Open-cell flexible polyurethane foam with improved self-extinguishing fire test performance

Abstract

The present invention provides self-extinguishing flexible polyurethane foams, reaction mixtures, and methods for preparing them, wherein the foam-forming reaction mixture comprises an isocyanate component and a separate polyol component. The isocyanate component is one or more aromatic polyisocyanates containing two or more aromatic or phenyl groups and an aromatic phosphorus-containing flame retardant. The polyol component is a mixture of one or more first polyols, one or more high molecular weight polyols, a brominated polyether flame retardant, one or more catalysts, and one or more blowing agents. The brominated polyether flame retardant is 7.5 wt% to 17.5 wt% based on the weight of the polyol component, has a bromine content of 30 wt% to 40 wt%, and an average hydroxyl functionality of 2.3 to 3.5. The flexible polyurethane foam has a total density of 200 g / L to 280 g / L.

Description

[0001] The present invention relates to reaction mixtures for the preparation of open-cell flexible polyurethane foams, the open-cell foams obtained therefrom, and methods for their preparation. More specifically, the present invention relates to reaction mixtures for the formation of fire-resistant flexible polyurethane foams and methods for their preparation, which reaction mixtures contain a liquid flame retardant composition, are substantially free of solid flame retardants, and exhibit good self-extinguishing properties and physical characteristics, wherein the reaction mixture for the preparation of flexible polyurethane foams comprises a polyol component and a polyisocyanate component, the polyol component contains a hydroxyl-functional brominated polyol having an average hydroxyl functionality of 2.3 to 3.5, and the polyisocyanate component contains a triphenyl phosphate compound. Background Art

[0002] Known flexible polyurethane foams are flammable and typically melt and drip when exposed to a flame, resulting in the spread of burning droplets. In addition, flexible polyurethane foams may smolder after the flame has been extinguished. Recently, several automobile manufacturers have issued more stringent self-extinguishing fire tests for flexible polyurethane foams used for engine encapsulation, such as the Volkswagen PV 3357 fire test. The new self-extinguishing fire test determines the combustion behavior due to surface and edge flame exposure and measures the response of the foam to the flame after the ignition source has been removed. After the flame is removed, the flexible polyurethane foam must not continue to burn, which means it must be self-extinguishing; and any dripping flexible polyurethane foam must also not continue to burn.

[0003] Among known flexible polyurethane foams, the only flexible polyurethane foams that pass the self-extinguishing fire test contain solid flame retardants such as expandable graphite. However, such solid flame retardants cannot be processed without using additional processing equipment. For example, expandable graphite has an acid in its chemical structure, so it can reduce the reactivity of the polyol component with the isocyanate. To solve this acidification problem, manufacturers of flexible polyurethane foams use a special mixing head and a high-pressure pump equipped with a filter for oversized solids. However, many producers of flexible polyurethane foams for automotive use have a single foam production line to produce components for different original equipment manufacturers (OEMs).

[0004] In addition, the flexible polyurethane foam used in engine compartment enclosures must comply with the acoustic specifications for sound absorption performance to reduce noise from the engine. The use of solid flame retardant compositions can have a negative impact on the acoustic properties of the foam. Accordingly, there remains a need for a flexible polyurethane foam for engine encapsulation that is free of solid flame retardants and that meets both self-extinguishing and acoustic specifications and physical property requirements including compression stress resistance (DIN EN ISO 3386-1), tensile strength (DIN EN ISO 1798), and 50% compression set (DIN EN ISO 1856) both initially and after exposure to heat and / or humidity.

[0005] Recently, World Intellectual Property Organization (WIPO) Publication WO2019204625A1, issued to FRX Polymers Inc., discloses flexible polyurethane foams containing halogen-free flame retardant compositions that achieve some of the physical properties required for automotive engine compartment enclosures. However, the FRX polymers flexible polyurethane foams do not achieve an acceptable self-extinguishing fire resistance, for example, for use in the engine compartment of a vehicle.

[0006] The present inventors have strived to provide flexible polyurethane foam-forming reaction mixtures that contain liquid flame retardants and that are capable of providing flexible polyurethane foams that meet all current self-extinguishing and physical property specifications of major automobile manufacturers. SUMMARY OF THE INVENTION

[0007] According to the present invention, the flexible polyurethane foam forming reaction mixture comprises an isocyanate component which is one or more aromatic polyisocyanates or their prepolymers containing two or more aromatic or phenyl groups and 12% to 27% by weight or preferably 14% to 25% by weight of an aromatic phosphorus-containing flame retardant based on the weight of the isocyanate component, preferably a triaryl phosphorus-containing flame retardant containing three phenyl or aromatic groups; and further comprises a polyol component which is a mixture of one or more (preferably two or more) first polyols and one or more high molecular weight polyols, a flame retardant, one or more catalysts and one or more blowing agents (preferably water). The first polyol has an average of 2.4 to 3.5 hydroxyl groups and a hydroxyl value of 26 mg KOH / g to 44 mg KOH / g according to ASTM D4274, for example 30 mg KOH / g to 40 mg KOH / g or 32 mg KOH / g to 37 mg KOH / g, such as a propoxylated polyol initiated with an ethylene oxide (EO) capped triol (e.g., glycerol). The high molecular weight polyol has an average of 1.8 to 6 or preferably 3 to 5.2 hydroxyl groups and a hydroxyl value of 27 mg KOH / g to 38 mg KOH / g according to ASTM D4274, for example 31 mg KOH / g to 34 mg KOH / g, such as a propoxylated polyether polyol initiated with an EO capped triol and a sugar alcohol. The flame retardant is a halogenated polyether polyol flame retardant in an amount of 7.5% to 17.5% by weight or preferably 9% to 16.5% by weight based on the weight of the polyol component, preferably a brominated polyether flame retardant with a bromine content of 30% to 40% and an average hydroxyl functionality of 2.3 to 3.5. Based on the total weight of the polyol component of the reaction mixture, the total amount of the one or more blowing agents can range from 1.0% to 2.0% by weight, or preferably 1.1% to 1.3% by weight. The relative amounts of the isocyanate component and the polyol component in the reaction mixture can be sufficient to provide an isocyanate index of 0.86 to 1.15, or preferably 0.89 to 1.12, or more preferably 0.89 to 1.11.

[0008] A foam-forming reaction mixture according to the present invention, wherein the isocyanate component may comprise diphenylmethane diisocyanate (MDI) in the form of its 2,4'-isomer, 2,2'-isomer or 4,4'-isomer (monomeric MDI); polymeric MDI, which is the uretonimine, urethane, biuret or isocyanurate of MDI; MDI prepolymers, such as prepolymers made from a glycol chain extender and one or more of MDI and polymeric MDI or mixtures thereof, preferably a mixture of a prepolymer made from 40% to 60% by weight of monomeric MDI based on the weight of the isocyanate component and 40% to 60% by weight of polymeric MDI based on the weight of the isocyanate component and a glycol.

