EP1539863A1

EP1539863A1 - Organopolysiloxanes and the use thereof in substances that can be cross-linked at room temperature

Info

Publication number: EP1539863A1
Application number: EP03797266A
Authority: EP
Inventors: Wolfgang Ziche; Uwe Scheim
Original assignee: Wacker Chemie AG
Current assignee: Wacker Chemie AG
Priority date: 2002-09-12
Filing date: 2003-09-04
Publication date: 2005-06-15
Also published as: DE10242415A1; CN1681870A; WO2004026944A1; US20050272895A1

Abstract

The invention relates to organopolysiloxanes containing at least one unit of formula (I) R2SiO2/2, at least one unit of formula (II) (R<5>O)R2SiO1/2, and at least one unit of formula (III) (R<1>R<2>N-CR<10>2-)RSiO2/2, whereby the radicals and indices have the meanings as cited in Claim 1. The invention also relates to the production of these organopolysiloxanes and to their use in substances that can be cross-linked at room temperature, particularly in those that cross-link while alcohols are separated.

Description

Organopolysiloxanes and their use in masses that can be crosslinked at room temperature

The invention relates to organopolysiloxanes containing nitrogen-containing residues, their production and their use in compositions which can be crosslinked at room temperature, in particular those which crosslink with the elimination of alcohols.

Siloxane-based polymers for RTV compositions are generally known, such as alkoxysilylalkylene termini (see e.g. US Pat. No. 6,037,434) or alkoxysilyl termini (see e.g. EP-A 1 006 146). For economic and technical reasons, there is only a limited range of polymer viscosities available for the production of RTV rubbers. For low-module sealants, however, higher-viscosity polymers are in demand, which should preferably be produced from standard polymers in the course of the manufacture of RTV compositions.

To increase the viscosity of the polysiloxanes and thus to lower the tension value of RTV rubbers made therefrom, longer polymers can be produced from shorter ones by chain extension. It is known that difunctional silanes or siloxanes can be used for this, which should have a sufficiently high reactivity. For example, US Pat. No. 5,110,967 describes Si-N heterocyclic silanes which, however, require that special crosslinking agents are required when formulating RTV compositions. Compounds such as bisacetamidosilanes (see, for example, US Pat. No. 5,290,826), bisacetoxysilanes (see, for example, US Pat. No. 842,586) or bisaminosilanes (see, for example, EP-A 74 001) release harmful or corrosive cleavage products during vulcanization. Bisacetoxysilanes also require the addition of amine compounds (see, for example, US Pat. No. 842,586). Alcohol is therefore very often preferred as a cleavage product, with a quick reaction with silanol-terminated Siloxanes the dialkoxysilanes or siloxanes described in US Pat. Nos. 5,300,612 and 5,470,934 are generally unsuitable. If aminomethyldialkoxymethylsilanes are used, there is a rapid reaction with polysiloxanes, but the resulting polymer is also degraded again when used in RTV compositions in the presence of active hydrogen-containing substances, such as alcohol, which are always present. RTV materials damaged in this way usually no longer vulcanize.

The invention relates to organopolysiloxanes containing at least one unit of the formula ₂ Si0 _2/2 (I), at least one unit of the formula

(R ⁵ 0) R ₂ SiOι _{/ 2} (II) and at least one unit of the formula

(R ^ N-CR ^ a-jRSiOa / a (III), where

R can be the same or different and represents a monovalent, optionally substituted hydrocarbon radical, R ', R ³ , R ⁴ , R ⁷ , R ⁸ and R ^{9 can} each independently be the same or different and have a meaning given for R,

R ¹ and R ^{10 can} each independently be the same or different and denote hydrogen atom or have a meaning given for R,

R ^{2 represents} a radical -C (= 0) -NH-R ³ or a radical -C (= 0) (OR ⁴ ), R ^{5 can be} identical or different and hydrogen atom or a radical - (R ^' ₂ Si-R ⁶ -) _y Si (OX) _a R ⁷ ₃ -a means, X has the meaning of -C (= 0) -R ⁸ , -N = CR ⁹ ₂ or a meaning given for radical R,

R ^{6 can be the} same or different and represents a divalent, optionally substituted hydrocarbon radical, a is 1, 2 or 3 and y is 0 or 1.

