WO2008015120A1

WO2008015120A1 - λ5-Si - SILICATE-FUNCTIONAL PREPOLYMERS

Info

Publication number: WO2008015120A1
Application number: PCT/EP2007/057570
Authority: WO
Inventors: Christoph Briehn; Volker Stanjek; Reinhold Tacke; Simona Dragota
Original assignee: Wacker Chemie Ag
Priority date: 2006-08-01
Filing date: 2007-07-23
Publication date: 2008-02-07
Also published as: DE102006035846A1

Abstract

The invention provides moisture-curable prepolymers (A) which have at least one structural element selected from the general formulae [1] to [3], -NR2-B-SiL4 [1], =NR-B-SiL4 [2], [3], N-B-SiL4 where L is a monodentate ligand which is selected from fluorine, alcohol, carboxylic acid and hydroxime radical, L2 is a bidentate ligand which is selected from diol, amino alcohol, hydroxycarboxylic acid, aminocarboxylic acid and dicarboxylic acid radical, with the proviso that the four ligands L are capable of stabilizing the pentacoordinated silicon atom and B, and R is as defined in claim 1, where the nitrogen atom in the general formula [2], as an endocyclic nitrogen atom, is part of an aliphatic heterocycle, and the nitrogen atom in the general formula [3], as an endocyclic nitrogen atom, is part of an aromatic heterocycle.

Description

λ ^ Si-silicate-functional prepolymers

The invention relates to moisture-curable λ ^ Si silicate-functional prepolymers, processes for their preparation and polymer blends containing these prepolymers.

Prepolymers which have reactive alkoxysilyl groups have long been known and are widely used for the production of elastic sealants and adhesives in the industrial and construction sectors. In the presence of atmospheric moisture and suitable catalysts, these alkoxysilane-terminated prepolymers are already at room temperature able to condense with elimination of the alkoxy groups and formation of Si-O-Si bonds with each other. Thus, these prepolymers can be u.a. as a one-component curing in the air

Use systems that have the advantage of easy handling.

Depending on the content of alkoxysilyl groups and their structure are formed in the curing of this type of polymer mainly long-chain polymers (thermoplastics), relatively wide-meshed three-dimensional networks (elastomers) or highly crosslinked systems (thermosets).

Alkoxysilane-functional prepolymers can be composed of different building blocks. They usually have an organic backbone, ie they are composed, for example, of polyurethanes, polyethers, polyesters, polyacrylates, polyvinyl esters, ethylene-olefin copolymers, styrene-butadiene copolymers or polyolefins, as described, inter alia, in US Pat. Nos. 6,207,766 B and 3,971,751 A described. In addition, prepolymers are widely used, the backbone quite or at least in part consist of organosiloxanes, described inter alia in US 5,254,657 A.

Of central importance in the preparation of prepolymer, however, are the monomeric alkoxysilanes through which the prepolymer is provided with the alkoxysilane functions required for moisture curing. In principle, a wide variety of silanes and coupling reactions can be used, e.g. an addition of Si-H-functional alkoxysilanes to unsaturated prepolymers, a copolymerization of unsaturated organosilanes with other unsaturated monomers or a reaction of hydroxy-functional prepolymers with isocyanate-functional alkoxysilanes, as described, for example, in US Pat. No. 5,068,304.

A disadvantage of most known and currently used systems, however, is their only moderate reactivity to moisture, both in the form of atmospheric moisture and in the form of - optionally added - water. In order to achieve a sufficient curing rate even at room temperature, therefore, the addition of a catalyst is absolutely necessary. This is especially problematic because the organotin compounds usually used as catalysts are toxicologically questionable. In addition, the tin catalysts used often contain traces of highly toxic tributyltin derivatives.

Alkoxysilane-terminated prepolymers, as described, for example, in DE 101 42 050 A and DE 10 2004 059 379 A, can therefore represent a major advantage. These prepolymers are characterized in that they contain alkoxysilyl groups, the only by a methylene spacer of a Nitrogen atom are separated. As a result, these prepolymers have an extremely high reactivity towards (atmospheric moisture, so that they can be processed into prepolymer blends that can do without metal-containing catalysts, and still at room temperature with sometimes extremely short tack-free times or with very high

Cure speed. Since these prepolymers thus have an amino function in the CC position to the silyl group, they are also referred to as α-alkoxysilane-terminated prepolymers.

