EP1996638A2

EP1996638A2 - Foams containing silicon

Info

Publication number: EP1996638A2
Application number: EP07712411A
Authority: EP
Inventors: Volker Stanjek; Peter Ball; Richard Weidner; Jens Cremer
Original assignee: Wacker Chemie AG
Current assignee: Wacker Chemie AG
Priority date: 2006-03-23
Filing date: 2007-03-01
Publication date: 2008-12-03
Also published as: US20090105358A1; KR20090005033A; WO2007107435A3; WO2007107435A8; WO2007107435A2; CN101405319A; JP2009530459A; DE102006013416A1; KR101027184B1

Abstract

The invention relates to a method for producing organically modified organopolysiloxanes (S) which are foamed by means of foaming agents that are selected from water and physical foaming agents and then left to harden to form foam and has, in the agent, at least one isocyanate function per molecule. According to the invention, organopolysiloxanes (S1) comprising at least one reactive group per molecule, selected from an aminoalkyl- and a hydroxyalkyl group are reacted with polyisocyanates (J) comprising at least two isocyanate groups per molecule in the presence of a solubilizing component between the reaction partners (S1) and (J) and at least 1,05 Mol isocyanate groups are present per Mol reactive groups.

Description

Silicone-containing foams

The invention relates to a preparation process for isocyanate-functional organopolysiloxanes, to these containing foamable preparations and the foams produced therefrom.

Both pure silicone foams, as well as flexible polyurethane foams prepared from organic polyols and di- or polyisocyanates have long been known. However, both substance groups each have specific advantages and disadvantages. Although silicone foams are generally distinguished by good high and low temperature resistance and excellent flame resistance, they also have a comparatively high density and only a very moderate mechanical property profile. Polyurethane flexible foams, however, usually have excellent mechanics. A disadvantage of many polyurethane foams, however, is an inadequate fire behavior for many applications, which can be compensated - if at all - only by large amounts of added fire retardants.

Through the use of silicone-polyurethane copolymers, ie polysiloxanes, which also contain polyurethane and / or urea units, it is possible to develop novel foams which have new and tailored to the application exactly combinations of properties. In particular, it is thus possible to produce foams which have good mechanical properties in combination with a significantly improved fire behavior compared to conventional polyurethane foams. In WO 03/080696 silicone foams are described, which can be prepared from certain hydroxyalkyl- and / or aminoalkyl-functional polysiloxanes with di- or polyisocyanates. The crosslinking of the silicones takes place during the foaming. The blowing agent used is water which reacts with the isocyanates used in excess to release carbon dioxide and form urea units.

In WO 03/080696 two methods for foam production are described. In one method, the hydroxyalkyl- and / or aminoalkyl-functional siloxane is first emulsified with water and the resulting emulsion is then reacted with di- or polyisocyanates. In the second method, the hydroxyalkyl- and / or aminoalkyl-functional siloxane is first reacted with an excess of the di- or

Polyisocyanates reacted to form an isocyanate-functional siloxane, which is then mixed in a second reaction step with water and thereby foamed.

However, a disadvantage of both processes described in WO 03/080696 is the fact that the resulting foams often do not yet show a satisfactory property profile. For example, the foam structures obtained are often only moderate. Above all, however, the foams usually show a so-called "sweating out" of siloxane molecules which have remained uncrosslinked.

In DE 41 08 326 C1 silicone foams are described which can be prepared by a reaction of hydroxyalkyl-functional polysiloxanes with di- or polyisocyanates. To produce the siloxane foam, comparable processes are used as in WO 03/080696. Therefore, the same problems also occur here. The reaction of hydroxyalkyl- or aminoalkyl-terminated polysiloxanes with di- or polyisocyanates is also known from other references, inter alia from US 5512650 or WO 97/40103. However, this reaction is described not for the production of foams but only for the production of elastomers or prepolymers for hotmelt or Sealantanwendungen. Due to their high molecular weights and associated very high viscosities, the compounds described therein are also unsuitable for use in a process for the production of foams from prepolymers in which the crosslinking of the prepolymers should take place only during foam formation and at low temperatures.

