Polyurethane with reduced aldehyde emissions

Abstract

The present invention relates to a method for producing a polyurethane, comprising the steps of: (a) a polyisocyanate; (b) a polymeric compound having isocyanate-reactive groups; (c) optionally a catalyst; (d) a compound of the general formula W-Kw-NH-C(O)-CH2-Q; and, optionally, (e) a blowing agent; (f) a chain extender and / or a crosslinker; and (g) an auxiliary and / or additive, wherein W- represents a cyclic amine, which may be substituted, and which is bonded to -Kw- via a nitrogen atom, -Kw- represents a linear or branched hydrocarbon group, N represents a nitrogen atom, C represents a carbon atom, O represents an oxygen atom, H represents a hydrogen atom, and -Q represents a cyanide (-CN) or a compound of the general formula -C(O)-R 2 and R 2 -NH2, -NH-R 3 -NR 4 R 5 , -OR 6 or -R 7 (In the formula, -R 3 , -R 4 , -R 5 , -R 6 and -R 7 are independently selected from the group consisting of optionally substituted aliphatic, araliphatic or aromatic hydrocarbons. ) represents a group selected from the group consisting of .} to obtain a reaction mixture, and reacting the countermixture to obtain a polyurethane. The present invention further relates to polyurethanes producible by the process according to the invention, and to a method for using said polyurethanes in an enclosed space.

Description

[Technical Field]

[0001] The present invention relates to a method for producing polyurethanes, comprising: (a) a polyisocyanate; (b) a polymeric compound having isocyanate-reactive groups; (c) optionally a catalyst; (d) a compound of the general formula W-Kw-NH-C(O)-CH2-Q; and optionally, (e) a blowing agent; (f) a chain extender and / or a crosslinker; and (g) an auxiliary and / or additive, wherein W represents a cyclic amine, which may be substituted, and which is bonded to Kw via a nitrogen atom; Kw represents a linear or branched hydrocarbon group; N represents a nitrogen atom; C represents a carbon atom; O represents an oxygen atom; and H represents a hydrogen atom; and Q represents a cyanide (CN) or a compound of the general formula -C(O)-R 2 and R 2 -NH2, -NH-R 3 -NR 4 R 5 , -OR 6 or -R 7 (In the formula, R 3 , R 4 , R 5 , R 6 and R 7 are independently selected from the group consisting of optionally substituted aliphatic, araliphatic, or aromatic hydrocarbons. ) represents a group selected from the group consisting of.} to obtain a reaction mixture, and then reacting the reaction mixture to obtain a polyurethane. The compound (d) used is in particular a compound represented by the general formula W-Kw-NH-C(O)-CH2-C(O)-NH-Kw-W (wherein -Kw- and -W are more preferably each identical). The present invention further relates to polyurethanes producible by the method according to the invention and to the use of such polyurethanes in enclosed spaces, such as vehicles. [Background technology]

[0002] Polyurethanes have many applications, for example in the furniture industry as seat cushions or as binders for particle board, in the construction industry as insulation, for example for pipes, hot water tanks or refrigerators, and also, for example, as trim pieces in automobile manufacturing. Polyurethanes are often used especially in automobile manufacturing, for example in automobile exterior trim, for example as spoilers, roof elements, suspension elements, and in automobile interior trim, for example as headliners, foam carpet backing, door trim, steering wheels, gear knobs and seat cushions.

[0003] Polyurethanes are known to emit organic substances that can cause unpleasant odors or, in high concentrations, ill health. Confined spaces, such as the interior of buildings, and vehicles, such as automobiles, are particularly affected. One example of such emissions is the emission of aldehydes. Various approaches already exist to reduce aldehyde emissions.

[0004] For example, Patent Document 1 describes that aldehyde emissions can be reduced by adding a polymeric substance containing primary and / or secondary amino groups later. The amine groups in the polymer are responsible for reducing emissions. Because they are reactive with isocyanates and are largely inactivated by the reaction with isocyanates, the polymeric active substance must be applied to pre-prepared foams. The disadvantage of this method is the complicated process, which involves post-treatment of the foam. It cannot be used in compact systems or closed-cell foams.

[0005] Patent Document 2 describes the use of polyhydrazodicarbonamide as a substance for reducing aldehyde emissions from polyurethane foams. However, significant aldehyde reduction is achieved only by adding large amounts of polyhydrazodicarbonamide, from 2% to 5.5% by weight, to the polyol component. Because polyhydrazodicarbonamide also has catalytic properties, adding this amount of this substance alters the reaction profile. Furthermore, even when using large amounts of polyhydrazodicarbonamide, the aldehyde reduction achieved needs to be improved.

