Production of rigid polyurethane or polyisocyanurate foams

Abstract

Production of rigid polyurethane or polyisocyanurate foams 1. A method for producing a rigid PU or PIR foam comprising the steps of contacting at least one organic polyisocyanate having two or more isocyanate functional groups with an isocyanate-reactive mixture comprising at least one polyol, water and at least one emulsifier; The emulsifier comprises at least one alkoxylated aromatic alcohol, the parent aromatic alcohol having at least 6 and at most 40 carbon atoms and at least one OH functional group, and at most ⅕ of the carbon atoms of the parent aromatic alcohol are non-aromatic; At least one aromatic unit in the parent aromatic alcohol must have an OH functionality.

Description

[Technical field]

[0001] The present invention relates to the field of polyurethane (PU) and polyisocyanurate (PIR), in particular rigid PU or PIR foams. More specifically, the present invention relates to the preparation of rigid PU or PIR foams using specific emulsifiers, and further to the use of the foams prepared therefrom. The present invention relates to rigid PU or PIR foams. [Background technology]

[0002] Polyurethane (PU) in the context of this specification is understood to mean in particular the product obtained by the reaction of polyisocyanate with polyol. In addition to polyurethane, further functional groups such as uretdione, carbodiimide, isocyanurate, allophanate, biuret, urea and / or uretonimine may also be generated in the reaction. Thus, PU is understood for the purposes of the present invention to mean not only polyurethane, but also polyisocyanate reaction products containing uretdione, carbodiimide, allophanate, biuret and uretonimine groups. Polyimides are not included.

[0003] In the context of this specification, polyurethane foams (PU foams) are understood to mean in particular foams obtained as reaction products based on polyisocyanates and polyols. In addition to the polyurethanes of the same name, further functional groups such as allophanates, biurets, ureas, carbodiimides, uretdiones, isocyanurates or uretonimines may be produced as well.

[0004] Polyisocyanurate foams (PIR foams), in particular rigid polyisocyanurate foams, have likewise been known for a long time and are described in the prior art. They are likewise typically produced by reaction of polyisocyanates with polyols, preferably polyester polyols and polyether polyols, with an isocyanate index preferably of 180 or more. In this process, urethane structures are formed as a result of the reaction of isocyanates with compounds having reactive hydrogen atoms. In turn, further isocyanurate structures are formed by reaction of the isocyanate groups with each other, or further structures resulting from the reaction of isocyanate groups with other groups, for example polyurethane groups.

[0005] The invention relates more particularly to the composition of the polyol or isocyanate-reactive mixture to be used.It is preferred that one or more blowing agents are added to the isocyanate-reactive mixture.

[0006] The blowing agent may be chemically reactive, such as water or formic acid, or it may be a physical blowing agent that, due to its boiling point, evaporates during the reaction, resulting in or promoting foaming. Physical blowing agents are hydrocarbons, halogenated hydrocarbons, etc. This is known.

[0007] In many cases, the blowing agent is only miscible to a limited extent in the isocyanate-reactive mixture, so that when the mixture is produced, a transparent component is not obtained, but instead a cloudy emulsion is obtained, which in turn is accompanied by the problem of phase separation. That is, in many cases, the blowing agent separates. Such phase separation is particularly harmful, since the isocyanate-reactive mixture often contains, in addition to the isocyanate, further components of the overall reaction mixture, namely flame retardants, catalysts, possibly dyes, stabilizers, possibly cell regulators, etc.

[0008] To avoid this problem of turbidity and phase separation, various emulsifiers can be used. Various publications are known regarding the use of emulsifiers to improve the stability of isocyanate reactive mixtures containing blowing agents.

[0009] US Patent No. 6,262,136 describes a polyol mixture containing a fluorine-containing blowing agent that is gaseous at standard pressure. In this document, phenol or alkylphenol is used to solubilize the blowing agent in the polyol. The blowing agent is HFC134, HCFC-124, or HCFC-22.

[0010] US Pat. No. 9,290,604 uses a mixture of alkyl ethoxylates as emulsifiers in a water-blown reaction mixture for producing PU foams.

[0011] The use of alkyl ethoxylates as emulsifiers for immiscible polyols is described in WO 2018 / 089768 to produce flexible foams from the reaction mixture.

[0012] In US Pat. No. 9,290,604, ethoxylated nonylphenol is used as an emulsifier in a water-blown reaction mixture for producing PU foam.

[0013] Ethoxylated nonylphenols are also described in German Patent No. 3632915 as PU formulations containing halogenated blowing agents.

[0014] WO 2020 / 231603 describes the use of non-ionic surfactants to improve the storage stability of polyol mixtures containing polyester polyols and hydrocarbons as blowing agents, the surfactants being alkyl ethoxylates or block copolymers based on various alkylene oxides.

