Polyurethane insulating foam and production thereof

Abstract

A process for producing PU foams, especially rigid PU foams, based on a foamable reaction mixture which contains polyisocyanate, compound having reactive hydrogen atoms, blowing agent, foam stabilizer and, if present, further additives, is described, wherein in addition a specific perfluoropolyether is used.

Description

[0001] This invention pertains to the field of rigid polyurethane foam. More specifically, this invention relates to the production of rigid polyurethane foam using specific perfluoropolyethers, and further relates to the uses of foams produced therefrom.

[0002] The production of polyurethane foam by foaming a foamable reaction mixture is currently a large-scale industrial operation, based on isocyanates, compounds with reactive hydrogen atoms, blowing agents, stabilizers, and other additives, if present. For this purpose, all components except the isocyanate are typically pre-formulated to obtain a processable mixture, which is then mixed with the isocyanate in a foaming apparatus. Foam formation and addition polymerization reactions occur simultaneously in the initial liquid reaction mixture until the composition cures to obtain the desired foam.

[0003] To prepare thermosetting insulating foam, for example, to prepare foam with <60 kg / m³ 3 A relatively low foam density and a maximum number of small closed cells (high cell density) of rigid foam would be desirable. In this case, the cells should preferably be evenly distributed throughout the molded part, that is, they should not exhibit a gradient.

[0004] A foaming gas is necessary for the formation of this foam. This can be produced, for example, by the reaction of isocyanate with water, or by the addition of CO2 and / or a low-boiling-point organic liquid.

[0005] For completeness, it should be mentioned that, in addition to foam formation during the polymerization reaction, as described herein for polyurethane formation, foam formation can also occur during extrusion. However, these extrusion methods should, in principle, differ from the polyurethane foam methods described herein. For example, WO 2002 / 034823 describes an extrusion method for thermoplastics that results in the formation of multi-peak thermoplastic polymer foams. Conversely, non-thermoplastic polyurethane foam systems, which are preferred in the present case rather than thermosetting polyurethane foam systems, are preferably characterized by a generally uniform unimodal cell size distribution and cannot be obtained by extrusion methods.

[0006] Rigid polyurethane and polyisocyanurate foams are typically produced using cell-stabilizing additives to ensure a uniform and low-defect foam structure with fine cells, thus having a substantially positive impact on the performance characteristics of rigid foams, particularly their thermal insulation properties. Surfactants based on polyether-modified siloxanes are particularly effective and therefore represent a preferred type of foam stabilizer.

[0007] EP1544235 describes typical polyether-modified siloxanes for rigid PU foam applications. Siloxanes with 60 to 130 silicon atoms and various polyether substituents R are used here, with a mixed molar mass of 450 to 1000 g / mol and an ethylene oxide content of 70 to 100 mol%. Although these compounds affect the fineness and regularity of the cell structure to some extent, there are limitations on the fine cell content beyond which further increases in stabilizer concentration cannot achieve the associated improvements in cell refinement and thermal insulation.

[0008] In addition, existing technologies envision other options for positively influencing the thermal insulation properties of rigid foams. For example, EP0551636A1 describes a method for producing rigid polyurethane foam by reacting a polyisocyanate with at least one relatively high molecular weight compound having at least two reactive hydrogen atoms in the presence of a blowing agent and a catalyst, wherein the blowing agent used is a mixture comprising 5% to 40% by weight of at least one highly fluorinated and / or perfluorinated organic compound and 30% to 95% by weight of cyclopentane. According to the statements therein, the method aims to achieve a lower thermal conductivity.

[0009] EP1553129A1 describes a method for producing rigid polyurethane foam, comprising producing a polyol mixture from a polyol and a nucleating agent, and reacting the polyol mixture with a polyisocyanate. The production of the polyol mixture includes emulsifying the nucleating agent with a portion or all of the polyol. The nucleating agent may contain a perfluorinated olefin having at least six carbon atoms. According to the statements therein, the method aims to achieve improved thermal insulation properties.

[0010] However, there remains a need for options that can provide improved thermal insulation properties from polyurethane foams. This corresponds to the objective of this invention.

[0011] Surprisingly, it has now been discovered, as will be precisely described below, that the use of specific perfluoropolyethers can provide rigid polyurethane foams with improved thermal insulation properties.

[0012] In view of this background, the present invention provides a composition for producing rigid polyurethane foam, the composition comprising at least one isocyanate component, a polyol component, an optional catalyst for catalyzing the formation of urethane or isocyanurate bonds, an optional blowing agent, and an optional foam stabilizer, wherein the composition further comprises at least one perfluoropolyether comprising a linear structure of formula (a) and / or a cyclic structure of formula (b):

[0013]

[0014] in

[0015] a = 1 to 5, preferably 1 to 3

[0016] R1 and R5 are independently -CF3, -C2F5, -C3F7, -C4F9, -CF2H, -C2F4H, -C3F6H, or -C4F8H, wherein the group having 3 or 4 carbon atoms can be linear or branched, preferably -CF3, -C2F5, or -CF2H.

[0017] R2, R3, and R4 are independently -F or -CF3, preferably all groups R2, R3, and R4 = -F, or one of groups R2, R3, and R4 is -CF3 and the other two are -F.

[0018] The condition is that if a > 1, then in each case, different groups R2, R3, and R4 as defined above are possible for each repeating unit.

[0019] as well as

[0020]

[0021] Where a = 1 to 4, preferably 1 to 2, particularly preferably 1, and R2, R3 and R4 are as defined in equation (a).

