means of known per se modification reactions by reacting a portion of the original isocyanate present in the starting isocyanate groups to form polymeric Polyi so cyanatmol molecules, which consist of at least two Diso cyanatmolekülen.

Suitable such modification reactions are, for example, the customary processes for the catalytic oligomerization of isocyanates to form uretdione, isocyanurate, iminooxadiazinedione and / or oxadiazinetrione structures or for the biuretization of diisocyanates, as described, for example, in US Pat. In Laas et al. J. Prakt. Cham. 336, 1994, 185-200, in DE-A 1 670 666 and EP-A 0 798 299 are described by way of example.

Iso cy anatr eakti ve alkoxysilane compounds for the preparation of inventive silane-functionalized prepolymers (in particular silane-functionalized prepolymers of the first and second embodiments) are well known to those skilled. Examples which may be amino propyltrimethoxysilane, mercaptopropyltrimethoxysilane, mercaptopropyl, amino propylmethyldimethoxysilane, mercaptopropylmethyldimethoxysilane, aminopropyltriethoxysilane, mercaptopropyl, aminopropylmethyldiethoxysilane, Mercaptopropylmethydiethoxysi- lan, aminomethyltrimethoxysilane, aminomethyl triethoxysilane, (aminomethyl) methyldimethoxy- silane, (aminomethyl) methyl, N-butylaminopropyltrimethoxysilane, N -Butylaminopropyltriethoxysilane, iV-ethylaminopropyltrimethoxysilane N-ethylaminopropyltriethoxysilane, N-phenylaminopropyltrimethoxysilane, N-phenylaminopropyltriethoxysilane, N, N-bis (3-trimethoxy) silylpropyl) amine, N, N-bis (3-triethoxysilylpropyl) amine, N, N-bis (3-tri-i-propoxysilylpropyl) amine.

Furthermore, as isocyanate-reactive compounds, the aspartic acid esters can also be used, as described in EP-A 0 596 360. In these molecules of general formula I II

Formula I II means X identical or different alkoxy or alkyl radicals, which may also be bridged, but at least one alkoxy radical must be present on each Si atom, Q is a di functional linear or branched aliphatic radical and Z is an alkoxy radical 1 to 10 carbon atoms. The use of such aspartic acid esters is preferred. Examples of particularly preferred aspartic acid esters are diethyl N- (3-triethoxysilylpropyl) aspartate, diethyl N- (3-triethoxysilylpropyl) aspartate and diethyl N- (3-dimethoxymethylsilylpropyl) aspartate. Very particular preference is given to the use of Λ ^Γ - (3-triethoxysilylpropyl) aspartic acid diethyl ester.

For all of the isocyanate-reactive silane components, the ethoxysilane derivatives are preferred over the methoxy derivatives.

The alkoxysilyl group-containing prepolymers used according to the invention are prepared using isocyanate-reactive alkoxysilane compound by reacting isocyanate-functional prepolymer (preferably those of the first embodiment (isocyanate-functional polyurethane) or the second embodiment (polymeric polyisocyanates)) to the silane-terminated prepolymer by reaction with an isocyanate-reactive alkoxysilane compound. Said reaction with isocyanate-reactive alkoxysilanes is carried out within a temperature range of 0 ° C to 150 ° C, preferably from 20 ° C to 120 ° C, the proportions are generally selected so that per mole of NCO groups used 0.8 to 1 , 3 moles of the isocyanate-reactive alkoxysilane compound are used, preferably 1.0 mole of isocyanate-reactive alkoxysilane compound per mole of NCO groups used. In a third embodiment, the silane-functional prepolymer is a silane-functional prepolymer obtainable by the reaction of an isocyanatosilane with a polymer which has isocyanate-reactive functional end groups, in particular hydroxyl groups, mercapto groups and / or amino groups. Preferred polymers which contain functional groups which are reactive toward isocyanate groups are the abovementioned polymeric polyols, very particularly polyether, polyester, polycarbonate and polyacrylate polyols, and also polyurethane polyols prepared from polyisocyanates and the stated polyols. It is also possible to use mixtures of all the stated polyols.

Isocyanate-functional alkoxysilane compounds are in principle suitable for all alkoxysilane-containing monoisocyanates having a molecular weight of from 140 g / mol to 500 g mol. Examples of such compounds are isocyanatomethyltrimethoxysilane, isocyanatomethyltriethoxysilane, (isocyanatomethyl) methyldimethoxysilane, (isocyanatomethyl) methyldiethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropylmethyldimethoxysilane, 3-isocyanatopropyltriethoxysilane and 3-isocyanatopropylmethyldiethoxysilane. Preferred here is the use of 3 -I so cyanatopropyltrimethoxy silane or 3-isocyanatopropyltriethoxysilane, very particularly preferably the use of 3-iso cyanatopropyltri ethoxy silane.

