Open-cell rigid polyurethane foam comprising recycled polyols

Abstract

A polyol composition comprising a) 1 to 30 wt.-% polyol A), wherein the polyol A) is a recycled polyol obtained by depolymerization of a polyurethane foam, b) 30 to 75 wt.-% polyether polyol B) having a functionality in the range of 3.5 to 8, wherein at least one starter compound of the polyether polyol P1) is a monosaccharide, oligosaccharide, polysaccharide, and / or a sugar alcohol and has at least 4 active hydrogen atoms; c) >0 to 68 wt.-% polyether polyol C) having an OH number in the range of 20 to 200 mg KOH / g) and being a reaction product of starter compounds with at least two alkylene oxide reactive hydrogen atoms with alkylene oxides, and d) an amine catalyst d1) which has at least one functional group reactive towards isocyanates and / or a metal catalyst d2) chosen from carboxylic acid salts of alkali metals, carboxylic acid salts of alkaline earth metals and carboxylic acid salts of ammonium, wherein the amounts of the polyols are based on the total amount of polyols in the polyol composition.

Description

[0001] 240998

[0002] 1

[0003] Open-cell rigid polyurethane foam comprising recycled polyols

[0004] Field of the invention

[0005] The present invention relates to a polyol composition comprising a recycled polyol, a process for the production of open-cell rigid polyurethane foam by reacting at least one isocyanate with the polyol composition, an open-cell rigid polyurethane foam, the use of the open-cell rigid polyurethane foam as a core material in vacuum insulation panels, and a vacuum insulation panel.

[0006] Background

[0007] Open-cell rigid polyurethane foams have long been used as a core material for the production of vacuum insulation panels (VIPs). One of the biggest technical advantages of open-cell rigid polyurethane foams over alternative inorganic core materials based on fumed silica or glass fibers is the lower weight and easier recyclability of the VIPs. VIPs with a lower weight have a cost advantage due to the lower material requirement and an advantage during transport, as they cause lower energy consumption per distance travelled.

[0008] VIPs are normally produced discontinuously in the form of block foams. Since the structure of the foams in the edge area does not meet the requirements for core materials for VIPs, they must be removed after production. This creates unavoidable production waste that has to be disposed of. The disposal of the production waste creates disposal costs. Additionally, the common practice of burning the production waste for energy production creates CO2 emissions. Furthermore, the loss of material reduces the overall profitability of the process.

[0009] It is therefore desirable to find solutions that make it possible to recycle the production waste in the same application. This can be done through well-known chemical recycling processes such as glycolysis. In this process, the polyurethane rigid foam is liquefied by reaction with a glycol and a recycled polyol is obtained. The recycled polyol can then be reintegrated into the original application as part of a polyol component (closed loop approach). This saves raw materials and avoids waste, thus avoiding CO2 emissions from subsequent incineration. This leads to an improved product carbon footprint of the raw materials and the products manufactured from them.

[0010] Although both the production of recycled polyols from rigid foams by glycolysis and their use as a component of polyol composites in rigid foam systems can be regarded as known, recycled polyols have not yet been applied open-cell rigid foam systems. When such recycled polyols 240998

[0011] 2 are used in polyol components, foams with a significantly lower proportion of open cells are obtained even at very low proportions. In addition, the foams exhibit insufficient dimensional stability (shrinkage) and hardening.

[0012] For use in vacuum insulation panel (VIP) applications, it is crucial that the rigid polyurethane foam has a high content of open cells. The use of rigid polyurethane foams with comparatively low proportions of open cells for an application as a core material leads to an increase in the thermal conductivity of the VIPs and is not acceptable. Rigid polyurethane foams with only partially open cells show higher thermal conductivity shortly after evacuation. This is caused by the negative contribution of cell gases in the closed cells. The thermal conductivity deteriorates even further over time, as there is an increase in the internal pressure in the VIP. This is caused by diffusion of the cell gases from the closed cells into the continuous volume of the open cells.

[0013] It was therefore the object of the invention to provide a polyol composition comprising a recycled polyol which can be used in the preparation of open-cell rigid polyurethane foams. In addition to a high content of open cells, the foams prepared using the polyol composition should have a good dimensional stability, good hardening properties, and a low thermal conductivity. A good compression strength is also desirable.

[0014] Detailed description

[0015] The object was surprisingly achieved by a polyol composition comprising a) 1 to 30 wt.-% polyol A), wherein the polyol A) is a recycled polyol obtained by depolymerization of a polyurethane foam, b) 30 to 75 wt.-% polyether polyol B) having a functionality in the range of 3.5 to 8, wherein at least one starter compound of the polyether polyol B) is a monosaccharide, oligosaccharide, polysaccharide, and / or a sugar alcohol and has at least 4 active hydrogen atoms; c) >0-68 wt.-% polyether polyol C) having an OH number in the range of 20 to 200 mg KOH / g and being a reaction product of starter compounds with at least two alkylene oxide reactive hydrogen atoms with alkylene oxides, and d) an amine catalyst d1) which has at least one functional group reactive towards isocyanates and / or a metal catalyst d2) chosen from carboxylic acid salts of alkali metals, carboxylic acid salts of alkaline earth metals and carboxylic acid salts of ammonium, e) wherein the amounts of the polyols are based on the total amount of polyols in the polyol composition. 240998

[0016] 3

[0017] The object was likewise achieved by a process for the production of open-cell rigid polyurethane foams by reacting at least one di- or polyisocyanate with the polyol composition; an open-cell polyurethane foam obtainable by the process; an open-cell polyurethane foam for use in vacuum insulation panels having a recycled content in the range of 0.5 to 10 wt.-%, based on the weight of the foam; the use of the open-cell rigid polyurethane foam as a core material of vacuum insulation panels; and a vacuum insulation panel comprising the open-cell rigid polyurethane foam.

[0018] The polyurethane foams prepared using the polyol composition according to the invention have a high content of open cells as well as good hardening properties. Additionally, they have a low thermal conductivity and a good compression strength. The foams are well suited for the use as a core material in vacuum insulation panels.

[0019] The term “polyurethane” is known by the person skilled in the art as including not only polymers containing urethane groups but as also including polymers containing no or very low amounts of urethane groups, as long as these polymers are derived from difunctional or polyfunctional isocyanates, see Polyurethane Handbook, 2ndedition 1993, editor Guether Oertel, Carl Hanser Verlag Munich, Chapter 2.1.1. Examples are polyetherureas, polyisocyanurates, polyureas and polycarbodiimides. Polymers containing urethane groups are preferred as polyurethanes.

[0020] The OH number (also called hydroxyl number or hydroxyl value) can be determined by means of well-established methods. By way of example, the OH number can be determined according to DIN 53240 (1971-12).

[0021] The functionality of a polyol, especially of the polyols A), B), C), D) and other polyols to be used according to the invention, within the context of the present invention means the number of alkylene oxide reactive hydrogen atoms per mole of starter compound or per mole of mixture of the starter compounds prior to the time of alkylene oxide metering. The time of the alkylene oxide metering is in this case the start of the addition of the alkylene oxide component to the starter compound(s). The calculation takes into account all alkylene oxide-reactive hydrogen atoms of the starter compound(s) that are present in the starter mixture.

[0022] The functionality F in the context of the present invention is calculated according to the following formula (I): 240998

[0023] 4

[0024] = moles of starter i ft = functionality of starter i m = number of starters in the starter mixture

[0025] F = functionality

[0026] The functionality F of a polyol produced from a mixture of two starter compounds (m=2) is calculated as follows:

[0027] F = (moles of starter compound A * functionality of starter compound A + moles of starter compound B * functionality of starter compound B) / (moles of starter A + moles of starter B).

[0028] The functionality F determined by the formula presented above is also called equivalent functionality or average functionality and is known to those skilled in the art as a readily accessible method for determining the functionality of polyols, see M. lonescu “Chemistry and Technology of Polyols for Polyurethanes”, 2005, Rapra Technology Limited, pages 34 to 39.

[0029] The functionality of the polyether polyols A), B), C) and D) as well as other polyols, as defined above according to the invention, can differ from the functionality after commencement of the addition of at least one alkylene oxide, that is, during the reaction of the at least one alkylene oxide with a starter compound, or of the reaction product, since during the reaction there is formation of by-products such as glycols and unsaturated monofunctional constituents. The side-reactions are known in the literature. The functionality of the polyether polyols A), B), C) and D) as well as other polyols can thus also be referred to as the functionality of the starter compound or starter compound mixture used for the preparation of the respective polyol.