[0022] In the context of this invention, perfluoropolyethers are correspondingly oligomeric perfluoroethers or perfluorinated oligomers of the corresponding alkoxides. In the context of this invention, perfluoropolyethers according to the invention comprise at least one structure of formula (a) and / or (b) above, especially mixtures of these structures, i.e., for example, mixtures of multiple structures of formula (a), mixtures of multiple structures of formula (b), or mixtures of multiple structures of formulas (a) and (b).

[0023] This invention offers numerous advantages. The resulting PU foam exhibits improved thermal insulation compared to corresponding foams without the perfluoropolyether used according to the invention. This improved thermal insulation is observed in both the initial and aged states of the foam. All other application-related foam properties are only negligibly affected (if any) by the perfluoropolyether used according to the invention. No changes, or at most negligible changes, are observed even in cases where the surface quality of the foam test samples is quite sensitive.

[0024] In the context of this invention, polyurethane (PU) should be understood in particular as a product obtained by reacting polyisocyanates with polyols or compounds having isocyanate reactive groups. Other functional groups besides polyurethane can also be formed in the reaction, examples of which are isocyanate dimers, carbodiimides, isocyanurates, urethane, biuret, urea, and / or ureaketene imides. Therefore, in the context of this invention, PU is understood to refer to polyurethane and the reaction products of polyisocyanates, polyureas, and polyisocyanates containing isocyanate dimer, carbodiimide, urethane, biuret, and ureaketene imide groups. In the context of this invention, polyurethane foam (PU foam) is particularly understood to refer to foam obtained as a reaction product based on polyisocyanates and polyols or compounds having isocyanate reactive groups. Other functional groups besides the eponymous polyurethane can be formed, examples of which are urethane, biuret, urea, carbodiimide, isocyanate dimers, isocyanurates, or ureaketene imides. In the context of this invention, the term PU foam also includes so-called polyurethane foam moldings, particularly rigid polyurethane foam moldings.

[0025] In a preferred embodiment of the invention, the preferred composition according to the invention has the following characteristic: the linear structure of formula (a) comprises at least one structure selected from the following groups (i) to (vii):

[0026] (Structure i) 1,1,1,2,3,3-hexafluoro-2,3-bis(pentafluoroethoxy)propane

[0027]

[0028] (Structure ii) 1,1,1,2,3,3-Hexafluoro-3-(pentafluoroethoxy)-2-(trifluoromethoxy)propane

[0029]

[0030] (Structure iii) 1,1,1,2,3,3-Hexafluoro-2-(pentafluoroethoxy)-3-(trifluoromethoxy)propane

[0031]

[0032] (Structure iv) 2-(difluoromethoxy)-1,1,1,2,3,3-hexafluoro-3-(pentafluoroethoxy)propane

[0033]

[0034] (Structure v) 1-(difluoromethoxy)-1,1,2,3,3,3-hexafluoro-2-(pentafluoroethoxy)propane

[0035]

[0036] (Structure vi) 1,1,1,2,3,3-Hexafluoro-3-{[1,1,1,2,3,3-Hexafluoro-3-(trifluoromethoxy)propane-2-yl]oxy}-2-(trifluoromethoxy)propane

[0037]

[0038] (Structure vii) 1,1,1,3,3,4,6,6,7,9,9,10,12,12,12-pentadecano-4,7,10-tris(trifluoromethyl)-2,5,8,11-tetraoxadodecane

[0039]

[0040] Preferably, in the composition according to the invention, at least two of structures (i) to (vii) are present, more preferably at least three, still more preferably at least four, even more preferably at least five, and still more preferably six, especially all of them.

[0041] Preferred combinations include at least structures (i) and (ii) or at least (i) and (iii), or at least (i) and (iv), or at least (i) and (v), or at least (i) and (vi) or at least (i) and (vii), or at least (ii) and (iii) or at least (ii) and (iv), or at least (ii) and (v), or at least (ii) and (vi) or at least (ii) and (vii), or at least (iii) and (iv), or at least (iii) and (v), or at least (iii) and (vi) or at least (iii) and (vii), or at least (iv) and (v), or at least (iv) and (vi) or at least (iv) and (vii), or at least (v) and (vi) or at least (v) and (vii), or at least (vi) and (vii).

[0042] Further preferred combinations include at least structures (i), (ii), and (iii), or at least (i), (ii), and (iv), or at least (i), (ii), and (v), or at least (i), (ii), and (vi), or at least (i), (ii), and (vii), or at least (i), (iii), and (iv), or at least (i), (iii), and (v), or at least (i), (iii), and (vii), or at least (i), (iv), and (v), or at least (i), (iv), and (vi), or at least (i), (iv), and (vii), or at least (i), (v), and (vi), or at least (i), (v), and (vi), or at least (i), (v), and (vi), or at least (i), (v), and (vi). ) and (vii), or at least (i), (vi) and (vii), or at least (ii), (iii) and (iv), or at least (ii), (iii) and (v), or at least (ii), (iii) and (vi), or at least (ii), (iii) and (vii), or at least (ii), (iv) and (v), or at least (ii), (iv) and (vii), or at least (ii), (iv) and (vii), or at least (iii), (iv) and (v), or at least (iii), (v) and (vii), or at least (iii), (v) and (vii), or at least (iv), (v) and (vii), or at least (iv), (v) and (vii).

[0043] In the context of the preferred embodiment, the composition according to the invention has the following characteristic: as a cyclic structure of formula (b), at least 2,2,3,5,5,6-hexafluoro-3,6-bis(trifluoromethyl)-1,4-dioxane is present.

[0044]

[0045] The compositions according to the invention containing a linear structure of formula (a) and a cyclic structure of formula (b) are particularly preferred.

[0046] Preferably, at least one of structure (viii) and other structures (i) to (vii), more preferably two or three of other structures (i) to (vii), are present in the composition according to the invention.