It is also possible according to the invention to use isocyanate-functional silanes which have been prepared by reacting a diisocyanate with an amino or thiosilane, as described in US Pat. No. 4,146,585 or EP-A 1 136 495. The reaction of the isocyanatosilanes with the polyols preferably used is carried out in the same manner as described above for the preparation of the isocyanate-containing prepolymer from the polyisocyanate component with the polyol component.

The ratio of the NCO groups of the isocyanatosilane to the isocyanate-reactive groups, preferably the hydroxyl groups of the polyols, is between 0.5: 1 and 1: 1, preferably between 0.75: 1 and 1: 1, very particularly preferably between 0 , 9: 1 and 1: 1.

In a fourth embodiment, the silane functional polymer is a silane functional polymer obtainable by a hydrosilylation reaction of double bond polymers, for example, poly (meth) acrylate polymers and polyether polymers, especially allyl terminated polyoxyalkylene polymers described, for example, in US 3,071,751 and US 6,207,766.

In addition, such alkoxysilane-containing polymers can be cured by the inventive catalysis, which are described in the cited in the introduction of this patent application publications. Furthermore, the composition according to the invention comprises at least one compound having at least one hydrogen polyfluoride anion for the crosslinking of silane-functional prepolymers. The compound having at least one hydrogen polyfluoride anion acts as a catalyst for crosslinking the alkoxysilane groups of the prepolymer. The compound having at least one hydrogen polyfluoride anion is preferably selected from at least one compound of the group formed from adducts of at least one fluoride anion and hydrogen fluoride (hydrogen polyfluorides), more preferably selected from at least one adduct of at least one fluoride anion and hydrogen fluoride. Hydrogen polyfluorides are sometimes commercially available or can be prepared in a simple manner and in any stoichiometry by mixing appropriate fluorides with the desired amount of HF.

It is irrelevant in which form hydrogen fluoride is added. This can be in pure form, i. H. be in the liquid or gaseous state. Easy to handle but also z. B. HF solutions in protic or aprotic organic solvents. Commercially available and relatively safe to handle are also HF amine complexes, eg. With amines such as triethylamine, pyridine or melamine.

In contrast to the free hydrogen fluoride, which behaves physiologically unpleasant, Hydrogenpolyfluoride are unproblematic.

With particular preference the composition according to the invention contains as compound with at least one fluoride anion at least one compound of the general formula II.

{M [n F ^{~ »m} (HF)]} (II) wherein M represents an equivalent of one or more cations optionally bearing a charge number equal to n as cationic charge and causes the electroneutrality of the compound of formula (II), n stands for the number 1 m stands for a number from 1 to 5. It is inventively preferred if m according to formula (II) is a number from 1 to 5.

Very particular preference according to formula (II) n is 1 and m is 1.

The "HF content" in the compounds of the formula (II) can vary within wide limits. This means that it is irrelevant whether they are defined monohydrogendifluorides (m = n = 1 in formula II), hydrogentrifluoride (n = 1 & m = 2 in formula II), etc., which are known, for example, in the form of their potassium salts with the corresponding stoichiometry (Hollemann-Wiberg, Lehrbuch der Inorganischen Chemie, 91.-100th ed., W. de Gruyter Verlag, Berlin, New York, 1985, p. 408, footnote 50) or any mixtures of the latter with excess fluoride on the one hand or HF on the other hand.

M is an equivalent of one or more cations that preserve the electroneutrality of the compound. For example, for n = 1 and m = 1 and the cation Ca ²⁺ , the equivalent required for electroneutrality is M = 0.5 Ca ^{2 *} . Examples of cations which may be used are alkali metal or alkaline earth metal cations and tetraalkylammonium and tetraalkylphosphonium compounds, the alkyl groups of the tetraalkylammonium or tetraalkylphosphonium groups preferably being linear or branched, optionally cyclic, alkylene groups composed of 2 to 12 C atoms , consist.

According to the invention, those compositions are preferred which are characterized in that the compound having at least one fluoride anion of the formula (II) contains an n-fold charged cation as M, and n = 1 and m = 1.

Compositions in which the compound having at least one fluoride anion has a structure of the general formula II given with n = 1 and m = 1 and the cation M is selected from alkali metal ions, tetraalkylammonium or tetraalkylphosphonium ions or mixtures thereof are particularly preferred. In this case, it is again preferred if the composition according to the invention comprises at least one compound of the formula (II) in which M is a tetraalkylammonium or tetraalkylphosphonium or piperidinium-1-spiro-1'-pyrrolidinium ion, in particular a tetrabutylammonium or a tetrabutylphosphonium ion.

Preference is given to systems of the general formula I which contain tetraalkylammonium or tetraalkylphosphonium ions and mixtures thereof as cationic constituents. Preferred anions are those of the general structure 11 with n = 1 and m = 1-5 and mixtures thereof, very particular preference is given to structures of the formula 11 where n = 1 and m = 1.

