DE102019200446A1 - Poly-OH-functional trisiloxanes, their production and their use for the production of polyurethane foams - Google Patents

Abstract

A poly-OH-functional trisiloxane is described which corresponds to the general formula (1), where purely branched or linear polyoxyalkylene radical, preferably polyoxyethylene polyoxypropylene radical, which carries at least 2 free OH groups which are reactive toward isocyanates.

Description

The present invention is in the field of polyether siloxanes, foams and polyurethane foams

It relates in particular to poly-OH-functional trisiloxanes and their use for the production of polyurethane foams, preferably for the production of polyurethane foams which have been produced using supercritical CO ₂ as blowing agent.

Polyurethane foams with medium pore sizes (arithmetic mean) in the nanometer range are characterized by an extremely low thermal conductivity and are therefore regarded as extremely efficient high-performance insulation materials. However, it has not yet been possible to manufacture such materials on an industrial scale, since suitable manufacturing processes have hitherto not been known. The "Principle of Supercritical Microemulsion Expansion" (POSME for short, see DE 10260815 B4 ) represents an innovative approach to the production of nanoporous foams, which could enable the production of polyurethane nanofoams in the future. The core idea of this process is to use blowing agent-based microemulsions as the starting system for foam production. Due to the fact that in such microemulsions the blowing agent is dispersed in the form of nanometer-sized droplets (droplet diameter ≈ 1 - 10 nm), when these systems are expanded and polymerized at the same time, it is in principle possible for the blowing agent droplets to also be only nanometer-sized foam bubbles ( grow Ø ≈ 10 ² nm). In order to ensure a uniform swelling of the blowing agent droplets, supercritical fluids, such as supercritical CO ₂ (abbreviated to sc CO ₂ ), are preferably used in the context of the POSME method. This offers the advantage that the blowing agent does not undergo a phase transition from liquid to gaseous during the expansion of the microemulsion, as a result of which the density of the blowing agent decreases continuously and not abruptly during the expansion.

It has already been shown in the past that the POSME process can in principle be applied to the production of polyurethane-based foams (see e.g. DE 102009053218 A1 ). This includes the formulation of polyol-scCO ₂ microemulsions, which are reacted with isocyanate in the further process and then expanded. In this way, it was already possible in the past to produce polyurethane foams with pore sizes in the single-digit micrometer range. In this context, however, it should be noted that both the stabilization of the polyol-scCO ₂ microemulsions and the stabilization of the polyurethane foam subsequently formed have to be added to the system, in some cases in concentrations of more than 10% by weight. In the past, trisiloxane-based surfactants have proven their worth because they enable scCO ₂ to be efficiently solubilized in polyols. The trisiloxanes used so far have always been mono-OH functional. A disadvantage of this class of surfactants, however, is that they act as chain end stoppers during the polyurethane reaction. Especially at high surfactant concentrations, this leads to a significant deterioration in the mechanical properties of the polyurethane foams produced in this way. For example, the compression hardness of the foam is significantly reduced by using high concentrations of mono-OH functional surfactants. However, good mechanical foam properties are required for the use of polyurethane nanofoams, for example as insulation material.

The object of the present invention was therefore to provide surfactants which can be used in the context of the POSME process for the production of polyurethane (nano) foams, but which have no or only a slight influence on the mechanical foam properties.

Surprisingly, it was found that poly-OH-functional trisiloxanes according to claim 1 enable the present object to be achieved. The poly-OH-functional trisiloxanes according to the invention surprisingly have manifold advantages.

An advantage of the poly-OH-functional trisiloxanes according to the invention is that they enable a particularly efficient solubilization of scCO ₂ in polyols as part of the POSME process, as a result of which the amount of surfactant required to provide stable polyol scCO ₂ microemulsions is low can be held.

Another advantage of the poly-OH-functional trisiloxanes according to the invention is that they have a particularly good foam-stabilizing effect when forming a polyurethane foam and thus enable the production of fine-celled, homogeneous foams.

Another advantage of the poly-OH-functional trisiloxanes according to the invention is that they do not act as chain end stoppers during the polyol-isocyanate reaction and thus enable adequate crosslinking of the polyurethane polymer structure even at high surfactant concentrations. This in turn has a positive effect on the mechanical properties of the polyurethane foams produced, such as their compression hardness.

For the purposes of the present invention, the term trisiloxane encompasses polyether-modified 1,1,1,3,5,5,5-heptamethyltrisiloxanes (HMTS for short). If technical HMTS is used to produce appropriate surfactants, this can contain 1,1,1,3,5,7,7,7-octamethyltetrasiloxane (OMTS). The term trisiloxane therefore also includes mixtures of polyether-modified HMTS and polyether-modified OMTS.

For the purposes of the present invention as a whole, the term polyether encompasses polyoxyalkylenes, polyoxyethylene and polyoxypropylene and polyoxyethylene-polyoxypropylene mixed polyethers being particularly preferred. Mixed polyethers can be constructed both statistically and in blocks. In this context, statistical structure means that the monomer units of the polyether are distributed in a random order over the polyether chain, whereas a polyether built up in blocks consists of defined monomer blocks. The polyethers in the sense of the present can be both linear and branched. Mono-OH-functional polyethers are here polyethers which have exactly one free OH group which is reactive towards isocyanates, poly-OH-functional polyethers have two or more free OH groups which are reactive towards isocyanates.

