Polyisocyanurate resin foam with high compressive strength, low thermal conductivity, and high surface quality

Abstract

The present invention relates to a method for producing rigid polyisocyanurate foams, in which (a) an aromatic polyisocyanate, (b) isocyanate-reactive compounds comprising at least one polyetherol (b1) and / or polyesterol (b2), wherein the number-average content of isocyanate-reactive hydrogen atoms of components (b1) and (b2) is at least 1.7, (c) a catalyst, (d) a blowing agent, (e) a flame retardant, (f) optional auxiliary substances and additives, and (g) an optional compound having an aliphatic hydrophobic group and not falling within the definition of compounds (a) to (f), are mixed to obtain a reaction mixture that can be cured to obtain rigid polyisocyanurate foams, wherein the blowing agent (d) has 2 to 5 carbon atoms, at least one The process comprises at least one aliphatic halogenated hydrocarbon compound (d1) consisting of hydrogen atoms and at least one fluorine and / or chlorine atom, wherein compound (d1) comprises a hydrocarbon compound (d2) having at least one carbon-carbon double bond and 4 to 8 carbon atoms, the molar proportion of halogenated hydrocarbon compound (d1) being 20 to 60 mol % and the molar proportion of hydrocarbon compound (d2) being 40 to 80 mol %, based in each case on the total content of blowing agents (d1) and (d2), components (b) to (f) having aliphatic hydrophobic groups, the content of said aliphatic hydrophobic groups being 4.0 mass % or less, based on the total content of components (b) to (g), and the mixing to obtain the reaction mixture is carried out at an isocyanate index of at least 240. The present invention further relates to rigid polyisocyanurate foams obtainable by the process according to the present invention.

Description

[Technical Field]

[0001] The present invention relates to a method for producing polyisocyanurate foam, wherein (a) an aromatic polyisocyanate, (b) an isocyanate-reactive compound (containing at least one polyetherol (b1) and / or polyesterol (b2)), where the number average content of isocyanate-reactive hydrogen atoms in components (b1) and (b2) is at least 1.7, (c) a catalyst, (d) a blowing agent, (e) a flame retardant, (f) optionally auxiliary substances and additives, and (g) optionally a compound having an aliphatic hydrophobic group and not falling under the definitions of compounds (a) to (f) are mixed to obtain a reaction mixture, which is then cured to obtain a rigid polyisocyanurate foam, wherein the blowing agent (d) contains 2 to 5 carbon atoms, at least one hydrogen atom and at least one fluorine atom and / or comprises at least one aliphatic halogenated hydrocarbon compound (d1) composed of chlorine atoms, wherein compound (d1) comprises a hydrocarbon compound (d2) having at least one carbon-carbon double bond and 4 to 8 carbon atoms, in each case, based on the total content of the blowing agents (d1) and (d2), the molar ratio of the halogenated hydrocarbon compound (d1) is between 20 and 60 mol%, and the molar ratio of the hydrocarbon compound (d2) is between 40 and 80 mol%, and components (b) to (f) may include compounds having aliphatic hydrophobic groups, the content of aliphatic hydrophobic groups is 4.0% by mass or less based on the total content of components (b) to (g), and the mixing to obtain the reaction mixture is carried out at an isocyanate index of at least 240. The present invention further relates to a rigid polyisocyanurate foam that can be obtained by the process according to the present invention. [Background technology]

[0002] Rigid polyurethane foam or rigid polyisocyanurate foam is commonly used as insulation for thermal purposes. This foam is particularly used in composite elements having at least one outer layer. The continuous operation double-beltline manufacturing of composite elements (often called sandwich elements) from a core of isocyanate-based foam (typically polyurethane (PUR) or polyisocyanurate (PIR) foam) and a metal outer layer is now carried out on a large scale. In addition to sandwich elements for insulation in cold storage warehouses, elements are becoming increasingly important as elements or roofing elements for a wide variety of building facades.

[0003] Essential requirements for polyurethane or polyisocyanurate foam are low thermal conductivity, good mechanical properties, and excellent flame retardancy. The thermal insulation properties of closed-cell rigid foam depend on many factors, particularly the average cell size and the thermal conductivity of the cell gas. In the manufacture of sandwich elements, it is ideal that the foam surface, especially the underside of the foam, is free of defects.

[0004] Chlorofluorocarbons (CFCs) were once widely used as physical blowing agents in the manufacture of polyisocyanate-based rigid foams, particularly due to their extremely low thermal conductivity. Their stratospheric ozone depletion potential (ODP) has long been known, and therefore the use of CFCs is no longer permitted under regulatory systems. Hydrochlorofluorocarbons (HCFCs), especially R141b, were initially seen as promising alternatives to CFCs, but this class of substances also has ozone-depleting properties, and their use has been banned. Similarly, alternative blowing agents with low thermal conductivity (e.g., hydrofluorocarbons (HFCs)) have virtually no ozone-depleting effect, but are generally powerful greenhouse gases and therefore have high GWPs (Global Warming Potential). Consequently, using HFCs as physical blowing agents in the manufacture of polyurethane or polyisocyanurate foams is also undesirable.

[0005] Due to the aforementioned drawbacks of CFCs and HFCs, hydrocarbons are now frequently used as physical blowing agents for the production of polyisocyanate-based rigid foams. Pentane isomers, which are very commonly used as physical blowing agents in the continuous and discontinuous production of rigid foam composite elements, are of central importance here. In the continuous production of polyurethane or polyisocyanurate sandwich elements, the use of n-pentane as a physical blowing agent has been established over time, particularly for economic reasons.

[0006] To achieve improved processability of polyurethane or polyisocyanurate reaction mixtures combined with hydrocarbons, polyol components obtained by incorporating hydrophobic compounds into the polyol structure have been developed. For example, Patent Document 1 (EP2804886) describes the incorporation of fatty acid structures into polyester polyols. Thus, it is possible to use, for example, pure fatty acids or fatty acid derivatives (e.g., vegetable oils) as reactants in the production of polyester or polyether polyols. The fatty acid derivatives are incorporated into the resulting polyester polyol by trans-esterification during polycondensation. Another option for hydrophobizing polyester polyols is, for example, the use of dimeric fatty acids as units for polyester synthesis (Patent Document 2 (EP3140333)) or the use of hydrophobic alkyl alcohols, such as nonylphenol, or fatty alcohols and their derivatives. Patent Document 3 (EP2820059) describes the production of such polyetherols by using the proportion of fatty acids or fatty acid derivatives in the starter components used for alkoxylation. In addition to incorporating hydrophobic structures in polyols, improved processability of hydrocarbon-blown polyurethane or polyisocyanurate-containing reaction mixtures can also be achieved by directly using hydrophobic compounds such as vegetable oils, fatty acids, fatty acid derivatives, or fatty alcohols in the polyol component. For example, Patent Document 4 (EP1023351) describes the use of hydrophobic compound additives such as carboxylic acids (especially fatty acids), carboxylic acid esters (especially fatty acid esters), and alkyl alcohols (especially fatty alcohols) in polyol resin mixtures for producing polyurethane or polyisocyanurate-containing rigid foams. Patent Document 5 (EP3294786) describes the use of, for example, alkoxylated vegetable oils in polyol resin mixtures for producing rigid foams. Patent Document 6 (EP0742241) describes the use of hydrophobic compatibilizers, such as nonylphenol, to improve the processability of hydrocarbon-blown polyol components.

[0007] Replacing n-pentane with the physical blowing agent cyclopentane allows for the production of rigid foams with low thermal conductivity from reaction mixtures of polyurethane or polyisocyanate, but the change to cyclopentane significantly reduces the mechanical properties of the foam, particularly its compressive strength and dimensional stability.

[0008] The conversion from non-flammable CFCs and HFCs to flammable hydrocarbons requires a significant increase in the amount of flame retardant in the reaction components to achieve equivalent flame retardancy in rigid foams. Increasing the amount of flame retardant added is undesirable for environmental toxicological reasons. Compared directly to CFCs and HFCs, hydrocarbons also have significantly higher thermal conductivity, which is another reason why using hydrocarbons alone as physical blowing agents to produce rigid foams with improved thermal insulation properties is equally undesirable.

[0009] Non-flammable hydrofluoroolefins (HFOs), such as hydrofluoropropene or hydrochlorofluoropropene, are suitable alternatives to HFCs due to their very low ODP and GWP and low thermal conductivity. Their use in reaction mixtures for producing closed-cell rigid polyurethane or polyisocyanurate foam is described in numerous patent publications. These include the following specifications: Patent Document 7 (EP2154223), Patent Document 8 (EP2739676), Patent Document 9 (EP2513023), Patent Document 10 (US20180264303), Patent Document 11 (US9738768), Patent Document 12 (US2013 / 0149452), and Patent Document 13 (US20150322225).

[0010] Among HFO blowing agent compounds, 1-chloro-3,3,3-trifluoropropene [1233zd(E)] and 1,1,1,4,4,4-hexafluoro-2-butene [1336mzz(Z)] have gained commercial importance in recent years. One drawback of these blowing agents is that they significantly reduce the storage stability of polyol components when stored together with certain amine catalysts and silicone-containing foam stabilizers. In the production of continuous sandwich elements, the storage stability problem can be overcome, for example, by metering and supplying amine catalysts, foam stabilizers, or HFO blowing agents to the reaction mixture as separate components; further options for improving storage stability include the use of specific catalysts and specific foam stabilizers.