In the context of the present invention, the term organopolysiloxanes is intended to encompass both polymeric, oligomeric and also di-siloxanes, in which some of the silicon atoms are also derived from groups other than oxygen, such as via -N- or -C-, can be connected.

The organopolysiloxanes according to the invention are preferably those of the formula (IV)

in which

R, R ¹ , R ² and R ^{5 have} the meanings given above, o> 1, m> 1 and n> 1, with the proviso that the individual units can be distributed as desired in the molecule.

The values for m, n and o are chosen such that the viscosity of the organopolysiloxanes of the formula (IV) according to the invention is preferably between 5,000 and 1,000,000 mPa's, particularly preferably between 20,000 and 500,000 mPa's, in particular between 50,000 and 200,000 mPa's, is based on 20 ° C. The organopolysiloxanes according to the invention are particularly preferably those of the formula (I) with a ratio of n: o of preferably> 1, particularly preferably> 50, in particular> 100.

The radicals R, R ', R ³ , R ⁴ , R ⁷ , R ⁸ and R ^{9 are} each, independently of one another, monovalent hydrocarbon radicals with 1 to 12 carbon atoms which are optionally substituted by heteroatoms such as nitrogen atom, halogen atom and oxygen atom.

Examples of radicals R, R ", R ³ , R ⁴ , R ⁷ , R ⁸ and R ⁹ are alkyl radicals, such as the methyl, ethyl, n-propyl, iso-propyl, 1-n-butyl, 2- n-butyl, iso-butyl, tert-butyl, n-pentyl, iso-pentyl, neo-pentyl, tert-pentyl, hexyl, such as the n-hexyl, heptyl, such as n-heptyl, octyl, such as the n-octyl and iso-octyl, such as the 2, 2, 4-trimethylpentyl, no-nyl, such as the n-nonyl, decyl, such as the n-decyl, and dodecyl, such as the n-dodecyl radical; cycloalkyl radicals, such as cyclopentyl, cyclohexyl, cycloheptyl and methylcyclohexyl radicals, alkenyl radicals, such as the vinyl, 5-hexenyl, cyclohexenyl, 1-propenyl, allyl, 3-butenyl and 4- Pentenyl, alkynyl, such as the ethynyl, propargyl and 1-propynyl, aryl, such as the phenyl, alkaryl, such as o-, m-, p-tolyl, and aralkyl, such as the benzyl, the α - And the ß-phenylethyl radical.

Examples of substituted radicals R, R ", R ³ , R ⁴ , R ⁷ , R ⁸ and R ⁹ are haloalkyl radicals, such as the 3, 3, 3-trifluoro-n-propyl radical, the 2, 2, 2, 2 ', 2 ", 2" -hexafluoro-isopropyl radical, the heptafluoroisopropyl radical and haloaryl radicals, such as the o-, m- and p-chlorophenyl radical, and all for R, R ', R ³ , R ⁴ , R ⁷ , R ⁸ and R ⁹ radicals mentioned above which are linked to mercapto groups, epoxy-functional groups, carboxy groups, keto groups, enamine groups, amino groups, Pen, aminoethylamino groups, iso-cyanato groups, aryloxy groups, acryloxy groups, methacryloxy groups, hydroxyl groups and halogen groups can be substituted.

The radical R is particularly preferably an alkyl radical having 1 to 6 carbon atoms, in particular the methyl radical.

The radical R 'is particularly preferably an alkyl radical having 1 to 6 carbon atoms, in particular the methyl radical.

The R ³ radical is particularly preferably alkyl or aryl radicals which are optionally substituted by divalent radicals of the formula -NH-C (= 0) -, in particular alkyl radicals having 1 to 12 carbon atoms.