[0030] A polyol in the context of the present invention is an organic compound that contains at least two hydrogen atoms that are reactive towards isocyanate. Examples of polyols are polyether polyols, polyester polyols, polyether ester polyols, polymer polyols and polycarbonate polyols.

[0031] A polyether polyol in the context of the present invention is an organic compound that contains at least ether bonds in the chain and OH groups as functional groups. Polyether polyols are reaction products of starter compounds with at least two alkylene oxide reactive hydrogen atoms with alkylene oxides. Starter compounds for polyether polyols include compounds with at least two OH groups as well as polyamines with at least one NH2 group. Further starter compounds are fatty acid esters like biodiesel. The preparation of polyether polyols is known per se to those skilled in the art. Starter compounds are often also called starter molecules, starter materials, starting compounds, or starters. 240998

[0032] 5

[0033] Preference is given to using one or more C2 to C4 alkylene oxides. Suitable C2 to C4 alkylene oxides are ethylene oxide, 1,2-propylene oxide, 1,3-propylene oxide, 1,2- or 2,3-butylene oxide, in each case either alone or in the form of mixtures. Ethylene oxide and / or 1,2-propylene oxide are particularly preferred. Hereinafter, the term “propylene oxide” is used to mean 1,2-propylene oxide.

[0034] The polyol composition according to the present invention comprises at least one polyol A), at least one polyol B), and at least one polyol C). Preferably, the polyol composition additionally comprises at least one polyol D). The polyol composition additionally comprises an amine catalyst.

[0035] Polyol A)

[0036] Polyol A) is a recycled polyol obtained by depolymerization of a polyurethane foam. More preferred, the polyol A) is obtained by depolymerization of a rigid polyurethane foam. Even more preferred, the polyol A) is obtained by depolymerization of an open-cell rigid polyurethane foam.

[0037] The depolymerization of a polyurethane foam may take place via glycolysis or hydrolysis. Hydrolysis and glycolysis of polyurethane foams per se are known to the skilled person.

[0038] Polyol A) is preferably obtained by glycolysis of a polyurethane foam, more preferred by glycolysis of a rigid polyurethane foam, even more preferred by glycolysis of an open-cell rigid polyurethane foam. The open-cell rigid polyurethane foam may comprise residues from opencell rigid polyurethane foam production and / or open-cell rigid polyurethane foam waste.

[0039] The polyol A) is preferably prepared by glycolysis of polyurethanes using short-chain, in particular bifunctional and trifunctional, alcohols in a manner known per se. Particularly advantageously, the polyol A) is prepared in the presence of glycidyl ethers.

[0040] The polyurethane foam is preferably prepared prior to the glycolysis reaction, for example by shredding or grinding. The aim of the preparation of the polyurethane foam is to increase its surface area. The prepared polyurethane foam may be a powder.

[0041] The glycolysis reaction for the preparation of the polyol A) preferably comprises mixing the polyurethane foam (a) at least with at least one polyalcohol (b), optionally at least one catalyst (c), and optionally other components (d) and reacting the mixture to obtain the recycled polyol A). 240998

[0042] 6

[0043] The polyalcohol (b) has an OH number in the range of 220 to 1850 mg KOH / g, more preferred in the range of 240 to 1850 mg KOH / g, more preferred in the range of 250 to 1500 mg KOH / g, even more preferred in the range of 400 to 1000 mg KOH / g. Preferably suitable polyalcohols

[0044] (b) are liquid at 40 °C. The polyalcohol may contain only primary OH groups, only secondary OH groups or both primary and secondary OH groups. The polyalcohol (b) is preferably chosen from monoethylene glycol, diethylene glycol, 1 ,2- or 1,3-propanediol, triethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, glycerol, trimethylolpropane, polyethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1 ,10-decanediol, and pentaerythritol as well as alkoxylates of common starter molecules as for example of the same starters and / or of other common polyalcohols, such as monoethylene glycol, diethylene glycol, 1 ,2- or 1,3-propanediol, dipropylene glycol, polypropylene glycol, glycerol, trimethylolpropane, and pentaerythritol. The polyalcohol (b) is preferably a dihydric alcohol. Preferably used is diethylene glycol.

[0045] The amount of polyalcohol (b) used is preferably 10 to 50 % by weight, more preferred 15 to 40 % by weight and especially preferred 20 to 35 % by weight, each based on the total weight of the components (a) to (d). It is known to a person skilled in the art that molar amount and hydroxyl value of the applied polyalcohol (b) influences the hydroxyl value of the recycled polyol obtained. The higher the molar amount of polyol (b), the higher the final OH number of the recycled polyol, and the higher the OH number of the polyol (b), the higher the OH number of the recycled polyol obtained.

[0046] As catalyst (c) catalysts can be used comprising at least one basic catalyst (c) catalyzing esterification of alcohol groups and carboxylic acids. Such catalysts are used for the production of polyesters and their transesterification and are well known in the art. Examples of catalysts

[0047] (c) are alkali- or alkali earth metal carboxylates (c1) such as for example potassium carboxylate and transition-metal-based catalysts (c2) as iron-based catalysts, cadmium-based catalysts, cobalt-based catalysts, lead-based catalysts, zinc-based catalysts, antimony-based catalysts, titanium-based catalysts, and tin-based catalysts. Transition-metal-based catalysts (c2) include metal catalysts such as titanium catalysts, as described in "Modern Polyesters: Chemistry and Technology of Polyesters and Copolyesters", Chapter 2, Wiley, 2003, ISBN 0-471-49856-4. Examples of transition metal based catalysts (d2) are tin(ll) salts of organic carboxylic acids, e.g. tin(ll) acetate, tin(ll) octoate, tin(ll) ethylhexanoate and tin(ll) laurate, and the dialkyltin(IV) salts of organic carboxylic acids, e.g. dibutyltin diacetate, dibutyltin dilaurate, zinc(ll) acetate, dibutyltin maleate and dioctyltin diacetate, and the titanium alkoxides, e.g. tetrabutyl orthotitanate, and also bismuth carboxylates, such as bismuth(lll) neodecanoate, bismuth 2- ethylhexanoate and bismuth octanoate, or mixtures thereof. 240998

[0048] Catalysts (c) can be used at a concentration of from 0.01 to 10% by weight, in particular from 0.5 to 8% by weight, as catalyst or, respectively, catalyst combination, based on the weight of components (a), (b), (c) and (d).

[0049] Further compounds (d) can for example be chosen from deamination agents, esters of fats or PET waste, mono carboxylic acids and mono alcohols.

[0050] Deamination agents are compounds which, when added to mixtures of alcohols and aromatic amines, react preferentially with the aromatic amines, even if there is an excess of alcohol. These include fatty acids, isocyanates, glycidyl ethers or epoxidized native oils.

[0051] For example, stearic acid, palmitic acid, dodecanoic acid, erucaic acid, linoleic acid, linolenic acid, oleic acid or mixtures of fatty acids can be used as fatty acids. Fatty acids and their use for deamination are described, for example, in DE 102009026898.

[0052] Isocyanates for deamination are preferably those that have exclusively secondary or tertiary or secondary and tertiary aliphatic bound isocyanate groups, for example bis-1 ,3(2- isocyanatopropyl)benzene. Isocyanates and their use for deamination are described, for example, in EP899292.

[0053] As glycidyl ethers any compound comprising epoxide groups preferably compounds containing one or two epoxy groups in the molecule can be used. The monofunctional glycidyl ethers of the general formula (i) proved to be particularly suitable:

[0054] Wherein R = Phenyl, Cyclohexyl, Methylcyclohexyl, Benzyl, i-Propyl, i-Butyl or methyl- and / or ethyl-branched hydrocarbon chains having 5 to 10 carbon atoms in the straight chain and / or a group of the general formula (ii): 240998

[0055] 8

[0056] Wherein A stands for an alkyl residue having 1 bis 8 carbon atoms, n is 3 to 12 and m is 1 to 6.

[0057] As difunctional glycidyl ethers compounds according to formula (iii) are especially preferred: wherein R' = diphenylmethylene, 2,2-diphenylpropylene (bisphenol A), unbranched hydrocarbon chains with 4 to 10 carbon atoms or methyl and / or ethyl branched hydrocarbon chains with 4 to 8 carbon atoms in the straight chain. Glycidylethers and their use for deamination are for example disclosed in EP592952.

[0058] Epoxidized native fatty oils are those products that are obtained from at least single, preferably at least triple unsaturated natural oils, e.g. from soy, flax, castor and nuts of all kinds. The term "unsaturated" refers to a carbon-carbon double bond. Glycidylethers and their use for deamination are for example disclosed in EP718349.

