EP2649110A1

EP2649110A1 - Silicone-containing polyurethane foam

Info

Publication number: EP2649110A1
Application number: EP11794093.2A
Authority: EP
Inventors: Jens Cremer; Steffen Jungermann
Original assignee: Wacker Chemie AG
Current assignee: Wacker Chemie AG
Priority date: 2010-12-06
Filing date: 2011-12-05
Publication date: 2013-10-16
Also published as: DE102010062482A1; KR20130080863A; JP2013545849A; WO2012076439A8; CN103282397A; US8785511B2; US20130253085A1; WO2012076439A1

Abstract

The invention relates to foamable preparations containing (A) siloxanes of formula (I), wherein the radicals and indices which have the meaning as cited in claim 1, under the proviso that at least one radical R³ in formula (I) has the meaning of optionally substituted hydrocarbon radical and has at least one hydroxyl group and/or thiol group, and (B) polyisocyanates, silicon-containing polyurethane foams, in particular shaping foams, with low density. The invention also relates to methods for the production thereof.

Description

Silicone-containing polyurethane foam

The invention relates to foamable preparations based on organosilicon compounds, silicone-containing polyurethane foams, in particular molded foams, having low densities and processes for their preparation.

Polyurethane foams are generally made by reacting a polyisocyanate with compounds containing two or more active hydrogen atoms. The active hydrogen-containing compounds are usually polyols, primary and secondary polyamines, and water. Between these reactants, two main reactions take place during the production of a polyurethane foam. These reactions must, in principle, proceed simultaneously and at a competitively balanced rate during the process to obtain a polyurethane foam having desired physical properties. The reaction between the isocyanate and the polyol or polyamine, commonly referred to as a gel reaction, results in the formation of a high molecular weight polymer. The progress of this reaction increases the viscosity of the mixture and generally contributes to cross-linking formation with polyfunctional polyols. The second main reaction takes place between the polyisocyanate and water. This reaction contributes to urethane polymer growth and is important for the formation of carbon dioxide gas which promotes foaming. As a result, this reaction is often referred to as the blowing reaction. Both the gel and the blowing reactions take place in foams that are partially or completely driven by carbon dioxide gas. For example, if the carbon dioxide evolution is too fast compared to the gel reaction, the foam tends to collapse. Alternatively, if the gel expansion reaction is too fast compared to the carbon dioxide-generating blowing reaction the foam increase is limited, resulting in a high density foam. Also, poorly aligned cross-linking reactions will adversely affect foam stability.

The polyols used are generally polypropylene glycols, which can be prepared according to the prior art in a variety of topologies and differ from each other in molecular weight, the degree of branching and the OH number. Despite the wide structural variation of these polyols and the associated customization of the polyurethane foams for virtually any application, the commercially available polyurethane foams have their inherent flammability as a serious drawback. Despite great efforts, it has not yet been possible to establish absolutely incombustible PU foams on the market, even though intensive research activities have not been lacking in recent decades

To improve the flame retardancy properties of polymer foams.

A path to fire-retardant PU flexible foams is taken with silicone flexible silicone foams. In this case, the readily combustible polyol component used in standard PU foams is replaced by non-combustible OH-terminated siloxanes. Through the use of silicone-polyurethane copolymers, i. Of polysiloxanes which also contain polyurethane and / or urea units, it is possible to use such incombustible

To develop foams that have new combinations of properties tailored to the specific application. Reference is made, for example, to EP 1485419 Bl, which describes the preparation of silicone-polyurethane foams starting from alkylamino- or alkylhydroxy-terminated silicone oils and diisocyanates in the so-called "one-shot process." DE describes further

102006013416 AI from the production of silicone PU foams Prepolymers which are prepared on the basis of alkylamino or alkylhydroxy-terminated silicone oils and diisocyanates in a solvent-based process. The silicone polyurethane foams described so far have in common that they are based on linear or only very

weak but statistically branched siloxanes are produced in the side chains. Due to this linear siloxane chain, no rapid molecular weight build-up takes place during the expansion phase, so that only a relatively slow increase in viscosity takes place during the rise phase, as a result of which the polymer matrix is generally readily flowable even after the blowing reaction has ended and therefore the fine cell structure is complete curing of the foam can still collapse. Even if only a small part of the cell structure collapses, this leads to an irregular and coarse cell distribution. In order to counteract cell collapse when using linear polyol components, the struts between the individual foam cells must not fall below a critical diameter during the rising phase. This ensures that the still flowable polymer matrix can counteract the impending collapse of the foam structure. However, if the desired foam density is chosen too low, the cell struts become thinner and thinner during the ascent phase until they finally become too flexible to stabilize the cell structure. Accordingly, with linear siloxanes, generally only silicone PU foams having densities well above 100 kg / m ³ are obtained. Furthermore, in the case of the previously described silicone PU

Foaming adversely, that NCO-terminated silicone prepolymers must be used when silicone PU foams are to be obtained with low densities. The production of appropriate On the one hand, prepolymers are associated with an additional synthesis step, and on the other hand, such prepolymers have only a limited storage stability, especially at elevated temperatures. It would therefore be desirable to have a process which could make use of the classic "one-shot method" in the production of foam, in which the polyol and isocyanate components would be produced independently of each other and reacted with each other during the foaming process With the known NCO-terminated silicone prepolymers, no molded foams with optimum properties are produced since they have very coarse and irregular foam cells directly under the outer skin, giving the haptic impression of a low-quality molded foam Accordingly, it is desirable to use silicone PU foams with the same To do this, they must have a completely closed and homogeneous foam surface, which passes directly into the fine-cell foam structure of the foam interior.

The invention relates to foamable compositions containing

(A) siloxanes of the formula

wherein R may be the same or different and is hydrogen or a monovalent, optionally substituted hydrocarbon radical,

R ^{1 may be the} same or different and is a divalent, optionally substituted hydrocarbon radical which may be interrupted by heteroatoms,

R ^{2 may be the} same or different and is a divalent, optionally substituted hydrocarbon radical which may be interrupted by heteroatoms,

R ^{3 may be} identical or different and is hydrogen or monovalent, optionally substituted hydrocarbon radical,

X may be the same or different and represents -O-, -S- or -NR ⁴ -,

R ⁴ is hydrogen or monovalent, optionally substituted hydrocarbon radical,

n may be identical or different and an integer greater than or equal to 1, preferably 1 to 1000, particularly preferably 5 to 500, in particular 5 to 50, and

m is an integer greater than or equal to 1, preferably 1 to 20, particularly preferably 1 to 10, in particular 1 to 5, with the proviso that at least one radical R ³ in formula (I) has the meaning of optionally substituted hydrocarbon radical and at least one hydroxyl group and / or thiol group,

and

(B) polyisocyanates.