These CC alkoxysilane terminated prepolymers are typically prepared by a reaction of a CC aminosilane, i. an aminomethyl-functional alkoxysilane prepared with an isocyanate-functional prepolymer or an isocyanate-functional precursor of the prepolymer.

Common examples of CC aminosilanes are N-cyclohexylaminomethyltrimethoxysilane, N-cyclohexylaminomethylmethyldimethoxysilane, N-ethylaminomethyltrimethoxysilane, N-ethylaminomethylmethyldimethoxysilane, N-butylaminomethyltrimethoxysilane, N-cyclohexylaminomethyltriethoxysilane, N-cyclohexylaminomethylmethyldiethoxysilane , Piperazinomethyl- trimethoxysilane, piperazinomethyl-methyldimethoxysilane and piperazinomethyl-dimethylmethoxysilane and the corresponding ethoxysilanes.

However, all of the moisture-crosslinkable prepolymers described in the literature have in common that they have only limited storage stability in the presence of water and thus have only a very short pot life. Thus, upon entry of (air) moisture, the hydrolysis and condensation of the alkoxysilyl groups of the prepolymer leading to crosslinking of the polymer usually occurs spontaneously. This spontaneous hydrolysis and condensation of the alkoxysilyl groups is also without Addition of a catalyst usually unavoidable. The preparation of a prepolymer that is stable to water and can be activated if necessary for moisture crosslinking, has not been successful. It would be such - especially water-soluble -

Prepolymer, which is stable to (air) moisture and can be crosslinked if necessary by forming siloxane, particularly desirable because such polymers present in aqueous solution in the hardening - apart from the liberated by hydrolysis and condensation of the alkoxysilyl group - no organic Solvent would release and also possessed in water a very long pot life.

In recent years, numerous zwitterionic λ, Si silicates have been described in the literature (inter alia, Tacke, R .;

Bertermann, R .; Burschka, C; Dragota, S .; Penka, M .; Richter, I.J. Am. Chem. Soc. 2004, 126, 14493-14505). These compounds possess a pentacoordinated, formally negatively charged silicon atom and a tetracoordinated, formally positively charged nitrogen atom. Upon dissolution of most of these zwitterionic λ ^ Si silicates in water, spontaneous hydrolysis and condensation occurs with gel formation. Recently, a novel zwitterionic λ, Si silicate has been reported to possess two bidentate silicon-bonded meso-oxolane-3,4-diolato (2-) ligands (Tacke, R., Bertermann, R., Burschka, C .; Dragota, S. Angew. Chem. Int. Ed. 2005, 44, 5292-5295). This compound has a much greater stability in water without spontaneous gel formation.

It was the task of a moisture-curable

To develop prepolymer system which is stable in the presence of water or in aqueous solution and can be cured if necessary by forming a siloxane network. The invention relates to moisture-curable prepolymers (A) which have at least one structural element selected from the general formulas [1] to [3],

-NR ₂ -B-SiL ₄ [1],

= NR-B-SiL ₄ [2],

-NB-SiL ₄ [3] '

dispose, whereby

L is a monodentate ligand selected from a

L _{2 is} a bidentate ligand selected from a diol, aminoalcohol, hydroxycarboxylic acid, aminocarboxylic acid and dicarboxylic acid radical, with the proviso that the four ligands L are capable of to stabilize the pentacoordinated silicon atom,

B is a structural element (CR-L ₂ ) _m or an optionally substituted alkylene interrupted by heteroatoms,

Arylene or heteroarylene radical,

R is hydrogen or an optionally substituted hydrocarbon radical and

R! Mean hydrogen, halogens or an optionally substituted hydrocarbon radical and m can assume the values 1, 2, 3, 4 or 5, wherein the nitrogen atom in the general formula [2] as endocyclic nitrogen atom is part of an aliphatic heterocycle, and the nitrogen atom in the general Formula [3] as an endocyclic nitrogen atom is part of an aromatic heterocycle. The structural elements of the general formulas [1] to [3] are characterized in that the nitrogen atom carries a positive formal charge, and the silicon atom of the silyl fragment SiL4 carries a negative formal charge. The ligands L4 are bound to the silicon atom via the atoms F, O or N. Bidentate ligands L2 are doubled in the general formulas [1] to [3], for example, two bidentate ligands L2 are required for L4.

