EP4363480A1

EP4363480A1 - Production of hard polyurethane or polyisocyanurate foam

Info

Publication number: EP4363480A1
Application number: EP22733413.3A
Authority: EP
Inventors: Martin Glos; Jörg DIENDORF
Original assignee: Evonik Operations GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2021-07-01
Filing date: 2022-06-13
Publication date: 2024-05-08
Also published as: WO2023274699A1; CN117677648A; CA3224475A1; KR20240027765A

Abstract

The invention relates to the production of a hard PU or PIR foam, comprising bringing at least one organic polyisocyanate having two or more isocyanate functions into contact with an isocyanate-reactive mixture which comprises at least one polyol, water and at least one emulsifier, wherein: the emulsifier comprises at least one alkoxylated aromatic alcohol; the underlying aromatic alcohol comprises at least 6 and at most 40 C atoms and at least one OH function; and a maximum of 1/5 of the C atoms of the underlying aromatic alcohol are not aromatic; and, in the underlying aromatic alcohol, at least one aromatic unit must have an OH function.

Description

Production of rigid polyurethane or polyisocyanurate foam

The present invention is in the field of polyurethanes (PU) and polyisocyanurates (PIR), in particular PU or PIR rigid foams. In particular, it relates to the production of PU or PIR rigid foams using special emulsifiers, and also to the use of the foams that have been produced therewith. In the context of the present invention, these are PU or PIR rigid foams.

In the context of the present invention, polyurethane (PU) is understood in particular to mean a product obtainable by reaction of polyisocyanates and polyols. In addition to the polyurethane, other functional groups can also be formed, such as uretdiones, carbodiimides, isocyanurates, allophanates, biurets, ureas and/or uretimines. For the purposes of the present invention, PU is therefore understood to mean both polyurethane and polyisocyanurate, polyureas and polyisocyanate reaction products containing uretdione, carbodiimide, allophanate, biuret and uretimine groups. Polyimides are not included.

In the context of the present invention, polyurethane foam (PU foam) is understood to mean, in particular, foam which is obtained as a reaction product based on polyisocyanates and polyols. In addition to the polyurethane that gives the product its name, other functional groups can also be formed, such as allophanates, biurets, ureas, carbodiimides, uretdiones, isocyanurates or uretimines.

Polyisocyanurate foam (PIR foam), in particular rigid polyisocyanurate foams, have also been known for a long time and are described in the prior art. They are usually also prepared by reacting polyisocyanates with polyols, preferably polyester-polyols and polyether-polyols, the isocyanate index preferably being 180 or greater. This forms urethane structures, which result from the reaction of isocyanates with compounds with reactive hydrogen atoms, and in addition, the reaction of the isocyanate groups with one another also forms isocyanurate structures or other structures, which result from the reaction of isocyanate groups with other groups, such as polyurethane groups.

In the context of the present invention, the focus is in particular on the composition of the polyols or isocyanate-reactive mixture to be used. One or more blowing agents are preferably added to the isocyanate-reactive mixture.

Blowing agents are either chemically reactive, such as water or formic acid, or they are physical blowing agents which, due to their boiling point, evaporate during the reaction and thus lead to or contribute to foam expansion. Physical blowing agents are hydrocarbons, halogenated hydrocarbons, etc. This is known as far as is known. The blowing agents in the isocyanate-reactive mixture are often miscible only to a limited extent, so that when the mixture is prepared, the result is not a clear component but a cloudy emulsion, which in turn also entails the problem of phase separation. This means that in many cases the blowing agent separates. Since the isocyanate-reactive mixture can often contain other components of the overall reaction mixture, in addition to the isocyanate, ie flame retardants, catalysts, any dyes, stabilizers, any cell regulators, etc., such a phase separation is particularly detrimental.

Various emulsifiers can be used to avoid this turbidity or phase separation problem. Various publications relating to the use of emulsifiers to improve the stability of the isocyanate-reactive mixture containing blowing agents are known.

US Pat. No. 6,262,136 B1 describes polyol mixtures which contain fluorine-containing blowing agents which are gaseous at atmospheric pressure. Here, phenols or alkyl phenols are used to solubilize the blowing agent in the polyol. The propellants are HFC-134, HCFC-124, HCFC-22.

In US 9290604 mixtures of alkyl ethoxylates are used as emulsifiers in a water-blown reaction mixture for the production of PU foam.

The use of alkyl ethoxylates as emulsifiers for immiscible polyols is described in WO 2018/089768, flexible foams being produced from the reaction mixtures here.

In US Pat. No. 9,290,604, ethoxylated nonylphenols are used as emulsifiers in a water-blown reaction mixture for the production of PU foam.

DE 3632915 also describes ethoxylated nonylphenols in PU formulations which contain halogenated blowing agents.

