Novel catalyst for polyurethane manufacturing

Abstract

The present invention relates to a method for producing an aromatic polyisocyanate comprising the steps of: (a) an aromatic polyisocyanate; (b) a polymeric compound having an isocyanate-reactive group; (c) an optional chain extender and / or crosslinker; (d) a catalyst; and (e) 0.1% by mass to 5% by mass of a compound represented by general formula 1, based on the total mass of the components (a) to (f). [Formula 1] The present invention further relates to a process for the preparation of polyurethanes, comprising mixing at least one cyclic urea structure of the formula TIFF2024504265000009.tif1719, (wherein -X- represents a substituted or unsubstituted three-membered group and R represents a group selected from substituted or unsubstituted alkyl or heteroalkyl groups, substituted or unsubstituted aryl groups, or substituted or unsubstituted alkyl-aryl or heteroalkyl-aryl groups, (f) optionally a blowing agent and (g) optionally additives to obtain a reaction mixture, and reacting the reaction mixture to obtain a polyurethane. The present invention further relates to polyurethanes, preferably polyurethane foams, obtainable by such a process, and to the use of such polyurethane foams in the manufacture of cushions, seat pads and mattresses.

Description

[Technical Field]

[0001] The present invention relates to (a) an aromatic polyisocyanate, (b) a polymer compound having an isocyanate reactive group, (c) optionally a chain extender and / or a crosslinking agent, (d) a catalyst, and (e) 0.1% to 5% by mass of General Formula 1 based on the total mass of components (a) to (f). [ka] The present invention relates to a method for producing polyurethane, comprising: (f) mixing with an optional blowing agent and (g) an optional additive to obtain a reaction mixture; and reacting the reaction mixture to obtain polyurethane. The present invention further relates to polyurethane that can be obtained by such a method, preferably polyurethane foam, and to a method for using such polyurethane foam in the manufacture of cushions, seat pads and mattresses. [Background technology]

[0002] Polyurethanes and polyurethane catalysts are known. In the production of polyurethanes, the reaction between isocyanates and polyols is typically carried out in the presence of a catalyst, particularly a strongly basic amine catalyst containing a tertiary nitrogen atom or a metal catalyst. A disadvantage of metal catalysts is that they are not very environmentally friendly because they contain heavy metals. Metal catalysts also tend to undergo hydrolysis in the presence of water, losing their catalytic activity. For this reason, they can only be used to a limited extent in the pre-reaction mixture, such as the so-called polyol component, and therefore many metal compounds are excluded.

[0003] Strongly basic amine catalysts are far more stable, but they have the disadvantage of migrating from the finished polyurethane, resulting in undesirable emissions of volatile organic compounds and odors. Known strongly basic catalysts also often cause further emissions of organic compounds, such as aldehydes. This is undesirable, especially when polyurethane is used in enclosed spaces, such as seat pads, mattresses, or automotive interiors.

[0004] Therefore, incorporateable catalysts containing isocyanate reactive groups that are co-incorporated into the polyurethane structure during polyurethane formation are often used. While this can reduce undesirable catalyst emissions, incorporateable catalysts also catalyze the reverse reaction, resulting in a chain reaction of degradation. Consequently, polyurethanes with incorporateable catalysts often have impaired aging properties. Aldehyde emissions cannot be avoided with incorporateable catalysts either.

[0005] Therefore, catalysts that do not have these drawbacks are needed. One example is lactams. Lactams have the disadvantage of having low activity and requiring very large quantities to be used. However, this negatively affects the mechanical properties of polyurethanes. Therefore, lactams are typically used in combination with strongly basic amine catalysts.

[0006] A further drawback of conventional strong basic amine catalysts is that when these catalysts are used in large quantities in the production of flexible polyurethane foam, especially when the water content exceeds 1% by mass and the isocyanate index is less than 100, aromatic amines, particularly toluenediamine (TDA) and methylenediamine (MDA), become detectable in the concentration range of 10–200 ppm. These are generated particularly on the surface of molded foams. Aromatic amines have been the subject of much domestic and international research for centuries due to their potential carcinogenicity and genotoxicity. Known measures to reduce aromatic amine content include the use of reactive scavenger compounds, such as carboxylic acid anhydrides or aliphatic isocyanates.