Such quaternary ammonium / phosphonium fluorides and hydrogen difluorides are described, for example, by Dermeik and Sasson, J. Org. Chem. 1989, 54. 4827-4829 and in the patent applications DE 196 11 849, EP 0962 455 A1 and WO 2015/124504. It is possible to use as catalyst at least one compound of the formula (II-1):

in which E is N or P, R is the same or different, optionally branched, optionally cyclic, optionally substituted (O, N, halogen) aliphatic, araliphatic and aromatic radicals each having 1 to 25 C atoms and m is: m is a number between 0 and 5, more preferably m is 0 or 1, most preferably m is 1. Preference is given as such catalysts compounds of formula (II-1) are used, wherein E is N and P, R is the same or different, optionally branched, optionally substituted (O, N, halogen) (cyclo) aliphatic and araliphatic radicals each having 1 to 20 C atoms and m is a number between 1 and 5, most preferably m is 1.

An example of the latter are Benzyltrimethylammoniumhydrogenpolyfluoride of formula (II-2): C 6 H ₅ CH ₂ (CH ₃₎ 3 N ⁺ [F m (HF)] (II-2), as well as Tetraalkylammoniumhydrogenpolyfluoride of formula (Π-3) and T etraalkylpho Sphonium hydrogen polyfluorides of the formula (II-4):

R ₄ N ⁺ [F- m (HF)] (II-3),

R ₄ P ⁺ [F ^" m (HF)] (II-4), wherein R is identical or different, optionally branched, (cyclo) aliphatic radicals each having 1 to 20 C-atoms or in each case independently of one another two radicals R together form a 5-membered or 6-membered ring with the quaternary nitrogen atom or the quaternary phosphorus atom, and m is a number between 1 and 5.

Particular preference is given to using compounds of the formula (Π-5) and / or of the formula (II-6) as catalyst:

R ₃ (R ') N ⁺ [F ^" m (HF)] (II-5),

R ₃ (R ') P ⁺ [F ^" m (HF)] (II-6), wherein

R is identical or different, optionally branched, aliphatic radicals each having 1 to 15 C-atoms, R 'is optionally branched, aliphatic radicals having 1 to 4 C-atoms and m is a number from 1 to 5, very particularly preferably m is 1.

Preferred compounds having at least one hydrogen polyfluoride anion are selected from at least one compound of the group which is formed from tetrabutylammonium hydro- gendifluoride, tetrabutylphosphonium hydrogendifluoride, piperidinium-1-spiro-1'-pyrrolidinium hydrogendifluorid.

It may be a single compound having at least one hydrogen polyfluoride anion or, in certain cases, a mixture of various of these compounds. The total amount of compound having at least one hydrogen polyfluoride anion on the composition according to the invention is from 0.1 to 10% by weight, preferably from 0.2 to 5% by weight and more preferably from 0.2 to 3% by weight.

The compound having at least one hydrogen polyfluoride anion (or mixtures of several of these compounds) may also be diluted with a solvent. Of course, it is possible or in some cases even preferred to use mixtures of different compounds with at least one fluoride anion.

The composition according to the invention, when it is carried out as a coating agent, may additionally contain auxiliaries and / or additives known in coating technology, such as stabilizers, light stabilizers, fillers, pigments, matting agents, flame retardants, water scavengers, adhesion promoters, leveling agents or rheological aids. If necessary, conventional inorganic or organic colorants and / or effect pigments can also be present in the coating system in coating technology.

Depending on the requirements of the problems to be solved by the application, these aids are admixed with the inventive mixture of silane component and compound having at least one hydrogen polyfluoride anion (catalyst). The amounts of these excipients may also be significantly lower and are determined by the intended application. For applications in the field of corrosion protection or adhesives, the amount of auxiliaries may be> 50%, based on the mixture of silane component and catalyst used, very low when used for example Topcoats. The composition according to the invention may additionally contain solvents. Examples of such solvents are 2-ethylhexanol, acetone, 2-butanone, methyl isobutyl ketone, butyl acetate, ethyl acetate, 1-methoxy-2-propyl acetate (MPA), 3-methoxy-1-butyl acetate, propylene-n-butyl ether, toluene, methyl ethyl ketone, xylene , 1,4-dioxane, diacetone alcohol, N-methylpyrrolidone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, methyl ethyl ketone, solvent naphtha (hydrocarbon mixture) or any mixtures of such solvents.

Preferred solvents here are the solvents customary in polyurethane chemistry, such as butyl acetate, ethyl acetate, 1-methoxy-2-propyl acetate (MPA), 3-methoxy-1-butyl acetate, propylene-n-butyl ether, toluene, 2-butanone, xylene, 1,4-dioxane, ethyl ethyl ketone, N-methyl pyrrolidone, dimethylacetamide, dimethylformamide, methyl ethyl ketone, solvent naphtha (hydrocarbon mixture) or any mixtures of such solvents.