The prepolymers (A) are stable in the presence of water or in aqueous solution or suspension in a pH range which depends on the nature of the particular structural element of the general formulas [1] to [3] and can be modified if necessary, in particular by changing the pH pH, after hydrolysis by condensation of the silanol groups are cured.

In a preferred embodiment of the invention, L4 contains one or two bidentate ligands L2. In a particularly preferred embodiment of the invention, L4 stands for two identical bidentate ligands L2, which are derived from alkane-1,2-diols, α-hydroxycarboxylic acids, dicarboxylic acids or alkylhydroxamic acids.

The radical B is preferably a C] _, C2 ~, C3 or C4 ~ spacer or a phenylene radical. B particularly preferably represents a C] _-

Spacer. The radicals R and R ^ - are preferably hydrogen, aliphatic or aromatic hydrocarbon radicals having 1 to 10, in particular 1 to 6 carbon atoms. The radicals hydrogen, methyl, ethyl, n-propyl, cyclohexyl and phenyl are particularly preferred. m preferably assumes the values 1, 2, 3 or 4, particularly preferably the value 1. The aliphatic heterocycles which are part of the structural element of the general formula [2] are preferably optionally substituted aziridine, morpholine, pyrrolidine, piperazine and piperidine. The aromatic heterocycles which are part of the structural element of general formula [3] are preferably optionally substituted pyridine, pyrrole, imidazole, benzimidazole, indole, quinoline, benzoxazole, benzothiazole, pyrazole or triazole. If the aliphatic heterocycles which are part of the structural element of the general formula [2] or the aromatic heterocycles which are part of the structural element of the general formula [3] bear substituents, these are preferably fluorine, chlorine or C 1 - to Cg-alkyl radicals.

Another object of the invention is the preparation of prepolymers (A) by a process in which functional prepolymers (Al) having a group reactive toward F in a first stage with silanes (Sl) of the general formula [4],

FB-SiX ₃ [4],

converted into prepolymers (A2) and these are subsequently reacted by reaction with compounds (V) selected from among alcohols, carboxylic acids, diols, aminoalcohols, dicarboxylic acids, hydroxycarboxylic acids, aminocarboxylic acids,

Hydroximes into which prepolymers (A) are converted, F being a group which is reactive with respect to the functional prepolymers (Al),

X is a monovalent, optionally substituted alkoxy radical, aryloxy radical, acyloxy radical each having 1 to 10, preferably 1 to 6, carbon atoms or a halogen and B have the meanings given in the general formulas [1] to [3].

Another object of the invention is the preparation of prepolymers (A) by a process in which functional prepolymers (Al) with an opposite F-reactive group with λ ^ Si silicates (S2) of the general formula [5],

FB-SiL ₄ [5],

be implemented, where

B, F and L are those given in the general formulas [I] - [4]

Have meanings, with the proviso that in the X ^ Si silicates (S2) the structural element F-B is present in cationic form and prepared by this method

Prepolymers (A) have at least one structural element of the general formula [1] to [3].

Alternatively, prepolymers (A) can also be obtained by the silanes (Sl) of the general formula [4] or X, Si silicates (S2) of the general formula [5] by anionic, cationic or free-radical polymerization with a polymerizable monomer (M) are reacted, with the proviso that in the case of the use of silanes (Sl), the resulting prepolymers (A2) are then reacted with compounds (V) to give prepolymers (A). These methods are also the subject of the present invention.

A process for the preparation of the copolymers (A) or the polymers (A2) and a list of the suitable polymerizable monomers (M) and silanes (S1) can be found, for example, in US Pat. Nos. 5,827,922 A and EP 0 853 645 A. Preparation of the used for the polymerization λ ^ Si silicates (S2) is described in the following text.