[0047] In each case, the preferred combination, in addition to structure (viii), includes at least structures (i) and (ii), or at least (i) and (iii), or at least (i) and (iv), or at least (i) and (v), or at least (i) and (vi), or at least (i) and (vii), or at least (ii) and (iii), or at least (ii) and (iv), or at least (ii) and (v), or at least (ii) and (vi) or At least there are (ii) and (vii), or at least there are (iii) and (iv), or at least there are (iii) and (v), or at least there are (iii) and (vi), or at least there are (iii) and (vii), or at least there are (iv) and (v), or at least there are (iv) and (vi), or at least there are (iv) and (vii), or at least there are (v) and (vii), or at least there are (v) and (vii).

[0048] Further preferred combinations, in each case, in addition to structure (viii), include at least structures (i), (ii), and (iii), or at least (i), (ii), and (iv), or at least (i), (ii), and (v), or at least (i), (ii), and (vi), or at least (i), (ii), and (vii), or at least (i), (iii), and (iv), or at least (i), (iii), and (v), or at least (i), (iii), and (vii), or at least (i), (iv), and (v), or at least (i), (iv), and (vii), or at least (i), (iv), and (vii), or at least (i), (iv), and (vii), or at least (i), (v), and (vii), or at least (i), (v), and (vi), or at least (i), (v), and (vii), or at least (i), (v), and (vi), or At least there are (i), (v) and (vii), or at least there are (i), (vi) and (vii), or at least there are (ii), (iii) and (iv), or at least there are (ii), (iii) and (v), or at least there are (ii), (iii) and (vi), or at least there are (ii), (iv) and (v), or at least there are (ii), (iv) and (vii), or at least there are (ii), (iv) and (vii), or at least there are (iii), (iv) and (v), or at least there are (iii), (v) and (vii), or at least there are (iii), (v) and (vii), or at least there are (iv), (v) and (vii), or at least there are (iv), (v) and (vii).

[0049] More preferably, structure (viii) and at least four of the other structures (i) to (vii), more preferably at least five of the other structures (i) to (vii), and even more preferably at least six of the other structures (i) to (vii), particularly all of structures (i) to (vii) are present in the composition according to the invention. Therefore, a particularly preferred composition according to the invention comprises all eight structures (i) to (viii).

[0050] In a particularly preferred embodiment of the invention, the composition according to the invention is characterized in that the present perfluoropolyether, as a whole, comprises at least 25% by weight, preferably at least 50% by weight, more preferably at least 75% by weight, and particularly at least 90% by weight of those perfluoropolyethers as defined in formulas (a) and (b), particularly those corresponding to structures (i) to (viii).

[0051] This is a particularly preferred embodiment of the invention when the perfluoropolyether is used as a whole in a total amount of 0.01 to 15 parts, preferably 0.1 to 10 parts, and particularly preferably 0.1 to 5 parts (based on 100 parts of polyol). A suitable lower limit within the range of preferred embodiments may also be 0.3 parts, 0.5 parts, or 1 part of perfluoropolyether (based on 100 parts of polyol).

[0052] The perfluoropolyethers used in this invention and their preparation are known in themselves. Relevant examples can be found, in particular, in WO2019 / 202079 A1, WO2019 / 202076 A1 or WO2018 / 108864 A1 and the sources cited therein.

[0053] The compositions according to the invention used for preparing rigid polyurethane foams can be used in all known methods to prepare the corresponding rigid polyurethane foams.

[0054] The present invention further provides a method for producing rigid PU foam based on a foamable reaction mixture comprising a polyisocyanate, a compound having reactive hydrogen atoms, a blowing agent, a foam stabilizer, and other additives that may be present, wherein a perfluoropolyether according to the present invention and as described above is also used. Regarding the perfluoropolyether according to the present invention, reference is made explicitly to the above description in this regard to avoid repetition.

[0055] Therefore, the present invention further provides rigid PU foam produced by the above method.

[0056] In a preferred embodiment of the invention, the rigid polyurethane foam has a strength of 5 to 900 kg / m³. 3 Preferred weight is 8 to 800 kg / m³ 3 Especially preferred is 10 to 600 kg / m3 Especially 20 to 150 kg / m 3 The density of the foam.

[0057] The efficacy of the perfluoropolyether used according to the invention is advantageously independent of the polyurethane or polyisocyanurate base formulation; that is, the perfluoropolyether used according to the invention can be used to improve the thermal insulation properties in a wide range of polyurethane or polyisocyanurate formulations. The reduction in thermal conductivity achieved by using the perfluoropolyether according to the invention can be observed in two types of formulations: formulations that have been thoroughly optimized for low thermal conductivity using methods known to those skilled in the art, corresponding to current prior art for use as insulating foams, and formulations that have been optimized for other foam properties and have not yet shown optimal thermal conductivity achievable by prior art.

[0058] The rigid PU foam according to the invention preferably has a thermal conductivity of less than or equal to 25 mW / m*K, which can be further significantly reduced by optionally adding other additives and auxiliaries known to those skilled in the art. A thermal conductivity of less than 20 mW / m*K is particularly preferred.

[0059] The rigid PU foam according to the invention exhibits significantly lower thermal conductivity values ​​in both fresh and aged states compared to those produced without the addition of the perfluoropolyether used according to the invention, but also in the same manner; the thermal conductivity values ​​are typically at least 0.3 to 1.5 mW / m*K lower.

[0060] The present invention further provides the use of rigid PU foam according to the invention for reducing the energy consumption of refrigeration appliances, especially vertical and horizontal freezers, refrigerated display units and refrigerators.