[0011] In addition to its storage stability drawbacks, the use of 1-chloro-3,3,3-trifluoropropene, as with cyclopentane, has been shown to reduce the compressive strength of the foam. The use of excessive amounts of 1,1,1,4,4,4-hexafluoro-2-butene often results in a decrease in the quality of the foam beneath the outer layer, especially in continuous double-belt processes.

[0012] Patent document 14 (WO2019096763) describes a polyurethane foam sandwich element for thermal insulation and a method for manufacturing the sandwich element. The blowing agent for manufacturing the polyurethane foam includes cis-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz-Z) and cyclopentane. The polyurethane foam composite panel according to the present invention has good thermal insulation performance and mechanical strength. Isocyanurate foams, particularly foams with an isocyanate index greater than 220, are not disclosed.

[0013] Examples 1 and 2 of Patent Document 15 (WO2018218102) describe rigid polyurethane foam produced using potassium octate (Dabco® K15), a flame retardant (TMCP), and HFO-1336mzz(Z) (cis-1,1,1,4,4,4-hexafluoro-2-butene) and cyclopentane in a molar ratio of 50:50 or 25:75. The polyol used is Stepanpol PS 2352, a hydrophobic polyesterol containing 7% by mass of fatty acids and 2.5% by mass of nonylphenol.

[0014] Polyisocyanurate foam is also known to have higher fire resistance than polyurethane foam.

[0015] Patent document 16 (WO2016184433) describes the production of a polyurethane foam in Sample 3 of Example 2 using potassium octate, a flame retardant, and a mixture of HCFO-1233zd and cyclopentane in a molar ratio of approximately 35:65. The polyol used is GR835G, a sugar-based polyetherol from Sinopec with an OH value of 450 mgKOH / g. As a result, the isocyanate index is 210. [Prior art documents] [Patent Documents]

[0016] [Patent Document 1] EP2804886 [Patent Document 2] EP3140333 [Patent Document 3] EP2820059 [Patent Document 4] EP1023351 [Patent Document 5] EP3294786 [Patent Document 6] EP0742241 [Patent Document 7] EP2154223 [Patent Document 8] EP2739676 [Patent Document 9] EP2513023 [Patent Document 10] US20180264303 [Patent Document 11] US9738768 [Patent Document 12] US2013 / 0149452 [Patent Document 13] US20150322225 [Patent Document 14] WO2019096763 [Patent Document 15] WO2018218102 [Patent Document 16] WO2016184433 [Summary of the Invention] [Problems to be Solved by the Invention]

[0017] Therefore, an object of the present invention is to improve the profile of the above characteristics, and in particular, it can be used in the production of rigid polyisocyanurate foams, has high flame retardancy and significantly reduced thermal conductivity, and shows very excellent mechanical compression strength despite the improved heat insulation characteristics. The object is to develop a new method that enables the production of an optimized rigid foam. A further object of the present invention is to be particularly suitable for producing polyisocyanurate sandwich elements in a continuous manufacturing process, and to provide a method for providing sandwich elements having a very low thermal conductivity, high compression strength and high flame retardancy, and particularly excellent foam surface quality facing the lower outer layer.

[0018] This objective is achieved by a method for producing rigid polyisocyanurate foam, in which a reaction mixture is obtained by mixing (a) an aromatic polyisocyanate, (b) an isocyanate-reactive compound (containing at least one polyetherol (b1) and / or polyesterol (b2)), where the number average content of isocyanate-reactive hydrogen atoms in components (b1) and (b2) is at least 1.7, (c) a catalyst, (d) a blowing agent, (e) a flame retardant, (f) optionally auxiliary substances and additives, and (g) optionally a compound having an aliphatic hydrophobic group and not falling under the definition of compounds (a) to (f), and the mixture is cured to obtain rigid polyisocyanurate foam, where the blowing agent (d) has 2 to 5 carbon atoms, at least one hydrogen atom and at least one fluorine atom The present invention further relates to a rigid polyisocyanurate foam that can be obtained by the process according to the present invention. [Means for solving the problem]

[0019] Rigid polyisocyanurate foam is generally understood to mean a foam containing both urethane groups and isocyanurate groups. In the context of this invention, the term rigid polyurethane foam should be understood to also include rigid polyisocyanurate foam, and the production of polyisocyanurate foam is based on an isocyanate index of at least 180. The isocyanate index should be understood to mean the ratio of isocyanate groups to isocyanate-reactive groups multiplied by 100. An isocyanate index of 100 corresponds to the equimolar ratio of the isocyanate groups used in component (a) to the isocyanate-reactive groups in components (b) to (g).

[0020] The rigid polyisocyanurate film according to the present invention exhibits a compressive stress of 80 kPa or more, preferably 120 kPa or more, and particularly preferably 140 kPa or more, at 10% compression. Furthermore, the isocyanate-based rigid foam has a closed-cell content of more than 80%, preferably more than 90%, according to DIN ISO 4590. Further details regarding the rigid polyisocyanurate foam according to the present invention can be found in "Kunststoffhandbuch, Vol. 7, Polyurethane", Carl Hanser Verlag, 3rd edition 1993, Chapter 6, particularly Chapters 6.2.2 and 6.5.2.2.

[0021] It is essential for the present invention that components (b) to (g) contain aliphatic hydrophobic groups in an amount of 0% to less than 4% by mass, i.e., 0 to 4% by mass, preferably 0 to 3.5% by mass, and particularly 0.1 to 3.0% by mass, based on the total mass of components (b) to (g). In the context of the present invention, a hydrophobic group should be understood to mean an aliphatic hydrocarbon group having more than 6, more preferably more than 8, and less than 100, particularly at least 10, and at most 50 directly adjacent carbon atoms. The adjacent carbon atoms may be connected by carbon-carbon double bonds as well as carbon-carbon single bonds. The carbon atoms of the hydrophobic group are directly bonded to each other and are not interrupted, for example, by heteroatoms. In contrast, the hydrogen atoms of the hydrocarbon may be substituted, for example, by halogen atoms, OH groups, or carboxylic acid groups. The hydrocarbon of the hydrophobic group according to the present invention is preferably unsubstituted.

[0022] When using compounds containing hydrophobic groups, they may be part of any of the compounds (b) to (f), or they may be used as another compound (g) containing hydrophobic groups. To calculate the proportion of hydrophobic groups, only the mass of the hydrophobic groups is used, and any substituents other than hydrogen, such as OH groups or halogen groups, are not considered in the proportion calculation.

[0023] Polyisocyanate (a) is an aromatic polyfunctional isocyanate known in the art. Such polyfunctional isocyanates are known and can be produced by known methods. Polyfunctional isocyanates can also be used in the form of a mixture, in which case component (A) comprises different polyfunctional isocyanates. Polyisocyanate (a) is a polyfunctional isocyanate having two (hereinafter also called diisocyanate) or more than two isocyanate groups per molecule.

[0024] The isocyanate (a) is selected from the group consisting of aromatic polyisocyanates, such as 2,4- and 2,6-toluene diisocyanates and corresponding isomer mixtures, 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanates and corresponding isomer mixtures, mixtures of 4,4'- and 2,4'-diphenylmethane diisocyanates, polyphenyl polymethylene polyisocyanates, mixtures of 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanates and polyphenyl polyethylene polyisocyanates (crude MDI), and mixtures of crude MDI and toluene diisocyanate.

[0025] Particularly preferred are 2,2'-, 2,4'-, or 4,4'-diphenylmethane diisocyanate (MDI) and mixtures of two or three of these isomers, 1,5-naphthylene diisocyanate (NDI), 2,4- and / or 2,6-toluene diisocyanate (TDI), 3,3'-dimethyldiphenyl diisocyanate, 1,2-diphenylethane diisocyanate and / or p-phenylene diisocyanate (PPDI).

[0026] Modified polyisocyanates, i.e., products obtained by the chemical reaction of organic polyisocyanates and containing at least two reactive isocyanate groups per molecule, are also frequently used. In particular, polyisocyanates containing esters, ureas, biuretes, allophanates, carbodiimides, isocyanurates, uretdiones, carbamates and / or urethane groups are mentioned, often together with unconverted polyisocyanates.

[0027] The polyisocyanate of component (a) is particularly preferably 2,2'-MDI, 2,4'-MDI, or 4,4'-MDI, or a mixture of at least two of these isocyanates (also known as monomeric diphenylmethane or MMDI), or oligomeric MDI consisting of at least three aromatic nuclei and higher homologs of MDI having at least three functional values, or a mixture of two or more of the above diphenylmethane diisocyanates, or crude MDI obtained in the production of MDI, or preferably a mixture of at least one oligomer of MDI and at least one of the above low molecular weight MDI derivatives 2,2'-MDI, 2,4'-MDI, or 4,4'-MDI (also known as polymeric MDI). Isomers and homologs of MDI are generally obtained by distillation of crude MDI.