X is preferably a halogen, a methoxy, ethoxy or acetoxy radical; X is particularly preferably a chlorine atom or a methoxy radical. Preferably, the reactive group F contains an amino, methacrylato, acrylato, epoxy, isocyanato, vinyl, carbinol, carboxyl or thiol group.

As silanes (Sl) of the general formula [4], preference is given to using chlorine- and alkoxy-functional silanes which carry isocyanato and amino groups as functional groups F. Examples of such silanes are isocyanatopropyltrimethoxysilane, isocyanatopropylmethyldimethoxysilane, isocyanatopropylphenyldimethoxysilane, isocyanatomethyltrimethoxysilane, isocyanatomethylmethyldimethoxysilane, isocyanatomethylphenyldimethoxysilane, aminopropyltrimethoxysilane, aminopropylmethyldimethoxysilane, aminopropylphenyldimethoxysilane, aminomethyltrimethoxysilane, aminomethylmethyldimethoxysilane, aminomethyl -phenyldimethoxysilan,

Cyclohexylaminomethyltrimethoxysilane, cyclohexylaminomethylmethyldimethoxysilane, cyclohexylaminomethylphenyldimethoxysilane, anilinomethyltrimethoxysilane, anilinomethylmethyldimethoxysilane, anilinomethylphenyldimethoxysilane, piperazinopropyltrimethoxysilane (Formula

[6]), piperazinopropyl-methyldimethoxysilane, piperazinopropyl-phenyldimethoxysilane, piperazinomethyl-trimethoxysilane (Formula

[7]), piperazinomethyl-methyldimethoxysilane, piperazinomethylphenyldimethoxysilane and the corresponding chloro- and ethoxysilanes. OMe

OMe

J]

As λ ^ Si-silicates (S2) of the general formula [5] preferably λ ^ Si silicates are used, which carry as functional groups F isocyanato or amino groups. A particularly preferred example of such λ ^ Si silicates is the compound [8].

The preparation of the λ ^ Si silicates (S2) of the general formula [5] is carried out starting from the silanes (Sl) of the general formula [4] by reaction with suitable compounds (V), which is a pentacoordinated (formally negatively charged) silicon atom in stabilize the general formula [5] and thus to Formation of zwitterionic structural elements of the general formula [5] are capable of.

In a preferred embodiment of the invention, the compounds (V) used are those compounds which

Contain structural elements with vicinally arranged hydroxy groups, which can bind to the silicon atom after deprotonation as chelate ligands. Examples of such compounds are monomeric, oligomeric or polymeric sugars in both acyclic and cyclic forms such as glyceraldehyde, erythrose, threose, arabinose, ribose, ribulose, glucose, fructose, galactose, sucrose, maltose, cellulose, starch and cyclodextrins, and the like their reduced and oxidized forms, ascorbic acid, ethylene glycol, propylene glycol, 2-hydroxyacetic acid, oxalic acid, lactic acid, tartaric acid, mandelic acid, citric acid, glycerol, 3,4-dihydroxyproline, tetrahydro-3,4-furanediol, 1,2-cyclohexanediol, dioxolane 3, 4-diol and catechol. Particularly preferred compounds (V) are tetrahydro-3,4-furanediol, dioxolan-3, 4-diol, fructose, sorbitol, citric acid, tartaric acid and 3,4-dihydroxyproline.

By reacting the silanes (Sl) with the compounds (V), the zwitterionic .lambda.-Si silicates (S2) of the general formula [5] are formed by cleavage of the groups X of the silyl groups SiX.sub.s of the general formula [4]. This reaction can be carried out either with or without catalyst, but the reaction is preferably carried out without catalyst. The silanes (S2) can be prepared both in an organic or aqueous solvent or in substance.

Typical syntheses of the zwitterionic λ 1 -Si-silicates of the general formula [5] are described in the literature (eg: Tacke, R .; Pülm, M .; Wagner, B. Ädv. Organomet. Chem. 1999, 44, 221-273) described. In a preferred variant of silane preparation, compound (V) is used in excess.