[0006] Patent Document 3 describes a compound of the general formula R 1 -CH2-R 2 (In the formula, R 1 and R 2 are independently electron-withdrawing groups. The use of C—H-acidic compounds, represented by C—H, in combination with an incorporable catalyst to reduce formaldehyde emissions has been described. Although this can efficiently reduce formaldehyde, the foam samples still exhibit high emissions of volatile organic compounds (VOCs).

[0007] Aminocrotonates that can be used as catalysts in the production of polyurethanes are also known from Patent Document 4. Patent Document 5 describes polyurethane catalysts based on tertiary amines with a pyrrolidine structure. Patent Document 5 further discloses that the catalysts described exhibit low emissions with respect to aldehyde emissions, in particular formaldehyde emissions. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] European Patent No. 1428847 [Patent Document 2] US Patent Application Publication No. 20130203880 [Patent Document 3] International Publication No. 2015082316 [Patent Document 4] European Patent No. 629607 [Patent Document 5] International Publication No. 2016020200 Summary of the Invention [Problem to be solved by the invention]

[0009] It is therefore an object of the present invention to provide polyurethanes, particularly polyurethane foams, which have improved emission characteristics, particularly of aldehydes such as formaldehyde, and also have excellent emission characteristics of further compounds, such as nitrogen-containing emissions and odorous emissions. [Means for solving the problem]

[0010] The object of the present invention is to provide a method for producing a polyisocyanate comprising (a) a polyisocyanate, (b) a polymeric compound having isocyanate-reactive groups, (c) optionally a catalyst, (d) a compound of the general formula W-Kw-NH-C(O)-CH2-Q, and optionally (e) a blowing agent, (f) a chain extender and / or a crosslinker, and (g) an auxiliary and / or additive, wherein W represents a cyclic amine, optionally substituted, linked to -Kw- via a nitrogen atom, Kw represents a linear or branched hydrocarbon group, N represents a nitrogen atom, C represents a carbon atom, O represents an oxygen atom, and H represents a hydrogen atom, and Q represents a cyanide (CN) or a compound of the general formula -C(O)-R 2 and R 2 -NH2, -NH-R 3 -NR 4 R 5 , -OR 6 or -R 7 (In the formula, R 3 , R 4 , R 5 , R 6 and R 7are independently selected from the group consisting of optionally substituted aliphatic, araliphatic, or aromatic hydrocarbons. ) represent a group selected from the group consisting of {} to obtain a reaction mixture, and reacting the reaction mixture to obtain a polyurethane.

[0011] The invention further relates to the use of the polyurethane in confined spaces, such as vehicles.

[0012] For the purposes of the present invention, the term "polyurethane" includes all known polyisocyanate polyaddition products. These include addition products derived from isocyanates and alcohols, and also modified polyurethanes that may contain isocyanurate structures, allophanate structures, urea structures, carbodiimide structures, uretonimine structures, biuret structures, and other isocyanate addition products. These polyurethanes according to the present invention consist, in particular, of solid polyisocyanate polyaddition products, such as duromers, and foams based on polyisocyanate polyaddition products, such as flexible, semi-rigid, rigid, or integral foams, as well as polyurethane coatings and binders. "Polyurethane" is also understood to mean polymer blends of polyurethanes and additional polymers, and also foams composed of these polymer blends. The polyurethanes according to the present invention are preferably polyurethane foams or solid polyurethanes that contain no additional polymers in addition to the polyurethane units (a) to (g) defined herein.

[0013] In the context of the present invention, "polyurethane foam" is understood to mean foams according to DIN 7726. Flexible polyurethane foams according to the present invention have a compressive stress / compressive strength at 10% compression according to DIN 53 421 / DIN EN ISO 604 of 15 kPa or less, preferably 1 to 14 kPa, in particular 4 to 14 kPa. Semi-rigid polyurethane foams according to the present invention have a compressive stress at 10% compression according to DIN 53 421 / DIN EN ISO 604 of 15 kPa or more but less than 80 kPa. According to DIN ISO 4590, semi-rigid and flexible polyurethane foams according to the present invention preferably have an open cell content of 85% or more, particularly preferably 90% or more. Further details regarding flexible and semi-rigid polyurethane foams according to the present invention can be found in "Kunststoffhandbuch", Vol. 7, "Polyurethane", Carl Hanser Verlag, 3rd Edition (1993), Chapter 5.