Although not shown in formula (I), up to 1%, preferably up to 0.1% of all siloxane units can have branching by way of preparation, such as in RSi0 _3/2 or Si0 _4/2 units. Examples of R are alkyl radicals, such as the methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert. Butyl, n-pentyl, iso-pentyl, neo-pentyl, tert. -Pentyl, hexyl, such as the n-hexyl, heptyl, such as the n-heptyl, octyl, such as the n-octyl and iso-octyl, such as

2, 2, 4-trimethylpentyl radical, nonyl radicals, such as the n-nonyl radical, decyl radicals, such as the n-decyl radical, dodecyl radicals, such as the n-dodecyl radical; Alkenyl radicals, such as the vinyl and allyl radicals; Cycloalkyl radicals, such as cyclopentyl, cyclohexyl, cycloheptyl radicals and methylcyclohexyl radicals; Aryl radicals, such as the phenyl and the naphthyl radical; Alkaryl radicals, such as o-, m-, p-tolyl radicals, xylyl radicals and ethylphenyl radicals; Aralkyl radicals, such as the benzyl radical, the a- and the ß-phenylethyl radical. Examples of substituted hydrocarbon radicals R are alkoxyalkyl radicals, such as methoxymethyl and ethoxymethyl radicals, hydroxyalkyl radicals, such as 2-hydroxyethyl radicals, and aminoalkyl radicals, such as dimethylaminoethyl, diethylaminomethyl, 2-aminoethyl and N-methylaminoyethyl radicals.

Radical R is preferably monovalent, optionally substituted hydrocarbon radicals having 1 to 40 carbon atoms, more preferably hydrocarbon radicals having 1 to 6 carbon atoms, in particular the methyl radical.

Examples of radical R ¹ are methylene, ethylene, propylene, butylene, pentylene, hexamethylene, Methyloxyethylen-, ie the radical -CH ₂ -O-CH ₂ CH ₂ -, toluene, methylene-bis-phenylene , Phenylene, naphthylene, cyclohexylene and isophorone radicals.

R ¹ is preferably a divalent aliphatic hydrocarbon radical which may be interrupted by heteroatoms, more preferably propylene, methylene and methyl radicals. oxyethylene radicals, in particular methylene and Methyloxyethyl- enreste, most preferably the methylene radical.

Examples of radical R ² are methylene, ethylene, propylene, butylene, pentylene, hexamethylene, methyloxyethylene, ie the radical -CH ₂ -O-CH ₂ CH ₂ -, toluene, methylene-bis-phenylene , Methylene-bis-cyclohexylene, phenylene, naphthylene, cyclohexylene, 1,3-bis (1-methylethylene) benzene and isophorone radicals. R ² is preferably a divalent, aromatic or aliphatic hydrocarbon radical, particularly preferably toluolylene, methylene-bis-phenylene, methylene-bis-cyclohexylene, phenylene, naphthylene, cyclohexylene, 1, 3 Bis (1-methylethylene) benzene and isophorone radicals, in particular toluene-, phenylene-, 1,3-bis (1-methylethylene) benzene and isophorone radicals, very particularly preferably the toluolylene radical.

Examples of R ³ are the examples given for radical R and optionally substituted hydrocarbon radicals having at least one hydroxyl group and / or thiol group, for example hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, 1-hydroxypropyl, 2-hydroxypropyl , 1-hydroxybutyl, thiolmethyl, 1-thiolethyl and 1-thiolpropyl radicals. R ³ is preferably optionally substituted hydrocarbon radicals having at least one hydroxyl group and / or thiol group, particularly preferably optionally substituted hydrocarbon radicals having at least one hydroxyl group, in particular hydroxyalkyl radicals having 1 to 6 carbon atoms.

In the case of the siloxanes (A) of the formula (I) used according to the invention, both radicals R ³ preferably carry hydroxyl groups. Preferably, X is -O-

Examples of R ⁴ are the examples given for radical R.

Radical R ⁴ is preferably hydrogen.

The siloxanes (A) of the formula (I) used according to the invention have a viscosity of preferably 100 to 10,000 mPas, more preferably 500 to 5000 mPas, in each case at 25 ° C. and measured in accordance with AS M D 4283.

Examples of siloxanes (A) used according to the invention are

and

The siloxanes (A) used according to the invention are preferably:

With particular preference the siloxanes (A) used according to the invention are:

and

A further subject of the invention siloxanes of the formula (I) in which the radicals and indices have one of the abovementioned meanings,

with the proviso that at least one radical R ³ in formula (I) has the meaning of optionally substituted hydrocarbon radical and has at least one hydroxyl group and / or thiol group.

The siloxanes (Ά) used according to the invention can be prepared by methods customary in silicon chemistry.

The siloxanes (A) used according to the invention are preferably prepared by reacting

(i) linear, with amino, hydroxy or thiol-a, ω-functionalized siloxanes with

(ii) diisocyanates and

(iii) amines

produced . Component (i) is preferably siloxanes of the formula

wherein R, X and n each have one of the meanings given above.

Although not shown in formula (II), production-related up to 1%, preferably up to 0.1%, of all units may have branching, such as in RSiO _3/2 or SiO _4/2 units.

Examples of component (i) are

HIGH ₂ - [SiMe ₂ O] _2-100 -SiMe ₂ CH ₂ OH,

HOCH ₂ -CH ₂ -OCH ₂ - [SiMe ₂ 0] ₂ _ ₁₀₀ -SiMe ₂ CH ₂ O-CH ₂ -CH ₂ OH,

H ₂ NCH ₂ - [SiMe ₂ O] ₂ _ ₁₀₀ -SiMe ₂ CH ₂ NH ₂ ,

H ₂ NCH ₂ -CH ₂ -CH ₂ - [SiMe ₂ O] ₂ _ ₁₀₀ -SiMe ₂ CH ₂ -CH ₂ -CH ₂ NH ₂ and

H ₃ C-HNCH ₂ -CH ₂ -CH ₂ - [SiMe ₂ O] ₂ _ ₁₀₀ -SiMe ₂ CH ₂ -CH ₂ -CH ₂ NH-CH 3

where Me is methyl.