[0009] A foam-forming reaction mixture according to the present invention, wherein the polyol component may comprise 55% to 70% by weight or preferably 58% to 67.5% by weight of said one or more (preferably two or more) first polyols based on the weight of the polyol component, and 13% to 30% by weight or preferably 14% to 27% by weight of said one or more high molecular weight polyols based on the weight of the polyol component.

[0010] A foam-forming reaction mixture according to the present invention, wherein the catalyst in the polyol component comprises an amine catalyst, such as, for example, a reactive amine catalyst, in an amount of 0.1% to 1% by weight based on the total weight of the polyol component. Examples of amine catalysts are tertiary amines, such as bis(N,N-dimethylaminoethyl) ether. As used herein, "reactive amine catalyst" means a catalyst containing at least one tertiary amino group and at least one isocyanate-reactive group (such as a hydroxyl group, a primary amino group or a secondary amino group) and that reacts with the polymer structure when the reaction mixture cures. A cell regulator can also be used as a catalyst.

[0011] A foam-forming reaction mixture according to the present invention, wherein the polyol component may further comprise any amine gelling catalyst, for example, a non-volatile catalyst such as diazabicyclooctane. Such amine gelling catalysts may be present in an amount of 0.1% to 1% by weight based on the total weight of the polyol component.

[0012] A foam-forming reaction mixture according to the present invention, wherein the polyol component further comprises a cell regulator, such as iminodiethanol (DEOA). Such cell regulators may account for 0.3% to 0.7% by weight based on the total weight of the polyol component.

[0013] A foam-forming reaction mixture according to the present invention, wherein the polyol component further comprises one or more additives selected from secondary blowing agents or colorants.

[0014] A foam-forming reaction mixture according to the present invention, wherein the isocyanate component further comprises one or more additives selected from chain extenders or colorants.

[0015] In another aspect of the present invention, a flexible polyurethane foam in the form of a foaming polyurethane comprises an open-cell foam which may have a total density (DIN EN ISO 845) of, for example, 200 g / L to 280 g / L or preferably 200 g / L to 260 g / L, and may comprise an aromatic polyurethane containing two or more aromatic or phenyl groups and an aromatic phosphorus-containing flame retardant in an amount of 6% to 14% by weight or preferably 7% to 13% by weight based on the weight of the foaming polyurethane, preferably a triaryl phosphorus-containing flame retardant containing three phenyl or aromatic groups; and may further comprise a polyol in the form of a polyurethane which is a mixture of one or more (preferably two or more) first polyols, one or more high molecular weight polyols, and a flame retardant, the first polyol having an average of 2.4 to 3.5 hydroxyl groups and a hydroxyl value of 26 mg KOH / g to 44 mg KOH / g according to ASTM D4274 or, for example, 30 mg KOH / g to 40 mg KOH / g or 32 mg KOH / g to 37 mg KOH / g, such as a propoxylated polyol initiated with an ethylene oxide (EO)-capped triol (e.g., glycerol), the high molecular weight polyol having an average of 1.8 to 6 or preferably 3 to 5.2 hydroxyl groups and a hydroxyl value of 27 mg KOH / g to 38 mg KOH / g according to ASTM D4274 or, for example, 31 mg KOH / g to 34 mg KOH / g, such as a propoxylated polyether polyol initiated with an EO-capped triol and a sugar alcohol, the flame retardant being a halogenated polyether polyol flame retardant in an amount of 3.7% to 9% by weight or preferably 4.5% to 8.5% by weight based on the weight of the foaming polyurethane, preferably a brominated polyether flame retardant having a bromine content of 30% to 40% and an average hydroxyl functionality of 2.3 to 3.5 in the form of a urethane.

[0016] The flexible polyurethane foam according to the present invention can be formed from any of the reaction mixtures in the preferred reaction mixtures of the present invention, particularly wherein the aromatic phosphorus-containing flame retardant is a triaryl phosphorus-containing flame retardant containing three phenyl or aromatic groups, or more preferably a triaryl phosphorus-containing flame retardant containing C1 to C4 alkyl groups, for example, isopropyl triphenyl phosphate.

[0017] In another aspect, according to the present invention, a method for preparing a flexible polyurethane foam may include mixing an isocyanate component with a polyol component to form a reaction mixture and foaming the reaction mixture, wherein the isocyanate component includes: one or more aromatic polyisocyanates containing two or more aromatic or phenyl groups and 12 wt% to 27 wt% or preferably 14 wt% to 25 wt% of an aromatic phosphorus-containing flame retardant based on the weight of the isocyanate component, preferably a triaryl phosphorus-containing flame retardant containing three or more phenyl or aromatic groups; additionally, wherein the polyol component includes: a mixture of one or more (preferably two or more) first polyols with one or more high molecular weight polyols, a flame retardant, one or more catalysts, and one or more blowing agents (preferably water), the first polyol having an average of 2.4 to 3.5 hydroxyl groups and a hydroxyl value of 26 mg KOH / g to 44 mg KOH / g according to ASTM D4274 or for example 30 mg KOH / g to 40 mg KOH / g or 32 mg KOH / g to 37 mg KOH / g, such as an ethoxylated triol (e.g., glycerol)-initiated propoxylated polyol, the high molecular weight polyol having an average of 1.8 to 6 or preferably 3 to 5.2 hydroxyl groups and a hydroxyl value of 27 mg KOH / g to 38 mg KOH / g according to ASTM D4274 or for example 31 mg KOH / g to 34 mg KOH / g, such as an ethoxylated triol and a sugar alcohol-initiated propoxylated polyether polyol, the flame retardant being a halogenated polyether polyol flame retardant in an amount of 7.5 wt% to 17.5 wt% or preferably 9 wt% to 16.5 wt%, preferably a brominated polyether flame retardant having a bromine content of 30 wt% to 40 wt% and an average hydroxyl functionality of 2.3 to 3.5. Based on the total weight of the polyol component of the reaction mixture, the total amount of the one or more blowing agents may range from 1.0 wt% to 1.3 wt%, or preferably 1.1 wt% to 1.3 wt%. The foam reaction may be carried out in a mold or outside a mold. The relative amounts of the isocyanate component and the polyol component in the reaction mixture may be sufficient to provide an isocyanate index of 0.86 to 1.15 or preferably 0.89 to 1.13 or more preferably 0.91 to 1.12. Detailed Description

[0018] According to the present invention, an open-cell non-skinning flexible polyurethane foam can be produced for engine encapsulation components and will not drip or burn in the presence of an ignition source. The density of the flexible polyurethane foam ranges from 200 kg / m 3 to 280 kg / m 3And can be made from a reaction mixture containing only a liquid flame retardant, such that it has excellent physical properties. Flexible polyurethane foams can be formed from a reaction mixture containing an aromatic polyisocyanate and a high molecular weight polyol having at least 3 hydroxyl groups. Further, in the reaction mixture, the combination of a halogenated polyether polyol flame retardant on the polyol side and a triaryl phosphorus-containing flame retardant added on the isocyanate side enables the flexible polyurethane foams of the present invention to meet stringent fire tests and physical properties without adding solid flame retardants such as expandable graphite.

