Production of polyurethane foam

Abstract

The invention relates to (a) a composition suitable for producing polyurethane foam, comprising at least one polyisocyanate component, a polyol component, optionally a catalyst that catalyzes the forming of a urethane or isocyanurate bond, and optionally a blowing agent, the composition additionally comprising hydrocarbons KWS, Si-free surfactant and optionally polyalkyl siloxane, (b) to a method for producing polyurethane foam by using hydrocarbons KWS, Si-free surfactant and optionally polyalkyl siloxanes, (c) to the polyurethane foam thereby obtained, and (d) to the use thereof.

Description

Production of polyurethane foam The present invention is in the field of polyurethane foams. In particular, it relates to the production of polyurethane foams using specific hydrocarbons and Si-free surfactant, as well as to the use of the foams produced therewith. For the purposes of the present invention, polyurethane (PU) is understood to mean, in particular, a product obtainable by reacting polyisocyanates and polyols or compounds containing isocyanate-reactive groups. In addition to the polyurethane, other functional groups can also be formed, such as uretdiones, carbodiimides, isocyanurates, allophanates, biurets, ureas and / or uretimines. Therefore, PU for the purposes of the present invention is understood to mean polyurethane as well as polyisocyanurate, polyureas and polyisocyanate reaction products containing uretdione, carbodiimide, allophanate, biuret and uretimine groups. For the purposes of the present invention, polyurethane foam (PU foam) is understood to mean, in particular, foam obtained as a reaction product based on polyisocyanates and polyols or compounds containing isocyanate-reactive groups.In addition to the name-giving polyurethane, other functional groups can also be formed, such as allophanates, biurets, ureas, carbodiimides, uretdiones, isocyanurates or uretimines. Polyurethane foam is also commonly referred to as polyurethane foam. The terms "foam" and "foam material" are therefore used synonymously here. In the production of polyurethane and polyisocyanurate foams, cell-stabilizing additives are commonly used to ensure a fine-cell, uniform, and low-interference foam structure, thus significantly improving the performance properties, especially the thermal insulation capacity of the foam. Polyethersiloxane (PES) foam stabilizers are typically used, especially for rigid foam applications. These Si-containing surfactants are considered the preferred choice. They therefore generally represent the preferred type of foam stabilizer. However, the use of Si-free surfactants is also described in numerous publications. EP 2511328 B1 describes the use of carbamates as surfactants for foam stabilization. DE 1020011007479 A1 describes mixtures of acid amides with PES for use as foam stabilizers in rigid PU foam. In EP 1985642, amidoamines and imidazoles based on carboxylic acids and polyethylene or polypropylene amines, such as diethylenetriamine, triethylenetetramine or tetraethylenepentamine, are used as additives for the production of PU foams. US 3746663 describes the use of N-vinylpyrrolidone-based structures for use as a surfactant in PU foam production. DE 3724716 C1 describes the use of novolak-based ethoxylates as stabilizers in PU foam production. EP 0734404 describes the production of PU foams using polyalkylene oxides, wherein the polyalkylene oxides are built up by using 10-90% butylene oxide. EP 1985642 describes a composition for producing PU foam using amidamines and / or imidazoles based on C1-C36 carboxylic acids. US 5236961 describes the production of polyurethane foams using alkylphenol ethoxylates as foam stabilizers DE 2244350 A1 describes the use of copolymers prepared from N-vinylpyrrolidone and maleic acid esters for the production of polyurethane foam. The use of Si-free surfactants in PU foams is therefore well known. Nevertheless, experts have previously assumed that Si-free surfactants lead to reduced foam quality compared to Si-containing surfactants, especially compared to polyether-modified siloxanes (PES). Especially when PU foams are required to achieve good insulation performance, i.e., a low lambda value, Si-containing surfactants, especially polyether-modified siloxanes (PES), often have an advantage over Si-free surfactants. However, the use of Si-containing surfactants, especially polyether-modified siloxanes (PES), can also have disadvantages. For example, they can impair the solubility of blowing agents (e.g., pentanes) in the polyols. This is particularly pronounced when the PES contains a high siloxane content and is therefore highly hydrophobic. Furthermore, Si-containing surfactants are not based on renewable raw materials and are therefore disadvantageous from a sustainability perspective. There was therefore a desire to provide PU foams with high foam quality or good insulation performance without the need for the use of Si-containing surfactants. In addition to the use of Si-free surfactants in PU foams, the use of hydrocarbons in PU foams is also well known. For example, hydrocarbons are often used as blowing agents in PU foams. In this case, Compounds with a maximum of 7, particularly 3 to 7, carbon atoms are used because these have boiling points in the appropriate temperature range, allowing them to evaporate during the foaming process and thus contribute to the increase in volume, i.e., foam formation. In the finished foam, these blowing agents are still present as cell gas. The use of these hydrocarbons is described in numerous publications. US 20110218259 describes the use of cyclopentane in PU rigid foam systems with improved flowability, such as those required in the production of refrigeration units or panels. EP 421269 describes the use of cyclopentane and mixtures thereof with cyclohexane and various hydrocarbons with a maximum of four carbon atoms, as well as ethers and fluoroalkanes with a boiling point below 35°C. Hydrocarbons are used here, all of which evaporate during PU foaming and thus serve as blowing agents. WO 2016202912 describes various hydrocarbons as well as ethers, ketones, esters, acetals, and fluoroalkanes as blowing agents. Preferably, their boiling points are below 50°C. CN 101880452 describes the use of alkanes with 14 to 21 carbon atoms as phase-change materials used as fillers in amounts of 10 to 30 parts per 100 parts of polyol. No effects on the quality of a PU foam produced with these materials regarding its thermal conductivity are described. JP 09165427 describes the use of alkanes with 9 to 12 carbon atoms to improve the storage stability of the polyol mixture, especially when pentane is used as a blowing agent. 1 to 10 parts of the alkanes are used per 100 parts of polyol. No effects on the quality of a PU foam produced with this mixture, with regard to its thermal conductivity, are described. US 20070066697 describes flexible PU foams that achieve improved compression strength through the use of hydrocarbons with 10 to 70 carbon atoms. Dosages range from 0.01 to 100 pphp, 1 to 25 pphp, and 2 to 8 pphp (pphp = parts per hundred polyol). JP 04018431 describes the use of non-reactive components such as paraffins or other hydrocarbons, added in quantities of 0.1 to 10 pphp, in rigid PU foam to improve the foam's aging performance with respect to the lambda value. The examples show that the initial lambda values ​​deteriorate with the addition of paraffin. EP 3677610 describes the use of special hydrocarbons in combination with polyether-modified siloxanes as surfactants to obtain rigid PU foams with improved properties. This combination is disclosed as mandatory. No possibility is described of achieving improved properties of rigid PU foams without polyether-modified siloxanes. None of the above-mentioned documents discloses the combined use of certain hydrocarbons (HCs), which have boiling points > 100°C at atmospheric pressure, and Si-free surfactants (SiS). The object of the present invention was to overcome at least one disadvantage of the prior art. In particular, the object was to provide polyurethane or polyisocyanurate foams that exhibit particularly advantageous properties, such as, in particular, low thermal conductivity (good insulation performance) and / or high foam quality, especially good surface quality, without having to use Si-containing surfactants. Surprisingly, it has now been discovered that the use of Si-free surfactants does not lead to reduced foam quality when combined with special hydrocarbons (KWS) that have boiling points > 100°C at atmospheric pressure. In particular, the use of special hydrocarbons (KWS) allows PU foams with improved lambda values ​​to be produced without the need for Si-containing surfactants such as polyether-modified siloxanes. The task is therefore solved by the combined use of certain hydrocarbons (HCs), which have boiling points > 100°C at normal pressure, and Si-free surfactants (SifS). By combining certain hydrocarbons (HCWs), which have boiling points > 100°C at atmospheric pressure, with silicon-free surfactants, PU foams with improved performance properties (especially lambda values) can be produced. In particular, low thermal conductivity and / or good surface quality are achieved. Furthermore, good cell density is achieved. Foam defects can be reduced. With the present invention, PU foam-based products such as insulation panels or refrigeration units can be manufactured with higher quality, and the manufacturing processes can be made more efficient. Even a very small addition of hydrocarbons (HCs) according to the invention, in combination with Si-free surfactants (SiFS), enables corresponding improvements. A first subject of the invention is therefore a composition for producing polyurethane foam, comprising at least one polyisocyanate component, a polyol component, optionally a catalyst which catalyzes the formation of a urethane or isocyanurate bond, optionally a blowing agent, wherein the composition additionally comprises hydrocarbons KWS which have boiling points >100°C, preferably >150°C, at atmospheric pressure (1.01325 bar), and Si-free surfactant. Another object of the invention is a process for producing polyurethane foam by reacting one or more polyol components with one or more polyisocyanate components, characterized in that the reaction takes place in the presence of hydrocarbons KWS, Si-free surfactant and optionally polyalkyl siloxanes, in particular using the composition according to the invention. Yet another object of the invention is the use of a combination of hydrocarbons KWS, Si-free surfactant and optional polyalkyl siloxanes for producing polyurethane foams, preferably as a foam stabilizer, preferably for improving the insulating properties of the polyurethane foam, in particular using the composition according to the invention. Yet another object of the invention is a polyurethane foam obtainable by the process according to the invention. According to a preferred embodiment, the polyurethane foam obtainable according to the invention has lambda values ​​(in mW / mK) of less than 24, preferably less than 23, in particular less than 22. The thermal conductivity, which is the lambda value (A value in mW / m K) can be determined within the scope of this invention preferably according to the specifications of the standard EN 12667:2001-05, in particular as stated in the experimental part. Yet another object of the invention is the use of the polyurethane foam according to the invention as insulation boards and / or insulation materials, preferably for cooling equipment. Advantageous embodiments of the subject matter of the invention can be gathered from the claims, the examples and the description. Furthermore, it is expressly pointed out that the disclosure of the subject matter of the present invention includes all combinations of individual features of the present or subsequent description of the invention and the patent claims. In particular, embodiments of an inventive Subject matter mutatis mutandis also for the embodiments of the other subject matters according to the invention. The hydrocarbons KWS according to the invention have boiling points of above 100°C, preferably above 150°C, at atmospheric pressure (1.01325 bar). It is preferred that boiling points at atmospheric pressure are below 400°C, preferably below 350°C. The hydrocarbons KWS therefore preferably have boiling points of >100°C to <400°C, in particular >100°C to <350°C, at atmospheric pressure. The hydrocarbons KWS consist of carbon atoms, hydrogen atoms and optionally a maximum of 3 heteroatoms selected from the group consisting of oxygen, nitrogen and sulfur atoms. The hydrocarbons KWS, if they contain heteroatoms, preferably only have oxygen atoms as heteroatoms. It is preferred that the hydrocarbons KWS have one or no heteroatom, where the heteroatom is an oxygen atom. However, it is even more preferred that the hydrocarbons KWS do not contain any heteroatoms.It is therefore particularly preferred that the hydrocarbons (HCs) consist exclusively of carbon atoms and hydrogen atoms. Both saturated and unsaturated hydrocarbons (HCs) can be used. Aliphatic or aromatic hydrocarbons (HCs) can be used. The hydrocarbons (HCs) can be branched or unbranched. They can be cyclic or acyclic hydrocarbons (HCs). Preferred hydrocarbons (KWS) are olefins, paraffins, isoparaffins, or alkylbenzenes, according to a preferred embodiment of the invention. Such materials are available, for example, from Sasol under the trade names: HF-1000, LINPAR, SASOLAB, and PARAFOL. The hydrocarbons (HCs) according to the invention are preferably hydrocarbons (branched or unbranched, saturated or unsaturated, cyclic or acyclic, aliphatic or aromatic) having 10 to 24 carbon atoms. These can be prepared, for example, by oligomerization of olefins as described in US 4647707, DE102008007081 A1, and DE102013212481A1. Likewise, corresponding material streams arising in the production of oxo alcohols can be used, as described in US 4647707, EP1515934B1, and EP2947064A1. Oxo oils, which are called intermediates or by-products, occur as a result. Paraffin- and olefin-containing distillation fractions, such as the so-called light oxo fraction, as described in US 4647707, are preferred. The hydrocarbons KWS according to the invention are very particularly preferably selected from the group consisting of decene, dodecene, dodecane, isododecane, tetradecane, tributene, tributene, tetrabutene, tetrabutane, alkylbenzenes having at least 10 carbon atoms and oxo oils. Hydrocarbons produced from renewable raw materials can also be used, such as isododecane from Global Bioenergies, which was produced according to the process described in WO 2021 / 228824. Particularly suitable hydrocarbons KWS are described in EP 3677610 B1, in particular in section