The object of the invention was the development of siloxane-polyurethane copolymer foams, which do not have the disadvantages of the prior art.

The invention relates to a process for the preparation of organically modified organopolysiloxanes (S) which foam with foaming agents which are selected from water and physical blowing agents and cure to give foams, and which have on average at least one isocyanate function per molecule, in which Organopolysiloxanes (SI) having at least one reactive group per molecule selected from an aminoalkyl and a hydroxyalkyl group with polyisocyanates (J) having at least 2 isocyanate groups per molecule in the presence of a component which promotes solubility between the reaction partners (S1) and (J) (L ), where pro Mol reactive group at least 1.05 moles of isocyanate groups are present.

In the process according to the invention, isocyanate-functional organopolysiloxanes (S) or optionally also mixtures of these siloxanes with polyisocyanates (J) are obtained. The resulting polysiloxanes (S) are preferably linear or branched.

The organopolysiloxanes (S) or mixtures of the

Organopolysiloxanes (S) and excess polyisocyanates (J) are mostly used in foamable preparations (Z), which also contain other additives.

The organopolysiloxanes (S) according to the invention and mixtures (Z) containing them are used to produce foams, preferably rigid or flexible foams, in particular flexible foams.

The invention is based on the surprising discovery that the disadvantages of the processes described in the prior art are due to the fact that the hydroxyalkyl- and / or aminoalkyl-functional siloxanes (SI) do not react at all or only slightly with the diisocyanates or polyisocyanates (J). are miscible. This leads to the fact that in the production of silicone

Polyurethane copolymer foams according to the teaching of the prior art, a part of the siloxanes during foaming does not come into contact with the isocyanates and thus remains uncrosslinked and can "sweat".

Through the addition of the solubilizing component (L) a better mixing of the reactants (Sl) and (J) is achieved during the reaction. Preferably form the both components during the reaction a homogeneous phase. This not only leads to the silicones (Sl) reacting much more completely with the isocyanate excess, but also has the consequence that the resulting isocyanate-functional siloxanes (S) have a significantly more homogeneous molecular weight distribution. Thus, in the absence of the solubilizing component (L), the reactants (Sl) and (J) are present in the two-phase mixture, so that the reaction takes place mainly at the phase boundary. This was - if not only the isocyanates (J) but also the siloxanes (Sl) have a majority of at least two reactive groups - lead to the formation of extremely high molecular weight compounds, since at the phase boundary both the di- or polyfunctional siloxanes (Sl) and The polyfunctional isocyanates (J) to almost completely abreact.

On the other hand, if the reactants (Sl) and (J) are in a largely homogeneous phase during the reaction, a large proportion of the isocyanate functions present in excess do not react. That a large proportion of the isocyanates (J) used reacts only with one isocyanate group and thus leads to the formation of - the molecular weight limiting - chain terminations. By adding the component (L) releasing between the reaction partners (Sl) and (J), the viscosity of the resulting siloxanes (S) can thus be markedly reduced and / or gelation of the reaction mixture can be prevented.

In principle, the solubilizing component (L) may be any compound or mixture of various compounds which has been shown to improve the mutual solubility of the siloxanes (Sl) and isocyanates (J). Preferably, component (L) is inert or largely inert towards isocyanates. In a preferred embodiment of the invention, component (L) comprises compounds which remain in the finished foam, for example low-molecular flame retardants with correspondingly good solubility properties for components (S1) and (J).

However, component (L) is particularly preferably a solvent or a solvent mixture which is capable of dissolving both the siloxanes (S1) and the isocyanates (J).