The radical R ⁴ is particularly preferably an alkyl radical having 1 to 6 carbon atoms, in particular the methyl and the ethyl radical.

The radical R ⁷ is particularly preferably an alkyl radical having 1 to 6 carbon atoms, in particular the methyl radical.

The radical R ⁸ is particularly preferably an alkyl radical having 1 to 6 carbon atoms, in particular the methyl radical.

The R ⁹ radical is particularly preferably an alkyl radical having 1 to 6 carbon atoms, in particular the methyl or ethyl radical.

The radical R ¹⁰ is particularly preferably a hydrogen atom. The radical R ¹ is preferably a radical specified for R above, particularly preferably alkyl or aralkyl radicals having 1 to 12 carbon atoms, in particular the cyclohexyl, methyl or ethyl radical.

The radical R ² is preferably the radical -C (= 0) -NH-R ³ with R ³ having the meaning given above, particularly preferably alkyl radicals having 1 to 6 carbon atoms.

The radical R ^s is preferably divalent hydrocarbon radicals with 1 to 12 carbon atoms, optionally substituted with heteroatoms such as nitrogen atom, halogen atom and oxygen atom.

Examples of divalent radicals R ⁶ are alkylene radicals, such as methylene, ethylene, n-propylene, iso-propylene, n-butylene, iso-butylene, tert. -Butylene, n-pentylene, isopentylene, neopentylene, tert. Pentylene radical, hexylene radicals, such as the n-hexylene radical, heptylene radicals, such as the n-heptylene radical, octylene radicals, such as the n-octylene radical and iso-octylene radicals, such as the 2,2,4-trimethylpentylene radical, nonylene radicals, such as the n -Nonylene residue, decylene residues, such as the n-decylene residue, dodecylene residues, such as the n-dodecylene residue; Alkenylene residues, such as the vinylene and allylene residues; Cycloalkylene radicals, such as cyclopentylene, cyclohexylene, cycloheptylene radicals and methylcyclohexylene radicals; Arylene radicals, such as the phenylene and naphthylene radicals; Alkarylene residues, such as o-, m-, p-tolylene residues, xylylene residues and ethylphenylene residues; Aralkylene residues, such as the benzylene residue, the α- and the β-phenylethylene residue.

The radical R ⁶ is particularly preferably an ethylene or propylene radical, in particular the ethylene radical.

Y is preferably 0. A preferably has the value 2.

X preferably has a meaning given for the radical R and -N = CR ⁹ ₂ , the methyl radical being particularly preferred.

The radical R ⁵ is particularly preferably alkoxysilyl groups and hydrogen atom, in particular alkoxysilyl radicals.

Examples of the organopolysiloxanes according to the invention are HO- (Me ₂ SiO) 500-SiMe [CH ₂ -NCy- (C = 0) NHCy] - (OSiMe ₂ ) soo-OH, (MeO) ₂ MeSi-0- (Me ₂ SiO ) ₆₅₀ -SiMe [CH ₂ -NCy- (C = 0) NHCy] - (OSiMe ₂ ) eso-O- SiMe (0Me) ₂ , HO- (Me ₂ SiO) ₅₀₀ - {SiMe [CH ₂ -NCy- ( C = O) NHCy] - (OSiMe ₂ ) ₅₀₀ -O} ₃ H and

(MeO) ₂ MeSi-0- (Me ₂ SiO) 1000- {SiMe [CH ₂ -NCy- (C = 0) NHCy] - (OSiMe ₂ ) ιooo ~ 0} ₂ -SiMe (OMe) ₂ , where Cy for Cyclohexyl and Me stands for methyl radical.

The organopolysiloxanes according to the invention have the advantage that they have high stability with regard to degradation during storage.

Furthermore, the organopolysiloxanes according to the invention have the advantage that they can be used universally in condensation-crosslinking compositions without polymer degradation and thus vulcanization disorders occurring.

The organopolysiloxanes according to the invention can be prepared by any process known in organosilicon chemistry.