For the purposes of the entire present invention, the term microemulsion encompasses macroscopically homogeneous, thermodynamically stable, microstructured ternary mixtures of a polar (for example a polyol or a polyol mixture), an apolar (for example scCO ₂ ) and an amphiphilic component (for example a trisiloxane) which the is capable of solubilizing the other two, intrinsically immiscible components. The microstructure of microemulsions can be demonstrated, for example, by scattering methods such as dynamic light scattering, small-angle neutron scattering or small-angle X-ray scattering. The term microemulsion is generally known to the person skilled in the art and is described, for example, in Strey et al., Colloid and Polymer Science, 1994, 272, 1005 or Kahlweit et al, Angewandte Chemie Int. Ed., 1985, 24, 654 described in detail.

For the purposes of the entire present invention, the term supercritical fluid encompasses fluids which are above their critical point, which means that they cannot be liquefied by increasing the pressure and thus do not undergo a liquid-gas phase transition during isothermal expansion or compression processes. This also includes a continuous, non-abrupt change in their compression / expansion density. For example, CO ₂ becomes supercritical at pressures> 73.8 bar and temperatures> 31 ° C. The term near-critical fluid encompasses fluids which are only a few degrees (preferably less than 30 ° C., more preferably less than 20 ° C., even more preferably less than 10 ° C.) below their critical point. In the case of compression / expansion, such fluids undergo a liquid-gas phase transition, but the sudden change in density associated therewith is only slight. Both terms are generally known to the person skilled in the art.

The poly-OH-functional trisiloxane surfactants according to the invention can preferably be prepared by hydrosilylating hepamethyl-trisiloxanes with poly-OH-functional polyethers which have at least one double bond which is reactive towards Si-H functions. The chemical reactions on which this production is based are known in the specialist literature and are described there in detail (see, for example, Silicones - Chemistry and Technology, Vulkan-Verlag Essen, 1989).

The invention is described further and by way of example below, without the invention being restricted to these exemplary embodiments. If areas, general formulas or classes of compounds are given below, these should not only include the corresponding areas or groups of compounds that are explicitly mentioned, but also all sub-areas and sub-groups of compounds that are obtained by removing individual values (areas) or compounds can be. If documents are cited in the context of the present description, their content, in particular in relation to the facts in the context in which the document was cited, should completely belong to the disclosure content of the present invention. Unless otherwise stated, percentages are percentages by weight. If parameters are specified below that were determined by measurement, the measurements were carried out, unless otherwise stated, at a temperature of 25 ° C. and a pressure of 101,325 Pa. If chemical (sum) formulas are used in the present invention, the indicated indices can represent both absolute numbers and mean values. In the case of polymeric compounds, the indices preferably represent mean values Structure and empirical formulas represented by the invention represent all isomers conceivable by different arrangement of the repeating units. Are within the scope of the present invention compounds such. B. polyethers, siloxanes or polyether siloxanes, described, which can have different units several times, they can be randomly distributed (statistical oligomer or polymer), ordered (block oligomer or block polymer) or occur as a gradient distribution in these compounds.

wobei der Rest R¹ ein verzweigter oder linearer Polyoxyalkylenrest, bevorzugt ein Polyoxyethylenpolyoxypropylenrest ist, welcher mindestens 2 freie, gegenüber Isocyanaten reaktive OH-Gruppen trägt.The present invention relates to poly-OH-functional trisiloxanes which correspond to the general formula (1):

wherein the radical R ^{1 is} a branched or linear polyoxyalkylene radical, preferably a polyoxyethylene polyoxypropylene radical, which carries at least 2 free OH groups which are reactive toward isocyanates.

M' = _1/2O-R⁴

• a = 2 bis 50, bevorzugt 2 bis 25, insbesondere bevorzugt 2 bis 10,
• b = 2 bis 50, bevorzugt 2 bis 25, insbesondere bevorzugt 2 bis 10,
• c = 0 bis 25, bevorzugt 0 bis 10, insbesondere bevorzugt 1 bis 5
• d = 1-3 und
• R² ein einwertiger linearer oder verzweigter Alkylrest mit 1 bis 20 Kohlenstoffatomen, der eine gegenüber Wasserstoffsiloxanen hydrosilierbare Doppelbindung enthält, bevorzugt ein (Meth)allyl-Rest, ein Rest basierend auf Trimethylolpropan-mono(meth)allylether oder ein Rest basierend auf Pentaerythritylmono(meth)allylether ist,
• R³ ein einwertiger aliphatischer oder aromatischer Kohlenwasserstoffrest mit 1 bis 20 Kohlenstoffatomen oder H, bevorzugt ein Methylrest oder H ist,
• R⁴ ein einwertiger aliphatischer gesättigter oder ungesättigter Kohlenwasserstoffrest mit 1 bis 20 Kohlenstoffatomen oder H, bevorzugt H ist und
• R⁵ unabhängig voneinander gleiche oder verschiedene einwertige aliphatische gesättigte oder ungesättigte Kohlenwasserstoffreste mit 1 bis 20 Kohlenstoffatomen sind, wobei insbesondere Methylreste bevorzugt sind,

unter der Maßgabe, dass der Polyether mindestens zwei freie, gegenüber NCO-Gruppen reaktive OH-Funktionen aufweist.In a preferred embodiment of the present invention, the polyoxyalkylene radical R ^{1 is derived} from a polyether of the general formula (2), which can be converted by hydrosilylation with HMTS to a poly-OH-functional trisiloxane of the general formula (1): MM ' _a D _b T _c Formula (2) where M = R1 ^2- (O _1/2 ) d, preferred