The solvent (L) is preferably added in an amount which is sufficient to completely dissolve both reactants (Sl) and (J), so that their reaction takes place in a single-phase solution. Particularly preferably, the amount of the solvent (L) is chosen so that it is just just sufficient to achieve a reaction of siloxane (Sl) and isocyanate (J) in single-phase solution. Likewise, solvents having good dissolution properties are preferred, so that the smallest possible amounts of solvent are sufficient.

Examples of suitable solvents (L) are ethers, in particular aliphatic ethers, such as dimethyl ether, diethyl ether, methyl t-butyl ether, diisopropyl ether, dioxane or tetrahydrofuran, esters, in particular aliphatic esters, such as ethyl acetate or butyl acetate, ketones, in particular aliphatic ketones, such as acetone or methyl ethyl ketone, sterically hindered alcohols, in particular aliphatic alcohols, such as t-butanol, tertiary amines, such as triethylamine, tributylamine or pyridine, amides, such as DMF, aromatic hydrocarbons, such as toluene or xylene, aliphatic hydrocarbons, such as pentane, cyclopentane, hexane, cyclohexane, heptane, chlorine compounds, in particular chlorinated hydrocarbons, such as dichloromethane or chloroform and CO2 • The solvents (L) can be used individually or in mixtures. Preferred solvents (L) are ketones, ethers, chlorine compounds and esters, particular preference is given to acetone, dioxane, methyl ethyl ketone, methyl t-butyl ether, dichloromethane and tetrahydrofuran.

Preferably, the dissolution-promoting component (L) has a boiling point of 20 to 120 ⁰ C, in particular from 30 to 8O ⁰ C at 0.10 MPa.

In a preferred embodiment of the invention, a solvent or a solvent mixture is used as the solubilizing component (L), wherein the solvent or solvent mixture is completely or partially removed after the reaction of the organopolysiloxanes (Sl) and the di- and / or polyisocyanates (J. ) is completed or at least largely completed.

Particular preference is given to the following procedure: The organopolysiloxanes (S1) having at least one group per molecule selected from an aminoalkyl and a hydroxyalkyl group are reacted in the presence of a solvent (L) with an excess of polyisocyanates (J) having at least 2 isocyanate groups reacted per molecule to the isocyanate-functional siloxanes (S). In this case, the siloxanes (S1) preferably react completely, resulting in a mixture which, in addition to the isocyanate-functional siloxanes (S), also contains proportions of unreacted polyisocyanates (J). Subsequently, the solvent (L) can be completely or partially removed by distillation. The resulting foamable mixture remains preferably homogeneous, since the isocyanate-modified siloxanes (S) according to the Organomodification have a sufficient solubility for the excess isocyanates (J).

Optionally, further additives may also be added to this mixture at any time during or after its preparation in order to obtain foamable preparations (Z).

The organopolysiloxanes (S1) are preferably linear or branched. As organopolysiloxanes (SI) are preferred

Used siloxanes whose aminoalkyl or hydroxyalkyl groups of the general formula (1)

-O- (SiR ¹ R ² ) -R ³ -Z (1)

match, where

RΛ is a monovalent, optionally substituted by -CN, or halogen C] _C] _2 ~ hydrocarbon radical in which one or more, not adjacent methylene units may be replaced by groups -O- or NR ^, or optionally by C] _-C5-alkyl radicals, -CN or halogen-substituted phenyl radical, R.2 denotes a hydrogen atom or a radical RΛ,

R ^ is a divalent, optionally cyano, alkyl, hydryoxy, amino, aminoalkyl, hydroxyalkyl or halogen-substituted C] _2 hydrocarbon radical in which one or more, not adjacent to each other

Methylene units may be replaced by groups -O- or NR ^ and Z represents a group OH or NH ₂ . As radicals RA, preference is given to using unbranched alkyl groups, preferably having 1 to 6 carbon atoms, or aromatic hydrocarbons. In particular, methyl groups represent particularly preferred radicals RA. Radicals R 1 are preferably unsubstituted. Preferred radicals R 1 are in particular linear alkylene chains having 1 to 6, preferably 1 or 3, carbon atoms or cyclic hydrocarbon radicals.

