Water-blown, environmentally friendly, high-yield spray polyurethane foam

Abstract

The present invention provides a method for producing a polyurethane foam at a concentration of 5 to 20 g / dm by mixing (a) a polyisocyanate containing PMDI, (b) a compound having at least two hydrogen atoms reactive with an isocyanate group, the compound including (b1) at least one polyether polyol obtained by alkoxylation of a di- or trifunctional starter molecule having a hydroxyl value of 210 to 400 mg KOH / g, and (b2) at least one polyether polyol obtained by alkoxylation of an aliphatic diamine, (c) a catalyst including (c1) at least one incorporateable amine catalyst, and (c2) at least a catalyst including a urea structure, (d) a blowing agent including water, (e) optionally a flame retardant, and (f) optionally an auxiliary and additional substance to obtain a reaction mixture, spraying the reaction mixture onto a substrate, and curing the reaction mixture to obtain a polyurethane foam. 3 wherein the reaction mixture comprises less than 1 part by weight of a phosphorus-based flame retardant. The present invention further relates to polyurethane foams obtainable by the process according to the invention.

Description

[Technical Field]

[0001] The present invention provides a method for producing a polyurethane foam at a concentration of 5 to 20 g / dm by mixing (a) a polyisocyanate comprising PMDI, (b) a compound having at least two hydrogen atoms reactive with isocyanate groups, the compound comprising (b1) at least one polyether polyol obtained by alkoxylation of a di- or trifunctional starter molecule having a hydroxyl number of 210 to 400 mg KOH / g, and (b2) at least one polyether polyol obtained by alkoxylation of an aliphatic diamine, (c) (c1) a catalyst comprising at least one incorporateable amine catalyst, (d) a blowing agent comprising water, (e) optionally a flame retardant, and (f) optionally an auxiliary and additional substance to obtain a reaction mixture, spraying the reaction mixture onto a substrate, and curing the reaction mixture to obtain a polyurethane foam. 3 wherein the reaction mixture comprises less than 1 part by weight of a phosphorus-based flame retardant. The present invention further relates to polyurethane foams obtainable by the process according to the invention.

[0002] Numerous publications in the patent and other literature describe the known production of polyurethane foams, especially rigid polyurethane foams, by the reaction of polyisocyanates with compounds having at least two hydrogen atoms reactive towards isocyanate groups, especially polyether polyols from alkylene oxide polymerization or polyester polyols from the polycondensation of alcohols and dicarboxylic acids, in the presence of polyurethane catalysts, blowing agents and other auxiliaries and additional substances.

[0003] Polyurethane spray foam is a polyurethane foam that is applied directly in place by spraying. This also allows for vertical application and overhead applications, for example. The main applications of polyurethane spray foam are found in the construction industry, acoustic absorption, or thermal insulation, such as roof insulation.

[0004] The key requirements for polyurethane spray foams are low thermal conductivity and / or good acoustic absorption, low viscosity for good flow and sprayability, and fast reactivity to prevent dripping, sufficient foam adhesion to a wide variety of substrates, low density, and good mechanical properties. Polyurethane foams are typically produced by the so-called two-component process, which involves mixing an isocyanate component containing an isocyanate with a polyol component containing an isocyanate-reactive component. Other starting materials, such as blowing agents and catalysts, are typically added to one of the components.

[0005] An additional requirement for spraying foams, especially when they are used in enclosed spaces, such as the interior of buildings, is the need to reduce volatile organic compound (VOC) emissions. To ensure fast reaction and prevent dripping, especially when chemical blowing agents such as water are used, additional catalysts are required. Amine catalysts are known to contribute to VOC emissions. Therefore, these catalysts are replaced by reactive amine catalysts that contain isocyanate-reactive groups and can therefore be incorporated into the polyurethane network. The disadvantage of these catalysts is their low activity, which requires a larger amount of catalyst. Nevertheless, a larger amount of amine catalyst results in higher corrosivity of the polyol component.

[0006] The polyurethane foam industry is known to use chemical and / or physical blowing agents to expand polymers to form polyurethane foam. Chemical blowing agents react with isocyanate functional groups to form gases, while physical blowing agents have lower boiling points and are therefore converted to a gaseous state by the heat of reaction. Chemical and physical blowing agents are typically added to the polyol component.

[0007] The physical blowing agents primarily used to date have included chlorofluorocarbons. Physical blowing agents are often used to improve the sprayability of the polyol and polyol / isocyanate reaction mixtures by reducing their viscosity. However, these are now banned in many parts of the world due to their damaging effects on the ozone layer. The primary physical blowing agents used today include fluorocarbons, HFCs, and low-boiling hydrocarbons such as pentane. The shelf life of each component is a key criterion, as is the flammability of the hydrocarbons. Furthermore, HFCs are expensive. Therefore, there was a need to at least partially replace physical blowing agents.