[0015] U.S. Pat. No. 4,595,711 describes the use of nonylphenol alkoxylates to facilitate the use of halogenated blowing agents or to improve the solubility / emulsification of halogenated blowing agents in polyol mixtures. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] U.S. Patent No. 6,262,136 [Patent Document 2] U.S. Patent No. 9,290,604 [Patent Document 3] International Publication No. 2018 / 089768 Brochure [Patent Document 4] German Patent No. 3632915 [Patent Document 5] U.S. Pat. No. 4,595,711 Summary of the Invention [Problem to be solved by the invention]

[0017] It was an object of the present invention to provide isocyanate-reactive mixtures with improved storage stability so that these can be used in the production of rigid polyurethane or polyisocyanurate foams. [Means for solving the problem]

[0018] It has surprisingly been found that the use of alkoxylates based on certain aromatic alcohols, such as for example phenol or naphthol, makes it possible to achieve this object.

[0019] The subject of the present invention, which achieves the above-mentioned objectives, is a process for the preparation of rigid PU or PIR foams, comprising the step of contacting at least one isocyanate with an isocyanate-reactive mixture comprising at least one polyol, water and at least one emulsifier, As the isocyanate, one or more organic polyisocyanates having two or more isocyanate functional groups are used, The emulsifier comprises at least one alkoxylated aromatic alcohol, the parent aromatic alcohol having at least 6 and at most 40 carbon atoms and at least one OH functional group, and at most 1 / 5 of the carbon atoms of the parent aromatic alcohol are non-aromatic; At least one aromatic unit in the parent aromatic alcohol must have an OH functionality.

[0020] Thus, the emulsifier according to the present invention is an alkoxylate of a particular aromatic alcohol. By "parent aromatic alcohol" is meant the particular aromatic alcohol that becomes the "alkoxylated aromatic alcohol" after it has been alkoxylated.

[0021] According to a preferred embodiment of the present invention, the aromatic alcohol is ethoxylated.

[0022] A suitable and useful structure of an alkoxylated aromatic alcohol is based on phenol as the starting alcohol (=parent aromatic alcohol) and has the following structure:

[0023] [ka]

[0024] In the formula, R 1 is hydrogen, methyl, ethyl or phenyl. Thus, ethylene oxide, propylene oxide, butylene oxide or styrene oxide may preferably be used for the alkoxylation. n is a number from 2 to 200, preferably from 3 to 150, and particularly preferably from 4 to 100.

[0025] In a further preferred embodiment of the invention, ethoxylates of aromatic alcohols are used, which are illustrated using phenol.

[0026] [ka]

[0027] The parent starting alcohol is For example, benzene, preferably phenol, pyrocatechol or resorcinol, etc., having one or more OH functional groups;

[0028] [ka]

[0029] For example, polycyclic aromatic systems carrying OH functions, such as preferably 1-naphthol or 2-naphthol;

[0030] [ka]

[0031] For example, a bound aromatic system, preferably cumylphenol, biphenol, bisphenol A or bisphenol F; or

[0032] [ka]

[0033] (In the formula, R 2 is methyl or hydrogen.) For example, styrenated phenols, preferably mono-, di- or tristyrylphenols. It is based on aromatic alcohols. Examples included herein are 2,4,6-tris(1-phenylethyl)phenol, 2,4-bis(1-phenylethyl)phenol and p-(1-phenylethyl)phenol.

[0034] [ka]

[0035] Additional isomers resulting from the reaction of styrene with phenol may also be used.

[0036] At least one aromatic unit in the parent aromatic alcohol must have an OH functionality. The parent aromatic alcohol may have from 6 to 40 carbon atoms. In this case, conjugated (polycyclic) aromatic systems may be present (naphthalenes) or two or more aromatic systems may be bonded to each other (bisphenols), and at most 1 / 5 of the carbon atoms of the parent aromatic alcohol are not aromatic. Take the ratio of the number of carbon atoms in the starting alcohol as an example. In the structural formula of tristyrylphenol shown above, there are a total of 30 carbon atoms, of which 6 carbon atoms are not aromatic and 24 carbon atoms are aromatic. This shows that 1 / 5 of the carbon atoms are not aromatic.

[0037] The maximum number of carbon atoms in the parent aromatic alcohol is 40, preferably 35, and more preferably 30.

[0038] Preferably, there are more than 6 carbon atoms in the parent aromatic alcohol, and more preferably there are more than 8 carbon atoms.

[0039] Alkoxylates of monoalcohols such as tristyrylphenol, naphthol or phenol are preferred, with naphthol alkoxylates being especially preferred.