[0019] The present invention provides flexible polyurethane foams that produce a char upon burning that prevents the foam from dripping. The presence of phosphorus helps to extinguish the flame. Further, the flexible polyurethane foams according to the present invention pass the common and influential United States Department of Transportation (DOT) Federal Motor Vehicle Safety Standard (FMVSS) 302 - Flammability of Interior Materials in Passenger Cars, Multipurpose Passenger Vehicles, Trucks, and Buses or MVSS 302. Further, the flexible polyurethane foams of the present invention meet one or more or all of the compression stress resistance, tensile strength, and 50% compression set tests of at least one major automotive manufacturer both initially and after exposure to heat and / or humidity.

[0020] All recited ranges are inclusive and combinable. For example, the disclosed proportions of monomers containing ethylenically unsaturated acid functional groups in copolymerized form that contain 1.8 wt% or more, such as up to 5 wt%, or 2 wt% to 4 wt% based on the total weight of the monomers used to prepare the copolymer will include proportions of 1.8 wt% to 5 wt%, or 1.8 wt% to 2 wt%, or 1.8 wt% to 4 wt%, or 2 wt% to 4 wt%, or 2 wt% to 5 wt%, or 4 wt% to 5 wt%.

[0021] Unless otherwise specified, all temperature and pressure units are at room temperature and standard pressure, and all humidity conditions are at 30% relative humidity.

[0022] Unless otherwise specified, any term containing parentheses alternatively refers to the entire term as if the parentheses were present and the term without the parentheses, and combinations of each alternative. Thus, as used herein, the term "(meth)acrylate" and like terms are intended to include acrylates, methacrylates, and mixtures thereof.

[0023] As used herein, the term "ASTM" refers to publications of ASTM International, Conshohocken, Pa.

[0024] As used herein, the term "component" refers to a composition containing one or more ingredients that are combined with another component to initiate a reaction, polymerization, foam formation, or curing. The components are stored separately until combined at the time of use or reaction.

[0025] As used herein, the term "DIN" refers to publications of the German Institute for Standardization (Deutsches Institut für Normung), Berlin, Germany.

[0026] As used herein, the term "ISO" refers to publications of the International Organization for Standardization, Geneva, Switzerland.

[0027] As used herein, unless otherwise specified, the term "isocyanate index" refers to the ratio of the number of equivalents of isocyanate functional groups to the number of equivalents of hydroxyl groups or active hydrogen groups in a given polyurethane-forming reaction mixture, multiplied by 100 and expressed as a number. For example, in a reaction mixture where the number of equivalents of isocyanate is equal to the number of equivalents of active hydrogen, the isocyanate index is 100.

[0028] As used herein, the term "weight-average molecular weight" refers to the weight-average molecular weight determined by 13C-NMR molecular identification and gel permeation chromatography (GPC) calibrated using polyether polyols such as polyethylene glycol.

[0029] As used herein, the term "polyisocyanate" refers to a substance containing isocyanate groups having two or more isocyanate functional groups, such as diisocyanates or their biurets, urethanes, isocyanurates, carbodiimides, dimers, trimers, or oligomers prepared by reacting an excess of isocyanate with one or more diols.

[0030] As used herein, the term "total solids" or "solids" refers to any substance in a given composition other than water and volatile solvents that flash off or evaporate at temperatures below 40°C and atmospheric pressure.

[0031] As used herein, the phrase "wt%" means weight percent.

[0032] As used herein, the phrase "vehicle" includes all types of vehicles such as, but not limited to, automobiles, minivans, SUVs (sport utility vehicles), trucks, over-the-road heavy trucks; tractors, buses, vans, golf carts, motorcycles, bicycles, trams, trailers, ATVs (all-terrain vehicles); minibuses; heavy mobile machines such as bulldozers, mobile cranes, and excavators; aircraft; boats; ships; and other means of transportation.

[0033] According to the present invention, the flexible polyurethane foam may include, for example, a semi-rigid polyurethane foam having a resilience of 40% to 65% as measured according to ASTM D3574-17 (2017). Suitable flexible polyurethane foams may be open-cell foams, for example, having a density of 200 g / L to 280 g / L or preferably 200 g / L to 260 g / L. Suitable flexible polyurethane foams may be formed as free-rise foams or molded foams. The open-cell foams according to the present invention may include cut pieces taken from a block or a molded foam, wherein the surface other than the skin is an open-cell foam.

[0034] The flexible polyurethane foam prepared according to the present invention may be formed from a reaction mixture comprising an isocyanate component and a polyol component. The isocyanate component is one or more aromatic polyisocyanates containing two or more aromatic or phenyl groups and an aromatic phosphorus-containing flame retardant, preferably a triaryl phosphorus-containing flame retardant containing three or more phenyl or aromatic groups; the polyol component includes: a mixture of one or more (preferably two or more) first polyols with one or more high molecular weight polyols, a flame retardant, one or more catalysts, and one or more blowing agents (preferably water). The first polyol has an average of 2.4 to 3.5 hydroxyl groups and a hydroxyl value of 26 mg KOH / g to 44 mg KOH / g according to ASTM D4274, for example 30 mg KOH / g to 40 mg KOH / g or 32 mg KOH / g to 37 mg KOH / g, such as a propoxylated polyol initiated with an ethylene oxide (EO)-capped triol (e.g., glycerol). The high molecular weight polyol has an average of 1.8 to 6 or preferably 3 to 5.2 hydroxyl groups and a hydroxyl value of 27 mg KOH / g to 38 mg KOH / g according to ASTM D4274, for example 31 mg KOH / g to 34 mg KOH / g, such as a propoxylated polyether polyol initiated with an EO-capped triol and a sugar alcohol. The flame retardant is a halogenated polyether polyol flame retardant, preferably a brominated polyether flame retardant having a bromine content of 30% to 40% by weight and an average hydroxyl functionality of 2.3 to 3.5. The reaction mixture may contain other reactants.

[0035] The aromatic polyisocyanates suitable for preparing the flexible polyurethane foam of the present invention may include any known di- or poly-aromatic diisocyanates or polyisocyanates having two or more phenyl or aryl groups, such as diphenylmethane diisocyanate (MDI) in its 2,4′-, 2,2′- or 4,4′-isomer forms and mixtures thereof. Preferably, the aromatic diisocyanates or polyisocyanates having two or more phenyl or aryl groups are selected from crude MDI, polymeric MDI or mixtures thereof, their prepolymers and mixtures containing up to 20 wt% or other ratios of aromatic polyisocyanates. As used herein, the term "crude MDI" or "polymeric MDI" (polymethylene polyphenylene polyisocyanate) refers to a mixture of diphenylmethane diisocyanate and its oligomers having an isocyanate functionality greater than 2, and may include known variants of MDI containing urethane, urethane, urea, biuret, carbodiimide, uretonimine and / or isocyanurate functional groups. Suitable carbodiimide- and / or uretonimine-modified polyisocyanates may include those disclosed, for example, in US Patent 6,765,034 B2 to Nishida et al.