Particularly preferred solvents are solvents, such as butyl acetate, 1-methoxy-2-propyl acetate (MPA), 3-methoxy-1-butyl acetate, ethyl acetate, propylene-n-butyl ether, methyl ethyl ketone, toluene, xylene, solvent naphtha (hydrocarbon mixture). as well as their mixtures.

The compositions of the invention can be used as coating agents, adhesives and sealants. The formulations for coating can be used as a pigment-free system, i. be formulated as a clearcoat, as well as a pigmented system. Pigment-free systems can be used as clearcoats, for example for the coating of metal surfaces in automotive finishing (automotive OEM and automotive refinishing).

Coating formulations with fillers and / or pigments can be used in the field of corrosion protection. In addition, formulations of the systems according to the invention in pigmented form can also be used as adhesives or sealants.

The invention additionally relates to the use of a compound having at least one hydrogen polyfluoride anion, for crosslinking alkoxysilane-group-containing, in particular alkoxysilane-terminated polymers with moisture, more particularly for crosslinking ethoxy silane groups.

Preferred polymers and preferred compounds having at least one hydrogen polyfluoride anion are those defined in the first subject of the invention (vide supra). A further subject of the invention is a method for bonding, sealing or coating a substrate, comprising a step in which a composition of the first subject of the invention is applied to a substrate and containing a further step in which the composition applied to the substrate in the presence of Moisture is cured by crosslinking of the silane-functional prepolymer. It is inventively preferred if the composition of the first subject of the invention prior to application to the substrate by mixing i) at least one catalyst composition containing at least one compound having at least one Hydrogenpolyfluoridanion and ii) at least one prepolymer containing at least one silane-functional prepolymer having at least one Alkoxysilangruppe will be produced. Said catalyst composition and prepolymer composition preferably contain said fluoride compound or said prepolymer, each in its own carrier. The carrier comprises at least one solvent or dispersant.

The application of the composition according to the invention of the first subject of the invention can by all the usual application methods, such as. As spraying, knife coating, brushing, pouring, dipping, watering, trickling or rolling done. In this case, the substrate to be coated can rest as such, wherein the application device or -anläge is moved. However, the substrate to be coated can also be moved, with the application system resting relative to the substrate or being moved in a suitable manner. The curing of the applied composition according to the invention can take place after a certain rest period. This rest period is used for example for the course and degassing of the paint layers or for the evaporation of volatile components such as solvents. The rest period can be supported and / or shortened by the application of elevated temperatures and / or reduced air humidity. The thermal curing of the formulation is carried out by methods such as heating in a convection oven or irradiation with IR lamps. Here, the thermal curing can also be done gradually. Another preferred curing method is near infrared (NIR) curing.

The thermal curing is carried out at a temperature of 25 ° C to 200 ° C, preferably at a temperature of 25 ° C to 100 ° C, more preferably at a temperature of 25 ° C to 80 ° C.

The time of this curing can vary between 1 min and 24 h, depending on the application and temperature, especially at temperatures <40 ° C, even longer curing times come into question.

Substrates that can be coated or glued or sealed are metal, concrete, ceramic, Hol /. Paper, textile or plastic. The application temperature is preferably <100 ° C due to the active catalyst.

Due to the reactivity of the inventive composition of the first subject of the invention, it is preferable to store said catalyst and said silane-functional prepolymer separately from each other. A further subject of the invention is therefore a kit-of-parts comprising in a first container at least one compound having at least one fluoride anion (in particular a catalyst composition comprising at least one compound having at least one hydrogen polyfluoride anion and separately in a second container at least one silane-functional prepolymer having at least an alkoxysilane group (in particular a prepolymer composition comprising at least one silane-functional prepolymer having at least one alkoxysilane group). The features characterized as preferred for the first subject of the invention, in particular the said prepolymer and the said compound having at least one fluorine anion, are also preferred for the other subjects of the invention.

Examples:

The following examples serve to illustrate the present invention, but should not be construed as limiting the scope of protection.

All percentages are by weight unless stated otherwise. The NCO contents were determined titrimetrically in accordance with DI EN ISO 11909.

OH numbers were determined titrimetrically in accordance with DIN 53240-2: 2007-1 1, acid numbers according to DI 3682 5. The reported OH contents were calculated from the analytically determined OH numbers.

The flow times were determined in accordance with DIN EN ISO 2431 ("Determination of the flow time with flow cups"). The drying times (Tl, T3 and T4) were determined in accordance with DIN EN ISO 9117-5 (Drying test Part 5: Modified Bandow-Wolff process).