[0040] The proportion of ethylene oxide in the polyether chains is preferably more than 80% or even more than 90%, based on the total alkylene oxide. Pure ethoxylates are particularly preferred.

[0041] In a preferred embodiment of the present invention, the alkoxylated aromatic alcohol is (i) a monocyclic aromatic alcohol having one or more OH functional groups, preferably phenol, pyrocatechol or resorcinol; (ii) polycyclic aromatic systems having one or more OH functions, preferably 1-naphthol or 2-naphthol, (iii) bound aromatic systems having 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 is based on.

[0042] In a further preferred embodiment of the present invention, the alkoxylated aromatic alcohol used has from 4 to 100 alkoxy groups per molecule.

[0043] In a preferred embodiment of the invention, the alkoxylated aromatic alcohols used have a calculated HLB value of more than 10, in particular more than 12, in particular more than 14. A suitable upper limit is 20.

[0044] The HLB value and its calculation itself are already known. Emulsifiers are usually composed of a combination of hydrophilic and lipophilic components. Thus, for example, in alcohol ethoxylates, the hydroxy-terminated polyether moiety can be considered as the hydrophilic component and the starting alcohol as the lipophilic component. The "hydrophilic-lipophilic balance", also called the HLB value, comes from the molar mass ratio of each component. It can be calculated according to the following formula:

[0045]

number

[0046] HLB values ​​generally range from 1 to 20. The higher the proportion of hydrophilic components, the higher the HLB value. Thus, different emulsifiers can be compared to each other. This method can be very easily used for ethoxylates by dividing the respective weight proportions of ethylene oxide units by 5. Thus, for example, ethoxylates based on aliphatic alcohols, nonylphenol and the alcohol ethoxylates according to the invention can be compared with each other according to their HLB values.

[0047] It is also possible to use a mixture of emulsifiers according to the invention. In a preferred embodiment of the present invention, at least two alkoxylated aromatic alcohols are used, preferably at least two alkoxylated aromatic alcohols containing an ethoxylated phenol and an ethoxylated naphthol.

[0048] It is a further preferred embodiment of the invention when the isocyanate-reactive mixture contains from 2% to 30% by weight of water, from 1% to 30% by weight of emulsifier, and less than 3% by weight of nonylphenol ethoxylate, if any. These weight percentages are based on the sum of all components used other than the organic polyisocyanate. It is a further preferred embodiment of the invention where the isocyanate-reactive mixture contains a flame retardant.

[0049] It is a further preferred embodiment of the invention where the isocyanate-reactive mixture comprises at least one catalyst.

[0050] It is likewise a preferred embodiment of the invention if the emulsifier according to the invention is added to the reaction mixture in a carrier medium or solvent.

[0051] Therefore, the emulsifier according to the invention can preferably be used as an emulsifier-containing formulation. Thus, the emulsifier-containing formulation may also contain carrier media or solvents. These include, in particular, glycols, other alkoxylates and / or oils of synthetic and / or natural origin. Up to 15% water may also be present in the emulsifier-containing formulation. By "other alkoxylates" it is meant that these alkoxylates are not included in the definition of alkoxylated aromatic alcohols according to the invention.

[0052] In principle, the carrier medium used can be any substance suitable as a solvent. Preferred examples include glycols, other alkoxylates and / or oils of synthetic and / or natural origin. Protic or aprotic solvents can be used. The emulsifier-containing formulation according to the present invention can also be used as part of a composition with a different carrier medium.

[0053] The present invention further comprises: (a) from 20% to less than 100% by weight, preferably from 25% to 95% by weight, particularly preferably from 30% to 90% by weight, of at least one, preferably at least two, alkoxylated aromatic alcohols according to the invention and as defined above, (b) 0% to 30% by weight, preferably 1% to 20% by weight, particularly preferably 2% to 10% by weight, of water; (c) 0% to 80% by weight, preferably 5% to 75% by weight, particularly preferably 10% to 70% by weight of a carrier medium Including, The emulsifier-containing formulation has a sum of (b) and (c) greater than 0% by weight.

[0054] The present invention further provides a composition comprising an isocyanate-reactive mixture comprising at least one polyol, water and at least one, preferably at least two, alkoxylated aromatic alcohols according to the invention and as defined above, the isocyanate-reactive mixture comprising 2% to 30% by weight of water, 1% to 30% by weight of an emulsifier, less than 3% by weight of nonylphenol ethoxylate, if any, and optionally, preferably essentially a flame retardant. These weight percentages are based on the sum of all components used other than the organic polyisocyanate.