[0061] The present invention further provides the use of the perfluoropolyether according to the invention as defined above in the specification for the following purposes:

[0062] (a) Production of rigid polyurethane foam, particularly using the composition according to the invention,

[0063] (b) Improve the thermal insulation properties of polyurethane foam, preferably rigid PU foam, especially in building applications or in the refrigeration field, and / or

[0064] (c) Reduce the thickness of rigid PU foam insulation while maintaining thermal insulation performance, especially in building applications or in the refrigeration field.

[0065] The perfluoropolyether used according to the present invention can be added directly to the reactive mixture used for the production of PU foam, or optionally premixed with other auxiliaries and additives in one of the components, preferably the blowing agent. This corresponds to a preferred embodiment of the present invention.

[0066] Against this backdrop, the present invention further provides a mixture suitable for producing rigid PU foam, comprising a perfluoropolyether according to the invention as defined above in the specification and at least one blowing agent selected from: hydrocarbons having 3, 4, or 5 carbon atoms, preferably cyclopentane, isopentane, and n-pentane; hydrofluorocarbons, preferably HFC 245fa, HFC 134a, and HFC 365mfc; hydrochlorofluorocarbons, preferably HCFC 141b; hydrofluoroolefins (HFO) or hydrohalogenated olefins, such as 1234ze, 1234yf, 1224yd, 1233zd(E), or 1336mzz; oxygen-containing compounds such as methyl formate, acetone, and dimethoxymethane; or chlorinated hydrocarbons, preferably dichloromethane and 1,2-dichloroethane.

[0067] In a preferred embodiment of the invention, the mixture is characterized in that the perfluoropolyether present therein, as a whole, comprises at least 25% by weight, preferably at least 50% by weight, more preferably at least 75% by weight, and particularly at least 90% by weight of the perfluoropolyether as defined above in the specification.

[0068] Another preferred embodiment of the invention is when the perfluoropolyether used as a whole is present in the mixture in a total amount of 0.1% to 50% by weight, preferably 0.5% to 30% by weight, particularly preferably 1.0% to 20% by weight.

[0069] The present invention further provides a method for producing rigid PU foam, wherein a mixture according to the present invention and as defined above is used.

[0070] The present invention further provides the use of the mixtures according to the invention as defined above in the production of rigid PU foam, and in particular for improving thermal insulation properties.

[0071] The production of rigid PU foam, as well as the components and formulations used therein, are known in themselves. The perfluoropolyether used according to the present invention can be used in conventional expandable formulations of rigid PU foam, particularly those formed from a compound (A) having reactive hydrogen atoms, a polyisocyanate component (B), and conventional auxiliaries and additives (C).

[0072] The polyols suitable as polyol components (A) for the purposes of this invention are all organic substances having one or more isocyanate reactive groups, preferably OH groups, and their formulations.

[0073] Preferred polyols are polyether polyols and / or polyester polyols and / or hydroxyl-containing aliphatic polycarbonates, especially polyether polycarbonate polyols, and / or naturally sourced polyols known as "natural oil-based polyols" (NOPs), which are commonly used in the production of polyurethane systems, such as preferred polyurethane coatings, polyurethane elastomers, and especially foams. The polyols typically have a functionality of 1.8 to 8 and a number-average molecular weight of preferably 500 to 15,000. Polyols with OH values ​​typically in the range of 10 to 1200 mg KOH / g are generally used.

[0074] The isocyanates suitable as isocyanate component (B) for the purposes of this invention are all isocyanates containing at least two isocyanate groups. Generally, all aliphatic, alicyclic, aryl aliphatic, and preferred aromatic polyfunctional isocyanates known per se can be used.

[0075] Specific examples include: alkylene diisocyanates having 4 to 12 carbon atoms in the alkylene moiety, such as dodecane 1,12-diisocyanate, 2-ethyltetramethylene 1,4-diisocyanate, 2-methylpentamethylene 1,5-diisocyanate, tetramethylene 1,4-diisocyanate, and preferably hexamethylene 1,6-diisocyanate (HMDI); alicyclic diisocyanates such as cyclohexane 1,3- and 1,4-diisocyanates and any mixtures of these isomers, 1-isocyanate-3,3,5-trimethyl-5-isocyanate-methylcyclohexane (isophorone diisocyanate or IPDI for short), hexahydrobenzyl 2,4- and 2,6-diisocyanates (hexahydrotolylene 2,4- and... 2,6-diisocyanate) and corresponding isomer mixtures; and preferred aromatic diisocyanates and polyisocyanates such as toluene 2,4- and 2,6-diisocyanate (TDI) and corresponding isomer mixtures, naphthalene diisocyanate, diethyltoluene diisocyanate, diphenylmethane 2,4'- and 2,2'-diisocyanate (MDI) mixed with polyphenyl polymethylene polyisocyanate (crude MDI) and mixtures of crude MDI with toluene diisocyanate (TDI). Organic diisocyanates and polyisocyanates can be used alone or in mixtures thereof. Corresponding "oligomers" of diisocyanates (IPDI trimers based on isocyanurates, biuret, and isocyanate dimers) can also be used. Furthermore, prepolymers based on the above isocyanates can be used.

[0076] The terms "isocyanate component" and "polyisocyanate" are used synonymously in the context of this invention.

[0077] Isocyanates modified by introducing urethane, isocyanate dimers, isocyanurates, urethane and other groups can also be used; these are called modified isocyanates.