WO 2020/231603 describes the use of nonionic surfactants to improve the storage stability of polyol mixtures consisting of polyester polyols and hydrocarbons as blowing agents. The surfactants are alkyl ethoxylates or block copolymers based on different alkylene oxides.

US Pat. No. 4,595,711 describes the use of nonylphenol alkoxylates in order to facilitate the use of halogenated blowing agents or to improve their solubility/emulsifiability in the polyol mixture. The object of the present invention was to make it possible to provide isocyanate-reactive mixtures with improved storage stability and to use them for the production of rigid polyurethane or polyisocyanurate foams.

Surprisingly, it has now been found that the use of alkoxylates based on certain aromatic alcohols, such as phenols or naphthols, makes it possible to solve this problem.

The object of the invention, which solves the above problem, is a method for producing a PU or PIR rigid foam, comprising bringing at least one isocyanate into contact with an isocyanate-reactive mixture which contains at least one polyol, water and at least one Emulsifier comprises, wherein one or more organic polyisocyanates having two or more isocyanate functions are used as isocyanates, characterized in that the emulsifier comprises at least one alkoxylated aromatic alcohol, wherein the underlying aromatic alcohol has at least 6 and a maximum of 40 carbon atoms and at least has an OH function, and with a maximum of 1/5 of the C atoms of the underlying aromatic alcohol being non-aromatic, and with at least one aromatic unit in the underlying aromatic alcohol having to carry an OH function.

The emulsifiers according to the invention are therefore alkoxylates of certain aromatic alcohols. By "parent aromatic alcohol" is meant that upon alkoxylation, it gives rise to the "alkoxylated aromatic alcohol".

According to a preferred embodiment of the invention, the aromatic alcohol is ethoxylated.

A suitable usable structure of the alkoxylated aromatic alcohol is based on phenol as the starting alcohol (= underlying aromatic alcohol) and has the following structure: formula 1

Here, R ¹ is hydrogen, methyl, ethyl or phenyl. It is therefore possible with preference to use ethylene oxide, propylene oxide, butylene oxide or styrene oxide for the alkoxylation n is a number from 2 to 200, preferably from 3 to 150, particularly preferably from 4 to 100.

In a further preferred embodiment of the invention, ethoxylates of aromatic alcohols are used. Shown here on phenol: Formula 2 The basic starting alcohols are based on aromatic alcohols, such as benzene with one or more OH functions: preferably phenol, pyrocatechol or resorcinol: such as B. polynuclear aromatic systems with OH functions: preferably 1-napthol or 2-naptol such as linked aromatic systems: preferably cumylphenol, biphenol, bisphenol A or bisphenol F with R ² = methyl or hydrogen, or such as styrenated phenols: preferably mono-, di- or tri-styrylphenol Examples are shown here: 2,4,6-tris(1-phenylethyl)phenol, 2,4-bis(1 -phenylethyl)phenol and p-(1-phenylethyl)phenol, it being also possible to use other isomers which are formed in the reaction of styrene with phenol.

At least one aromatic unit in the underlying aromatic alcohol must carry an OH function. The underlying aromatic alcohol can contain 6 to 40 carbon atoms. It can also contain conjugated (polynuclear) aromatic systems (naphthalene) or several aromatic systems can be linked together (bisphenols), with a maximum of 1/5 of the carbon atoms of the underlying aromatic alcohol being non-aromatic.

The numerical ratio of the carbon atoms in the starting alcohols is to be explained here as an example: In the structural formula of tristyryphenol shown above, there are a total of 30 carbon atoms, of which 6 are non-aromatic and 24 are aromatic. This means that 1/5 of the carbon atoms are not aromatic.

The maximum number of C - atoms in the underlying aromatic alcohol is 40, preferably 35, more preferably 30.

The underlying aromatic alcohol preferably contains more than 6 carbon atoms, particularly preferably more than 8.

Alkoxylates of mono-alcohols such as tristyrylphenols, naphthols or phenols are preferred. Alkoxylates of naphthols are particularly preferred. The proportion of ethylene oxide in the polyether chain is preferably greater than 80% or greater than 90%, based on the total alkylene oxide. Pure ethoxylates are particularly preferred.

It corresponds to a preferred embodiment of the invention when the alkoxylated aromatic alcohols are based on (i) mononuclear aromatic alcohols with one or more OH functions, preferably phenol, catechol or resorcinol,

(ii) polynuclear aromatic systems with one or more OH functions, preferably 1-napthol or 2-naptol,

(iii) linked aromatic systems with one or more OH functions, preferably biphenol, bisphenol A, bisphenol F or cumylphenol and/or

(iv) styrenated phenols, preferably 2,4,6-tris(1-phenylethyl)phenol, 2,4-bis(1-phenylethyl)phenol or p-(1-phenylethyl)phenol.