[0055] The present invention further provides a composition for producing rigid polyurethane or polyisocyanurate foams comprising an isocyanate component, an isocyanate-reactive mixture, and optionally a foam stabilizer, a blowing agent, and a catalyst, the composition including at least one emulsifier that preferably improves the storage stability of the isocyanate-reactive mixture, the emulsifier including at least one alkoxylated aromatic alcohol, the parent aromatic alcohol having at least 6 and at most 40 carbon atoms and at least one OH functional group, and at most ⅕ of the carbon atoms of the parent aromatic alcohol being non-aromatic.

[0056] The solution according to the invention therefore makes it possible to produce extremely high quality rigid PU or PIR foam-based products, such as building insulation, and to make the manufacturing process for rigid PU or PIR foams more efficient.

[0057] The preferred applications are primarily spray foams, which after application can be open or closed cell, preferably open cell.

[0058] Water emulsification is an important objective, especially in open cell spray foams, since large amounts of water are typically used as the blowing agent.

[0059] In a preferred embodiment of the invention, the total mass proportion of the emulsifiers according to the invention in the finished polyurethane foam is 0.05% to 20% by weight, preferably 0.1% to 15% by weight.

[0060] In a preferred embodiment of the invention, the composition according to the invention comprises water and / or a blowing agent, optionally at least one flame retardant and / or further additives which can be advantageously used for the production of rigid polyurethane or polyisocyanurate foams.

[0061] Particularly preferred compositions according to the invention comprise the following components: (a) isocyanate-reactive compounds, in particular polyols, (b) at least one polyisocyanate and / or polyisocyanate prepolymer; (c) at least one, preferably two, emulsifiers according to the invention and described above, (d) a catalyst; (Optionally) a siloxane or other surfactant-based foam stabilizing component; (f) one or more blowing agents; (g) Further (optional) additives such as flame retardants, fillers, etc.

[0062] Components (a), (c), (d), (e), (f) and (g) may form constituents of an isocyanate-reactive mixture that includes at least one emulsifier according to the present invention as described above.

[0063] The present invention further provides the use of the emulsifier according to the invention and / or the emulsifier-containing formulation as an emulsifier for an isocyanate-reactive mixture in the production of rigid polyurethane or polyisocyanurate foams, in particular with a composition according to the invention as described above, preferably for improving the storage stability of the isocyanate-reactive mixture and thus the use properties of the isocyanate-reactive mixture in the production of rigid polyurethane or polyisocyanurate foams.

[0064] The present invention further provides the use of one, preferably at least two, alkoxylated aromatic alcohols as defined above as emulsifiers for improving the storage stability of an isocyanate-reactive mixture comprising a polyol, water and optionally a flame retardant.

[0065] The present invention further provides a rigid polyurethane or polyisocyanurate foam produced by the process according to the invention, which is preferably an open-cell water-blown spray foam.

[0066] The individual possible components (considered (a) to (g)) that can be used within the context of this specification are described in more detail below: Component (c), which is the emulsifier according to the invention, has already been described in detail.

[0067] Suitable isocyanate-reactive compounds (a) are in particular polyols. Polyols suitable for the purposes of the present invention are all organic substances having two or more isocyanate-reactive groups, preferably OH groups, and also blends thereof. Preferred polyols are all polyether polyols, and / or polyester polyols, and / or hydroxyl-containing aliphatic polycarbonates, in particular polyether polycarbonate polyols, and / or polyols of natural origin, known as "natural oil-based polyols" (NOPs) and customarily used for the production of polyurethane systems, in particular polyurethane coatings, polyurethane elastomers or foams. The polyols usually have a functionality preferably between 1.8 and 8 and a number-average molecular weight preferably in the range between 500 and 15,000. It is customary to use polyols whose OH number is in the range between 10 and 1,200 mg KOH / g.

[0068] For example, polyether polyols 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 alkoxides or amines as catalysts and the addition of at least one starter molecule containing, in combined form, preferably two or three reactive hydrogen atoms, or by cationic polymerization of alkylene oxides in the presence of Lewis acids, for example 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 include tetrahydrofuran, 1,3-propylene oxide and 1,2- or 2,3-butylene oxide, with preference being given to using ethylene oxide and 1,2-propylene oxide. The alkylene oxides can be used individually, cumulatively, in blocks, alternating successively or as mixtures. The starter molecules used can in particular be compounds having at least two, preferably 2 to 8, hydroxyl groups or at least two primary amino groups in their molecules. The starter molecules used can be, for example, water, dihydric, trihydric or tetrahydric alcohols such as ethylene glycol, propane-1,2- and -1,3-diol, diethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, castor oil, higher polyfunctional polyols, in particular sugar compounds such as glucose, sorbitol, mannitol and sucrose, polyhydric phenols, resols such as oligomeric condensation products of phenol with formaldehyde and Mannich condensation products of phenol, formaldehyde and dialkanolamines, and melamine, or amines such as aniline, EDA, TDA, MDA and PMDA, more preferably TDA and PMDA. Suitable starter molecules are selected depending on the respective field of application of the resulting polyether polyol in the production of polyurethanes.