Component (i) is preferably

HIGH ₂ - [SiMe ₂ O] ₂ - ₁₀₀ -SiMe ₂ CH ₂ OH and

HIGH ₂ -CH ₂ -OCH ₂ - [SiMe ₂ O] ₂ _ ₁₀₀ -SiMe ₂ CH ₂ O-CH ₂ -CH ₂ OH,

HOCH ₂ - [SiMe ₂ O] _2-100 -SiMe ₂ CH ₂ OH being particularly preferred.

The siloxanes (i) are commercially available products or can be prepared by methods customary in silicon chemistry.

The disocyanates (ii) used according to the invention are all known diisocyanates. Examples of diisocyanates (ii) 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, diisocyanato naphthalene (NDI), isophorone diisocyanate (IPDI), 1,3-bis (1-isocyanato-1-methylethyl) benzene (TMXDI), 4,4'-diisocyanatodicyclohexylmethane (H ₁₂ MDI) and hexamethylene diisocyanate (HDI In the process according to the invention, diisocyanates (ii) are used in amounts of preferably 0.1 to 30 parts by weight, more preferably 0.1 to 20 parts by weight, in particular 1 to 10 parts by weight, in each case based on 100 parts by weight of siloxane (i).

The amines (iii) used according to the invention are preferably those of the formula

HNR ³ ₂ (III), wherein R ^{3 have} one of the meanings mentioned above.

Examples of amines (iii) are ethanolamine, N-methylethanolamine, diethanolamine, N-methylpropanolamine, bis (2-hydroxypropyl) amines, N-methyl (thioethanol) amine.

The amines (iii) are preferably aliphatic amines, more preferably diethanolamine, N-methylethanolamine, bis (2-hydroxypropyl) amines and N-methyl (thioethanol) amine, in particular diethanolamine and bis (2-hydroxypropyl ) amine.

According to the invention, amines (iii) are used in amounts of preferably 0.1 to 20 parts by weight, more preferably 0.1 to 10 parts by weight. parts, in particular 0.5 to 5 parts by weight, in each case based on 100 parts by weight of siloxane (i) used.

In the reaction of the educts (i), (ii) and (iii), organic solvents (iv) and catalysts (v) can be used.

Examples of organic solvents (iv) 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, especially aliphatic ketones, such as acetone or methyl ethyl ketone, sterically hindered alcohols, especially aliphatic alcohols such as t-butanol, amides such as DMF, aliphatic nitriles such as acetonitrile, aromatic hydrocarbons such as toluene or xylene, aliphatic hydrocarbons such as pentane, cyclopentane, hexane, cyclohexane, heptane, chlorinated hydrocarbons such as methylene chloride or chloroform. If organic solvents (iv) are used, they are amounts of preferably 1 to 1000 parts by weight, more preferably 10 to 500 parts by weight, in particular 30 to 200 parts by weight, based in each case on 100 parts by weight of siloxane (i). In the reaction according to the invention, preference is given to using no solvents (iv).

Examples of catalysts (v) are tin compounds, such as dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, dibutyltin bis (dodecylmercaptide), tin (II) - (2-ethylhexanoate) and zinc compounds, such as zinc (II) - ( 2-ethylhexanoate) and bismuth compounds such as bismuth (III) neodecanoate and zirconium compounds such as zirconium tetrakis (2, 2, 6, 6 tetramethylheptane-3,5-dionates) and amines such as 1-diazabicyclo [2,2,2] octane and tetramethylguanidine.

Preferably, the catalysts (v) are tin, zirconium or bismuth compounds, with bismuth compounds being particularly preferred.

If catalysts (v) are used, these are amounts of preferably 1 to 1000 ppm by weight, more preferably 10 to 500 ppm by weight, in particular 50 to 150 ppm by weight, in each case based on the total weight of the reaction mixture. In the reaction according to the invention, preference is given to using catalysts (v). The components used for the reaction according to the invention may in each case be one type of such a component as well as a mixture of at least two types of a respective component. In the process according to the invention, siloxanes (i) are preferably reacted in a first stage with diisocyanates (ii) optionally in the presence of solvent (iv) and optionally in the presence of catalyst (v), and the reaction mixture obtained in a second stage with amines ( iii) implemented.

The reaction according to the invention is carried out at temperatures of preferably 10 to 100.degree. C., particularly preferably 20 to 80.degree.

The reaction according to the invention is preferably carried out at the pressure of the surrounding atmosphere, ie 900 to 1100 hPa. she but can also at higher pressures, such as at 1200 to

10 000 hPa.

The reaction according to the invention is preferably carried out under an inert gas atmosphere, e.g. Nitrogen and argon, performed.

The reaction mixture obtained after completion of the reaction can be worked up by any and previously known methods. If a solvent is used in the reaction, it is preferably removed during the work-up, which is particularly preferably carried out by distillation and, within the scope of the technical possibilities, completely. The reaction mixture preferably contains no starting materials. If the reaction mixture still contains unreacted educts, these remain preferentially there.

As isocyanates (B) used according to the invention, it is possible to use all known diisocyanates or polyisocyanates, for example the diisocyanates listed above under (ii), and polymeric MDI (p-MDI), triphenylmethane triisocyanate or biuret or isocyanurate trimers of the abovementioned isocyanates.

Preferred polyisocyanates (B) are those of the general formula used, where

Q is a b-functional, optionally substituted hydrocarbon radical and

b is an integer of at least 2, preferably from 2 to 10, particularly preferably 2 or 4, in particular 2 to 3, means. Preferably, Q is optionally substituted hydrocarbon radicals having 4 to 30 carbon atoms, more preferably hydrocarbon radicals having 6 to 25 carbon atoms.