[0112] , According to the invention, the hydrocarbons are used in combination with Si-free surfactants (SiS). The term “Si-free” means that the surfactants do not contain any silicon atoms. The Si-free surfactants are preferably compounds consisting of carbon atoms, hydrogen atoms and heteroatoms selected from oxygen atoms and nitrogen atoms. Surfactants (surface active agents) are also referred to as surface-active agents or surfactants. In the context of the present invention, the term “surfactants” refers to substances which, when added, reduce the surface tension of water. It is preferred that the Si-free surfactant be used at a concentration of 0.5 wt.-% in water (i.e. 0.5 parts by weight of Si-free surfactants to 99.5 parts by weight of water) reduces the static surface tension of this surfactant-water mixture at a temperature of 20 °C and preferably at normal pressure (1.01325 bar) to less than 70 mN / m, preferably to less than 60 mN / m, even more preferably to less than 60 mN / m, even more preferably to less than 50 mN / m, particularly preferably to less than 40 mN / m. It is therefore preferred that a mixture of 5 parts of the Si-free surfactant in 995 parts of water at a temperature of 20 °C and preferably at normal pressure (1.01325 bar) has a static surface tension of less than 70 mN / m, preferably less than 60 mN / m, more preferably less than 60 mN / m, more preferably less than 50 mN / m, particularly preferably less than 40 mN / m.The static surface tension is preferably determined according to DIN EN 14370:2004-11 (Surface-active agents - Determination of surface tension; German version EN 14370:2004). Preferably, the determination according to DIN EN 14370:2004-11 is carried out as follows: The surfactants are measured in double-distilled water. The surfactant-water mixtures are calculated to 100 ml and weighed on the analytical balance. If foam forms on the sample, it is removed with a pipette. A K100MK2 tensiometer from Krüss is used for the measurements, along with a Krüss standard plate (Pt, 19.900 x 0.200 x 10.000 mm) for the plate method or a Krüss standard ring (du Noüy) (Pt, r=9.545 mm, thickness 0.370 mm) for the ring method, with the ring method being preferred. For calibration, double-distilled water type I (resistivity 18.2 MΩcm, TOC content < 5 ppb, TOC = total organic carbon) from Millipore Simplicity UV from Millipore and 1-octanol ≥ 99% from Sigma-Aldrich are used. The Si-free surfactants can be selected from the group consisting of non-ionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants (zwitterionic surfactants). In general, any Si-free surfactants can be used. Preferably, Si-free surfactants are those known to be suitable for use in the production of PU foams, especially rigid PU foams. Here, it may also be preferable to use substances based on renewable raw materials. For example, EP2295485 A1 describes the use of lecithin as a surfactant for the production of rigid PU foam, which can also be used here as a Si-free surfactant (SiFS). Preferably, the Si-free surfactants are selected from the group of non-ionic surfactants. For example, the following non-ionic surfactants can be used: A preferred class of Si-free surfactants is based on carboxylic acids, which represent the hydrophobic part of the surfactant. In this case, the Si-free surfactants are carboxylic acid derivatives. The carboxylic acids can be derivatized, i.e., chemically bonded, in various ways, such as as esters, amides, imides, imidazolines, oxazolines, etc., depending on the species with which the carboxylic acids or carboxylic acid derivatives were reacted to produce the Si-free surfactant. It is therefore preferred that the Si-free surfactant is a carboxylic acid derivative selected from the group consisting of esters, amides, imides, imidazolines and oxazolines. As carboxylic acids, for example, monocarboxylic acids, dicarboxylic acids, tricarboxylic acids, tetracarboxylic acids based on aliphatic or aromatic hydrocarbons or their derivatives can be used. It is preferred that the carboxylic acids have 6 to 40 carbon atoms, in particular 8 to 22 carbon atoms. The carboxylic acids can be saturated or unsaturated, cyclic or acyclic, linear or branched, aromatic or aliphatic. The carboxylic acids can also contain one or more double bonds and / or OH functions. It is therefore preferred that the Si-free surfactants are carboxylic acid derivatives of carboxylic acids having 6 to 40, in particular 8 to 22, carbon atoms, wherein the carboxylic acid derivatives are selected from the group consisting of esters, amides, imides, imidazolines and oxazolines. These Carboxylic acid derivatives comprise the carbon skeleton of the underlying carboxylic acid as a structural element. The oxygen atoms of the carboxyl group of the underlying carboxylic acid are replaced by heteroatoms selected from oxygen atoms and nitrogen atoms.It is preferred that the carboxylic acids are selected from the group consisting of caproic acid (hexanoic acid), caprylic acid (octanoic acid), capric acid (decanoic acid), lauric acid (dodecanoic acid), myristic acid (tetradecanoic acid), palmitic acid (hexadecanoic acid), stearic acid (octadecanoic acid), arachidic acid (eicosanoic acid), behenic acid (docosanoic acid), lignoceric acid (tetracosanoic acid), palmitoleic acid ((Z)-9-hexadecenoic acid), oleic acid ((Z)-9-hexadecenoic acid), elaidic acid ((E)-9-octadecenoic acid), cis-vaccenoic acid ((Z)-11-octadecenoic acid), linoleic acid ((9Z,12Z)-9,12-octadecadienoic acid), alpha-linolenic acid ((9Z,12Z,15Z)-9,12,15-octadecatrienoic acid), gamma-linolenic acid ((6Z,9Z,12Z)-6,9,12-octadecatrienoic acid), di-homo-gamma-linolenic acid ((8Z,11Z,14Z)-8,11,14-eicosatrienoic acid), arachidonic acid ((5Z,8Z,11Z,14Z)-5,8,11,14-eicosatetraenoic acid), erucic acid ((Z)-13-docosenoic acid), nervonic acid ((Z)-15-tetracosenoic acid), ricinoleic acid, hydroxystearic acid and undecenylic acid, as well as mixtures thereof, such asRapeseed oil acid, soybean fatty acid, sunflower fatty acid, peanut fatty acid, and tall oil fatty acid. Dimer and oligomer fatty acids, such as those produced by the oligomerization of unsaturated fatty acids, can also be used. Sources of suitable fatty acids or fatty acid esters, especially glycerides, can be vegetable or animal fats, oils, or waxes. Examples include: lard, beef tallow, goose fat, duck fat, chicken fat, horse fat, whale oil, fish oil, palm oil, olive oil, avocado oil, seed kernel oils, coconut oil, palm kernel oil, cocoa butter, cottonseed oil, pumpkin seed oil, corn germ oil, sunflower oil, wheat germ oil, grape seed oil, sesame oil, linseed oil, soybean oil, peanut oil, lupin oil, rapeseed oil, mustard oil, castor oil, jatropa oil, walnut oil, jojoba oil, lecithin, etc.based on soy, rapeseed or sunflower, bone oil, neatsfoot oil, lanolin, emu oil, deer tallow, marmot oil, mink oil, borage oil, thistle oil, hemp oil, pumpkin oil, evening primrose oil, tall oil, as well as carnauba wax, beeswax, candelilla wax, ouricuri wax, sugar cane wax, retamo wax, caranday wax, raffia wax, esparto wax, alfalfa wax, bamboo wax, hemp wax, Douglas fir wax, cork wax, sisal wax, flax wax, cotton wax, dammar wax, tea wax, coffee wax, rice wax, oleander wax, beeswax and / or wool wax. A preferred selection of Si-free surfactants is based on the above-mentioned carboxylic acids, which are converted into esters, amides, imides, imidazolines, oxazolines or other structures via various chemical reactions. Preferred carboxylic acid-based Si-free surfactants are listed below: In a preferred embodiment, the Si-free surfactants are carboxylic acid esters of polyethers, preferably selected from the group consisting of PEG 400 dicocoate, PEG 500 monomethyl ether cocoate, PEG 500 monomethyl ether laurate, PEG-8 ricinoleate, PEG-7 glyceryl cocoate, PEG-30 glyceryl cocoate, PEG-30 glyceryl stearate, PEG-80 glyceryl cocoate, dipropylene glycol dibenzoate, PEG-55 propylene glycol oleate, PEG-18 glyceryl oleate, PEG-150 distearate, glycol distearate, PEG-40 stearate and sucrose stearate. In a further preferred embodiment, the Si-free surfactants are carboxylic acid esters of glycerin or polyglycerin, preferably selected from the group consisting of glyceryl stearate, glyceryl oleate, polyglyceryl-4 diisostearate, polyglyceryl-4 isostearate, polyglyceryl-3 oleate, polyceryl oleic acid ester; polyceryl fatty acid partial ester, diisostearoyl polyglyceryl-3 dimer dilinoleate, polyglyceryl-4 laurate and polyglyceryl-3 caprylate. In a further preferred embodiment, the Si-free surfactants are alkoxylated or non-alkoxylated carboxylic acid esters of sorbitan, preferably selected from the group consisting of sorbitan laurate, polysorbate 20, polysorbate 80, sorbitan oleate, sorbitan stearate and sorbitan trioleate. Sorbitan esters have long been known as emulsifiers. Sorbitol is a reduced polyol form of glucose and is also known as sorbitol or glucitol. Sorbitol can undergo self-condensation with the elimination of water, forming what is known as sorbitan. Sorbitan is generally understood to be a product mixture of the self-condensation products of sorbitol; these are essentially five- and six-membered, mono- and bicyclic, hydroxy-functional ethers of polyol nature. Sorbitan carboxylic acid esters are the carboxylic acid esters of sorbitan and thus the acylation products of the product mixture described above. The product mixture is usually acylated with 1 to 3 mol of carboxylic acid per 1 mol of product; however, substoichiometric acylations are also conceivable, in which the product mixture is acylated with