[0028] In addition to dinuclear MDIs (MMDIs), polymeric MDIs also include one or more polynuclear condensation products of MDIs having more than two, particularly three, four, or five, functional groups. Polymeric MDIs are known and are often called polyphenylpolymethylene polyisocyanates.

[0029] The average functional value of polyisocyanates containing polymer MDI can vary in the range of approximately 2.2 to approximately 4, particularly 2.4 to 3.8, and especially 2.6 to 3.0. Such mixtures of MDI-based polyfunctional isocyanates with different functional values ​​are particularly crude MDI obtained as an intermediate product in the production of MDI.

[0030] Polyfunctional isocyanates or mixtures of two or more polyfunctional isocyanates based on MDI are known and are commercially available from BASF Polyurethanes GmbH under the trade names Lupranat® M20, Lupranat® M50, or Lupranat® M70.

[0031] Component (a) preferably contains at least 70% by mass, particularly preferably at least 90% by mass, and especially 100% by mass, of one or more isocyanates selected from the group consisting of oligomers of 2,2'-MDI, 2,4'-MDI, 4,4'-MDI, and MDI, based on the total mass of component (a). The content of oligomer MDI is preferably at least 20% by mass, particularly preferably more than 30% by mass and less than 80% by mass, based on the total mass of component (a).

[0032] The viscosity of component (a) used may vary over a wide range. Component (a) is preferably 100 to 3000 mPa at 25°C. * s, particularly preferably 100-1000 mPa * s, particularly preferably 100-800 mPa * s, particularly preferably 200-700 mPa * s, and especially preferably 400-650 mPa * It has a viscosity of s. The viscosity of component (a) may vary over a wide range.

[0033] The isocyanate-reactive compound (b) used may be any compound having an isocyanate-reactive group known in polyurethane chemistry, preferably a compound having at least one hydroxyl group, -NH group, NH2 group, or carboxylic acid group, preferably at least one NH2 or OH group, and particularly a compound having at least one OH group. The number of functional groups relative to the isocyanate group may be in the range of 1 to 8, preferably 2 to 8. Examples of isocyanate-reactive compounds include polyether polyols (b1), polyester polyols (b2), or mixtures thereof, preferably polyesterols (b2) or mixtures of polyetherols (b1) and polyesterols (b2). Polyetherols (b1) and polyesterols (b2) preferably have a number-average molecular weight of 150 to 15000 g / mol, preferably 150 to 5000 g / mol, and particularly preferably 200 to 2000 g / mol. In addition to polyetherols and polyesterols, low molecular weight chain extenders and / or crosslinking agents known in polyurethane chemistry may also be used. Compound (b) preferably has a number-average molecular weight of 62 to 15000 g / mol. Compound (b) preferably has a number-average functional value of at least 1.7, and more preferably at least 2. According to the present invention, polyetherol (b1) and / or polyesterol (b2) have a number-average functional value of at least 1.7, more preferably at least 2.0.

[0034] Polyetherols (b1) are prepared, for example, from epoxides such as propylene oxide and / or ethylene oxide, or from tetrahydrofuran and active hydrogen starter compounds, such as aliphatic alcohols, phenols, amines, carboxylic acids, water, and compounds based on natural substances such as sucrose, sorbitol, or mannitol. These may include basic catalysts or bimetallic cyanide catalysts, such as those described in PCT / EP2005 / 010124, EP90444, or WO05 / 090440.

[0035] Polyesterols (b2) are preferably produced in the presence of an esterification catalyst from, for example, aliphatic or aromatic dicarboxylic acids and polyhydric alcohols, polythioether polyols, polyesteramides, hydroxyl-containing polyacetals and / or hydroxyl-containing aliphatic polycarbonates. Further possible polyols are cited, for example, in "Kunststoffhandbuch, Band 7, Polyurethane," Carl Hanser Verlag, 3rd edition 1993, Chapter 3.1.

[0036] According to the present invention, the isocyanate-reactive compound (b) comprises a polyether polyol (b1) and / or a polyester polyol (b2), preferably polyester polyol (b2), optionally in combination with polyether polyol (b1). In either case, based on the total mass of polyether polyol (b1) and polyester polyol (b2), the mass fraction of polyether polyol (b1) is preferably 0 to 30% by mass, particularly preferably 0 to 20% by mass, and particularly 1 to 15% by mass, and the mass fraction of polyester polyol (b2) is preferably 70 to 100% by mass, particularly preferably 80 to 100% by mass, and particularly 85 to 99% by mass. In the context of this disclosure, the terms "polyester polyol" and "polyester polyol" are synonymous, as are the terms "polyether polyol" and "polyether polyol".

[0037] Polyetherol (b1) is obtained by anionic polymerization of alkylene oxide by known methods, for example, by adding at least one starter molecule containing 1 to 8, preferably 2 to 6, reactive hydrogen atoms in bonded form, or a mixture of starter molecules containing an average of 1.5 to 8, preferably 2 to 6, reactive hydrogen atoms in bonded form from all present starters, in the presence of a catalyst. Fractional functionalities can be obtained by using a mixture of starter molecules having different functionalities. Nominal functionality ignores the influence of side reactions, for example. Usable catalysts include alkali metal hydroxides such as sodium hydroxide or potassium hydroxide, or alkali metal alkoxides such as sodium methoxide, sodium or potassium ethoxide, or potassium isopropoxide, or, in the case of cationic polymerization, Lewis acids such as antimony pentachloride, boron trifluoride etherate, or Fuller's earth. Amine alkoxylation catalysts, such as dimethylethanolamine (DMEOA), imidazole, and imidazole derivatives, can also be used. Other usable catalysts include so-called DMC catalysts and other complex metal cyanide compounds.

[0038] The alkylene oxide used is preferably one or more compounds having 2 to 4 carbon atoms in the alkylene radical, such as tetrahydrofuran, 1,2-propylene oxide, ethylene oxide, or 1,2- or 2,3-butylene oxide, each in the form of a single compound or a mixture. It is preferable to use ethylene oxide and / or 1,2-propylene oxide, and particularly preferable to use ethylene oxide.

[0039] Possible starter molecules include hydroxyl or amine-containing compounds, such as sugar derivatives like ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, bisphenol A, bisphenol F, glycerol, trimethylolpropane, pentaerythritol, and sucrose; hexitol derivatives like sorbitol; methylamine, ethylamine, isopropylamine, butylamine, benzylamine, aniline, toluidine, and toluenediamine (TDA). Examples include naphthylamine, ethylenediamine, methylenedianiline, 2,2'-diaminodiphenylmethane (2,2-MDA), 2,4'-diaminodiphenylmethane (2,4-MDA), 4,4'-diaminodiphenylmethane (4,4-MDA), diethylenetriamine, 4,4'-methylenedianiline, 1,3-propanediamine, 1,6-hexanediamine, ethanolamine, diethanolamine, triethanolamine, and other dihydric or polyhydric alcohols, monofunctional or polyfunctional amines, or water. Highly functional compounds are often in solid form under conventional reaction conditions for alkoxylation, and therefore are generally carried out with a co-initiator. Examples of co-initiators include water, lower polyhydric alcohols such as glycerol, trimethylolpropane, pentaerythritol, diethylene glycol, ethylene glycol, propylene glycol, and their homologues. Possible further co-initiators include, for example, organic fatty acids or monofunctional fatty alcohols, fatty acid monoesters or fatty acid methyl esters, such as oleic acid, stearic acid, methyl oleate, methyl stearate, or biodiesel, which play a role in improving the solubility of the blowing agent during the manufacture of rigid polyurethane foam.

[0040] Preferred starter molecules for the production of polyether polyol (b1) include sorbitol, sucrose, ethylenediamine, TDA, trimethylolpropane, pentaerythritol, glycerol, biodiesel, nonylphenol, ethylene glycol, and diethylene glycol. More preferred starter molecules include all starters or starter mixtures having an average overall functionality of 3 or less, particularly glycerol, trimethylolpropane, biodiesel, nonylphenol, ethylene glycol, diethylene glycol, propylene glycol, and bisphenol A, especially ethylene glycol, diethylene glycol, and glycerol.

[0041] The polyether polyol used in the context of component (b1) preferably has an average functionality of 1.5 to 6, particularly 2.0 to 4.0, and a number-average molecular weight of preferably 150 to 3000 g / mol, particularly preferably 150 to 1500 g / mol, particularly 250 to 800 g / mol. The OH value of the polyether polyol of component (b1) is preferably 1200 to 50 mg KOH / g, preferably 600 to 100 mg KOH / g, particularly 300 to 150 mg KOH / g.

[0042] A suitable polyester polyol (b2) can be produced from a mixture of an organic dicarboxylic acid having 2 to 12 carbon atoms, preferably aromatic, or aromatic and aliphatic dicarboxylic acid, and a polyhydric alcohol having 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms, preferably a diol.