It corresponds to a further preferred embodiment of the invention if the alkoxylated aromatic alcohol used has 4 to 100 alkoxy groups per molecule.

It corresponds to a preferred embodiment of the invention if the alkoxylated aromatic alcohol used has a calculated HLB value greater than 10, particularly greater than 12, in particular greater than 14. A suitable upper limit is 20.

HLB values and their calculation are known per se: emulsifiers usually consist of a combination of hydrophilic and lipophilic structural elements. For example, in the case of alcohol ethoxylates, the hydroxy-terminated polyether part can be viewed as a hydrophilic structural element and the starting alcohol as a lipophilic structural element. Depending on the molar mass proportions of the respective structural elements, this results in the so-called hydrophilic-lipophilic balance, also known as the HLB value. This can then be calculated using the following formula:

Weight % of the hydrophilic structural element HLB - -

HLB values usually range from 1 to 20. The higher the proportion of hydrophilic structural elements, the higher the HLB value. This means that different emulsifiers can be compared with one another.

This method works very well for ethoxylates by dividing the respective weight percentage of ethylene oxide units by 5. For example, ethoxylates based on fatty alcohols, nonylphenols and also the alcohol ethoxylates according to the invention can be compared with one another according to their HLB value.

Mixtures of the emulsifiers according to the invention can also be used. It corresponds to a preferred embodiment of the invention if at least 2 alkoxylated aromatic alcohols are used, preferably comprising ethoxylated phenol(s) and ethoxylated naphthol(s). If the isocyanate-reactive mixture contains 2 to 30% by mass of water and 1 to 30% by mass of emulsifier and, if any, then less than 3% by mass of nonylphenol ethoxylate, a further preferred embodiment of the invention is present. These percentages by mass relate to the total of all components used that are not organic polyisocyanates. Another preferred embodiment of the invention is also present when the isocyanate-reactive mixture comprises flame retardants.

Another preferred embodiment of the invention is also present when the isocyanate-reactive mixture comprises at least one catalyst.

It also corresponds to a preferred embodiment of the invention if the emulsifiers according to the invention are added to the reaction mixture in a carrier medium or solvent.

The emulsifier according to the invention can therefore preferably be used as an emulsifier-containing preparation. An emulsifier-containing preparation can therefore also contain carrier media or solvents. These include in particular glycols, other alkoxylates and/or oils of synthetic and/or natural origin. The emulsifier-containing preparation can preferably also contain up to 15% water. "Other alkoxylates" means that these alkoxylates do not fall under the definition of the alkoxylated aromatic alcohols according to the invention.

In principle, all substances suitable as solvents can be used as carrier media. For example, glycols, other alkoxylates and/or oils of synthetic and/or natural origin are preferably used. Protic or aprotic solvents can be used. The emulsifier-containing preparations according to the invention can also be used as part of compositions with various carrier media.

Another subject of the invention is an emulsifier-containing preparation, comprising

(a) at least one, preferably at least 2, alkoxylated aromatic alcohols according to the invention, as defined above, in amounts of 20 to <100% by weight, preferably 25 to 95% by weight, particularly preferably 30 to 90% by weight,

(b) water in amounts of 0 to 30% by weight, preferably 1 to 20% by weight, particularly preferably 2 to 10% by weight,

(c) carrier media, in amounts of 0 to 80% by weight, preferably 5 to 75% by weight, particularly preferably 10 to 70% by weight, with the proviso that the sum of (b) and (c) > 0 wt% is.

Another object of the invention is a composition comprising an isocyanate-reactive mixture which at least one polyol, water and at least one, preferably at least 2 alkoxylated aromatic alcohols according to the invention, as defined above, wherein the isocyanate-reactive mixture contains 2 to 30% by mass of water and 1 to 30% by mass of emulsifier and, if any, then less than 3% by mass of nonylphenol ethoxylates, and optionally , preferably mandatory, contains flame retardants. These percentages by mass relate to the total of all components used that are not organic polyisocyanates.

Another object of the invention is a composition for the production of polyurethane or polyisocyanurate rigid foam, comprising an isocyanate component and an isocyanate-reactive mixture, optionally a foam stabilizer, a blowing agent, a catalyst, wherein the composition has at least one emulsifier, which preferably improves the storage stability of the Improved isocyanate-reactive mixture contains, wherein the emulsifier comprises at least one alkoxylated aromatic alcohol, wherein the underlying aromatic alcohol has at least 6 and a maximum of 40 carbon atoms and at least one OH function, and wherein a maximum of 1/5 of the carbon atoms of the underlying aromatic alcohol are not aromatic.

With the solution according to the invention, PU or PIR rigid foam-based products such as, for example, building insulation can be produced with a particularly high quality and the processes for producing the PU or PIR rigid foams can be made more efficient.

Preferred applications are predominantly spray foam, which can be open-cell or closed-cell, preferably open-cell, depending on the application.