[0014] The rigid polyurethane foams according to the invention exhibit a compressive stress at 10% compression of at least 80 kPa, preferably at least 120 kPa, particularly preferably at least 150 kPa. Furthermore, the rigid polyurethane foams have a closed cell content according to DIN ISO 4590 of at least 80%, preferably at least 90%. Further details regarding the rigid polyurethane foams according to the invention can be found in "Kunststoffhandbuch", Vol. 7, "Polyurethane", Carl Hanser Verlag, 3rd Edition (1993), Chapter 6.

[0015] In the context of the present invention, "elastomeric polyurethane foam" is understood to mean a polyurethane foam according to DIN 7726 which, after a short-term deformation of 50% of its thickness according to DIN 53 577, does not show a lasting deformation of more than 2% of its starting thickness after 10 minutes. Rigid, semi-rigid or flexible polyurethane foams may be relevant.

[0016] "Integral polyurethane foam" is understood to mean a polyurethane foam according to DIN 7726 which has edge zones that have a higher density than the core as a result of the molding process. The overall apparent density, averaged over the core and edge zones, is preferably 100 g / L or more. In the context of the present invention, integral polyurethane foams may be rigid, semi-rigid or flexible polyurethane foams. Further details regarding integral polyurethane foams according to the present invention can be found in "Kunststoffhandbuch", Vol. 7, "Polyurethane", Carl Hanser Verlag, 3rd Edition (1993), Chapter 7.

[0017] In a preferred embodiment, the polyurethane according to the present invention is a polyurethane foam having an average density of 10 to 850 g / L, preferably a semi-rigid, flexible, or rigid polyurethane foam, particularly preferably an elastomeric flexible, semi-rigid, or integral polyurethane foam. Elastomeric integral polyurethane foams preferably have a density, averaged over the core and edge zones, of 150 g / L to 500 g / L. Flexible polyurethane foams preferably have an average density of 10 to 100 g / L. Semi-rigid polyurethane foams preferably have an average density of 70 to 150 g / L. In the context of the present invention, the average density of a polyurethane foam is understood to mean, for example, the density of the foam averaged over the polyurethane portions, e.g., the cell walls and lamellae of the foam, and the gas contained by the polyurethane foam body.

[0018] In another preferred embodiment, the polyurethane is a solid polyurethane having a density of preferably 850 g / L or more, preferably 900 to 1400 g / L, and particularly preferably 1000 to 1300 g / L. The solid polyurethane is obtained here without the addition of a blowing agent. For the purposes of the present invention, small amounts of blowing agent, such as water present in the polyol as a result of the production process, are not considered to constitute the addition of a blowing agent here. The reaction mixture for the preparation of compact polyurethane preferably contains less than 0.2% by weight, particularly preferably less than 0.1% by weight, and in particular less than 0.05% by weight, of water.

[0019] The polyurethanes according to the invention are preferably used in the interiors of means of transport, such as ships, aircraft, lorries, cars or buses, especially cars or buses, and especially automobiles. The interiors of cars and buses are referred to herein as automobile interior parts. Flexible polyurethane foams can be used as seat cushions, semi-rigid polyurethane foams as door trim elements or back foams of instrument panels, integral polyurethane foams as steering wheels, shift knobs or headrests, and solid polyurethanes can be used, for example, as cable sheaths.

[0020] The polyisocyanate component (a) used in the preparation of polyurethanes according to the present invention includes all polyisocyanates known for the preparation of polyurethanes, including aliphatic, cycloaliphatic, and aromatic di- or polyisocyanates known from the prior art, and any desired mixtures thereof, such as diphenylmethane 2,2'-, 2,4'-, and 4,4'-diisocyanate, mixtures of monomeric diphenylmethane diisocyanate and its homologues with higher ring numbers (polymeric MDI), isophorone diisocyanate (IPDI) and its oligomers, toluylene 2,4- or 2,6-diisocyanate (TDI) and their mixtures, tetramethylene diisocyanate and its oligomers, hexamethylene diisocyanate (HDI) and its oligomers, and naphthylene diisocyanate (NDI) and their mixtures.

[0021] Preferred are 2,4- and / or 2,6-toluylene diisocyanate (TDI) or mixtures thereof, monomeric diphenylmethane diisocyanate and / or higher-nuclear homologues of diphenylmethane diisocyanate (polymeric MDI) and mixtures thereof. Further possible isocyanates are described, for example, in "Kunststoffhandbuch", Vol. 7, "Polyurethane", Carl Hanser Verlag, 3rd Edition (1993), Chapters 3.2 and 3.3.2.

[0022] The polyisocyanate component (a) can be used in the form of a polyisocyanate prepolymer. These polyisocyanate prepolymers can be obtained by reacting an excess amount of the above-mentioned polyisocyanate (component (a-1)) with a polymer compound (b) having an isocyanate-reactive group (component (a-2)) and / or a chain extender (f) (component (a-3)) at a temperature of, for example, 30°C to 100°C, preferably about 80°C, to obtain an isocyanate prepolymer.

