Preparation of polyurethane foams

Abstract

The invention relates to a composition for the preparation of rigid PU foams, comprising at least one polyisocyanate component, a blowing agent, a solid flame retardant, optionally a catalyst for the catalysis of the formation of urethane or isocyanurate bonds, which composition comprises at least one surfactant based on a quaternary ammonium compound.

Description

[0001] This invention relates to the field of polyurethanes, and particularly to the field of polyurethane foams. More specifically, this invention relates to the preparation of rigid polyurethane foams using solid flame retardants and surfactants based on quaternary ammonium compounds (such as ester-based quaternary ammonium salts (quat) and / or alkyl quaternary ammonium salts), to compositions for preparing such foams, and to the use of said foams. The polyurethane foam herein refers to rigid polyurethane foam.

[0002] In the context of this invention, polyurethane (PU) is specifically understood as a product obtained by reacting a polyisocyanate with a polyol or a compound having an isocyanate reactive group. In addition to polyurethane, other functional groups, such as urea diketone, carbodiimide, isocyanurate, urethane, biuret, urea, and / or urea ketone imide, can be formed in the reaction. Therefore, for the purposes of this invention, PU is understood to refer not only to polyurethane, but also to polyisocyanate, polyurea, and polyisocyanate reaction products containing urea diketone, carbodiimide, urethane, biuret, and urea ketone imide groups. In the context of this invention, polyurethane foam (PU foam) is understood to mean a foam obtained as a reaction product based on a polyisocyanate and a polyol or a compound having an isocyanate reactive group. In addition to the polyurethane of the same name, other functional groups, such as urethane, biuret, urea, carbodiimide, urea diketone, isocyanurate, or urea ketone imide, can be formed herein.

[0003] A particularly important objective related to providing PU foam (especially rigid PU foam) is to prepare PU foam with good flame-retardant properties. For this reason, flame retardants are used. Flame retardants are substances known by themselves for limiting, slowing down, or preventing the spread of fire. In the known prior art, corresponding flame retardants with flame-retardant properties and suitable for the PU foam field are described.

[0004] Recently, solid flame retardants such as ammonium polyphosphate (APP) have been increasingly used in the preparation of rigid polyurethane foams because they offer ecological and toxicological advantages compared to liquid (usually halogenated) flame retardants such as tris(2-chloroisopropyl) phosphate (TCCP). However, liquid flame retardants are easier to use. The use of solids has created considerable problems in the dispersion and processing of liquid raw materials. These include, in particular, sedimentation, redispersion after sedimentation, and uneven distribution in rigid PU foam, especially resulting in uneven property distribution within the PU foam. Efforts have been made to overcome these problems using dispersing additives, but so far no truly convincing results have been achieved. In particular, the use of dispersing additives is always accompanied by a sharp increase in component viscosity, making processing more difficult or even impossible.

[0005] In this context, the specific problem solved by the present invention is to enable the provision of rigid PU foam containing solid flame retardants, while overcoming the aforementioned problems of sedimentation, redispersion after sedimentation, and uneven distribution in the foam, and in particular avoiding excessive increase in component viscosity.

[0006] In this regard, it has been surprisingly found that, in the context of this invention, the use of surfactants based on quaternary ammonium compounds (such as ester-based quaternary ammonium salts and / or alkyl quaternary ammonium salts) can achieve the desired significant improvements in redispersion and sedimentation stability, and a more uniform performance distribution in foams. Here, the viscosity of the components is affected only to a significantly smaller extent.

[0007] The subject of this invention solves the above-mentioned problems. This invention provides a composition for preparing rigid PU foam, comprising at least one polyisocyanate component, at least one polyol component, a foaming agent, a solid flame retardant, and optionally a catalyst for catalyzing the formation of urethane or isocyanurate bonds, wherein the composition comprises at least one surfactant based on a quaternary ammonium compound (such as an ester-based quaternary ammonium salt, an alkyl quaternary ammonium salt, an amideamine quaternary ammonium salt, or an imidazoline quaternary ammonium salt).

[0008] The subject matter of this invention is associated with a variety of advantages. For example, it can provide rigid PU foam with good flame retardant properties. Advantageously, this can be achieved without adversely affecting other properties of the foam, particularly its mechanical properties. Regarding the provision of rigid PU foam, it also enables particularly microporous, uniform, and low-defect foam structures. Thus, corresponding PU foams with particularly good performance and uniform property distribution can be provided. This invention enables the particularly uniform distribution of solid flame retardants in polyurethane foam. If desired, particularly large amounts of solid flame retardants can also be added to the polyurethane foam. This invention generally makes it easy to handle solid flame retardants during foam preparation. Solid flame retardants can be introduced into the reaction mixture in a very direct manner along with surfactants based on quaternary ammonium compounds (such as preferably ester-based quaternary ammonium salts and / or alkyl quaternary ammonium salts), for example, through one of the two reaction components (a polyol component or a polyisocyanate component). Introduction via the polyol component is preferred. This invention can significantly reduce or even avoid sedimentation problems during the storage of the reaction components and the dispersion of solids. This invention also allows for very good redispersibility of solids after settling during long-term storage, meaning that continuous stirring or mixing is no longer required, for example, during storage. This invention also allows for a more uniform distribution of solids within polyurethane foam, resulting in more uniform performance properties.

[0009] Surfactants based on quaternary ammonium compounds (such as ester-based quaternary ammonium salts, amide-amine quaternary ammonium salts, imidazoline quaternary ammonium salts, hexadecylpyridine chloride, and / or alkyl quaternary ammonium salts) are known to those skilled in the art. For example, ester-based and alkyl quaternary ammonium salts are surfactants based on quaternary ammonium compounds having at least one long hydrocarbon group. Alkyl quaternary ammonium salts are typically tetraalkylammonium salts, while ester-based quaternary ammonium salts are typically based on triethanolylmethyl quaternary ammonium compounds or diethanolyldimethyl quaternary ammonium compounds esterified with at least one fatty acid.

[0010] Alkyl quaternary ammonium salts and ester quaternary ammonium salts have long been used in cosmetics or detergents and cleaning agents, such as fabric softeners, and their preparation is well known to those skilled in the art. Alkyl quaternary ammonium salts can be prepared, for example, by reacting the corresponding amine with a methylating agent such as chloromethane or dimethyl sulfate. Ester quaternary ammonium salts can be prepared, for example, by esterification of a fatty acid with methyldiethanolamine or triethanolamine, followed by quaternization, for example, with dimethyl sulfate or chloromethane.