less than 1 mol of carboxylic acid. In another preferred embodiment, the Si-free surfactants are carboxylic acid amides. Amides can be prepared from a wide variety of amines and the above-mentioned carboxylic acids. Suitable amines for amidation are, for example, amines with at least one primary or secondary amine function, which may optionally contain one or more hydroxy groups. Suitable amines are therefore, for example: ethylenediamine, diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), dipropylenetriamine, tripropylenetetramine, tetrapropylenepentamine, pentapropylenehexamine, hexapropyleneheptamine, as well as higher homologues based on ethylenediamine or propylenediamine, 1,2-propylenediamine, 4,4'-diaminodicyclohexylmethane, 3,3'-di- methyl-4,4'-diaminodicyclohexylmethane, 4,4-methylenediphenylenediamine, isophoronediamine, trimethylhexymethylenediamine, neopentanediamine, octamethylenediamine, polyetheramines such as Polyetheramine D 2000 (BASF), Polyetheramine D 230 (BASF), Polyetheramine T 403 (BASF), Polyetheramine T 5000 (BASF) or corresponding Jeffamine types from Huntsman, piperazine, aminoethylpiperazine, bis(aminoethyl)piperazine, 1,3-diaminopropane, 3-(cyclohexylamino)propylamine, 3-(methylamino)propylamine, N,N-bis-(3-aminopropyl)methylamine, (3-(2-aminoethylamino)propylamine), dipropylenetriamine, (N,N'-bis-(3-aminopropyl)-ethylenediamine. Suitable hydroxylamines containing at least one OH function are, for example: ethanolamine, propanolamine, alkylethanolamines, arylethanolamine, alkylpropanolamine, such as: diethanolamine, monoethanolamine, diisopropanolamine, isopropanolamine, Methylisopropanolami, digylcolamine (2-(2-aminoethoxy)ethanol), dimethylethanolamine, N-(2-hydroxyethyl)aniline, 1-(2-hydroxyethyl)piperazine, 2-(2-aminoethoxy)ethanol, 3-amino-1-propanol, 5-amino-1-pentanol, butylethanolamine, ethylethanolamine, N-Methylethanolamine, Aminopropyl- monomethylethanolamine, 2-Amino-2-methylpropanol, Trishydroxymethylaminomethane (THMAM or TRIS), N-(2-Aminoethyl)ethanolamine (AEEA). It is also possible to use corresponding alkoxylates, in particular ethoxylates and / or propoxylates of amines, such as alkylamines having a hydroxyethyl or hydroxypropyl unit or, for example, N-hydroxyethylcyclohexyldiamine, N-hydroxyethylisophoronediamine, N-hydroxyethylpiperazine, bis(hydroxyethyl)toluenediamine. Particularly preferred amides are those described in EP 2511315 A1 and EP 1985642 A1 based on monoethanolamine (MEA) or diethanolamine (DEA), such as: Cocoamide DEA, Cocoamide MEA, Cocoamide MIPA, Sojaamide DEA, Undecenylamide DEA, Oleamide DEA, Oleamide MEA, Lauramide DEA, Lauramide MEA, PEG-5 Cocoamide, PEG-3 Oleoamide, PEG-6 Lauramide, ethoxylated isopropanolamide, reaction products of tall oil acid and diethylenetriamine (DETA) to the amide or imidazole. In another preferred embodiment, the Si-free surfactants are imidazoles. They can be prepared, for example, by reacting the carboxylic acids with (2-aminoethylamino)ethanol (AEEA). These are known as intermediates in the production of betaines or quats. Suitable imidazoles include, for example, the following compounds: 1-hydroxyethyl-2-heptadecenylimidazoline, 1-hydroxyethyl-2-nor-cocosalkylimidazoline, 1-hydroxyethyl-2-nor-laurylimidazoline, and 1-hydroxyethyl-2-heptylimidazoline. In another preferred embodiment, the Si-free surfactants are oxazolines. They can be prepared, for example, by reacting the carboxylic acids with amino alcohols. Suitable oxazolines include the following compounds: 2-(heptadecenyl)-2-oxazoline-4,4-dimethanol or 4-ethyl-2-(8-heptadecenyl)-2-oxazoline-4-methanol. In a further preferred embodiment, the Si-free surfactants are amidamines. Within the meaning of the invention, they belong to the aforementioned amides. They can be prepared, for example, by reacting the carboxylic acids with dimethylaminopropylamine (DMAPA) or with 2-(2-aminoethylamino)ethanol (AEEA). Amidamines based on DMAPA are common intermediates in the production of betaines or quats (quaternary ammonium compounds) that are suitable as Si-free surfactants. Suitable amidamines include, for example, castor oil amidamine, coconut fatty acid amidamine, stearyl acid amidamine, behenic acid amidamine, lauric acid amidamine, especially those amidamines based on 3-dimethylaminopropylamine or 2-(2-aminoethylamino)ethanol. In a further preferred embodiment, the Si-free surfactants are alcohol alkoxylates. Processes for preparing alcohol alkoxylates are known to those skilled in the art. The alcohol alkoxylates are preferably obtained by reacting alcohols with alkylene oxides. The Si-free surfactant is therefore preferably an alcohol alkoxylate, preparable by reacting alcohols with alkylene oxides. The alkylene oxides add to the alcohol, resulting in ring opening. The alcohols can be linear or branched, saturated or unsaturated, aliphatic or aromatic, cyclic or acyclic. The alcohols can also contain one or more hydroxyl groups. The alkylene oxides, in turn, are preferably selected from the group consisting of ethylene oxide (EO), propylene oxide (PO), butylene oxide (BO), and styrene oxide (SO). The alkylene oxides can be added individually in pure form, alternately one after the other in any desired dosing sequence, or simultaneously mixed.This determines the sequence of the oxyalkylene units or alkyleneoxy units as repeating units in the resulting polyether chain. The process can be used to construct polyether chains that are characterized by the fact that they can be produced in a targeted and reproducible manner with regard to structural composition and molecular weight. The sequence of repeating units can be varied within wide limits by changing the order in which the alkylene oxides are added. It is particularly preferred to react alcohols having 4 to 36 carbon atoms with alkylene oxide units selected from the group consisting of ethylene oxide (EO), propylene oxide (PO), butylene oxide (BO), and styrene oxide (SO) to produce the alcohol alkoxylates, with an average of 3 to 150 alkylene oxide units per hydroxyl group of the alcohol.Suitable alkoxylates include, for example: PPG-14 butyl ether, PPG-3 myristyl ether, PPG-15 stearyl ether, PEG-40 hydrogenated castor oil, isoceteth-20, laureth-4, steareth-2, PEG-6 capyl / capric glycerides, C9 alcohol ethoxylates, lauryl alcohol alkoxylate, tridecyl alcohol ethoxylates with 6 to 36 EO, mono-, di-, tri-styrylphenol ethoxylates, alkylphenol ethoxylates. Suitable alcohol alkoxylates are also known, for example, under the names Tomadol® (Evonik) or Nonidet® (Shell Chemical Co.). Suitable alcohol alkoxylates containing BO or SO are described, for example, in DE 19940797 A1. Suitable alcohol alkoxylates based on diols as starters are also known. The diol can be used directly as a starter or can be formed indirectly from the reaction of water as a starter with an alkylene oxide.These alcohol alkoxylates preferably have a block-like arrangement of the oxyalkylene units and are known, for example, under the names Pluronics® (BASF) or Vorasurf® (Dow Chemical Company). These are, for example, (OH-terminated) block copolymers of EO and PO. These compounds are also called poloxamers and have a triblock structure (EO-PO-EO). Vorasurf® 504, for example, is an (OH-terminated) block copolymer of EO and BO, as described, for example, in EP 0734404 A1. In a further preferred embodiment, the Si-free surfactants are alkoxylated amines. Processes for preparing alkoxylated amines are known to those skilled in the art. The alkoxylated amines are preferably obtained by reacting amines with alkylene oxides. The alkylene oxides add to the amine, resulting in ring opening. The amines can be linear or branched, aliphatic or aromatic, cyclic or acyclic. The amines can also contain one or more amino groups. The amino groups are preferably primary and / or secondary amino groups. The amines preferably have 4 to 36 carbon atoms. Talcamine and coconut amine are particularly preferred. The alkylene oxides, in turn, are preferably selected from the group consisting of ethylene oxide (EO), propylene oxide (PO), butylene oxide (BO), and styrene oxide (SO).The alkylene oxides can be added individually in pure form, alternately in any dosing sequence, or simultaneously mixed. This determines the sequence of the oxyalkylene units or alkyleneoxy units as repeating units in the resulting polyether chain. This process can be used to construct polyether chains that are characterized by the fact that they can be produced in a targeted and reproducible manner with regard to their structure and molecular weight. The sequence of the repeating units can be varied within wide limits by changing the order in which the alkylene oxides are added. Alkoxylated amines suitable as Si-free surfactants include, for example, ethoxylated talcamine and ethoxylated coconutamine, particularly those compounds obtained by reacting 2 to 15 mol of ethylene oxide with 1 mol of talcamine or coconutamine. In a further preferred embodiment, the Si-free surfactants are novolac-based surfactants as described in DE 3724716 C1 as foam stabilizer A in the examples. In a further preferred embodiment, the Si-free surfactants are compounds based on hydrogenated or partially hydrogenated, optionally alkoxylated ketone-aldehyde resins as described in EP 3320012 B1. Also suitable as Si-free surfactants are polymers based on N-vinylpyrrolidone and dibutyl maleate as described in US 3746663. Also suitable as Si-free surfactants are polymers of N-vinylpyrrolidone as described in DE 2244350 A1. Likewise, compounds based on polyamine or polyimine