[0069] For example, polyester polyols can be used. These are based on esters of polybasic aliphatic or aromatic carboxylic acids, preferably having 2 to 12 carbon atoms. Examples of aliphatic carboxylic acids are succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic 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 condensation of these polybasic carboxylic acids with polyhydric alcohols, preferably diols or triols having 2 to 12, more preferably 2 to 6, carbon atoms, preferably trimethylolpropane and glycerol.

[0070] For example, polyether polycarbonate polyols can be used. These are polyols that contain carbon dioxide in the form of bound carbonate. The use of carbon dioxide as a comonomer in alkylene oxide polymerization is particularly interesting from a commercial point of view, since carbon dioxide is produced in large quantities as a by-product in many processes in the chemical industry. Partial replacement of alkylene oxides in polyols with carbon dioxide can clearly reduce the costs of polyol production. Furthermore, the use of CO2 as a comonomer is environmentally very desirable, since this reaction results in the conversion of greenhouse gases into the polymer. The preparation of polyether polycarbonate polyols by the addition of alkylene oxides and carbon dioxide to H-functional starting materials with the aid of catalysts has been known for a long time. Various catalyst systems can be used. The first generation was of heterogeneous zinc or aluminum salts, as described, for example, in US Pat. No. 3,900,424 or US Pat. No. 3,953,383. Furthermore, mononuclear and binuclear metal complexes have been successfully used for the copolymerization of CO2 with 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 is the class of double metal cyanide catalysts, also called DMC catalysts (US Pat. No. 4,500,704, WO 2008 / 058913). Suitable alkylene oxides and H-functional starting materials are those that are also used for the preparation of carbonate-free polyether polyols, as mentioned above.

[0071] For example, polyols based on renewable raw materials, "natural oil-based polyols" (NOPs), can be used. NOPs for polyurethane foam production are of increasing interest due to the limited long-term availability of fossil resources such as oil, coal and gas 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 1 678 232). A large number of such polyols are now available on the market from various manufacturers (WO 2004 / 020497, US 2006 / 0229375, WO 2009 / 058367). Depending on the base raw material (e.g. soybean oil, palm oil or castor oil) and the subsequent processing, polyols with different property profiles are obtained. Essentially two groups can be distinguished: (a) polyols based on renewable raw materials modified to be able to be used 100% in the production of polyurethanes (WO 2004 / 020497, US 2006 / 0229375), (b) polyols based on renewable raw materials which, due to their processing and properties, can only replace petrochemical polyols up to a certain percentage (WO 2009 / 058367).

[0072] A further group of polyols that can be used is, for example, that of "filled polyols" (polymer polyols). These are characterized by the fact that they contain dispersed solid organic fillers up to a solids content of 40% or more. Usable polyols include SAN, PUD and PIPA polyols. SAN polyols are highly reactive polyols that contain dispersed copolymers based on styrene-acrylonitrile (SAN). PUD polyols are also highly reactive polyols that contain polyureas in dispersed form. PIPA polyols are highly reactive polyols that contain dispersed polyurethanes, which are produced, for example, by in situ reaction of isocyanates with alkanolamines in conventional polyols.

[0073] Preferred ratios of isocyanate to polyol, expressed as a blend index, i.e. the stoichiometric ratio of isocyanate groups to isocyanate reactive groups (e.g. OH groups, NH groups) multiplied by 100, range from 10 to 1000, preferably 40 to 700, more preferably 50 to 600, and especially preferably 60 to 550. An index of 100 represents a molar ratio of reactive groups of 1:1.

[0074] The isocyanate (b) used is preferably one or more organic polyisocyanates having two or more isocyanate functional groups. The polyol used is preferably one or more polyols having two or more isocyanate-reactive groups.

[0075] Isocyanates (b) suitable for the purposes of the present invention are all isocyanates containing at least two isocyanate groups. In general, it is possible to use all aliphatic, cycloaliphatic, arylaliphatic, preferably aromatic polyfunctional isocyanates known per se. It is particularly preferred to use isocyanates in the range of 60 to 200 mol %, based on the total of the isocyanate consuming components.