[0036] Suitable crude MDI, polymeric MDI, combinations thereof and / or their liquid variants can be obtained by known methods for introducing uretonimine and / or carbodiimide groups into MDI (such as by reacting MDI and / or its carbodiimide with MDI, with its carbodiimide or with its biuret, its urethane and / or its isocyanurate). Other suitable crude MDI, polymeric MDI, combinations thereof and / or their liquid variants can be obtained by reacting MDI and / or its carbodiimide, biuret, urethane and / or isocyanurate with up to 10 wt% or preferably 2 wt% to 7 wt% of a diol or oligomeric diol chain extender (such as propylene glycol, dipropylene glycol or tripropylene glycol) to form an aromatic polyisocyanate prepolymer containing urethane. Suitable prepolymers can be formed from MDI, polymeric MDI or mixtures thereof with a diol chain extender such as one or more diols in an amount of 2 wt% to 7 wt% based on the weight of the reactants used to prepare the prepolymer. Such suitable crude MDI and / or (pre)polymeric MDI may have an NCO value of 28 wt% to 33 wt%, and may contain 30 wt% to 60 wt% of 2,4′-diphenylmethane diisocyanate in monomeric form. Preferably, the crude MDI and / or polymeric MDI materials comprise carbodiimide- and / or uretonimine-modified polyisocyanates having 30 wt% to 60 wt% monomeric MDI or more preferably 35 wt% to 55 wt% monomeric MDI.

[0037] Preferred examples of suitable isocyanate components include mixtures of 40 wt% to 60 wt% of monomeric diphenylmethane diisocyanate (monomeric MDI) in the form of the 2,4′-, 2,2′- or 4,4′-isomers with 40 wt% to 60 wt% of uretonimine of MDI or another polymeric MDI. More preferably, the mixture of monomeric MDI and polymeric MDI further comprises up to 10 wt% or preferably 2 wt% to 8 wt% of a chain extender selected from diols or oligomeric diols such as dipropylene glycol or tripropylene glycol. An example of a commercially available monomeric MDI can be ISONATE TM M 125 isocyanate (The Dow Chemical Co., Midland, MI). An example of a commercially available polymeric MDI can be ISONATE TM M 143 uretonimine (Dow).

[0038] In the present invention, in addition to and / or as an alternative to crude MDI, polymeric MDI and / or prepolymerized MDI, the aromatic polyisocyanate in the isocyanate component may include one or more aromatic polyisocyanates or cycloaliphatic polyisocyanates, provided that there is no adverse effect on the desired sound absorption and vibration management properties of the polyurethane foam. Typical examples of such other polyisocyanate compounds include isocyanate-terminated prepolymers formed by the reaction between at least one of the compounds of the above monomeric MDI compounds and a suitable active hydrogen compound. To improve the foaming properties and other characteristics of the obtained foam, additional polyisocyanates may be selected from toluene diisocyanate (TDI), isophorone diisocyanate (IPDI) and xylene diisocyanate (XDI) and their modified forms or oligomers, such as their prepolymers containing biuret, urethane, carbodiimide, isocyanurate and urethane. Suitable additional polyisocyanates may have an average isocyanate functionality of 2.1 to 3.0 or preferably 2.2 to 2.8.

[0039] The phosphorus flame retardant of the isocyanate component may include an alkyl-substituted aryl phosphate represented by the following general formula structure:

[0040]

[0041] Each R, R2, and R3 is independently hydrogen or a straight-chain or branched C1 to C4 alkyl group. Suitable alkyl-substituted aryl phosphates include tert-butylated triphenyl phosphate, isobutylated triphenyl phosphate, tricresyl phosphate, isopropylated triphenyl phosphate, and mixtures thereof. Depending on the degree of alkylation, such alkylated triaryl phosphates contain about 5.5 wt% to 9 wt% phosphorus. Preferably, the triphenyl phosphate is isopropyl phosphate or butyl triphenyl phosphate, where each ring contains 0, 1, or 2 butyl or isopropyl groups. An example of a suitable triaryl phosphorus-containing flame retardant is REOFOS TM 50 Flame retardant (Lanxess, Cologne, DE).

[0042] To ensure that the flexible polyurethane foam and any melt droplets therefrom are sufficiently self-extinguishing, suitable amounts of the aromatic polyisocyanate used to prepare the flexible polyurethane foam can be those amounts sufficient to provide an isocyanate index of 0.86 to 1.15 or preferably 0.89 to 1.12 or more preferably 0.89 to 1.11.

[0043] The polyol component of the reaction mixture according to the invention includes such polyol components that can include any polyol mixture of one or more first polyols and one or more high molecular weight polyols. The first polyol has an average of 2.4 to 3.5 hydroxyl groups, and the high molecular weight polyol has an average of 1.8 to 6 hydroxyl groups. The first polyol has a hydroxyl value of 26 mg KOH / g to 44 mg KOH / g according to ASTM D4274, or for example 30 mg KOH / g to 40 mg KOH / g or 32 mg KOH / g to 37 mg KOH / g, and can be, for example, a propoxylated polyol initiated with an ethylene oxide (EO)-capped triol (such as glycerol). The high molecular weight polyol can have an average of 1.8 to 6 or preferably 3 to 5.2 hydroxyl groups and a hydroxyl value of 27 mg KOH / g to 38 mg KOH / g according to ASTM D4274, or for example 31 mg KOH / g to 34 mg KOH / g, and can be, for example, a propoxylated polyether polyol initiated with an EO-capped triol and a sugar alcohol. Suitable first polyols can have a weight average molecular weight (GPC / NMR) of 2000 to 6000, and suitable high molecular weight polyols can have a weight average molecular weight (GPC / NMR) of 3000 to 10,000, preferably 4,000 to 8,500.

[0044] Suitable polyols are known in the prior art and can include reaction products of diols, glycols or alkylene oxides such as ethylene oxide and / or propylene oxide, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol or butylene glycol with initiators containing 2.4 to 6 active hydrogen atoms per molecule. Suitable initiators can include triols such as glycerol, trimethylolpropane or triethanolamine, and higher alcohols such as pentaerythritol, sorbitol and sugar alcohols such as sucrose; and mixtures of such initiators. Other suitable polyols can include polyamines or polyesters obtained by condensation of diols, glycols or alkylene oxides and higher functionality initiators containing 2.4 to 6 or 2.5 to 5.5 active hydrogen atoms per molecule with polycarboxylic acids to produce polyols having hydroxyl functional groups. Other suitable polyols include hydroxy-terminated polysulfides, polyamides, polyesteramides, polycarbonates, polyacetals, polyolefins and polysiloxanes, all of which are formed from initiators containing 2.4 to 5.5 active hydrogen atoms per molecule and diols, glycols or alkylene oxides. Other suitable polyols can include chain extenders selected from ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, ethylenediamine, ethanolamine, diethanolamine, triethanolamine and mixtures thereof in an amount of up to 5% by weight. Preferably, polyols that do not contain primary, secondary or tertiary nitrogen atoms are used.