can be used as Si-free surfactants, as described, for example, in EP 3222650 A1. Further polymeric structures suitable as Si-free surfactants are described in EP 1790682 A1 and DE 102006042338 A1. EP 1790682 A1 describes the use of grafted polyether copolymers for stabilizing polyurethane foams, which are suitable as Si-free surfactants. DE 102006042338 A1 describes the use of polyethers containing urethane or urea groups for stabilizing polyurethane foams, which are also suitable as Si-free surfactants. EP 1790682 A1 and DE 102006042338 A1 disclose further Si-free foam stabilizers, which can also be used here as Si-free surfactants for stabilizing PU foams. In summary, the Si-free surfactant is preferably or comprises a carboxylic acid derivative selected from the group consisting of esters, amides, imides, imidazolines, and oxazolines, and / or a polyether compound. The polyether compound has at least 2, preferably 2 to 100, in particular 3 to 50 ether groups. Even more preferably, the Si-free surfactant is or comprises a carboxylic acid derivative selected from the group consisting of esters, amides, imides, imidazolines, and oxazolines, or an alcohol alkoxylate preparable by reacting alcohols with alkylene oxides. The carboxylic acid derivatives are thus, for example, carboxylic acid esters or carboxylic acid amides. The alcohol alkoxylates are preferably based on monools or diols, as described above. Si-free surfactant and the hydrocarbons (HCWs) can be used in any mass ratio. There are therefore no restrictions regarding the mass ratios. However, it is preferred that the hydrocarbons (HCWs) be used in combination with Si-free surfactant in a mass ratio of 1:4 to 1:200 in the composition according to the invention. The mass ratio represents the ratio of the total mass of all hydrocarbons (HCWs) to the total mass of all Si-free surfactants in the composition according to the invention. In addition to Si-free surfactants, Si-containing surfactants can also be used in principle. However, it is preferred that no Si-containing surfactants are used, and the composition according to the invention does not comprise Si-containing surfactants. In a particularly preferred embodiment of the invention, polyalkyl siloxanes (PAS) are additionally used, whereby mixtures or combinations of Hydrocarbons (KWS), polyalkyl siloxanes (PAS) and Si-free surfactants (SifS) can be used. It is therefore preferred that the composition according to the invention additionally comprises polyalkyl siloxanes (PAS). It is preferred that the polyalkylsiloxanes contain fewer than 20, more preferably fewer than 15, particularly preferably fewer than 11 Si atoms. It is also preferred that the polyalkylsiloxanes have at least 2 Si atoms. It is therefore preferred that the polyalkylsiloxanes contain fewer than 20, more preferably fewer than 15, particularly preferably fewer than 11 Si atoms, and each have at least 2 Si atoms. It is further preferred that the polyalkylsiloxanes are used in a mass ratio of 1:5 to 1:200 with respect to the Si-free surfactant. The mass ratio represents the ratio of the total mass of all polyalkylsiloxanes to the total mass of all Si-free surfactants in the composition according to the invention. In a preferred embodiment, the composition according to the invention additionally comprises polyalkyl siloxanes, wherein the polyalkyl siloxanes preferably contain less than 20, more preferably less than 15, particularly preferably less than 11 Si atoms, and wherein the polyalkyl siloxanes are preferably used in a mass ratio of 1:5 to 1:200 with respect to the Si-free surfactant. It is preferred that the mass fraction of the total amount of hydrocarbons KWS, Si-free surfactants and optional polyalkyl siloxanes based on 100 parts by mass of the polyol component is from 0.1 to 10 pphp, preferably from 0.5 to 5 pphp and particularly preferably from 1 to 3 pphp. According to a preferred embodiment of the invention, the polyalkylsiloxanes are subject to formula 1: M a D b T c Q d (Formula 1) with M = R 11 R 12 R 13 SiOi / 2 D = R 14 R 15 SiO2 / 2 T = R 16 SiO3 / 2 Q = SiO4 / 2 where R 11 , R 12 , R 13 , R 14 , R 15 , R 16 = identical or different hydrocarbon radicals having 1 to 12, preferably 1 to 8, carbon atoms, where the hydrocarbon radicals may be substituted with are substituted by heteroatoms, or H, particularly preferred are the radicals: phenyl-, CH3-, CH3CH2-, CH2CH- CICH2CH2CH2- and H-, and where a = 2 to 6 b = 0 to 8 c = 0 to 4 d = 0 to 2 with the proviso that a + b + c + d is < 20, preferably < 15, particularly preferably < 11. Preferably c + d is > 0.5. Particularly preferred is c + d >= 1. Preferably, d = 0 and c > 0.5. Particularly preferably, d = 0 and c greater than or equal to 1. Preferably, c + d < 0.5. Particularly preferably, c + d < 0.1. In a further preferred embodiment, R 16 different from R 11 , R 12 , R 13 , R 14 and R 15 . In a further preferred embodiment, R 11 , R 12 , R 13 different, so that the M unit in the siloxane carries two or three different residues. Preferred polyalkyl siloxanes satisfy the formula 2: Formula 2, with R 11 to R 16 and b, c, d as above. Preferred polyalkylsiloxanes of formula 2 satisfy formulas 3 or 4: Formula 4, with b, c, d as given above. Preferred polyalkyl siloxanes are the following: or or or, or or or oder The hydrocarbons KWS, Si-free surfactants and optional polyalkyl siloxanes (PAS) usable according to the invention can also be used as part of compositions with various carrier media. Suitable carrier media include, for example, glycols, alkoxylates, or oils of synthetic and / or natural origin. It corresponds to a preferred embodiment of the invention if the total mass fraction of hydrocarbons KWS, Si-free surfactants (SifS) and optional polyalkyl siloxanes (PAS) in the finished polyurethane foam is from 0.01 to 10 wt.%, preferably from 0.1 to 3 wt.%. The inventive combinations of hydrocarbons KWS, Si-free surfactants SifS and optional polyalkyl siloxanes are also referred to below as “mixture”, regardless of whether the components are added separately or together to the reaction mixture for producing the PU foam. As already explained, the composition according to the invention for producing polyurethane foam comprises at least one polyisocyanate component, one polyol component, optionally a catalyst which catalyzes the formation of a urethane or isocyanurate bond, optionally blowing agent, wherein the composition additionally comprises hydrocarbons KWS which have boiling points >100°C, preferably >150°C, at atmospheric pressure, and Si-free surfactant. The composition may comprise one or more polyisocyanate components, one or more polyol components, optionally one or more catalysts which catalyze the formation of a urethane or isocyanurate bond, and optionally one or more blowing agents, wherein the composition additionally comprises one or more hydrocarbons (KWS) which have boiling points >100°C, preferably >150°C, at atmospheric pressure, and one or more Si-free surfactants. The inventive mixture of hydrocarbons KWS, Si-free surfactants SifS and optional polyalkyl siloxanes has the advantage that they can be used to produce polyurethane or polyisocyanurate foams, in particular rigid foams, which are characterized by good fine cell structure and good insulating properties and at the same time have few foam defects. Preferred compositions according to the invention which are suitable for producing polyurethane or polyisocyanurate foams contain at least one polyisocyanate component, at least one polyol component, at least one foam stabilizer, at least one urethane and / or isocyanurate catalyst, blowing agent, and optionally at least one flame retardant and / or further additives, and are characterized in that at least one mixture according to the invention of hydrocarbons KWS, Si-free surfactants SifS and optional polyalkyl siloxanes is contained. A preferred composition according to the invention therefore contains the following components: (a) one or more polyol components (b) one or more polyisocyanate components (c) optionally one or more catalysts (d) a mixture of one or more hydrocarbons KWS, one or more Si-free surfactants SifS and optionally one or more polyalkyl siloxanes PAS (e) optionally one or more propellants (f) optionally one or more additives, preferably selected from the group consisting of fillers and flame retardants. A preferred composition according to the invention therefore comprises: (a) one or more polyol components (b) one or more polyisocyanate components (c) optionally one or more catalysts (d1) one or more hydrocarbons KWS (d2) one or more Si-free surfactants SifS (d3) optionally one or more polyalkyl siloxanes PAS (e) optionally one or more propellants (f) optionally one or more additives, preferably selected from the group consisting of fillers and flame retardants. In the composition according to the invention, the mass fraction of the mixture according to the invention (i.e. hydrocarbons KWS, Si-free surfactants SifS and optional polyalkylsiloxanes PAS) d) based on 100 parts by mass of polyol component a) is preferably from 0.1 to 10 pphp, more preferably from 0.5 to 5 pphp and particularly preferably from 1 to 3 pphp. As polyol component (a), one or more compounds with OH groups, SH groups, NH groups and / or NH2 groups, with a functionality of 1.8 to 8, are used. The polyol component comprises at least one compound with at least two isocyanate-reactive groups selected from OH groups, SH groups, NH groups and / or NH2 groups, in particular OH groups. A functionality of, for example, 1.8 can be