[0023] The polymer compound (a-2) having an isocyanate-reactive group and the chain extender (a3) ​​are known to those skilled in the art and are described, for example, in Chapter 3.1 of "Kunststoffhandbuch (Plastics Handbook)", Vol. 7, "Polyurethane", Carl Hanser Verlag, 3rd Edition (1993). Thus, the polymer compound (a-2) having an isocyanate-reactive group may also be the polymer compound (b) having an isocyanate-reactive group described below.

[0024] Usable polymeric compounds (b) having isocyanate-reactive groups include all known compounds having at least two isocyanate-reactive hydrogen atoms, such as those having a functionality of 2 to 8 and a number-average molecular weight of 400 to 15,000 g / mol. Thus, for example, compounds selected from the group consisting of polyether polyols, polyester polyols, and mixtures thereof can be used.

[0025] Polyetherols are produced from epoxides, such as propylene oxide and / or ethylene oxide, or from tetrahydrofuran and hydrogen-activated starter compounds, such as aliphatic alcohols, phenols, amines, carboxylic acids, water, and compounds based on natural substances, such as sucrose, sorbitol, or mannitol, using catalysts, which may contain basic catalysts or double metal cyanide catalysts, as described, for example, in International Patent Application EP 2005 / 010124, EP 90444, or WO 05 / 090440.

[0026] Polyesterols are prepared, for example, from aliphatic or aromatic dicarboxylic acids and polyhydric alcohols, polythioether polyols, polyesteramides, hydroxylated polyacetals and / or hydroxylated aliphatic polycarbonates, preferably in the presence of an esterification catalyst. Further possible polyols are described, for example, in "Kunststoffhandbuch, Vol. 7, Polyurethane", Carl Hanser Verlag, 3rd Edition (1993), Chapter 3.1.

[0027] In addition to the polyetherols and polyesterols described above, filler-containing polyetherols and polyesterols, also known as polymer polyetherols or polymer polyesterols, can also be used. Such compounds preferably contain dispersed particles of thermoplastics composed of olefinic monomers, such as acrylonitrile, styrene, methacrylate, methacrylic acid, and / or acrylamide. Such filler-containing polyols are known and commercially available. Their preparation is described, for example, in German Patent No. 111,394, U.S. Pat. No. 3,304,273, U.S. Pat. No. 3,383,351, U.S. Pat. No. 3,523,093, German Patent No. 1,152,536, German Patent No. 1,152,537, WO 2008 / 055952, and WO 2009 / 128279. As polymeric compound (b) having isocyanate-reactive groups according to the present invention, it is further possible to use at least one polyesterol obtainable by polycondensation of an acid component with an alcohol component, where the acid component is malonic acid and / or a derivative thereof and the alcohol component is an aliphatic dialcohol having 4 to 12 carbon atoms, the preparation of which is described, for example, in WO 2019 / 149583.

[0028] In a particularly preferred embodiment of the present invention, component (b) comprises a polyetherol and, more preferably, is free of polyesterols.

[0029] The catalytic effect of compound (d) represented by the general formula W-Kw-NH-C(O)-CH2-Q allows the use of additional polyurethane catalysts to be reduced. When an additional catalyst (c) is used, all conventional polyurethane catalysts can be used. When used, catalyst (c) preferably comprises an incorporable amine catalyst, and particularly preferably consists of an incorporable amine catalyst. Catalyst (c) does not include any compounds already included in the definition of compound (d) represented by the general formula W-Kw-NH-C(O)-CH2-Q.

[0030] Representative catalysts that can be used for the preparation include, for example, 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, and preferably 1,4-diazabicyclo[2.2.2]octane, and alkanolamine compounds such as Examples of suitable catalysts include triethanolamine, triisopropanolamine, N-methyl- and N-ethyldiethanolamine, and dimethylethanolamine. Also included are organometallic compounds, preferably organotin compounds, such as tin(II) salts of organic carboxylic acids, such as tin(II) acetate, tin(II) octoate, tin(II) ethylhexoate, and tin(II) laurate, and dialkyltin(IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, and dioctyltin diacetate, and also bismuth carboxylates, such as bismuth(III) neodecanoate, bismuth 2-ethylhexanoate, and bismuth octanoate, or mixtures thereof. The organometallic compounds can be used alone or, preferably, in combination with a strongly basic amine. When component (b) is an ester, it is preferred to use an amine catalyst exclusively.