The emulsification of water is an important task here, particularly in the case of open-cell spray foam, since large amounts of water are usually used as the blowing agent.

It corresponds to a preferred embodiment of the invention if the total mass fraction of emulsifiers according to the invention in the finished polyurethane foam is from 0.05 to 20% by weight, preferably from 0.1 to 15% by weight.

It corresponds to a preferred embodiment of the invention if the composition according to the invention comprises water and/or blowing agent, optionally at least one flame retardant and/or further additives which can be used advantageously in the production of rigid polyurethane or polyisocyanurate foam.

A particularly preferred composition according to the invention contains the following components: a) isocyanate-reactive compounds, in particular polyols, b) at least one polyisocyanate and/or polyisocyanate prepolymer, c) at least one, preferably 2, emulsifiers according to the invention as described above d) catalysts, e) (optional) a foam-stabilizing component on siloxanes or other surfactants, f) one or more blowing agents, g) other (optional) additives such as flame retardants, fillers, etc.

Components a), c), d), e), f) and g) can form the constituents of the isocyanate-reactive mixture, which comprises at least one emulsifier according to the invention, as defined above. Another subject of the invention is the use of emulsifiers according to the invention and/or emulsifier-containing preparations, in particular using a composition according to the invention as described above, as an emulsifier for the isocyanate-reactive mixture in the production of rigid polyurethane or polyisocyanurate foams, preferably to improve the storage stability of the isocyanate-reactive mixture and, as a result, its performance properties for the production of rigid polyurethane or polyisocyanurate foams.

Another subject of the invention is the use of one, preferably at least 2, alkoxylated aromatic alcohols, as defined above, as emulsifiers to improve the storage stability of isocyanate-reactive mixtures comprising polyols, water and optionally flame retardants.

Another object of the invention is a polyurethane or polyisocyanurate rigid foam produced by the process according to the invention. It is preferably an open-cell, water-blown spray foam.

Individual components that can be used (designated here as a) to g)) that can be used within the scope of the invention are described in more detail below. Component c), emulsifiers according to the invention, has already been described in detail. Polyols are particularly suitable as isocyanate-reactive compounds a). Suitable polyols for the purposes of the present invention are all organic substances having two or more isocyanate-reactive groups, preferably OH groups, and preparations thereof. Preferred polyols are all for the production of polyurethane systems, in particular polyurethane coatings, polyurethane elastomers or also foams; commonly used polyether polyols and/or polyester polyols and/or hydroxyl group-containing aliphatic polycarbonates, in particular polyether polycarbonate polyols and/or polyols of natural origin, so-called “natural oil-based polyols” (NOPs). The polyols usually have a functionality of preferably 1.8 to 8 and number-average molecular weights preferably in the range from 500 to 15,000. Usually the polyols with OH numbers preferably in the range from 10 to 1200 mg KOH/g are used.

Polyether polyols, for example, can be used. These can be prepared by known methods, for example by anionic polymerization of alkylene oxides in the presence of alkali metal hydroxides, alkali metal alcoholates or amines as catalysts and with the addition of at least one starter molecule that preferably contains 2 or 3 reactive hydrogen atoms or by cationic polymerization of alkylene oxides in the presence of Lewis -Acids such as antimony pentachloride or boron trifluoride etherate or by double metal cyanide catalysis. Suitable alkylene oxides contain 2 to 4 carbon atoms in the alkylene radical. Examples are tetrahydrofuran, 1,3-propylene oxide, 1,2- or 2,3-butylene oxide; ethylene oxide and 1,2-propylene oxide are preferably used. The alkylene oxides can be used individually, cumulatively, in blocks, alternately one after the other, or as mixtures. In particular, compounds with at least 2, preferably 2 to 8, hydroxyl groups or with at least two primary amino groups in the molecule are used as starter molecules. Examples of starter molecules that can be used are water, di-, tri- or tetrahydric alcohols such as ethylene glycol, 1,2- and 1,3-propanediol, diethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, castor oil, etc., higher polyfunctional polyols, in particular Sugar compounds such as glucose, sorbitol, mannitol and sucrose, polyhydric phenols, resols such as oligomeric condensation products of phenol and formaldehyde and Mannich condensates of phenols, formaldehyde and dialkanolamines and melamine, or amines such as aniline, EDA, TDA, MDA and PMDA, particularly preferably TDA and PMDA. The selection of the suitable starter molecule depends on the respective field of application of the resulting polyether polyol in the production of polyurethane

Polyester polyols, for example, can be used. These are based on esters of polybasic aliphatic or aromatic carboxylic acids, preferably with 2 to 12 carbon atoms. Examples of aliphatic carboxylic acids are succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedioic acid, maleic acid and fumaric acid. Examples of aromatic carboxylic acids are phthalic acid, isophthalic acid, terephthalic acid and the isomeric naphthalenedicarboxylic acids. The polyester polyols are obtained by condensing these polybasic carboxylic acids with polyhydric alcohols, preferably diols or triols having 2 to 12, particularly preferably 2 to 6, carbon atoms, preferably trimethylolpropane and glycerol.