The preparations according to the invention contain polyisocyanates (B) in amounts of preferably 0.1 to 150 parts by weight, more preferably 1 to 100 parts by weight, in particular 10 to 50 parts by weight, based in each case on 100 parts by weight of siloxane (A).

In addition to the siloxanes (A), polyisocyanates (B), the preparations of the invention may contain other substances, e.g. Fillers (C), emulsifiers (D), physical blowing agents (E), catalysts (F), chemical blowing agents (G) and additives (H).

If fillers (C) are used, they can be any non-reinforcing fillers, ie fillers with a BET surface area of up to 50 m ² / g, such as chalk, or reinforcing fillers, ie fillers with a BET surface area of at least 50 m ² / g, such as carbon black, precipitated silica or fumed silica. In particular, hydrophobic and hydrophilic fumed silicic acids are a preferred filler. In a particularly preferred embodiment of the invention, a hydrophobic fumed silica whose surface has been modified with trimethylsilyl groups is used. The optionally used fillers (C) - in particular pyrogenic silicas - can perform various functions. So they can be used to adjust the viscosity of the foamable mixture. Above all, however, they can perform a "supporting function" during foaming and thus lead to foams having a better foam structure. Finally, the mechanical properties of the resulting foams can be decisively improved by the use of fillers (C), in particular by the use of fumed silica. Further, as fillers (C), there may be added exfoliation graphite, inorganic silicates such as wollastonite, talc or glass powder, and inorganic phosphates such as calcium hydrogenphosphate or ammonium polyphosphate. If the preparations according to the invention contain fillers (C), these are amounts of preferably 0.1 to 30 parts by weight, more preferably 0.1 to 20 parts by weight, in particular 0.1 to 15 parts by weight, based in each case on 100 parts by weight of siloxane (A) , The preparations according to the invention preferably contain fillers (C).

In many cases it is advantageous to add emulsifiers (D) to the foamable preparations. Examples of suitable emulsifiers (D) which also serve as foam stabilizers are all commercially available silicone oligomers modified by polyether side chains, which are also used to prepare conventional polyurethane foams. If emulsifiers (D) are used, these are amounts of preferably up to 6% by weight, particularly preferably from 0.3 to 3% by weight, in each case based on the total weight of the foamable preparations. The preparations according to the invention preferably contain no emulsifiers (D).

In addition, the preparations according to the invention may also contain compounds (E) which may serve as physical blowing agents. As component (E) 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 used. The Schaurabildung preferably takes place by a reaction of the polyisocyanates (B) with the component (G) as a chemical blowing agent. The use of physical blowing agents (E) in combination with component (G) as a chemical blowing agent may be advantageous in order to obtain lesser density foams. If the preparations according to the invention comprise constituent (E), these are amounts of preferably 0.1 to 30 parts by weight, more preferably 0.1 to 20 parts by weight, in particular 0.1 to 15 parts by weight, based in each case on 100 parts by weight of siloxane (A) , The preparations according to the invention preferably contain no physical blowing agent (E).

Furthermore, the foamable preparations according to the invention may contain catalysts (F) which accelerate foam curing. Suitable catalysts (F) include organotin compounds. Examples are dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, dibutyltin bis (dodecylmercaptide) or tin (II) - (2-ethylhexanoate). In addition, tin-free catalysts (F) such as heavy metal compounds or amines come into question. Examples of tin-free catalysts include iron (III) acetylacetonate, zinc (II) octoate, zirconium (IV) acetylacetonate, bismuth (III) neodecanoate. 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, -dimethylphenylamine, bis-N, -dimethylaminoethyl ether, N, N-dimethyl-2-aminoethanol, N, N-dimethylaminopyridine, N, N, N, N-tetramethyl-bis (2-aminoethylmethylamine, 1, 5 Diazabicyclo [4.3.0] ηοη-5-ene, 1,8-diazabicyclo [5. .0] undec-7-ene, N-ethylmorpholine, tetramethylguanidine or Ν, Ν '-dirnethylaminopyridine.

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

If catalyst (F) is used, the amounts are preferably from 0.1 to 6.0% by weight, more preferably from 0.1 to 3.0% by weight, in each case based on the total weight of the inventive foamable preparation. The preparations according to the invention preferably contain catalysts (F). In principle, both water and all compounds having preferably at least one isocyanate-reactive function can serve as chemical blowing agents (G).

Examples of component (G) are aminoalkyl- or hydroxy-functional siloxanes which are different from component (A), monomeric alcohols, monomeric diols, such as glycol, propanediol and butanediol, monomeric oligools, such as pentaerythritol or

Trihydroxymethylethane, oligomeric or polymeric alcohols having one, two or more hydroxyl groups, such as ethylene or propylene glycols, water, monomeric amines having one, two or more amine functions, such as ethylenediamine and hexamethylenediamine, and also oligomeric or polymeric amines having one, two or more several amine functions. If component (G) is used, these are preferably hydroxy compounds, with water being particularly preferred. If component (G) is used, these are amounts of preferably 0.1 to 20 parts by weight, more preferably from 0.1 to 15 parts by weight, in particular from 0.1 to 10 parts by weight, based in each case on 100 parts by weight of siloxane. (A). Preferably, the compositions according to the invention contain component (G).

Examples of optional additives (H) are cell regulators, plasticizers, e.g. Silicone oils which are different from component (A), flame retardants, e.g. Melamine or phosphorus-containing compounds, especially phosphates and phosphonates, as well as halogenated polyesters and polyols or chlorinated paraffins. Examples of silicone oils (H) are triorganosiloxy-terminated polydiorganosiloxanes, such as trimethylsiloxy-terminated polydimethylsiloxanes, and the siloxanes mentioned above under i).

The additives (H) are preferably cell regulants and flame retardants, with flame retardants being particularly preferred.

If additives (H) are used, these are amounts of preferably 0.1 to 30 parts by weight, more preferably from 0.1 to 20 parts by weight, in particular from 0.1 to 15 parts by weight, based in each case on 100 parts by weight of siloxane (A) , The preparations according to the invention preferably contain no additives (H). The compositions according to the invention preferably contain no silicone resins, silicone resins meaning siloxanes in which more than 50% of all siloxane units are known Meaning of T units (-Si0 _3/2 ) and Q units (Si0 / ₂ ) have.