[0031] The incorporable amine catalyst has at least one, preferably 1 to 8, and particularly preferably 1 to 2 isocyanate-reactive groups, such as primary amine groups, secondary amine groups, hydroxyl groups, amide groups, or urea groups, preferably primary amine groups, secondary amine groups, 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. They consist of compounds that, in addition to one or more isocyanate-reactive groups, preferably one or more tertiary amino groups. It is preferred that at least one of the tertiary amino groups of the incorporable catalyst has at least two aliphatic hydrocarbon groups, preferably 1 to 10 carbon atoms per group, more preferably 1 to 6 carbon atoms per group. It is particularly preferred that the tertiary amino group has two independent groups selected from methyl and ethyl groups and additional organic groups. 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, 1-(3-aminopropyl)pyrrolidine, 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 or mixtures thereof.

[0032] If catalysts (c) are used, they may be used, for example, in a concentration of 0.001% to 5% by weight, in particular 0.05% to 2% by weight, as catalyst / catalyst combination, based on the total weight of component (b).

[0033] The compound (d) represented by the formula W-Kw-NH-C(O)-CH2-Q is the following compound: W may be substituted and represents a cyclic amine bonded to -Kw- via a nitrogen atom in the formula. W- preferably represents a pyrrolidine group bonded to -Kw- via a nitrogen atom. The hydrogen atom of the pyrrolidine group may be substituted, but preferably the pyrrolidine group is unsubstituted. -Kw- preferably represents a linear or branched, preferably linear, hydrocarbon group having 1 to 20, particularly preferably 1 to 10, more preferably 2 to 5, and especially 3 carbon atoms. In the formula, N, C, O, and H represent atoms of the chemical elements nitrogen (N), carbon (C), oxygen (O), and hydrogen (H). Q represents cyanide (CN) or a group of the general formula -C(O)-R 2 represents an electron-withdrawing group of the formula 2 -NH2, -NH-R 3 -NR 4 R 5 , OR 6 or R 7 and R is a group selected from the group consisting of 3 , R 4 , R 5 , R 6 and R 7 are independently selected from the group consisting of optionally substituted aliphatic, araliphatic, or aromatic hydrocarbons. 2 -CH3, -OCH3, -C2H5, -OC2H5, -C3H7, -OC3H7, -C l H 2l+1 , -OC l H 2l+1 , -OC l H 2l OH, -O-(C2H4O) m H, -O-(C3H6O) m H, -O-(C4H8O) m H, -NHCH3, -NH-C l H2l+1 , -NH-(C2H4O)mH, -NH-(C3H6O) m H, -NH-C l H 2l -NH2, -NH-C l H 2l -OH, -NH-(C2H4O) m -C2H4NH2, -NH-(C3H6O) m -C3H6NH2, -NH-(C4H8O) m -C4H8NH2, -NH-NH-C l H 2l+1 , -NH-NH-C l H 2l OH, -NH-NH-C l H 2l NH2, -NH-NH-(C2H4O) m H, -NH-NH-(C2H4O) m -C2H4NH2, -NH-NH-(C3H6O) m H, -NH-NH-(C3H6O) m -C3H6NH2, -NH2, where l represents an integer of 1 to 20, preferably 1 to 10, and m represents an integer of 1 to 50, preferably 1 to 25, and particularly preferably -NH-NH2 or -NH-Kw-W, where -Kw- and -W are as defined above, and in this case R 2 is NH-R 3 and R 3 represents a substituted aliphatic hydrocarbon Kw-W. The compound (d) used is in particular a compound represented by the general formula W-Kw-NH-C(O)-CH2-C(O)-NH-Kw-W, where -Kw- and -W are more preferably the same.

[0034] Particularly preferred compounds (d) are: [ka] and, [ka] and in particular the compounds of formula (I):

[0035] Compound (d) is preferably used in an amount of 0.001% to 5% by weight, in particular 0.05% to 2% by weight, based on the weight of component (b).

[0036] When the polyurethane of the present invention is in the form of a polyurethane foam, the reaction mixture of the present invention further comprises a blowing agent (e). Any blowing agent known for the production of polyurethanes can be used. These can consist of chemical and / or physical blowing agents. Such blowing agents are described, for example, in "Kunststoffhandbuch," Vol. 7, "Polyurethanes," Carl Hanser Verlag, 3rd Edition (1993), Chapter 3.4.5. "Chemical blowing agent" is understood to mean a compound that forms a gaseous product upon reaction with an isocyanate. Examples of such blowing agents are water or carboxylic acids. "Physical blowing agent" is understood to mean a compound that is dissolved or emulsified in the input materials for polyurethane production and vaporizes under the conditions of polyurethane formation. Examples include hydrocarbons, halogenated hydrocarbons, and other compounds, such as perfluoroalkanes, e.g., perfluorohexane, chlorofluorohydrocarbons, and ethers, esters, ketones, acetals, and / or liquid carbon dioxide. The blowing agent can be used in any desired amount. The blowing agent is preferably used in an amount such that the resulting polyurethane foam has a density of 10 to 850 g / L, particularly preferably 20 to 800 g / L, and in particular 25 to 500 g / L. It is particularly preferred to use a blowing agent that comprises water.