Also preferred radicals R 1 are also alkylene chains having 1 to 10 carbon atoms, preferably 3 or 5 carbon atoms, whose carbon chain is interrupted by one or more oxygen atoms or a group NR ^.

Preferred radicals R 1 are hydrogen, alkyl groups, aryl groups, aminoalkyl groups or hydroxyalkyl groups, preferably each having 1 to 6 carbon atoms, hydrogen and methyl groups being particularly preferred. The group Z is particularly preferably an amine function.

Preference is given to using branched or unbranched organopolysiloxanes (S1) whose chain ends are at least 90% end-terminated, in particular at least 95%, with aminoalkyl or hydroxyalkyl groups of the general formula (1). Optionally, both aminoalkyl and hydroxyalkyl groups of the general formula (1) may be present on an organopolysiloxane molecule (S1).

Particular preference is given to using organopolysiloxanes (S1) which are either exclusively or at least 50% by weight, preferably at least 70% by weight, particularly preferably at least 90% by weight, of linear siloxanes of the general formula (2) Z -R ³ - [-SiR ¹ R ² O-] _m -SiR ¹ R ² -R ³ -Z (2)

where m is an integer, where the mean of m is between 1 and 10,000, and

RΛ, R2, R3 and Z have the above meanings.

Preferred mean values for m are from 10 to 1000, average values of from 15 to 500, in particular from 30 to 300, being particularly preferred.

In a preferred embodiment of the invention, the siloxanes (S1) of the general formula (2) are mixed with further siloxanes (S1) which on average have more than two groups which are selected from aminoalkyl and hydroxyalkyl functions. These may be both branched and with groups selected from aminoalkyl and hydroxyalkyl terminated siloxanes (SI) or also unbranched siloxanes having lateral groups selected from aminoalkyl and hydroxyalkyl functions.

In a particularly preferred process, the linear organopolysiloxanes (S1) of the general formula (2) are prepared from organopolysiloxanes of the general formula (3)

HO [-SiR ¹ ₂ O] _m -H (3),

and organosilicon compounds of the general formulas (4) to (6)

where k is an integer of at least 2 and RA and m are as defined above.

In one embodiment of the invention, siloxanes are used as component (S1) which, in addition to the amino and / or hydroxyalkyl functions, also have phosphonatoalkyl functions of the formula (7)

-R ⁵ -P (O) (OR ⁶ ) ₂ : 7)

where R ^ have the meanings of R ^ and R ° have the meanings of R ^. The phosphate functions can improve the compatibility between the siloxanes (Sl) and the isocyanates (J).

The siloxanes (S1) used in the process according to the invention preferably have the lowest possible content of siloxanes which are not reactive towards isocyanates. In particular, they preferably have the lowest possible content of non-isocyanate-reactive cyclic siloxanes. Thus, non-reactive siloxanes may optionally have a defoaming effect and thus worsen the foam structure of the cured foams. If appropriate, it may be advantageous to remove non-isocyanate-reactive siloxane cycles by distillation from the siloxanes (S1) before they are used in the process according to the invention. As polyisocyanates (J) all known di- or polyisocyanates can be used. Preference is given to polyisocyanates (J) of the general formula (8)

Q (NCO) _n (8),

used, where

Q is an n-functional aromatic or aliphatic hydrocarbon radical and n is an integer of at least 2.

Preferably, Q has 4 to 30 carbon atoms. Preferably n is an integer of at most 5. Examples of conventional diisocyanates (J) are

Diisocyanatodiphenylmethane (MDI), both in the form of crude or industrial MDI and in the form of pure 4,4 'or 2,4' isomers or their preparations, tolylene diisocyanate (TDI) in the form of its various regioisomers, diisocyanatonaphthalene (NDI), isophorone diisocyanate ( IPDI), 1, 3-bis (1-isocyanato-1-methylethyl) benzene (TMXDI) or else from

Hexamethylene diisocyanate (HDI). Examples of polyisocyanates (J) are polymeric MDI (p-MDI), triphenylmethane triisocanate or biuret or isocyanurate trimers of the abovementioned isocyanates. The di- and / or polyisocyanates (J) can be used alone or in a mixture.