The components of the foamable preparation used according to the invention may each be one type of such a component as well as a mixture of at least two types of a particular component.

Preferably, the preparations according to the invention are those containing

(A) organosiloxanes,

(B) polyisocyanates,

possibly

(C) fillers,

possibly

(D) emulsifiers,

possibly

(E) physical blowing agents,

possibly

(F) catalysts,

possibly

(G) chemical blowing agents and

possibly

(H) additives,

wherein the preparations according to the invention contain at least one blowing agent selected from components (E) and (G), in particular at least (G).

Apart from the components (A) and (B), and if appropriate one or more of the components (C) to (H), the preparations according to the invention preferably contain no further constituents. The preparations according to the invention can now be prepared by any desired methods known per se, such as simple mixing of the individual components, it also being possible to prepare premixes of individual constituents. 2-component systems are preferably prepared, the two components of the foamable preparation according to the invention containing all constituents in any desired combinations and proportions, with the proviso that one component does not simultaneously contain siloxanes (A) and polyisocyanates (B) or the constituents (B) and (G).

Another object of the invention is a process for the preparation of the preparations according to the invention, characterized in that 2-component systems are prepared, wherein the two components of the foamable preparation contain all ingredients in any combination and proportions, with the proviso that a component not simultaneously Siloxanes (A) and polyisocyanates (B) or the components (B) and (G) contains.

For example, for the production of the preparation according to invention prefers a mixture containing component (A), if necessary component (C), if necessary component (D), if necessary component (E), if necessary component (F), if necessary component (G) and if necessary component (H ) as component 1 and a component 2 comprising component (B), which are then mixed together to prepare the foam according to the invention. The preparations according to the invention are preferably liquid to viscous and have a viscosity of preferably 250 to

10,000 mPas, more preferably 500 to 5,000 mPas, each at 25 ° C and measured according to AS MD 4283. The preparations according to the invention are preferably used for the production of foams, more preferably of hard or

Flexible foams, in particular soft foams.

Another object of the present invention is a process for the preparation of silicone-containing polyurethane foams, characterized in that siloxanes (A), polyisocyanate (B) and at least one blowing agent are mixed and allowed to react.

In a preferred embodiment of the process according to the invention, siloxane (A), polyisocyanate (B), catalyst (F) and chemical blowing agent (G) and optionally component (C) are mixed and allowed to react in direct connection thereto.

In the method according to the invention, the foamable composition is preferably placed in a mold, which is subsequently sealed so that the overpressure created during foaming can escape. This can e.g. be realized in that the mold has a pressure relief valve or small openings, so incompletely closed, for example, over one or more narrow gaps.

The molds which may be used in the process of the invention may be any of the types of molds heretofore used to make molded foams. Examples of such forms are closable and heatable metal molds which are used to escape the displaced

Air are provided during the foaming process with a pressure relief valve. The molds used according to the invention are preferably heatable molds of a solid material, such as glass fiber reinforced polyester or epoxy resins and metals, such as steel or aluminum, wherein molds made of steel and aluminum preferably with a primer, preferably once before use, are rendered hydrophobic ,

Examples of primer pastes with which the forms used in the process according to the invention can be rendered hydrophobic are high-melting waxes based on hydrocarbons, as are commercially available, for example, from Chem-Trend Deutschland GmbH, D-Maisach under the trade name Klüberpur 55-0005 are available. If desired, the molds can be wetted with a release agent for better releasability of the foam bodies produced.

Examples of such release agents are high-melting waxes dissolved in hydrocarbons, such as those obtainable, for example, from Chemtrend Deutschland GmbH, D-Maisach under the trade name Klüberpur 41-0057.

In the method according to the invention, the molds used are preferably used without release agent.

The molds used in the process according to the invention are adjusted to temperatures of preferably 0 to 150.degree. C., more preferably 10 to 100.degree. C., in particular 40 to 80.degree.

In the process according to the invention, the expansion of the foam as it is formed is limited by the mold used, ie the mold is "overpacked." This overpacking is typically usually between 20% by volume and 100% by volume. Typical filling levels at a target foam density of 50 kg / m ³ are 5% by volume. The heat produced in the reaction according to the invention preferably remains in the system and contributes to the formation of foam. In the method according to the invention reaction temperatures up to preferably 50 to 150 ° C are achieved in the foam core. The process of the invention is preferably carried out at the pressure of the surrounding atmosphere, that is about 900 to 1100 hPa.

In the process according to the invention, preference is given to liberating C0 ₂ , which for the most part is responsible for the structure of the foam structure according to the invention.

In the method according to the invention, the demolding time, ie the time from filling the mold to removing the molded foam from the mold, is preferably 1 to 20 minutes, more preferably 2 to 15 minutes, in particular 3 to 10 minutes.

In the process according to the invention partially closed-cell foams are obtained, which can be converted by the application of an external pressure into completely open-celled foams, such as by the mechanical compression of the foamed bodies by two immediately adjacent free-running rollers, through which Foam body is driven through, wherein it is compressed to preferably over 75%. Another object of the invention are foams, which can be prepared by reacting siloxanes (A) with polyisocyanate (B) and at least one blowing agent. The foams according to the invention are distinguished by a fine, open-cell foam structure. Its mechanical properties correspond to those of commercially available PU foams.

The molded foams of the invention have a density of preferably 10 to 500 kg / m ³ , more preferably 15 to 200 kg / m ³ , in particular 20 to 120 kg / m ³ , in each case determined at 25 ° C. and 1013 hPa.

The foams of the invention have the advantage that they have on the outer sides of compact, defect-free and homogeneous surfaces.

The compositions according to the invention and the process according to the invention for producing foams have the advantage that no release agents are required.

The foamable preparations according to the invention have the advantage that they can be processed in a very simple manner and with the hitherto known methods from PU technology.

Furthermore, the preparations according to the invention have the advantage that they can be prepared with commercially readily available educts.

In addition, the preparations according to the invention have the advantage that they can be prepared without the addition of a solvent, whereby no solution during the manufacturing process. incurred remnants and can be saved with the elimination of solvent removal time and cost.

Furthermore, the preparations according to the invention have the advantage that they are easy to process and can be prepared with low viscosity.