[0059] As deamination agents, preferably glycidylethers are used. Preferred glycidylethers are monofunctional epoxy resins, such as 2-ethylhexyl glycidyl ether, isopropyl glycidyl ether, butyl glycidyl ether, cresyl glycidyl ether or monofunctional glycidyl ethers based on 2-ethylhexanol (Epilox P13-16, LEUNA-Harze GmbH), C12-C14 alcohols (Epilox P 13-18, LEUNA-Harze GmbH) or C13-C15 alcohols (Epilox P 13-19, LEUNA-Harze GmbH).

[0060] The amount of the deamination agent added to the reaction mixture is preferably 0 to 40 % by weight, more preferred 5 to 30 wt.-% and especially preferred 10 to 20 % by weight, each based on the total weight of the components (a) to (d).

[0061] Preferably, the polyurethane foam (a), the polyalcohol (b), and, if present, the catalyst (c) and, if present, the other components (d) are preferably mixed to form a reaction mixture, and reacting the reaction mixture at temperatures of 130 to 280 °C, preferably 160 to 250 °C and especially preferred 180 to 220 °C. The order in which they are added to the mixture is not limited. For example, all components can be added at the same time. Alternatively, the polyurethane foam (a) can be mixed with the polyalcohol (b) in a first step and the optional catalyst (c) and the optional deamination agent can be added afterwards. 240998

[0062] 9

[0063] The obtained recycled polyol may be further purified by filtration. By filtration, unsoluble components such as for example unreacted carbonates can be separated. In addition, by distillation volatile substances might be separated.

[0064] The polyether polyol A) preferably has a recycled content in the range of 15 to 55 wt.-%, more preferred 25 to 50 wt.-%, even more preferred 35 to 45 wt.-%, based on the weight of the polyether polyol A).

[0065] The polyol A) preferably contains less than 1wt.-%, preferably less than 1000 ppm, more preferred less than 100 ppm tertiary amines which (i) do not have functional groups that are reactive towards isocyanates and (ii) have a vapor pressure above 0.1 mbar at 20 °C. The vapor pressure of the tertiary amines which do not have functional groups that are reactive towards isocyanates is preferably above 0.01 mbar at 20 °C, more preferred above 0.001 mbar at 20 °C.

[0066] Preferably, the polyol A) has an OH number of at least 300 mg KOH / g, more preferred at least 400 mg KOH / g, even more preferred at least 450 mg KOH / g. Preferably, the polyol A) has an OH number of at most 600 mg KOH / g, more preferred at most 580 mg KOH / g, even more preferred at most 560 mg KOH / g.

[0067] The polyol A) preferably has an OH number in the range of 300 to 600 mg KOH / g, more preferred in the range of 400 to 580 mg KOH / g, even more preferred in the range of 450 to 560 mg KOH / g.

[0068] The functionality of the polyol A) is preferably at least 2. The functionality of the polyol A) is preferably at most 6, more preferred at most 5, even more preferred at most 4. The functionality of the polyol A) is preferably in the range of 2 to 6, more preferred in the range of 2 to 5, even more preferred in the range of 2 to 4.

[0069] The acid number of the polyol A) is preferably lower than 10 mg KOH / g. More preferred, the acid number of the polyol A is lower than 3 mg KOH / g, even more preferred lower than 0.3 mg KOH / g. The acid number can be determined by means of well-established methods. For example, the acid number can be determined according to DIN EN 1241 (May 1998).

[0070] The amine number of the polyol A) is preferably lower than 100 mg KOH / g. More preferred, the amine number of the polyol A) is lower than 70 mg KOH / g, even more preferred lower than 50 mg KOH / g. The amine number can be determined by means of well-established methods. For example, the amine number can be determined according to DIN 16945 (1989). 240998

[0071] 10

[0072] The polyol A) preferably has a methylenediamine concentration below 2500 ppm, more preferred below 1000 ppm, more preferred below 500 ppm, even more preferred below 100 ppm, based on the weight of the polyol A). The methylenediamine concentration can be determined by extraction with acetonitrile and subsequent high performance liquid chromatography (HPLC).

[0073] The polyol composition comprises at least 1 wt.-% polyol A), based on the total amount of polyols in the polyol composition. Preferably, the polyol composition comprises at least 10 wt.- %, more preferred at least 15 wt.-% polyol A), based on the total amount of polyols in the polyol composition. The polyol composition comprises at most 30 wt.-% polyol A), based on the total amount of polyols in the polyol compoisition. Preferably, the polyol composition comprises at most 28 wt.-%, more preferred at most 25 wt.-% polyol A), based on the total amount of polyols in the polyol composition.

[0074] The polyol composition comprises 1 to 30 wt.-% polyol A), based on the total amount of polyols in the polyol composition. Preferably, the polyol composition comprises 10 to 28 wt.-%, more preferred 15 to 25 wt.-% polyol A), based on the total amount of polyols in the polyol composition.

[0075] Polyether polyol B)

[0076] At least one starter compound of polyether polyol B) is a monosaccharide, oligosaccharide, polysaccharide, and / or a sugar alcohol and has at least 4 active hydrogen atoms. Additionally, also other starter compounds may be used. Possible starter compounds of polyol B) are monosaccharides, oligosaccharides, polysaccharides, sugar alcohols that all have at least 4 active hydrogen atoms, polyhydric alcohols, mixtures thereof, and alkoxylation products of the aforementioned compounds.

[0077] Preferably, the polyether polyol B) is an alkoxylation product of monosaccharides, oligosaccharides, polysaccharides, sugar alcohols, polyhydric alcohols, mixtures thereof, and alkoxylation products of the aforementioned compounds with C2 to C4 alkylene oxides, wherein at least one starter compound is a monosaccharide, oligosaccharide, polysaccharide, and / or a sugar alcohol and has at least 4 active hydrogen atoms. The C2 to C4 alkylene oxides are preferably selected from ethylene oxide and / or propylene oxide and / or mixtures of ethylene oxide and propylene oxide. Propylene oxide is particularly preferred.

[0078] The monosaccharides, oligosaccharides, polysaccharides, sugar alcohols, polyhydric alcohols and mixtures thereof can be reacted with alkylene oxides to form alkoxylation products. The 240998

[0079] 11 alkoxylation products are usually prepared using C2 to C4 alkylene oxides, preferably using ethylene oxide and / or propylene oxide. The alkoxylation products are then once again reacted, as starter compounds, with alkylene oxides in the preparation of the polyether polyols B), possibly in presence of further starter compounds. The use of the alkoxylation products as starter compounds is particularly advantageous when further starter compounds which are initially present as a solid or have a high viscosity are employed.

[0080] Alkoxylation products of monosaccharides, oligosaccharides, polysaccharides, polyhydric alcohols or mixtures thereof are preferably added during the preparation of the polyether polyols B) for the reduction of viscosity.

[0081] When calculating the functionality of the polyether polyol B) according to the invention, the above-mentioned alkoxylation products are correspondingly taken into account.

[0082] Examples of suitable starter compounds of the polyether polyol B) are sucrose, lactose, maltose, glucose, allose, altrose, gulose, idose, galactose, talose, fructose, sorbose, tagatose, mannose, psicose, sorbitol, mannitol, erythritol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, glycerol, trimethylolpropane, butane-1,4-diol, butane-1,3-diol, butane-1 ,2-diol, butane-2,3-diol, butane-1,2,4-triol, pentane- 1 ,3,5-triol, and pentaerythritol, wherein at least one starter compound is a monosaccharide, oligosaccharide, polysaccharide, and / or a sugar alcohol and has at least 4 active hydrogen atoms.

[0083] Preferably, the monosaccharides, oligosaccharides, polysaccharides and / or sugar alcohols that have at least 4 active hydrogen atoms are selected from the group consisting of sucrose, lactose, maltose, glucose, allose, altrose, gulose, idose, galactose, talose, fructose, sorbose, tagatose, mannose, psicose, erythritol, and sorbitol. Particularly preferred are sucrose and sorbitol. Sucrose is very particularly preferred.

[0084] It is preferred that at least one starter compound of the polyether polyol B) is a polyhydric alcohol having 2-3 active hydrogen atoms. Preferably, at least one starter compound of the polyether polyol B) is selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, glycerol, trimethylolpropane, butane-1 ,4-diol, butane-1,3-diol, butane-1,2-diol, butane-2,3-diol, butane- 1 ,2,4-triol, and pentane-1 ,3,5-triol. Particularly preferred polyhydric alcohols are diethylene glycol, dipropylene glycol, trimethylpropane, and glycerol; glycerol is very particularly preferred. 240998

[0085] 12

[0086] In a preferred embodiment, the starter compounds of the polyether polyol B) are selected from sucrose and sorbitol with glycerol as a second starter. Particularly preferred are starter mixtures comprising glycerol and sucrose.