[0011] In a particularly preferred embodiment of the invention, the surfactant based on the quaternary ammonium compound used is preferably at least one ester-based quaternary ammonium salt of formula (1) or (2), an alkyl quaternary ammonium salt of formula (3), an imidazoline quaternary ammonium salt of formula (4), an amide-amine quaternary ammonium salt of formula (5), and / or hexadecylpyridine chloride, wherein

[0012]

[0013] R 1 It is an acyl group of a straight-chain or branched fatty acid with a chain length of 8 to 22 carbon atoms, either saturated, monounsaturated, or polyunsaturated, or an acyl group of ricinoleic acid, or hydrogen.

[0014] Compounds of formula (1) or (2) may contain different groups R. 1 ,and

[0015] The condition is that at least one group R 1 It must be one of the specified acyl groups.

[0016] R 2 It is an alkyl group or hydrogen having 1 to 6 carbon atoms, preferably hydrogen, methyl, ethyl, propyl or isopropyl, more preferably hydrogen or methyl.

[0017] R 3 It is an alkyl group or hydrogen having 1 to 6 carbon atoms, preferably hydrogen, methyl, ethyl, propyl or isopropyl, more preferably methyl or hydrogen.

[0018] R 4 It is an alkyl, hydroxyethyl, or hydrogen atom having 1 to 6 carbon atoms, preferably methyl, ethyl, propyl, or isopropyl, more preferably ethyl or methyl, and very particularly preferably methyl.

[0019] Compounds of formula (1) or (2) may contain different groups R. 4 ,and

[0020] n = 0 to 20, preferably 0 to 10, more preferably 0.

[0021] a = 1 to 3 and b = 1 to 3

[0022] The condition is a + b = 4.

[0023] and / or one of them

[0024]

[0025] R 5 It is a straight-chain or branched alkyl group with a chain length of 8 to 24 carbon atoms, which is either saturated, monounsaturated, or polyunsaturated.

[0026] The compound of formula (3) can contain different groups R. 5 ,

[0027] R 6 It is an alkyl, hydroxyethyl, benzyl, or hydrogen group having 1 to 6 carbon atoms, preferably methyl, ethyl, propyl, isopropyl, or benzyl, more preferably ethyl or methyl, and very particularly preferably methyl.

[0028] The compound of formula (3) can contain different groups R. 6 ,and

[0029] c = 1 to 3 and d = 1 to 3

[0030] The condition is that c + d = 4;

[0031] and / or one of them

[0032]

[0033] R 7 It is an alkyl, hydroxyethyl, or hydrogen atom having 1 to 6 carbon atoms, preferably methyl, ethyl, propyl, or isopropyl, more preferably ethyl or methyl, and very particularly preferably methyl.

[0034] R 8 It is a straight-chain or branched alkyl group or group O(CO)R having 8 to 22 carbon atoms, whether saturated, monounsaturated, or polyunsaturated. 10 , where R 10 It is a straight-chain or branched aliphatic alkyl group having 7 to 21 carbon atoms, whether saturated, monounsaturated, or polyunsaturated.

[0035] R 9 It is a straight-chain or branched aliphatic alkyl group having 7 to 21 carbon atoms, whether saturated, monounsaturated, or polyunsaturated.

[0036] Z represents an NH group or oxygen.

[0037] e can be an integer from 1 to 4.

[0038] and / or one of them

[0039]

[0040] R 11 It is a straight-chain or branched alkyl group with a chain length of 7 to 21 carbon atoms, which is either saturated, monounsaturated, or polyunsaturated.

[0041] R 12 It is an alkyl, hydroxyethyl, or hydrogen atom having 1 to 6 carbon atoms, preferably methyl, ethyl, propyl, or isopropyl, more preferably ethyl or methyl, and very particularly preferably methyl.

[0042] The compound of formula (5) can contain different groups R. 12 ,and

[0043] f can be an integer from 0 to 5.

[0044] h = 1 or 2 and g = 2 or 3

[0045] The condition is h + g = 4.

[0046] Compounds of formula (5) with h=2 can have different f values ​​and contain different groups R. 11 ;

[0047] When R4, R6, R7 or R 12 When hydroxyethyl is included, they may also be alkoxylated, and the optionally alkoxylated hydroxyethyl may contain repeating units based on ethylene oxide, propylene oxide, butane oxide and / or phenylene oxide, and contain 1 to 15 repeating units, preferably 1 to 10 repeating units.

[0048] In view of the above-mentioned advantages of the present invention, the corresponding compositions containing the corresponding quaternary ammonium compounds show particularly advantageous results.

[0049] A further particularly preferred embodiment of the invention is that, in formula (1) and / or formula (2), R 1 Acyl groups selected from the following acids: oleic acid, isostearic acid, lauric acid, palmitic acid, elaidic acid, vaccenic acid, codoleic acid, eicosaenoic acid, docosahexaenoic acid, erucic acid, nervonic acid, linoleic acid, α-linolenic acid, γ-linolenic acid, octadecanotrienoic acid, punicic acid, α-tungsten acid, β-tungsten acid, arachidonic acid, eicosapentaenoic acid, clupanodonic acid, and / or cervonic acid.

[0050] Further preferably, in equation (1), a = b = 2 and / or in equation (5), h = 1 and g = 3. This also corresponds to another particularly preferred embodiment of the invention.

[0051] The compositions of the present invention comprise at least one counter anion of a compound of general formula (1), (2), (3), (4) and / or (5), said counter anion being selected from the group consisting of chloride ions, bromide ions, iodide ions, alkyl sulfates such as methyl sulfate, ethyl sulfate, alkyl sulfonates such as methanesulfonate, trifluoromethanesulfonate, toluenesulfonate, phosphate, sulfate, hydrogen sulfate, lactate, glycolate, acetate and / or citrate, which corresponds to another particularly preferred embodiment of the present invention.

[0052] Another particularly preferred embodiment of the invention is that, based on 100 parts of polyol, the total amount of surfactant based on quaternary ammonium compounds present in the composition of the invention is 0.1 to 10 parts, preferably 0.1 to 5 parts, more preferably 0.1 to 4 parts.