The preparations according to the invention have the advantage that silicone polyurethane foams with low densities can be produced by the one-shot process.

The process according to the invention for the production of silicone-containing PU foams has the advantage that it is easy to use in the

Implementation is.

Furthermore, the foams of the invention have the advantage that they are flexible and extremely flame retardant.

The foams according to the invention also have the advantage that they have high mechanical strengths, in particular in combination with low foam densities.

The foams according to the invention can be used wherever polyurethane foams have hitherto been used. In particular, they are suitable for upholstery.

In the following examples, all parts and percentages are by weight unless otherwise specified. Unless stated otherwise, the following examples are at a pressure of the surrounding atmosphere, ie at about 1000 hPa, and at room temperature, ie about 20 ° C or a temperature, which is obtained when combining the reactants at room temperature without additional heating or Cooling presents, performed. All viscosity data given in the examples should refer to a temperature of 25 ° C. In the examples, the following starting materials were used:

MDI: polymeric MDI with. a functionality of 2.9 (commercially available under the name Suprasec ^® 2085 from Huntsman Polyurethanes, D-Deggendorf);

Toluene diisocyanate: mixture of 2,4- and 2,6-toluene diisocyanate in the ratio 80:20 (commercially available under the name

Desmodur ^® T80 from Bayer MaterialScience AG, D-Leverkusen);

TMXDI: 1,3-bis (1-isocyanato-1-methylethyl) benzene (commercially available from Sigma-Aldrich Chemie GmbH, D-Munich)

iftminkatalysator: diazabicyclooctane (commercially available under the name DABCO ^® Crystal Air Products GmbH, D-Hamburg);

Expanded graphite: Exfoliation graphite with a minimum expansion rate of 350 at a starting temperature of 250 ° C. (commercially available under the name ES 350 F5 from Graphit Kropfmühl AG, D-Hauzenberg);

Wollastonite: Surface-modified, acicular wollastonite having an aspect ratio of 6: 1 (commercially available under the name Tremin 939-304 from Quarzwerke GmbH, D-Frechen);

Calcium hydrogen phosphate: commercially available from Sigma-Aldrich Chemie GmbH, D-Munich

The mold used in the following examples has dimensions of 40cm x 20cm x 5cm and was hydrophobed once before start-up with 25 g of primer paste with the name "Klüberpur 55-0005" from Chem-Trend Germany GmbH, D-Maisach. Comparative Example 1

200.00 g of a linear organopolysiloxane of the formula HO-CH 2 -

[Si (CH ₃ ) ₂ -O] 29Si (CH ₃ ) 2 -CH 2 -OH and 12.8 g of MDI were added under a

Argon atmosphere reacted in 400 ml of absolute acetone. The reaction was catalysed with bismuth (III) neodecanoate (60 mg) and stirred at 50 ° C. After one hour of reaction time, 2.5 g of N-methylethanolamine were slowly added dropwise at first, and then the resulting reaction mixture was freed from the solvent at a pressure of 10 hPa.

200.0 g of the hyperbranched organopolysiloxane thus obtained were first emulsified with 500 mg of diazabicyclooctane and 5.1 g of water through a long-running stirrer to a homogeneous mixture and then 54.4 g of toluene diisocyanate were added to this emulsion and for 10 s with a high-speed stirrer incorporated. From the mixture thus obtained, 200 g was immediately added to a tempered at 70 ° C 4L aluminum mold and the mold for a period of 10 min. was closed except for a 100 μπι wide and 40 cm long gap to escape the air to be displaced. After a demolding time of 10 min. was obtained a silicone PU foam with a density of 50 kg / m ³ , which had a clearly visible inhomogeneous surface. Comparative Example 2

200.00 g of a linear organopolysiloxane of the formula HO-CH 2 -

[Si (CH ₃ ) ₂ -O] 29Si (CH ₃ ) ₂ -CH ₂ -OH and 12.1 g of MDI were added under a

Argon atmosphere reacted in 400 ml of absolute acetone. The reaction was catalysed with bismuth (III) neodecanoate 60 mg and stirred at 50 ° C. After one hour of reaction time, initially 3.0 g of diethanolamine were slowly added dropwise and then freed of the resulting reaction mixture at a pressure of 10 hPa from the solvent. 200.0 g of the hyperbranched organopolysiloxane thus obtained were first emulsified with 500 mg of diazabicyclooctane and 5.1 g of water through a high-speed stirrer to a homogeneous mixture and then 56.7 g of toluene diisocyanate were added to this emulsion and 10 seconds with a long-running stirrer incorporated. From the mixture thus obtained, 200 g was immediately added to a tempered at 70 ° C 4L aluminum mold and the mold for a period of 10 min. was closed except for a 100 μιη wide and 40 cm long gap to escape the air to be displaced. After a demolding time of 10 min. a silicone PU foam having a density of 50 kg / m ^{3 was} obtained. Compared to the foam of Comparative Example 1, a significantly more homogenous surface could be seen here, but the foam surface still had an irregular structure.

example 1

200.00 g of a linear organopolysiloxane of the formula H0-CH ₂ - [Si (CH ₃₎ ₂ -0] ₂₉ Si (CH ₃₎ ₂ -CH ₂ -OH and 12.3 g toluene diisocyanate were absolute under an argon atmosphere in 100 ml Implemented acetone. The reaction was catalysed with bismuth (III) neodecanoate 60 mg and stirred at 50 ° C. After a reaction time of 30 minutes, initially 5.0 g of diethanolamine were slowly added dropwise and then the reaction mixture obtained was freed from the solvent at a pressure of 10 hPa.

180.0 g of the organopolysiloxane thus obtained were first emulsified with 600 mg of diazabicyclooctane and 6.30 g of water through a high-speed stirrer to a homogeneous mixture and then 65.4 g of toluene diisocyanate were added to this emulsion and incorporated for 10 s with a high-speed stirrer , Of the mixture thus obtained, 200 g of was placed in a tempered to 70 ° C 4L aluminum mold and the mold was sealed for a period of 10 minutes to a 100 μτη wide and 40 cm long and 40 cm long gap to escape the air to be displaced. After a demolding time of 10 minutes, a silicone PU foam with a density of 50 kg / m ^{3 was} obtained, which had a homogeneous and defect-free surface.