[0078] Therefore, particularly preferred and especially suitable organic polyisocyanates are various isomers of toluene diisocyanate (toluene 2,4- and 2,6-diisocyanates (TDI) in pure form or in mixtures of isomers of various compositions), diphenylmethane 4,4'-diisocyanate (MDI), "crude MDI" or "polymeric MDI" (containing the 4,4' isomer of MDI as well as the 2,4' and 2,2' isomers and products having more than two rings), and bicyclic products referred to as "pure MDI" and consisting mainly of mixtures of 2,4' and 4,4' isomers, and prepolymers derived therefrom. Examples of particularly suitable isocyanates are detailed, for example, in EP1712578, EP 1161474, WO 00 / 58383, US 2007 / 0072951, EP 1678232 and WO 2005 / 085310, which are incorporated herein by reference in their entirety.

[0079] The preferred ratio of isocyanate to polyol (expressed as an index of the formulation, i.e., the stoichiometric ratio of isocyanate groups to isocyanate reactive groups (e.g., OH groups, NH groups) multiplied by 100) is in the range of 10 to 1000, preferably in the range of 80 to 500. An index of 100 indicates that the molar ratio of reactive groups is 1:1.

[0080] The additives and auxiliaries (C) used can be compounds commonly used in the formulation of PU foam, especially rigid PU foam, including catalysts, foam stabilizers, blowing agents, flame retardants, fillers, colorants and light stabilizers.

[0081] Suitable catalysts for the purposes of this invention are substances that catalyze gelation reactions (isocyanate-polyol), foaming reactions (isocyanate-water), or dimerization or trimerization of isocyanates. Conventional catalysts known from the prior art can be used, including, for example, amines (cyclic, acyclic; monoamines, diamines, oligomers having one or more amino groups), ammonium compounds, organometallic compounds, and metal salts, preferably those of tin, iron, bismuth, potassium, and zinc. In particular, mixtures of multiple components can be used as catalysts. Suitable amounts used depend on the type of catalyst, and particularly for potassium salts, in the range of 0.05 to 5 parts by weight, or 0.1 to 10 parts by weight (based on 100 parts by weight of polyol).

[0082] Suitable foam stabilizers are surfactants, such as organic surfactants or preferably polyether-modified siloxanes (PES). In the context of this invention, any of those that promote foam formation (stabilization, cell conditioning, cell opening, etc.) may be used. These compounds are well known in the art. The typical amount of the polyether siloxane foam stabilizer used is preferably 0.5 to 5 parts by weight per 100 parts by weight of polyol, more preferably 1 to 3 parts by weight per 100 parts by weight of polyol.

[0083] For example, the following patent specifications describe corresponding PES that can be used in the context of this invention: CN103665385, CN 103657518, CN 103055759, CN 103044687, US 2008 / 0125503, US 2015 / 0057384, EP 1520870 A1, EP 1211279, EP 0867464, EP 0867465, EP 0275563.

[0084] Water is preferably added to foamable formulations as a chemical blowing agent because it reacts with isocyanates to release carbon dioxide gas. The suitable water content for the purposes of this invention depends on whether a physical blowing agent is used in addition to water. In the case of foams foamed from pure water, this value is preferably in the range of 1 to 20 parts by weight per 100 parts by weight of polyol, but when other blowing agents are used, the amount used is preferably reduced to 0.1 to 5 parts by weight per 100 parts by weight of polyol.

[0085] The physical blowing agent used can be a corresponding compound with a suitable boiling point. Similarly, chemical blowing agents that react with NCO groups to release gas can also be used, such as water or formic acid, as already mentioned. Examples of blowing agents are liquefied CO2; nitrogen; air; volatile liquids, such as hydrocarbons having 3, 4, or 5 carbon atoms, preferably cyclopentane, isopentane, and n-pentane; hydrofluorocarbons, preferably HFC 245fa, HFC 134a, and HFC 365mfc; hydrochlorofluorocarbons, preferably HCFC 141b; hydrofluoroolefins (HFO) or hydrohalogenated olefins, such as 1234ze, 1234yf, 1224yd, 1233zd(E), or 1336mzz; oxygen-containing compounds such as methyl formate, acetone, and dimethoxymethane; or chlorinated hydrocarbons, preferably dichloromethane and 1,2-dichloroethane.

[0086] As additives, all substances known from existing technologies and used in the production of polyurethane, especially polyurethane foam, can be used, such as crosslinking agents and chain extenders, stabilizers that resist oxidative degradation (called antioxidants), flame retardants, surfactants, biocides, cell openers, solid fillers, antistatic additives, thickeners, dyes, pigments, color pastes, fragrances, emulsifiers, etc.

[0087] Insulating foams used for building thermal insulation meet fire safety requirements. Flame retardants suitable for this purpose are preferably liquid organophosphorus compounds, such as halogen-free organophosphates, like triethyl phosphate (TEP), halophosphates, such as tris(1-chloro-2-propyl) phosphate (TCPP) and tris(2-chloroethyl) phosphate (TCEP), and organophosphonates, such as dimethyl methylphosphonate (DMMP) and dimethyl propylphosphonate (DMPP); or solids, such as ammonium polyphosphate (APP) and red phosphorus. Suitable flame retardants further include halogenated compounds, such as halogenated polyols, and solids such as expandable graphite and melamine.

[0088] The present invention further provides the use of polyurethane foam according to the invention as an insulation board and insulation material, and a cooling device including polyurethane foam according to the invention as an insulation material.

[0089] The present invention further provides the use of the perfluoropolyether according to the invention, as characterized above in the specification, for reducing the thickness of rigid PU foam insulation layers while maintaining thermal insulation properties, particularly in insulation boards and insulation materials.

[0090] In the context of this invention, preferred PU foam formulations contain the perfluoropolyether according to the invention and result in 10 to 900 kg / m³. 3 The foam density and, according to a preferred embodiment of the invention, the following composition:

[0091]

[0092] The formulations according to the invention can be processed by any method familiar to those skilled in the art to obtain the desired PU foam.