[0087] In most cases, basic compounds are employed as alkoxylation catalysts for the reaction of the starter compound(s) with alkylene oxide(s). In industrial processes, these are mostly hydroxides of alkali metals, such as for example sodium, cesium or in particular potassium hydroxide. Alkali metal alkoxides, such as for example sodium methoxide, sodium or potassium methoxide or potassium isopropoxide, are known as catalysts. Also amine catalysts can be used.

[0088] The amine catalysts are preferably selected from the group comprising trialkylamines, such as for example trimethylamine, triethylamine, tripropylamine and tributylamine; dimethylalkylamines, such as for example dimethylethanolamine, dimethylcyclohexylamine, dimethylethylamine and dimethylbutylamine; aromatic amines, such as for example dimethylaniline, dimethylaminopyridine, dimethylbenzylamine, pyridine, imidazoles, such as for example imidazole, 4(5)-methylimidazole, 3-methylimidazole and 1 -hydroxypropylimidazole; guanidines and amidines, such as for example 1,5-diazabicyclo[4.3.0]non-5-ene and 1,5- diazabicyclo[5.4.0]undec-7-ene. Dimethylethanolamine and imidazole are preferred amine catalysts.

[0089] The alkoxylation catalyst for the reaction of the starter compound(s) with alkylene oxide(s) is preferably selected from potassium hydroxide and imidazole.

[0090] The functionality of the polyether polyol B) is at least 3.5, preferably at least 3.7, more preferred at least 3.9, even more preferred at least 4.0. The functionality of the polyether polyol (B) is at most 8.0. , preferably at most 7.9., more preferred at most 7.0, even more preferred at most 6.5. The functionality of the polyether polyol B) is in the range of 3.5 to 8, preferably in the range of 3.7 to 7.9, more preferred 3.9 to 7.0, even more preferred 4.0 to 6.5.

[0091] The OH number of the polyether polyol B) is preferably at least 350 mg KOH / g, more preferred at least 370 mg KOH / g, more preferred at least 390 mg KOH / g, even more preferred at least 400 mg KOH / g. The OH number of the polyether polyol (B) is preferably at most 800 mg KOH / g, more preferred at most 650mg KOH / g, more preferred at most 550 mg KOH / g, even more preferred at most 510 mg KOH / g. The OH number of the polyether polyol B) is preferably in the range of 350 to 800 mg KOH / g, more preferred in the range of 370 to 650 mg KOH / g, more preferred in the range of 390 to 550 mg, even more preferred in the range of 400 to 510 mg KOH / g. 240998

[0092] 13

[0093] Preferably, the functionality of the polyether polyol B) is in the range of 3.5 to 8.0 and the OH number in the range of 350 to 800 mg KOH / g, more preferred the functionality is in the range of from 3.7 to 7.9 and the OH value in the range of from 370 to 650 mg KOH / g, even more preferred the functionality is in the range of from 3.9 to 7.0 and the OH value in the range of from 390 to 550 mg KOH / g, in particular the functionality is in the range of 4.0 to 6.5 and the OH value in the range of from 400 to 510 mg KOH / g.

[0094] The polyol composition comprises at least 30 wt.-%, particularly preferred at least 35 wt.-% polyether polyol B), based on the total amount of polyols in the polyol composition. The polyol composition comprises at most 75 wt.-%, preferably at most 50 wt.-%, more preferred at most 48 wt.-%, even more preferred at most 45 wt.-% polyether polyol B), based on the total amount of polyols in the polyol composition.

[0095] The polyol composition comprises 30 to 75 wt.-% polyether polyol B), based on the total amount of polyols in the polyol composition. Preferably, the polyol composition comprises 25 to 50 wt- %, more preferred 30 to 48 wt.-%, even more preferred 35 to 45 wt.-% polyether polyol B), based on the total amount of polyols in the polyol composition.

[0096] The polyether polyol C) is a reaction product of starter compounds with at least two alkylene oxide reactive hydrogen atoms with alkylene oxides.

[0097] The polyether polyol C) has an OH number of at least 20 mg KOH / g, preferably at least 30 mg KOH / g, more preferred at least 50 mg KOH / g. The polyether polyol C) has an OH number of at most 200 mg KOH / g, preferably at most 160 mg KOH / g, more preferred at most 115 mg KOH / g.

[0098] The polyether polyol C) has an OH number in the range of 20 to 200 mg KOH / g), preferably in the range of 30 to 160 mg KOH / g, more preferred in the range of 50 to 115 mg KOH / g.

[0099] The polyether polyol C) preferably has a functionality of at least 1.5, more preferred at least 1.7, even more preferred at least 1.8. The polyether polyol C) preferably has a functionality of at most 3.2, more preferred at most 2.5, even more preferred at most 2.1.

[0100] The polyether polyol C) preferably has a functionality in the range of 1.5 to 3.2, more preferred in the range of 1.7 to 2.5, even more preferred in the range of 1.8 to 2.1. 240998

[0101] 14

[0102] Possible starter compounds for the polyether polyol C) are, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1 ,4-butanediol, butane-1,3-diol, butane-1,2-diol, butane-2,3-diol, butane-1,2,4-triol, pentane- 1 ,3,5-triol, glycerol and trimethylolpropane.

[0103] The polyether polyol C) is preferably a reaction product of at least one starter compound that has two active hydrogen atoms with C2 to C4 alkylene oxides. Preferably, all starter compounds of the polyether polyol C) have two active hydrogen atoms. The C2 to C4 alkylene oxides are preferably selected from ethylene oxide, propylene oxide and their mixtures. Propylene oxide is particularly preferred.

[0104] Preferred starter compounds of the polyether polyol C) are ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, butane-1,3-diol, butane-1,2-diol and butane-2,3-diol. Propylene glycol is particularly preferred.

[0105] The polyol composition comprises at least >0 wt.-%, preferably at least 20 wt.-%, more preferred at least 22 wt.-%, even more preferred at least 24 wt.-% polyether polyol C), based on the total amount of polyols in the polyol composition. The polyol composition comprises at most 68 wt.-%, preferably at most 45 wt.-%, more preferred at most 40 wt.-%, even more preferred at most 35 wt.-% polyether polyol C), based on the total amount of polyols in the polyol composition.

[0106] The polyol composition comprises >0 to 68 wt.-% polyether polyol C), based on the total amount of polyols in the polyol composition. Preferably, the polyol composition comprises 20 to 45 wt- %, more preferred 22 to 40 wt.-%, even more preferred 24 to 35 wt.-% polyether polyol C), based on the total amount of polyols in the polyol composition.

[0107] The polyol composition may additionally comprise polyether polyol D).

[0108] The polyether polyol D) preferably has an OH number of at least >200 mg KOH / g, preferably at least 220 mg KOH / g, more preferred at least 230 mg KOH / g. The polyether polyol D) has an OH number of at most 300 mg KOH / g, preferably at most 280 mg KOH / g, more preferred at most 260 mg KOH / g.

[0109] The polyether polyol D) has an OH number in the range of >200 to 300 mg KOH / g), preferably in the range of 220 to 280 mg KOH / g, more preferred in the range of 230 to 260 mg KOH / g. 240998

[0110] 15

[0111] The polyether polyol D) preferably has a functionality of at least 1.5, more preferred at least 1.7, even more preferred at least 1.8. The polyether polyol D) preferably has a functionality of at most 3.2, more preferred at most 2.5, even more preferred at most 2.1.

[0112] The polyether polyol D) preferably has a functionality in the range of 1.5 to 3.2, more preferred in the range of 1.7 to 2.5, even more preferred in the range of 1.8 to 2.1.

[0113] Possible starter compounds for the polyether polyol D) are, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butane-1,4-diol, butane-1,3-diol, butane-1 ,2-diol, butane-2,3-diol, butane-1,2,4-triol, pentane- 1 ,3,5-triol, glycerol and trimethylolpropane.

[0114] The polyether polyol D) is preferably a reaction product of at least one starter compound that has two active hydrogen atoms with C2 to C4 alkylene oxides. Preferably, all starter compounds of the polyether polyol D) have two active hydrogen atoms. The C2 to C4 alkylene oxides are preferably selected from ethylene oxide, propylene oxide and their mixtures. Propylene oxide is particularly preferred.

[0115] Preferred starter compounds of the polyether polyol D) are ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butane-1 ,4-diol, butane-1,3-diol, butane-1,2-diol and butane-2,3-diol. Propylene glycol, ethylene glycol and 1,4- butanediol are particularly preferred.