For example, polyether polycarbonate polyols can be used. These are polyols containing carbon dioxide bound as a carbonate. Since carbon dioxide is used in many chemical processes Industrially produced in large quantities as a by-product, the use of carbon dioxide as a comonomer in alkylene oxide polymerizations is of particular interest from a commercial point of view. Partial replacement of alkylene oxides in polyols with carbon dioxide has the potential to significantly reduce the cost of polyol production. In addition, the use of CO2 as a comonomer is ecologically very advantageous, since this reaction represents the conversion of a greenhouse gas into a polymer. The production of polyether polycarbonate polyols by addition of alkylene oxides and carbon dioxide onto H-functional starter substances using catalysts has been known for a long time. Various catalyst systems can be used here: the first generation represented heterogeneous zinc or aluminum salts, as described, for example, in US Pat. No. 3,900,424 or US Pat. No. 3,953,383. Furthermore, mono- and binuclear metal complexes have been used successfully for the copolymerization of CO 2 and alkylene oxides (WO 2010/028362, WO 2009/130470, WO 2013/022932 or WO 2011/163133). The most important class of catalyst systems for the copolymerization of carbon dioxide and alkylene oxides are the double metal cyanide catalysts, also known as DMC catalysts (US Pat. No. 4,500,704, WO 2008/058913). Suitable alkylene oxides and H-functional starter substances are those which are also used for the preparation of carbonate-free polyether polyols, as described above.

For example, polyols based on renewable raw materials “natural oil-based polyols” (NOPs) can be used. NOPs for the production of polyurethane foams are of increasing interest in view of the limited long-term availability of fossil resources, namely oil, coal and gas, and against the background of rising crude oil prices and have already been described many times in such applications (WO 2005/033167; US 2006/0293400, WO 2006/094227, WO 2004/096882, US 2002/0103091, WO 2006/116456 and EP 1678232). A number of these polyols from various manufacturers are now available on the market (WO2004/020497, US2006/0229375, WO2009/058367). Depending on the basic raw material (e.g. soybean oil, palm oil or castor oil) and the subsequent processing, polyols with different properties result. A distinction can essentially be made here between two groups: a) polyols based on renewable raw materials, which are modified to such an extent that they can be used 100% for the production of polyurethanes (WO2004/020497, US2006/0229375); b) Polyols based on renewable raw materials which, due to their processing and properties, can only replace the petrochemical-based polyol to a certain extent (WO2009/058367). Another class of usable polyols are, for example, the so-called packed polyols (polymer polyols). These are characterized in that they contain solid organic fillers up to a solids content of 40% or more in disperse distribution. Among others, SAN, PHD and PIPA polyols can be used. SAN polyols are highly reactive polyols containing a dispersed styrene/acrylonitrile (SAN)-based copolymer. PHD polyols are highly reactive polyols which also contain polyurea in dispersed form. PIPA polyols are highly reactive polyols containing a polyurethane in dispersed form, for example formed by the in situ reaction of an isocyanate with an alkanolamine in a conventional polyol. A preferred ratio of isocyanate and polyol, expressed as the index of the formulation, ie as the stoichiometric ratio of isocyanate groups to isocyanate-reactive groups (eg OH groups, NH groups) multiplied by 100, is in the range from 10 to 1000, preferably 40 to 700, particularly preferably 50 to 600, particularly preferably 60 to 550. An index of 100 stands for a molar ratio of the reactive groups of 1 to 1.

One or more organic polyisocyanates having two or more isocyanate functions are preferably used as isocyanates b). One or more polyols having two or more isocyanate-reactive groups are preferably used as polyols. Suitable isocyanates b) for the purposes of this invention are all isocyanates which contain at least two isocyanate groups. In general, all aliphatic, cycloaliphatic, arylaliphatic and preferably aromatic polyfunctional isocyanates known per se can be used. Isocyanates are particularly preferably used in a range from 60 to 200 mol % relative to the sum of the isocyanate-consuming components.