The functional polymers (Al) are

Polymers which are reactive towards the groups F of the silanes (SI) and λSi-silicates (S2) and generally from a polymer backbone (R) and the groups which are reactive towards the silanes (SI) and λSi-silicates (S2) (D) are constructed. Examples of suitable polymers (R) are polyorganosiloxanes, polyurethanes, polyethers, polyesters, epoxy resins, polyacrylates, polyvinyl alcohols, polyvinyl acetates, polyvinyl butyrals, polyvinyl esters, ethylene-olefin copolymers, styrene-butadiene copolymers and polyolefins. Examples of the reactive groups (D) are vinyl, hydroxy, amino, epoxy, methacrylato,

Acrylato, carboxyl, isocyanato and mercapto groups and Si-H-functional groups. The functional groups (D) in linear polymers (Al) may be terminal, lateral or terminal and laterally attached. In the case of branched polymers, the position of the functional groups (D) is arbitrary. The number of functional groups (D) in the prepolymer (Al) is preferably ≥ 1.

For the preparation of the prepolymers (A), the reactive silanes (Sl) or λ ⁵ Si-silicates (S2) through its functional group F - preferably covalently - to the functional group (D) of the prepolymer (Al) bound.

In a preferred embodiment of the invention, the synthesis of the prepolymers (A) by reaction of a vinyl-functional silane (Sl) or λ ^ Si silicate (S2) with a Si-H-functional organopolysiloxane, by reacting an amino-functional silane ( Sl) or λ ^ Si silicate (S2) with a Epoxy, methacrylato or acrylato-functional polymer, by reacting an isocyanate-functional silane (Sl) or λ ^ Si-silicate (S2) with a hydroxy-functional polymer or by reacting an amino-functional silane (Sl) or λ ^ Si silicate (S2) with an isocyanate-functional polymer, as described for example in DE 101 39 132 A. Particularly preferred is a synthesis of the prepolymers (A) by

Reaction of an amino-functional silane (S1) or λ1-5 silicate (S2) with an epoxy, methacrylate, acrylato or isocyanato-functional polyethylene glycol. In a particularly preferred embodiment of the invention, the polymers (A2) used are the alkoxysilane-terminated prepolymers described in DE 101 39 132 A, which are distinguished by containing alkoxysilyl groups which are only separated from a nitrogen atom by a methylene spacer.

In the case of using the λ ^ Si silicates (S2), the prepolymer (A) according to the invention is obtained by the reaction with the prepolymer (Al).

In the case of using the silanes (SI), a reaction with the prepolymer (Al) gives a silane-functional prepolymer (A2) which is reacted in a subsequent reaction with compounds (V) to give the prepolymer (A).

Preference is given in the synthesis of the prepolymers (A) from the λ ^ Si silicates (S2) or the preparation of the polymers (A2) from the silanes (S1), the proportions of the components (Al) and (S2) or (Al ) and (Sl) are chosen so that the ratio between the number of functional groups F of the silane (Sl) or the λ ^ Si silicate (S2) and the functional groups (D) of the polymer (Al) from 0.6 to 1.4. Particularly preferred are the functional groups F and (D) in a ratio used by 1: 1. That is to say that the polymers (A) and (A2) are preferably free of functional groups (D) after the reaction with the silanes (S1) or λ1-5 silicates (S2). In the subsequent reaction of the polymer (A2) to the prepolymer (A), the compound (V) is used in a stoichiometric ratio or an excess relative to that used for the preparation of the structural elements of the general formulas [1] to [3]. Preferably, the compound (V) is used in an excess. This is also the case by the copolymerization of silanes

(51) polymer (A2) obtained with suitable monomers (M) with respect to that for the preparation of the structural elements of the general formulas [1] to [3] in a stoichiometric ratio or an excess of compound (V). Preferably, the compound (V) is used in an excess.

If the prepolymer (A) by reaction of the polymer (Al) with the λ ^ Si silicate (S2) or by copolymerization of the λ ^ Si silicate (S2) produced with suitable monomers, can in

Following the synthesis of the prepolymer (A) - based on the

Amount of used λ ⁵ Si-silicate (S2) - <10 wt .-%, preferably ≤ 5 wt .-% of the compound (V) can be added.