achieved by mixing at least one compound with a higher functionality, for example, greater than or equal to 2, with at least one compound with a functionality of, for example, 1. This can occur in particular when a polyisocyanate component (b) with a functionality greater than 2 or additional crosslinkers are used as optional additives (f). Suitable compounds within the meaning of this invention are all organic substances with OH groups, SH groups, NH groups and / or NH2 groups, in particular OH groups, as well as mixtures thereof with a functionality of 1.8 to 8. Corresponding compounds that can usually be used in the production of PU foams are known to the person skilled in the art and are described, for example, in the "Kunststoffhandbuch, Band 7, Polyurethane", Carl Hanser Verlag, 3rd edition 1993, Chapter 3.1. Preferably, compounds with OH numbers in the range of 10 to 1200 mg KOH / g are used. The OH number is preferably determined either according to DIN EN ISO 4629-1:2016-12 (without catalyst) or according to DIN EN ISO 4629-2:2016-12 (with catalyst). It is preferred that the polyols or the polyol component have a number-average molecular weight of 500 to 15,000 g / mol. The number-average molecular weight can be determined, for example, by gel permeation chromatography (GPC), preferably according to DIN EN ISO 13885-1:2021-11 (THF as eluent), according to DIN EN ISO 13885-2:2021-11 (acrylamide as eluent), or according to ISO 13885-3:2020-07 (water as eluent), particularly preferably according to DIN EN ISO 13885-1:2021-11 (THF as eluent). The polyols or the polyol component preferably have a functionality of 1.8 to 8 and number-average molecular weights in the range of 500 to 15,000 g / mol. Preferably, the polyols used have OH numbers in the range of 10 to 1200 mg KOH / g, more preferably with OH numbers in the range of 30 to 800, even more preferably with OH numbers in the range of 50 to 600, in particular in the range of 80 to 500 mg KOH / g. Particularly preferred compounds are all polyether polyols and polyester polyols commonly used for the production of polyurethane systems, in particular polyurethane foams. In addition, polyether polycarbonate polyols, natural oil-based polyols (NOPs; e.g. described in WO 2005 / 033167, US 2006 / 0293400, WO 2006 / 094227, WO 2004 / 096882, US 2002 / 0103091, WO 2006 / 116456, EP 1678232), filler polyols, prepolymer-based polyols and / or recycling polyols can be used. Recycling polyols are polyols obtained from the chemical recycling of polyurethanes, for example, by solvolysis, such as glycolysis, hydrolysis, acidolysis, or aminolysis. The use of recycling polyols represents a particularly preferred embodiment of the invention. Polyether polyols can be prepared by known processes, for example by anionic polymerization of alkylene oxides in the presence of alkali hydroxides, alkali alkoxides or amines as catalysts and with the addition of at least one starter molecule which preferably contains 2 or 3 reactive hydrogen atoms or by cationic polymerization of Alkylene oxides in the presence of Lewis acids such as antimony pentachloride or boron trifluoride etherate, or by double metal cyanide catalysis. Suitable alkylene oxides contain 2 to 4 carbon atoms in the alkylene radical. Examples are tetrahydrofuran, 1,3-propylene oxide, 1,2- or 2,3-butylene oxide; ethylene oxide and 1,2-propylene oxide are preferably used. The alkylene oxides can be used individually, cumulatively, blockwise, alternating one after the other, or as mixtures. Compounds having at least 2, preferably 2 to 8 hydroxyl groups or having at least two primary amino groups in the molecule are used as starting molecules. Starter molecules that can be used include water, 2-, 3- or 4-hydric alcohols such as ethylene glycol, propanediol-1,2 and -1,3, diethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, castor oil, etc.Higher polyfunctional polyols, especially sugar compounds such as glucose, sorbitol, mannitol, and sucrose; polyhydric phenols; resoles, such as oligomeric condensation products of phenol and formaldehyde and Mannich condensates of phenols, formaldehyde, and dialkanolamines, as well as melamine; or amines such as aniline, EDA, TDA, MDA, and PMDA, particularly preferably TDA and PMDA. The choice of the appropriate starter molecule depends on the specific application of the resulting polyether polyol in polyurethane production. Polyester polyols are based on esters of polybasic aliphatic or aromatic carboxylic acids, preferably with 2 to 12 carbon atoms. Examples of aliphatic carboxylic acids are succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 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 condensing these polybasic carboxylic acids with polyhydric alcohols, preferably diols or triols with 2 to 12, particularly preferably with 2 to 6, carbon atoms, preferably trimethylolpropane and glycerol. In a particularly preferred embodiment, polyester polyols based on aromatic carboxylic acids are used in more than 50 pphp, preferably more than 70 pphp, based on 100 parts by mass of polyol component. It corresponds to a particularly preferred embodiment of the invention if polyester polyols with melting points below 30°C are used. In a further very particularly preferred embodiment, no polyols based on phenolic resins produced from novolaks and alkylene oxides, and no polyols based on aromatic amine polyols produced by alkoxylation of aromatic amines are used, which means that in this preferred embodiment less than 20 pphp, preferably less than 10 pphp, in particular less than 2 pphp, and most advantageously no polyols based on phenolic resins produced from novolaks and alkylene oxides, and at all no polyols based on aromatic amine polyols, produced by alkoxylation of aromatic amines, may be used. Polyether polycarbonate polyols are polyols that contain carbon dioxide bound as a carbonate. Since carbon dioxide is produced in large quantities as a by-product in many processes in the chemical industry, the use of carbon dioxide as a comonomer in alkylene oxide polymerizations is of particular commercial interest. Partially replacing alkylene oxides in polyols with carbon dioxide has the potential to significantly reduce polyol production costs. Furthermore, the use of CO2 as a comonomer is ecologically very advantageous, as this reaction represents the conversion of a greenhouse gas into a polymer. The production of polyether polycarbonate polyols by the addition of alkylene oxides and carbon dioxide to H-functional starter substances using catalysts has long been known.Various catalyst systems can be used for this purpose: The first generation consisted of heterogeneous zinc or aluminum salts, as described, for example, in US-A 3900424 or US-A 3953383. Furthermore, mono- and binuclear metal complexes have been successfully used for the copolymerization of CO2 and alkylene oxides (WO 2010 / 028362, WO 2009 / 130470, WO 2013 / 022932, or WO 2011 / 163133). The most important class of catalyst systems for the copolymerization of carbon dioxide and alkylene oxides are double metal cyanide catalysts, also known as DMC catalysts (US-A 4500704, WO 2008 / 058913). Suitable alkylene oxides and H-functional starter substances are those that are also used for the production of carbonate-free polyether polyols - as described above. Polyols based on renewable raw materials, "natural oil-based polyols" (NOPs), for the production of polyurethane foams are of increasing interest in view of the long-term limited availability of fossil resources, namely oil, coal, and gas, and against the backdrop of rising crude oil prices, and have already been described numerous times in such applications (WO 2005 / 033167; US 2006 / 0293400, WO 2006 / 094227, WO 2004 / 096882, US 2002 / 0103091, WO 2006 / 116456, and EP 1678232). A number of these polyols 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 properties are produced.Essentially, two groups can be distinguished: a) polyols based on renewable raw materials that are modified to such an extent that they can be used 100% for the production of polyurethanes (WO 2004 / 020497, US 2006 / 0229375); b) polyols based on renewable raw materials that, due to their processing and properties, can only replace the petrochemically based polyol to a certain extent (W02009 / 058367). Another class of usable polyols are the so-called filler polyols (polymer polyols). These are characterized by the fact that they contain solid organic fillers up to a solids content of 40% or more in a dispersed distribution. Suitable polyols include SAN, PHD, and PIPA polyols. SAN polyols are highly reactive polyols containing a dispersed styrene / acrylonitrile (SAN) copolymer. PHD polyols are highly reactive polyols containing polyurea in dispersed form. PIPA polyols are highly reactive polyols containing a dispersed polyurethane, formed, for example, by the in situ reaction of an isocyanate with an alkanolamine in a conventional polyol. Another class of usable polyols are those obtained as prepolymers by reacting polyol with isocyanate in a molar ratio of preferably 100:1 to 5:1, preferably 50:1 to 10:1. Such prepolymers are preferably prepared dissolved in polymer, with the polyol preferably corresponding to the polyol used to prepare the prepolymers. As polyisocyanate component (b), one or more polyisocyanates with two or more isocyanate groups are generally used. Suitable polyisocyanates for the purposes of this invention are all organic isocyanates with two or more isocyanate groups, in particular the known aliphatic, cycloaliphatic, arylaliphatic, and