Competence: A small amount of gasoline was placed in a test tube and fitted with a cotton swab at the opening to form a solvent-saturated atmosphere within the test tube. The test tubes were then placed on the paint surface with the cotton swab and left there for 5 min. After wiping the gasoline, the film was tested for destruction / softening / adhesion loss. (0 = no change, 5 = film destroyed)

All visco sity measurements were made with a Physica MCR 51 rheometer from Anton Paar Germany GmbH (DE) according to DIN EN ISO 3219. Pendulum damping: The pendulum damping was measured according to DIN EN ISO 1522 on a glass plate and is determined by König.

Example 1: Preparation of STP 1

In a flask with a thermometer, KPG stirrer, reflux condenser and dropping funnel 168.0 g of hexamethylene diisocyanate (1, 0 mol) were placed under a nitrogen atmosphere at 80 ° C. At this temperature 75.3 g of 2,2,4-trimethyl-l, 3-pentanediol (97%, 0.50 mol) were added within 1 hour. After a reaction time of 4.25 hours, the NCO content had dropped to 17.3% by weight. The reaction was then cooled to 55 ° C and diluted with 287.0 g -methoxy-2-propyl acetate (MPA). 425.7 g of bis (triethoxysilylpropyl) amine (1.0 mol) were added dropwise to this reaction mixture at 50-55 ° C. within 1.5 hours. After a further 2 h stirring time at a temperature of 50-55 ° C., the NCO content was, according to IR spectroscopy, at 0. fall. This gave a 69 wt .-% polymer solution in MPA with a viscosity of 163 mPas at 23 ° C.

Example 2: Catalyst Testing with STP 1

The silane-terminated prepolymer of Example 1 was admixed with a proportion of catalyst (wt .-% with respect to the amount of STP) and geräkelt with a 120 μηι doctor blade on a dry glass plate. Optionally, the silane-terminated prepolymer was further diluted with solvent 1-methoxypropyl-2-acetate. The glass plate was stored in a climatic chamber at 23 ° C and 50% relative humidity. After the times listed in Table 1 below, the coating is tested for curing. For this purpose, the hardness was examined with a pendulum damping device (according to König). A slow pendulum damping in seconds, d. H. a high value in seconds means progressive hardening of the silane.

The following catalysts were used:

Catalyst 1: Tetrabutylammonium hydrogen difluoride 70% in isopropanol Catalyst 2: Tetrabutlyammonium hydrogen difluoride 70% in 2-ethylhexanol

Catalyst 3: Tetrabutylammonium hydrogen difluoride (50% in methylene chloride, Sigma Aldrich)

Table 1: Hardening of the STP 1 of Example 1 at 23 ° C and 50% relative humidity with different catalysts

Example 3: Preparation of STP 2 In a flask with thermometer, KPC i stirrer. Reflux cooler and dropping funnel were under

Nitrogen atmosphere at 85 ° C 222.3 g of isophorone diisocyanate (1, 0 mol) submitted. 67.7 g of 2,2,4-trimethyl-1,3-pentanediol (97% pure, 0.45 mol) and 2 l of Desmophen VP LS 2328 (polyester polyol with equivalent weight 215 ) (0.05 mol). After a reaction time of 2 hours at 85 ° C and 6 hours at 103 ° C was the NCO content dropped to 13.4 wt .-%. The reaction was then cooled to 50 ° C and diluted with 315.0 g of 1-methoxy-2-propyl acetate (MPA). 425.7 g of bis (triethoxysilylpropyl) amine (1.0 mol) were added dropwise to this reaction mixture at 50-55 ° C. within 1.5 hours. After a further 1 h stirring time at a temperature of 50-55 ° C, the NCO content had fallen to 0 according to I R spectroscopy. This gave a 69 wt .-% polymer solution in MPA with a

Viscosity of 420 mPas at 23 ° C.

Example 4: Catalyst Testing with STP 2

The silane-terminated prepolymer of Example 2 was admixed with a proportion of catalyst (wt .-% with respect to the amount of STP) and with a 120 μιη doctor on a dry glass plate geräkelt. Optionally, the silane-terminated prepolymer was further diluted with solvent 1-methoxypropyl-2-acetate. The glass plate was stored in a climatic chamber at 23 ° C and 50% relative humidity. After the times given in Table 1 below, the coating was tested for cure. For this purpose, the hardness was examined with a pendulum damping device (according to König). A slow pendulum damping in seconds, d. H. a high value in seconds means progressive hardening of the silane.