[0116] The polyol composition preferably comprises at least >0 wt.-%, more preferred at least 2 wt.-%, even more preferred at least 5 wt.-% polyether polyol D), based on the total amount of polyols in the polyol composition. The polyol composition preferably comprises at most 20 wt.-%, more preferred at most 15 wt.-%, even more preferred at most 12 wt.-%, even more preferred at most 10 wt.-% polyether polyol D), based on the total amount of polyols in the polyol composition.

[0117] The polyol composition preferably comprises 0 to 20 wt.%, more preferred >0 to 20 wt.-%, more preferred 0 to 15 wt.-%, even more preferred 2 to 12 wt.-%, even more preferred 5 to 10 wt.-% polyether polyol D), based on the total amount of polyols in the polyol composition.

[0118] Preferably, the polyol composition comprises 0 to 20 wt.-% polyol D) having an OH number in the range of 200 to 300 mg KOH / g.

[0119] The polyol composition preferably comprises a. 5 to 30 wt.-% polyol A), 240998

[0120] 16 b. 25 to 50 wt.-% polyol B), c. 20 to 45 wt.- % polyol C), and d. 0 to 15 wt.-% polyol D).

[0121] Preferably, the ratio of polyol B) to polyol C) is in the range of 2:1 to 1:2, more preferred in the range of 1.9:1 to 1:1.5, even more preferred in the range of 1.8:1 to 1 :0.8.

[0122] Further isocyanate reactive compounds

[0123] It is possible that the polyol composition comprises further isocyanate reactive compounds in addition to the polyols A) to D). For example, the polyol composition may comprise one or more further isocyanate reactive compounds containing at least two groups that are reactive towards isocyanate. Preferably, the isocyanate reactive groups comprise a reactive hydrogen, e.g. the isocyanate reactive group may be selected from OH-, SH-, NH-, and CH-acid groups.

[0124] Preferably, the further isocyanate reactive compound are polyols. For example, they may be selected from polyether polyols, polyester polyols, polyether ester polyols, and mixtures thereof.

[0125] The polyol composition preferably comprises at most 20 wt.-%, more preferred at most 15 wt.- %, even more preferred at most 10 wt.-%, even more preferred at most 5 wt.-% further isocyanate reactive compounds. Particularly preferably, the polyol component does not comprise further isocyanate reactive compounds except optionally a cell opener. This means that the polyol component particularly preferably does not comprise other polyols than the polyol A), the polyether polyol B), the polyether polyol C) and the polyether polyol D) and optionally a cell opener.

[0126] Catalyst

[0127] The polyol composition comprises at least one catalyst. The catalyst is selected from d1) amine catalysts which have at least one functional group reactive towards isocyanates and / or d2) metal catalysts chosen from carboxylic acid salts of alkali metals, carboxylic acid salts of alkaline earth metals and carboxylic acid salts of ammonium. The functional group reactive toward isocyanates may be an OH, NH or NH2 group. The catalyst is preferably chosen so that it is built in the polyurethane foam and does not generate volatile compounds that would negatively influence the vacuum in the vacuum insulation panel comprising the open-cell rigid polyurethane foam.

[0128] The catalyst may be a single catalyst or a mixture of catalysts. 240998

[0129] 17

[0130] The catalyst is preferably a separate catalyst and is not comprised in any of the polyols A), B), C), or D) or other polyols in the polyol composition.

[0131] Preferably, all catalysts that are used are selected from d1) amine catalysts which have at least one functional group reactive towards isocyanates and d2) metal catalysts chosen from carboxylic acid salts of alkali metals, carboxylic acid salts of alkaline earth metals and carboxylic acid salts of ammonium. Preferably, all catalysts are chosen so that they are built in the polyurethane foam and do not generate volatile compounds that would negatively impact the vacuum in the vacuum insulation panel comprising the open-cell rigid polyurethane foam.

[0132] According to one embodiment, the polyol composition and all components that are used in the preparation of the polyurethane foam are free from catalysts that (i) are not selected from d1) amine catalysts which have at least one functional group reactive towards isocyanates and d2) metal catalysts chosen from carboxylic acid salts of alkali metals, carboxylic acid salts of alkaline earth metals and carboxylic acid salts of ammonium and / or (ii) generate volatile compounds that would negatively influence the vacuum in the vacuum insulation panel comprising the open-cell rigid polyurethane foam.

[0133] Preferred amine catalysts are tertiary amines which bear groups which are reactive toward isocyanate. Some of the most frequently used catalysts are bis(2-dimethylaminoethyl) ether, N , N , N , N , N-pentamethyldiethylenetriamine, N , N , N-triethylaminoethoxyethanol, dimethylcyclohexylamine, dimethylbenzylamine, triethylamine, triethylenediamine, pentamethyldipropylenetriamine, dimethylethanolamine, N-methylimidazole, N-ethylimidazole, tetramethylhexamethylenediamine, tris(dimethylaminopropyl)hexahydrotriazine, dimethylaminopropylamine, N-ethylmorpholine, diazabicycloundecene and diazabicyclononene. Preference is given to using mixtures comprising at least two different tertiary amines as catalysts.

[0134] Preferred metal catalysts chosen from alkali and alkaline earth metal salts of carboxylic acids are potassium acetate, potassium formate, potassium neodecanoate, potassium pivalate and long-chained potassium carboxylates.

[0135] Process for production of open-cell rigid polyurethane foam

[0136] A further aspect of the invention is a process for the production of open-cell rigid polyurethane foam by reacting at least one di- or polyisocyanate with the polyol composition, wherein a blowing agent and a cell opener are present in the reaction. 240998

[0137] 18

[0138] Di- or polyisocyanate

[0139] The at least one di- or polyisocyanate used may include any aliphatic, cycloaliphatic, and aromatic di- or polyfunctional isocyanates known from the prior art and any desired mixture of these. The di- or polyisocyanates can optionally be modified.

[0140] Specific examples include alkylene diisocyanates having 4 to 12 carbon atoms in the alkylene radical, such as dodecane 1 ,12-diisocyanate, 2-ethyltetramethylene 1,4-diisocyanate, 2- methylpentamethylene 1,5-diisocyanate, tetramethylene 1,4-diisocyanate and preferably hexamethylene 1,6-diisocyanate; cycloaliphatic diisocyanates such as cyclohexane 1,3- and 1 ,4-diisocyanate and also any mixtures of these isomers, 1-isocyanato-3,3,5-trimethyl-5- isocyanatomethylcyclohexane (IPDI), hexahydrotolylene 2,4- and 2,6-diisocyanate and also the corresponding isomer mixtures, dicyclohexylmethane 4,4'-, 2,2'- and 2,4'-diisocyanate and also the corresponding isomer mixtures, and preferably aromatic di- and polyisocyanates such as tolylene 2,4- and 2,6-diisocyanate and the corresponding isomer mixtures, methylene diphenyl 4,4'-, 2,4'- and 2,2'-diisocyanate and the corresponding isomer mixtures, mixtures of methylene diphenyl 4,4'- and 2,4'-diisocyanates, polyphenylpolymethylene polyisocyanates, mixtures of methylene diphenyl 4,4'-, 2,4'- and 2,2'-diisocyanates and polyphenylpolymethylene polyisocyanates (polymeric MDI or PM DI) and mixtures of polymeric MDI and tolylene diisocyanates. The di- or polyisocyanates can be used individually or in the form of their mixtures.

[0141] Use is frequently also made of modified polyfunctional isocyanates, i.e. products which are obtained by chemical reaction of organic polyisocyanates. Examples which may be mentioned are polyisocyanates comprising ester, urea, biuret, allophanate, carbodiimide, isocyanurate, uretdione, carbamate and / or urethane groups.

[0142] The polyisocyanates can also be applied in form of prepolymers. These polyisocyanate prepolymers are obtained by reacting the above-described polyisocyanates with compounds having at least two groups reactive towards isocyanate to form a prepolymer.

[0143] Furthermore, prepolymers and mixtures of the above-described isocyanates and prepolymers can be used as the isocyanate (a). These polyisocyanate prepolymers are obtainable by reacting polyisocyanates described above in excess with compounds having at least two groups reactive toward isocyanates to give the prepolymer. The reaction may take place at temperatures of 30 to 100 °C, for example, preferably at about 45 to 60 °C. The prepolymers usually have an NCO content in the range of 14 to 32 wt.-%, preferably in the range of 25 to 30 wt.-%. 240998

[0144] 19

[0145] The compounds having at least two groups reactive towards isocyanate are known and are described in, for example, “Polyurethane Handbook”, Carl Hanser Publishers, 2nd edition 1993, chapter 3.1. For example, polyether polyols and polyester polyols can be applied as compunds having at least two groups reactive towards isocyanate in the preparation of the prepolymers.