Example 2

200.00 g of a linear organopolysiloxane of the formula HO-CH ₂ -

[Si (CH ₃ ) 2-0] 29S1 (CH ₃ ) ₂ -CH ₂ -OH and 12.3 g of toluene diisocyanate were reacted without solvent under argon atmosphere. The reaction was catalyzed with bismuth (III) neodecanoate 20 mg and stirred at 50 ° C. After a reaction time of 30 minutes, initially 5.0 g of diethanolamine were slowly added dropwise and then the resulting reaction mixture was cooled to room temperature.

180.0 g of the organopolysiloxane thus obtained were first emulsified with 600 mg of diazabicyclooctane and 6.30 g of water through a high-speed stirrer to a homogeneous mixture and then 65.4 g of toluene diisocyanate were added to this emulsion and incorporated for 10 s with a high-speed stirrer , From the mixture thus obtained, 200 g were immediately placed in a tempered to 70 ° C 4L aluminum mold and the mold for a period of 10 min to a 100 μτη wide and 40 cm long and 40 cm long gap to escape the air to be displaced was closed. After a demolding time of 10 minutes, a silicone PU foam with a density of 50 kg / m ^{3 was} obtained, which had a homogeneous and defect-free surface. Example 3

200.00 g of a linear organopolysiloxane of the formula HO-CH ₂ - [Si (CH ₃₎ 2-0] ₂ GSi (CH ₃₎ 2 ~ _CH2-OH and 12.3 g toluene diisocyanate were reacted without solvent, under an argon atmosphere. The reaction was catalyzed with bismuth (III) neodecanoate 20 mg and stirred at 50 ° C. After a reaction time of 30 minutes, initially 5.0 g of diethanolamine were slowly added dropwise and then the resulting reaction mixture was cooled to room temperature. 180.0 g of the organopolysiloxane thus obtained were first emulsified with 600 mg of diazabicyclooctane and 7.20 g of water through a schneiHäufenden stirrer to a homogeneous mixture and then 73.2 g of toluene diisocyanate were added to this emulsion and incorporated for 10 s with a high-speed stirrer , Of the mixture thus obtained, 180 g were immediately put into a tempered 4L aluminum mold heated to 70 ° C and the mold for a period of 10 min. was closed to a 100 μτη wide and 40 cm long and 40 cm long gap to escape the air to be displaced. After a demolition time of 10 min. was a silicone PU foam with a

Density of 45 kg / m ³ obtained, which had a homogeneous and defect-free surface.

Example 4

200.00 g of a linear organopolysiloxane of the formula H0-CH ₂ -

[Si (CH ₃ ) 2-0] 29S1 (CH ₃ ) ₂ -CH ₂ -OH and 12.3 g of toluene diisocyanate were reacted without solvent under argon atmosphere. The reaction was catalyzed with bismuth (III) neodecanoate 20 mg and stirred at 50 ° C. After a reaction time of 30 minutes, initially 6.0 g of diethanolamine were slowly added dropwise, and the reaction mixture thus obtained was cooled to room temperature. 180.0 g of the organopolysiloxane thus obtained were first emulsified with 600 mg of diazabicyclooctane and 6.30 g of water through a high-speed stirrer to a homogeneous mixture and then 67.2 g of toluene diisocyanate were added to this emulsion and incorporated for 10 s with a high-speed stirrer , From the mixture thus obtained, 200 g was immediately added to a tempered at 70 ° C 4L aluminum mold and the mold for a period of 10 min. was closed to a 100 μτη wide and 40 cm long and 40 cm long gap to escape the air to be displaced. After a demoulding time of 10 min. was obtained a silicone PU foam with a density of 50 kg / m ³ , which had a homogeneous and defect-free surface. Example 5

200.00 g of a linear organopolysiloxane of the formula HO-CH ₂ - [Si (CH ₃₎ 2-0] ₂₉ Si (CH ₃₎ 2 -CH ₂ -OH and 12.3 g toluene diisocyanate were reacted without solvent, under an argon atmosphere. The reaction was catalyzed with bismuth (III) neodecanoate 20 mg and stirred at 50 ° C. After a reaction time of 30 minutes, initially 6.0 g of diethanolamine were slowly added dropwise, and the reaction mixture thus obtained was cooled to room temperature.

180.0 g of the organopolysiloxane thus obtained were first emulsified with 600 mg of diazabicyclooctane and 7.20 g of water through a high-speed stirrer to a homogeneous mixture and then 75.0 g of toluene diisocyanate were added to this emulsion and incorporated for 10 s with a high-speed stirrer , 200 g of the mixture thus obtained were immediately poured into a 4L aluminum mold heated to 70 ° C. and the mold was heated for a period of 10 minutes. was closed to a 100 pm wide and 40 cm long and 40 cm long gap to escape the air to be displaced. After a decision forming time of 10 min. was obtained a silicone PU foam with a density of 45 kg / m ³ , which had a homogeneous and defect-free surface. Example 6

200.00 g of a linear organopolysiloxane of the formula HO-CH ₂ - [Si (CH ₃₎ ₂ -0] ₃₇ Si (CH ₃₎ ₂ -CH ₂ -OH were and 9.8 g toluene diisocyanate reacted without solvent, under an argon atmosphere. The reaction was catalyzed with bismuth (III) neodecanoate 20 mg and stirred at 50 ° C. After a reaction time of 30 minutes, initially 5.4 g of diethanolamine were slowly added dropwise, and then the resulting reaction mixture was cooled to room temperature.

180.0 g of the organopolysiloxane thus obtained were first emulsified with 600 mg of diazabicyclooctane and 7.20 g of water through a high-speed stirrer to give a homogeneous mixture and then 74.6 g of toluene diisocyanate were added to this emulsion and incorporated for 10 s with a high-speed stirrer , 200 g of the mixture thus obtained were immediately poured into a 4L aluminum mold heated to 70 ° C. and the mold was heated for a period of 10 minutes. was closed to a 100 μτη wide and 40 cm long and 40 cm long gap to escape the air to be displaced. After a demoulding time of 10 min. was obtained a silicone PU foam with a density of 45 kg / m ³ , which had a homogeneous and defect-free surface.