preferably aromatic polyfunctional isocyanates. Examples include alkylene diisocyanates having 4 to 12 carbon atoms in the alkylene radical, such as 1,12-dodecane diisocyanate, 2-ethyltetramethylene-1,4-diisocyanate, 2-methylpentamethylene-1,5-diisocyanate, tetramethylene-1,4-diisocyanate, pentamethylene diisocyanate (PDI) and preferably hexamethylene-1,6-diisocyanate (HMDI), cycloaliphatic diisocyanates such as cyclohexane-1,3- and -1,4-diisocyanate and the corresponding isomer mixtures, 4,4'-methylenedicyclohexyl diisocyanate (H12MDI), isophorone diisocyanate (IPDI), 2,4- and 2,6-methylcyclohexyl diisocyanate and the corresponding isomer mixtures and preferably aromatic di- and polyisocyanates such as 2,4- and 2,6-toluene diisocyanate (TDI) as well as the corresponding isomer mixtures, naphthylene diisocyanate, diethyltoluene diisocyanate, 4,4'- or 2,2'- or 2,4'-diphenylmethane diisocyanate (MDI) and polymethylene polyphenyl polyisocyanates (PMDI, “polymeric MDI”).The organic polyisocyanates can be used individually or as mixtures. Corresponding "oligomers" of diisocyanates can also be used, such as the IPDI trimer based on isocyanurate, biuret, or urethdione. Furthermore, the use of prepolymers based on the above-mentioned isocyanates is possible. Particularly suitable is the mixture known as "polymeric MDI" (also called "crude MDI"), consisting of MDI and more highly condensed analogues with an average functionality of 2 to 4, as well as the various isomers of TDI in pure form or as isomer mixtures. It is also possible to use isocyanates modified by the incorporation of urethane, uretdione, isocyanurate, allophanate, and other groups, so-called modified isocyanates. Examples of particularly suitable isocyanates are also given in EP 1712578, EP 1161474, WO 00 / 58383, US. 2007 / 0072951 , EP 1678232 and WO 2005 / 085310, which are incorporated herein by reference. A preferred ratio of polyisocyanate component (b) and polyol component (a), expressed as an index of the formulation, ie as a stoichiometric ratio of isocyanate groups to isocyanate-reactive groups (e.g. OH groups, NH groups) multiplied by 100, is in the range from 10 to 1000, preferably 40 to 700, more preferably from 150 to 550, particularly preferably from 200 to 500. An index of 100 represents a molar ratio of the reactive groups of 1 to 1. In a preferred embodiment of the invention, the index of the formulation is in the range 150 to 550, particularly preferably 200 to 500. This means that, in a preferred embodiment, there is a significant excess of isocyanate groups to isocyanate-reactive groups. This leads to trimerization reactions of the isocyanates, which thus form isocyanurates. These foam types are also referred to as polyisocyanurate (PIR) foams and are characterized by improved fire behavior, i.e., poorer burning. These foam types are a preferred subject of the invention. Particularly preferably, one or more polyester polyols are included as polyol component (a). Suitable catalysts (c) for the production of polyurethanes, especially PU foams, are known to the person skilled in the art. For the purposes of the present invention, all compounds capable of catalyzing the reaction of isocyanate groups with OH, NH, or other isocyanate-reactive groups, as well as the reaction of isocyanate groups with one another, can be used. The usual catalysts known from the prior art can be used, including, for example, amines (cyclic or acyclic; monoamines, diamines, oligomers with one or more amino groups), ammonium compounds, organometallic compounds, and / or metal salts, preferably of tin, iron, bismuth, potassium, and / or zinc. In particular, mixtures of several such compounds can be used as catalysts. As component (d), the mixtures according to the invention (i.e. hydrocarbons KWS, Si-free surfactants SifS and optional polyalkyl siloxanes PAS) are used. According to a further preferred embodiment, the total amount of the mixture used (i.e. the total of all hydrocarbons KWS, Si-free surfactants and optional polyalkyl siloxanes) is such that the mass fraction based on the finished polyurethane is 0.01 to 10 wt.%, preferably 0.1 to 3 wt.%. Blowing agents and their use in the production of PU foams are known to those skilled in the art. The use of one or a combination of several blowing agents depends fundamentally on the type of foaming process used, the type of system, and the application of the resulting PU foam. Chemical and / or physical blowing agents, or a combination of both, can be used. Depending on the amount of blowing agent used, a foam with a high or low density is produced. Thus, foams with densities of 5 to 900 kg / m 3 , preferably 5 to 350 kg / m 3 , particularly preferably 8 to 200 kg / m 3 , especially 8 to 150 kg / m 3 be manufactured. All corresponding compounds with suitable boiling points and mixtures thereof, such as hydrocarbons with 3, 4 or 5 carbon atoms, preferably cyclo-, iso-, n-pentane, fluorocarbons (HFC), preferably HFC 245fa, HFC 134a or HFC 365mfc, chlorofluorocarbons (HCFC), preferably HCFC 141b, hydrofluoroolefins (HFO) or hydrohaloolefins, preferably 1234ze, 1234yf, 1224yd, 1233zd(E) or 1336mzz, esters, preferably methyl formate, ketones, preferably acetone, ethers preferably dimethoxymethane, or chlorinated hydrocarbons, preferably dichloromethane or 1,2-dichloroethane, can be used as physical blowing agents. It corresponds to a particularly preferred embodiment of the invention if hydrocarbons having 3, 4 or 5 carbon atoms, preferably having 4 or 5 carbon atoms, in particular having 5 carbon atoms, are used, wherein preferably no halogenated blowing agents are used. All compounds that react with NCO groups to release gases, such as water or formic acid, or that release gases due to the temperature increase during the reaction, such as sodium bicarbonate, can be used as chemical blowing agents. A particularly preferred embodiment of the invention is when the composition according to the invention contains water in combination with hydrocarbons having 5 carbon atoms, HFO, hydrohaloolefins or HFC, or mixtures thereof, as blowing agent. A very particularly preferred embodiment of the invention is when only water in combination with hydrocarbons having 5 carbon atoms is used as blowing agent. Suitable water contents for the purposes of this invention depend on whether or not one or more blowing agents are used in addition to the water. For purely water-blown foams, preferred values ​​are typically 1 to 20 pphp. If other blowing agents are also used, the preferred amount is usually reduced to 0.1 to 5 pphp. As additives (f) it is possible to use all substances known in the art which are used in the production of polyurethanes, in particular polyurethane foams, such as crosslinkers and chain extenders, stabilizers against oxidative degradation (so-called antioxidants), flame retardants, surfactants, biocides, cell-refining additives, cell openers, solid fillers, antistatic additives, nucleating agents, thickeners, dyes, pigments, color pastes, fragrances, emulsifiers, etc. As flame retardants, the composition according to the invention can contain all known flame retardants suitable for the production of PU foams, such as, for example, halogen-containing or halogen-free organic phosphorus-containing compounds, such as, for example, triethyl phosphate (TEP), tris(1-chloro-2-propyl) phosphate (TCPP, also known as tris(2-chloroisopropyl) phosphate), tris(2-chloroethyl) phosphate (TCEP), dimethyl methanephosphonate (DMMP), dimethylpropanephosphonate (DMPP), ammonium polyphosphate or red phosphorus, nitrogen-containing compounds such as, for example, melamine, melamine cyanurate or melamine polyphosphate or halogenated compounds such as, for example, chlorinated and / or brominated polyether and / or polyester polyols. Mixtures of different flame retardants can also be used. The flame retardants are preferably liquid flame retardants. Another object of the invention is a process for producing polyurethane foam by reacting one or more polyol components with one or more polyisocyanate components, characterized in that the reaction takes place in the presence of hydrocarbons KWS, Si-free surfactant and optionally polyalkyl siloxanes, in particular using the composition according to the invention. A further subject of the invention is therefore a process for producing polyurethane foam by reacting one or more polyol components with one or more polyisocyanate components, characterized in that the reaction takes place in the presence of one or more hydrocarbons KWS, one or more Si-free surfactants and optionally one or more polyalkyl siloxanes, in particular using the composition according to the invention. It is preferred that the components hydrocarbons KWS, Si-free surfactant and optional polyalkyl siloxanes are added separately or together to the reaction mixture for producing the polyurethane foam. The inventive process for producing PU foams can be carried out by all known methods, e.g., by hand mixing or, preferably, using foaming machines. If the process is carried out using foaming machines, high-pressure or low-pressure machines can be used. The inventive process can be carried out both batchwise and continuously, and 1K, 1.5K, or 2K systems, as described in EP 3717538 A1, US 7776934 B2, EP 1400547 B1, or EP 2780384 B2, can be used. A preferred polyurethane or polyisocyanurate foam formulation in the sense of this invention results in a density of 5 to 900 kg / m3 and has the composition stated in Table 1. Table 1: Composition of a preferred polyurethane or