[0146] Preferably, the compounds having at least two groups reactive towards isocyanate are polyether polyols and / or polyester polyols containing OH groups deriving from propylene oxide, for example. The polyether polyols and / or polyester polyols preferably have a functionality in the range of 2 to 4, particularly preferably in the range of 2 to 3. Particularly preferably, the compounds having at least two groups reactive towards isocyanate are polyester polyols.

[0147] Preferred di- or polyisocyanates (a) are tolylene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), mixtures of methylene diphenyl diisocyanate and polyphenylpolymethylene polyisocyanates (polymeric MDI or PM DI) and / or related isocyanate prepolymers. Particularly preferably, the at least one di- or polyisocyanate is selected from the group consisting of methylene diphenyl diisocyanate and / or polymeric MDI and / or related isocyanate prepolymers.

[0148] Very particular preference is given to employing polymeric MDI.

[0149] Preferred prepolymers are mixtures of polymeric MDI and polyester polyols. Very particular preference is given to a prepolymer comprising the reaction product of polymeric MDI and a polyester polyol containing monomeric units derived from dicarboxylic acids, fatty acids, and polyfunctional alcohols.

[0150] In one preferred configuration, the prepolymer comprises the reaction product of 92-97 wt.-% of polymeric MDI and 3-8 wt.-% of a polyester polyol containing monomeric units derived from dicarboxylic acids, fatty acids, and polyfunctional alcohols.

[0151] If isocyanate prepolymers are used as isocyanates, the content of compounds having groups which are reactive toward isocyanates is calculated with inclusion of the compounds having groups which are reactive toward isocyanates used for preparing the isocyanate prepolymers.

[0152] Blowing agent

[0153] The blowing agent may be a chemical blowing agent, a physical blowing agent or a mixture of chemical and physical blowing agents. 240998

[0154] 20

[0155] “Chemical blowing agent” is understood to mean compounds that form gaseous products by reaction with isocyanate. Examples of chemical blowing agents are water, acids, in particular formic acid, and mixtures of water and acids. Water is a preferred chemical blowing agent.

[0156] Preferably, the blowing agent comprises water.

[0157] Based on the total weight of all components that are mixed with the at least one di- or polyisocyanate or mixtures thereof, the amount of water is preferably at least 0.5 wt.-%, preferably at least 0.6 wt.-%, more preferred at least 0.7 wt.-%. The amount of water is preferably at most 5 wt.-%, more preferred at most 4 wt.-%, even more preferred at most 3 wt.- %. Preferably, the amount of water is in the range of 0.5 wt.-% to 5 wt.-%, more preferred in the range of 0.6 wt.-% to 4 wt.-%, even more preferred in the range of 0.7 wt.-% to 3 wt.-%.

[0158] The blowing agent may comprise water and at least one further chemical blowing agent. Preferably, the total amount of chemical blowing agents is at least 0.5 wt.-%, more preferably at least 0.6 wt.-%, even more preferably at least 0.7wt.-% based on the total amount of the components that are mixed with the at least one di- or polyisocyanate or mixtures thereof. The total amount of chemical blowing agents is preferably at most 6 wt.-%, more preferably at most 5 wt.-%, even more preferably at most 4 wt.-% based on the total amount of the components that are mixed with the at least one di- or polyisocyanate or mixtures thereof.

[0159] It is particularly preferable that water is the sole chemical blowing agent.

[0160] The blowing agent may comprise water and a physical blowing agent. Suitable physical blowing agents that can be used are in general all hydrocarbons known to those skilled in the art as blowing agents, for example non-halogenated hydrocarbons and halogenated, preferably fluorinated, alkenes.

[0161] Examples of fluorinated alkenes are propenes, butenes, pentenes and hexenes having 3 to 6 fluorine substituents, where other substituents such as chlorine may be present, for example tetrafluoropropenes, fluorochloropropenes, for example trifluoromonochloropropenes, pentafluoropropenes, fluorochlorobunetes, hexafluorobutenes or mixtures thereof. Preference is given to 1 ,1,1,3-tetrafluoropropene, 1 ,1,1-trifluoro-2-chloropropene, 1-chloro-3,3,3- trifluoropropene, 1,1 ,1 ,2,3-pentafluoropropene, Z-1 ,1 ,1,4,4,4-hexafluoro-2-butene, E- 1 ,1 ,1,4,4,4-hexafluoro-2-butene, 1 -brompentafluoropropene, 2-brompentafluoropropene, 3- brompentafluoropropene, 1,1,2,3,3,4,4-heptafluoro-1-butene, 1 -chloro-2, 3,3,3- tetrafluoropropene, 1-brom-2,3,3,3-tetrafluoropropene, 2-brom-1,3,3,3-tetrafluoropropene, 3- brom-1 ,1 ,3,3-tetrafluoropropene, 2-brom-3,3,3-trifluoropropene, E-1-brom-3,3,3- 240998

[0162] 21 trifluoropropene, 3,3,3-trifluoro-2-(trifluoromethyl)propene, 1,1,1-trifluoro-2-butene and / or mixtures thereof.

[0163] Examples of non-halogenated hydrocarbon blowing agents are acyclic pentane isomers and / or cyclopentane, especially cyclopentane. Preference is given to using acyclic pentane isomers and / or cyclopentane. Preference is given to cyclopentane and mixtures of cyclopentane with isopentane having a content of at least 70 wt.-% of cyclopentane; particular preference is given to using cyclopentane having a purity of at least 90% by weight, especially of at least 95% by weight.

[0164] In a preferred embodiment, the amount of the physical blowing agent is in the range of >0 to 35 wt.-%, more preferred from 1 to 20 wt.-% based on the components that are mixed with the at least one di- or polyisocyanate or mixtures thereof.

[0165] The blowing agent preferably comprises water and a physical blowing agent. The physical blowing agent is preferably selected from acyclic pentane isomers, cyclopentane, mixtures of cyclopentane with isopentane having a content of at least 70 wt.-% of cyclopentane, and cyclopentane having a purity of at least 90 wt.-%. Particularly preferably, the blowing agent comprises water and a mixture of cyclopentane with isopentane having a content of 70 wt.-% of cyclopentane.

[0166] The blowing agent may be partly or completely mixed with the polyol composition prior to the reaction with the polyisocyanate. If both chemical and physical blowing agents are used, it is possible that the chemical blowing agent is mixed with the polyol composition prior to the reaction with the polyisocyanate while the physical blowing agent is not.

[0167] Cell opener

[0168] Cell openers, also called cell opening agents, are used to increase the number of open cells. These are preferably compounds which influence the surface tension of the components during the foaming. One cell opener or a mixture of cell openers can be used.

[0169] Examples of cell openers may be selected from macromolecular compounds or mixtures of macromolecular compounds based at least partially on saturated or unsaturated hydrocarbons or siloxane motifs; esters, preferably esters of a carboxylic acid, in combination with macromolecular, unsaturated hydrocarbons; polyester polyols containing surfactant motifs; polyester polyols containing monomeric units derived from a dicarboxylic acid, a fatty acid, and a polyfunctional alcohol; and / or prepolymers comprising a polyisocyanate and a polyester polyol 240998

[0170] 22 containing surfactant motifs, preferably prepolymers comprising a polyisocyanate and a polyester polyol containing monomeric units derived from a dicarboxylic acid, a fatty acid, and a polyfunctional alcohol.

[0171] Preferably, the cell opener is selected from esters of a carboxylic acid in combination with macromolecular, unsaturated hydrocarbons, and mixtures of macromolecular unsaturated hydrocarbons with a phthalic ester.

[0172] The cell opener may be added into the polyol composition, or to the isocyanate composition comprising the polyisocyanate. If the cell opener is a prepolymer which is used as the polyisocyanate in the reaction as defined below, said polyisocyanate can take over the function of the cell opener (c), and thus no additional cell opener needs to be applied in this case.

[0173] Further auxiliaries and / or additives

[0174] Further auxiliaries and / or additives can optionally be added to the reaction mixture for producing the rigid polyurethane foams. Examples are foam stabilizers, surface-active substances, antioxidants, chain extenders, cross linkers, cell regulators, fillers, dyes, pigments, hydrolysis inhibitors, fungistatic and bacteriostatic substances.

[0175] The auxiliaries and / or additives are preferably chosen so that they do not create volatile compounds that would negatively impact the vacuum in the vacuum insulation panel comprising the open-cell rigid polyurethane foam.