[0053] The compositions of this invention must contain at least one solid flame retardant. Solid flame retardants that can be used in rigid PU foam are also known in themselves, and the invention is not limited in its choice of solid flame retardant. However, when certain solid flame retardants are used in the compositions of this invention, it does correspond to a preferred embodiment of the invention, such a composition preferably containing melamine, melamine cyanurate, and / or phosphorus-based flame retardants such as ammonium polyphosphate or red phosphorus. Ammonium polyphosphate (APP) [CAS: 68333-79-9] is particularly preferred.

[0054] In particular, the composition of the present invention comprises a mixture of ammonium polyphosphate and melamine as a solid flame retardant, or ammonium polyphosphate coated with melamine or encapsulated in melamine, or ammonium polyphosphate microencapsulated with melamine or melamine-formaldehyde resin.

[0055] In another preferred embodiment of the invention, the total amount of solid flame retardant present in the composition of the invention is 1 to 60 parts, preferably 5 to 50 parts, and more preferably 8 to 30 parts, based on 100 parts of polyol.

[0056] Furthermore, it is particularly preferred that the compositions of the present invention further comprise at least one foam stabilizer, preferably a polyether siloxane-based foam stabilizer, based on 0.5 to 4 parts of a polyol per 100 parts. Foam stabilizers, preferably based on polyether siloxanes, are known in themselves. Suitable foam stabilizers are described below.

[0057] The present invention also provides a method for preparing rigid PU foam based on a foamable reaction mixture comprising a polyisocyanate, at least one polyol component, a foaming agent, a solid flame retardant, an optional catalyst, and optional other additives, wherein at least one surfactant based on a quaternary ammonium compound is used, preferably as described above, and preferably the composition of the present invention as described above, particularly in more detail in the preferred embodiment.

[0058] The method for preparing PU foam according to the present invention can be carried out by known methods, such as by manual mixing or preferably by a foaming machine. If the process is carried out by using a foaming machine, a high-pressure or low-pressure machine can be used. The method of the present invention can be carried out intermittently or continuously.

[0059] A particularly preferred rigid PU foam formulation for the purposes of this invention provides 5 to 900 kg / m³. 3 The foam density and composition shown in Table 1 correspond to a particularly preferred embodiment of the invention:

[0060] Table 1: Composition of Preferred Rigid PU Foam Formulations

[0061]

[0062] For further preferred embodiments and configurations of the method of the present invention, reference is also made to the details relating to the compositions of the present invention already given above.

[0063] The present invention also provides rigid PU foam prepared by the method of the present invention described above, and in particular by using the composition of the present invention.

[0064] When the foam density of the PU foam (especially rigid PU foam) of the present invention is 5 to 900 kg / m³ 3 Preferred weight is 3 to 350 kg / m³ 3 Especially 10 to 200 kg / m 3 This is a preferred embodiment of the present invention.

[0065] The present invention also relates to the use of the rigid PU foam of the present invention as an insulating material and / or as a building material, particularly in building applications, especially in the fields of spray foam or refrigeration, as sound-absorbing foam, as packaging foam, as headliner of automobiles or sleeve of pipes.

[0066] The present invention also provides the use of quaternary ammonium compound-based surfactants (particularly as defined by formulas (1), (2), (3), (4) and / or (5) above) in the preparation of rigid PU foams containing solid flame retardants, particularly when using the compositions of the present invention, especially the compositions as defined in any one of the claims. It is preferred to use surfactants based on quaternary ammonium compounds (such as ester-based or alkyl-based quaternary ammonium salts) as dispersing additives in the preparation of rigid PU foams containing solid flame retardants, particularly to improve the dispersibility, redispersibility, and / or sedimentation stability of the solid flame retardant in the compositions used to prepare rigid PU foams.

[0067] The preferred composition of the present invention comprises the following components:

[0068] a) Surfactants based on quaternary ammonium compounds, particularly those defined as in formulas (1), (2), (3), (4) and / or (5) above.

[0069] b) Isocyanate reactive components, especially polyols

[0070] c) at least one polyisocyanate and / or polyisocyanate prepolymer

[0071] d) Catalysts that accelerate / control the reaction of polyols b) with isocyanates c)

[0072] e) Optional foam stabilizers

[0073] f) One or more foaming agents

[0074] g) Solid flame retardants

[0075] h) Other optional additives, fillers, liquid flame retardants, etc.

[0076] For the purposes of this invention, suitable polyols as isocyanate-active component / polyol component b) are all organic substances and their formulations having two or more isocyanate reactive groups (preferably OH groups). Preferred polyols are all polyether polyols and / or polyester polyols and / or hydroxyl-containing aliphatic polycarbonates, particularly polyether polycarbonate polyols, and / or naturally derived polyols, referred to as "natural oil-based polyols" (NOP), which are commonly used in the preparation of polyurethane systems, particularly polyurethane coatings, polyurethane elastomers, or particularly PU foams. The functionality of the polyol is typically from 1.8 to 8, and the number average molecular weight is from 500 to 15,000. Polyols with an OH value of 10 to 1200 mg KOH / g are typically used.

[0077] For the preparation of rigid PU foam, polyols or mixtures thereof are preferably used, provided that, based on 100 parts by weight of the polyol component, at least 90 parts by weight of the polyol has an OH value greater than 100, preferably greater than 150, and particularly greater than 200. The fundamental difference between flexible and rigid foams is that flexible foams exhibit elastic behavior and are reversibly deformable. When a flexible foam is deformed by applying force, it returns to its initial shape once the force is removed. In contrast, rigid foams are permanently deformed. In the context of this invention, rigid PU foam should be understood to specifically refer to foam according to DIN 7726:1982-05, whose compressive strength according to DIN 53 421 / DIN EN ISO 604:2003-12 is advantageously ≥20 kPa, preferably ≥80 kPa, more preferably ≥100 kPa, further preferably ≥150 kPa, and particularly preferably ≥180 kPa. Furthermore, rigid PU foams according to DIN EN ISO 4590:2016-12 advantageously have a closed-cell content of more than 50%, preferably more than 80%, and more preferably more than 90%.