M '= _1/2 OR ⁴

• a = 2 to 50, preferably 2 to 25, particularly preferably 2 to 10,
• b = 2 to 50, preferably 2 to 25, particularly preferably 2 to 10,
• c = 0 to 25, preferably 0 to 10, particularly preferably 1 to 5
• d = 1-3 and
• R ^{2 is} a monovalent linear or branched alkyl radical having 1 to 20 carbon atoms, which contains a double bond which can be hydrosilated with respect to hydrogen siloxanes, preferably a (meth) allyl radical, a radical based on trimethylolpropane mono (meth) allyl ether or a radical based on pentaerythrityl mono (meth ) is allyl ether,
• R ^{3 is} a monovalent aliphatic or aromatic hydrocarbon radical having 1 to 20 carbon atoms or H, preferably a methyl radical or H,
• R ^{4 is} a monovalent aliphatic saturated or unsaturated hydrocarbon radical having 1 to 20 carbon atoms or H, preferably H and
• R ^{5 are,} independently of one another, identical or different monovalent aliphatic saturated or unsaturated hydrocarbon radicals having 1 to 20 carbon atoms, methyl radicals in particular being preferred,

with the proviso that the polyether has at least two free OH functions which are reactive toward NCO groups.

The structural elements M, M ', D and T are each linked via oxygen bridges. Two O _1/2 residues are always linked to form an oxygen bridge (-O-), whereby an O _1/2 residue can only be linked to another O _1/2 residue.

It corresponds to a particularly preferred embodiment of the present invention if the polyethers of the general formula (2) are prepared by reacting (meth) allyl alcohol with alkylene oxides, preferably ethylene oxide and propylene oxide, and at least one further epoxide which contains one or more free OH Group carries, here glycidol or glycidol-glycidyl ether are particularly preferred. It is further preferred if isopropylidene-glyceryl-glycidyl ether (ketal-protected derivative of glycidol-glycidyl ether) is used as a further synthesis building block for the synthesis. This also corresponds to a particularly preferred embodiment of the present invention. By incorporating this monomer into the polyether chain and subsequent deprotection (acetone elimination), further free OH groups can be formed.

It also corresponds to a preferred embodiment of the present invention if higher-quality, (meth) allyl-modified starting alcohols which have two or more OH functions are used for the synthesis of the polyethers of the general formula (2). Glycerol mono (meth) allyl ether, trimethylolpropane mono (meth) allyl ether and pentaerythrityl mono (meth) allyl ether are particularly preferred. These can subsequently be reacted with alkylene oxides, preferably ethylene oxide and propylene oxide, and optionally further epoxides which carry an additional free OH group, preferably glycidol or glycidol-glycidyl ether. In this case too, isopropylidene-glyceryl-glycidyl ether can be used as a further building block. This also corresponds to a particularly preferred embodiment of the present invention.

wobei

• e = 0 bis 50, bevorzugt 1 bis 25, besonders bevorzugt 2 bis 10
• f = 0 bis 50, bevorzugt 0 bis 25, besonders bevorzugt 0 bis 10
• g = 0 bis 50, bevorzugt 0 bis 25, besonders bevorzugt 0 bis 10 und
• R³ ein einwertiger aliphatischer oder aromatischer Kohlenwasserstoffreste mit 1 bis 20 Kohlenstoffatomen, bevorzugt ein Methylrest oder H ist und R⁵ unabhängig voneinander gleiche oder verschiedene einwertige aliphatische gesättigte oder ungesättigte Kohlenwasserstoffreste mit 1 bis 20 Kohlenstoffatomen sind, wobei insbesondere Methylreste bevorzugt sind.

In a very particularly preferred embodiment of the present invention, the polyoxyalkylene radical R ^{1 is derived} from a (meth) allyl-modified polyether of the general formula (3), which is converted to a poly-OH-functional trisiloxane of the general formula (1) by hydrosilylation with HMTS can be:

in which

• e = 0 to 50, preferably 1 to 25, particularly preferably 2 to 10
• f = 0 to 50, preferably 0 to 25, particularly preferably 0 to 10
• g = 0 to 50, preferably 0 to 25, particularly preferably 0 to 10 and
• R ^{3 is} a monovalent aliphatic or aromatic hydrocarbon radicals having 1 to 20 carbon atoms, preferably a methyl radical or H and R ^{5 are} independently the same or different monovalent aliphatic saturated or unsaturated hydrocarbon radicals having 1 to 20 carbon atoms, methyl radicals in particular being preferred.

In einer weiteren bevorzugten Ausführungsform der vorliegenden Erfindung sind die Polyether der allgemeinen Formel (3) erhältlich durch die Alkoxylierung von (Meth)Allylalkohol und anschließendem Umsetzung mit einem Äquivalent Glycidol („Glycidol-Endtipping“). Ein entsprechendes Reaktionsschema ist exemplarisch in Formel (5) dargestellt. Hierbei gilt es zu beachten, dass bei der Anlagerung von Glycidol aus statistischen Gründen auch mehrere Glyidcol-Einheiten an eine Polyether-Kette anlagert werden können, woraus Terminal Verzweigungen sowie höhere OH-Funktionalitäten des Polyethers resultieren können (nicht dargestellt in Formel (5)).