[0176] In a preferred embodiment, the auxiliaries and / or additives must be chosen so that they do not create volatile compounds that would worsen the vacuum in the vacuum insulation panel comprising the open-cell rigid polyurethane foam.

[0177] Foam stabilizers are added to stabilize the polyurethane foam. Foam stabilizers are materials which promote formation of a regular cell structure during foaming and are also called surfactants hereinafter. Examples are silicone-comprising foam stabilizers, also called silicon surfactants, such as siloxaneoxalkylene copolymers and other organopolysiloxanes. Further examples include alkoxylation products of fatty alcohols, oxo alcohols, fatty amines, alkylphenols, dialkylphenols, alkylcresoles, alkylresorcinol, naphthol, alkylnaphthol, naphthylamine, aniline, alkylaniline, toluidine, bisphenol A, alkylated bisphenol A, polyvinyl alcohol and also alkoxylation products of condensation products of formaldehyde and alkylphenols, formaldehyde and dialkylphenols, formaldehyde and alkylcresoles, formaldehyde and alkylresorcinol, formaldehyde and aniline, formaldehyde and toluidine, formaldehyde and 240998

[0178] 23 naphthol, formaldehyde and alkylnaphthol and also formaldehyde and bisphenol A or mixtures of two or more of these foam stabilizers.

[0179] Preferably, at least one foam stabilizer is used in the preparation of the open-cell rigid polyurethane foam.

[0180] Based on the total weight of all components that are mixed with the at least one di- or polyisocyanate or mixtures thereof, the amount of foam stabilizer is preferably in the range of 0 to 5 wt.-%, more preferred in the range of 0.2 to 4 wt.-% even more preferred in the range of 0.4 to 2 wt.-%, based on the amount of the components that are mixed with the at least one di- or polyisocyanate or mixtures thereof.

[0181] Chain extenders and cross linkers have usually a molecular weight between 60 g / mol to 300 g / mol. Bifunctional chain extenders and the trifunctional and higher-functional cross linkers or, if appropriate, mixtures thereof might be added. Chain extenders and / or cross linkers used are preferably alkanol amines and in particular diols and / or triols having molecular weights preferably between 60 g / mol to 300 g / mol.

[0182] More detailed information regarding the starting materials, blowing agents, catalysts and auxiliaries and / or additives used to carry out the process according to the invention can be found, for example, in the “Polyurethane Handbook”, Carl Hanser Publishers, 2nd edition 1993.

[0183] In a preferred embodiment, the polyol composition, the at least one blowing agent, the at least one cell opener, optionally the at least one foam stabilizer as well as other additives and / or auxiliaries, if present, are mixed together to form a polyol component. It is also possible that the above-mentioned components except a physical blowing agent are mixed together to form a polyol component. The polyol component is then reacted with the di- or polyisocyanate or mixtures thereof and, if appropriate, optionally blowing agents. Such a two-component process has proven to be particularly advantageous.

[0184] When producing the open-cell rigid polyurethane foam, the polyisocyanate and the polyol composition are preferably reacted at an isocyanate index of at least 150, more preferred at least 160, particularly preferred at least 180. The open-cell rigid polyurethane foam preferably has an isocyanate index of at most 300, more preferred at most 250, even more preferred at most 220.

[0185] When producing the open-cell rigid polyurethane foam, the polyisocyanate and the polyol composition as well as the other isocyanate reactive compounds are preferably reacted at an isocyanate index in the range of 150 to 300, more preferred in the range of 160 to 250, even more preferred in the range of 180 to 220.

[0186] The isocyanate index is the ratio of isocyanate groups to isocyanate-reactive groups multiplied by 100. An isocyanate index of 100 corresponds to an equimolar ratio of the isocyanate groups used and isocyanate reactive groups used.

[0187] The reaction mixture is preferably prepared by mechanically mixing the components, preferably in a high-pressure mixing head. Preferably, the mixing head operates in an automated fashion.

[0188] The process for the production of the open-cell rigid polyurethane foam is preferably a discontinuous process. The open-cell rigid polyurethane foam is preferably a block foam.

[0189] A further aspect of the invention is an open-cell rigid polyurethane foam obtainable by the above-described process.

[0190] A further aspect of the invention is an open-cell rigid polyurethane foam for use in vacuum insulation panels having a recycled content in the range of 0.5 to 10 wt.-%, based on the weight of the foam. The open-cell rigid polyurethane foam is preferably obtained by the process described above. Preferably, the open-cell ridig polyurethane foam is obtained by reactinv at least one polyisocyanate with the polyol composition according to the invention, wherein at least one blowing agent and at least one cell opener is present in the reaction.

[0191] The open-cell rigid polyurethane foam preferably has a gel time in the range of >180 s to 400 s, more preferred in the range of >150 s to 350 s, particularly preferred in the range of >100 s to 300 s,

[0192] The open-cell rigid polyurethane foam preferably has a core density of at least 30 kg / m3, more preferred at least 40 kg / m3, even more preferred at least 45 kg / m3. The maximal overall density of the open-cell rigid polyurethane foam is 100 kg / m3, more preferred 90 kg / m3, even more preferred 80 kg / m3. Preferably, the open-cell rigid polyurethane foam has an overall density in the range of 30 to 100 kg / m3, more preferred 40 to 90 kg / m3, and in particular 45 to 80 kg / m3. The density is determined by determining the weight of a cube cut out from a foam block and having an edge length of at least 10 cm in accordance with DIN EN ISO 845.

[0193] The open-cell rigid polyurethane foam preferably has a recycled content of at least 0.5 wt.-%, more preferred at least 1 wt.-%, based on the weight of the foam. The open cell rigid 25 polyurethane foam preferably has a recycled content of at most 10 wt.-%, more preferred at most 8 wt.-%, even more preferred at most 5 wt.-%, based on the weight of the foam.

[0194] The open-cell rigid polyurethane foam is preferably suitable for use in vacuum insulation panels.

[0195] The open-cell rigid polyurethane foam preferably has a recycled content in the range of 0.5 to 10 wt.-%, more preferred 1 to 8 wt.-%, particularly preferred 1 to 5 wt.-%, based on the weight of the foam.

[0196] The open-cell rigid polyurethane foam preferably has a thermal conductivity below 8 mW / m*K, more preferred below 7 mW / m*K, even more preferred below 6 mW / nTK in an evacuated state. Evacuated state means a pressure of 0.05 bar or less. Evacuated state means that the opencell rigid polyurethane foam is enveloped with a gas-impermeable film and evacuated.

[0197] One aspect of the invention is the use of the open-cell rigid polyurethane foam as a core material in vacuum insulation panels.

[0198] The vacuum insulation panels are produced by enveloping the open-cell rigid polyurethane foam with a gas-impermeable film, closing it e.g. by welding, and evacuating it.

[0199] The vacuum insulation panels comprising the open-cell rigid polyurethane foam as core material preferably have a pressure increase of the initial vacuum of at most 100 %, more preferred at most 50 %, even more preferred at most 25 % after 7 days storage at 23 °C, 1 bar and 50 % humidity and an initial vacuum of 0.05 bar or less, more preferred of 10 mbar or less, even more preferred of 0.1 mbar or less. Initial vacuum means the pressure of the vacuum insulation panels measured within 0 to 6 hours after the preparation of the vacuum insulation panels.

[0200] Preferably, the vacuum insulation panels comprising the open-cell rigid polyurethane foam have a thermal conductivity below 8 mW / m*K, more preferred below 7 mW / m*K, even more preferred below 6 mW / nTK in an evacuated state. Evacuated state means a pressure of 0.05 bar or less.

[0201] Experimental part

[0202] The present invention is intended to be illustrated by the following examples, the examples being intended only to illustrate certain aspects of the invention and in no way to be regarded as limiting the scope of the invention. 240998

[0203] 26

[0204] Analytical methods

[0205] Measurement of hydroxyl number:

[0206] Hydroxyl numbers are determined according to DIN 53240 (1971-12).

[0207] Core density:

[0208] The core density was determined by measuring the foam density in the core in accordance with DIN EN ISO 845.

[0209] Start time: The start time refers to the time at which the polyurethane foam begins to expand after the components are mixed together. It is the point at which the chemical reaction starts and the foam begins to rise.

[0210] Rise time: The rise time refers to the duration it takes for the polyurethane foam to fully expand and rise to its maximum height. It is the time it takes for the foam to reach its desired level of expansion and stability.

[0211] Gel time:

[0212] Time from the commencement of mixing of the reaction mixture up to the time until it is possible to draw threads in contact with the foam (for example with a wooden rod). This point thus represents the transition from a liquid to a solid state.