[0078] Polyether polyols can be prepared by known methods, for example by anionic polymerization of alkylene oxides in the presence of an alkali metal hydroxide, alkali metal alkoxide, or amine as a catalyst and by adding at least one initiator molecule preferably containing 2 or 3 linked active hydrogen atoms; or by cationic polymerization of alkylene oxides in the presence of Lewis acids such as antimony pentachloride or boron trifluoride ethers; or by bimetallic cyanide catalysis. Suitable epoxides contain 2 to 4 carbon atoms in the alkylene group. Examples are tetrahydrofuran, 1,2-epoxypropane, and 1,2- or 2,3-epoxybutane; ethylene oxide and 1,2-epoxypropane are preferred. Epoxides can be used alone, cumulatively, in blocks, alternately, or as mixtures. The starting molecule used can be, in particular, a compound having at least 2, preferably 2 to 8 hydroxyl groups, or having at least two primary amino groups in the molecule. The starting molecules used can be, for example, water, diols, triols, or tetraols, such as ethylene glycol, propane-1,2-diol and propane-1,3-diol, diethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, castor oil, etc.; higher polyfunctional polyols, especially sugar compounds, such as glucose, sorbitol, mannitol, and sucrose; polyphenols; methyl phenolic resins, such as oligomeric condensates of phenol and formaldehyde, and Mannich condensates of phenol, formaldehyde, and dialkylamines, as well as melamine or amines (such as aniline, EDA, TDA, MDA, and PMDA, more preferably TDA and PMDA). The choice of a suitable initiator molecule depends on the respective application area of ​​the resulting polyether polyol in the preparation of polyurethane.

[0079] Polyester polyols are based on esters of polyaliphatic or aromatic carboxylic acids, preferably having 2 to 12 carbon atoms. Examples of aliphatic carboxylic acids are succinic acid, glutaric acid, adipic acid, octanoic 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 iso-naphthalenedicarboxylic acid. Polyester polyols are obtained by the condensation of these polycarboxylic acids with polyols, preferably with diols or triols having 2 to 12, more preferably 2 to 6 carbon atoms, preferably trimethylolpropane and glycerol.

[0080] Polyether polycarbonate polyols are polyols containing carbon dioxide bound in the form of carbonates. Since carbon dioxide is generated in large quantities as a byproduct in many processes in the chemical industry, the use of carbon dioxide as a comonomer in alkoxide polymerization is of particular commercial interest. Partially replacing alkoxides in polyols with carbon dioxide has the potential to significantly reduce the cost of polyol preparation. Furthermore, using CO2 as a comonomer is environmentally advantageous, as the reaction constitutes a conversion of greenhouse gases into polymers. The preparation of polyether polycarbonate polyols by adding alkoxides and carbon dioxide to H-functional starting materials using catalysts is well known. Various catalyst systems can be used: the first generation is heterogeneous zinc or aluminum salts, as described, for example, in US-A3900424 or US-A 3953383. Furthermore, mononuclear and binuclear metal complexes have been successfully used for the copolymerization of CO2 and alkoxides (WO 2010 / 028362, WO 2009 / 130470, WO 2013 / 022932, or WO 2011 / 163133). One of the most important class of catalyst systems used for the copolymerization of carbon dioxide and alkoxides is the bimetallic cyanide catalyst, also known as the DMC catalyst (US-A4500704, WO 2008 / 058913). Suitable alkoxides and H-functional starting materials are also those used to prepare carbonate-free polyether polyols as described above.

[0081] Given the long-term constraints on the availability of fossil resources (i.e., oil, coal, and natural gas), and against the backdrop of rising crude oil prices, polyols based on natural oil-based (NOP) have attracted increasing attention as renewable feedstocks for the preparation of polyurethane (PU) foams, and have been described multiple times in such applications (WO 2005 / 033167; US2006 / 0293400, WO 2006 / 094227, WO2004 / 096882, US 2002 / 0103091, WO 2006 / 116456, and EP 1678232). Many of these polyols are now commercially available from various manufacturers (WO 2004 / 020497, US2006 / 0229375, WO 2009 / 058367). Depending on the base feedstock (e.g., soybean oil, palm oil, or castor oil) and subsequent processing, polyols with different properties can be obtained. Here we can basically distinguish two groups: a) polyols based on renewable raw materials, which are modified so that they can be used 100% to prepare polyurethanes (WO 2004 / 020497, US2006 / 0229375); b) polyols based on renewable raw materials, which, due to their processing and properties, can only replace petrochemical-based polyols in a certain proportion (WO 2009 / 058367).

[0082] Another class of available polyols is "filled polyols" (polymer polyols). These are characterized by containing dispersed solid organic fillers with a solids content of up to 40% or higher. Available polyols include SAN, PUD, and PIPA polyols. SAN polyols are highly reactive polyols containing dispersed copolymers based on styrene-acrylonitrile (SAN). PUD polyols are highly reactive polyols containing polyurea, also in dispersed form. PIPA polyols are highly reactive polyurethanes containing dispersed polyurethanes, for example, formed through the in-situ reaction of isocyanates with alkanolamines in conventional polyols.

[0083] Another type of usable polyol is a polyol obtained as a prepolymer by reacting a polyol with an isocyanate at a molar ratio preferably 100:1 to 5:1, more preferably 50:1 to 10:1. This prepolymer is preferably prepared in the form of a polymer solution, and the polyol preferably corresponds to the polyol used to prepare the prepolymer.

[0084] Another class of usable polyols are so-called recycled polyols, which are polyols obtained from recycled polyurethane. Recycled polyols are known in themselves. For example, polyurethane can be cleaved by solvent decomposition, thereby making it into a soluble form. Almost all chemical recycling methods for polyurethane employ such reactions, such as glycolysis, hydrolysis, acidolysis, or ammonolysis, and numerous known variations exist in the prior art. The use of recycled polyols represents a preferred embodiment of the invention.

[0085] The preferred ratio of isocyanate to polyol is expressed as a formulation index, which is the stoichiometric ratio of isocyanate groups to isocyanate reactive groups (e.g., OH groups, NH groups) multiplied by 100, and is in the range of 10 to 1000, preferably 40 to 400. An index of 100 indicates a molar ratio of reactive groups of 1:1.

[0086] The isocyanate component / polyisocyanate component c) used is preferably one or more organic polyisocyanates having two or more isocyanate functional groups. The polyol component used is preferably one or more polyols having two or more isocyanate reactive groups, preferably OH groups.

[0087] For the purposes of this invention, isocyanates suitable as isocyanate components are all isocyanates containing at least two isocyanate groups. Generally, all aliphatic, alicyclic, aryliphatic, and preferably aromatic polyfunctional isocyanates known per se can be used. Particularly preferred are isocyanates in the range of 40 to 400 mol% relative to the total amount of the component consuming the isocyanate.