As compounds (V), those for the synthesis of the λ ^ Si silicates

(52) compounds used.

By reacting the prepolymer (A2) with the compounds (V), the groups SiXβ of the silane of the general formula [4] with substitution of the radicals X in the zwitterionic

Structural elements of the general formula [1] to [3] transferred. In the case of a chlorosilyl radical (X = Cl), this substitution can be carried out with cleavage of a Si-halogen, in the case of a Alkoxysilyl (X = O-alkyl) with cleavage of a Si-O- and in the case of an alkyl or Arylsilylrestes (X = alkyl or aryl) by cleavage of a Si-C bond done. As cleavage products, in each case the corresponding protonated components are liberated during this substitution. In this case, the cleavage products can remain in the mixture or, for example, be removed by heating or under reduced pressure.

The preparation of the prepolymers (A) by reacting the functional polymers (Al) with the silanes (Sl) or the λ ^ Si silicates (S2) and in the case of the use of silanes (Sl) subsequent reaction with the compounds ( V) can be carried out in the absence of a solvent. Alternatively, the synthesis can be carried out in an organic solvent or in water. Of course, the synthesis of the prepolymers (A) can also be carried out in a mixture of different solvents. If the synthesis is carried out in a solvent, this can be removed by distillation after preparation of the prepolymer (A); Alternatively, the solvent may remain in the prepolymer (A). The synthesis of the prepolymer (A) is preferably carried out at a temperature of 0 ⁰ C to 120 ⁰ C, more preferably at a temperature of 20 ⁰ C to 100 ° C.

The preparation of the prepolymers (A) can be carried out as a one-pot reaction by simply combining the described components, it being possible to add a catalyst and / or to work at elevated temperature. Because of the sometimes relatively high exothermicity of these reactions, it may be advantageous to successively add the individual components in order to better control the amount of heat released to be able to. A separate purification or other workup of the prepolymer (A) is usually not required.

The reactions occurring in the preparation of the prepolymers (A) between the silanes (Sl) or λ ^ Si silicates (S2) and the functional prepolymers (Al) and the reaction of the polymer (A2) with compounds (V) may optionally by a catalyst can be accelerated. Suitable catalysts are the commonly used organic and inorganic heavy metal compounds, e.g. the organic ones

Tin compounds dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetylacetonate, dibutyltin diacetate or dibutyltin dioctoate, etc., in question. Furthermore, titanates, e.g. Titanium (IV) isopropylate, iron (III) compounds, e.g. Iron (III) acetylacetonate, or amines, e.g.

Triethylamine, tributylamine, 1,4-diazabicyclo [2,2,3] octane, 1,8-diazabicyclo [5.4.0] undec-7-ene, 1,6-diazabicyclo [4.3.0] non-5-ene, N, N-bis (N, N-dimethyl-2-aminoethyl) methylamine, N, N-dimethylcyclohexylamine, N, N-dimethylphenlyamine, N-ethylmorpholine, etc. are used. Also organic or inorganic Brönsted acids such as acetic acid, trifluoroacetic acid or benzoic acid, hydrochloric acid, phosphoric acid and their mono- and / or diesters, such. Butyl phosphate, (iso) propyl phosphate, dibutyl phosphate, etc., are suitable as catalysts. Of course, combinations of several catalysts can be used instead of a catalyst.

The prepolymers (A) are - depending on the nature of the present polymer backbone (R) - polymers which are soluble in conventional organic solvents and water or in mixtures of organic solvents and water and stable in storage. Shelf life means in this Context that the prepolymers (A) show no significant molecular weight and a concomitant increase in viscosity.

However, the storage stability of the prepolymers (A) is given only for one of the type of the respective structural element of the general formula [1] to [3] dependent concentration or a concentration range of Bronsted or Lewis acids or Bronstedt or Lewis bases , If this concentration range is left, a significant increase in molecular weight, a concomitant increase in viscosity and, finally, complete curing of the polymer are observed within a short time. This behavior can be explained by the fact that the zwitterionic structure of the general formula [1] to [3] by leaving the

Concentration range in which the prepolymer (A) is stable, is destabilized and as a result followed by hydrolysis and subsequent condensation of the prepolymers (A) to the cured compositions.