[0008] Another approach to reducing viscosity is to add a liquid flame retardant, such as a phosphorus-based flame retardant like TCPP. The addition of TCPP has the drawback of forming significant amounts of 1,2-dichloropropane, which is classified as a carcinogenic VOC. Replacing TCPP is not easy, as many of the inert substances that reduce the viscosity of the reaction mixture slowly migrate out of the foam, resulting in VOC emissions.

[0009] An object of the present invention was to provide a very low density polyurethane spray foam having good mechanical properties, particularly dimensional stability, and low volatile organic compound emissions, particularly no 1,2-dichloropropane emissions. A further object was to provide a method for producing spray foam in which the reaction is fast enough to prevent dripping, the polyol component is non-corrosive, and the polyol component and reaction mixture have low viscosity.

[0010] The object of the present invention is to provide a polyurethane foam having a density of 5 to 20 g / dm3 obtained by a process comprising mixing (a) a polyisocyanate comprising PMDI; (b) a compound having at least two hydrogen atoms reactive with isocyanate groups, the compound comprising (b1) at least one polyether polyol obtained by alkoxylation of a di- or trifunctional starter molecule having a hydroxyl number of 210 to 400 mg KOH / g, and (b2) at least one polyether polyol obtained by alkoxylation of an aliphatic diamine; (c) a catalyst comprising (c1) at least one incorporateable amine catalyst; (d) a blowing agent comprising water; (e) optionally a flame retardant; and (f) optionally an auxiliary and additional substance to obtain a reaction mixture, spraying the reaction mixture on a substrate, and curing the reaction mixture to obtain a polyurethane foam. 3 wherein the reaction mixture comprises less than 1 part by weight of a phosphorus-based flame retardant. The present invention further relates to a process for producing the polyurethane foam according to the present invention.

[0011] The present invention relates to polyurethane spray foam that is applied in situ by spraying directly onto a substrate, the substrate being, for example, part of a building, such as a wall or ceiling.

[0012] The polyisocyanate (a) used includes polymeric diphenylmethane diisocyanate. Diphenylmethane diisocyanate is also referred to hereinafter as "MDI." Polymeric MDI is a mixture of MDI containing two aromatic rings and MDI homologs containing more aromatic rings, such as homologs containing three, four, or five aromatic rings, i.e., tri-, tetra-, or penta-functional isocyanates. Polymeric MDI can be used together with other diisocyanates conventionally used in polyurethane chemistry, such as toluene diisocyanate (TDI) or naphthalene diisocyanate (NDI). The diisocyanate preferably contains at least 80% by weight of diphenylmethane diisocyanate, particularly preferably at least 90% by weight of diphenylmethane diisocyanate, in each case based on the total weight of the diisocyanate, and in particular exclusively diphenylmethane diisocyanate. The viscosity of the polyisocyanate (a) at 25° C. is preferably 250 mPas to 1000 mPas, more preferably 300 mPas to 800 mPas, particularly preferably 400 mPas to 700 mPas, and particularly preferably 450 mPas to 550 mPas.

[0013] The compounds (b) used having isocyanate-reactive groups can include all known compounds having at least two hydrogen atoms reactive with isocyanates, such as compounds with a functionality of 2 to 8 and a number-average molar mass of 62 to 15,000 g / mol. For example, polyether polyols can be used, the molar mass of which is preferably 200 to 15,000 g / mol. It is also possible to use low-molecular-weight chain extenders and / or crosslinkers together with the polyether polyols. For the purposes of this disclosure, the terms "polyether polyol" and "polyether polyol" are equivalent.

[0014] Polyetherols are prepared, for example, from epoxides such as propylene oxide and / or ethylene oxide or from tetrahydrofuran using catalysts containing active hydrogen, such as aliphatic alcohols, phenols, amines, carboxylic acids, water, or compounds based on natural materials, such as sucrose, sorbitol, or mannitol. Examples of catalysts that can be mentioned here include basic catalysts or double metal cyanide catalysts, as described in International Application PCT / EP2005 / 010124, EP 0090444, or WO 05 / 090440.

[0015] Component (b) can further contain a chain extender and / or crosslinker, for example, to modify mechanical properties such as hardness. The chain extenders and / or crosslinkers used include diols and / or triols, and amino alcohols, having a molar mass of less than 200 g / mol, preferably 60 to 150 g / mol. Examples include difunctional alcohols such as monoethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, tetraethylene glycol, dipropylene glycol, and cyclohexanediol, as well as aliphatic or aromatic amine-based chain extenders, such as ethylenediamine, triethylenediamine, and / or diethyltoluenediamine (DETDA). Likewise, it is also possible to use aliphatic and cycloaliphatic triols such as glycerol, trimethylolpropane and 1,2,4- and 1,3,5-trihydroxycyclohexane.