According to a preferred procedure, in a first step Organopolysiloxanes terminated with hydroxyl groups with silanes of the formula

R ¹ HN-CH ₂ -SiR (OR ¹¹ ) ₂ (V)

and / or their partial hydrolyzates, where R and R ^{1 have} one of the meanings mentioned above and R ^{11 can be the} same or different and have a meaning given for R, and in a second step the amino groups of the reaction product obtained in the first step with compounds , selected from isocyanates, reactive isocyanate derivatives and reactive carboxylic acid derivatives, such as, for example, carboxylic acid anhydrides or carboxylic acid chlorides, converted to urea groups or carbamate groups.

If further branching of the organopolysiloxanes according to the invention is desired, oligo-functional isocyanates, for example, can also be used in the second step of the process according to the invention, so that several siloxane polymers, for example of the type of formula (I), are linked via radical R ³ .

According to a particularly preferred procedure, organopolysiloxanes terminated with hydroxyl groups are silanes of the formula in a first step

R ¹ HN-CH ₂ -SiR (OR ¹¹ ) ₂ (V)

and / or their partial hydrolyzates, where R and R ^{1 have} one of the meanings given above and R ^{11 can be} identical or different and has a meaning given for R, implemented and in a second step the amino groups of the reaction product obtained in the first stage with isocyanates converted to urea groups.

If desired, the organopolysiloxanes produced according to the invention can finally be treated in a third step with organosilicon compounds, such as, for example, silanes of the formula Si (OX) _a -R ⁷ 4- _a - (VI), by customary methods which are known to the person skilled in the xanchemie are known, are endblocked, where X and R ^{7 have} the meanings given above and a is 2, 3 or 4.

Another object of the present invention is a process for the preparation of the organopolysiloxanes according to the invention, characterized in that in a first step organopolysiloxanes terminated with hydroxyl groups with silanes of the formula

R ¹ HN-CH ₂ -SiR (OR ¹¹ ) ₂ (V)

and / or their partial hydrolyzates, where R and R ^{1 have} one of the meanings mentioned above and R ^{11 can be the} same or different and have a meaning given for R, are reacted in a second step with the amino groups of the reaction product obtained in the first step Compounds selected from isocyanates, reactive isocyanate derivatives and reactive carboxylic acid derivatives are converted to urea groups or carbamate groups and, if appropriate, in a third step the organopolysiloxanes obtained in the second step are end-blocked with silanes of the formula Si (OX) _a -R ⁷ 4- _a - (VI) where X and R ^{7 have} the meanings given above and a 'is 2, 3 or 4.

Examples of the silanes of the formula (V) used in the process according to the invention are CyHN-CH ₂ -Si (CH ₃ ) (OCH ₂ CH ₃ ) ₂ , C ₆ H ₅ -CH ₂ - HN-CH ₂ -Si (CH ₃ ) (OCH ₃ ) ₂ and (H ₃ C-CH ₂ ) HN-CH ₂ -Si (CH ₃ ) (OCH ₂ CH ₃ ) ₂ , where Cy is cyclohexyl.

In the first step of the process according to the invention, silanes of the formula (V) are used in amounts such that the molar Si — OH / OR ¹¹ ratio is preferably greater than or equal to 1.

Examples of isocyanates which can be used in the second step of the process according to the invention are cyclohexyl isocyanate, isophorone diisocyanate or hexamethylene diisocyanate.

Examples of reactive isocyanate derivatives which can be used in the second step of the process according to the invention are the reaction products of the abovementioned. Isocyanates with phenol or caprolactam.

Examples of carboxylic acid derivatives which can be used in the second step of the process according to the invention are acetic anhydride and acetyl chloride.

If isocyanates are used in the second step of the process according to the invention, they are preferably molar amounts of 100 to 120%, based on the silanes of the formula (V) used.

If carboxylic acid derivatives are used in the second step of the process according to the invention, it is preferred by molar amounts of 100-130%, based on the silanes of the formula (V) used.