[0076] Specific examples include alkylene diisocyanates having 4 to 12 carbon atoms in the alkylene group, such as dodecane 1,12-diisocyanate, 2-ethyltetramethylene 1,4-diisocyanate, 2-methylpentamethylene 1,5-diisocyanate, tetramethylene 1,4-diisocyanate, preferably hexamethylene 1,6-diisocyanate (HMDI), alicyclic diisocyanates such as cyclohexane 1,3- and 1,4-diisocyanate and all mixtures of these isomers, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophosphatidyl cyclohexane), and the like. The preferred isocyanates are toluene 2,4- and 2,6-diisocyanate (TDI) and the corresponding isomer mixtures, preferably aromatic diisocyanates and polyisocyanates, such as toluene 2,4- and 2,6-diisocyanate (TDI) and the corresponding isomer mixtures, naphthalene diisocyanate, diethyltoluene diisocyanate, mixtures of diphenylmethane 2,4'- and 2,2'-diisocyanate (MDI) and polyphenylpolymethylene polyisocyanate (crude MDI), mixtures of crude MDI and toluene diisocyanate (TDI). The organic diisocyanates and polyisocyanates can be used individually or in the form of their mixtures. It is also possible to use the corresponding "oligomers" of diisocyanates (IPDI trimers based on isocyanurates, biurets, uretdione). In addition, the use of prepolymers based on the abovementioned isocyanates is also possible.

[0077] It is also possible to use isocyanates which have been modified by the incorporation of urethane, uretdione, isocyanurate, allophanate and other groups, referred to as modified isocyanates.

[0078] Usable organic polyisocyanates which are particularly suitable and therefore may be particularly preferably used in the context of preferred embodiments of the present invention are the various isomers of toluene diisocyanate (toluene 2,4- and 2,6-diisocyanate (TDI) in pure form or as isomeric mixtures of various compositions), diphenylmethane 4,4'-diisocyanate (MDI), "crude MDI" or "polymeric MDI" (comprising the 4,4' isomer of MDI, the 2,4' and 2,2' isomers and products with more than two rings) and also the two-ring products called "pure MDI", which are mainly composed of the 2,4' and 4,4' isomer mixtures, and prepolymers derived therefrom. Examples of particularly suitable isocyanates are detailed, for example, in EP 1 712 578 A, EP 1 161 474 A, WO 00 / 58383 A, US 2007 / 0072951 A, EP 1 678 232 A and WO 2005 / 085310 A, which are incorporated herein by reference.

[0079] Suitable catalysts (d) in the context of this specification are all compounds capable of promoting the reaction of isocyanates with OH, NH or other isocyanate-reactive groups and with isocyanates themselves.It is preferable to use conventional catalysts known from the prior art, such as, for example, amines (cyclic, acyclic; monoamines, diamines, oligomers with one or more amino groups), ammonium compounds, organometallic compounds and metal salts, preferably potassium, tin, iron, zinc or bismuth metal salts.In particular, it is possible to use a mixture of more than one component as catalyst.

[0080] As component (e) it is possible to use, for example, Si-free surfactants or, for example, organomodified siloxanes.

[0081] The use of such substances in rigid foams is known. In the context of this specification, it is possible to use all compounds that aid in foam production (stabilization, cell control, cell opening, etc.). These compounds are sufficiently well known from the prior art.

[0082] Corresponding siloxanes that can be used in the context of this specification are described, for example, in the following patent specifications: CN 103665385, CN 103657518, CN 103055759, CN 103044687, US 2008 / 0125503, US 2015 / 0057384, EP 1520870, EP 1211279, EP 0867464, EP 0867465, EP 0275563. The above-mentioned documents are incorporated herein by reference and are considered to be part of the disclosure of the present invention. The use of polyether-modified siloxanes is particularly preferred.

[0083] A blowing agent (f) is optionally used depending on which foaming process is used. Chemical and physical blowing agents can be used. The choice of blowing agent is highly dependent on the nature of the system.

[0084] In particularly preferred embodiments, HFOs are not used as blowing agents.

[0085] Any physical blowing agent used can be a corresponding compound with a suitable boiling point.Similarly, it is also possible to use chemical blowing agents that react with NCO groups to release gas, such as water or formic acid.Examples of blowing agents are liquefied CO2, nitrogen, air, volatile liquids, such as hydrocarbons with 3, 4 or 5 carbon atoms, preferably cyclo-, iso- and n-pentane, hydrofluorocarbons, preferably HFC245fa, HFC134a and HFC365mfc, hydrochlorofluorocarbons, preferably HCFC141b, hydrofluoroolefins (HFOs) 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.

[0086] The water content suitable for the purposes of the present invention depends on whether one or more blowing agents are used in addition to water. For pure water foams, values ​​between 1 and 30 pphp are preferred. If other blowing agents are additionally used, the amount of water used is preferably reduced to 0.1 to 5 pphp.

[0087] Pure water foam formulations are preferred, so in this case the proportion of physical blowing agent is very low or preferably absent.