polyisocyanurate foam formulation For further preferred embodiments and configurations of the process according to the invention, reference is also made to the statements made above in connection with the composition according to the invention. These statements apply preferably. Another object of the invention is a polyurethane foam obtainable by the said process. According to a preferred embodiment of the invention, the polyurethane foam has a density of 5 to 900 kg / m 3 , preferably 8 to 800 kg / m 3 , more preferably 10 to 600 kg / m 3 , especially 30 to 150 kg / m 3 on. The polyurethane foam (PU foam) according to the invention is preferably a rigid polyurethane foam (PU rigid foam). “Polyurethane rigid foam” or “PU rigid foam” is a well-established technical term. The known and fundamental difference between flexible foam and rigid foam is that flexible foam exhibits elastic behavior and thus the deformation is reversible. Rigid foam, on the other hand, is permanently deformed. In the context of the present invention, rigid polyurethane foam is understood in particular to mean a foam according to DIN 7726, which has a compressive strength according to DIN 53 421 / DIN EN ISO 604 of advantageously ≥ 20 kPa, preferably ≥ 80 kPa, preferably ≥ 100 kPa, more preferably ≥ 150 kPa, particularly preferably ≥ 180 kPa. Preferably, the rigid polyurethane foam according to DIN ISO 4590 advantageously has a closed cell content of greater than 50%, preferably greater than 80% and Particularly preferred is greater than 90%. Further information on rigid polyurethane foams can be found in "Kunststoffhandbuch, Volume 7, Polyurethane," Carl Hanser Verlag, 3rd edition 1993, Chapter 6. The PU foams, especially PU rigid foams, can be used as or for the production of insulating materials, preferably insulation boards, refrigerators, insulating foams, roof liners, packaging foams or spray foams. A further subject of the present invention is therefore the use of polyurethane or polyisocyanurate foams according to the invention as insulating panels and / or insulation materials, preferably for cooling equipment. The cooling equipment preferably comprises the polyurethane or polyisocyanurate foam according to the invention as the insulating material. The PU foams according to the invention can be used advantageously, particularly in the cold storage, refrigeration equipment and household appliance industries; e.g., for the production of insulation panels for roofs and walls, as insulation material in containers and warehouses for frozen goods, as well as for refrigerators and freezers. Other preferred fields of application are in vehicle construction, in particular for the production of vehicle headliners, body parts, interior trim, refrigerated vehicles, large containers, transport pallets, packaging laminates, in the furniture industry, e.g. for furniture parts, doors, trim, in electronic applications. Cooling apparatuses according to the invention have a PU foam (polyurethane or polyisocyanurate foam) according to the invention as insulating material. A further object of the invention is the use of PU foam as insulation material in refrigeration technology, in refrigerated furniture, in the construction, automotive, shipbuilding and / or electronics sectors, as insulation panels, as spray foam, as one-component foam. The subject matters according to the invention are described below by way of example, without the invention being limited to these exemplary embodiments. If ranges, general formulas or classes of compounds are given below, these are intended to include not only the corresponding ranges or groups of compounds that are explicitly mentioned, but also all sub-ranges and sub-groups of compounds that can be obtained by removing individual values ​​(ranges) or compounds. If documents are cited within the scope of the present description, their content, in particular with regard to the facts in the context of which the document was cited, is intended to be fully included in the disclosure of the present invention. Percentages are, if Unless otherwise stated, these are percentages by weight. Mean values ​​given below are weight averages unless otherwise stated. If parameters determined by measurement are given below, the measurements were carried out at a temperature of 25 °C and a pressure of 101,325 Pa, unless otherwise stated. In the examples listed below, the present invention is described by way of example, without the invention, the scope of which emerges from the entire description and the claims, being intended to be limited to the embodiments mentioned in the examples. ,EXAMPLES: The following materials were used as Si-free surfactants (SifS). SifS No.1: Diethanolamide based on soybean oil and diethanolamine, prepared as described in DE 102011007479 A1 in Example 1 b as Amide 2. SifS No. 2: Imidazole based on N-(2-aminoethyl)ethanolamine and coconut fatty acid as described in US 2267965 Example 3. SifS No. 3: Sorbitan monolaurate, commercially available as TEGO SML from Evonik. SifS No. 4: Novolak-based surfactant as described in DE 3724716 C1 as foam stabilizer A. SifS No. 5: Ethoxylate of a hydrogenated ketone-aldehyde resin as described in EP 3320012 B1 as OHV-3. The following materials were used as hydrocarbons (HCs). KWS-A: Oxo oil based on hydroformylation products of dodecene as used in the production of iso- C 13 -alcohols occur as by-products and appear as a low-boiling fraction, so-called Light Oxo Fraction, commercially available as Oxo Oil LS 13 from Evonik. KWS-B: Tetrabutene, which was produced as an oligomer based on butene as described in DE102008007081 A1, commercially available as Tetrabutene from Evonik. The following material was used as polyalkyl siloxane (PAS): PAS-A: Trisiloxane with octyl side chain according to formula 1 , M a D b T c Q d , as defined above with a=2; b=1 ; c=0; d=0; R 11 =Methyl; R 12 =Methyl; R 13 =Methyl; R 14 =Octyl, R 15 =Methyl; as described in WO 2020 / 144003 A1 as PAS No. 5. For the production of PU rigid foams according to the invention, the Si-free surfactants were used in mixture or combination with the various hydrocarbons and the polyalkyl siloxane. The following mixtures were used, which are summarized in Table 2. Table 2: Description of SifS / KWS mixtures (overview of SifS / KWS combinations) In foaming tests, foams containing one of the above-mentioned mixtures of Si-free surfactant, hydrocarbon KWS and, if necessary, polyalkyl siloxane PAS were compared with compositions containing only the corresponding Si-free surfactant instead of the above-mentioned mixture, with regard to their properties: SifS No. 1 is compared with mixtures 1 , 6 and 9 . SifS No. 2 is compared with mixtures 2, 7 and 10. SifS No. 3 is compared with mixtures 3, 8 and 11 . SifS No. 4 is compared with Mixture 4. SifS No. 5 is compared with mixtures 5 and 12 . The following raw materials were used to produce foams: Stepanpol PS 2412: Polyester polyol from Stepan TCPP: Tris(2-chloroisopropyl)phosphate from Fyrol (flame retardant) POLYCAT 5, from Evonik Operations GmbH, amine-based catalyst Kosmos 75 from Evonik Operations GmbH, catalyst based on potassium octoate Polycat 5 from Evonik Operations GmbH, amine catalyst MDI (44V20): Desmodur 44V20L from Covestro, diphenylmethane-4,4'-diisocyanate (MDI) with isomers and higher functional homologues. Production of PU foams: The foaming was carried out using a manual mixing method. All components according to Table 3, with the exception of the polyisocyanate (MDI), were weighed into a beaker and mixed with a 6 cm diameter plate stirrer for 30 seconds at 1000 rpm. The amount of blowing agent evaporated during the mixing process was determined by reweighing and then replenished. The polyisocyanate (MDI) was then added, and the reaction mixture was stirred with the described stirrer for 5 seconds at 3000 rpm. In the case of the PIR (polyisocyanurate) formulations used here for panel applications such as building insulation, the mixture was immediately poured into an aluminum mold measuring 50 cm x 25 cm x 7 cm, thermostatted at 65°C. The foam formulation was added in a quantity sufficient to fill the mold to a minimum. The foams were demolded after 10 minutes and then stored at room temperature for 24 hours. Using a cross-sectional view of the foam, the degree of internal disturbances and pore structure were visually assessed using a scale of 1 to 10, with 10 representing an undisturbed foam and 1 representing an extremely disturbed foam. The thermal conductivity (A-value in mW / mK) was measured on 2.5 cm thick panes using a Hesto Lambda Control device, model HLC X206, after one day (1 d) and after 7 days (7 d) at an average temperature of 10°C in accordance with the specifications of the standard EN 12667:2001-05. Table 3 summarizes the foam formulations used. Table 3 (data in parts by weight) The results of the foaming tests with the mixtures of SifS, KWS and, if applicable, PAS compared to SifS alone are summarized in Table 4. Panels were manufactured as described above and the lambda values ​​(in mW / m K) were measured after 1 day and 7 days, and the internal disturbances were rated on a scale of 1-10. Table 4: Results of the foaming tests From the experiments it is clearly evident that the mixtures according to the invention consisting of hydrocarbon KWS, Si-free surfactant SifS and optionally polyalkyl siloxane PAS lead to improved insulation properties compared to SifS alone. It is particularly important to note that even a very small addition of KWS and optionally PAS leads to measurable improvements.