In a further particularly preferred embodiment of the present invention, the polyethers of the general formula (3) are obtainable by alkoxylation of 2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane, preferably with ethylene oxide and propylene oxide, followed by a reaction with ( Meth) allyl chloride and subsequent acidic deprotection of the 2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane residue (elimination of acetone). A corresponding reaction scheme is exemplified in formula (4)

In a further preferred embodiment of the present invention, the polyethers of the general formula (3) can be obtained by the alkoxylation of (meth) allyl alcohol and subsequent reaction with an equivalent of glycidol (“glycidol endtipping”). A corresponding reaction scheme is exemplified in formula (5). It should be noted here that when adding glycidol, for statistical reasons, several glyidcol units can also be attached to a polyether chain, which can result in terminal branches and higher OH functionalities of the polyether (not shown in formula (5)) .

wobei

• h = 0 bis 50, bevorzugt 1 bis 25, besonders bevorzugt 2 bis 10
• i = 0 bis 50, bevorzugt 0 bis 25, besonders bevorzugt 0 bis 10
• j = 0 bis 50, bevorzugt 0 bis 25, besonders bevorzugt 0 bis 10
• k = 1 bis 10, bevorzugt 1 bis 6, besonders bevorzugt 1 bis 3, ganz besonders bevorzugt 1 und
• R⁵ unabhängig voneinander gleiche oder verschiedene einwertige aliphatische gesättigte oder ungesättigte Kohlenwasserstoffreste mit 1 bis 20 Kohlenstoffatomen sind, wobei insbesondere Methylreste bevorzugt sind.

Also preferred according to the invention are higher-quality, poly-OH-functional trisiloxanes which can be obtained by hydrosilylating HMTS with at least one polyether of the general formula (6)

in which

• h = 0 to 50, preferably 1 to 25, particularly preferably 2 to 10
• i = 0 to 50, preferably 0 to 25, particularly preferably 0 to 10
• j = 0 to 50, preferably 0 to 25, particularly preferably 0 to 10
• k = 1 to 10, preferably 1 to 6, particularly preferably 1 to 3, very particularly preferably 1 and
• R ^{5 are} independently the same or different monovalent aliphatic saturated or unsaturated hydrocarbon radicals having 1 to 20 carbon atoms, methyl radicals in particular being preferred.

Polyethers of the general formula (6) can preferably be prepared by reacting 2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane with alkenyl oxides, preferably ethylene oxide and propylene oxide, and also allyl glycidyl ether and subsequent deprotection of 2,2-dimethyl -4-hydroxymethyl-1,3-dioxolane residue (elimination of acetone). A corresponding reaction scheme is exemplified in formula (7). It is preferred here if the polyethers have a block-like structure in which the allyl glycidyl ether units are attached to the end of the polyether chain.

As already described, the poly-OH-functional trisiloxanes according to the invention are suitable for the production of polyurethane foams, in particular if a near or supercritical fluid, preferably near or supercritical CO ₂ , is used as a blowing agent for the production of the polyurethane foams. Polyurethane foams and formulations suitable for the production of polyurethane foams containing the poly-OH-functional trisiloxanes according to the invention, in particular those containing a near or supercritical fluid, preferably near or supercritical CO ₂ , are thus also an object of the present invention. Corresponding foams can be used, for example, as insulation or absorber materials.

In this context, the term polyurethane foam denotes foams which are formed by reacting polyisocyanates with them with respect to reactive compounds, preferably with OH groups (“polyols”) and / or NH groups. Polyols for the production of corresponding foams are known per se. Particularly suitable polyols for the purposes of this invention are all organic substances with several isocyanate-reactive groups and their preparations. Preferred polyols are all polyether polyols and polyester polyols commonly used for the production of polyurethane foams. Polyether polyols are obtained by reacting polyhydric alcohols or amines with alkylene oxides. Polyester polyols are based on esters of polyvalent carboxylic acids (usually phthalic or terephthalic acid) with polyhydric alcohols (mostly glycols).

Isocyanates for the production of polyurethane foams are also known per se. The isocyanate component preferably has one or more organic isocyanates with two or more isocyanate functions. Suitable isocyanates for the purposes of this invention are e.g. B. all multifunctional organic isocyanates, such as 4,4'-diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI).

The ratio of isocyanate to polyol, expressed as the NCO index, in the context of the present invention is preferably in the range from 40 to 500, preferably 60 to 350, particularly preferably 80-120. The NCO index describes the ratio of isocyanate actually used to calculated isocyanate (for a stoichiometric reaction with polyol). An NCO index of 100 stands for a molar ratio of the reactive groups of 1 to 1.

In addition to the poly-OH-functional trisiloxanes according to the invention, the polyurethane foams can also contain other additives and additives, such as, for example, fillers, blowing agents, catalysts, organic and inorganic pigments, stabilizers, such as, for example, hydrolysis or UV stabilizers, antioxidants, absorbers, crosslinking agents, dyes or Thickener / rheology additives included.

wobei

• o = 0 bis 50, bevorzugt 1 bis 25, besonders bevorzugt 1 bis 15
• p = 0 bis 250, bevorzugt 5 bis 150, besonders bevorzugt 5 bis 100
• wobei R⁷ unabhängig voneinander gleiche oder verschiedene einwertige aliphatische oder aromatische Kohlenwasserstoffreste mit 1 bis 20 Kohlenstoffatomen, bevorzugt mit 1 bis 10 Kohlenstoffatomen, ganz besonders bevorzugt Methlyreste sind,
• und wobei die Reste R⁸ unabhängig voneinander gleiche oder verschiedene Polyoxyalkylenreste, vorzugsweise Polyoxyethylenpolyoxypropylenreste, sind, und wobei die Reste R⁹ entweder R⁷ oder R⁸ entsprechen. Besonders bevorzugt sind die Reste R⁸ Polyoxyethylenpolyoxypropylenreste mit 5 - 100, bevorzugt mit 7 - 75, ganz besonders bevorzugt mit 10 - 50 Wiederholungseinheiten, wobei das Verhältnis von Polyoxyethlyen- zu Polyoxypropyleneinheiten zwischen 100 : 0 und 0 : 100 liegen kann.