Catalyst 1: Tetrabutylphosphonium hydrogen difluoride 70% in isopropanol (inventive)

Catalyst 2: piperidinium 1-spiro-1'-pyrrolidinium hydrogen difluoride in 2-ethylhexanol (inventive)

Catalyst 3: Tetrabutylphosphonium hydrogen difluoride 70% in 2-ethylhexanol (inventive) Catalyst 4: Tetrabutylammonium hydrogen difluoride (50% in methylene chloride, Sigma Aldrich)

(Inventive)

Catalyst 5: T etrabutylammonium fluoride (1 M in tetrahydrofuran, Sigma Aldrich) (comparative)

Table 2: Hardening of the STP 2 of Example 2 at 23 ° C and 50% relative humidity with different catalysts

Catalyst STP conc. Cat pendulum hardness Pendulum hardness Pendulum hardness

(Wt .-%) in concentrate. (s) after 1 h (s) after 5 h (s) after 24

MPA (%) h

Catalyst 1 30 0.5 21 69 124

Catalyst 2 30 1, 0 18 5 119

Catalyst 3 30 0.5 32 99 159

Catalyst 4: 30 0.5 18 59 131

Catalyst 5: 30 2.0 10 32 89 The inventive catalysts 1 -4 based on the Hydrogengendifluoridanions show a much higher catalytic activity than the Fluoridanion 5. The achieved pendulum hardness of the coatings are with the inventive Hydrogengendifluoriden significantly higher than those of the fluoride anion.

Example 5: Preparation of STP 3

In a flask equipped with a thermometer, KPG stirrer, reflux condenser and dropping funnel, 255.2 g of isophorone diisocyanate (1.15 mol) were initially introduced at 83 ° C. under a nitrogen atmosphere. At this temperature 98.55 g of 2,2,4-trimethyl-1, 3-pentanediol (97%, 0.675 mol) were added within 1 hour. After a reaction time of 4 hours at 83 ° C, 108 g of MPA were added, after a further 14 h stirring time at 83 ° C, the NCO content had dropped to 8.5 wt .-%. The reaction was then cooled to 50 ° C and diluted with 216.0 g of 1-methoxy-2-propyl acetate (MPA). 402.7 g of bis (triethoxysilylpropyl) amine (0.946 mol) were added dropwise to this reaction mixture at 50 ° C. over a period of 1 hour. After a further 3 h stirring time at a temperature of 50 ° C, the NCO content had dropped to 0 according to IR spectroscopy. This gave a 70 wt .-% polymer solution in MPA with a viscosity of 1 140 mPas at 23 ° C.

Example 6: Preparation of STP 4

In a flask equipped with a thermometer, KPG stirrer, reflux condenser and dropping funnel, 222.3 g of isophorone diisocyanate (1.0 mol) were initially introduced at 83 ° C. under a nitrogen atmosphere. At this temperature 73 g of 2,2,4-trimethyl-1, 3-pentanediol (97%, 0.5 mol) were added within 1 hour. After a reaction time of 4 hours at 83 ° C, 102.7 g of MPA were added, after another 16.75 h stirring time at 83 ° C, the NCO content had dropped to 10.5 wt .-%. The reaction was then cooled to 55 ° C and diluted with 102.7 g of 1-methoxy-2-propyl acetate (MPA). 383.14 g of bis (triethoxysilylpropyl) amine (0.9 mol) and 39.72 g of N- (3-triethoxysilylpropyl) aspartaric acid ethyl ester (prepared according to DE 4237468, Example 1) were added to this reaction mixture at 50C within 50 minutes. dropwise. After another 2.5 hours of stirring at a temperature of 55 ° C, the NCO content had dropped to 0 according to IR spectroscopy. The batch was then diluted with a further 102.7 g of MPA. This gave a 65 wt .-% polymer solution in MPA with a viscosity of 180 mPas at 23 ° C.

Example 7: Preparation of STP 5

In a flask equipped with a thermometer, KPG stirrer, reflux condenser and dropping funnel, 222.3 g of isophorone diisocyanate (1.0 mol) were initially introduced at 84 ° C. under a nitrogen atmosphere. At this temperature, 60.2 g of 2,2,4-trimethyl-l, 3-pentanediol (97%, 0.40 mol) and 43.0 g Desmophen VP LS 2328 (equivalent weight 215 polyester polyol) (0.1 mol). After a reaction time of 3.5 hours at 84 ° C and 4.25 hours at 100 ° C, the NCO content had dropped to 12.8 wt .-%. The reaction was then cooled to 50 ° C and diluted with 321.0 g of 1-methoxypropyl 2-acetate (MPA). 425.7 g of bis (triethoxysilylpropyl) amine (1.0 mol) were added dropwise to this reaction mixture at 50 ° C. over a period of 1 hour. After a further 1 h of stirring time at a temperature of 50 ° C., the NCO content had fallen to 0 according to IR spectroscopy. This gave a 69 wt .-% polymer solution in MPA with a viscosity of 378 mPas at 23 ° C.