[0007] WO2020 / 161010 describes the use of lactams to reduce aromatic amines in such foams. Such harmful aromatic amines occur particularly at isocyanate indices below 100. One possible explanation for this is the fact that, during the formation of polyurethane foam, there are insufficient isocyanate groups available to further react with the MDA formed by the isocyanate-water reaction to obtain urea bonds. The MDA thus formed accumulates, in particular, at the interface with the mold surface, which is relatively cold due to condensation during the production of the molded foam. However, one drawback of the solution described in WO2020 / 161010 is that it involves the use of relatively large amounts of lactams, and the presence of metal catalysts and strongly basic amine catalysts is also essential.

[0008] WO2015050876 describes the use of five-membered polyurea to reduce the aldehyde content in aldehyde-contaminated amine catalysts. WO2016005479 describes the use of cyclic urea having an isocyanate-reactive group as an aldehyde scavenger in the production of polyurethanes. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] WO2020 / 161010 [Patent Document 2] WO2015050876 [Patent Document 3] WO2016005479 [Overview of the project] [Problems that the invention aims to solve]

[0010] Therefore, an object of the present invention is to provide a catalyst for polyurethane reactions that does not exhibit the aforementioned drawbacks of strong basic amine catalysts and metal catalysts, and is more active than known lactams, thereby replacing a significant proportion of the above-mentioned catalysts without adversely affecting the mechanical properties of the resulting polyurethane. This is particularly intended to reduce the emission of organic volatile compounds. A further object of the present invention is to provide a polyurethane catalyst that enables the production of polyurethane foams that result in foams with significantly reduced aromatic amine content, particularly on the surface of molded foams, despite a high water content and a low isocyanate index of less than 95, which are environmentally friendly blowing agents. [Means for solving the problem]

[0011] The object of the present invention is to provide (a) an aromatic polyisocyanate, (b) a polymer compound having an isocyanate reactive group, (c) optionally a chain extender and / or a crosslinking agent, (d) a catalyst, and (e) 0.1% to 5% by mass of General Formula 1 based on the total mass of components (a) to (f). [ka] The object of the present invention is also achieved by a method for producing polyurethane, comprising: (f) mixing with an optional blowing agent and (g) an optional additive to obtain a reaction mixture; and reacting the reaction mixture to obtain polyurethane. The object of the present invention is also achieved by polyurethane, preferably polyurethane foam, that can be obtained by such a method. [Modes for carrying out the invention]

[0012] The term polyurethane in the context of the present invention includes all known foamed polyisocyanate polyaddition products. These include addition products of isocyanates and alcohols, and also modified polyurethanes which may contain isocyanurate, allophanate, urea, carbodiimide, uretonimine or biuret structures, and other isocyanate addition products. These polyurethanes according to the invention include in particular solid polyisocyanate polyaddition products, such as duromers, and foams based on polyisocyanate polyaddition products, such as flexible foams, semi-rigid foams, rigid foams or moulded foams, and also polyurethane coatings and binders. "Polyurethane" is further understood to mean polymer blends comprising polyurethanes and further polymers, and foams made from these polymer blends. The polyurethanes according to the invention are preferably polyurethane foams or solid polyurethanes which do not contain further polymers in addition to the polyurethane units (a) to (g) made clear below.

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

[0014] The rigid polyurethane foam according to the present invention exhibits a compression stress at 10% compression of 80 kPa or more, preferably 120 kPa or more, particularly preferably 150 kPa or more. Further, the rigid polyurethane foam has a closed cell content of more than 80%, preferably more than 90%, according to DIN ISO 4590. Further details regarding the rigid polyurethane foam according to the present invention can be found in "Kunststoffhandbuch", Volume 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 compliant with DIN 7726, which, after undergoing a short-term deformation of 50% of its thickness in accordance with DIN 53 577, does not exhibit a sustained deformation exceeding 2% of its starting thickness after 10 minutes. This may be, for example, a flexible polyurethane foam.

[0016] The polyurethane molded foam is a polyurethane foam according to DIN 7726 and has a skin or edge region with a higher density than the core as a result of the molding process. The overall apparent density, averaged over the core and the edge region, is preferably in the range of 15 - 800 g / L. Molded foams having a density exceeding 100 g / L are typically referred to as integral skin foams. In the context of the present invention, the polyurethane molded foam may be a rigid polyurethane foam, a semi-rigid polyurethane foam or a flexible polyurethane foam. Further details regarding the polyurethane integral skin foam according to the present invention can be found in "Kunststoffhandbuch", Volume 7, "Polyurethane", Carl Hanser Verlag, 3rd Edition, 1993, Chapter 7. The polyurethane according to the present invention is preferably a polyurethane foam, particularly preferably a rigid polyurethane foam, a semi-rigid polyurethane foam or a flexible polyurethane foam, particularly a flexible polyurethane foam, very particularly preferably a molded flexible polyurethane foam.