[0093] Rigid polyurethane foam or rigid PU foam are established technical terms. The known and fundamental difference between flexible and rigid foams is that flexible foams exhibit elastic properties, and therefore deformation is reversible. Conversely, rigid foams undergo permanent deformation. In the context of this invention, rigid polyurethane foam should be understood in particular as foam according to DIN 7726, having a compressive strength advantageously ≥20 kPa, preferably ≥80 kPa, more preferably ≥100 kPa, more preferably ≥150 kPa, and particularly preferably ≥180 kPa according to DIN 53 421 / DIN EN ISO 604:2003-12. Furthermore, according to DIN EN ISO 4590:2016-12, this rigid polyurethane foam advantageously has a closed-cell content greater than 50%, preferably greater than 80%, and particularly preferably greater than 90%.

[0094] The rigid PU foam according to the present invention can be used as or used in the production of insulation materials, preferably insulation panels, refrigerators, insulating foams, roof liner, packaging foams or spray foams.

[0095] The PU foam according to the invention can be advantageously used, particularly, in the cold storage, refrigeration, and household appliance industries, for example, for the production of insulation panels for roofs and walls, as insulation material in containers and warehouses for frozen foods, and for refrigeration and freezing appliances.

[0096] Further preferred applications are in vehicle structures, particularly for the production of vehicle headliners, body parts, interior trim, cooling systems, large containers, transport pallets, and packaging laminates; in the furniture industry, for example, for furniture parts, doors, and linings; and in electronic applications.

[0097] The present invention further provides the use of rigid PU foam as an insulation material in refrigeration technology, refrigeration equipment, construction industry, automotive industry, shipbuilding industry and / or electronics industry; as an insulation board; as a spray foam; or as a single-component foam.

[0098] The following embodiments describe the invention by way of example, and are not intended to limit the invention to the embodiments referred to in the embodiments. The scope of the invention will be apparent from the entire contents of the specification and claims. Example

[0099] Example 1: Rigid PU foam

[0100] The following foam formulations are used for performance comparison:

[0101]

[0102] * Polyether polyols based on sucrose, sorbitol, o-TDA, and glycerol

[0103] **Catalysts from Evonik Industries AG

[0104] ***From Evonik Industries AG B 84813

[0105] ****Perfluoropolyethers having structures (i), (ii) and (iii)

[0106] *****Polymerized MDI, 200 mPa*s, 31.5% NCO, functionality 2.7.

[0107] Comparative foaming was performed by manual mixing. For this purpose, polyol, catalyst, water, foam stabilizer, perfluoropolyether, and blowing agent were weighed into a beaker and mixed for 30 seconds at 1000 rpm using a disc stirrer (6 cm in diameter). The amount of blowing agent evaporated during the mixing operation was determined by reweighing and replenishing. MDI was then added, and the reaction mixture was stirred for 7 seconds at 3000 rpm using the same stirrer and immediately transferred to an aluminum mold measuring 145 cm x 14 cm x 3.5 cm, heated to 45°C and tilted at a 10° angle (along the 145 cm long side) and lined with a polyethylene film. In this case, the foam formulation was introduced into the lower side, causing the expanded foam to fill the mold in the feed area and rise towards the higher side. The amount of foam formulation used was calculated such that it was 10% higher than the minimum filling amount required for the mold.

[0108] Ten minutes later, the foam was demolded. After one day of foaming, the foam was analyzed. Surface and internal defects were subjectively assessed on a scale of 1 to 10, where 10 represents (idealized) flawless foam and 1 represents foam with very obvious defects. Thermal conductivity (λ value in mW / m·K) was measured on a 2.5 cm thick disk using a Hesto LambdaControl type device (model HLC X206) at an average temperature of 10°C, according to standard EN12667:2001.

[0109] The results are summarized in the table below:

[0110]

[0111] The results show that the use of the perfluoropolyether according to the present invention can achieve a significant improvement in thermal conductivity, with values ​​in both fresh and aged states being significantly lower than the reference values ​​for foam without the addition of perfluoropolyether.

[0112] It should be particularly emphasized here that even the addition of very small amounts of the perfluoropolyether according to the invention results in measurable improvement.

[0113] All other application-related foam properties are only negligibly affected (if any) by the perfluoropolyether according to the invention. No changes were found, or only negligible degradation, even in cases where the surface quality of the foam test samples is quite sensitive.

[0114] Example 2: Rigid PIR foam

[0115] The following foam formulations are used for performance comparison:

[0116] Components weight ratio Polyester polyols* 100 Amine catalysts** 0.4 Potassium trimer catalyst*** 5 Polyether siloxane **** 2 water 0.8 Cyclopentane / isopentane 70:30 19 Flame retardant TCPP 10 According to the present invention, perfluoropolyether***** 0-4 MDI****** 220

[0117] *From Stepan PS 2412

[0118] **From Evonik Industries AG 5

[0119] ***From Evonik Industries AG 70LO

[0120] ****From Evonik Industries AG B 84504

[0121] ***** Perfluoropolyethers having structures (i), (ii) and (iii)

[0122] ******Polymerized MDI, 200 mPa*s, 31.5% NCO, functionality 2.7.

[0123] Comparative foaming was performed by manual mixing. For this purpose, the polyol, catalyst, water, foam stabilizer, flame retardant, perfluoropolyether, and blowing agent were weighed into a beaker and mixed for 30 seconds at 1000 rpm using a disc stirrer (6 cm in diameter). The amount of blowing agent that had evaporated during the mixing operation was determined by reweighing and replenishing. MDI was then added, and the reaction mixture was stirred for 5 seconds at 3000 rpm using the same stirrer and immediately transferred to an open mold with dimensions of 27.5 x 14 x 14 cm (W x H x D).