[0037] Usable chain extenders and crosslinkers (f) include compounds having at least two isocyanate-reactive groups and a molecular weight of 400 g / mol or less, where molecules with two isocyanate-reactive hydrogen atoms are called chain extenders, and molecules with more than two isocyanate-reactive hydrogen atoms are called crosslinkers. However, it is also possible to omit the chain extender or crosslinker. However, the addition of a chain extender, crosslinker, or optionally a mixture thereof, can prove advantageous for modifying mechanical properties, such as hardness.

[0038] If chain extenders and / or crosslinkers are used, they are usually used in an amount of 0.5 to 60% by weight, preferably 1 to 40% by weight, and particularly preferably 1.5 to 20% by weight, in each case based on the total weight of components (b) to (f).

[0039] When a chain extender and / or crosslinker (f) is used, chain extenders and / or crosslinkers well known in the production of polyurethanes can be used. These are preferably low molecular weight compounds having isocyanate-reactive functional groups, such as glycerol, trimethylolpropane, glycols, and diamines. Further possible low molecular weight chain extenders and / or crosslinkers are listed, for example, in "Kunststoffhandbuch", Vol. 7, "Polyurethane", Carl Hanser Verlag, 3rd Edition (1993), Chapters 3.2 and 3.3.2.

[0040] Auxiliaries and / or additives (g) may also be used. All auxiliary and additive substances known for the production of polyurethanes may be used here. Examples include surface-active substances, foam stabilizers, cell conditioners, mold release agents, fillers, dyes, pigments, flame retardants, antioxidants, hydrolysis stabilizers, mildew inhibitors, bacteriostatic agents, etc. Such substances are known and are described, for example, in "Kunststoffhandbuch", Vol. 7, "Polyurethane", Carl Hanser Verlag, 3rd Edition (1993), Chapters 3.4.4 and 3.4.6 to 3.4.11.

[0041] In particular, the combination of compound (d) and an antioxidant leads to a further reduction in the emission of organic substances such as aldehydes. Examples of antioxidants include 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'-diisopropyl-p-phenylenediamine, thiodinazides 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 β10-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.

[0042] In general, the preparation of polyurethanes according to the invention involves reacting polyisocyanate (a), polyol (b), catalyst (c), compound (d), and, if used, blowing agent (e), chain extender (f), and / or crosslinker (g), 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), (f), and (g) is 0.75 to 1.5:1, preferably 0.80 to 1.25:1. When foamed plastics contain, at least in part, isocyanurate groups, a ratio of NCO groups of polyisocyanate (a) to the sum of reactive hydrogen atoms of components (b), (c), (d), and optionally (e), (f), and (g) of 1.5 to 20:1, preferably 1.5 to 8:1, is typically used. A 1:1 ratio corresponds to an isocyanate index of 100.

[0043] The specific starting materials (a) to (g) for producing the polyurethanes of the present invention vary quantitatively and qualitatively to a small extent in each case, depending on whether the polyurethanes of the present invention are thermoplastic polyurethanes, flexible foams, semi-rigid foams, rigid foams, or integral foams. Thus, for example, the production of solid polyurethanes does not use blowing agents, and the production of thermoplastic polyurethanes primarily uses strictly difunctional starting materials. Further, by way of example, the elasticity and hardness of the polyurethanes of the present invention can be varied by varying the functionality and chain length of the high molecular weight compounds having at least two reactive hydrogen atoms. Such variations are known to those skilled in the art.

[0044] Reactants for producing solid polyurethanes are described, for example, in EP 0 989 146 or EP 1 460 094, those for producing flexible foams are described, for example, in International Patent Applications EP 2005 / 010124 and EP 1 529 792, those for producing semi-rigid foams are described, for example, in "Kunststoffhandbuch, Vol. 7, Polyurethane", Carl Hanser Verlag, 3rd Edition (1993), Chapter 5.4, those for producing rigid foams are described, for example, in International Patent Application EP 2005 / 010955, and those for producing integral foams are described, for example, in EP 364 854, U.S. Pat. No. 5,506,275 or EP 897,402. Compound (d) is then added in each case to the reactants described in these documents.