[0088] Examples that may be mentioned here 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, and preferably hexamethylene 1,6-diisocyanate (HMDI), alicyclic diisocyanates such as cyclohexane 1,3- and 1,4-diisocyanates, and any desired mixtures of these isomers, 1-isocyano-3,3,5-trimethyl-5-isocyano-methylcyclohexane (abbreviated as isophorone diisocyanate). Organic diisocyanates and polyisocyanates, such as toluene 2,4-diisocyanate and hexahydrotoluene 2,6-diisocyanate and their corresponding isomers, and preferably aromatic diisocyanates and polyisocyanates, such as toluene 2,4-diisocyanate and toluene 2,6-diisocyanate (TDI) and their corresponding isomers, naphthalene diisocyanate, diethyltoluene diisocyanate, diphenylmethane 2,4'-diisocyanate and diphenylmethane 2,2'-diisocyanate (MDI) and polyphenylmethylene polyisocyanate (crude MDI), and mixtures of crude MDI and toluene diisocyanate (TDI). Organic diisocyanates and polyisocyanates can be used alone or in mixtures thereof. Corresponding "oligomers" of diisocyanates (IPDI trimers based on isocyanurates, biuret, and urea diketone) can also be used. Furthermore, prepolymers based on the above-mentioned isocyanates can be used.

[0089] Isocyanates modified by introducing urethane, diurea, isocyanurate, urethane and other groups can also be used; these are called modified isocyanates.

[0090] Organic polyisocyanates particularly suitable for and therefore especially preferred are various isomers of toluene diisocyanate (toluene 2,4-diisocyanate and toluene 2,6-diisocyanate (TDI), in pure form or as mixtures of isomers with different compositions), diphenylmethane 4,4'-diisocyanate (MDI), "crude MDI" or "polymeric MDI" (including the 4,4' isomer of MDI as well as the 2,4' and 2,2' isomers and products having more than two rings), and bicyclic products referred to as "pure MDI" which consist mainly of a mixture of 2,4' and 4,4' isomers and prepolymers derived therefrom. Particularly suitable examples of isocyanates are described in detail in, for example, EP 1712578, EP 1161474, WO 00 / 58383, US 2007 / 0072951, EP1678232 and WO 2005 / 085310, which are incorporated herein by reference in their entirety.

[0091] d) Catalyst

[0092] Catalyst d) suitable for the purposes of this invention is any compound capable of accelerating the reaction of isocyanates with OH, NH, or other isocyanate reactive groups. Conventional catalysts known in the art can be used here, including, for example, amines (cyclic, acyclic; monoamines, diamines, oligomers having one or more amino groups), ammonium compounds, organometallic compounds, and / or metal salts, preferably salts of tin, iron, bismuth, potassium, and / or zinc. In particular, mixtures of more than one component can be used as catalysts.

[0093] As an optional component e), foam stabilizers, particularly compounds containing surface-active silica, can be used. These can optionally be used to further optimize the desired cell structure and foaming process. In the context of this invention, any silica-containing compound that promotes foam generation (stabilization, cell regulation, cell opening, etc.) can be used in particular. These compounds are well known in the art. Particularly preferred is the use of at least one polyether siloxane-based foam stabilizer.

[0094] Relevant siloxane structures that can be used for the purposes of this invention are described, for example, in the following patent documents, although these documents describe their use only in conventional PU foams as molded foams, mattresses, insulation materials, building foams, etc.:

[0095] CN 103665385, CN 103657518, CN 103055759, CN 103044687, US 2008 / 0125503, US2015 / 0057384, EP 1520870 A1, EP 1211279, EP 0867464, EP 0867465, EP 0275563. These documents are incorporated herein by reference and are considered part of the disclosure of this invention.

[0096] The use of foaming agent f) is optional in principle, but preferably essential, depending on the foaming method used. Both chemical and physical foaming agents can be used. Here, the choice of foaming agent depends largely on the properties of the system.

[0097] Depending on the amount of foaming agent used, foams with high or low density can be prepared. For example, a density of 5 kg / m³ can be prepared. 3 Up to 900kg / m 3 The foam has a preferred density of 5 to 350, more preferably 10 to 200 kg / m³. 3 Especially 20 to 150 kg / m 3 .

[0098] The physical blowing agent used can be a suitable compound with a suitable boiling point. Similarly, chemical blowing agents that react with NCO groups to release gases such as water or formic acid can also be used. For the purposes of this invention, particularly preferred blowing agents include hydrocarbons having 3, 4, or 5 carbon atoms, hydrofluoroolefins (HFOs), hydrohalogenated olefins, and / or water.

[0099] Solid flame retardant g) has been described above.

[0100] The optional additives used (e.g., other additives, fillers, liquid flame retardants, etc.) can be any substance known in the art specifically for the preparation of polyurethane and PU foams, such as crosslinking agents and chain extenders, antioxidant degradation stabilizers (called antioxidants), liquid flame retardants, antimicrobial agents, cell refining additives, cell opening agents, solid fillers, antistatic additives, nucleating agents, thickeners, dyes, pigment pastes, fragrances and / or emulsifiers, etc.

[0101] The optional liquid flame retardant included in the compositions of the present invention can be any known liquid flame retardant suitable for the preparation of polyurethane foams. For the purposes of the present invention, suitable optional flame retardants are preferably liquid organophosphorus compounds, such as halogen-free organophosphates, for example triethyl phosphate (TEP), halogenated phosphates, such as tris(1-chloro-2-propyl) phosphate (TCPP) and tris(2-chloroethyl) phosphate (TCEP), and / or organophosphonates, such as dimethyl methanephosphonate (DMMP) or dimethyl propanephosphonate (DMPP). Other optional liquid flame retardants are halogenated compounds, such as halogenated polyols.

[0102] The subject matter of the invention is described below by way of examples, but the invention is not to be limited to these illustrative embodiments. When a range, formula, or class of compounds is given, these include not only the corresponding range or group of compounds explicitly mentioned, but also all subranges and subgroups of compounds that can be obtained by extracting a single value (range) or compound. When a reference is cited in the context of this specification, its entire contents, particularly with respect to the subject matter forming the context in which it is cited, are fully incorporated into the disclosure of this invention. Unless otherwise stated, percentages refer to weight percentages. Unless otherwise stated, all average values ​​are weight averages. Parameters that have been determined by measurement are specified therein, and unless otherwise stated, the measurements are performed at a temperature of 25°C and a pressure of 101,325 Pa.