In the reaction of the organosiloxanes (Sl) with the polyisocyanates (J), the polyisocyanates (J) are preferably used in an excess, so that more reactive per mole

Aminoalkyl or hydroxyalkyl group of organopolysiloxanes (Sl) at least 1.5 mol, in particular 2 to 10 moles of isocyanate groups are used. The molar excess of isocyanates is preferably consumed in the foaming for the reaction with water.

In the preparation of the organosiloxanes (S), in addition to the siloxanes (Sl) and the polyisocyanates (J) also other

Components with isocyanate functions and / or isocyanate-reactive groups are used and incorporated into the organosiloxanes (S). Examples include its monoisoyananates, isocyanate-functional organic oligomers or (pre-) polymers, monomeric alcohols, monomeric diols such as glycol, propanediol, butanediol, monomeric oligools such as pentaerythritol or trihydroxymethylethane, oligomeric or polymeric alcohols having one, two or more hydroxyl groups such as polyethylene or Polypropylene oxides, water, monomeric amines having one, two or more amine functions such as ethylenediamine, hexamethylenediamine and also oligomeric or polymeric amines having one, two or more amine functions. The proportion by weight of these additional compounds is typically below 30% by weight, preferably below 15% by weight and particularly preferably below 5% by weight, based on the isocyanate-functional organosiloxanes (S1).

The preparation according to the invention of the siloxanes (S) can be accelerated by the use of catalysts (K). As catalysts (K) it is preferred to use acidic or basic compounds, e.g. partially esterified phosphoric acids, carboxylic acids, partially esterified carboxylic acids,

Alkylammonium hydroxides, ammonium alkoxides, alkylammonium fluorides or amine bases, organotin compounds, organo-zinc compounds, organotitanium compounds. If appropriate, the catalysts (K) used are deactivated after the end of the reaction, for example by addition of catalyst poisons or - in the case of acidic or basic catalysts (K) - by neutralization. This deactivation allows the Storage stability of the siloxanes (S) or of the preparations (Z) containing them can be improved.

The organopolysiloxanes (S) or mixtures of the organopolysiloxanes (S) and excess polyisocyanates (J) according to the invention are generally used in foamable preparations (Z), which also contain further additives. The addition of all additives can take place at any time before, during or after the preparation according to the invention of the organosiloxanes (S).

A preferred addition to the foamable preparations (Z) are fillers (F). Here, all non-reinforcing fillers, ie fillers having a BET surface area of up to 50 m 2 / g, such as chalk or reinforcing fillers, ie fillers with a BET surface of at least 50 m ^ / g, such as carbon black, precipitated silica or fumed silica are used. In particular, hydrophobic as well as hydrophilic fumed silicas represent a preferred filler. In a particularly preferred

Embodiment of the invention, a fumed silica is used whose surface has been modified with hydroxyalkyl or in particular with aminoalkyl functions. This modified silica can be chemically incorporated into the foam polymer. The fillers (F) - especially fumed silicas used as fillers - can perform various functions. Thus, they can be used to adjust the viscosity of the foamable mixture (Z). Above all, however, they can perform a "supporting function" during foaming and thus lead to foams with better foam structure, since the mechanical properties of the resulting foams can also be explained by the Use of fillers (F) - especially by the use of fumed silica - significantly improved.