To cure the prepolymers (A), these can be admixed with Bronsted or Lewis acids or Bronsted or Lewis bases. These components can be added as a pure substance as well as a solution in water or an alcoholic solvent. Preferably, the Brönstedt or

Lewis acids or Bronsted or Lewis bases in amounts of 0.01 to 5 wt .-%, particularly preferably from 0.01 to 1 wt .-%, based on the weight of the prepolymers (A) added.

In a preferred embodiment of the invention, the prepolymers (A) are cured by addition of Bronsted acids. Examples of suitable acids are hydrochloric acid, acetic acid, trifluoroacetic acid and p-toluenesulfonic acid. Is that right Prepolymer (A) in aqueous solution, the curing of the polymer is preferably initiated by changing the pH. The curing of the prepolymers (A) typically takes place at a pH of ≦ 10, preferably at a pH of ≦ 8 and particularly preferably at a pH of ≦ 7.

Likewise provided by the invention are polymer blends (M) which contain the prepolymers (A). For this purpose, the prepolymers (A) can be blended with other common components (K) known to the person skilled in the art. As components (K), known auxiliaries, such as adhesion promoters, plasticizers, thixotropic agents, fungicides, flame retardants, pigments, etc. are used. Also light stabilizers, antioxidants, fillers, free-radical scavengers and other stabilizers can be added to the polymer blends (M). To produce the respective desired property profiles of both the uncrosslinked polymer blends (M) and the cured blends (M), such additives are preferred.

The polymer blends (M) containing the prepolymers (A) may also contain even small amounts of an organic solvent. This solvent serves to lower the viscosity of the uncrosslinked polymer blends (M). As a solvent, in principle, all solvents and solvent mixtures in

Consideration. Preference is given to solvents which have a solubility of 10 g of solvent in 100 g of water at 20 ^° C.

For the polymer blends (M) there are numerous different applications as adhesives and sealants, such as

Joint sealants, as a coating material as well as in the production of moldings. The polymer blends (M) can be used both in pure form as well as in the form of solutions or dispersions. The polymer blends (M) are preferably used in the form of an aqueous solution.

All the above symbols of the above formulas each have their meanings independently of each other.

Unless otherwise indicated, all amounts and percentages are by weight, all pressures are 0.10 MPa (abs.) And all temperatures are 20 ^° C.

Example 1: Synthesis of a moisture-curable prepolymer

Synthesis of the alkoxysilane-terminated polymer: To a solution of 2.00 g (9:34 mmol) of di (ethylene glycol) - diacrylate in 10 ml of toluene (18.7 mmol) piperazinomethyl-trimethoxysilane added 4.12 g, and the reaction mixture was stirred for 3 h at 20 ⁰ C. , Thereafter, the solvent was removed under reduced pressure and the remaining liquid was freed from the volatile constituents in vacuo (0.01 Torr, 1 h, 30 ⁰ C). 4.90 g (7.48 mmol, yield 80%) of a colorless, viscous oil were obtained.

OMθ

+ 2 MeO - Si - CH ₂ --N NH OMθ

OMe OMe

Synthesis of the λ, Si-Silicate-Terminated Polymer: To a solution of 1.00 g (1.53 mmol) of the alkoxysilane-terminated polymer described in the previous section in 20 ml of tetrahydrofuran was added 637 mg (6.12 mmol) of meso-oxolane-3,4-diol was added, and the resulting reaction mixture was stirred at 20 ⁰ C for 30 min. Then 40 ml of diethyl ether was added and stirred at 20 ⁰ C for 1 h. The precipitate which precipitated out was washed with diethyl ether (2 × 20 ml) and dried in vacuo (0.01 torr, 20 ° C., 3 h). This gave 1.28 g (1.46 mmol, yield 95%) of a white solid; Smp. 157 ° C (decomp.).