[0016] To the extent that chain extenders, crosslinkers or mixtures thereof are used in the preparation of rigid polyurethane foams, the amount advantageously used thereof is 0 to 15% by weight, preferably 0 to 5% by weight, based on the total weight of component (b).

[0017] In the present invention, the compound (b) having at least two hydrogen atoms reactive with isocyanate groups includes (b1) at least one polyether polyol obtained by alkoxylation of a di- or trifunctional starter molecule having a hydroxyl value of 210 to 400 mg KOH / g, and (b2) at least one polyether polyol obtained by alkoxylation of an aliphatic diamine.

[0018] In a preferred embodiment, the compound (b) may further comprise at least one aliphatic or aromatic diamine chain extender (b3). Preferably, the aliphatic or aromatic diamine chain extender (b3) is diethyltoluenediamine.

[0019] In a preferred embodiment of the present invention, the compound (b) comprises at least one polyether polyol (b4) obtainable by alkoxylation of a di- or trifunctional starter molecule having a hydroxyl number of 20 to 50 mg KOH / g and / or at least one polyether polyol (b5) obtainable by alkoxylation of a di- or trifunctional starter molecule having a hydroxyl number of 100 to less than 210 mg KOH / g.

[0020] In a preferred embodiment, the polyether polyol (b1) is propylene glycol having a hydroxy value of preferably 215 to 350 mg KOH / g, more preferably 220 to 300 mg KOH / g.

[0021] In a further preferred embodiment, polyol (b2) is obtainable by propoxylation of ethylenediamine, preferably having an OH number of 350 to 550 mg KOH / g, more preferably 420 to 520 mg KOH / g.

[0022] In a further preferred embodiment, polyol (b4) is obtainable by propoxylation and ethoxylation of difunctional starter molecules, preferably having an OH number of 20 to 50 mg KOH / g, more preferably 25 to 30 mg KOH / g.

[0023] In a further preferred embodiment, polyol (b5) is obtainable by alkoxylation of a difunctional starter molecule with ethylene oxide, preferably having an OH number of 120 to 200 mg KOH / g, more preferably 150 to 200 mg KOH / g.

[0024] It is particularly preferred that the compound having at least two hydrogen atoms reactive with isocyanate groups (b) comprises polyols (b1), (b2), (b3), (b4), and (b5). In a particularly preferred embodiment, the content of polyol (b1) is 5 to 30% by weight, preferably 10 to 20% by weight, based on the total weight of the compounds (b), each having at least two hydrogen atoms reactive with isocyanate groups, the content of polyol (b2) is 5 to 30% by weight, preferably 12 to 25% by weight, the content of polyol (b3) is 0.5 to 5% by weight, preferably 1.5 to 2.5% by weight, the content of polyol (b4) is 30 to 60% by weight, preferably 40 to 55% by weight, and the content of polyol (b5) is 5 to 30% by weight, preferably 12 to 25% by weight. In an even more preferred embodiment, the content of polyols (b1) to (b5) is at least 80% by weight, more preferably at least 90% by weight, particularly preferably at least 95% by weight, and in particular 100% by weight, based on the total weight of compound (b).

[0025] The catalyst (c) significantly accelerates the reaction of the compound (b) having at least two hydrogen atoms reactive with isocyanate groups and the chemical blowing agent (d) with the polyisocyanate (a). Typical catalysts are strongly basic amines. The catalyst (c) preferably includes an incorporable amine catalyst (c1).

[0026] Typical catalysts that can be used in the production of polyurethanes include amidines such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, N-methyl-, N-ethyl-, and N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutanediamine, N,N,N',N'-tetramethylhexanediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis(dimethylaminopropyl)urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo[3.3.0]octane, preferably 1,4-diazabicyclo[2.2.2]octane, and alkanolamine compounds such as triethanolamine, triisopropanolamine, N-methyl- and N-ethyldiethanolamine, and dimethylethanolamine. Organometallic compounds, preferably organotin compounds, such as tin(II) salts of organic carboxylic acids, such as tin(II) acetate, tin(II) octanoate, tin(II) ethylhexanoate, and tin(II) laurate, as well as dialkyltin(IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, and dioctyltin diacetate, and bismuth carboxylates, such as bismuth(III) neodecanoate, bismuth 2-ethylhexanoate, and bismuth octanoate, or mixtures thereof, are also known as polyurethane catalysts. Organometallic compounds may be used in combination with strongly basic amines. Nevertheless, organometallic catalysts are generally unstable in the presence of water, making these catalysts less preferred. Amine catalysts lacking reactive groups tend to increase volatile organic compound emissions, making their application to isocyanates less preferred.