[0103] The following embodiments describe the invention by way of example, and are not intended to limit the scope of the invention to the embodiments specified therein. The scope of the invention is obvious from the entire specification and claims. Example

[0104] Example 1: Settlement Stability

[0105] Performance comparisons were performed using the formulations shown in Table 2. For this purpose, 100 g of the polyol, catalyst, water, and foam stabilizer according to the examples were weighed and mixed at 1000 rpm for 30 seconds using a disc stirrer (6 cm in diameter). The compound of the present invention was then added and mixed at 2000 rpm for 30 seconds using a disc stirrer (6 cm in diameter). For the reference experiment, the same mixture (but without the compound of the present invention) was further mixed at 2000 rpm for 30 seconds. Ammonium polyphosphate, as a solid flame retardant, was then added while the disc stirrer was still running at 2000 rpm and further mixed for 45 seconds. The formulation was then transferred to a glass container and sealed, and the time until complete settling was measured.

[0106] Table 2: Formulations (components in parts by weight)

[0107]

[0108]

[0109] * R 471, obtained from Huntsman.

[0110] ** PS 3152, obtained from Stepan.

[0111] *** 4973, obtained from Coim.

[0112] # Catalyst, sourced from Evonik Operations GmbH

[0113] ## Polyether siloxane foam stabilizer, sourced from Evonik Operations GmbH

[0114] As the compound of the present invention, an ester-based quaternary ammonium salt (EQ 1) obtained by reacting diisopropanol methylamine with isostearic acid and oleic acid and then methylating it with dimethyl sulfate is used.

[0115] Table 3: Settlement Stability

[0116]

[0117] In all cases, sedimentation stability was significantly improved compared to formulations without ester-based quaternary ammonium salts.

[0118] Example 2: Redispersion

[0119] For performance comparison, the extent to which the formulations described in Example 1 can be redispersed was examined. This was accomplished by storing all formulations upright at room temperature for 14 days until the solids in all cases had completely settled. All samples were then redispersed and evaluated on a scale of 1 to 3. In this scale, 1 point indicates that the sample could be redispersed by manually shaking the glass container for 30 seconds. 2 points means that, although manual shaking was not possible, the sample could be redispersed using a laboratory electric stirrer (500 rpm, 60 s). A score of 3 is given if very fine, dense sediments formed in the sample that could not be redispersed by either of the above methods.

[0120] Table 4: Redispersibility

[0121]

[0122] In all the cases studied, the compounds of the present invention showed a significant improvement in redispersibility. In particular, the use of polyester polyols prevented the formation of dense solid deposits.

[0123] Therefore, the present invention allows for very good redispersibility of solids after settling during long-term storage, which means that, for example, continuous stirring or mixing is no longer required during storage.

[0124] Example 3: Viscosity

[0125] For comparison of processability, the effect on the viscosity of the compounds of this invention was investigated. The selected base polyol was a polyester polyol from Stepan (…). PS2352). The formulations described in Table 5 were prepared in a manner similar to that described in Example 1. The selected ester-based quaternary ammonium salt is EQ 1, the compound of the present invention described in Example 1. The selected reference additive for dispersion is Dispers 1010 (obtained from Evonik Operations GmbH). Viscosity at different shear rates was measured at 25°C using an Anton PaarMCR 302 rheometer (50 mm plate-to-plate, 0.5 mm gap).

[0126] Table 5: Viscosity (based on 1 part of APP and EQ per 100 parts of polyol)

[0127]

[0128] The use of the ester-based quaternary ammonium salt in this invention only moderately increases viscosity at low shear rates, while conventional dispersing additives result in a significant increase in viscosity. At higher shear rates, a significant reduction in viscosity can be achieved compared to conventional dispersing additives. In this embodiment, the viscosity is practically at the level of the base polyol. This offers significant advantages in terms of processing and storage, considering the technological requirements.

[0129] Example 4: Rigid PIR foam (PIR = polyisocyanurate)

[0130] The following foam formulations are used for performance comparison:

[0131] Table 6: Rigid PIR Foam Formulation

[0132] Polyester polyols* 100 Amine catalysts** 0.6 Potassium trimer catalyst*** 3 Surfactant **** 2 water 0.8 Ester-based quaternary ammonium salt EQ 1 0 or 0.5 APP 10 or 15 Cyclopentane / Isopentane 70:30 18 MDI***** 273

[0133] * PS 3152, obtained from Stepan, OH value 315 mg KOH / g

[0134] ** 5. Obtained from Evonik Operations GmbH

[0135] *** 75, acquired from Evonik Operations GmbH

[0136] **** B 84504, obtained from Evonik Operations GmbH

[0137] *****Polymerized MDI, 200 MPa*s, 31.5% NCO, functionality 2.7.

[0138] Comparative foaming was performed by manual mixing. For this purpose, the polyol, catalyst, water, foam stabilizer, optionally present ester-based quaternary ammonium salt EQ 1, ammonium polyphosphate, and foaming agent were weighed into a beaker and mixed for 30 seconds at 1000 rpm using a disc stirrer (6 cm in diameter) (batch size 500 g). The beaker was weighed again to determine the amount of foaming agent evaporated during the mixing process, and replenished. MDI was then added, and the reaction mixture was stirred at 3000 rpm for 5 seconds using the same stirrer. The mixture was immediately transferred to a 25 cm × 50 cm × 7 cm aluminum mold lined with a polyethylene film and kept at a constant temperature of 60 °C.

[0139] Ten minutes later, the foam was demolded. After one day of foaming, the foam was analyzed. Surface and internal defects were subjectively evaluated on a scale of 1 to 10, where 10 represents (idealized) defect-free foam and 1 represents foam with very obvious defects. Thermal conductivity (λ value, mW / m·K) was measured on a 2.5 cm thick disk at an average temperature of 10°C using a Hesto Lambda Control instrument (model HLC X206) according to standard EN12667:2001. Combustion performance was determined by a small burner test (B2) according to DIN 4102-1:1998-05.

[0140] The results are shown in the table below:

[0141] Table 7: Rigid PIR Foam

[0142]

[0143]

[0144] The results show that the compounds of the present invention have negligible or no effect on the relevant foam properties. Furthermore, by using the compounds of the present invention, a more uniform distribution of solid flame retardants in the foam can be achieved, resulting in significant improvements in surface and pore structure / internal defects.