Examples which may be mentioned here are alkylene diisocyanates having 4 to 12 carbon atoms in the alkylene radical, such as 1,12-dodecane diisocyanate, 2-ethyltetramethylene-1,4-diisocyanate, 2-methylpentamethylene-1,5-diisocyanate, tetramethylene-1,4-diisocyanate and preferably hexamethylene - 1,6-diisocyanate (HMDI), cycloaliphatic diisocyanates, such as cyclohexane-1,3- and 1-4-diisocyanate and any mixtures of these isomers, 1-isocyanato-3,35-trimethyl-5-isocyanato-rmethylcyclohexane ( Isophorone diisocyanate or IPDI for short), 2,4- and 2,6-hexahydrotoluylene-'diisocyanate and the corresponding isomer mixtures, and preferably aromatic di- and polyisocyanates, such as 2,4- and 2,6-toluene diisocyanate (TDI) and the corresponding isomer mixtures, naphthalene diisocyanate, diethyltoluene diisocyanate, mixtures of 2,4'- and 2,2'-diphenylmethane diisocyanates (MDI) and polyphenylpolymethylene polyisocyanates (crude MDI) and mixtures of crude MDI and toluene diisocyanates (TDI). The organic di- and polyisocyanates can be used individually or in the form of their mixtures. Corresponding “oligomers” of the diisocyanates can also be used (IPDI trimer based on isocyanurate, biurete-urethdione.) It is also possible to use prepolymers based on the isocyanates mentioned above.

It is also possible to use isocyanates which have been modified by the incorporation of urethane, uretdione, isocyanurate, allophanate and other groups, so-called modified isocyanates. Particularly suitable organic polyisocyanates that can be used and are therefore particularly preferred in a preferred embodiment of the invention are various isomers of toluene diisocyanate (2,4- and 2,6-toluene diisocyanate (TDI), in pure form or as isomer mixtures of different composition), 4,4 '-Diphenylmethane diisocyanate (MDI), the so-called "crude MDI" or "polymeric MDI" (contains not only the 4,4'- but also the 2,4'- and 2,2'-isomers of MDI and higher-nuclear products) and/ or the binuclear product referred to as “pure MDI” consisting predominantly of 2,4′- and 4,4′-isomer mixtures or their prepolymers can be used. Examples of particularly suitable isocyanates are listed, for example, in EP 1712578, EP 1161474, WO 00/58383, US 2007/0072951, EP 1678232 and WO 2005/085310, to which reference is made here in its entirety.

Suitable catalysts d) for the purposes of the present invention are all compounds which are able to accelerate the reaction of isocyanates with OH functions, NH functions or other isocyanate-reactive groups and with isocyanates themselves. The usual catalysts known from the prior art can preferably be used here, including, for example, amines (cyclic, acyclic; monoamines, diamines, oligomers with one or more amino groups), ammonium compounds, organometallic compounds and metal salts, preferably those of potassium, tin, iron, zinc or bismuth. In particular, mixtures of several components can be used as catalysts.

Component e) can be, for example, Si-free surfactants or, for example, organomodified siloxanes.

The use of such substances in rigid foams is known. Within the scope of this invention, all compounds that support foam production (stabilization, cell regulation, cell opening, etc.) can be used here. These compounds are well known from the prior art.

Corresponding Siloxane, which can be used in the sense of this invention, are described in the following patent fonts: CN 103665385, CN 103657518, CN 103055759, CN 103044687, US 2008/0125503, US 2015/00570 A1, EP 0867464, EP 08674, EP 0867465 , EP 0275563. These aforementioned documents are hereby introduced as a reference and are considered part of the disclosure content of the present invention. The use of polyether-modified siloxanes is particularly preferred.

The use of blowing agents f) is optional, depending on which foaming process is used. Chemical and physical blowing agents can be used. The choice of propellant depends heavily on the type of system.

In a particularly preferred embodiment, no HFO is used as blowing agent. Corresponding compounds with suitable boiling points can be used as optional physical blowing agents. Likewise, chemical blowing agents can optionally be used, which react with NCO groups and release gases, such as water or formic acid. Examples of propellants are liquefied CO 2 , nitrogen, air, volatile liquids, for example hydrocarbons with 3, 4 or 5 carbon atoms, preferably cyclo-, iso- and n-pentane, fluorocarbons, preferably HFC 245fa, HFC 134a and HFC 365mfc, chlorofluorocarbons , preferably HCFC 141b, hydrofluoroolefins (HFO) or hydrohaloolefins such as 1234ze, 1234yf, 1233zd(E) or 1336mzz, oxygen-containing compounds such as methyl formate, acetone and dimethoxymethane, or chlorinated hydrocarbons, preferably dichloromethane and 1,2-dichloroethane.

Suitable water contents for the purposes of this invention depend on whether or not one or more blowing agents are used in addition to the water. In the case of purely water-blown foams, the values are preferably from 1 to 30 pphp; if other blowing agents are also used, the amount used is reduced to preferably 0.1 to 5 pphp.

Purely water-blown foam formulations are preferred, ie the proportions of physical blowing agents are very small or preferably non-existent. As optional additives g) it is possible to use all substances known from the prior art which are used in the production of polyurethanes, in particular polyurethane foams, such as, for example, crosslinkers and chain extenders, stabilizers against oxidative degradation (so-called antioxidants), flame retardants, Surfactants, biocides, cell-refining additives, cell openers, solid fillers, antistatic additives, nucleating agents, thickeners, dyes, pigments, color pastes, fragrances, emulsifiers, etc.