[0088] Optional additives (g) which may be used include all substances known from the prior art and used in the production of polyurethanes, in particular polyurethane foams, such as crosslinkers and chain extenders, stabilizers against oxidative degradation (known as antioxidants), flame retardants, surfactants, biocides, cell refining additives, cell opening agents, solid fillers, antistatic additives, nucleating agents, thickeners, dyes, pigments, color pastes, fragrances and emulsifiers.

[0089] The process according to the invention for producing rigid PU or PIR foams can be carried out by known methods, such as by hand mixing, or preferably by a foaming machine. When carrying out the process by means of a foaming machine, it is possible to use high-pressure or low-pressure foaming machines. The process according to the invention can be carried out batchwise or continuously.

[0090] Preferred rigid polyurethane or polyisocyanurate foam formulations in the context of this specification have a foam density of 5 to 900 kg / m 3 and preferably has the composition shown in Table 1.

[0091] [Table 1]

[0092] For further preferred embodiments and configurations of the method according to the invention, reference is also made to the details already given above in connection with the composition according to the invention.

[0093] As already mentioned, the present invention further provides a rigid PU or PIR foam obtainable by the process described.

[0094] Rigid PU or PIR foams are established terminology. The known fundamental difference between soft and rigid foams is that the former exhibit elastic properties, so that deformations are reversible. In contrast, rigid foams are permanently deformed. In the context of this specification, rigid PU or PIR foams are understood in particular to mean foams according to DIN 7726:1982-05, which advantageously have a compressive strength according to DIN 53421:1984-06 and / or DIN EN ISO 604:2003-12 of 20 kPa or more, preferably 80 kPa or more, preferably 100 kPa or more, more preferably 150 kPa or more, particularly preferably 180 kPa or more.

[0095] In a further preferred embodiment, an open-cell foam is produced by the method according to the invention.

[0096] The foam produced according to the present invention preferably has a foam density of 3 kg / m 3 ~300kg / m3, preferably 4~250kg / m 3 , particularly preferably 5 to 200 kg / m 3 , especially 7 to 150 kg / m 3 In particular, open-cell foams can be obtained. Particularly preferred open-cell rigid PU or PIR foams in the context of this specification have a density of 25 kg / m 3 Less than 20 kg / m 3 Less than 15 kg / m, particularly preferably 3 Below, especially 10kg / m 3 These low foam densities are often desired for spray foams.

[0097] In the present context, the closed cell content, and therefore the open cell content, is preferably measured by pycnometer in accordance with DIN ISO 4590:2016-12.

[0098] DIN 14315-1:2013-04 lays down various specifications for PU foams, among which sprayable PU foams (also called spray foams). Foams are classified by their closed cell content, among other parameters.

[0099] [Table 2]

[0100] In general, better lambda values ​​are obtained using relatively closed cell foams (CCC3 and CCC4) rather than relatively open cell foams (CCC1 and CCC2). Open cell foams can be made at lower densities, while closed cell foams require higher densities to ensure that the polymer matrix is ​​stable enough to withstand atmospheric pressure.

[0101] Preferred PU or PIR foams in the context of this specification are open-cell rigid PU or PIR foams. Open-cell rigid PU or PIR foams in the context of this specification advantageously have a proportion of closed cells of 50% or less, preferably 20% or less, in particular 10% or less, the closed cell content in the context of this specification being preferably measured by pycnometer in accordance with DIN ISO 4590:2016-12. This means that these foams are classified in the category CCC2 or preferably CCC1 in accordance with the specifications of DIN 14315-1:2013-04.

[0102] The rigid PU or PIR foams according to the present invention can be used as or for the production of insulation, thermal insulation foam, roof liner, packaging foam or spray foam.

[0103] The invention further provides the use of the rigid PU or PIR foams as spray foams, as thermal insulation in refrigeration technology, refrigeration equipment, the construction sector, the automotive sector, the shipbuilding sector and / or the electronics sector.

[0104] The subject matter of the present invention is described above and hereinafter by way of example, without intending the present invention to be limited to these exemplary embodiments. When ranges, general formulae or groups of compounds are described, these are intended to encompass not only the corresponding ranges or groups of compounds explicitly stated, but also all subranges and subgroups of compounds obtained by excluding the individual values ​​(ranges) or compounds. When documents are cited in the context of this specification, they are intended to form part of the disclosure of the present invention in their entirety, particularly with respect to the subject matter that constitutes the context in which they are cited. Percentages are by weight % unless otherwise stated. When average values ​​are stated, these are weight averages, unless otherwise stated. When parameters specified by measurement are stated, the measurements are carried out at a temperature of 25° C. and a pressure of 101325 Pa, unless otherwise stated.