[0043] The dicarboxylic acids used may include, in particular: succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, and terephthalic acid. Dicarboxylic acids may be used here alone or in mixtures. Instead of free dicarboxylic acids, corresponding dicarboxylic acid derivatives, such as dicarboxylic acid esters or dicarboxylic acid anhydrides of alcohols having 1 to 4 carbon atoms, may also be used. The aromatic dicarboxylic acids or acid derivatives used preferably include phthalic acid, phthalic anhydride, terephthalic acid, and / or isophthalic acid, either in mixtures or alone. The aliphatic dicarboxylic acids used are preferably a mixture of succinic acid, glutaric acid, and adipic acid in a mass ratio of, for example, 20-35:35-50:20-32, and particularly adipic acid. The polyesterol (b2) used is particularly preferably obtained using only aromatic dicarboxylic acids or their derivatives. Preferably used aromatic dicarboxylic acids are at least one compound selected from the group consisting of terephthalic acid, dimethyl terephthalate (DMT), polyethylene terephthalate (PET), phthalic acid, phthalic anhydride (PSA), and isophthalic acid, and particularly preferably at least one compound from the group consisting of terephthalic acid, dimethyl terephthalate (DMT), polyethylene terephthalate (PET), and phthalic anhydride (PSA), and especially from the group consisting of phthalic acid and / or phthalic anhydride.

[0044] Examples of dihydric and polyhydric alcohols, particularly diols, include: monoethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,2- or 1,3-propanediol, dipropylene glycol, polypropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol, glycerol, trimethylolpropane, and pentaerythritol, as well as alkoxylates of the same starters. It is preferable to use monoethylene glycol, diethylene glycol, triethylene glycol, 1,2- or 1,3-propanediol, dipropylene glycol, and ethoxylates of the same starters, such as ethoxylated glycerol, or a mixture of at least one of the aforementioned diols. Particularly preferred are mixtures of monoethylene glycol, diethylene glycol, glycerol, and ethoxylates of the same starters, or at least two of the aforementioned diols, particularly diethylene glycol. It is also possible to use polyester polyols derived from lactones, such as ε-caprolactone, or hydroxycarboxylic acids, such as ω-hydroxycaproic acid.

[0045] The production of polyester polyols (b2) may include polycondensation of aliphatic and aromatic polycarboxylic acids and / or derivatives with polyhydric alcohols in the absence of a catalyst or preferably in the presence of an esterification catalyst, advantageously under an atmosphere of an inert gas such as nitrogen in the molten material, at a temperature of 150°C to 280°C, preferably 180°C to 260°C, optionally under reduced pressure, until a desirable acid value is reached, advantageously less than 10, but preferably less than 2. Suitable esterification catalysts are metals, metal oxides, or metal salts, such as iron, cadmium, cobalt, lead, zinc, antimony, magnesium, titanium, and tin. However, polycondensation may also be carried out in the liquid phase in the presence of a diluent and / or co-diluting agent, such as benzene, toluene, xylene, or chlorobenzene, for azeotropic removal by distillation of condensation water.

[0046] To produce polyester polyol (b2), an organic polycarboxylic acid and / or derivative and a polyhydric alcohol are polycondensed in a molar ratio of advantageously 1:1 to 2.2, preferably 1:1.05 to 2.1, and particularly preferably 1:1.1 to 2.0.

[0047] The resulting polyester polyol (b2) generally has a number average molecular weight of 200 to 3000, preferably 300 to 1000, and particularly 400 to 800.

[0048] If component (b) contains a compound having hydrophobic groups, the compound contains not only at least one hydrophobic group but also at least one isocyanate-reactive group (e.g., an acid group, an amino group, or a hydroxyl group). These components may be polyetherols (b1) or polyesterols (b2), but alternatively or additionally, other compounds containing both one or more isocyanate-reactive groups and one or more hydrophobic groups may be used. If the hydrophobic groups are components of polyetherols (b1) or polyesterols (b2), they can be incorporated into polyols (b1) or (b2) by known reactions such as transesterification or alkoxylation. Starting compounds having hydrophobic groups to be incorporated into polyols (b1) or (b2) generally have at least one group that can be esterified, transesterified, or alkoxylated, such as a carboxylic acid group, a carboxylic acid ester group, a carboxamide group, a carboxylic acid anhydride group, a hydroxyl group, or a primary or secondary amino group.

[0049] Compounds having a hydrophobic group in component (b) that do not fall under the definition of polyetherol (b1) or polyesterol (b2) are, for example, alkyl alcohols, aliphatic alcohols, or hydroxyl-functional hydrophobic substances such as hydroxyl-functional oleochemical compounds. Examples of such alkyl alcohols and aliphatic alcohols include octyl, nonyl, decyl, undecyl, dodecyl, oleyl, cetyl, isodecyl, tridecyl, lauryl and mixed C12-C14 alcohols, 2-ethylhexanol, alkylphenols having more than six carbon atoms in the alkyl radical, such as nonylphenol, oxo alcohols having more than six carbon atoms obtained by hydroformylation of α-olefins and further reactions, Guerbet alcohols having more than six carbon atoms and mixtures of different alkyl and aliphatic alcohols.

[0050] When using hydrophobic hydroxyl functional compounds, it is preferable to use the following: castor oil, belladonna oil, hydroxyl-modified oils such as grapeseed oil, black cumin oil, pumpkin seed oil, borage seed oil, soybean oil, wheat germ oil, rapeseed oil, sunflower oil, peanut oil, apricot kernel oil, pistachio kernel oil, almond oil, olive oil, macadamia nut oil, avocado oil, sea buckthorn oil, sesame oil, hazelnut oil, evening primrose oil, wild rose oil, hemp oil, safflower oil, walnut oil, fatty acid esters modified with hydroxyl groups and based on myristoleic acid, palmitoleic acid, oleic acid, vaccenic acid, petroseric acid, gadoleic acid, erucic acid, nervonic acid, linoleic acid, linolenic acid, stearidonic acid, arachidonic acid, thymnodonic acid, crupanodonic acid, or cervonic acid, or a mixture of at least two of these compounds.

[0051] Further groups in hydroxyl-functional oleochemicals can be obtained by ring-opening of epoxidized fatty acid esters through simultaneous reaction with alcohols and optionally subsequent further transesterification. The introduction of hydroxyl groups into oleochemicals is mainly achieved by epoxidation of olefin double bonds contained in these products, followed by the reaction of the formed epoxy group with a monohydric or polyhydric alcohol. Here, the epoxide ring becomes a hydroxyl group, or in the case of a polyfunctional alcohol, a structure with more OH groups. Since oleochemicals are typically glycerol esters, transesterification is carried out in parallel with the above reaction. The resulting compounds preferably have a molecular weight in the range of 500 to 1500 g / mol.

[0052] The hydrophobic compound (b) containing an amine group should be understood to mean a compound having preferably between 7 and 40 carbon atoms. Examples include aliphatic alkanolamines such as decylamine, dodecylamine, tetradecylamine, and hexadecylamine.

[0053] Suitable alkanolamides include, for example, fatty acid alkanolamides, such as fatty acid diethanolamide, lauric acid diethanolamide, and oleic acid monoethanolamide.

[0054] As described, the hydrophobic group-containing compound (b) can also be understood to mean a compound having at least one carboxylic acid group, for example, a monofunctional or bifunctional carboxylic acid having 7 to 40 carbon atoms per molecule. Examples include: dimeric fatty acids or preferably fatty acids. Examples of fatty acids are caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, ricinoleic acid, and mixtures thereof. The acid may be of biological or petrochemical origin. An example of a suitable petrochemical acid is, for example, 2-ethylhexanoic acid.

[0055] If present, the oily chemical compound having a hydroxyl functional group is more preferably a hydrophobic polyesterol (b2a). The production of the hydrophobic polyester polyol (b2a) preferably involves using a fatty acid, a fatty acid derivative, or an alkylphenol alkoxylate having eight or more carbon atoms in the alkyl group as the hydrophobic starting compound.

[0056] The polyester polyol (b2) is preferably, in all cases, based on the total amount of components (b2a1) to (b2a4), (b2a1) A dicarboxylic acid composition containing 10-80 mol%, the dicarboxylic acid composition containing the following, (b2a11) Based on the dicarboxylic acid composition, 20 to 100 mol% of one or more aromatic dicarboxylic acids or their derivatives, (b2a12) Based on the dicarboxylic acid composition, 0 to 80 mol% of one or more aliphatic dicarboxylic acids or their derivatives, (b2a2) 0-30 mol% of one or more fatty acids and / or fatty acid derivatives, (b2a3) 2-70 mol% of one or more aliphatic or alicyclic diols having 2-18 carbon atoms, or alkoxylates thereof, (b2a4) 0-80 mol% of an alkoxylated product of at least one starter molecule having at least two average functional groups, The mixture contains at least one polyester ol (b2a) that can be obtained by esterification, where the total amount of components (b2a1) to (b2a4) is 100 mol%.

[0057] The polyester polyol of component (b2) preferably has 1.7 or more number-average functional groups, preferably 1.8 or more, particularly preferably 2.0 or more, and especially 2.2 or more. As a result, the crosslinking density of the polyurethane produced using it becomes higher, and therefore the mechanical properties of the polyurethane foam become better.

[0058] Component (b) may further contain chain extenders and / or crosslinkers to modify, for example, mechanical properties, such as hardness. The chain extenders and / or crosslinkers used are diols and / or triols, and amino alcohols having a molecular weight of less than 150 g / mol, preferably 60 to 130 g / mol. Possible compounds include, for example, aliphatic, alicyclic and / or aromatic aliphatic diols having 2 to 8, preferably 2 to 6 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, diethylene glycol, dipropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, o-, m-, p-dihydroxycyclohexane, and bis(2-hydroxyethyl)hinokine. Similarly, aliphatic and alicyclic triols such as glycerol, trimethylolpropane, and 1,2,4- and 1,3,5-trihydroxycyclohexane are also possible.