Claims

Patent claims:

1. Composition for the production of polyurethane foam, comprising at least one polyisocyanate component, one polyol component, optionally a catalyst which catalyzes the formation of a urethane or isocyanurate bond, optionally a blowing agent, wherein the composition further comprises hydrocarbons (HCs) which have boiling points >100°C, preferably >150°C, at normal pressure, and Si-free surfactant.

2. Composition according to claim 1, characterized in that the hydrocarbons KWS have 10 to 24 carbon atoms, preferably selected from the group consisting of decene, dodecene, dodecane, isododecane, tetradecane, tributene, tributane, tetrabutene, tetrabutane, alkylbenzenes with at least 10 carbon atoms and oxo oils.

3. Composition according to claim 1 or 2, characterized in that the Si-free surfactant, at a concentration of 0.5 wt.% in water, reduces the static surface tension of this surfactant-water mixture at a temperature of 20 °C to less than 70 mN / m, preferably to less than 60 mN / m, more preferably to less than 60 mN / m, more preferably to less than 50 mN / m, and particularly preferably to less than 40 mN / m.

4. Composition according to one of claims 1 to 3, characterized in that the Si-free surfactant is or comprises a non-ionic surfactant.

5. Composition according to any one of claims 1 to 4, characterized in that the Si-free surfactant is or comprises a carboxylic acid derivative selected from the group consisting of esters, amides, imides, imidazolines and oxazolines, and / or a polyether compound.

6. Composition according to one of claims 1 to 5, characterized in that the hydrocarbons KWS are used in combination with Si-free surfactant in a mass ratio of 1 :5 to 1 :

200.

7. Composition according to any one of claims 1 to 6, characterized in that it additionally comprises polyalkyl siloxanes, wherein the polyalkyl siloxanes preferably contain less than 20, more preferably less than 15, and particularly preferably less than 11 Si atoms, and wherein the polyalkyl siloxanes are preferably used in a mass ratio of 1:4 to 1:200 with respect to the Si-free surfactant.

8. Composition according to one of claims 1 to 7, characterized in that the mass fraction of the total amount consists of hydrocarbons KWS, Si-free surfactant and optional polyalkyl siloxanes based on 100 parts by mass of polyol component from 0.1 to 10 pphp, preferably from 0.5 to 5 pphp and particularly preferably from 1 to 3 pphp.

9. Composition according to one of claims 7 or 8, characterized in that the polyalkyl siloxanes satisfy formula 1: M a D b T c Q d (Formula 1) with M = R 11 R 12 R 13 SiO 1 / 2 D = R 14 R 15 SiO 2 / 2 T = R 16 SiO 3 / 2 Q = SiO 4 / 2 where R 11 , R 12 , R 13 , R 14 , R 15 , R 16= identical or different hydrocarbon residues with 1 to 12, preferably 1 to 8, carbon atoms, wherein the hydrocarbon residues are optionally substituted with heteroatoms, or H, in particular preferably the residues are: phenyl-, CH3-, CH3CH2-, CH2CH- CICH2CH2CH2- and H-, and wherein a = 2 to 6 b = 0 to 8 c = 0 to 4 d = 0 to 2 with the proviso that a + b + c + d < 20, preferably < 15, in particular preferably < 11.

10. Composition according to claim 9, characterized in that R 16 different from R 11 , R 12 , R 13 , R 14 and R 15 is, and / or that R 11 , R 12 and R 13 are different.

11. A process for producing polyurethane foam by reacting one or more polyol components with one or more polyisocyanate components, characterized in that the reaction takes place in the presence of hydrocarbons, silicon-free surfactant and optionally polyalkyl siloxanes, in particular using a composition according to one of claims 1 to 10.

12. Method according to claim 11, characterized in that the components hydrocarbons KWS, Si-free surfactant and optional polyalkyl siloxanes are added separately or together to the reaction mixture for the production of the polyurethane foam. Use of a combination of hydrocarbons (HCs), silicon-free surfactant, and optional polyalkyl siloxanes for the production of polyurethane foams, preferably as a foam stabilizer, preferably for improving the insulating properties of the polyurethane foam, in particular using a composition according to any one of claims 1 to 10. Polyurethane foam obtainable by the method according to claim 11 or 12. Use of the polyurethane foam according to claim 14 as insulation boards and / or insulating material, preferably for cooling equipment.

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