[0045] Particularly important for the preparation of the flexible polyurethane foams of the present invention is a polyol mixture in which the hydroxyl equivalent weight of the first polyol is from 300 to 2000 and in which the hydroxyl equivalent weight of the high molecular weight polyol is from 1200 to 3000. As used herein, the term "polyol equivalent weight" or "hydroxyl equivalent weight" is the weight average molecular weight of the polyol divided by the average number of hydroxyl groups or the average hydroxyl functionality of the molecule.

[0046] Particularly important for the preparation of flexible polyurethane foams according to the invention are polyol mixtures which comprise the reaction product of one or more initiators with diols, diol ethers and / or alkylene oxides such as ethylene oxide and / or propylene oxide, preferably with alkylene oxides. Suitable diols have exactly two hydroxyl groups and a molecular weight of at most 15 or for example 62 to 150 or 62 to 125 or 62 to 100. Examples of diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, thiodiethanol, N-methyldiethanolamine and dipropylene glycol. Suitable initiators can contain 2.4 to 6 active hydrogen atoms per molecule. Suitable initiators can include, for example, glycerol, trimethylolpropane, triethanolamine, pentaerythritol, sorbitol and other sugar alcohols such as xylitol or mannitol; and mixtures of such initiators. Other suitable polyols include polyesters obtained by the condensation of suitable proportions of alkylene oxides, diol ethers and initiators with polycarboxylic acids. Further suitable polyols contain hydroxyl-terminated polysulphides, polyamides, polyesteramides, polycarbonates, polyacetals, polyolefins and polysiloxanes. Suitable polyols can have an ethylene oxide (ethylene oxide or polymerized ethylene glycol) weight % content of 10 wt% to 50 wt% or preferably 10 wt% to 30 wt%. Preferred isocyanate-reactive components include ethylene oxide-terminated initiators such as glycerol or mixtures of glycerol and sorbitol.

[0047] To obtain the desired molecular weight, the polyols in the present invention can be obtained by polymerizing propylene oxide onto the initiator and then terminating with ethylene oxide to provide primary hydroxyl groups. Thus, the initiator determines the number of polyether chains that can be ethylene oxide-terminated.

[0048] Preferably, the first polyol comprises an ethylene oxide-terminated propoxylated polyol having on average 2.4 to 3.5 hydroxyl groups or more preferably three hydroxyl groups, such as an ethylene oxide-terminated glycerol-initiated polyol. Based on the total number of hydroxyl groups, such a polyol can have 75% to 80% primary hydroxyl groups. The preferred first polyol can have a weight average molecular weight of 4200 to 5400.

[0049] The preferred high molecular weight polyol can have on average 4.5 to 5.4 hydroxyl groups and includes sugar alcohols and ethylene oxide-terminated glycerol-initiated propoxylated polyols. Based on the total number of hydroxyl groups, such a polyol can have 75% to 80% primary hydroxyl groups. The preferred high molecular weight polyol can have a weight average molecular weight of 5000 to 8500.

[0050] Another suitable high molecular weight polyol is the polyol component polyol SPECFLEX TMNC 702 Polyol (Dow): A styrene acrylonitrile copolymer composition in a polyether polyol carrier having a solids content of 39 wt% to 43 wt%, the carrier polyol being a triol-initiated, e.g., glycerol-initiated, propoxylated EO-capped polyether polyol having an average hydroxyl value of 20 mg KOH / g to 24 mg KOH / g.

[0051] To prepare a flexible polyurethane foam according to the present invention, the polyol mixture may comprise up to 99 wt% or up to 95 wt% or up to 94 wt% of the polyol component. Additionally, based on the total weight of the polyol component in the reaction mixture, the polyol mixture may account for 90 wt% or more or 92 wt% or more.

[0052] The polyol component of the reaction mixture according to the present invention includes a halogenated polyether polyol flame retardant, preferably a brominated polyether polyol flame retardant having an average hydroxyl functionality of 2.3 to 3.5. Suitable halogenated polyether polyols may include the reaction product of a brominated triol or a mixture of a brominated diol and a brominated triol with epichlorohydrin. An example of such a halogenated polyether polyol is a flame retardant sold as IXOL TM B-251 Polyol (Solvay, Brussels, BE).

[0053] Such a brominated polyether polyol flame retardant may have the following formula, where x plus y equals 2.3 to 3.5:

[0054]

[0055] The polyol component of the reaction mixture for preparing the flexible polyurethane foam of the present invention may also include one or more catalysts. Suitable catalysts may be primary amine catalysts, secondary amine catalysts, tertiary amine catalysts, reactive amine catalysts or mixtures thereof, preferably tertiary amine catalysts. The catalyst may be any compound having catalytic activity for the reaction between the polyol and the aromatic polyisocyanate and having at least one amine group. Representative catalysts may include tertiary amines, including trimethylamine, triethylamine, dimethylethanolamine, N-methylmorpholine, N-ethylmorpholine, N,N-dimethylbenzylamine, N,N-dimethylethanolamine, N,N,N′,N′-tetramethyl-1,4-butanediamine, N,N-dimethylpiperazine, 1,4-diazabicyclo-2,2,2-octane, bis(dimethylaminoethyl) ether, bis(2-dimethylaminoethyl) ether, 4,4′-(oxydi-2,1-ethanediyl)bismorpholine, triethylenediamine, pentamethyldiethylenetriamine, dimethylcyclohexylamine, N-acetyl-N,N-dimethylamine, N-cocomorpholine, N,N-dimethylaminomethyl-N-methylethanolamine, N,N,N′-trimethyl-N′-hydroxyethylbis(aminoethyl) ether, N,N-bis(3-dimethylaminopropyl)N-isopropanolamine, (N,N-dimethyl)amino-ethoxyethanol, N,N,N′,N′-tetramethylhexanediamine, 1,8-diazabicyclo-5,4,0-undecene-7, N,N-dimorpholinodiethyl ether, N-methylimidazole, dimethylaminopropyldipropanolamine, bis(dimethylaminopropyl)amino-2-propanol, tetramethylaminobis(propylamine), (dimethyl(aminoethoxyethyl))((dimethylamine)ethyl) ether, tris(dimethylaminopropyl)amine, dicyclohexylmethylamine, bis(N,N-dimethyl-3-aminopropyl)amine, 1,2-ethylenepiperidine and methyl-hydroxyethylpiperazine. Suitable amine catalysts may include bis(N,N-dimethylaminoethyl) ether or a mixture of bis(N,N-dimethylaminoethyl) ether (70%) and 1,4-diazabicyclo-2,2,2-octane. Examples of reactive amine catalysts include 1,1′-[[3-(dimethylamino)propyl]imino]bis-2-propanol, N-1-[2-[2[(dimethylamino)ethoxy]ethyl]-N-1-methyl-1,3-propanediamine, 2-[[2-[2-(dimethylamino)ethoxy]ethyl]methylaminoethanol, N-3-[3-(dimethylamino)propyl]-N-1,N-1-dimethyl-1,3-propanediamine and DEOA.