In addition to the inventive poly-OH-functional trisiloxanes, at least one further polyether siloxane of the general formula (6) can also be used as an additive for the production of the polyurethane foams according to the invention:

in which

• o = 0 to 50, preferably 1 to 25, particularly preferably 1 to 15
• p = 0 to 250, preferably 5 to 150, particularly preferably 5 to 100
• where R ^{7 are} independently the same or different monovalent aliphatic or aromatic hydrocarbon radicals having 1 to 20 carbon atoms, preferably having 1 to 10 carbon atoms, very particularly preferably methyl radicals,
• and wherein the R ⁸ radicals are independently the same or different polyoxyalkylene radicals, preferably polyoxyethylene polyoxypropylene radicals, and wherein the R ⁹ radicals correspond to either R ⁷ or R ⁸ . The R ⁸ radicals are particularly preferably polyoxyethylene polyoxypropylene radicals having 5-100, preferably 7-75, very particularly preferably 10-50 repeating units, the ratio of polyoxyethylene to polyoxypropylene units being between 100: 0 and 0: 100.

Gel catalysts which catalyze the polyurethane reaction between isocyanate and polyol are particularly suitable as catalysts for the production of polyurethane foams in the sense of the present invention, in particular those which contain a near or supercritical fluid as blowing agent. These can be selected from the class of amine catalysts, e.g. Triethylamine, dimethylcyclohexylamine, tetramethylethylenediamine, tetramethylhexanediamine, pentamethyldiethylenetriamine, pentamethyldipropylenetriamine, triethylenediamine, dimethylpiperazine, 1,2-dimethylimidazole, N-ethylmorpholine, tris (dimethylaminopropyl) hexahydroethyl, 1,3-methylaminoethanol, 1,3-methylahydro-1-methylahydro-1, 8-Diazabicyclo [5.4.0] undec-7-en, the class of metal catalysts, such as Tin laurate, tin octoate, tin neodecanoate, bismuth-based catalysts as well as nickel and copper acetylacetonate, as well as mixtures of these substances. In the case of polyurethane foams, thermolatent catalysts, that is to say catalysts which only develop their effectiveness above a certain activation temperature and thus allow the foams to cure more slowly, have been particularly united.

1. a) Bereitstellen einer Mischung bestehend aus mindestens einem Polyol, mindestens einem nahe- oder überkritischen Fluid, vorzugsweise scCO₂, mindestens einem erfindungsgemäßen poly-OH-funktionellen Trisiloxan sowie ggf. weiteren Komponenten unter erhöhtem Druck, vorzugsweise bei Drücken von größer 75 bar, mehr bevorzugt von größer 80 bar, noch mehr bevorzugt von größer 100 bar, noch mehr bevorzugt von größer 120 bar, ganz besonders bevorzugt von größer 150 bar.
2. b) Beimischen von Isocyanat
3. c) Expansion der Mischung auf Atmosphärendruck zu einem Polyurethanschaum

As already described, polyurethane foams containing poly-OH-functional trisiloxanes are also the subject of the present invention. The polyurethane foams according to the invention can preferably be produced by a process comprising the steps

1. a) providing a mixture consisting of at least one polyol, at least one near or supercritical fluid, preferably scCO ₂ , at least one poly-OH-functional trisiloxane according to the invention and optionally other components under increased pressure, preferably at pressures greater than 75 bar, more preferably greater than 80 bar, even more preferred greater than 100 bar, even more preferred greater than 120 bar, very particularly preferred greater than 150 bar.
2. b) admixing isocyanate
3. c) expansion of the mixture to atmospheric pressure to form a polyurethane foam

It is clarified that the process steps of this process, as described above, are not subject to a fixed chronological sequence. For example, process steps b) and c) can take place simultaneously.

It corresponds to a preferred embodiment of the present invention if in process step a) the mixture is near or supercritical between 2 and 50% by weight, preferably between 5 and 30% by weight, particularly preferably between 7 and 20% by weight Contains fluid based on the total formulation.

Furthermore, it corresponds to a preferred embodiment of the present invention if in process step a) the mixture is between 2 and 35% by weight, preferably between 5 and 30% by weight, particularly preferably between 7.5 and 25% by weight, of at least one contains the poly-OH-functional trisiloxanes according to the invention.

Furthermore, it corresponds to a preferred embodiment of the present invention if CO _{2 is used} as the near or supercritical fluid to provide the mixture. In this case, it is preferred that the mixture at temperatures above 31 ° C. and pressures above 75 bar, preferably above 80 bar, more preferably above 100 bar, even more preferably above 120 bar, very particularly preferably at pressures is provided above 150 bar.