[0124] Ten minutes later, the foam was demolded. One day after foaming, the foam was analyzed. Surface and internal defects were subjectively assessed on a scale of 1 to 10, where 10 represents (idealized) flawless foam and 1 represents foam with very obvious defects. Thermal conductivity (λ value in mW / m·K) was measured on a 2.5 cm thick disk using a Hesto LambdaControl type device (model HLC X206) at an average temperature of 10°C, according to standard EN12667:2001. To determine the aging value of thermal conductivity, the test samples were stored at 70°C for more than 7 days and then measured again.

[0125] The results are summarized in the table below:

[0126]

[0127] The results again demonstrate that the use of the perfluoropolyether according to the present invention can achieve a significant improvement in thermal conductivity, with values ​​in both fresh and aged states being significantly lower than the reference values ​​for foams without the addition of perfluoropolyether.

[0128] It should be particularly emphasized here that even the addition of very small amounts of the perfluoropolyether according to the invention results in measurable improvement.

[0129] All other application-related foam properties are only negligibly affected (if any) by the perfluoropolyether according to the invention. No changes were found, or only negligible degradation, even in cases where the surface quality of the foam test samples is quite sensitive.

[0130] Example 3: Rigid PIR foam

[0131] The following foam formulations are used for performance comparison:

[0132] Components weight ratio Polyester polyols* 100 Amine catalysts** 0.4 Potassium trimer catalyst*** 5 Polyether siloxane **** 2 water 0.8 Cyclopentane / isopentane 70:30 19 Flame retardant TCPP 10 According to the present invention, perfluoropolyether***** 0.1-4 MDI****** 220

[0133] *From Stepan PS 2412

[0134] **From Evonik Industries AG 5

[0135] ***From Evonik Industries AG 70LO

[0136] ****From Evonik Industries AG B 84504

[0137] ***** Perfluoropolyethers having structures (i), (ii) and (iii)

[0138] ******Polymerized MDI, 200 mPa*s, 31.5% NCO, functionality 2.7.

[0139] Comparative foaming was performed by manual mixing. For this purpose, the polyol, catalyst, water, foam stabilizer, flame retardant, perfluoropolyether, and blowing agent were weighed into a beaker and mixed for 30 seconds at 1000 rpm using a disc stirrer (6 cm in diameter). The amount of blowing agent that had evaporated during the mixing operation was determined by reweighing and replenishing. MDI was then added, and the reaction mixture was stirred for 5 seconds at 3000 rpm using the same stirrer and immediately transferred to an aluminum mold with dimensions of 25 cm x 50 cm x 7 cm, lined with a polyethylene film and kept at a constant temperature of 60°C.

[0140] Ten minutes later, the foam was demolded. One day after foaming, the foam was analyzed. Surface and internal defects were subjectively assessed on a scale of 1 to 10, where 10 represents (idealized) flawless foam and 1 represents foam with very obvious defects. Thermal conductivity (λ value in mW / m·K) was measured on a 2.5 cm thick disk using a Hesto LambdaControl type device (model HLC X206) at an average temperature of 10°C, according to standard EN12667:2001. To determine the aging value of thermal conductivity, the test samples were stored at 70°C for more than 7 days and then measured again.

[0141] The results are summarized in the table below:

[0142]

[0143] The results again demonstrate that the use of the perfluoropolyether according to the present invention can achieve a significant improvement in thermal conductivity, with values ​​in both fresh and aged states being significantly lower than the reference values ​​for foams without the addition of perfluoropolyether.

[0144] It should be particularly emphasized here that even the addition of very small amounts of the perfluoropolyether according to the invention results in measurable improvement.

[0145] All other application-related foam properties are only negligibly affected (if any) by the perfluoropolyether according to the invention. No changes were found, or only negligible degradation, even in cases where the surface quality of the foam test samples is quite sensitive.

Claims

1. A composition for producing rigid polyurethane foam, said composition comprising at least one isocyanate component, a polyol component, a blowing agent selected from hydrocarbons, hydrohalogenated olefins, and mixtures thereof having 3, 4, or 5 carbon atoms, optionally a catalyst for catalyzing the formation of urethane or isocyanurate bonds, and optionally a foam stabilizer, characterized in that, The composition further comprises at least three perfluoropolyethers selected from (i) to (vii) of the following structures: (Structure i) 1,1,1,2,3,3-hexafluoro-2,3-bis(pentafluoroethoxy)propane (Structure ii) 1,1,1,2,3,3-Hexafluoro-3-(pentafluoroethoxy)-2-(trifluoromethoxy)propane (Structure iii) 1,1,1,2,3,3-Hexafluoro-2-(pentafluoroethoxy)-3-(trifluoromethoxy)propane (Structure vi) 1,1,1,2,3,3-Hexafluoro-3-{[1,1,1,2,3,3-Hexafluoro-3-(trifluoromethoxy)propane-2-yl]oxy}-2-(trifluoromethoxy)propane (Structure vii) 1,1,1,3,3,4,6,6,7,9,9,10,12,12,12-pentadecanofluoro-4,7,10-tris(trifluoromethyl)-2,5,8,11-tetraoxadodecane 。 2. The composition according to claim 1, characterized in that, The hydrogen halide olefins therein are 1234ze, 1234yf, 1224yd, 1233zd(E) or 1336mzz.

3. The composition according to claim 1, characterized in that, The selected perfluoropolyethers include structures (i), (ii) and (vii).