[0056] Examples of amine catalysts that can be used in the polyol component of the present invention may include those obtained as the following catalysts: DABCO TM NE 300 - N,N,N′-trimethyl-N′-3-aminopropyl-bis(aminoethyl) ether catalyst (Evonik Industries, Inc, Essen, DE), DABCO TMNE 1095 catalyst (Evonik) - a blend of 1 wt% to 10 wt% of N-[2-[2-(dimethylamino)ethoxy]ethyl]-N-methyl-1,3-propanediamine and the balance of 6-dimethylaminohexan-1-ol, JEFFCAT TM DMDEE catalyst - 2,2′-dimorpholinodiethylether (Huntsman, The Woodlands, TX), JEFFCAT TM DM-70 catalyst (Huntsman) - which is 63 wt% to 84 wt% of 2,2′-dimorpholinodiethylether, 13 wt% to 30 wt% of 1,4-dimethylpiperazine, and 3 wt% to 7 wt% of 4,4′-(ethane-1,2-diyl)bismorpholine.

[0057] In addition to the amine catalysts, the polyol component of the reaction mixture for preparing the flexible polyurethane foam of the present invention may also contain one or more secondary catalysts. Of particular interest among these secondary catalysts are tin carboxylates and tetravalent tin compounds. Examples of these catalysts include stannous octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dithiolate, dialkyltin dialkyl mercaptoacetates, dibutyltin oxide, dimethyltin dithiolate, dimethyltin diisooctyl mercaptoacetate, etc.

[0058] Based on the total weight of the polyol component, the catalyst can be used, for example, in an amount of 0.002 wt% to 5 wt% or preferably 0.01 wt% to 1 wt%. If used, based on the total weight of the polyol component, the organometallic catalyst can be used in an amount of 0.001 wt% to 0.5 wt%.

[0059] To allow for better hardness control in the foam, a chain extender can be employed as an additional ingredient in the polyol component of the reaction mixture for preparing the flexible polyurethane foam of the present invention. The chain extender can include diols, alkoxylated diols, or polyols having one or two isocyanate-reactive groups and an equivalent weight of each isocyanate-reactive group of at most 499 or at most 250. Based on the total weight of the polyol component, if present, the chain extender is typically used in a small amount such as at most 10 wt% or preferably 1 wt% to 5 wt%. Examples of suitable chain extenders include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-bis(hydroxymethyl)cyclohexane, 1,4-butanediol, 1,6-hexanediol, 1,3-propanediol, diethyltoluenediamine, amine-terminated polyethers such as JEFFAMINE TMD-400 polyether (Huntsman Chemical Company, Salt Lake City, UT), aminoethyl piperazine, 2-methyl piperazine, 1,5-diamino-3-methyl-pentane, isophorone diamine, ethylenediamine, hexamethylenediamine, hydrazine, piperazine, mixtures thereof, etc. A methoxydiol in an amount of 1 wt% to 5 wt% based on the total weight of the polyol component can achieve improved hardness control in flexible polyurethane foams.

[0060] In the reaction mixture of the present invention, the polyol component may further include any one of a surfactant, a crosslinking agent for aromatic polyisocyanates, a filler, a colorant, a pigment, an antistatic agent, a reinforcing fiber, an antioxidant, or a preservative. For example, the colorant may be present in an amount of 0.5 wt% to 2 wt% based on the total weight of the polyol component.

[0061] In the reaction mixture of the present invention, the isocyanate component may further include any one of a surfactant, a chain extender, a filler, a colorant, a pigment, an antistatic agent, a reinforcing fiber, an antioxidant, a preservative, or an acid scavenger.

[0062] It has been found that a polyurethane foam reaction mixture containing a mixture of a first polyol and a high molecular weight polyol in a ratio of 15 wt% to 35 wt% first polyol to 65 wt% to 85 wt% high molecular weight polyol based on the total weight of the first polyol and the high molecular weight polyol can achieve good processability, especially in a formulation where water is used as a blowing agent, especially when used as the sole blowing agent. As used herein, the term "good processability" refers to the effect of consistently producing foams of acceptable quality in an industrial environment using the reaction mixture. Good processability is indicated by the uniformity of the pore structure, open cell formation, complete mold filling, surface appearance, foam density, and physical properties as the foam is produced over time. The reaction mixture should tolerate small variations in operating temperature, catalyst level, and other process conditions, which typically result in significant product inconsistencies in high water content reaction mixtures.

[0063] [[ID=1Z]]The open cell flexible polyurethane foam according to the present invention can be prepared in a slabstock process or in a closed mold molding process. Block foams can be formed into large round blocks, which are cut into the desired shapes and sizes for use. The closed mold molding process may include a hot molding process or a cold molding process, where foaming occurs in a closed mold. After the foam has cured, the mold is opened, and the foam is removed. If a self-skin forms on the surface of the foam in the mold, the skin can be removed, such as by cutting.

[0064] According to the present invention, a method for preparing a flexible polyurethane foam comprises forming a reaction mixture which, upon mixing, allows a foaming reaction to occur by mixing an isocyanate component with a polyol component and allowing the resulting reaction mixture to form a foam, the isocyanate component being one or more aromatic polyisocyanates containing two or more aromatic or phenyl groups and an aromatic phosphorus-containing flame retardant, preferably a triaryl phosphorus-containing flame retardant containing three or more phenyl or aromatic groups; the polyol component comprising a mixture of one or more (preferably two or more) first polyols with one or more high molecular weight polyols, a flame retardant, one or more catalysts and one or more blowing agents (preferably water), the first polyol having an average of 2.4 to 3.5 hydroxyl groups and a hydroxyl value of 26 mg KOH / g to 44 mg KOH / g according to ASTM D4274 or for example 30 mg KOH / g to 40 mg KOH / g or 32 mg KOH / g to 37 mg KOH / g, the high molecular weight polyol having an average of 3.6 to 6 hydroxyl groups and a hydroxyl value of 27 mg KOH / g to 38 mg KOH / g according to ASTM D4274 or for example 31 mg KOH / g to 34 mg KOH / g, such as an EO-capped triol and a propoxylated polyether polyol initiated with a sugar alcohol, the flame retardant being a halogenated polyether polyol flame retardant, preferably a brominated polyether flame retardant having a bromine content of 30 wt% to 40 wt% and an average hydroxyl functionality of 2.3 to 3.5. The method may also comprise heating the polyol component to 40 °C or 25 °C to 35 °C, or then mixing it with the isocyanate component.