The process according to the invention for the production of PU or PIR rigid foams can be carried out by known methods, for example by hand mixing or preferably with the aid of foaming machines. If the process is carried out using foaming machines, high-pressure or low-pressure machines can be used. The process according to the invention can be carried out either batchwise or continuously.

A preferred rigid polyurethane or polyisocyanurate foam formulation for the purposes of this invention has a density of 5 to 900 kg/m 3 and preferably has the composition given in Table 1. Table 1 :

Composition of a preferred rigid polyurethane or polyisocyanurate foam formulation

For further preferred embodiments and configurations of the method according to the invention, reference is also made to the statements made above in connection with the composition according to the invention.

As already mentioned, a further object of the invention is a PU or PIR rigid foam obtainable by the process mentioned.

PU or PIR rigid foam is an established technical term. The well-known and fundamental difference between flexible foam and rigid foam is that flexible foam shows elastic behavior and the deformation is therefore reversible. Hard foam, on the other hand, is permanently deformed. In the context of the present invention, PU or PIR rigid foam is understood to mean, in particular, a foam according to DIN 7726:1982-05, which advantageously has a compressive strength according to DIN 53421:1984-06 and/or DIN EN ISO 604:2003-12 >20 kPa, preferably >80 kPa, preferably >100 kPa, more preferably >150 kPa, particularly preferably >180 kPa.

In a further preferred form, an open-cell rigid foam is produced by the process according to the invention.

The foams to be produced according to the invention have densities of preferably 3 kg/m ³ to 300 kg/m ³ , preferably 4 to 250, particularly preferably 5 to 200 kg/m ³ , in particular 7 to 150 kg/m ³ . In particular, open-cell foams can be obtained. In the context of this invention, particularly preferred open-cell PU or PIR rigid foams have densities of <25 kg/m ³ , preferably <20 kg/m ³ , particularly preferably <15 kg/m ³ , in particular <10 kg/m ³ . These low foam densities are often desired in spray foams. In the context of this invention, the determination of the closed cell content and thus the open cell content is preferably carried out according to DIN ISO 4590:2016-12 using a pycnometer.

In DIN 14315-1:2013-04, various specifications for PU foam, there PU spray foam, also called spray foam, are specified. In addition to other parameters, the foams are also classified according to their closed-cell nature.

In general, better lambda values are achieved with more closed-cell foams (CCC3 and CCC4) than with more open-cell foams (CCC1 and CCC2). While an open-cell foam can be made with low densities, a closed-cell foam requires a higher density in order for the polymer matrix to be strong enough to withstand atmospheric pressure.

Preferred PU or PIR foams for the purposes of the present invention are open-cell PU or PIR rigid foams. Open-cell PU or PIR rigid foams within the meaning of this invention advantageously have a proportion of closed cells <50%, preferably <20% and in particular <10%, with the determination of the closed-cell content within the meaning of this invention preferably according to DIN ISO 4590:2016- 12 by pycnometer. This means that these foams fall into categories CCC2 or, preferably, CCC1, as defined by DIN 14315-1:2013-04.

The PU or PIR rigid foams according to the invention can be used as or for the production of insulating materials, insulating foams, headliners, packaging foams or spray foams.

Another object of the invention is the use of the PU or PIR rigid foam as an insulating material in refrigeration technology, in refrigerated furniture, in the construction, automotive, shipbuilding and/or electronics sectors, as a spray foam.

The objects according to the invention have been described above and are described below by way of example, without the invention being limited to these exemplary embodiments. If ranges, general formulas or compound classes are given, they should not only include the corresponding ranges or groups of compounds that are explicitly mentioned, but also all sub-ranges and sub-groups of compounds that are obtained by removing individual values (ranges) or compounds can. Be in the frame If documents are cited in the present description, their content, in particular with regard to the facts in connection with which the document was cited, should fully belong to the disclosure content of the present invention. Unless otherwise stated, percentages are percentages by weight. If mean values are given, they are weight averages unless otherwise stated. If parameters are given that were determined by measurement, the measurements were carried out at a temperature of 25 °C and a pressure of 101,325 Pa, unless otherwise stated.

The present invention is described by way of example in the examples listed below, without the invention, the scope of which results from the entire description and the claims, being restricted to the embodiments mentioned in the examples.

EXAMPLES:

The following raw materials were used to produce isocyanate-reactive compositions.

Polyether polyol with a molar mass of 6000 g/mol, functionality 3, with primary OH groups.