Example 2: Investigation of the stability and crosslinking of a moisture-curable polymer

To a solution of 158 mg (0.18 mmol) of the λSi-silated polymer described in Example 1 in 2 ml of water was added 19 mg (0.18 mmol) of meso-oxolane-3,4-diol, and the resulting mixture became stirred for 30 min at 20 ⁰ C According to 29si NMR spectroscopy, the λ ^ Si silicate-terminated polymer was stable in solution for a period of at least 8 weeks

(only minor formation of T ⁿ groups). The solution showed no gel content.

A solution of 527 mg (0.60 mmol) of the λSi-silicate-terminated polymer described in Example 1 in 10 ml of water was adjusted to pH 5 by means of concentrated hydrochloric acid. Evaporation of the solvent gave an elastomeric solid which did not redissolve in water.

Claims

claims

1. Moisture-curable prepolymers (A) which have at least one structural element selected from the general formulas [1] to [3],

-NR ₂ -B-SiL ₄ [1],

= NR-B-SiL ₄ [2],

-NB-SiL ₄ [3] '

where L is a single ligand selected from fluoro,

L _{2 is} a bidentate ligand selected from diol, aminoalcohol, hydroxycarboxylic acid, amino carboxylic acid and dicarboxylic acid, provided that the four L ligands are capable of the pentacoordinated silicon atom stabilize,

Arylene or heteroarylene radical,

R is hydrogen or an optionally substituted hydrocarbon radical and

R! Mean hydrogen, halogens or an optionally substituted hydrocarbon radical and m can assume the values 1, 2, 3, 4 or 5, wherein the nitrogen atom in the general formula [2] as endocyclic nitrogen atom is part of an aliphatic heterocycle, and the nitrogen atom in the general Formula [3] as an endocyclic nitrogen atom is part of an aromatic heterocycle.

2. Prepolymers (A) according to claim 1, in which L4 contains one or two bidentate ligands L2.

3. prepolymers (A) according to claim 1 or 2, wherein B represents a C _] _ spacer.

4. Prepolymers (A) according to claim 1 to 3, wherein the aliphatic heterocycles which are part of the structural element of the general formula [2] are selected from substituted and unsubstituted aziridine, morpholine, pyrrolidine, piperazine and piperidine.

5. prepolymers (A) according to claim 1 to 4, wherein the aromatic heterocycles which are part of the structural element of the general formula [3] are selected from substituted and unsubstituted pyridine, pyrrole, imidazole, benzimidazole, indole, quinoline, benzoxazole , Benzothiazole, pyrazole and triazole.

6. A process for the preparation of prepolymers (A), wherein the functional prepolymers (Al) having a group reactive toward F in a first stage with silanes (Sl) of the general formula [4],

FB-SiX ₃ [4],

Hydroximes into which prepolymers (A) are converted, F being a group which is reactive with respect to the functional prepolymers (Al), X is a monovalent, optionally substituted

Alkoxy, aryloxy, Acyloxyrest each having 1 to 10, preferably 1 to 6 carbon atoms or a halogen and B has the meaning given in the general formulas [1] to [3] according to claim 1.

7. A process for the preparation of prepolymers (A), wherein the functional prepolymers (Al) with an opposite F-reactive group with λ ^ Si silicates (S2) of the general formula [5],

FB-SiL ₄ [5],

be reacted, wherein B, F and L are those given in the general formulas [1] to [4] according to claim 1 and 6

Have meanings, with the proviso that in the X ^ Si silicates (S2) the structural element F-B is present in cationic form and the prepolymers prepared by this process (A) at least one structural element of the general formula [1] to [3].

8. A process for the preparation of prepolymers (A), wherein the silanes (Sl) of the general formula [4] according to claim 6 or the λ ^ Si silicates (S2) of the general formula [5] according to claim 7 by anionic, cationic or radical polymerization with a polymerizable monomer (M) are reacted, with the proviso that in the case of the use of silanes (SI), the resulting prepolymers (A2) are then reacted with compounds (V) to give prepolymers (A).

9. polymer blends (M) containing the prepolymers (A) according to claim 1 to 5.

10. Use of the polymer blends (M) according to claim 9 as adhesive and sealant and as a coating material,