[0027] The incorporable amine catalyst (c1) has at least one, preferably 1 to 8, and particularly preferably 1 to 2, isocyanate-reactive groups, such as primary amine, secondary amine, hydroxyl, amide, or urea groups, preferably primary amine, secondary amine, or hydroxyl groups. Incorporable amine catalysts are primarily used in the production of low-emission polyurethanes, particularly those used in automotive interiors. Such catalysts are known and are described, for example, in EP 1 888 664. These include compounds that, in addition to isocyanate-reactive groups, preferably contain one or more tertiary amino groups. At least one of the tertiary amino groups in the incorporable catalyst preferably has at least two aliphatic hydrocarbon radicals, preferably 1 to 10 carbon atoms per radical, particularly preferably 1 to 6 carbon atoms per radical. It is particularly preferred if the tertiary amino group has two radicals independently selected from methyl and ethyl radicals and additional organic radicals. Examples of incorpo- rable catalysts that can be used are bis(dimethylaminopropyl)urea, bis(N,N-dimethylaminoethoxyethyl)carbamate, dimethylaminopropyl urea, N,N,N-trimethyl-N-hydroxyethyl bis(aminopropyl ether), N,N,N-trimethyl-N-hydroxyethyl bis(aminoethyl ether), diethylethanolamine, bis(N,N-dimethyl-3-aminopropyl)amine, dimethylaminopropylamine, 3-dimethylaminopropyl-N,N-dimethylpropane-1, 3-diamine, dimethyl-2-(2-aminoethoxyethanol), (1,3-bis(dimethylamino)propan-2-ol), N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, bis(dimethylaminopropyl)-2-hydroxyethylamine, N,N,N-trimethyl-N-(3-aminopropyl)bis(aminoethyl ether), 1,4-diazabicyclo[2.2.2]octane-2-methanol, and 3-dimethylaminoisopropyldiisopropanolamine, and mixtures thereof.

[0028] Preferably, the catalyst (c) further comprises an amine catalyst (c2) containing a urea structure. Typical examples of catalysts containing a urea structure are 3-(dimethylamino)propylurea and 1,3-bis(3-(dimethylamino)propyl)urea. In a preferred embodiment, the catalyst (c2) comprises a mixture containing 3-(dimethylamino)propylurea and 1,3-bis(3-(dimethylamino)propyl)urea. In a preferred embodiment, the catalyst (c) comprises 1 to 8, more preferably 2 to 6, and particularly preferably 3 to 5 wt % of the catalyst (c2) based on the total weight of the compounds (b) to (f).

[0029] In a preferred embodiment of the present invention, catalyst (c) contains, in addition to the incorporable amine catalyst (c1) and the urea structure-containing catalyst (c2), less than 1 wt. %, preferably less than 0.1 wt. %, of a non-incorporable amine catalyst, based on the total weight of compound (b) having at least two hydrogen atoms reactive with isocyanate groups. Most preferably, catalyst (c) does not contain any catalysts other than catalysts (c1) and (c2).

[0030] In a particularly preferred embodiment, the content of the catalyst (c) is less than 8% by weight, more preferably 3 to 6% by weight, and particularly preferably 3.5 to 5% by weight, based on the total weight of the compounds (b) to (f), excluding the catalyst (c2) containing a urea structure.

[0031] In the present invention, at least one blowing agent (d) containing water is used. The blowing agent may further contain additional chemical blowing agents and / or physical blowing agents. These blowing agents are described, for example, in "Polyurethane Handbook", Carl Hanser Verlag, 2002. ndThe term "chemical blowing agent" is described in Chapter 3.4.5 of the 1994 edition. The term "chemical blowing agent" refers to compounds that form gaseous products by reaction with isocyanates. Examples of these blowing agents are water and carboxylic acids. The term "physical blowing agent" refers to compounds that are dissolved or emulsified in the starting materials for the polyurethane-making reaction and vaporize under the conditions for polyurethane formation. These include hydrocarbons, halogenated hydrocarbons, halogenated hydroolefins, and other compounds, such as perfluorohexane, chlorofluorocarbons, and ethers, esters, ketones, acetals, and / or perfluorinated alkanes, such as liquid carbon dioxide.

[0032] In a preferred embodiment of the blowing agent according to the present invention, less than 10% by weight of a physical blowing agent is used, based on the total weight of the blowing agent (d), and particularly preferably, water is used exclusively as the blowing agent (d). The amount of blowing agent is 5 to 20 g / dm 3 , preferably 7 to 15 g / dm 3 , particularly preferably 8 to 12 g / dm 3 To achieve these densities, preferably 10 to 30 wt %, more preferably 15 to 26 wt %, and particularly preferably 20 to 25 wt % of blowing agent (d) is used, based on the total weight of compounds (b) to (f).