The mixture provided in process step a) is preferably a microemulsion. As already described, microemulsions are macroscopically isotropic, microstructured systems. It is therefore preferred in the context of the present invention if the mixture provided in process step a) is likewise macroscopically homogeneous and microstructured. However, despite the presence of a microemulsion, it may coexist with incompletely solubilized excess phases, as a result of which the mixture still appears macroscopically inhomogeneous. This behavior is well known from microemulsions and e.g. in Kahlweit et al, Angewandte Chemie Int. Ed., 1985, 24, 654. The presence of a microstructure, even at high temperatures and pressures, can be e.g. by small-angle neutron scattering or dynamic light scattering, as described, for example, in Klostermann, Quantitave Characterization of Supercritical Mircoemulsions - Dissertation, 2010, University of Cologne.

It is preferred according to the invention if in process step b) the isocyanate of the mixture from process step a) is likewise under high pressure, preferably at pressures of greater than 75 bar, more preferably greater than 80 bar, even more preferably greater than 100 bar, even more preferably of greater than 120 bar, very particularly preferably greater than 150 bar. Process steps a) and b) can be carried out, for example, on a high-pressure PU foam system with CO ₂ injection. In the polyol circuit of the machine, the mixture of polyol, scCO ₂ , the poly-OH-functional trisiloxanes according to the invention and, if appropriate, other additives is first prepared, and isocyanate is then mixed in in the high-pressure mixing head of the machine. A corresponding procedure is, for example, in DE 102009053218 A1 described.

Furthermore, it corresponds to a preferred embodiment of the present invention if, in process step c), the mixture is not expanded directly to atmospheric pressure, but rather the expansion takes place in several stages. Here, the reaction mixture can, for example, first be expanded from a high-pressure mixing head into a likewise under pressure supply container, the pressure of the supply container being lower than the pressure in the mixing head. Only in a second step is the pressure of the storage container reduced to atmospheric pressure after a defined dwell time. The storage container is preferably a heated storage container.

The polyurethane foams according to the invention preferably have an average pore size of in the range from 0.05 to 50 μm, preferably in the range from 0.07 to 20 μm, particularly preferably in the range from 0.08 to 5 μm, particularly preferably in the range from 0.09 to 1 μm, very particularly preferably in Range from 0.1 - 0.5 µm. The average cell size can preferably be determined by microscopy, preferably by electron microscopy. For this purpose, a cross section of the porous polymer coating is examined with a microscope with a sufficient magnification and the size of at least 25 cells is determined. In order to obtain sufficient statistics for this evaluation method, the magnification of the microscope should be selected so that there are at least 10x10 cells in the observation field. The mean cell size is then the arithmetic mean of the diameter of the cells under consideration. This cell size determination by means of microscopy is familiar to the person skilled in the art.

Furthermore, the polyurethane foams according to the invention have a density of preferably 10-120 kg / m ³ , preferably 20-80 kg / m ³ , particularly preferably 25-60 kg / m ³ . Furthermore, the polyurethane foams according to the invention are preferably distinguished by a compression hardness (measured at 10% compression) of at least 400 kPa, preferably of at least 500 kPa, even more preferably of at least 600 kPa and very particularly preferably of at least 650 kPa. The compression hardness can be determined by squeezing a 5 x 5 x 5 cm ³ sample of the foam by 10% and measuring the force required for this. This is possible, for example, with a material testing machine from Zwick / Roell, model Z010. This method for determining the compression hardness is generally familiar to the person skilled in the art.

It is further preferred if the polyurethane foams according to the invention have a thermal conductivity of less than 20 mW m ^-1 k ^-1 , preferably less than 19 mW m ^-1 k ^-1 , more preferably less than 18 mW m ^-1 k ^-1 , even more preferably less than 17 mW m ^-1 k ^-1 , most preferably less than 16 mWm ^-1 k ^-1 . The thermal conductivity can be determined here, for example, using a LaserComp Heat Flow Meter from TA Instruments. This method for determining the thermal conductivity is generally familiar to the person skilled in the art.

The polyurethane foams according to the invention can be used, for example, as thermal insulation materials, adsorption materials, carrier materials or for the production of lightweight components.

Examples

Determination of the OH number:

Hydroxyl numbers were determined according to the DGF C-V 17 a (53) method of the German Society for Fat Science. The samples were acetylated with acetic anhydride in the presence of pyridine and the consumption of acetic anhydride was determined by titration with 0.5 N potassium hydroxide solution in ethanol against phenolphthalein.

Determination of the iodine number:

The iodine number is a measure of the content of double bonds in a molecule. To determine the iodine number, the samples were reacted with iodine monobromide and the excess of iodine monobromide was converted into iodine by adding potassium iodide. This was back-titrated with sodium thiosulfate solution.

Determination of the SiH conversion:

The SiH determination was carried out by titrating the sample with sodium butylate solution (in n-butanol). The amount of hydrogen formed by the reaction of sodium butoxide with free SiH groups was determined by gas volumetry and used directly to calculate the SiH conversion.

Example 1: Synthesis of a di-OH-functional trisiloxane with branched polyether

218.1 g of glycerol monoallyl ether were placed in a 5 L autoclave. 4.5 g of sodium methoxide were added and the reactor contents were rendered inert by means of repeated evacuation and depressurization with nitrogen. The reaction mixture was then heated to 115 ° C. with stirring. A total of 992.1 g of ethylene oxide were metered in over the course of 1 hour at an internal temperature of 115 ° C. and an internal pressure of 1 to 2 bar (absolute) with cooling. After a reaction time of 60 minutes at 115 ° C., volatile constituents were removed by distillation in vacuo at 95 ° C., the product was neutralized with phosphoric acid and discharged from the reactor via a filter. The OH number was 150.3 mg KOH / g, the acid number 0.1 mg KOH / g. According to GPC analysis, the product has a weight-average molar mass Mw of 763 g / mol and a polydispersity Mw / Mn of 1.08.