[0145] Example 5: Behavior of other compounds of the present invention

[0146] Other compounds of the present invention were compared with compounds not of the present invention in a manner similar to that described in Examples 1-4.

[0147] Performance comparisons were performed using the formulations shown in Table 8.

[0148] Table 8: Rigid PIR Foam Formulation

[0149] Polyester polyols* 100 Amine catalysts** 0.6 Potassium trimer catalyst*** 5 Surfactant **** 2 water 0.8 Compounds according to the present invention 0.5 APP 10 Cyclopentane / Isopentane 70:30 18 MDI***** 286

[0150] * PS 3152, obtained from Stepan, OH value 315 mg KOH / g

[0151] ** 5. Obtained from Evonik Operations GmbH

[0152] *** TMR 12, obtained from Evonik Operations GmbH

[0153] **** B 84504, obtained from Evonik Operations GmbH

[0154] *****Polymerized MDI, 200 MPa*s, 31.5% NCO, functionality 2.7.

[0155] The compounds shown in Table 9 were investigated.

[0156] Table 9: Compounds studied

[0157]

[0158]

[0159] The compound of the present invention was combined with a commercially available non-inventory surfactant ( 6921、 8080 Dispers 652 Compare with ST).

[0160] The foam performance results shown in Table 10 were obtained in a manner similar to that described in Example 4.

[0161] Table 10: Foam Properties of Rigid PIR Foam

[0162]

[0163]

[0164] The results show that the compounds of the present invention have negligible or no effect on the relevant foam properties. Furthermore, by using the compounds of the present invention, a more uniform distribution of solid flame retardants in the foam can be achieved, resulting in a significant improvement in surface and pore structure / internal defects. On the other hand, compounds not of the present invention lead to severe foam coarsening. 6921), collapse ( 8080) or the foam structure has not improved ( Dispers 652 ST).

[0165] The results for sedimentation stability, redispersibility, and viscosity shown in Table 11 were obtained in a manner similar to that described in Examples 1 to 3. Sedimentation stability and redispersibility were determined using the formulations described in Table 8 (MDI-free, cyclo / isopentane-free). To determine viscosity, a mixture of 10 parts APP, 0.5 parts dispersant, and 100 parts polyester polyol (…) was prepared as described in Example 1. The formulation consisted of PS 3152. Viscosity was determined in a manner similar to that of Example 3.

[0166] Table 11: Dispersed Behavior

[0167]

[0168]

[0169] In all cases studied, improved sedimentation stability and redispersibility were achieved compared to formulations without the compounds of the present invention, and compared to surfactants not of the present invention.

[0170] In particular, the use of polyester polyols prevents the formation of dense solid deposits.

[0171] Using the compounds of the present invention only moderately increases viscosity at low shear rates, while compounds not of the present invention cause a significant increase in viscosity, thus making processing more difficult.

Claims

1. A composition for preparing rigid PU foam, comprising at least one polyisocyanate component, at least one polyol component, a foaming agent, a solid flame retardant, and optionally a catalyst for catalyzing the formation of urethane or isocyanurate bonds, characterized in that... The composition comprises at least one surfactant based on a quaternary ammonium compound. The quaternary ammonium compound used is at least one ester-based quaternary ammonium salt of formula (1) or (2), an alkyl quaternary ammonium salt of formula (3), an imidazoline quaternary ammonium salt of formula (4), an amide-amine quaternary ammonium salt of formula (5), and / or hexadecylpyridine chloride. in Equation (1), Equation (2) R 1 It is an acyl group of a straight-chain or branched fatty acid with a chain length of 8 to 22 carbon atoms, either saturated, monounsaturated, or polyunsaturated, or an acyl group of ricinoleic acid, or hydrogen. and The condition is that at least one group R 1 It must be one of the specified acyl groups. R 2 It is an alkyl group or hydrogen with 1 to 6 carbon atoms. R 3 It is an alkyl group or hydrogen with 1 to 6 carbon atoms. R 4 It is an alkyl, hydroxyethyl, or hydrogen atom having 1 to 6 carbon atoms. and n = 0 to 20, a = 1 to 3 and b = 1 to 3 The condition is a + b = 4. and / or one of them Equation (3) R 5 It is a straight-chain or branched alkyl group with a chain length of 8 to 24 carbon atoms, which is either saturated, monounsaturated, or polyunsaturated. R 6 It is an alkyl, hydroxyethyl, benzyl, or hydrogen group having 1 to 6 carbon atoms. and c = 1 to 3 and d = 1 to 3 The condition is that c + d = 4. and / or one of them Equation (4) R 7 It is an alkyl, hydroxyethyl, or hydrogen atom having 1 to 6 carbon atoms. R 8 It is a straight-chain or branched alkyl group or group O(CO)R having 8 to 22 carbon atoms, whether saturated, monounsaturated, or polyunsaturated. 10 , where R 10 It is a straight-chain or branched aliphatic alkyl group having 7 to 21 carbon atoms, whether saturated, monounsaturated, or polyunsaturated. R 9 It is a straight-chain or branched aliphatic alkyl group having 7 to 21 carbon atoms, whether saturated, monounsaturated, or polyunsaturated. Z represents an NH group or oxygen. Where e is an integer from 1 to 4, and / or one of them Equation (5) R 11 It is a straight-chain or branched alkyl group with a chain length of 7 to 21 carbon atoms, which is either saturated, monounsaturated, or polyunsaturated. R 12 It is an alkyl, hydroxyethyl, or hydrogen atom having 1 to 6 carbon atoms. and f is an integer from 0 to 5. h=1 or 2 and g=2 or 3 The condition is h + g = 4.

2. The composition according to claim 1, wherein the compound of formula (1) or (2) comprises different groups R. 1 , And / or, compounds of formula (1) or (2) contain different groups R. 4 , And / or, compounds of formula (3) contain different groups R 5 , And / or, compounds of formula (3) contain different groups R 6 , And / or, compounds of formula (5) contain different groups R 12 .

3. The composition according to claim 1, wherein R 2 It is hydrogen, methyl, ethyl, propyl, or isopropyl. And / or, R 3 It is hydrogen, methyl, ethyl, propyl, or isopropyl. And / or, R 4 It is methyl, ethyl, propyl, or isopropyl. And / or, R 6 It is methyl, ethyl, propyl, isopropyl, or benzyl. And / or, R 7 It is methyl, ethyl, propyl, or isopropyl. And / or, R 12 It is methyl, ethyl, propyl or isopropyl.