[0045] The present invention provides not only the process of the present invention, but also polyurethanes obtainable by the process of the present invention. The polyurethanes of the present invention are preferably used in enclosed spaces, for example, as insulation in residential construction, such as pipe or refrigerator insulation; in furniture construction, for example, as decorative elements or seat cushions, as mattresses; and in vehicle interiors, for example, automobile interiors, for example, steering wheels, dashboards, door trim, carpet foam backing, acoustic foam, such as headliners, and also headrests or gear knobs. The polyurethanes of the present invention, in particular, have a significantly reduced formaldehyde emission, not only compared to control products without additives, but also compared to prior art additives for aldehyde reactions. Furthermore, the polyurethanes of the present invention emit very low amounts of volatile organic compounds (VOCs) according to VDA 278 and VDA 277. Finally, the polyurethanes of the present invention exhibit excellent aging behavior and heat resistance. [Example]

[0046] The present invention will now be described with reference to examples.

[0047] Preparation of Compound A1 of the Invention: [ka] 12.6 g of dimethyl malonate and 25.1 g of N-(aminopropyl)pyrrolidine were heated in a glass flask at 150° C. for 6 hours. At this temperature, a vacuum was carefully applied and volatile components (starting material (N-(aminopropyl)pyrrolidine reaches a boiling point at 82° C. and 27 mbar) and the resulting methanol) were distilled off at 10 mbar for 1 hour. A clear red liquid was obtained. Complete conversion of the dimethyl malonate was confirmed by NMR spectroscopy. After cooling to room temperature, the product was used without further purification.

[0048] Preparation of comparative substance V1: [ka] 48.49 g of dimethyl malonate and 93.75 g of 3-(dimethylamino)-1-propylamine were heated in a glass flask at 120° C. for 6 hours. At this temperature, a vacuum was carefully applied and the volatile components were distilled off at 12 mbar for 1 hour. A clear orange liquid was obtained. Complete conversion of the dimethyl malonate was confirmed by NMR spectroscopy. After cooling to room temperature, the product was used without further purification.

[0049] The polyurethane material was prepared as follows: Starting materials: Polyol 1: A glycerol-initiated polyether polyol based on ethylene oxide and propylene oxide having an average OH number of 27 mg KOH / g, an average functionality of 2.5, and a propylene oxide content of 78 wt. % based on the total weight of the polyether. Polyol 2: A glycerol-initiated polyether polyol based on ethylene oxide and propylene oxide having an average OH number of 35 mg KOH / g, an average functionality of 2.7, and a propylene oxide content of 85 wt. % based on the total weight of the polyether. Polyol 3: A glycerol-initiated polyether polyol based on ethylene oxide and propylene oxide having an average OH number of 42 mg KOH / g, an average functionality of 2.7, and a propylene oxide content of 25 wt. % based on the total weight of the polyether. Polyol 4: Polyester polyol consisting of adipic acid, 1,4-butanediol, isophthalic acid, and monoethylene glycol, having an average OH number of 55 mg KOH / g. TEOA: Triethanolamine Isopur SU-12021: Black color paste manufactured by ISL-Chemie Emulsifier: Half ester of maleic acid-olefin copolymer Jeffcat® ZF10: Catalyst manufactured by Huntsman Iso1: polymerizable diphenylmethane diisocyanate (PMDI) with an NCO content of 31.5% by weight and an average functionality of 2.7. Iso2: a prepolymer of methylene diphenyl diisocyanate, dipropylene glycol and polyether polyol having an average OH number of 250 mg KOH / g, a functionality of 2, a propylene oxide content of 83% by weight, an NCO content of 23% by weight, and an average functionality of 2, based on the total weight of the polyether. Iso3: A mixture of methylene diphenyl diisocyanate and the corresponding carbodiimide having an NCO content of 29.5% by weight and an average functionality of 2.2.

[0050] The following compounds (d) were used: [ka]

[0051] Mixture A was prepared by mixing the following ingredients: Polyol 1 50.0 parts by mass Polyol 2 34.3 parts by mass Polyol 3 2.0 parts by mass Polyol 4 6.0 parts by mass TEOA 0.5 parts by mass Emulsifier 0.5 parts by mass Isopool SU-12021 0.5 parts by mass Water 2.9 parts by mass Jeffcat (registered trademark) ZF10 0.3 parts by mass 0.5 to 0.8 parts by weight of compound V1, V2, A1 or A2 (in each case equimolar amounts based on the catalytically active tertiary nitrogen)

[0052] The isocyanate component was prepared by mixing the following ingredients: Iso1 30.0 parts by mass Iso2 35.0 parts by mass Iso3 35.0 parts by mass

[0053] Mixture A containing compound V1, V2, A1 or A2 and the isocyanate component were mixed with an isocyanate index of 100, respectively, and added to a closed mold to obtain moldings with an average density of 120 g / L.