If the third step of the process according to the invention is carried out, silanes of the formula (VI) are preferably used in amounts of 1 to 5 parts by weight, based on 100 parts by weight of the hydroxy-terminated polysiloxane used.

The components used in the method according to the invention can each be a type of such a component as well as a mixture of at least two types of a respective component.

The process according to the invention is carried out at temperatures of preferably 5 to 100 ° C., particularly preferably at room temperature, that is to say about 20 ° C., and a pressure of the surrounding atmosphere, that is to say about 900 to 1100 hPa.

The individual steps of the process according to the invention can be carried out separately or as a so-called one-pot reaction in a reaction vessel.

During the reaction according to the invention, R ^{1: L} -OH is formed, which can remain in the reaction mass or can be removed by known methods, where R ^{11 has} the meaning given above.

Overall, this results in a production process which only includes rapid reactions, so that the process according to the invention can be carried out either continuously or batchwise. The process according to the invention has the advantage that it can be carried out quickly and easily, with readily available raw materials being used as starting materials.

A particular advantage of the method according to the invention is that it can be carried out as a one-pot reaction (or successive reaction in the case of continuous production), since no deactivation of any additives or preparation of the organopolysiloxane produced is necessary after one of the substeps.

Another advantage of the process according to the invention is that the organopolysiloxanes produced can be used directly, e.g. in the production of RTV masses.

The organopolysiloxanes according to the invention or produced according to the invention can be used for all purposes for which organopolysiloxanes have also been used hitherto. They are particularly suitable for the production of masses which can be crosslinked at room temperature.

The present invention furthermore relates to compositions which can be crosslinked by condensation reaction, characterized in that they contain organopolysiloxanes according to the invention or prepared according to the invention.

In addition to the organopolysiloxanes according to the invention, the compositions according to the invention can contain all the components which have hitherto also been used to produce organopolysiloxane compositions which can be crosslinked at room temperature, so-called RTV compositions. The hydrolyzable groups, which may have the organosilicon compounds used, which are involved in the crosslinking reaction, can be any groups, such as acetyls. oxy, oximato and organyloxy groups, such as ethoxy radicals, alkoxythoxy radicals and methoxy radicals, these preferably being one-component compositions which can be crosslinked by organyloxy groups at room temperature.

Examples of components which can be used in the preparation of the RTV compositions according to the invention are condensation catalysts, reinforcing fillers, non-reinforcing fillers, pigments, soluble dyes, fragrances, plasticizers, such as dimethylpolysiloxanes or phosphoric acid esters which are liquid at room temperature and blocked by trimethylsiloxy groups , Fungicides, resinous organopolysiloxanes, including those made from (CH ₃ ) ₃ SiOι _{/ 2} - and Si0 _4/2 units, purely organic resins, such as homopolymers or copolymers of acrylonitrile, styrene, vinyl chloride or propylene, such purely organic resins, in particular copolymers of styrene and n-butyl acrylate, in the presence of diorganopolysiloxane each having an Si-bonded hydroxyl group in the terminal units, which may have been produced by polymerizing the monomers mentioned by means of free radicals, corrosion inhibitors, polyglycols which are esterified and / od it can be etherified, oxidation inhibitors, heat stabilizers, solvents, agents for influencing the electrical properties, such as conductive carbon black, flame retardants, light stabilizers and agents for prolonging the skin formation time, such as silanes with SiC-bonded mercaptoalkyl residues, and cell-generating agents, for example azodicarbonamide , Adhesion promoters, preferably amino-alkyl-functional silanes such as γ-aminopropyltriethoxysilane, can also be added.

Condensation catalysts are preferably used to prepare the compositions according to the invention. It can be any condensation catalysts, which so far in masses that can be stored in the absence of water and that have been produced to give elastomers when water is admitted at room temperature.