[0059] When chain extenders, crosslinkers, or mixtures thereof are used for the manufacture of rigid polyurethane foam, they are advantageously used in amounts of 0% to 15% by mass, preferably 0% to 5% by mass, based on the total mass of component (b). Component (b) preferably contains less than 10% by mass, particularly preferably less than 7% by mass, and especially less than 5% by mass of chain extenders and / or crosslinkers.

[0060] In particular, the compounds used as catalysts (c) for the manufacture of polyurethane foam include compounds that significantly accelerate the reaction between the reactive hydroxyl group compounds of components (b) to (g) and polyisocyanate (a).

[0061] Basic polyurethane catalysts, such as tertiary amines, such as triethylamine, tributylamine, dimethylbenzylamine, dicyclohexylmethylamine, dimethylcyclohexylamine, N,N,N',N'-tetramethyldiaminodiethyl ether, bis(dimethylaminopropyl)urea, N-methyl- or N-ethylmorpholine, N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N,N-tetramethylbutanediamine, N,N,N,N-tetramethylhexane-1,6-diamine, pentamethyldiethylenetriamine, bis(2-dimethylaminoethyl) ether, dimethylpiperazine It is advantageous to use N-dimethylaminoethylpiperidine, 1,2-dimethylimidazole, 1-azabicyclo[2.2.0]octane, 1,4-diazabicyclo[2.2.2]octane (Dabco), and alkanolamine compounds, such as triethanolamine, triisopropanolamine, N-methyl- and N-ethyldiethanolamine, dimethylaminoethanol, 2-(N,N-dimethylaminoethoxy)ethanol, N,N',N''-tris(dialkylaminoalkyl)hexahydrazine, such as N,N',N''-tris(dimethylaminopropyl)-s-hexahydrotriazine, and triethylenediamine. However, suitable catalysts include metal salts, such as iron(II) chloride, zinc chloride, lead octoate, and tin salts, such as tin dioctoate, tin diethylhexoate, and dibutyltin dilaurate, as well as mixtures of tertiary amines and organotin salts.

[0062] Possible catalysts also include: amidines, e.g., 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine; tetraalkylammonium hydroxides, e.g., tetramethylammonium hydroxide; alkali metal hydroxides, e.g., sodium hydroxide; and alkali metal alcoholates, e.g., sodium methanelate and sodium isopropanolate; alkali metal carboxylates; and alkali metal salts of long-chain fatty acids having 8 to 20 carbon atoms and optionally pendant OH groups.

[0063] Other catalysts that can be incorporated include amines, preferably amines having OH, NH, or NH2 functional groups, such as ethylenediamine, triethanolamine, diethanolamine, ethanolamine, and dimethylethanolamine. The incorporated catalyst can be considered as a compound of component (c) or a compound of component (b).

[0064] It is preferable to use 0.001 to 10 parts by mass of catalyst or a combination of catalysts based on 100 parts by mass of component (b). The reaction can also be carried out without catalyst. In this case, the catalytic activity of the amine-initiated polyol is usually utilized.

[0065] Possible catalysts for the trimerization reaction of excess NCO groups include: catalysts that form isocyanurate groups, for example, ammonium ions or alkali metal salts, particularly ammonium carboxylates or alkali metal carboxylates, either alone or in combination with tertiary amines. The formation of isocyanurates yields flame-retardant PIR foams, which are preferably used in rigid foams for technical applications, such as thermal insulation sheets or sandwich elements in the construction industry.

[0066] In preferred embodiments, catalyst (c) comprises an amine catalyst having a tertiary amino group and an ammonium or alkali metal carboxylate catalyst. In particularly preferred embodiments, catalyst (c) comprises at least one amine catalyst selected from the group consisting of pentamethyldiethylenetriamine and bis(2-dimethylaminoethyl) ether and at least one alkali metal carboxylate catalyst selected from the group consisting of potassium formate, potassium acetate and potassium 2-ethylhexanoate. Surprisingly, the use of these catalysts in the continuous production of sandwich elements, for example in double belts, has been found to enable sandwich elements having a particularly smooth foam surface facing the outer layer, especially facing the lower outer layer. As a result, sandwich panels with excellent adhesion of the foam to the outer layer and a defect-free surface are obtained.

[0067] According to the present invention, the foaming agent (d) used is a foaming agent mixture comprising at least one aliphatic halogenated hydrocarbon compound (d1) composed of 2 to 5 carbon atoms, at least 1 hydrogen atom, and at least 1 fluorine and / or chlorine atom, and a hydrocarbon compound (d2) having 4 to 8 carbon atoms, wherein compound (d1) has at least one carbon-carbon double bond.

[0068] Suitable compounds (d1) include trifluoropropene and tetrafluoropropene, e.g., (HFO-1234), pentafluoropropene, e.g., (HFO-1225), chlorotrifluoropropene, e.g., (HFO-1233), chlorotetrafluoropropene, and hexafluorobutene, and mixtures of one or more of these components. Tetrafluoropropene, pentafluoropropene, chlorotrifluoropropene, and hexafluorobutene are preferred, and the unsaturated terminal carbon atoms have at least one chlorine or fluorine substituent. Examples include 1,3,3,3-tetrafluoropropene (HFO-1234ze); 1,1,3,3-tetrafluoropropene; 1,2,3,3,3-pentafluoropropene (HFO-1225ye); 1,1,1-trifluoropropene; 1,1,1,3,3-pentafluoropropene (HFO-1225zc); 1,1,2,3,3-pentafluoropropene (HFO-1225yc); 1-chloro-2,3,3,3-tetrafluoropropene (HFO-1224yd); 1,1,1,2,3-pentafluoropropene (HFO-1225yez); 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd); 1,1,1,4,4,4-hexafluorobuto-2-ene (HFO-1336mzz) or mixtures of two or more of these components.

[0069] Particularly preferred compounds (d1) are trans-1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(E)), cis-1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd), trans-1,1,1,4,4,4-hexafluorobuta-2-ene (HFO-1336mzz(E)), cis-1,1,1,4,4,4-hexafluorobuta-2-ene (HFO-1336mzz(Z)), or mixtures of two or more of these components. Particularly preferred is trans-1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(E)), which, surprisingly, results in a foam quality with virtually no defects in the lower outer layer during the continuous production process.

[0070] Examples of hydrocarbon compounds (d2) having 4 to 8 carbon atoms include compounds such as heptane, hexane, and isopentane, preferably industrial mixtures such as n- and isopentane, n- and isobutane, and propane, cycloalkanes such as cyclopentane and / or cyclohexane, especially pentane isomers, such as n-pentane, isopentene, and cyclopentane. Hydrocarbon compounds (d2) preferably contain at least 60 mol%, particularly preferably more than 70 mol%, and especially more than 80 mol%, of alicyclic hydrocarbon compounds.

[0071] In addition to the blowing agents (d1) and (d2), further physical blowing agents may be used. Suitable such agents include liquids that are inert to the isocyanate used, have a boiling point below 100°C at atmospheric pressure, preferably below 50°C, and evaporate when subjected to an exothermic polyaddition reaction. Examples include ethers, e.g., furan, dimethyl ether, and diethyl ether; ketones, e.g., acetone and methyl ethyl ketone; alkyl carboxylates, e.g., methyl formate, dimethyl oxalate, and ethyl acetate; halogenated hydrocarbons, e.g., methylene chloride, dichloromonofluoromethane, difluoromethane, trifluoromethane, difluoroethane, tetrafluoroethane, chlorodifluoroethane, 1,1-dichloro-2,2,2-trifluoroethane, 2,2-dichloro-2-fluoroethane, and heptafluoropropane. Mixtures of these low-boiling point liquids and / or mixtures with other substituted or unsubstituted hydrocarbons may also be used. The proportion of physical blowing agents that do not fall under the definition of component (d1) or (d2) is preferably less than 30% by mass, particularly preferably less than 15% by mass, and more preferably less than 5% by mass, based on the total mass of the blowing agent components (d1) and (d2) and the further physical blowing agents, respectively. This is especially true when no further physical blowing agents are used in addition to the blowing agent components (d1) and (d2).

[0072] The blowing agents used to produce polyurethane foam according to the present invention also include chemical blowing agents. These react with isocyanate groups to produce carbon dioxide, and in the case of formic acid, carbon dioxide and carbon monoxide are produced. A preferred chemical blowing agent (d3) further comprises an organic carboxylic acid, such as formic acid, acetic acid, oxalic acid, and a further carboxyl-containing compound having fewer than six carbon atoms, and water.

[0073] In addition to compound (d1), it is preferable not to use halogenated hydrocarbons as a blowing agent. The chemical blowing agent (d3) used is preferably water, a formic acid-water mixture, or formic acid, and a particularly preferred chemical blowing agent is water or a formic acid-water mixture, especially a water-formic acid mixture having a formic acid content of more than 70% by mass based on the blowing agent (d3), which results in improved outer layer adhesion and a defect-free foam surface beneath the lower outer layer.