[0017] The polyurethanes according to the present invention are preferably used in means of transport, such as ships, aircraft, tankers, passenger cars or buses, particularly passenger cars or buses, and especially in the interiors of automobiles. The interiors of passenger cars and buses are hereafter referred to as automobile interior components. For example, flexible polyurethane foam can be used as seat cushions, semi-rigid polyurethane foam as back foam for door trim elements or instrument panels, integral polyurethane foam as steering wheels, shift knobs or headrests, and solid polyurethane as cable sheaths.

[0018] The polyisocyanate component (a) used in the production of polyurethane according to the present invention includes any polyisocyanate known for the production of polyurethane. These include aliphatic, alicyclic, and aromatic divalent or polyvalent isocyanates known from the prior art, and any desired mixtures thereof. Examples include diphenylmethane 2,2'-, 2,4'-, and 4,4'-diisocyanates, mixtures of monomeric diphenylmethane diisocyanates and diphenylmethane diisocyanate homologs having more rings (polymer MDI), isophorone diisocyanate (IPDI) and its oligomers, torylene 2,4- or 2,6-diisocyanate (TDI) and mixtures thereof, tetramethylene diisocyanate and its oligomers, hexamethylene diisocyanate (HDI) and its oligomers, naphthylene diisocyanate (NDI) and mixtures thereof.

[0019] These preferably include toluene diisocyanate isomers (TDI isomers), methylenediphenyl diisocyanate isomers, and their higher polycyclic congeners (referred to as MDI). The aromatic polyisocyanates used are particularly preferably mixtures containing 2,4'-MDI, 4,4'-MDI, and higher polycyclic congeners of MDI. Furthermore, modified isocyanates, such as isocyanates formed by the incorporation of groups derived from isocyanate groups in polyisocyanates, can also be used. Examples of such groups include allophanate groups, carbodiimide groups, uretonimine groups, isocyanurate groups, urea groups, and biuret groups. In preferred embodiments, the proportion of diphenylmethane 2,4'-diisocyanate is preferably 5% to 30% by mass, and the proportion of diphenylmethane 4,4'-diisocyanate is preferably 40% to 80% by mass, where the mass percentages in each case are relative to the total mass of aromatic polyisocyanate (a). In preferred embodiments, the proportion of higher polycyclic congeners of diphenylmethane diisocyanate is 3% to 30% by mass, particularly preferably 5% to 25% by mass.

[0020] Aromatic polyisocyanates may also be used in the form of prepolymers. To do this, the aromatic polyisocyanate (a1) described above is reacted in excess with a compound containing an isocyanate-reactive compound (a2). The compound (a2) used here is preferably a polymer compound having an isocyanate-reactive group as described in (b). When an isocyanate prepolymer is used as the aromatic isocyanate (a), it preferably has an NCO content of 16% to 31% by mass.

[0021] Polymer compounds having isocyanate-reactive group (b) have a number-average molecular weight of at least 450 g / mol, particularly preferably 460 to 12000 g / mol, and have at least two isocyanate-reactive hydrogen atoms per molecule. Preferred polymer compounds having isocyanate-reactive group (b) that can be considered are polyester alcohols and / or polyether alcohols having a functional value of 2 to 8, particularly 2 to 6, preferably 2 to 4, and an average equivalent molecular weight in the range of 400 to 3000 g / mol, preferably 1000 to 2500 g / mol. Polyether alcohols are particularly used.

[0022] Polyether alcohols can be produced by known methods, usually by catalytic addition of alkylene oxides, particularly ethylene oxide and / or propylene oxide, to an H-functional initiator, or by condensation of tetrahydrofuran. When alkylene oxides are added, the term polyalkylene oxide polyol is also used. Usable H-functional initiators are particularly polyfunctional alcohols and / or amines. The use of water, dihydric alcohols, e.g., ethylene glycol, propylene glycol, or butanediol, trihydric alcohols, e.g., glycerol or trimethylolpropane, and higher polyhydric alcohols, e.g., pentaerythritol, sugar alcohols, e.g., sucrose, glucose, or sorbitol is preferred. Preferred amines are aliphatic amines having 10 or fewer carbon atoms, e.g., ethylenediamine, diethylenetriamine, propylenediamine, and amino alcohols, e.g., ethanolamine or diethanolamine. The alkylene oxide used is preferably ethylene oxide and / or propylene oxide, and in the case of polyether alcohols used in the manufacture of flexible polyurethane foams, ethylene oxide blocks are often added to the chain ends. The catalyst used when adding the alkylene oxide is a basic compound, in particular, potassium hydroxide, which is industrially important. If the content of unsaturated components in the polyether alcohol is to be reduced, the catalyst used may be a di- or multi-metallic cyanide compound, a so-called DMC catalyst. Difunctional and / or trifunctional polyalkylene oxide polyols are used in particular in the manufacture of viscoelastic flexible polyurethane foams.