[0033] According to the present invention, a flame retardant can be added. Examples of suitable flame retardants include brominated esters, brominated ethers (Ixol), and brominated alcohols, such as dibromoneopentyl alcohol, tribromoneopentyl alcohol, and PHT-4-diol, as well as chlorinated phosphates, such as tris(2-chloroethyl)phosphate, tris(1,3-dichloropropyl)phosphate, tricresylphosphate, tris(2,3-dibromopropyl)phosphate, tetrakis(2-chloroethyl)ethylenediphosphate, dimethylmethanephosphonate, diethyldiethanolaminomethylphosphonate, and commercially available halogenated flame-retardant polyols. Other phosphates or phosphonates that can be used include diethylethanephosphonate (DEEP), triethylphosphate (TEP), dimethylpropylphosphonate (DMPP), and diphenylcresylphosphate (DPC) as liquid flame retardants.

[0034] Materials that can be used in addition to the flame retardants mentioned above to provide flame retardancy to rigid polyurethane foams are inorganic or organic flame retardants, such as red phosphorus, preparations containing red phosphorus, aluminum oxide hydrate, antimony trioxide, arsenic oxide, ammonium polyphosphate and calcium sulfate, expandable graphite and cyanuric acid derivatives, such as melamine, and mixtures of at least two flame retardants, such as ammonium polyphosphate and melamine, and optionally corn starch or ammonium polyphosphate, melamine and expandable graphite; aromatic polyesters can also be used for this purpose, optionally.

[0035] Preferred flame retardants are bromine-free. Particularly preferred flame retardants consist of atoms selected from the group consisting of carbon, hydrogen, phosphorus, nitrogen, oxygen and chlorine, especially from the group consisting of carbon, hydrogen, phosphorus and chlorine.

[0036] Preferred flame retardants do not contain groups reactive with isocyanate groups. The flame retardants are preferably liquid at room temperature. DEEP, TEP, DMPP and DPC are particularly preferred.

[0037] Because flame retardants, especially liquid flame retardants, tend to cause emissions of volatile organic compounds, it is extremely important that they are used in an amount of less than 1% by weight, preferably less than 0 to 0.5% by weight, based on the total weight of compounds (b) to (f). More preferably, flame retardant (e) does not contain tris(2-chloropropyl)phosphate (TCPP), and particularly preferably no phosphorus-based flame retardants are used.

[0038] Optionally, further auxiliaries and / or substances (f) can be added to the reaction mixture to produce the polyurethane foams of the present invention. Examples include surface-active substances, foam stabilizers, cell regulators, fillers, light stabilizers, dyes, pigments, hydrolysis stabilizers, and substances with fungistatic and bacteriostatic properties, as well as antioxidants. Such substances are known and are described, for example, in the "Polyurethane Handbook," Hanser Publishers Munich, 2nd edition 1993, chapters 3.4.4 and 3.4.6 to 3.4.11.

[0039] The example of usable surface-active substance is a compound that helps to homogenize starting material, and is also suitable for adjusting the cell structure of plastics.Example of emulsifier can include, for example, sulfated castor oil and sodium salt of fatty acid and salt of fatty acid and amine, such as diethylamine oleate, diethanolamine stearate, diethanolamine ricinoleate, salt of sulfonic acid, such as alkali metal salt or ammonium salt of dodecylbenzene- or dinaphthylmethane disulfonic acid and ricinoleic acid;Example of foam stabilizer can include, for example, siloxane-oxyalkylene copolymer and other organopolysiloxane, ethoxylated alkylphenol, ethoxylated fatty alcohol, paraffin oil, castor oil ester or ricinoleic acid ester, turmeric oil and peanut oil;Example of cell adjuster can include, for example, paraffin, fatty alcohol and dimethylpolysiloxane. Other materials suitable for improving emulsification and cell structure and / or foam stability are the above-mentioned oligomeric acrylates having polyoxyalkylene and fluoroalkane moieties as pendant groups. The amount of surfactant typically used is 0.01 to 10 parts by weight per 100 parts by weight of component (b).

[0040] The foam stabilizers used may include conventional foam stabilizers, such as silicone-based foam stabilizers, examples of which are siloxane-oxyalkylene copolymers and other organopolysiloxanes and / or ethoxylated alkylphenols and / or ethoxylated fatty alcohols.

[0041] The light stabilizers used may include light stabilizers known in polyurethane chemistry, such as phenolic stabilizers, for example 3,5-di-tert-butyl-4-hydroxytoluene and / or Irganox products from BASF, phosphites, for example triphenyl phosphite and / or tris(nonylphenyl) phosphite, UV absorbers, for example 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, branched and and linear, and 2,2'-(2,5-thiophenediyl)bis[5-tert-butylbenzoxazole], as well as stabilizers known as HALS stabilizers (hindered amine light stabilizers), such as bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl)sebacate, n-butyl-(3,5-di-tert-butyl-4-hydroxybenzyl)bis(1,2,2,6-pentamethyl-4-piperidinyl)malonate, and diethyl succinate polymers with 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol.