EXAMPLE 8 Preparation of STP 6 222.3 g of isophorone diisocyanate (1.0 mol) were initially introduced into a flask with thermometer, KPG stirrer, reflux condenser and dropping funnel under nitrogen atmosphere at 83.degree. At this temperature 75.3 g of 2,2,4-trimethyl-l, 3-pentanediol (97%, 0.5 mol) were added within 1 hour. After a reaction time of 3.25 hours at 84 ° C and 6 hours at 104 ° C, the NCO content had dropped to 14.1 wt .-%. The reaction was then cooled to 50 ° C and diluted with 309.0 g of 1-methoxypropyl 2-acetate (MPA). To this reaction mixture 425.7 g of bis (tri ethoxysilylpropyl) amine (1, 0 mol) were added dropwise at 50 ° C within 1 hour. After a further 2 h of stirring at a temperature of 50 ° C., the NCO content had fallen to 0 according to IR spectroscopy. This gave a 69 wt .-% polymer solution in MPA with a viscosity of 308 mPas at 23 ° C. Example 9: Preparation of STP 7

In a flask equipped with a thermometer, KPG stirrer, reflux condenser and dropping funnel, 222.3 g of isophorone diisocyanate (1.0 mol) were initially introduced at 85 ° C. under a nitrogen atmosphere. At this temperature, 73 g of 2,2,4-trimethyl-1, 3-pentanediol (97%, 0.5 mol) were added within 1 hour. After a reaction time of 1.25 hours at 83 ° C and 8 hours at 103 ° C, the NCO content had dropped to 14.3 wt .-%. The reaction was then cooled to 5 ° C and diluted with 297.0 g of 1-methoxypropyl 2-acetate (MPA). 401 g of N- (3-triethoxysilylpropyl) aspartic acid diethyl ester (prepared according to DE 4237468 Example 1) (1.0 mol) were added dropwise to this reaction mixture at 55 ° C. within 1 hour. After a further 3.5 h stirring time at a temperature of 5 ° C, the NCO content had dropped to 0 according to IR spectroscopy. This gave a 69 wt .-% polymer solution in MPA with a viscosity of 912 mPas at 23 ° C.

Example 10: Preparation of STP 8

In a flask with thermometer, KPG stirrer, reflux condenser and dropping funnel 222.3 g of isophorone diisocyanate (1, 0 mol) were placed under nitrogen atmosphere at 84 ° C. At this temperature In the course of 1 hour, 52.7 g of 2,2,4-trimethyl-1,3-pentanediol (97%, 0.35 mol) and 64.5 g of Desmophen VP LS 2328 (equivalent weight polyester polyol 215) (0 , 15 mol) was added. After a reaction time of 3 hours at 84 ° C and 5.25 hours at 104 ° C, the NCO content had dropped to 12.0 wt .-%. The reaction was then cooled to 55 ° C and diluted with 328.0 g of 1-methoxypropyl 2-acetate (MPA). 425.7 g of bis (triethoxysilylpropyl) amine (1.0 mol) were added dropwise to this reaction mixture at 55 ° C. over a period of 1.5 hours. After a further 1 h of stirring time at a temperature of 50 ° C., the NCO content had fallen to 0 according to I R spectroscopy. This gave a 68 wt .-% polymer solution in MPA with a viscosity of 397 mPas at 23 ° C. Example 1 1: Preparation of STP 9

In a flask with thermometer, KPG stirrer, reflux condenser and dropping funnel, a mixture of 97.0 g of trimerized hexamethylene-1,6-diisocyanate (Desmodur N 3300, Covestro, Leverkusen, solvent-free) was heated at 55 ° C. under a nitrogen atmosphere. and 128 gl -methoxy-2-propyl acetate. 200.0 g of N- (3-triethoxysilylpropyl) aspartic acid diethyl ester (prepared according to DE 4237468 Example 1) were added dropwise at this temperature over the course of 50 minutes and the mixture was stirred at this temperature for 3.5 hours. After this time, the reaction was complete because no more NCO groups could be detected by IR spectroscopy. This gave a 79% polymer solution in MPA with a viscosity of 1710 mPas at 23 ° C.

Example 12: Testing of Catalyst 1 of Example 4 with Various STPs The silane-terminated prepolymers of Example 3-8 were diluted, if necessary, with MPA to a polymer content of 70% by weight, then with a proportion of catalyst 1 (% by weight in%) Reference to the amount of ST) and laced with a 120 μιη squeegee on a dry glass plate. Optionally, the silane-terminated prepolymer was further diluted with solvent 1 -methoxypropyl-2-acetate. The glass plate was stored in a climatic chamber at 23 ° C and 50% relative humidity. After the times given in Table 1 below, the coating was tested for cure. The hardness was examined with a pendulum damping device (König). A slow pendulum damping in seconds, ie a high value in seconds, means a progressive hardening of the silane. Table 3: Testing STPs 3-8 with Catalyst 1

Example 13:

Paint technological test of STP 4 (see Example 6) in a refine clearcoat. The STP 4 as described in Table 4 with the catalyst Lupragen ^® N 700 (chemical identity: DHU) as compared with Catalyst 1 of Example 4 and mixed butyl acetate. This mixture is latticed on dry glass plates (wet s chichtdi cke about 100 μηι, dry film thickness about 50 μηι). Part of the glass plates is stored directly at 24 ° C and 48% relative humidity and examined the drying behavior. The other part of the glass plates is first dried at 60 ° C. for 30 minutes and then stored at 24 ° C. and 48% relative atmospheric humidity. All results are listed in Table 4 below.