Examples of such condensation catalysts are organic compounds of tin, zinc, zirconium, titanium and aluminum. Preferred among these condensation catalysts are butyl titanates and organic tin compounds, such as di-n-butyltin diacetate, di-n-butyltin dilaurate and reaction products of at least two monovalent hydrocarbon radicals bonded via silicon to oxygen and optionally substituted by an alkoxy group, as hydrolyzable groups containing silane or its oligomer with diorganotin diacylate, in which reaction products all valences of the tin atoms are saturated by oxygen atoms of the group ≡SiOSn≡ or by SnC-bonded, monovalent organic radicals.

The RTV compositions according to the invention preferably contain fillers. Examples of fillers are non-reinforcing fillers, i.e. fillers with a BET surface area of up to 50 m ² / g, such as quartz, diatomaceous earth, calcium silicate, zirconium silicate, zeolites, metal oxide powders such as aluminum, titanium, iron or zinc oxides or the like Mixed oxides, barium sulfate, calcium carbonate, gypsum, silicon nitride, silicon carbide, boron nitride, glass and plastic powders, such as polyacrylonitrile powder; reinforcing fillers, ie fillers with a BET surface area of more than 50 m ² / g, such as pyrogenically produced silica, precipitated silica, carbon black, such as furnace black and acetylene black, and silicon-aluminum mixed oxides of large BET surface area; fibrous fillers such as asbestos and plastic fibers.

The fillers mentioned can be rendered hydrophobic, for example by treatment with organosilanes or organosiloxanes or with stearic acid or by etherification of hydroxyl groups to alkoxy groups. If only reinforcing silica is used as a filler, transparent RTV materials can be produced.

The components used to prepare the compositions according to the invention can each be a type of such a component and also a mixture of at least two types of a respective component.

The crosslinkable compositions according to the invention are preferably those which

(A) organopolysiloxanes according to the invention,

(B) crosslinker with at least three organyloxy radicals, (C) condensation catalysts and

(D) Contain filler.

The crosslinkable compositions according to the invention are particularly preferably those which

(A) organopolysiloxanes according to the invention,

(B) 0.01 to 5 parts by weight, based on 100 parts by weight (A), silanes with at least three alkoxy radicals and / or their partial hydrolysates, (C) 0.01 to 3 parts by weight, based on 100 parts by weight (A), condensation catalysts and

(D) 0.5 to 20 parts by weight, based on 100 parts by weight (A), of filler.

The compositions according to the invention can be produced in any manner known hitherto, for example by simply mixing the individual components, with the composition nente (A) used siloxane according to the invention can be prepared in situ.

The usual water content of the air is sufficient for the crosslinking of the RTV compositions according to the invention. The crosslinking can, if desired, also at temperatures higher or lower than room temperature, e.g. at -5 to 10 ° C or at 30 to 50 ° C. The crosslinking is preferably carried out at a pressure of the surrounding atmosphere, that is to say about 900 to 1100 hPa.

The present invention furthermore relates to moldings produced by crosslinking the compositions according to the invention.

The compositions according to the invention can be used for all purposes for which compositions which have previously been crosslinkable by condensation reaction have been used. They are therefore extremely suitable, for example, as sealing compounds for joints, including vertically running joints, and similar empty spaces, e.g. of buildings, land, water and aircraft, or as adhesives or cementing compounds, e.g. in window construction or in the manufacture of showcases, as well as for the manufacture of protective covers or rubber-elastic molded bodies and for the insulation of electrical or electronic devices. The RTV compositions according to the invention are particularly suitable as low-modulus sealing compositions for joints with possible high movement absorption.

In the examples described below, all parts with percentages are by weight unless otherwise stated. Furthermore, all viscosity data refer to a temperature of 20 ° C. Unless otherwise the examples below are given at a pressure of the surrounding atmosphere, that is at about 1000 hPa, and room temperature, that is at about 20 ° C., or at a temperature which is obtained when the reactants are combined at room temperature without additional heating or cooling, carried out.