[0042] Examples of antioxidants are phenolic substances such as 2,6-di-tert-butyl-4-methylphenol, benzenepropanolic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9 branched alkyl esters, amine antioxidants such as N,N'-di-isopropyl-p-phenylenediamine, thiosynergists such as dilauryl 5-thiodipropionate, phosphites and phosphonites such as triphenyl phosphite, diphenyl alkyl phosphites, benzofuranones and indolinones, other antioxidants such as O-, N- and S-benzyl compounds, triazine compounds, amides of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, esters of substituted and unsubstituted benzoic acid, nickel compounds, and esters of β-10-thiodipropionic acid, or mixtures of two or more of these antioxidants. Such antioxidants are described, for example, in WO 2017125291 and are commercially available, for example, under the trade names Irganox 1076, Irganox 245, Irganox 2000, Irganox E201 (vitamin E), Irganox 5057 or Irgafos 38.

[0043] The term "filler," especially reinforcing filler, refers to conventional organic and inorganic fillers, reinforcing agents, extenders, and agents for improving the wear behavior of paints, coating compositions, etc., which are known per se. Specific examples that may be mentioned are inorganic fillers, such as silicate minerals, for example, phyllosilicates, such as antigorite, serpentine, hornblende, amphibole, chrysotile, and talc; metal oxides, such as kaolin, aluminum oxide, titanium oxide, and iron oxide; metal salts, such as chalk, barytes; and inorganic pigments, such as cadmium sulfide and zinc sulfide, and glass. Kaolin (china clay), aluminum silicate, and coprecipitates of barium sulfate and aluminum silicate, as well as natural and synthetic fibrous minerals, such as wollastonite, and metal, especially glass, fibers of various lengths are preferably used, which may be optionally sized. Examples of organic fillers which can be used are carbon, melamine, rosin, cyclopentadienyl resins and graft polymers, as well as cellulose fibers, polyamide fibers, polyacrylonitrile fibers, polyurethane fibers and polyester fibers derived from aromatic and / or aliphatic dicarboxylic acid esters, in particular carbon fibers.

[0044] The inorganic and organic fillers can be used individually or in the form of a mixture, and the amount of these added to the reaction mixture is advantageously 0.5 to 50% by weight, preferably 1 to 40% by weight, based on the weight of components (a) to (f), although the content in mats, nonwovens and woven fabrics made of natural and synthetic fibers can reach up to 80% by weight, based on the weight of components (a) to (f).

[0045] The production of polyurethanes according to the present invention generally involves mixing (a) a polyisocyanate, (b) a polymeric compound having isocyanate-reactive groups, (c) a catalyst, optionally (d) a blowing agent, (e) a chain extender and / or crosslinker, and (f) an auxiliary and / or additive to obtain a reaction mixture, and reacting the reaction mixture to obtain a polyurethane. The expression reaction mixture here means, for the purposes of the present invention, a mixture of an isocyanate-reactive compound (b) and an isocyanate (a) with a working conversion of less than 90% based on the isocyanate groups.

[0046] Here, it is preferred to use a two-component process in which all of the starting materials (a) to (f) are present in either the isocyanate component (A) or the polyol component (B). Here, it is preferred that all substances capable of reacting with isocyanates are added to the polyol component (B), while starting materials that are not reactive with isocyanates can be added to either the isocyanate component (A) or the polyol component (B). It is particularly preferred that the additives added to the isocyanate component (A) are those that do not have functional groups that react with the NCO functional groups of the isocyanates, i.e., that only additives that are inert to isocyanates are used. The isocyanate component (A) and the polyol component (B) are mixed to form a reaction mixture. In a preferred embodiment, an isocyanate component (A) containing a polyisocyanate (a) and a polyol component (B) containing a compound (b) having at least two hydrogen atoms reactive with isocyanate groups, a catalyst (c), and a blowing agent (d) are prepared, and then the isocyanate component (A) and the polyol component (B) are mixed to obtain a reaction mixture. The polyol component and the isocyanate component are preferably reacted in a weight ratio of 90 to 150 parts by weight of the isocyanate component (A) to 100 parts by weight of the polyol component (B), more preferably 100 to 120 parts by weight of the isocyanate component (A) to 100 parts by weight of the polyol component (B), and particularly preferably 110 to 125 parts by weight of the isocyanate component (A) to 100 parts by weight of the polyol component (B).