Furthermore, the foamable preparations (Z) may contain catalysts (K2) which accelerate foam curing. As catalysts (K2) are u.a. Organotin compounds suitable. Examples are dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate or dibutyltin bis (dodecylmercaptide). In addition, tin-free catalysts (K2), e.g. organic titanates, iron catalysts, such as organic iron compounds, organic and inorganic heavy metal compounds or amines in question. An example of an organic iron compound is iron (III) acetylacetonate. Examples of amines are triethylamine, tributylamine, 1,4-diazabicyclo [2,2,2] octane, N, N-bis (N, N-dimethyl-2-aminoethyl) -methylamine, N, N-dimethylcyclohexylamine, N, N-dimethylphenyamine, bis-N, N-dimethylaminoethyl ether, N, N-dimethyl-2-aminoethanol, N, N-dimethylaminopyridine, N, N, N, N-tetramethylbis (2-aminoethylmethylamine, 1 , 5-Diazabicyclo [4.3.0] non-5-ene, 1,8-diazabicyclo [5.4.0] undec-7-ene, N-ethylmorpholine or N, N'-dimethylaminopyridine.

The catalysts (K2) can be used individually or as a mixture. If appropriate, the catalysts (K) used in the preparation of the siloxanes (S) can simultaneously also serve as catalysts (K2) for foam curing.

Based on the foamable preparation (Z), the catalyst (K2) is preferably used in an amount of 0.1-6.0 wt .-%, particularly preferably in an amount of 0.3 to 4.0 wt .-%. In many cases it is advantageous to add foamable stabilizers (ST) to the foamable preparations (Z). Examples of suitable foam stabilizers (ST) which may be used are the commercially available silicone oligomers modified by polyether side chains, which are also used to prepare conventional polyurethane foams. The foam stabilizers are used in amounts of up to 6% by weight, preferably from 0.3 to 3% by weight, in each case based on the foamable preparations (Z).

Furthermore, the addition of cell regulators, thixotropic agents and / or plasticizers may also be advantageous. To further improve the fire resistance, flame retardants may also be added to the foamable preparations (Z), e.g. Phosphorus-containing compounds, especially phosphates and phosphonates, as well as halogenated polyesters and polyols or chlorinated paraffins.

In addition, the preparations (Z) may also contain physical blowing agents (T). The physical blowing agents (T) used are preferably low molecular weight hydrocarbons such as propane, butane or cyclopentane, dimethyl ether, fluorinated hydrocarbons such as 1, 1-difluoroethane or 1,1,1,2-tetrafluoroethane or CO2. The foam production can optionally be carried out exclusively by the physical blowing agent (T). In most cases, however, foaming takes place primarily by reaction of the isocyanate-functional siloxanes with water as the chemical blowing agent. However, in this case as well, the use of physical blowing agents (T) in combination with water as a chemical blowing agent can be advantageous in order to obtain lesser density foams. The siloxanes (S) or the formulations (Z) containing them are preferably used for the preparation of siloxane-polyurethane copolymer foams or siloxane-polyurea copolymer foams. The siloxanes (S) or preparations (Z) can be used in the form of 1-component systems. The foam is formed by a physical blowing agent (T). After application of the foam, it hardens by reacting with the humidity.

However, the siloxanes (S) or the preparations (Z) are preferably used in 2-component systems in which both components are mixed together shortly before foaming. The curing of the foam is then carried out by a reaction of the two components with each other. The siloxanes (S) and the preparations (Z) are the first

Foam component. In principle, both water and all compounds (V) having preferably at least two isocyanate-reactive functions serve as the second component. Examples of suitable compounds (V) are aminoalkyl- or hydroxyalkyl-functional siloxanes (S1) as well as monomeric alcohols, monomeric diols such as glycol, propanediol, butanediol, monomeric oligools such as pentaerythritol or trihydroxymethyl, oligomeric or polymeric alcohols having one, two or more hydroxyl groups such as Etylene or propylene glycols, water, monomeric amines having one, two or more amine functions such as ethylenediamine, hexamethylenediamine and also oligomeric or polymeric amines having one, two or more amine functions called. The foaming takes place with a physical blowing agent (T), the foam curing by the reaction of the siloxanes (S) with the second foam component.