Fyrol TCPP: Tris(2-chloroisopropyl)phosphate from ICL POLYCAT® 31 from Evonik Operations GmbH, amine catalyst POLYCAT® 140 from Evonik Operations GmbH, amine catalyst POLYCAT® 142 from Evonik Operations GmbH, amine -Catalyst

TEGOSTAB® B 8580 from Evonik Operations GmbH, foam-stabilizing Si surfactant

Emulsifiers:

The alkoxylates described here can be prepared by known methods.

Emulsifier A (not inventive)

Iso-tridecanol with 6 EO units per OH function

Emulsifier B: Naphthol-based (inventive): 2-Naphthol with 11 ethylene oxide units per OH function.

Emulsifier C (inventive):

Mixture of phenol with 4 ethylene oxide units per OH function and 2-naphthol with 11 ethylene oxide units per OH function in a ratio of 2 to 8

Emulsifier D (inventive):

Mixture of phenol with 4 ethylene oxide units per OH function, 2-naphthol with 11 ethylene oxide units per OH function and water in a ratio of 17:78:5 emulsifier E (inventive)

4-cumylphenol with 12 ethylene oxide units per OH function. Examples:

Production of isocyanate-reactive mixtures

The components described in the table (data in parts by weight) were weighed into a beaker and mixed with a plate stirrer (6 cm diameter) at 1000 rpm for 30 s. 50 ml of these mixtures were then transferred to closable graduated glass cylinders so that the mixtures can be observed and no propellant can evaporate over the storage period. If phase separation occurs, the layer thickness of the separated phase can be easily read from the scale.

The isocyanate-reactive compositions according to the invention with the emulsifiers B to E show no phase separation after storage at room temperature for 14 days.

Claims

Patent Claims:

1. A method for producing a PU or PIR rigid foam comprising bringing at least one isocyanate into contact with an isocyanate-reactive mixture which comprises at least one polyol, water and at least one emulsifier, wherein as

Isocyanates one or more organic polyisocyanates with two or more isocyanate functions are used, characterized in that the emulsifier comprises at least one alkoxylated aromatic alcohol, the underlying aromatic alcohol having at least 6 and at most 40 carbon atoms and at least one OH function , and where a maximum of 1/5 of the carbon atoms of the underlying aromatic alcohol are not aromatic, and where in the underlying aromatic alcohol at least one aromatic unit must carry an OH function.

2. The method according to claim 1, characterized in that the aromatic alcohol is ethoxylated.

3. The method according to claim 1 or 2, characterized in that the alkoxylated aromatic alcohols are based on

(i) mononuclear aromatic alcohols with one or more OH functions, preferably phenol, catechol or resorcinol,

(iii) linked aromatic systems with one or more OH functions, preferably cumylphenol, biphenol, bisphenol A or bisphenol F, and/or

4. The method according to any one of claims 1 to 3, characterized in that at least 2 alkoxylated aromatic alcohols are used, preferably comprising ethoxylated phenol (s) and ethoxylated naphthol (s).

5. The method according to any one of claims 1 to 4, characterized in that the alkoxylated aromatic alcohol used has 4 to 100 alkoxy groups per molecule.

6. The method according to any one of claims 1 to 5, characterized in that the alkoxylated aromatic alcohol used has a calculated HLB value between 10 and 20, preferably an HLB value greater than 10, preferably greater than 12, in particular greater than 14.

7. The method according to any one of claims 1 to 6, characterized in that the isocyanate-reactive mixture contains 2 to 30% by mass of water and 1 to 30% by mass of emulsifier and, if any, then less than 3% by mass of nonylphenol ethoxylate.

8. The method according to any one of claims 1 to 7, characterized in that the isocyanate-reactive mixture comprises flame retardants.

9. The method according to any one of claims 1 to 8, characterized in that the isocyanate-reactive mixture comprises at least one catalyst.

10. A composition comprising an isocyanate-reactive mixture which comprises at least one polyol, water and at least one, preferably at least 2, alkoxylated aromatic alcohols as defined in any one of claims 1 to 6, the isocyanate-reactive mixture containing from 2 to 30 masses -% water and 1 to 30% by mass of emulsifier and, if any, then less than 3% by mass of nonylphenol ethoxylates, and optionally, preferably mandatory, contains flame retardants.

11. Emulsifier-containing preparation, comprising

(a) at least one, preferably at least 2, alkoxylated aromatic alcohols, as defined in one of claims 1 to 6, in particular claim 4, in amounts of 20 to <100% by weight, preferably 25 to 95% by weight, particularly preferably 30 to 90% by weight,

12. Use of one, preferably at least 2, alkoxylated aromatic alcohols, as defined in any one of claims 1 to 6, preferably claim 4, as emulsifiers to improve the storage stability of isocyanate-reactive mixtures comprising polyols, water and optionally flame retardants.

13. PU or PIR rigid foam, produced by a method according to any one of claims 1 to

9.

14. PU or PIR rigid foam, characterized in that it is an open-cell, water-driven spray foam.