[0047] Components (a)-(c) and optionally (d)-(f) are reacted in amounts such that the equivalent ratio of NCO groups of polyisocyanate (a) to the sum of reactive hydrogen atoms of components (b), (c), (d), and optionally (e) and (f) is preferably 0.2-1.5:1, more preferably 0.25-0.8:1, and particularly preferably 0.28-0.5:1, where a ratio of 1:1 corresponds to an Isocyanate Index of 100.

[0048] The isocyanate component (A) and the polyol component (B) are storage stable and can typically be stored at room temperature for several months. After storage, it may be necessary to homogenize components (A) and / or (B). In a preferred embodiment, the polyol component (B) has a viscosity at 25°C of 50 to 800 mPas, more preferably 150 to 600 mPas, and particularly preferably 210 to 550 mPas.

[0049] In a preferred embodiment, the reaction is carried out so that the string time is 7 to 15 seconds, more preferably 8 to 12 seconds, and the tack-free time is preferably 10 to 30 seconds, more preferably 11 to 22 seconds, and most preferably 12 to 16 seconds. This allows the reaction mixture to be sprayed onto walls and overhead without dripping. Additionally, the polyol component is non-corrosive.

[0050] The polyurethane foams obtained by the method of the present invention have low density, good mechanical properties, and low emissions of volatile organic compounds, especially 1,2-dichloropropane. In preferred embodiments, volatile organic compound (VOC) emissions according to international standards ISO 16000-3-6-9-11 and EN 16516 are less than 10 milligrams per cubic meter of air three days after foam production and less than 1 milligram per cubic meter of air 28 days after foam production. The method of the present invention allows for spraying on a variety of substrates, including stone, wood, concrete, and textiles. [Example]

[0051] The present invention will now be described with reference to examples.

[0052] The following parameters were determined: Cream Time: Cream time was determined as the time from the start of mixing to the start of the volume expansion of the mixture. Cream time was determined according to Annex E of European Standard EN 14315-1.

[0053] String Time The stringing time, also known as the gel time, was determined as the interval from mixing to the juncture at which a string could be pulled from the reaction mixture. The gel time was determined according to Annex E of European Standard EN 14315-1.

[0054] Tuck Free Time The tack-free time was determined as the interval from mixing to the point when the top surface of the foam was no longer tacky. The tack-free time was determined according to Annex E of European Standard EN 14315-1.

[0055] Overall free foam density Using the procedure for determining core envelope density, the overall free foam density was determined by taking foam samples from the center of the sample with all skins from the base to the surface. These samples were weighed, the volume determined, and these values ​​were used to calculate the density. The overall free foam envelope density was determined in accordance with Annex C of European Standard EN 14315-2.

[0056] The following materials were used to prepare the examples: Polyol 1: Polyetherol starting from a mixture of sucrose and glycerol as starter molecules and propylene oxide with a hydroxyl value of 490 mg KOH / g Polyol 2: Polyetherol started from propylene glycol as starter molecule and ethylene oxide and propylene oxide with a hydroxyl value of 30 mg KOH / g Polyol 3: A polyetherol started with ethylenediamine as the starter molecule and propylene oxide with a hydroxyl value of 470 mg KOH / g Polyol 4: A polyetherol started from diethylene glycol as starter molecule and ethylene oxide with a hydroxyl value of 180 mg KOH / g Polyol 5: Polyetherol started from propylene glycol as starter molecule and propylene oxide with a hydroxyl value of 250 mg KOH / g Cat 1: Tris-(dimethylaminopropyl)amine Cat 2: Pentamethyldiethylenetriamine (PMDETA) Cat 3: Diethyltoluoldiamine (DETDA) Cat 4: 2-[(2-[2-(dimethylamino)ethoxy]ethyl)methylamino]ethanol, Jeffcat® ZF-10 from Huntsman Cat 5: N,N,N'-trimethylaminoethylethanolamine from BASF Cat 6: Mixture of 3-(dimethylamino)propyl urea and 1,3-bis[3-(dimethylamino)propyl]urea (Dabco NE 1070 from Evonik) Surfactant 1: Silicone surfactant, Tegostab B 8870® from Evonik Surfactant 2: Tall oil Flame retardant 1 (FR1): Tris(2-chloropropyl)phosphate (TCPP) Flame retardant 2 (FR2): Triethyl phosphate Isocyanate: Lupranat® M20 S (polymeric methylene diphenyl diisocyanate (PMDI)) with a viscosity of approximately 210 mPa*s at 25°C

[0057] Manufacturing Process The polyol component (B) and the isocyanate component (A) were prepared as disclosed in Table 1. All amounts are given in parts by weight based on the polyol component or isocyanate component, respectively. The components were thoroughly mixed and then foamed by the process described below. The components were foamed by vigorous mixing of the polyol component.