[0065] For the flexible polyurethane foam according to the present invention, the foam may or may not be crushed to open the pores. An open cell content of at least 25% or preferably at least 50% of the pores provides a foam suitable for noise and vibration absorption applications.

[0066] The flexible polyurethane foam of the present invention may have one or more or preferably all of the following parameters: a compressive stress resistance (DIN EN ISO 3386-1 (1986)) of 15 kPa to 100 kPa and at least 50% of this value after thermal ageing at 150 °C for 168 h or after ageing at 90 °C and 95% relative humidity for 200 h; a tensile strength (DIN EN ISO 1798 (1997)) of at least 150 kPa and at least 40% of this value after thermal ageing at 150 °C for 168 h or after ageing at 90 °C and 95% relative humidity for 200 h; and a compression set (DIN EN ISO 1856 (2007)) of 50% and an initial compression set of at least 60% after 22 h at 150 °C.

[0067] Depending on the composition of the polyol component, a high temperature above 40 °C may be required to form the reaction mixture. Preferably, the polyol component is mixed with the isocyanate component at a temperature below 40 °C or more preferably from 20 °C to 30 °C. The polyol component and the isocyanate component can be mixed together by any known polyurethane foaming equipment.

[0068] Subject the resulting reactive formulation to conditions sufficient to cure the reactive formulation to form a flexible polyurethane foam. Alternatively, introduce the reactive formulation into a suitable mold such that the foaming / curing reaction occurs within the mold to form the desired polyurethane foam, or allow the reactive formulation to foam / cure to form a block board, or cause the reactive formulation to foam in place.

[0069] The self-extinguishing flexible polyurethane foam of the present invention can be suitably used for high heat applications such as noise and vibration absorption applications, for example, for sound insulation in the engine compartment, fuel injectors, oil pans, covers, shield mufflers, seat cushions, partitions, doors, roofs or instrument panels of vehicles. In addition, the flexible polyurethane foam can be used and / or molded into articles to be used and / or to be molded / foamed in place as hoods, engine acoustic covers, fuel injector encapsulation materials, side covers, oil pan covers, covers, shield mufflers and instrument panel mufflers to reduce the amount of sound or noise transmitted in the passenger compartment of the vehicle. In addition, the flexible polyurethane foam can be suitably used and / or molded into articles to be used or to be molded / foamed in place for filling the gaps or spaces between the passenger cab or fuselage and the engine or surrounding vehicle components such as tires, wheels or wings or for encapsulating engine components or injection ports for heat insulation and / or for reducing waves or noise emitted from the engine block, gearbox, differential, exhaust system, radiator fan, engine muffler, propeller or injection port.

[0070] Example

[0071] The following examples are used to illustrate the present application. Unless otherwise specified, all temperatures are ambient temperatures (21 °C to 23 °C), all pressures are 1 atmosphere, and the relative humidity (RH) is 35%. Although the numerical ranges and parameters that set forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value inherently contains certain errors determined by the standard variations that exist in their respective test measurements.

[0072] The materials used in the following examples are set forth in Table 1 below. Each polyol in Table 1 below has a certain hydroxyl equivalent weight (HEW), a functionality (F) which is the number of hydroxyl groups in the given polyol, a weight percent of ethylene oxide (EO%), and an initiator. As used herein, the term "HEW" refers to the hydroxyl equivalent weight of the polyol. Each polyol is prepared by the reaction of a polyol initiator with ethylene oxide (EO) and / or propylene oxide (PO), and the polyol initiator can be a diol, triol or sugar alcohol and determines the functionality of the polyol.

[0073] Flexible polyurethane foams are prepared by mixing the polyol component and the isocyanate component of the reaction mixtures listed in Tables 2 and 3 below separately in a drum and then mixing appropriately using an automatic stirrer.

[0074] The production of the foam parts is carried out by a high-pressure (molding) machine, such as a machine equipped with a 14 mm FPL (L-shaped mixing chamber) mixing head. The reaction mixture of the polyol and the isocyanate is poured into a 400 mm × 500 mm × 20 mm mold heated by water recirculation and treated with a water-based release agent. The temperature of the mold is set to 55 °C to 60 °C, the pressure is about 140 bar, and the temperature is about 25 °C to 35 °C. After 2 minutes, the indicated composition is demolded and then tested as indicated.

[0075] Viscosity : Refer to the results obtained at 20 °C using a cone-plate rheometer equipped with a 50 mm plate according to ASTM D4287 (2019). The acceptable viscosity range is from 1700 mPa*s to 3000 mPa*s at 20 °C.

[0076] Measured according to ASTM D5155 (2019) Free isocyanate content .

[0077] Total density (DIN EN ISO 845 (2009)): Measure the foam density. The acceptable range is 200 or 275 or preferably 200 to 250 Kg / m 3 or g / l.

[0078] Compressive stress (DIN EN ISO 3386-1 (2010)): Measure the hardness of the foam in compression. The acceptable range is 15 kPa - 100 kPa. After thermal aging at 150 °C kPa for 168 h, the acceptable result is ≥ 50% of the average value of the initial conditions. After damp heat aging at 90 °C and 95% relative humidity for 200 h, the acceptable result is ≥ 50% of the average value of the initial conditions.

[0079] Tensile strength and elongation at break(DIN EN ISO 1798(2008)): Acceptable result ≥ 150 kPa. After thermal aging at 150 °C kPa for 168 h, the acceptable result is ≥ 40% of the average value of the initial conditions. After damp heat aging at 90 °C and 95% relative humidity for 200 h, the acceptable result is ≥ 40% of the average value of the initial conditions.

[0080] 50% Compression set (DIN EN ISO 1856(2018)) ≤ 60% of the initial conditions after 22 h at 150 °C.

[0081] Table 1: Composition of flexible polyurethane foam composition

[0082]

[0083] 1. IXOL TM Flame retardant B-251 (SOLVAY, Brussels, BE); 2. IXOL TM Flame retardant M-125 (SOLVAY); 3. NERO REPITAN / IN 99375 Repi SPA (Maggiore, IT); 4. NIAX TM Catalyst A1 (Momentive Performance Chemicals, Philadelphia, PA); 5. Catalyst 33-LV (Evonik, Essen, DE); 6. Dow; 7. REOFOS TM Flame retardant 50 (Lanxess, Cologne, DE).