511 g of this polyether were placed in a 1 L three-necked flask with KPG stirrer, reflux condenser and dropping funnel and heated to 50.degree. 0.5 mL of a Karstedt catalyst solution in isopropanol (w (Pt) = 1%) was added and then 1,1,1,3,5,5,5-heptamethyltrisiloxane (HMTS) was metered in over an hour. An exothermic reaction started when the siloxane was metered in. The reaction mixture was brought to 90 ° C and stirred for three hours. The conversion of SiH functions was then checked by gas volumetry. This was 100% at the end of the reaction.

Example 2: Synthesis of a di-OH-functional trisiloxane with linear polyether

396.6 g of 1,2-isopropylidene glycerol were placed in a 5 L autoclave. 8.1 g of sodium methoxide were added. The reactor was evacuated to an internal pressure of 30 mbar in order to remove any volatile constituents by distillation and inertized with nitrogen. The reaction mixture was then heated to 115 ° C. with stirring. A total of 1083.6 g of a homogeneous reaction mixture of 900.9 g of ethylene oxide and 182.7 g of propylene oxide were metered in over the course of 2 hours at an internal temperature of 115 ° C. and an internal pressure of 1 to 2 bar (absolute) with cooling. After a reaction of 60 minutes at 115 ° C., volatile components were removed by distillation in vacuo at 95 ° C. The alkoxylation product was discharged from the reactor at room temperature through a filter. The OH number was 128.4 mg KOH / g, the acid number -5.1 mg KOH / g. According to GPC analysis, the product has a weight-average molar mass Mw of 526 g / mol and a polydispersity Mw / Mn of 1.16.

In a flask, 164.6 g of sodium methoxide were added to 785 g of the alkoxylation product after inertization by repeated evacuation and relaxation with nitrogen. Volatile components were distilled off under vacuum at 115 ° C. for 2 h. After cooling to 90 ° C., the vacuum was broken with nitrogen and 276.3 g of 3-chloro-2-methylpropene were added dropwise over a period of 1 h. The reaction mixture was heated to reflux for 4 h and then volatile constituents were again removed at 90 ° C. in vacuo. 500 ml of water were added at room temperature and the organic phase was isolated. The OH number of the reaction product was 4.0 mg KOH / g and the acid number 0.1 mg KOH / g. According to GPC analysis, the product has a weight-average molar mass Mw of 582 g / mol and a polydispersity Mw / Mn of 1.17. 600 g of the reaction product were dissolved in 30 g of water and 10 g of a dilute HCl solution were added at room temperature. After stirring for 2 h at room temperature, acetone was distilled off at 110 ° C. under vacuum. The OH number was 203.0 mg KOH / g, the acid number 0.1 mg KOH / g and the iodine number 48.2 mg KOH / g. According to GPC analysis, the product has a weight-average molar mass Mw of 580 g / mol and a polydispersity Mw / Mn of 1.17.

179 g of this polyether were placed in a 500 ml three-necked flask with KPG stirrer, reflux condenser and dropping funnel and heated to 65.degree. 1.0 mL of a Karstedt catalyst solution in isopropanol (w (Pt) = 1%) was added and then 1,1,1,3,5,5,5-heptamethyltrisiloxane (HMTS) was metered in over an hour. An exothermic reaction started when the siloxane was metered in. After metering in, the reaction mixture was brought to 105 ° C. and stirred at this temperature for six hours. The conversion of SiH functions was then checked by gas volumetry. This was 100% at the end of the reaction.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 10260815 B4 [0003]
• DE 102009053218 A1 [0004, 0038]

Non-patent literature cited

• Strey et al., Colloid and Polymer Science, 1994, 272, 1005 or Kahlweit et al, Angewandte Chemie Int. Ed., 1985, 24, 654 [0012]

Claims (15)

Poly-OH-functional trisiloxane which corresponds to the general formula (1),

where R ^{1 is} a branched or linear polyoxyalkylene radical, preferably polyoxyethylene polyoxypropylene radical, which carries at least 2 free OH groups which are reactive toward isocyanates. Poly-OH-functional trisiloxane according to Claim 1 , characterized in that the radical R ^{1 is derived} from a polyether of the general formula (2) which is reacted by hydrosilylation with 1,1,1,3,5,5,5-heptamethyltrisiloxanes to give a poly-OH-functional trisiloxane can: MM ' _a D _b T _c Formula (2) where M = R ² - (O _1/2 ) _d , preferred