4. The composition according to claim 1, wherein R 2 It is hydrogen or methyl. And / or, R 3 It is methyl or hydrogen. And / or, R 4 It is ethyl or methyl. And / or, R 6 It is ethyl or methyl. And / or, R 7 It is ethyl or methyl. And / or, R 12 It is either ethyl or methyl.

5. The composition according to claim 1, wherein R 4 It is methyl. And / or, R 6 It is methyl. And / or, R 7 It is methyl And / or, R 12 It is a methyl group.

6. The composition according to claim 1, wherein n = 0 to 10.

7. The composition according to claim 1, wherein n = 0.

8. The composition according to claim 1, wherein the compounds of formula (5) with h=2 have different f values ​​and contain different groups R. 11 .

9. The composition according to claim 1, wherein when R 4 R 6 R 7 or R 12 When hydroxyethyl is included, they are alkoxylated.

10. The composition of claim 9, wherein the alkoxylated hydroxyethyl comprises repeating units based on ethylene oxide, propylene oxide, butane oxide, and / or styrene oxide, and comprises 1 to 15 repeating units.

11. The composition according to claim 10, wherein, The alkoxylated hydroxyethyl contains 1-10 repeating units.

12. The composition according to claim 1, characterized in that, In equation (1) and / or equation (2), R 1 The acid is selected from the acyl group of an acid, which is selected from the group consisting of oleic acid, isostearic acid, lauric acid, palmitic acid, transoleic acid, isoleic acid, eicosapentaenoic acid, eosinophilic acid, linoleic acid, octadecanetrienoic acid, punicic acid, arachidonic acid, eicosapentaenoic acid, stigmacooleic acid, and / or docosahexaenoic acid.

13. The composition according to claim 12, wherein the acid is selected from the group consisting of codoleic acid, erucic acid, α-linolenic acid, γ-linolenic acid, α-tungsten acid, and / or β-tungsten acid.

14. The composition according to any one of claims 1 to 13, characterized in that, In equation (1), a = b = 2 and / or in equation (5), h = 1 and g = 3.

15. The composition according to any one of claims 1 to 13, further comprising at least one counterion to compounds of general formulas (1), (2), (3), (4) and / or (5), said counterion being selected from the group consisting of chloride, bromide, iodide, alkyl sulfate, alkyl sulfonate, trifluoromethanesulfonate, toluenesulfonate, phosphate, sulfate, hydrogen sulfate, lactate, glycolate, acetate and / or citrate.

16. The composition according to claim 15, wherein the alkyl sulfate is methyl sulfate or ethyl sulfate. And / or the alkyl sulfonate group is a methanesulfonate group.

17. The composition according to any one of claims 1 to 13, characterized in that, The total amount of the surfactant based on the quaternary ammonium compound present is from 0.1 to 10 parts.

18. The composition of claim 17, wherein the total amount of the surfactant based on the quaternary ammonium compound is 0.1 to 5 parts.

19. The composition of claim 17, wherein the total amount of the surfactant based on the quaternary ammonium compound is 0.1 to 4 parts.

20. The composition according to any one of claims 1 to 13, characterized in that, The composition contains the following substances as solid flame retardants: ammonium polyphosphate, melamine, melamine cyanurate and / or red phosphorus.

21. The composition of claim 20, wherein the composition comprises ammonium polyphosphate as a solid flame retardant.

22. The composition according to any one of claims 1 to 13, characterized in that, The composition comprises the following substances as solid flame retardants: ammonium polyphosphate and melamine, or ammonium polyphosphate coated with melamine or encapsulated in melamine, or ammonium polyphosphate microencapsulated with melamine or melamine-formaldehyde resin.

23. The composition according to any one of claims 1 to 13, characterized in that, The total amount of the solid flame retardant is between 1 and 60 parts based on 100 parts of polyol.

24. The composition according to claim 23, wherein the total amount of the solid flame retardant is 5 to 50 parts based on 100 parts of polyol.

25. The composition according to claim 23, wherein the total amount of the solid flame retardant is 8 to 30 parts based on 100 parts of polyol.

26. The composition according to any one of claims 1 to 13, characterized in that, The composition further comprises at least one foam stabilizer, based on 100 parts of polyol, wherein the amount of the foam stabilizer is from 0.5 to 4 parts.

27. The composition of claim 26, wherein the foam stabilizer is a polyether siloxane foam stabilizer.

28. A method for preparing rigid PU foam based on a foamable reaction mixture, said reaction mixture comprising a polyisocyanate, at least one polyol component, a foaming agent, a solid flame retardant, an optional catalyst, and optional other additives, characterized in that... Use at least one surfactant based on a quaternary ammonium compound as defined in any one of claims 1 to 16.

29. A method for preparing rigid PU foam based on a foamable reaction mixture, said reaction mixture comprising a polyisocyanate, at least one polyol component, a foaming agent, a solid flame retardant, an optional catalyst, and optional other additives, characterized in that... Use at least one surfactant based on a quaternary ammonium compound, wherein the composition is used as defined in any one of claims 1 to 27.

30. Rigid PU foam prepared according to the method of claim 28 or 29.

31. Use of the rigid PU foam according to claim 30 as an insulating material and / or as a building material, as a sound-absorbing foam, as a packaging foam, as a headliner of an automobile, or as a pipe sleeve.

32. The use of the rigid PU foam according to claim 30 as an insulating material and / or as a building material, wherein it is used in building applications.

33. The use of the rigid PU foam according to claim 30 as an insulating material and / or as a building material, in the fields of spray foam or refrigeration.

34. Use of a quaternary ammonium compound-based surfactant, which is the quaternary ammonium compound-based surfactant as defined in any one of claims 1 to 16, as a dispersing additive in the preparation of rigid PU foam comprising a solid flame retardant.

35. Use of surfactants based on quaternary ammonium compounds as dispersing additives in the preparation of rigid PU foams containing solid flame retardants, wherein the composition according to any one of claims 1 to 27 is used.

36. Use of a quaternary ammonium compound-based surfactant to improve the dispersibility, redispersibility and / or sedimentation stability of a solid flame retardant in a composition for preparing rigid PU foam, as described in claim 34 or 35.

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