In the following, Cy should stand for cyclohexyl radical.

example 1

500 parts by weight of a silanol-terminated dimethylpolysiloxane with a viscosity of 1000 mPa's, 500 parts by weight of a tri ethylsilyl-terminated dimethylpolysiloxane with a viscosity of 100 mPas are mixed with 4 parts by weight of a silane of the formula CyHN-CH ₂ -Si (CH ₃ ) (OCH ₂ CH ₃ ) ₂ mixed in a planetary mixer and the viscosity η ¹ determined and shown in Table 1. 2 parts by weight of cyclohexyl isocyanate are added to this polymer mixture, and after 5 minutes 30 parts by weight of methyltrimethoxysilane and 0.15 part by weight of zinc acetylacetonate are added for catalysis. The course of the viscosity is measured and shown in Table 1.

Comparative Example 1

500 parts by weight of a silanol-terminated dimethylpolysiloxane with a viscosity of 1000 mPa's, 500 parts by weight of a trimethylsilyl-terminated dimethylpolysiloxane with a viscosity of 100 mPa's are mixed with 4 parts by weight of a silane of the formula (CH ₃ CH ₂ ) ₂ N-CH ₂ -Si (CH ₃ ) (OCH ₂ CH ₃ ) ₂ mixed in a planetary mixer and the viscosity η ¹ determined and shown in Table 1. Then 30 parts by weight of methyltrimethoxysilane and 0.15 parts by weight of zinc acetylacetonate Added catalysis. The course of the viscosity is measured and shown in Table 1.

Table 1: Viscosity in mPa's

Example 2

50.0 parts by weight of a silanol-terminated dimethylpolysiloxane with a viscosity of 80,000 mPa's, 30.0 parts by weight of a trimethylsilyl-terminated dimethylpolysiloxane with a viscosity of 100 mPa's and 0.1 part by weight of a silane of the formula CyHN-CH ₂ - Si (CH ₃ ) (OCH ₂ CH ₃ ) ₂ mixed and stirred for 5 minutes. This polymer mixture is mixed with 0.07 part by weight of cyclohexyl isocyanate, and after 5 minutes 3.0 parts by weight of methyltri ethoxysilane and 0.015 part by weight of zinc acetylacetonate are added for catalysis. As soon as the silanol content is <30 ppm, 1.2 parts by weight of 3-aminopropyltrimethoxysilane, 8.5 parts by weight of a fumed silica (BET 150 πr / g) and 0.3 part by weight of a tin catalyst which is prepared by reacting di- n-butyltin diacetate and tetraethoxysilane, a stable RTV preparation. The mass thus obtained is applied in a thickness of 2 mm on a PE film and at 23 ° C / 50% rel. Humidity stored. The skin formation time is 15 minutes; the mass hardens within 24 hours and results in an elastic vulcanizate. Comparative Example 2

50.0 parts by weight of a silanol-terminated dimethylpolysiloxane with a viscosity of 80,000 mPa's, 30.0 parts by weight of a trimethylsilyl-terminated dimethylpolysiloxane with a viscosity of 100 mPa's and 0.1 part by weight of a silane of the formula (CH ₃ CH ₂ ) ₂ N-CH ₂ - Si (CH ₃ ) (OCH ₂ CH ₃ ) ₂ mixed and stirred for 5 minutes. Then 3.0 parts by weight of methyltrimethoxysilane and 0.015 parts by weight of zinc acetylacetonate are added. As soon as the silanol content is <30 ppm, 1.2 parts by weight of 3-aminopropyltrimethoxysilane, 8.5 parts by weight of a fumed silica (BET 150 m ² / g) and 0.3 part by weight of a tin catalyst which is prepared by reacting di- n-butyltin diacetate and tetraethoxysilane, a stable RTV preparation compounded. The mass is applied in a thickness of 2 mm on a PE film and at 23 ° C / 50% rel. Humidity stored. The skin formation time is 15 minutes; however, the mass does not harden and does not result in elastic vulcanizate.