[0074] When using a chemical blowing agent (d3), it is preferably used in an amount of less than 2% by mass, and more preferably 0.5 to 1.5% by mass, based on the total mass of components (b) to (g).

[0075] According to the present invention, the molar ratio of halogenated hydrocarbon compound (d1) is 20 to 60 mol%, preferably 25 to 55 mol%, and particularly preferably 30 to 50 mol%, and the molar ratio of hydrocarbon compound (d2) is, in each case, between 40 to 80 mol%, preferably 45 to 75 mol%, and particularly preferably 50 to 70 mol%, based on the total content of the blowing agents (d1) and (d2).

[0076] The foaming agent (d) is preferably used in such an amount that the free foam density of the polyisocyanate rigid foam obtained by the present invention is between 10 and 100 g / l, preferably between 20 and 75 g / l, and particularly between 30 and 50 g / l.

[0077] The flame retardant (e) used may generally be a flame retardant known from the prior art. Examples of suitable flame retardants include brominated alcohols such as brominated esters, brominated ethers (Ixol), and dibromoneopentyl alcohol, tribromoneopentyl alcohol and PHT-4-diol, as well as chlorinated phosphates such as tris(2-chloroethyl) phosphate, tris(2-chloropropyl) phosphate (TCPP), tris(1,3-dichloropropyl) phosphate, tricresyl phosphate, tris(2,3-dibromopropyl) phosphate, tetrakis(2-chloroethyl)ethylenediphosphate, dimethylmethanephosphonate, diethyldiethanolaminomethylphosphonate, and commercially available halogenated flame retardant polyols. Other phosphates or phosphonates that can be used as liquid flame retardants include diethylethanephosphonate (DEEP), triethyl phosphate (TEP), dimethylpropylphosphonate (DMPP), and diphenyl cresyl phosphate (DPC). Flame retardants having isocyanate reactive groups are considered to belong to both component (e) and component (b) of the flame retardant.

[0078] Other flame retardants that can be used to impart flame retardancy to rigid polyurethane foam include inorganic or organic flame retardants such as red phosphorus, red phosphorus-containing preparations, aluminum oxide hydrate, antimony trioxide, arsenic oxide, ammonium polyphosphate and calcium sulfate, expandable graphite and cyanuric acid derivatives, e.g., melamine, and mixtures of at least two flame retardants, e.g., ammonium polyphosphate and melamine, and optionally corn starch or ammonium polyphosphate, melamine and expandable graphite; aromatic polyesters may also be optionally used for this purpose.

[0079] Preferred flame retardants do not contain bromine. Particularly preferred flame retardants consist of atoms selected from the group consisting of carbon, hydrogen, phosphorus, nitrogen, oxygen, and chlorine, and more particularly atoms selected from the group consisting of carbon, hydrogen, phosphorus, and chlorine.

[0080] Preferred flame retardants do not contain groups that react with isocyanate groups. The flame retardants are preferably liquid at room temperature. Particularly preferred are TCPP, DEEP, TEP, DMPP, and DPC, as well as oligomeric halogen-free flame retardants, e.g., Fyrol® PNX(ICL) and Levagard® 2000(Lanxess), and / or incorporateable phosphorus-based flame retardants, e.g., Veriquel® R-100(ICL) and Levagard® 2100(Lanxess), particularly TCPP and TEP, and even more preferred is TEP, which, in continuous processing, provides a defect-free foam surface beneath the lower outer layer and reduces the release of caustic combustion gases in the event of a fire.

[0081] The proportion of the flame retardant (e) is generally 1% to 40% by mass, preferably 5% to 30% by mass, and particularly preferably 8% to 25% by mass, based on the total mass of components (b) to (g).

[0082] The reaction mixture for producing polyurethane foam according to the present invention may optionally be mixed with further auxiliary agents and / or additives (f). These may include, for example, surfactants, foam stabilizers, cell regulators, fillers, light stabilizers, dyes, pigments, hydrolysis stabilizers, and fungicides and bacteriostatic substances.

[0083] Possible surface-active substances include compounds that are used, for example, to help homogenize the starting material and are also suitable for optionally adjusting the cellular structure of the plastic. Examples include emulsifiers, such as castor oil sulfate or sodium salts of fatty acids, salts of fatty acids and amines, such as diethylamine oleate, diethanolamine stearate, diethanolamine ricinoleate, salts of sulfonic acids, such as alkali metal or ammonium salts of dodecylbenzene or dinaphthylmethanedisulfonic acid, and ricinoleic acid, such as siloxane-oxyalkylene copolymers and other organopolysiloxanes and dimethylpolysiloxanes. Similarly, polyoxyalkylenes and oligomeric acrylates having fluoroalkane radicals as side groups are suitable for improving the emulsifying effect, cellular structure and / or stability of the foam. Surface-active substances are typically used in amounts of 0.01 to 10 parts by mass based on 100 parts by mass of component (b).

[0084] The foam stabilizers used may be conventional foam stabilizers, such as silicone-based ones, such as siloxane-oxyalkylene copolymers and other organopolysiloxanes.

[0085] Fillers, (especially reinforcing fillers), should be understood to mean known, conventional organic and inorganic fillers, reinforcing agents, weighting agents, agents for improving the wear behavior of paints, coating compositions, etc. Individual examples include inorganic fillers such as silica-containing minerals, phyllosilicates such as antigorite, serpentinite, hornblende, amphibole, chrysotile, and talc, metal oxides such as kaolin, aluminum oxide, titanium oxide, and iron oxide, metal salts such as chalk and barite, inorganic pigments such as cadmium sulfide and zinc sulfide, and even glass. Natural and synthetic fibrous minerals such as kaolin (clay), aluminum silicate, coprecipitates of barium sulfate and aluminum silicate, and wollastonite, and metals, especially glass fibers of varying lengths are preferred, and these can be arbitrarily sized. Possible organic fillers include, for example, carbon, melamine, rosin, cyclopentadienyl resins and graft polymers, and polyester fibers derived from cellulose fibers, polyamide fibers, polyacrylonitrile fibers, polyurethane fibers, aromatic and / or aliphatic dicarboxylic acid esters, particularly carbon fibers.

[0086] Inorganic and organic fillers can be used individually or in mixture form, and the amounts of these added to the reaction mixture are advantageously 0.5 to 50% by mass, preferably 1 to 40% by mass, based on the mass of components (a) to (f), however, the content of mats, nonwovens and fabrics made of natural and synthetic fibers can reach up to 80% by mass, based on the mass of components (a) to (f).

[0087] Compound (g) is preferably a substance that is free-flowing at a temperature of 20°C and an ambient pressure of 1 bar. Examples of compound (g) include carboxylic acid esters such as lower alkanol esters of carboxylic acids, for example fatty acid ethyl esters or preferably fatty acid methyl esters, for example methyl caproate, methyl caprylate, methyl caprate, methyl laurate, methyl myristate, methyl palmitate, methyl oleate, methyl stearate, methyl linoleate, methyl linolenate and mixtures thereof, and particularly preferably biodiesel.

[0088] As compounds having a hydrophobic group (g), triglycerides are preferred, and oils and fats are particularly preferred, such as rapeseed oil, olive oil, corn oil, palm oil, pumpkin seed oil, sunflower oil, wheat seed oil, soybean oil, coconut oil, tall oil, cottonseed oil, grapeseed oil, apricot kernel oil, safflower oil, avocado oil, macadamia oil, pistachio oil, almond oil, flaxseed oil, sesame oil, hazelnut oil, peanut oil, walnut oil, evening primrose oil, sea buckthorn oil, safflower oil, borage seed oil, black cumin oil, wild rose oil, animal fat, and mixtures thereof can also be used.

[0089] According to the present invention, polyurethane foam is produced by mixing components (a) to (e), and (f) and (g) if present, to obtain a reaction mixture. To reduce complexity, premixtures may also be produced. These premixtures include at least one isocyanate component (A) containing polyisocyanate (a) and a polyol component (B) containing an isocyanate-reactive compound (b). Components (c) to (g) may be added to the isocyanate component (A) and polyol component (B) in whole or in part. Due to the high reactivity of isocyanates, components (c) to (g) are often added to the polyol component to avoid side reactions. However, the blowing agent (d1) may also be mixed with the isocyanate component (A) in particular. The physical blowing agents (d1) and (d2) are preferably added to the reaction mixture in a further flow, and the remaining components (d) to (g) are particularly preferably added to the polyol component (B). The reaction mixture can then be reacted to obtain polyurethane foam. In the context of the present invention, the reaction mixture should be understood to mean a mixture of isocyanate (a) and isocyanate-reactive compound (b) with a reaction conversion rate of less than 90% based on the isocyanate group.

[0090] The mixing of components to obtain the reaction reaction is carried out at an isocyanate index of 240 to 1000, preferably 240 to 800, preferably 240 to 600, particularly preferably 280 to 500, and especially 330 to 400. The starting components are mixed at a temperature of 15°C to 90°C, preferably 20°C to 60°C, and particularly 20°C to 45°C. The reaction mixture can be mixed by mixing with a high-pressure or low-pressure measuring device.