[0105] The following examples are provided to illustrate the present invention, and are not intended to limit the present invention to the embodiments cited in the examples, and the scope of the present invention will be apparent from the entire specification and claims. EXAMPLES

[0106] An isocyanate-reactive composition was prepared using the following ingredients:

[0107] polyether polyol with a molar mass of 6000 g / mol, functionality 3 and primary OH groups -Fyrol TCPP: Tris(2-chloroisopropyl) phosphate manufactured by ICL POLYCAT® 31, an amine catalyst, from Evonik Operations GmbH POLYCAT® 140, an amine catalyst, from Evonik Operations GmbH POLYCAT® 142, an amine catalyst, from Evonik Operations GmbH TEGOSTAB® B8580, a foam-stabilizing Si surfactant from Evonik Operations GmbH

[0108] emulsifier: The alkoxylates described herein can be prepared by known methods.

[0109] Emulsifier A (non-inventive) Isotridecanol with 6 EO units per OH function

[0110] Emulsifier B: Naphthol-based (inventive) 2-Naphthol with 11 ethylene oxide units per OH function

[0111] Emulsifier C (Inventive) A 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 2:8.

[0112] Emulsifier D (Inventive) A 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.

[0113] Emulsifier E (Inventive) 4-Cumylphenol with 12 ethylene oxide units per OH function

[0114] Preparation of the Isocyanate Reactive Mixture

[0115] [Table 3]

[0116] The ingredients (in parts by weight) listed in the table were weighed into a beaker and mixed with a disk stirrer (diameter 6 cm) at 1000 rpm for 30 seconds. 50 mL of these mixtures were then transferred into sealable measuring glass cylinders and the mixtures were observed to ensure that the blowing agent did not evaporate during storage. In case of phase separation, the thickness of the separated phases could be easily read off on the scale.

[0117] The isocyanate-reactive compositions according to the invention containing emulsifiers B to E do not show any phase separation even after storage for 14 days at room temperature.

Claims

1. A method for producing a rigid PU or PIR foam, comprising the step of contacting at least one isocyanate with an isocyanate-reactive mixture comprising at least one polyol, water and at least one emulsifier, wherein as the isocyanate, one or more organic polyisocyanates having two or more isocyanate functional groups are used, the emulsifier comprises at least one alkoxylated aromatic alcohol, the parent aromatic alcohol has at least 6 and at most 40 carbon atoms and at least one OH functional group, and at most 1 / 5 of the carbon atoms of the parent aromatic alcohol are not aromatic, and at least one aromatic unit in the parent aromatic alcohol must have an OH functional group.

2. The method according to claim 1, wherein the aromatic alcohol is ethoxylated.

3. The alkoxylated aromatic alcohol is (i) a monocyclic aromatic alcohol having one or more OH functional groups, (ii) a polycyclic aromatic system having one or more OH functional groups, (iii) a linked aromatic system having one or more OH functional groups, and / or (iv) styrenated phenol, based on the method according to claim 1.

4. The method according to claim 1, wherein at least two alkoxylated aromatic alcohols are used.

5. The alkoxylated aromatic alcohol used has 4 to 100 alkoxy groups per molecule, according to the method of claim 1.

6. The alkoxylated aromatic alcohol used has a calculated HLB value of 10 to 20, according to the method of claim 1.

7. The isocyanate-reactive mixture comprises 2% to 30% by weight of water, 1% to 30% by weight of an emulsifier, and, if any, less than 3% by weight of nonylphenol ethoxylate, according to the method of claim 1.

8. The isocyanate-reactive mixture according to claim 1, which contains a flame retardant.

9. The isocyanate-reactive mixture according to claim 1, which contains at least one catalyst.

10. A composition comprising an isocyanate-reactive mixture comprising at least one polyol, water and at least one alkoxylated aromatic alcohol, The isocyanate-reactive mixture is a composition comprising 2% to 30% by mass of water, 1% to 30% by mass of an emulsifier, and, if any, less than 3% by mass of nonylphenol ethoxylate.

11. (a) at least one alkoxylated aromatic alcohol in an amount of 20% to less than 100% by weight, (b) water in an amount of 0% to 30% by weight, (c) a carrier medium in an amount of 0% to 80% by weight comprising, an emulsifier-containing formulation, wherein the total of (b) and (c) exceeds 0% by weight.

12. Use of one alkoxylated aromatic alcohol as an emulsifier for improving the storage stability of an isocyanate-reactive mixture comprising a polyol, water and, optionally, a flame retardant.

13. A rigid PU or PIR foam produced by the method according to Claim 1.

14. A rigid PU or PIR foam which is an open-cell water-blown spray foam.