[0084] Flammability (MVSS 302) and self-extinguishing fire or dripping test (PV 3357, Volkswagen, Wolfsburg, DE, 2017): Flammability is measured by the response of the foam block after exposing the surface and edges to a flame with a Bunsen burner; additionally, self-extinguishability is measured by a drop test. Before testing, condition the blocks at 23 °C ± 2 °C and 50% ± 5% RH for 7 days. In Flammability test , clamp a 230 mm × 230 mm × 22 mm block in a horizontal clamping position and set the burner in a vertical position 100 mm below the block with a flame height of 100 mm. The distance between the top of the burner and the block surface is 90 mm. The test is divided into a short-term exposure of 15 s and a long-term flame exposure of 5 min. After each exposure, turn off the gas supply and evaluate the sample. In the flammability test, the foam may have been burned through, but it must not drip or continue to burn after the flame is removed. Record the flammability as the number of seconds at which self-extinguishment occurs regardless of the flame exposure time, and the diameter of the damaged area must not be greater than 150 mm. If the foam drips during combustion, perform Dripping test, in which a foam block with a minimum size of 160 mm × 200 mm × 22 mm is clamped into a horizontal position above the cotton ball layer, the burner is placed at a 45° angle relative to the block, and the flame height is controlled in such a way that the flame penetrates the block by 10 mm. A layer of 100% absorbent cotton balls of 10 g ± 5 g is manually fluffed and evenly distributed in an open tempered glass cylinder with an inner diameter of 100 mm, and then it is subjected to a load for 1 minute using a 5 kg round plunger. After removing the load, the cotton layer is placed approximately 140 mm below the foam block. Then the foam block is burned for 15 seconds. The molten droplets cannot ignite the cotton balls. Three tests are conducted for each tested foam, and the results are averaged. Record the self-extinguishing time or the amount of time any foam continues to burn after removing the flame.

[0085] Table 2: Fire test and foam formulation

[0086]

[0087] 1. P = Pass; F = Fail.

[0088] Table 3: Comparative flexible foam formulation

[0089]

[0090] 1. P = Pass; F = Fail.

[0091] As shown in Table 2, all of the above flexible polyurethane foams of the present invention achieved passing results in the self-extinguishing fire test (including self-extinguishing dripping) within a wide range of flame retardant concentrations. Only Example B at an isocyanate index of 90 failed the test, where the foam dripped during the flammability test. In contrast, the comparative flexible polyurethane foam failed the self-extinguishing fire test, where, as in Comparative Example H, the reaction mixture did not contain brominated polyol. In Comparative Example I, the flexible polyurethane foam from the reaction mixture containing a brominated polyether polyol flame retardant with an average hydroxyl functionality of 2 failed the self-extinguishing fire test. In Comparative Examples K and L, the brominated polyether polyol flame retardants with proportions lower than the scope of the present invention failed the self-extinguishing fire test.

Claims

1. A flexible polyurethane foam-forming reaction mixture comprising: an isocyanate component, which is one or more aromatic polyisocyanates or their prepolymers containing two or more aromatic groups and 12% to 27% by weight of an aromatic phosphorus-containing flame retardant based on the weight of the isocyanate component; and a polyol component, which is a mixture of one or more first polyols, one or more high molecular weight polyols, a brominated polyether flame retardant, one or more catalysts, and one or more blowing agents. The one or more first polyols have an average of 2.4 to 3.5 hydroxyl groups and a hydroxyl value of 26 mg KOH / g to 44 mg KOH / g according to ASTM D4274. The one or more high molecular weight polyols have an average of 4.5 to 6 hydroxyl groups and a hydroxyl value of 27 mg KOH / g to 38 mg KOH / g according to ASTM D4274. The brominated polyether flame retardant is 7.5% to 17.5% by weight based on the weight of the polyol component, has a bromine content of 30% to 40% by weight, and an average hydroxyl functionality of 2.3 to 3.

5. The amount of the one or more blowing agents ranges from 1.0% to 1.3% by weight based on the total weight of the polyol component of the reaction mixture, wherein the relative amounts of the isocyanate component and the polyol component in the reaction mixture are sufficient to provide an isocyanate index of 0.86 to 1.

15.

2. The flexible polyurethane foam-forming reaction mixture according to claim 1, wherein the isocyanate component comprises diphenylmethane diisocyanate (MDI) in the form of its 2,4'-MDI isomer monomer, 2,2'-MDI isomer monomer, or 4,4'-MDI isomer monomer; polymeric MDI, which is the uretonimine, urethane, biuret, or isocyanurate of MDI; or a mixture thereof.

3. The flexible polyurethane foam-forming reaction mixture according to claim 2, wherein the isocyanate component comprises a mixture of 40% to 60% by weight of monomeric MDI and 40% to 60% by weight of polymeric MDI based on the weight of the isocyanate component.

4. The flexible polyurethane foam-forming reaction mixture according to claim 1, wherein the isocyanate component comprises a triaryl phosphorus-containing flame retardant containing three aromatic groups.

5. The flexible polyurethane foam-forming reaction mixture according to claim 1, wherein the polyol component comprises 55% to 70% by weight of the one or more first polyols and 13% to 30% by weight of the one or more high molecular weight polyols based on the weight of the polyol component.

6. The flexible polyurethane foam-forming reaction mixture according to claim 5, wherein the high molecular weight polyol has an average of 4.5 to 5.2 hydroxyl groups.

7. A flexible polyurethane foam-forming reaction mixture according to any one of claims 1 to 6, wherein the catalyst in the polyol component comprises a primary amine.

8. A flexible polyurethane foam-forming reaction mixture according to any one of claims 1 to 6, wherein the blowing agent comprises water.

9. A flexible polyurethane foam-forming reaction mixture according to any one of claims 1 to 6, wherein the polyol component further comprises any amine gelling catalyst in an amount of 0.1% to 1% by weight based on the total weight of the polyol component.

10. A flexible polyurethane foam-forming reaction mixture according to any one of claims 1 to 6, wherein the aromatic group is a phenyl group.

11. A flexible polyurethane foam comprising an open-cell foam in the form of a foamed polyurethane having a total density of 200 g / L to 280 g / L according to D4274 DIN EN ISO 845, and comprising an aromatic polyurethane containing two or more aromatic groups and an aromatic phosphorus-containing flame retardant in an amount of 6% to 14% by weight based on the weight of the foamed polyurethane; and further comprising a polyol in the form of a polyurethane, which is a mixture of one or more first polyols, one or more high molecular weight polyols, and a brominated polyether flame retardant, the one or more first polyols having an average of 2.4 to 3.5 hydroxyl groups in the form of urethane and a hydroxyl value of 26 mg KOH / g to 44 mg KOH / g according to ASTM D4274, the one or more high molecular weight polyols having an average of 4.5 to 6 hydroxyl groups in the form of urethane and a hydroxyl value of 27 mg KOH / g to 38 mg KOH / g according to ASTM D4274, the brominated polyether flame retardant being 3.7% to 9% by weight based on the weight of the foamed polyurethane and having a bromine content of 30% to 40% and an average hydroxyl functionality in the form of urethane of 2.3 to 3.

5.

12. The flexible polyurethane foam according to claim 11, wherein the aromatic group is a phenyl group.

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