[0091] The reaction mixture can be reacted, for example, by placing it in a mold. This technique can be used to produce, for example, discontinuous sandwich elements.

[0092] The rigid foam according to the present invention is preferably manufactured on a continuously operating double belt line. The polyol component and the isocyanate component are weighed in a high-pressure device and mixed in a mixing head. The catalyst and / or blowing agent can be pre-wetted into the polyol mixture using a separate pump. The reaction mixture is continuously coated onto the outer layer. The lower and upper outer layers, having the reaction mixture, are introduced into a double belt on which the reaction mixture foams and hardens. After exiting the double belt, the continuous sheet is cut to the desired dimensions. This makes it possible to manufacture sandwich elements having a metallic outer layer or a flexible outer layer.

[0093] The upper and lower outer layers used may be the same or different, and may be flexible or rigid outer layers commonly employed in double-belt processes. These include metal outer layers such as aluminum or steel, asphalt outer layers, paper, nonwoven fabrics, plastic sheets such as polystyrene, plastic films such as polyethylene film, or wood outer layers. The outer layers may also be coated, for example, with conventional coatings or adhesion promoters. It is particularly preferable to use an outer layer that is impermeable to the air bubbles of the polyurethane foam.

[0094] Such processes are known and are described, for example, in "Kunststoffhandbuch, Vol. 7, Polyurethane," Carl Hanser Verlag, 3rd edition 1993, Chapter 6.2.2 or EP2234732.

[0095] The present invention ultimately provides a polyisocyanate-based rigid foam that can be obtained by the method according to the present invention, and a polyurethane sandwich element comprising such a polyisocyanate-based rigid foam according to the present invention.

[0096] The polyisocyanate-based rigid foam according to the present invention is characterized by exceptional mechanical properties, particularly exceptional compressive strength and exceptionally low thermal conductivity. The manufacturing of the sandwich element, particularly in a continuous double-belt process, further provides a sandwich element having exceptional surface quality (particularly surface quality facing the lower outer layer) of the polyisocyanate-based rigid foam.

[0097] The present invention will be described below with reference to examples.

[0098] The following input materials were used to produce the reaction mixtures shown in Tables 1, 2, and 4: Polyols: Polyesterol 1: An esterification product of terephthalic acid, oleic acid, diethylene glycol, and ethoxylated glycerol, having a hydroxyl value of 535 mg KOH / g, a hydroxyl value of 244 mg KOH / g, and a mass fraction of 15% oleic acid in the final product. This results in a proportion of hydrophobic groups in the total mass of Polyesterol 1 of approximately 13.3% by mass, based on the total mass of Polyesterol 1.

[0099] Polyesterol 2: Esterification products of phthalic anhydride, diethylene glycol, and monoethylene glycol, the final product having a hydroxyl value of 240 mg KOH / g and a mass fraction of 0% oleic acid.

[0100] Polyesterol 3: An esterification product of phthalic anhydride, soybean oil, and diethylene glycol, having a hydroxyl value of 194 mg KOH / g and a fatty acid mass fraction of 3.7% in the final product. This results in a proportion of hydrophobic groups of approximately 3.1% by mass of the total mass of polyesterol 3, based on the total mass of polyesterol 3.

[0101] Polyester polyol 4: An esterification product of phthalic anhydride, glycerol, oleic acid, and diethylene glycol, having a hydroxyl value of 195 mg KOH / g and a mass fraction of 3.7% oleic acid in the final product. This results in a proportion of hydrophobic groups of approximately 3.3% by mass of the total mass of polyester polyol 4, based on the total mass of polyester polyol 4.

[0102] Polyester polyol 5: Esterification products of phthalic anhydride, monoethylene glycol, and diethylene glycol, with a hydroxyl value of 215 mg KOH / g and a mass fraction of oleic acid of 15.8% in the final product. This results in a proportion of hydrophobic groups of approximately 14.0% by mass of the total mass of polyester polyol 5, based on the total mass of polyester polyol 5.

[0103] Polyethylene glycol having a hydroxyl value of 1:188 mg KOH / g. Flame retardant: TCPP: Tris(2-chloroisopropyl) phosphate, having a chlorine content of 32.5% by mass and a phosphorus content of 9.5% by mass. TEP: Triethyl phosphate with a phosphorus content of 17% by mass. Foam stabilizer: Tegostab (registered trademark) B8443: Silicone-containing foam stabilizer from Evonik catalyst: Catalyst A: Trimerizing catalyst consisting of 36.2% by mass of potassium formate dissolved in 63.7% by mass of monoethylene glycol. Catalyst B: A catalyst consisting of 23.1% by mass of bis(2-dimethylaminoethyl) ether and 76.9% by mass of dipropylene glycol. Chemical foaming agents: Amasil 85%: Formic acid aqueous solution (85% by mass aqueous solution) Physical foaming agents: Pentane S80 / 20: A mixture of 80% by mass of n-pentane and 20% by mass of isopentane. A mixture of 70% cyclopentane by mass and 30% isopentane by mass. A mixture of 95% cyclopentane by mass and 5% isopentane by mass. Solstice® LBA: 1-chloro-3,3,3-trifluoropropene manufactured by Honeywell. (Z)-1,1,1,4,4,4-hexafluoro-2-butene manufactured by Opteon(trademark) 1100:Chemours. A mixture of 1:55.88% by mass of cyclopentane 70 and 44.12% by mass of Solstice® LBA yields a blowing agent mixture containing approximately 70 mol% cyclopentane 70. A mixture of 56.12% by mass of pentane S80 / 20 and 43.88% by mass of Solstice® LBA yields a blowing agent mixture containing approximately 70 mol% pentane S80 / 20. Isocyanates: Lupranat(registered trademark) M50: Approximately 550 mPa at 25℃ * BASF polymer methylenediphenyl diisocyanate (PMDI) with viscosity s

[0104] The polyol components shown in Tables 1, 2, and 4 were produced from the above starting materials and reacted in a continuous double-belt process in the laboratory and under high pressure.

[0105] Experimental form for establishing identical density and fiber time (gel time): The polyol components shown in Table 1, by changing the physical blowing agent and catalyst B, achieve the same fiber time of 53 seconds ± 2 seconds and cup foam density of 44 kg / m². 3 ±2kg / m 3 The mixture was adjusted as follows. The amount of catalyst A was selected so that the final form in all settings had the same concentration. The polyol components thus adjusted were reacted with Lupranat® M50 in a mixing ratio such that the index in all settings was 330 ± 10. Thus, 80 g of the reaction mixture was reacted in a paper cup by vigorously mixing it at 1400 rpm for 8 seconds using a laboratory stirrer.

[0106] The polyol components shown in Table 2 were adjusted to the same fiber time of 53 seconds ± 2 seconds and cup foam density of 42 kg / m 3 ±2 kg / m 3 by changing the physical blowing agent and catalyst B. The amount of catalyst A was selected such that the cured foams of all settings had the same concentration. The polyol components thus adjusted were reacted with Lupranat® M50 at a mixing ratio such that the index of all settings was 330 ± 10. Thus, 80 g of the reaction mixture was reacted in a paper cup by vigorously mixing at 1400 rpm for 8 seconds using a laboratory stirrer.

[0107] The polyol components shown in Table 3 were adjusted to the same fiber time of 53 seconds ± 2 seconds and cup foam density of 42 kg / m 3 ±2 kg / m 3 by changing the physical blowing agent and catalyst B. The amount of catalyst A was selected such that the cured foams of all settings had the same concentration. The polyol components thus adjusted were reacted with Lupranat® M50 at a mixing ratio such that the index of all settings was 210 ± 10. Thus, 80 g of the reaction mixture was reacted in a paper cup by vigorously mixing at 1400 rpm for 8 seconds using a laboratory stirrer.

[0108] In this way, reaction mixtures adjusted to equivalent density and fiber time were then used to produce rigid foam blocks, from which test specimens for thermal conductivity and compression strength measurements were taken. To produce a foam block for thermal conductivity measurement, 450 g of the reaction mixture was reacted in a paper cup by vigorously mixing at 1400 rpm for 6 seconds using a laboratory stirrer. Next, the reaction mixture was transferred to a mold of a box having an open top and dimensions of 150 mm × 120 mm × 120 mm. Test specimens for thermal conductivity measurement having dimensions of 200 mm × 200 mm × 30 mm were always taken from the center of the foam block in the foam rising direction.

[0109] Thermal conductivity was measured at an average temperature of 23°C using a λ-Meter EP500e thermal conductivity meter from Lambda Messtechnik GmbH Dresden. The thermal conductivity values ​​reported in Tables 1 and 2 are the average of repeated measurements from two test specimens from two different but identically manufactured foam blocks.

[0110] To determine the compressive strength according to DIN EN 826, nine additional test specimens measuring 50 mm × 50 mm × 50 mm were taken from the same foam block. Here again, the test specimens were always taken in the same manner. Of the nine test specimens, three were rotated so that the test was performed in the opposite direction to the rising direction (top) of the foam. Of the nine test specimens, three were rotated so that the test was performed specifically with respect to the rising direction (x direction) of the foam. Of the nine test specimens, three were rotated so that the test was performed perpendicular to the rising direction (y direction) of the foam.