M '= _1/2 OR ⁴

a = 2 to 50, preferably 2 to 25, particularly preferably 2 to 10, b = 2 to 50, preferably 2 to 25, particularly preferably 2 to 10, c = 0 to 25, preferably 0 to 10, particularly preferably 1 to 5 d = 1-3 and R ^{2 is} a monovalent linear or branched alkyl radical having 1 to 20 carbon atoms, which contains a double bond hydrosilizable with respect to hydrogen siloxanes, preferably a (meth) allyl radical, a radical based on trimethylolpropane mono (meth) allyl ether or a radical on pentaerythrityl mono (meth) allyl ether, R ^{3 is} a monovalent aliphatic or aromatic hydrocarbon radical with 1 to 20 carbon atoms or H, preferably a methyl radical or H, R ^{4 is} a monovalent aliphatic saturated or unsaturated hydrocarbon radical with 1 to 20 carbon atoms or H, is preferably H and R ^{5 are} independently the same or different monovalent aliphatic saturated or unsaturated hydrocarbon radicals having 1 to 20 carbon atoms d, methyl residues in particular being preferred, with the proviso that the polyether has at least two free OH functions which are reactive toward NCO groups. Poly-OH-functional trisiloxane according to the Claims 1 or 2nd , characterized in that the polyether of the general formula (2) is prepared by reacting (meth) allyl alcohol with alkylene oxides, preferably ethylene oxide and propylene oxide, and at least one further epoxide which carries one or more free OH groups, here glycidol or glycidol-glycidyl ether are particularly preferred. Poly-OH-functional trisiloxane according to the Claims 1 or 2nd , characterized in that the polyether of the general formula (2) is prepared starting from higher-quality, (meth) allyl-modified starting alcohols which have two or more OH functions, preferably glycerol mono (meth) allyl ether, trimethylolpropane mono (meth) allyl ether and pentaerythrityl mono (meth) allyl ethers, which are subsequently reacted with alkylene oxides, preferably ethylene oxide and propylene oxide, and optionally with further epoxides which carry an additional free OH group, preferably glycidol or glycidol-glycidyl ether. Poly-OH-functional trisiloxane according to at least one of the Claims 1 to 4th , characterized in that the polyether of the general formula (2) corresponds to the general formula (3)

where e = 0 to 50, preferably 1 to 25, particularly preferably 2 to 10 f = 0 to 50, preferably 0 to 25, particularly preferably 0 to 10 g = 0 to 50, preferably 0 to 25, particularly preferably 0 to 10 and R ^{3 is} a monovalent aliphatic or aromatic hydrocarbon radicals having 1 to 20 carbon atoms, preferably a methyl radical or H and R ^{5 are} independently the same or different monovalent aliphatic saturated or unsaturated hydrocarbon radicals having 1 to 20 carbon atoms, methyl radicals in particular being preferred. Poly-OH-functional trisiloxane according to at least one of the Claims 1 to 5 , characterized in that the polyether of the general formula (3) is prepared by alkoxylation of 2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane, preferably with ethylene oxide and propylene oxide, followed by a reaction with (meth) allyl chloride and subsequent acidic deprotection of the 2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane residue. Poly-OH-functional trisiloxane according to at least one of the Claims 1 to 5 , characterized in that the polyether of the general formula (3) is prepared by alkoxylation of (meth) allyl alcohol and subsequent reaction with one equivalent of glycidol. Poly-OH-functional trisiloxane, obtainable by hydrosilylating 1,1,1,3,5,5,5-heptamethyltrisiloxanes with at least one polyether of the general formula (6)

in which h = 0 to 50, preferably 1 to 25, particularly preferably 2 to 10 i = 0 to 50, preferably 0 to 25, particularly preferably 0 to 10 j = 0 to 50, preferably 0 to 25, particularly preferably 0 to 10 k = 1 to 10, preferably 1 to 5, particularly preferably 1 to 3, very particularly preferably 1 and R ^5, independently of one another, are the same or different monovalent aliphatic saturated or unsaturated hydrocarbon radicals having 1 to 20 carbon atoms, methyl radicals in particular being preferred. Poly-OH-functional trisiloxane according to Claim 8 , characterized in that the polyether of the general formula (6) is prepared by reacting 2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane with alkenyl oxides, preferably ethylene oxide and propylene oxide, and also allyl glycidyl ether and subsequent deprotection of the 2nd , 2-dimethyl-4-hydroxymethyl-1,3-dioxolane radical, a block-like structure of the polyether is preferred, in which the allyl glycidyl ether units are attached to the end of the polyether chain. Use of a poly-OH-functional trisiloxane according to at least one of the Claims 1 to 9 as an additive for the production of polyurethane foams. Use of a poly-OH-functional trisiloxane according to Claim 10 as an additive for the production of polyurethane foams, a near or supercritical fluid, preferably near or supercritical CO _{2, being used} as a blowing agent for producing the polyurethane foam. Use of a poly-OH-functional trisiloxane according to Claim 10 or 11 as an additive for the production of polyurethane foams which result from a polyol / supercritical fluid microemulsion, preferably from a polyol / supercritical CO ₂ microemulsion containing at least one poly-OH-functional trisiloxane. Process for the production of polyurethane foams using at least one poly-OH-functional trisiloxane according to one of the Claims 1 to 9 comprising the steps a) providing a mixture consisting of at least one polyol, at least one near or supercritical fluid, preferably supercritical CO ₂ , at least one poly-OH-functional trisiloxane, according to one of the Claims 1 to 9 , and possibly other components under increased pressure b) admixing isocyanate c) expansion of the mixture to atmospheric pressure to form a polyurethane foam. Polyurethane foams obtainable through the use of at least one poly-OH-functional trisiloxane according to the Claims 1 to 9 in the production of such polyurethane foams, preferably by a method according to Claim 13 . Use of a polyurethane foam according to Claim 14 as thermal insulation material, adsorption material, carrier material or for the production of lightweight components.