However, the second foam component as the isocyanate-reactive compound preferably contains, above all, water. Foaming as well as foam hardening takes place by a reaction of the siloxanes (S) with the water. However, foam formation can also be assisted by the use of a physical blowing agent (T) and foam curing by the use of further isocyanate-reactive compounds (V) having preferably at least two isocyanate-reactive functions. In a preferred embodiment of the invention, the second component contains no further isocyanate-reactive compounds other than water.

If the siloxanes (S) or preparations (Z) are used in the form of 2-component mixtures, all additives such as the catalysts (K2), fillers (F), foam stabilizers (ST), physical blowing agents (T), cell regulators, Thixotropic agents and / or fire retardants of each of the two components or optionally even present in both components simultaneously. In a preferred embodiment of the invention, in particular the catalysts (K2) are not added to the siloxanes (S) or formulations (Z) but to the second isocyanate-reactive component so as to improve the storage stability of the siloxanes (S) or of the preparations containing them ( Z) increase.

If the siloxanes (S) or formulations (Z) are used in the form of 2-component mixtures, it may also be advantageous to use one or more further solubilizing components (L2) in order to improve the compatibility of the two foam components with one another. This is especially true when the second foam component contains water as an isocyanate-reactive compound. This further solubilizing component (L2) may be, on the one hand, an emulsifier (E) which facilitates or facilitates the formation of silicone-water emulsions. To be favoured while 0.001-0.5 g, more preferably 0.02-0.1 g of emulsifier per 1 g of water used. Examples of emulsifiers (E) are, for example, fatty alcohol polyglycol ethers,

Fatty alcohol polyglycerol ether, polyoxyethylene glycerol ester isotridecanol ethoxylate or polyol-modified silicone oils.

In a particularly preferred embodiment of the invention, however, solvent or solvent mixtures are used as solubilizing components (L2). Also particularly advantageous is the combined use of solvents and emulsifiers (E). In principle, the same solvents or solvent mixtures which are also used as component (L) can be used. The solvent or solvent mixture is preferably used in the second, water-containing foam component, with water-soluble solvents being particularly preferred. Examples of particularly suitable solvents are THF, dioxane, chloroform or acetone.

All the above symbols of the above formulas each have their meanings independently of each other. In all formulas, the silicon atom is tetravalent.

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 :

49.10 g of a linear organopolysiloxane of the formula H ₂ N- (CH ₂ ) 3 - [(CH ₃ ) ₂ -SiO] _{1 2} 9Si (CH ₃ ) ₂ - (CH ₂ ) 3 -NH ₂ were prepared in 50 ml of absolute THF at 0 ⁰ C with p-MDI (0.10 g in 30 ml of absolute THF) within 50 min. The resulting solution was then at 0 ⁰ C within 30 min to a solution of TDI (4.30 g in 18 ml of absolute THF) was added dropwise and brought to 0 ⁰ C for reaction. The reaction mixture was then warmed to room temperature, stirred for a further two hours and then freed of the solvent in vacuo.

Example 2:

10.00 g of the prepolymer of Example 1 were dissolved in 3.2 ml of absolute THF and admixed with 0.08 g of N, N, N ', N'-tetramethyl-bis (2-aminoethyl) methylamine (Jeffcat® PMDETA from Hutsman Corp.). as catalyst and 0.11 g emulsifier (Atlas® G-1300 from Deutsche ICI GmbH, Frankfurt am Main). The resulting mixture was first processed with a high-speed KPG stirrer to a homogeneous emulsion. Subsequently, 0.18 g of water was added quickly and again emulsified by a high-speed KPG stirrer to a homogeneous mixture. After about 30 sec. Began an exothermic reaction with foaming. The foaming was completed after a further approx. 30 sec., While the heat development continued for approx. 60 sec. The result was an elastic, coarse-pored foam, which proved to be non-combustible in the Bunsen burner flame.