[0058] [Table 1]

[0059] [Table 2]

[0060] Examples 1-4 are comparative examples. 1,2-Dichloropropane (1,2-DCP) and catalyst emissions were determined after 28 days in accordance with international standard ISO 16000-3-6-9-11 by placing foam samples from all examples in a volatile organic compound (VOC) stainless steel ventilated test chamber, taking air samples from the test chamber outlet after the specified storage period, and analyzing these air samples using gas chromatography and mass spectrometry.

[0061] LCI values ​​are health-based reference concentrations of volatile organic compounds for inhalation exposure used to assess 28-day emissions from single products during laboratory test chamber procedures. LCI values ​​should be applied in product safety assessments with the ultimate goal of avoiding health risks from long-term exposure to the general population. They are usually expressed in μg / m 3 It is expressed as:

[0062] Examples 5 and 6 result in 1,2-DCP-free foams with very low density and low emissions of volatile organic compounds below the minimum concentration limit (LCI). Furthermore, the foam from Example 6 emits even less amine-based compounds compared to Example 5. The polyol components from Examples 5 and 6 of the present invention have low viscosity, are easy to process, and are not classified as hazardous materials.

Claims

1. (a) a polyisocyanate containing PMDI; (b) a compound having at least two hydrogen atoms reactive with isocyanate groups, comprising (b1) at least one polyether polyol obtained by alkoxylation of a di- or tri-functional starter molecule having a hydroxyl number of 210 to 400 mg KOH / g, and (b2) at least one polyether polyol obtained by alkoxylation of an aliphatic diamine; (c)(c1) a catalyst comprising at least one incorporable amine catalyst; (d) a blowing agent comprising water; (e) optionally a flame retardant; (f) optionally auxiliary and additional substances; to obtain a reaction mixture, spraying the reaction mixture onto a substrate, and curing the reaction mixture to obtain a polyurethane foam, ３ 1. A method for producing a polyurethane foam having a density of the reaction mixture comprising less than 1 part by weight of a phosphorus-based flame retardant; method.

2. 2. The method according to claim 1, wherein an isocyanate component (A) containing a polyisocyanate (a) and a polyol component (B) containing a compound (b) having at least two hydrogen atoms reactive with an isocyanate group, a catalyst (c), and a blowing agent (d) are prepared, and then the isocyanate component (A) and the polyol component (B) are mixed to obtain the reaction mixture.

3. 3. The method of claim 1 or 2, wherein the catalyst (c) comprises, in addition to the at least one incorporable amine catalyst (c1), at least one catalyst (c2) comprising a urea structure.

4. The method according to any one of claims 1 to 3, wherein the content of the catalyst (c) is less than 8 wt% based on the total weight of the compounds (b) to (f), excluding the catalyst (c2) containing a urea structure.

5. 5. The method of claim 1, wherein the isocyanate and the isocyanate-reactive compound are mixed at an isocyanate index of 25 to 80.

6. 6. The method according to any one of claims 1 to 5, wherein water is used in an amount of 10 to 30% by weight, based on the total weight of compounds (b) to (f).

7. The method according to any one of claims 1 to 6, wherein the compound (b) having at least two hydrogen atoms reactive with isocyanate groups comprises at least one aliphatic or aromatic diamine-based chain extender (b3).

8. 8. The process according to claim 1, wherein the compound (b) having at least two hydrogen atoms reactive towards isocyanate groups comprises at least one polyether polyol (b4) obtained by alkoxylation of a di- or trifunctional starter molecule having a hydroxyl number of 20 to 50 mg KOH / g.

9. 9. The process according to claim 1, wherein the compound (b) having at least two hydrogen atoms reactive towards isocyanate groups comprises at least one polyether polyol (b5) obtained by alkoxylation of a di- or trifunctional starter molecule having a hydroxyl number of from 100 to less than 210 mg KOH / g.

10. The method according to any one of claims 1 to 9, wherein the compound (b) having at least two hydrogen atoms reactive with an isocyanate group comprises 5 to 30 wt% of a polyol (b1), 5 to 30 wt% of a polyol (b2), 0.5 to 5 wt% of an aliphatic or aromatic diamine chain extender (b3), 30 to 60 wt% of a polyol (b4), and 5 to 30 wt% of a polyol (b5), based on the total weight of the compounds (b) each having at least two hydrogen atoms reactive with an isocyanate group.

11. The method of any one of claims 1 to 10, wherein the polyol component (B) has a viscosity of 50 to 800 mPa.s.

12. 12. The method of any one of claims 1 to 11, wherein the string time is from 7 to 15 seconds and the tack-free time is from 10 to 30 seconds.

13. A polyurethane foam obtainable by the method according to any one of claims 1 to 12.

14. Total volatile organic compound (VOC) emissions after 28 days according to the international standard ISO 16000-3-6-9-11 are 1 mg / m ３ The polyurethane foam of claim 13, wherein the tensile strength is less than 1 / 2.

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