4. The composition according to claim 1, characterized in that, The composition further contains a perfluoropolyether with a cyclic structure of formula (b): (Formula b) Where a = 1 to 4, and R2, R3 and R4 are independently -F or -CF3, or one of the groups R2, R3 and R4 is -CF3 and the other two groups are -F.

5. The composition according to claim 4, characterized in that, Where a = 1 to 2.

6. The composition according to claim 4, characterized in that, Where a = 1.

7. The composition according to claim 4, characterized in that, All groups R2, R3, and R4 are -F.

8. The composition according to claim 1, characterized in that, The composition comprises four perfluoropolyethers selected from structures (i), (ii), (iii), (vi), and (vii).

9. The composition according to claim 1, characterized in that, The composition comprises all of the perfluoropolyethers of structures (i), (ii), (iii), (vi), and (vii).

10. The composition according to claim 4, characterized in that, As a perfluoropolyether with a cyclic structure of formula (b), at least 2,2,3,5,5,6-hexafluoro-3,6-bis(trifluoromethyl)-1,4-dioxane is present. (Structure viii).

11. The composition according to any one of claims 1 to 10, characterized in that, Both perfluoropolyethers having structures (i), (ii), (iii), (vi) and (vii) as described in claim 1 and perfluoropolyethers with cyclic structures of formula (b) as described in claim 4 are present.

12. The composition according to claim 11, characterized in that, The perfluoropolyethers having structures (i), (ii), (iii), (vi) and (vii) as described in claim 1 and the perfluoropolyether having structure (viii) as described in claim 10 are both present.

13. The composition according to any one of claims 1 to 10, characterized in that, The perfluoropolyether present as a whole comprises at least 25% by weight of the perfluoropolyethers as defined in any one of claims 1 to 10.

14. The composition according to claim 13, characterized in that, The perfluoropolyether present as a whole comprises at least 50% by weight of the perfluoropolyethers as defined in any one of claims 1 to 10.

15. The composition according to claim 13, characterized in that, The perfluoropolyether present as a whole comprises at least 75% by weight of the perfluoropolyethers as defined in any one of claims 1 to 10.

16. The composition according to claim 13, characterized in that, The perfluoropolyether present as a whole comprises at least 90% by weight of the perfluoropolyethers as defined in any one of claims 1 to 10.

17. The composition according to any one of claims 1 to 10, characterized in that, Based on 100 parts of polyol, the total amount of the perfluoropolyether used as a whole is 0.01 to 15 parts.

18. The composition according to claim 17, characterized in that, Based on 100 parts of polyol, the total amount of the perfluoropolyether used as a whole is 0.1 to 10 parts.

19. The composition according to claim 17, characterized in that, Based on 100 parts of polyol, the total amount of the perfluoropolyether used as a whole is 0.1 to 5 parts.

20. A method for producing PU foam based on a foamable reaction mixture, said foamable reaction mixture containing polyisocyanate, a compound having reactive hydrogen atoms, a blowing agent selected from hydrocarbons having 3, 4, or 5 carbon atoms, hydrohalogenated olefins, and mixtures thereof, a foam stabilizer, and other additives that may be present, characterized in that... Additionally, perfluoropolyethers are used, which are selected from at least three structures of (i) to (vii) as defined in any one of claims 1 to 10, and optionally the structure of formula (b).

21. A method for producing PU foam based on a foamable reaction mixture, said foamable reaction mixture containing polyisocyanate, a compound having reactive hydrogen atoms, a blowing agent selected from hydrocarbons having 3, 4, or 5 carbon atoms, hydrohalogenated olefins, and mixtures thereof, a foam stabilizer, and other additives that may be present, characterized in that... Additionally, perfluoropolyethers are used that employ at least three structures selected from (i) to (vii) as defined in any one of claims 1 to 10, as well as the optionally present structure (viii).

22. The method according to claim 20 or 21, characterized in that, The PU foam is rigid PU foam.

23. The method according to claim 20 or 21, characterized in that, The hydrogen halide is 1234ze, 1234yf, 1224yd, 1233zd(E) or 1336mzz.

24. PU foam produced by the method according to claim 20 or 21.

25. The PU foam according to claim 24, wherein it is a rigid PU foam.

26. Use of the PU foam according to claim 24 or 25 for reducing energy consumption of refrigeration appliances.

27. The use according to claim 26, wherein the refrigeration appliance is a vertical freezer, a horizontal freezer, or a refrigerated display unit.

28. The use according to claim 26, wherein the refrigeration appliance is a refrigerator.

29. The perfluoropolyether of at least three structures selected from (i) to (vii) and optionally the structure of formula (b) in the composition according to any one of claims 1 to 10 is used for the following purposes. (a) Production of rigid polyurethane foam, or (b) Improve the thermal insulation properties of polyurethane foam.

30. The perfluoropolyether of the composition according to any one of claims 1 to 10, comprising at least three structures selected from (i) to (vii) and optionally present structure (viii), is used for the following purposes. (a) Production of rigid polyurethane foam, or (b) Improve the thermal insulation properties of polyurethane foam.

31. The use according to claim 29 or 30, wherein it is used to reduce the thickness of a rigid PU foam insulation layer while maintaining thermal insulation properties.

32. The use according to claim 29 or 30, wherein the composition according to any one of claims 1 to 10 is used to produce rigid polyurethane foam.

33. The use according to claim 29 or 30, wherein the polyurethane foam is rigid PU foam.

34. The use according to claim 29 or 30, wherein the improvement of the thermal insulation properties of the polyurethane foam is in building applications or in the field of refrigeration.

35. The use according to claim 31, wherein reducing the thickness of the rigid PU foam insulation layer while maintaining thermal insulation properties is in building applications or in the field of refrigeration.

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