Example 3:

The procedure of Example 2 was repeated with the difference that the amount of water halved to 0.09 g again. This resulted in an elastic, incombustible foam with a coarse foam structure.

Example 4 The procedure of Example 2 was repeated with the difference that the addition of water took place in the form of an ethereal solution (0.18 g of water in 3.0 ml of THF). It resulted in an elastic, incombustible foam with fine fine pore size.

Example 5 The procedure of Example 4 was repeated with the difference that the amount of catalyst N, N, N ', N'-tetramethyl-bis (2-aminoethyl) methylamine doubled to 0.16 g. This resulted in an elastic, incombustible foam with fine fine pore size. Compared with the foam of Example 4, the average pore size was slightly lowered.

Example 6:

The procedure according to the procedure of Example 2 was followed with the difference that 0.05 g of a hydrophilic, pyrogenic

Silica (HDK® V15 from Wacker) was homogeneously dispersed in the prepolymer prior to the addition of water. This resulted in an elastic, incombustible foam with a fine pore size. While the pore size was comparable to the foam of Example 5, this foam had a significantly higher mechanical hardness.

Example 7:

The procedure of Example 2 was repeated with the difference that 0.20 g of a hydrophilic, fumed silica (HDK® V15 from Wacker) was homogeneously dispersed in the prepolymer prior to the addition of water. This resulted in an elastic, incombustible medium pore foam. Compared with the foam of Example 6, this foam had a high density and an extremely high mechanical hardness.

Claims

Claims:

1. A process for preparing organically modified organopolysiloxanes (S) which react with blowing agents selected from water and physical

Propellants, foam and cure to foam, and having an average of at least one isocyanate function per molecule, wherein the organopolysiloxanes (SI) having at least one reactive group per molecule, which is selected from an aminoalkyl and a hydroxyalkyl group with polyisocyanates (J) at least 2 isocyanate groups per molecule in the presence of a between the reactants (Sl) and (J) solution-mediating component (L) are reacted, wherein per mole of reactive group at least 1.05 moles of isocyanate groups are present.

2. The method of claim 1, wherein component (L) is a solvent or solvent mixture capable of dissolving both the siloxanes (S1) and the isocyanates (J).

3. The method according to claim 1 or 2, wherein the solvent (L) is added in an amount sufficient to completely dissolve both reactants (Sl) and (J).

4. The method of claim 1 to 3, wherein the solvent

(L) is selected from ethers, esters, ketones, tertiary amines, aromatic and aliphatic hydrocarbons, chlorinated hydrocarbons and CO2 •

5. The method of claim 1 to 4, wherein the organopolysiloxanes

(S1) are used, their aminoalkyl or hydroxyalkyl groups of the general formula (1)

-O- (SiR ¹ R ² ) -R ³ -Z (1)

match, where

RΛ is a monovalent, optionally substituted by -CN, or halogen C] _C] _2 ~ hydrocarbon radical in which one or more, not adjacent methylene units may be replaced by groups -O- or NR ^, or optionally by C] C 1 -C 5 -alkyl radicals, -CN or halogen-substituted phenyl radical, R 2 denotes a hydrogen atom or a radical RΛ, R 1 denotes a divalent, optionally cyano-, alkyl-, hydryoxy-, amino-, aminoalkyl-, hydroxyalkyl- or halogen-substituted C! _-C] _2 ~ hydrocarbon radical in which one or more, not adjacent to each other

Methylene units can be replaced by groups -O- or NR ^ and

Z represents a group OH or NH2.

6. Isocyanate-functional organopolysiloxanes (S) obtainable by the process of claims 1 to 5.

7. Foamable preparations (Z) containing organopolysiloxanes (S) according to claim 6 and further additives.

8. Foamable preparations (Z) according to claim 8, which contain mixtures of the organopolysiloxanes (S) and polyisocyanates (J).

9. foams producible by use of the organopolysiloxanes (S) according to claims 1 to 6 and from the foamable preparations (Z) according to claims 7 and 8.