[0111] Next, the nine measured compressive strengths were averaged and reported as values ​​(compressive strength 3D) in Tables 1 and 2.

[0112] [Table 1]

[0113] [Table 2]

[0114] [Table 3]

[0115] Since the thermal conductivity of the foaming agent Solstice® LBA is lower than that of cyclopentane 70 and pentane S80 / 20, it is expected that foams produced in the laboratory using foaming agent mixtures 1 and 2 will also have low thermal conductivity. However, it was surprisingly found that using polyol components with a lower hydrophobic group content in components (b) to (g) significantly reduced thermal conductivity and dramatically improved the compressive strength of the experimental foam.

[0116] When the polyol component of the present invention in Example 13 is foamed at a reduced index of 210 (Example 19), the thermal conductivity increases significantly, and the compressive strength of the foam decreases significantly. Continuous production of sandwich elements using a double-belt process: In addition to experimental foam, 80mm thick composite material elements were manufactured using a double-belt process. The manufacturing process involved reacting the following polyol components, temperature-controlled at 20°C ± 1°C, with Lupranat® M50, also heated to 20°C ± 1°C. The amount of Lupranat® M50 was always selected to ensure that all manufactured rigid foams had an isocyanate index of 345 ± 10.

[0117] In the manufacturing of composite material elements, a 0.05 mm thick aluminum foil heated to 35°C ± 2°C or a 0.5 mm thick aluminum plate heated to 40°C ± 2°C was used as the lower outer layer. Both upper layers are industry standards and are also used in conventional continuous production methods for sandwich panels. The temperature of the double belt was always 60°C ± 1°C.

[0118] To produce a composite material element with a thickness of 80 mm, the amounts of catalyst B and physical blowing agent were selected such that the gel time of the reaction mixture was exactly 28 seconds, the contact time between the reaction mixture and the upper belt was exactly 23 seconds, and the foam had an overall density of 38.0 ± 1.5 g / l.

[0119] To determine thermal conductivity, compressive strength, and foam surface, a 2.0 m long, 1.25 m wide sample (the sample required for each test was always taken from the same location) was collected after successfully adjusting the foam parameters.

[0120] Determining the compressive strength of sandwich foam: After storage for 24 hours under standard climatic conditions, further specimens with dimensions of 100 mm × 100 mm × sandwich thickness were taken from the sample specimen using a band saw. The specimens were taken from the same area (left, center, right) distributed across the width of the element (left, center, right), and the compressive strength of the foam was determined according to the sandwich standard DIN EN ISO 14509-A.2 in accordance with EN 826.

[0121] Determining the thermal conductivity of sandwich foam: After being stored for 24 hours under standard climatic conditions, a band saw was used to cut a further specimen from the sample test piece, measuring 200 mm × 200 mm × 30 mm. The specimen was taken at the midpoint between the thickness and width of the sandwich element.

[0122] Thermal conductivity was measured at an average temperature of 23°C using a λ-Meter EP500e thermal conductivity meter from Lambda Messtechnik GmbH Dresden. The thermal conductivity values ​​reported in Table 5 are the average values ​​of repeated measurements of two test specimens.

[0123] Evaluation of the foam surface after delamination of the lower outer layer: After mechanically removing the aluminum foil and aluminum sheet (lower outer layer) to which the reaction mixture liquid had been directly applied using a double-belt process, the foam surface was first assessed and evaluated, where Grade 1 represents the best foam surface and Grade 5 represents the worst foam surface.

[0124] [Table 4]

[0125] [Table 5]

[0126] When using the same amount of the same blowing agent mixture, it is clear that even in a double-belt process, the use of the polyol components of the present invention (Examples 20, 26, and 30) having a small proportion of hydrophobic groups in components (b) to (g) achieves significantly lower thermal conductivity and increased compressive strength of the resulting foam compared to the polyol component (Example 27) having a high proportion of hydrophobic groups in components (b) to (g). However, polyol components with a smaller proportion of hydrophobic groups in components (b) to (g) do not show a continuous improvement in thermal conductivity even as the proportion of halogenated olefins compared to cyclopentane 95 continues to increase. The minimum thermal conductivity is achieved when the molar ratio of halogenated olefins to the molar ratio of cyclopentane 95 is 20 to 55 mol%. Surprisingly, an increase in the molar ratio of halogenated olefins in combination with the polyol components of the present invention beyond 70 mol%, preferably 65 mol%, more preferably 60 mol%, and especially beyond 55 mol%, results in an increase in the thermal conductivity of the manufactured foam. Furthermore, when the proportion of both halogenated olefins exceeds 70 mol%, the foam quality on the underside deteriorates (Examples 22, 23, and 25). When pentane S80 / 20 is also used, polyol components with a low proportion of hydrophobic groups in components (b) to (g) exhibit significantly improved thermal conductivity compared to the non-inventive polyol components (Example 28 vs. Example 29). However, compared to the non-inventive reaction mixture, the use of pentane S80 / 20 significantly reduces the thermal conductivity and foam quality on the underside of different outer layers (Example 28).

Claims

1. A process for producing a polyisocyanurate foam, comprising: a) an aromatic polyisocyanate, b) an isocyanate-reactive compound containing at least one polyether polyol (b1) and / or polyester polyol (b2), wherein the number-average content of isocyanate-reactive hydrogen atoms in components (b1) and (b2) is at least 1.7, an isocyanate-reactive compound, c) a catalyst, d) a blowing agent, e) a flame retardant, f) optionally, auxiliary substances or additives not falling within the definitions of (a) to (e), g) optionally, a compound having an aliphatic hydrophobic group (an aliphatic hydrocarbon group having more than 6 and less than 100 directly adjacent carbon atoms) not falling within the definitions of (a) to (f), are mixed to obtain a reaction mixture, which is cured to obtain a rigid polyisocyanurate foam, the blowing agent (d) contains at least one aliphatic halogenated hydrocarbon compound (d1) composed of 2 to 5 carbon atoms, at least one hydrogen atom, and at least one fluorine atom and / or chlorine atom, the compound (d1) contains at least one carbon-carbon double bond, the blowing agent (d) further contains a hydrocarbon compound (d2) having 4 to 8 carbon atoms, and in each case based on the total content of the blowing agents (d1) and (d2), the molar ratio of the halogenated hydrocarbon compound (d1) is 20 to 60 mol%, and the molar ratio of the hydrocarbon compound (d2) is between 40 and 80 mol%, components (b) to (g) contain 0 to 4.0% by mass of an aliphatic hydrophobic group (an aliphatic hydrocarbon group having more than 6 and less than 100 directly adjacent carbon atoms) based on the total mass of components (b) to (g), The method for producing a polyisocyanurate foam, wherein the mixing for obtaining the reaction mixture is carried out at an isocyanate index of at least 240.

2. The method according to claim 1, wherein the hydrocarbon compound (d2) contains at least 60 mol% of an alicyclic hydrocarbon compound based on the total mass of the hydrocarbon compound (d2).

3. The method according to claim 1 or 2, wherein the hydrocarbon compound (d2) is selected from pentane isomers.

4. The method according to any one of claims 1 to 3, wherein the halogenated hydrocarbon compound (d1) is 1-chloro-3,3,3-trifluoropropene.

5. The method according to any one of claims 1 to 4, wherein the blowing agent contains formic acid.

6. The method according to any one of claims 1 to 5, wherein the catalyst (c) comprises at least one amine catalyst having a tertiary amine group and at least one ammonium or alkali metal carboxylate catalyst.

7. The method according to claim 6, wherein at least one amine catalyst having a tertiary amine group is selected from the group consisting of pentamethyldiethylenetriamine and bis(2-dimethylaminoethyl)ether, and the at least one alkali metal carboxylate catalyst is selected from the group consisting of potassium formate, potassium acetate and potassium 2-ethylhexanoate.

8. In any case, the compound (b) having at least one isocyanate-reactive hydrogen atom comprises 0 to 30% by mass of polyether polyol (b1) and 70 to 100% by mass of polyester polyol (b2) based on the total mass of polyether polyol (b1) and polyester polyol (b2). The method according to any one of claims 1 to 7.

9. The method according to any one of claims 1 to 8, wherein the polyether polyol (b1) is a reaction product of a starter molecule having a functionality of 2 to 4 and an alkylene oxide containing ethylene oxide, and has a hydroxyl value of 150 to 300 mgKOH / g.

10. The method according to any one of claims 1 to 9, wherein the polyester polyol (b2) is obtained using an aromatic dicarboxylic acid or a derivative thereof.

11. The method according to any one of claims 1 to 10, wherein the flame retardant (e) used is only a halogen-free flame retardant.

12. The method according to any one of claims 1 to 11, wherein the reaction mixture is applied to a continuously moving outer layer.

13. The method according to claim 12, wherein the application of the reaction mixture to the continuously moving outer layer is carried out on a double belt line for the production of sandwich elements.

14. A premix containing an isocyanate component (A) containing an aromatic polyisocyanate (a) and a polyol component (B) containing an isocyanate-reactive compound (b) is used for the production of the reaction mixture, and further components (c) to (g) are added in whole or in part to component (A) or component (B). The method according to any one of claims 1 to 13.

15. A rigid polyisocyanurate foam obtained by the method according to any one of claims 1 to 14.