Example 3

50.0 parts by weight of a silanol-terminated dimethylpolysiloxane with a viscosity of 80,000 mPa's, 30.0 parts by weight of a trimethylsilyl-terminated dimethylpolysiloxane with a viscosity of 100 mPa's and 0.1 part by weight of a silane of the formula CyHN-CH ₂ - Si (CH ₃ ) (0CH ₂ CH ₃ ) mixed and stirred for 5 minutes. This polymer mixture is mixed with 0.07 part by weight of cyclohexyl isocyanate and after 5 minutes 3.0 parts by weight of ethyl triacetoxysilane are added. A stable RTV preparation is compounded with 8.5 parts by weight of a pyrogenic silica (BET 150 m ² / g) and 0.01 parts by weight of dibutyltin diacetate. The Mass is applied in a thickness of 2 mm on a PE film and at 23 ° C / 50% rel. Humidity stored. The skin formation time is 10 minutes, the mass hardens within 24 hours and results in an elastic vulcanizate.

Claims

Godfather Tan Sayings

1 . Organopolysiloxanes containing at least one unit of the formula R ₂ Si0 _2/2 (I), at least one unit of the formula

(R ⁵ 0) R ₂ SiOι _{/ 2} (II) and at least one unit of the formula

(R ¹ R ² N-CR ¹⁰ ₂ -) ₂ RSiO / 2 (III) wherein

R ¹ and R ^{10 can} each independently be the same or different and denote hydrogen atom or have a meaning given for R, R ^{2 is} a radical -C (= 0) -NH-R ³ or a radical -C (= 0) (OR ⁴ ) means R ^{5 can be the} same or different and represents hydrogen atom or a radical - (R ' ₂ Si-R ⁶ -) _y Si (OX) _a R ⁷ ₃ _ _a ,

X has the meaning of -C (= 0) -R ⁸ , -N = CR ⁹ ₂ or has a meaning given for the radical R, R ^{6 can be} identical or different and denotes a divalent, optionally substituted hydrocarbon radical, a is 1, 2 or 3 and y is 0 or 1.

2. Organopolysiloxanes according to claim 1, characterized in that they are those of the formula (IV) acts where

R, R ¹ , R ² and R ^{5 have} the meanings given in claim 1, o> 1, m> 1 and n> 1, with the proviso that the individual units can be distributed as desired in the molecule.

3. Organopolysiloxanes according to claim 2, characterized in that the values for m, n and o in formula (IV) are chosen so that the viscosity of the organopolysiloxanes is between 5,000 and 1,000,000 mPa's, based on 20 ° C.

4. A process for the preparation of organopolysiloxanes according to one or more of claims 1 to 3, characterized in that in a first step organopolysiloxanes terminated with hydroxyl groups with silanes of the formula

R ^X HN- ^• CH, -SiR (OR ¹¹ ) ₂ (V)

and / or their partial hydrolyzates, where R and R ^{1 have} one of the meanings given above and R ^{11 can be the} same or different and have a meaning given for R, in a second step, the amino groups of the reaction product obtained in the first step with compounds selected from isocyanates, reactive isocyanate derivatives and reactive carboxylic acid derivatives are converted to urea groups or carbamate groups and, if appropriate, in a third step the organopolysiloxanes obtained in the second step with silanes of the formula Si ( OX) _a -R ⁷ ₄ - _a '(VI), where X and R ^{7 have} the meanings given above and a' is 2, 3 or 4.

5. The method according to claim 4, characterized in that in the second step, the amino groups of the reaction product obtained in the first stage are converted to urea groups with isocyanates.

6. Crosslinkable masses, characterized in that they contain organopolysiloxanes according to one or more of claims 1 to 3 or prepared according to claim 4 or 5.

7. Crosslinkable compositions according to claim 6, characterized in that they are those which

(A) organopolysiloxanes according to the invention, (B) 0.01 to 5 parts by weight, based on 100 parts by weight

(A), silanes with at least three alkoxy radicals and / or their

partial hydrolysates,

(C) 0.01 to 3 parts by weight based on 100 parts by weight

(A), condensation catalysts and (D) 0.5 to 20 parts by weight based on 100 parts by weight

(A), filler included.

8. Shaped body, produced by crosslinking the masses according to claim 6 or 7.