Example 7

200.00 g of a linear organopolysiloxane of the formula H0-CH ₂ - [Si (CH ₃₎ 2-0] ₃₇ Si (CH ₃₎ ₂ -CH ₂ -OH and 9.8 g toluene diisocyanate were reacted without solvent, under an argon atmosphere. The reaction was catalyzed with bismuth (III) neodecanoate 20 mg and stirred at 50 ° C. After 30 min reaction time were initially slowly added dropwise 5.4 g of diethanolamine and then cooled the resulting reaction mixture to room temperature.

160.0 g of the organopolysiloxane thus obtained were first emulsified with 600 mg of diazabicyclooctane and 6.40 g of water through a schneiHäufenden stirrer to a homogeneous mixture and then 20.0 g of expandable graphite and 66.3 g of toluene diisocyanate were added to this emulsion and incorporated for 10 s with a high-speed stirrer. From the mixture thus obtained, 200 g were immediately placed in a tempered at 70 ° C 4L aluminum mold and the mold for a period of 10 min. was closed to a 100 μτη wide and 40 cm long and 40 cm long gap to escape the air to be displaced. After a demolding time of 10 min. a gray silicone PU foam was obtained with a density of 45 kg / m ³ , which had a homogeneous and defect-free surface.

Example 8

200.00 g of a linear organopolysiloxane of the formula H0-CH ₂ - [Si (CH ₃₎ 2-0] 37S1 (CH ₃₎ 2 CH ₂ -OH and 9.8 g toluene diisocyanate were reacted without solvent, under an argon atmosphere. The reaction was catalyzed with bismuth (III) neodecanoate 20 mg and stirred at 50 ° C. After a reaction time of 30 minutes, initially 5.4 g of diethanolamine were slowly added dropwise, and then the resulting reaction mixture was cooled to room temperature.

160.0 g of the organopolysiloxane thus obtained were first emulsified with 600 mg of diazabicyclooctane and 6.40 g of water through a high-speed stirrer to a homogeneous mixture and then 10.0 g of expandable graphite, 10.0 g of wollastonite and 66.3 g of toluene diisocyanate added to this emulsion and incorporated for 10 s with a high-speed stirrer. Of the so obtained mixture, 200 g were immediately placed in a heated to 70 ° C 4L aluminum mold and the mold for a period of 10 min. was closed except for a 100 μπι wide and 40 cm long and 40 cm long gap to escape the air to be displaced. After a demolding time of 10 min. a gray silicone PU foam was obtained with a density of 45 kg / m ³ , which had a homogeneous and defect-free surface. Example 9

200.00 g of a linear organopolysiloxane of the formula HO-CH ₂ - [Si (CH ₃₎ 2-0] ₃₇ Si (CH ₃₎ ₂ -CH ₂ -OH and 13, 7 g of TMXDI reacted without solvent, under an argon atmosphere. The reaction was catalysed with bismuth (III) neodecanoate 50 mg and stirred at 50 ° C. After a reaction time of 30 minutes, initially 5.4 g of diethanolamine were slowly added dropwise, and then the resulting reaction mixture was cooled to room temperature.

160.0 g of the organopolysiloxane thus obtained were first emulsified with 600 mg of diazabicyclooctane and 6.40 g of water through a high-speed stirrer to a homogeneous mixture and then 10.0 g of expanded graphite, 5.0 g of wollastonite and 5.0 g of calcium hydrogen phosphate and 66.1 g of toluene diisocyanate added to this emulsion and incorporated for 10 s with a fast-running stirrer. From the mixture thus obtained, 200 g was immediately added to a tempered at 70 ° C 4L aluminum mold and the mold for a period of 10 min. was closed to a 100 μτη wide and 40 cm long and 40 cm long gap to escape the air to be displaced. After a demolding time of 10 min. a gray silicone PU foam was obtained with a density of 45 kg / m ³ , which had a homogeneous and defect-free surface.

Claims

claims

1. containing foamable compositions

(A) siloxanes of the formula

wherein

R may be the same or different and is hydrogen or a monovalent, optionally substituted hydrocarbon radical,

X may be the same or different and represents -O-, -S- or -NR ⁴ -,

R ⁴ is hydrogen or monovalent, optionally substituted hydrocarbon radical,

n may be the same or different and an integer greater than or equal to 1 means and

m is an integer greater than or equal to 1,

with the proviso that at least one radical R ³ in formula (I) the

Meaning of optionally substituted hydrocarbon has at least one hydroxyl group and / or thiol group,

and

(B) polyisocyanates.

2. Foamable compositions according to claim 1, characterized in that X is -O-.

3. Foamable compositions according to claim 1 or 2, characterized in that radical R ³ is hydroxyalkyl radicals having 1 to 6 carbon atoms. , Foamable compositions according to one or more of claims 1 to 3, characterized in that in formula (I) both radicals R ^{3 have} hydroxyl groups.

5. Foamable compositions according to one or more of claims 1 to 4, characterized in that it contains such

(A) organosiloxanes,

(B) polyisocyanates,

possibly

(C) fillers,

possibly

(D) emulsifiers,

possibly

(E) physical blowing agents,

possibly

(F) catalysts,

possibly

(G) chemical blowing agents and

possibly

(H) additives wherein the preparations according to the invention contain at least one blowing agent selected from components (E) and (G). 6. siloxanes of the formula

wherein

X may be the same or different and represents -O-, -S- or -NR ⁴ -,

R ⁴ is hydrogen or monovalent, optionally substituted hydrocarbon radical,

m is an integer greater than or equal to 1, with the proviso that at least one radical R ³ in formula (I) has the meaning of optionally substituted hydrocarbon radical and has at least one hydroxyl group and / or thiol group.

7. A process for the preparation of the foamable compositions according to one or more of claims 1 to 5, characterized in that 2-component systems are prepared, wherein the two components of the foamable preparation contain all components in any combination and proportions, with the proviso in that one component does not simultaneously contain siloxanes (A) and polyisocyanates (B) or components (B) and (G). 8. A process for the preparation of silicone-containing polyurethane foams, characterized in that siloxanes (A), polyisocyanate (B) and at least one blowing agent are mixed and allowed to react. 9. foams, preparable by reaction of siloxanes (A) with polyisocyanate (B) and at least one blowing agent.