Table 4:

The results show that the new catalyst (Hydrogendifluoridbasiert) is much more active than the commercial Lupragen ^® N 700 (chemical identity: DHU). The different drying stages Tl T4 are achieved at room temperature (RT) by DHU within 30-180 min, for the hydrogen difluoride catalyst within max. 10 mins. Drying at elevated temperature leads to drying in the case of the DHU within 2 h (T4). The hydrogen difluoride catalyst leads to such accelerated hardening that the coating is almost instantaneously crosslinked and dry.

Claims

claims

1. Composition, in particular for bonding, sealing or coating, containing

at least one silane-functional prepolymer having at least one alkoxy silane group; and

at least one compound having at least one hydrogen polyfluoride anion.

2. The composition according to claim 1, characterized in that silane-functionalized prepolymers are selected from at least one prepolymer from the list, which is formed from polyurethanes having at least one alkoxysilane, polymeric Polyiso- eyanaten with at least one alkoxysilane, polymeric polyols having at least one alkoxysilane, polyether polyols with at least one alkoxysilane group, polyester polyols having at least one alkoxysilane group, polycarbonate polyols having at least one alkoxysilane group, polyacrylate polyols having at least one alkoxysilane group, polymethacrylate polyols having at least one alkoxysilane group and polyurethane polyols having at least one alkoxysilane group. 3. Composition according to one of the preceding claims, characterized in that the silane-functional prepolymer having at least one alkoxysilane has a number average molecular weight Mn of at most 20,000 g / mol, preferably at most 15,000 g / mol, more preferably at most 10,000 g / mol.

4. Composition according to one of the preceding claims, characterized in that the silane-functional prepolymer contains at least one alkoxysilane group (preferably at least two alkoxysilane groups) of the general formula (I),

* ^™ R ³ -Si (R ¹⁾ _3-(OR ²⁾ _{a (I)} wherein

R ^! is an alkyl group having 1 to 8 C atoms; R "is an alkyl group having 2 to 12 C atoms;

R ^'is a linear or branched, optionally cyclic, alkylene group having 2 to 12 C atoms, optionally with aromatic moieties, and optionally with one or more heteroatoms, in particular propane-l, 3-diyl; and a is a value of 1, 2 or 3. Composition according to any one of the preceding claims, characterized in that the alkoxy radicals of the alkoxysilane groups of the silane-functional prepolymer are methoxy and / or ethoxy groups, in particular ethoxy groups.

Composition according to one of the preceding claims, characterized in that in each case an alkoxysilane group binds at the terminus of the silane-functional prepolymer.

Composition according to any one of the preceding claims, characterized in that the compound containing at least one fluoride anion is chosen from at least one compound of formula (II)

{M [n F ^~ * m (HF)]} (II) where

M is an equivalent of one or more cations carrying a charge number of n as a cationic charge and causing the electroneutrality of the compound of formula (II), n is 1 and m is a number from 1 to 5.

Composition according to Claim 7, characterized in that the compound containing at least one fluoride anion contains an n-fold cation M, preferably n = 1 and m = 1.

Composition according to any one of Claims 7 or 8, characterized in that the compound having at least one hydrogen polyfluoride anion has a structure of the indicated general formula (II) where n = 1 and m = 1 and the cation M is selected from alkali metal ions, tetraalkylammonium or tetraalkylphosphonium ions or mixtures thereof.

Composition according to Claim 9, characterized in that M is preferably a tetraalkylammonium or tetraalkylphosphonium or piperidinium-1-spiro-1'-pyrrolidinium ion, in particular a tetrabutylammonium or a tetrabutylphosphonium ion.

11. The composition according to any one of claims 7 to 10, characterized in that the alkyl groups of the cation M independently of one another linear or branched (and optionally cyclic) alkylene groups containing from 2 to 12 carbon atoms.

12. The composition according to any one of the preceding claims, characterized in that the total amount of the compound with at least one Hydrogenpolyfluoridanion based on the total weight of the composition 0.1 to 10 wt .-%, preferably 0.2 to 5 wt .-%, particularly preferably 0.2 to 3 wt .-%, is. 13. Use of a composition according to one of claims 1 to 12 as a coating, adhesive or sealant.

14. Use of a compound having at least one hydrogen polyfluoride anion for crosslinking of alkoxysilane-containing, in particular alkoxysilane-terminated, prepolymers with moisture. 15. A method of bonding, sealing or coating a substrate containing a

A step of applying a composition of claims 1 to 12 to a substrate and comprising a further step of curing the composition applied to the substrate in the presence of moisture by cross-linking the silane-functional prepolymer.