[0213] Open cell content and measurement time:

[0214] The determination of the open cell content with corresponding measurement time was obtained in accordance with DIN EN ISO 4590.

[0215] Hardening:

[0216] For the determination of the core hardening of the foam, the polyol component and the isocyanate were weighed into a 1100mL PE beaker at a predetermined mixing ratio so that the total weight is 120g. The mixture was then stirred at 1800 rpm for 20 seconds. After 5 minutes, the beaker cap was cut off and placed under the bolt of the Zwick Z 2.5. The bolt was then driven as close as possible to the foam core. The measurement was started after 5.5 minutes. A pre-load of 1 N was applied and held when reached. The first measurement was carried out after 6 minutes. The bolt was driven 5mm into the foam core with a speed of 50mm / min and recorded the applied force. Subsequently, the bolt as returned to its starting position so that further measurements could follow. These took place after 7min, 8min, 9min, 10min, 11 min. Between the individual measurements, the beaker was rotated so that different points were pressed into the foam. 240998

[0217] 27

[0218] Compressive strength:

[0219] Compressive strength is determined according to DIN ISO 844 EN DE (2014-11).

[0220] Thermal conductivity:

[0221] The thermal conductivity was measured according to DIN EN 12667 on a TAURUS TCA 300 DTX at an average temperature of 10 °C. Three samples with a size of 300 x 300 x 30 mm3were tested.

[0222] Materials

[0223] Polyol 1 : The glycolysis was carried out in a temperature-controlled 2-liter glass reaction vessel with a thermostatic jacket equipped with a stirrer, reflux condenser and dosing funnel in a nitrogen atmosphere. 800 g of diethylene glycol were heated to 210°C. To this mixture, 800 g of PUR foam powder (Produced from Balindur 2700 / 3A / IP from BASF Polyurethanes) was added in several portions, waiting after each addition until the particles had completely decomposed. The reaction mixture was then cooled to 100°C and 192 g of 2-ethylhexylglycidyl ether was added. After a post-reaction time of 30 minutes at 100°C, a recycled polyol with the following characteristics was obtained:

[0224] OH number: 489 mg KOH / g,

[0225] Viscosity: 14040 mPas@ 25 °C, Residual 4,4'-MDA: 100 ppm.

[0226] Polyol 2: The glycolysis was carried out in a temperature-controlled 2-liter glass reaction vessel with a thermostatic jacket equipped with a stirrer, reflux condenser and dosing funnel in a nitrogen atmosphere. 1000 g of diethylene glycol were heated to 210°C. To this mixture, 760 g of PUR foam powder (Produced from Balindur 2700 / 3 / VIP from BASF Polyurethanes) was added in several portions, waiting after each addition until the particles had completely decomposed. The reaction mixture was then cooled to 100°C and 240 g of 2-ethylhexylglycidyl ether was added. After a post-reaction time of 30 minutes at 100°C, a recycled polyol with the following characteristics was obtained:

[0227] OH number: 549 mg KOH / g,

[0228] Viscosity: 5344 mPas@ 25 °C, Residual 4,4'-MDA: 200 ppm.

[0229] Polyol 3: Polyether polyol based on propylene glycol and propylene oxide; functionality 1.98, OH number 104 240998

[0230] 28

[0231] Polyol 4: Polyether polyol based on saccharose, glycerin and propylene oxide; functionality

[0232] 4.34, OH number 490

[0233] Polyol 5: Polyether polyol based on propylene glycol and propylene oxide; functionality 1.99, OH number 248

[0234] Catalyst 1 : Potassium acetate in MEG, 47% by weight

[0235] Catalyst 2: Dimethylamino)propylamine (DMAPA)

[0236] Chain extender: Mono ethylene glycol

[0237] Stabilizer: Polydimethylsiloxane-polyether copolymer

[0238] Cell opener 1: Composition based on unsaturated hydrocarbons, phthalic acid ester

[0239] Cell opener 2: Polysiloxane

[0240] Blowing agent: Cyclopentane 70; a mixture of cyclopentane and isopentane, mixing ratio 70:30 by weight

[0241] Isocyanate: Polymer MDI having a viscosity of 210 mPas at 25 °C

[0242] The components other than isocyanate were mixed to give a polyol component and reacted with the isocyanate. The amounts of the feedstocks used can be found in tablel . CE denotes comparative examples, E inventive examples. E1-E3 as well as CE1-CE3 were laboratory examples; E4, E5 and CE4 machine runs.

[0243] In machine runs, mixing was done in a mixing head. Machine settings were as follows: Krauss Maffei 16 / 40, 220g / s-900 s / s discharge capacity, 140 bar pressure at the mixing head (MT18-2 company Hennecke), component temperature 20°C.

[0244] Table 1. Laboratory examples 240998

[0245] 29

[0246] Table 2. Machine examples

Claims

24099830Claims1 . A polyol composition comprising a) 1 to 30 wt.-% polyol A), wherein the polyol A) is a recycled polyol obtained by depolymerization of a polyurethane foam, b) 30 to 75 wt.-% polyether polyol B) having a functionality in the range of 3.5 to 8, wherein at least one starter compound of the polyether polyol P1) is a monosaccharide, oligosaccharide, polysaccharide, and / or a sugar alcohol and has at least 4 active hydrogen atoms; c) >0 to 68 wt.-% polyether polyol C) having an OH number in the range of 20 to 200 mg KOH / g) and being a reaction product of starter compounds with at least two alkylene oxide reactive hydrogen atoms with alkylene oxides, and d) an amine catalyst d1 ) which has at least one functional group reactive towards isocyanates and / or a metal catalyst d2) chosen from carboxylic acid salts of alkali metals, carboxylic acid salts of alkaline earth metals and carboxylic acid salts of ammonium, wherein the amounts of the polyols are based on the total amount of polyols in the polyol composition.

2. The polyol composition according to claim 1 , wherein the polyurethane foam is an open-cell rigid polyurethane foam.

3. The polyol composition according to any of claims 1 to 2, wherein the polyol A) contains less than 1 wt.-% tertiary amines, wherein the tertiary amines do not have functional groups that are reactive towards isocyanates and have a vapor pressure above 0.1 bar at 20 °C, the amount of the tertiary amines being based on the weight of the polyol A).

4. The polyol composition according to any of claims 1 to 3, wherein the polyol A) has an OH number in the range of 300 to 600 mg KOH / g.

5. The polyol composition according to any of claims 1 to 4, wherein the polyol A) has a functionality in the range of 2 to 6.

6. The polyol composition according to any of claims 1 to 5, wherein the polyol A) has an acid number lower than 10 mg KOH / g.

7. The polyol composition according to any of claims 1 to 6, wherein the polyol A) has an amine number lower than 100 mg KOH / g.

8. The polyol composition according to any of claims 1 to 7, wherein the polyol A) has a methylenediamine concentration below 2500 ppm, based on the weight of the polyol A).240998319. The polyol composition according to any of claims 1 to 8, wherein the polyol composition comprises 0-20 wt.-% polyol D) having an OH number in the range of >200 to 300 mg KOH / g.

10. The polyol composition according to claim 9, wherein the polyol composition comprises a. 5 to 30 wt.-% polyol A), b. 25 to 50 wt.-% polyol B), c. 20 to 45 wt.-% polyol C), and d. 0 to 15 wt.-% polyol D).11 . A process for the production of open-cell rigid polyurethane foam by reacting at least one polyisocyanate with the polyol composition according to any of claims 1 to 10, wherein at least one blowing agent and at least one cell opener is present in the reaction.

12. The process according to claim 11 , wherein the polyisocyanate and the polyol composition are reacted at an isocyanate index in the range of 150-300.

13. An open-cell rigid polyurethane foam obtainable by the process of claim 11 or 12.

14. An open-cell rigid polyurethane foam for use in vacuum insulation panels having a recycled content in the range of 0.5 to 10 wt.-%, based on the weight of the foam.

15. The use of the open-cell rigid polyurethane foam produced by the process of claim 11 or 12 or of the open-cell rigid polyurethane foam according to any of claims 13 to 14 as a core material of vacuum insulation panels.

16. A vacuum insulation panel comprising the open-cell rigid polyurethane foam prepared according to the process of claim 11 or 12 or the open-cell rigid polyurethane foam according any of claims 13 to 14 as core material.

17. The vacuum insulation panel according to claim 16, wherein the vacuum insulation panel has a pressure increase of the initial vacuum of at most 100 % after 7 days storage at 23 °C, 1 bar and 50 % humidity and an initial vacuum of 0.05 bar or less.

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