[0054] Formaldehyde and acetaldehyde were measured using a procedure similar to ASTM D-5116-06. The chamber size was 4.7 liters. The polyurethane samples used were 110 mm x 100 mm x 25 mm pieces from the interior of the foam. The temperature in the measurement chamber during the measurements was 65°C and the relative humidity was 50%. The air exchange rate was 3.0 liters / hour. The exhaust stream containing volatile aldehydes from the polyurethane was passed through a cartridge containing silica coated with 2,4-dinitrophenylhydrazine for 120 minutes. The DNPH cartridge was then eluted with a mixture of acetonitrile and water. The concentrations of formaldehyde and acetaldehyde in the eluate were measured by HPLC. With this setup, the detection limit for formaldehyde emission was ≤11 μg / m. 3 and the amount of acetaldehyde released is ≦6 μg / m 3 is.

[0055] Table 1: Formaldehyde values ​​measured in the chamber for semi-rigid foams with the addition of each additive V1-V2 and A1-A2 at the indicated concentrations (in each case expressed in parts by weight of the mixture A above).

[0056] [Table 1]

[0057] Table 1 shows that the use of component (d) of the invention in mixture A in each case results in a very significant reduction in formaldehyde emissions compared to comparative compounds V1 and V2.

Claims

1. A method for producing polyurethane, comprising: (a) a polyisocyanate; (b) a polymeric compound having an isocyanate-reactive group; (c) optionally, a catalyst; (d) General formula W-Kw-NH-C(O)-CH ２ a compound represented by -Q, (e) optionally, a blowing agent; (f) optionally a chain extender and / or a cross-linker, and (g) optionally, auxiliaries and / or additives; wherein W- represents an optionally substituted cyclic amine and is bonded to -Kw- via a nitrogen atom; -Kw- represents a linear or branched hydrocarbon group; N represents a nitrogen atom, C represents a carbon atom, O represents an oxygen atom, and H represents a hydrogen atom, and -Q is cyanide (-CN) or a group of the general formula -C(O)-R ２ and R ２ is -NH ２ , -NH-R ３ -NR ４ R ５ , -OR ６ or -R ７ (In the formula, -R ３ , -R ４ , -R ５ , -R ６ and -R ７ are independently selected from the group consisting of optionally substituted aliphatic, araliphatic, or aromatic hydrocarbons.} to obtain a reaction mixture, and reacting the reaction mixture to obtain a polyurethane.

2. 2. The method of claim 1, wherein W represents an optionally substituted pyrrolidine ring.

3. 3. The method according to claim 1, wherein -Kw- represents a linear, unsubstituted hydrocarbon group having 1 to 10 carbon atoms.

4. 4. The method according to any one of claims 1 to 3, wherein Q represents -C(O)-NH-Kw-W, wherein -Kw- and -W are as defined in claim 1.

5. 5. The method according to claim 4, wherein W represents an optionally substituted pyrrolidine ring, Kw- represents a linear unsubstituted hydrocarbon group having 1 to 10 carbon atoms, and W and Kw are each the same.

6. The method of any one of claims 1 to 5, wherein the polymeric compound (b) having isocyanate-reactive groups comprises a polyetherol.

7. The method of any one of claims 1 to 6, wherein the catalyst (c) comprises an incorporable amine catalyst, the incorporable amine catalyst comprising at least one isocyanate-reactive group.

8. 8. The method of claim 7, wherein the incorporable catalyst used is a compound that contains, in addition to isocyanate-reactive groups, one or more aliphatic tertiary amino groups.

9. 9. The method of claim 8, wherein at least one tertiary amino group of the incorporable catalyst has two groups, independent of each other, selected from a methyl group and an ethyl group and also a further organic group.

10. The method according to any one of claims 1 to 9, wherein the polyurethane is a polyurethane foam having an average density of 10 to 850 g / L.

11. The method according to any one of claims 1 to 10, wherein the polyurethane is a compact polyurethane having an average density of more than 850 g / L.

12. A method according to any preceding claim, wherein the polyurethane is part of a mattress or item of furniture.

13. A polyurethane producible by the method of any one of claims 1 to 12.

14. 14. A method for using the polyurethane of claim 13 in an enclosed space.

15. 15. The method of claim 14, wherein the enclosed space is the interior of a vehicle.

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