[0023] Furthermore, the compounds having at least two active hydrogen atoms used can be, for example, organic dicarboxylic acids having 2 to 12 carbon atoms, preferably aliphatic dicarboxylic acids having 8 to 12 carbon atoms, and polyester polyols that can be produced from polyhydric alcohols having 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms, preferably diols. Examples of useful dicarboxylic acids include succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, and the isomer naphthalenedicarboxylic acid. The use of adipic acid is preferred. Here, the dicarboxylic acids are used individually or in combination with each other. Instead of free dicarboxylic acids, it is also possible to use corresponding dicarboxylic acid derivatives, such as dicarboxylic acid esters or dicarboxylic acid anhydrides of alcohols having 1 to 4 carbon atoms.

[0024] Examples of di- and polyhydric alcohols, particularly diols, include ethanediol, diethylene glycol, propane-1,2- and -1,3-diol, dipropylene glycol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, decane-1,10-diol, glycerol, and trimethylolpropane. It is preferable to use ethanediol, diethylene glycol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, or a mixture of at least two of the mentioned diols, particularly a mixture of butane-1,4-diol, pentane-1,5-diol, and hexane-1,6-diol. It is also possible to use a polyester polyol formed from a lactone, such as ε-caprolactone, or a hydroxycarboxylic acid, such as ω-hydroxycaproic acid and hydroxybenzoic acid. The use of dipropylene glycol is preferred.

[0025] The chain extender and / or crosslinking agent (c) used is a substance having a molecular weight of less than 400 g / mol, preferably 60 to 350 g / mol, wherein the chain extender has two isocyanate-reactive hydrogen atoms, and the crosslinking agent has at least three isocyanate-reactive hydrogen atoms. These may be used individually or in mixture form. It is preferable to use diols and / or triols having a molecular weight of less than 400, particularly preferably 60 to 300, and especially 60 to 150. Useful examples of starting molecules include aliphatic, alicyclic, and / or aromatic diols, and diols containing aromatic structures having 2 to 14, preferably 2 to 10 carbon atoms, such as ethylene glycol, propane-1,3-diol, decane-1,10-diol, o-, m-, p-dihydroxycyclohexane, diethylene glycol, dipropylene glycol, and preferably butane-1,4-diol, hexane-1,6-diol, and bis(2-hydroxyethyl)hydroquinone, triols, such as 1,2,4-, 1,3,5-trihydroxycyclohexane, glycerol, and trimethylolpropane, and ethylene oxide and / or 1,2-propylene oxide, and low molecular weight hydroxyl group-containing polyalkylene oxides based on the diols and / or triols. The chain extender (c) used is particularly preferably monoethylene glycol, butane-1,4-diol, and / or glycerol.

[0026] When chain extenders, crosslinking agents, or mixtures thereof are used, they are advantageously used in amounts of 0.1% to 20% by mass, preferably 0.5% to 10% by mass, and particularly 0.8% to 5% by mass, relative to the mass of components (b) and (c).

[0027] Suitable catalysts (d) for producing polyurethane foam according to the present invention include all known polyurethane catalysts. These include metal catalysts and / or amine catalysts having a tertiary nitrogen atom. According to the present invention, compound (e) having at least one cyclic urea structure represented by general formula 1 is not considered catalyst (d). Catalyst (d) preferably includes an amine catalyst, and the amine catalyst includes a tertiary nitrogen atom.

[0028] When using an amine catalyst, in the context of the present invention, it is preferable to use a compound having a tertiary nitrogen atom that has a relative reactivity of at least 5% with triethylenediamine. Here, the relative reactivity is confirmed by checking the rate constant of the test compound in a butanol-phenyl isocyanate model system at a concentration of 0.50 mol / liter in acetonitrile solvent at 50°C in each case, and comparing it with that of 1,4-diazabicyclo[2.2.2]octane (triethylenediamine). If the rate constant of the test catalyst is up to 20 times smaller than the rate constant when using 1,4-diazabicyclo[2.2.2]octane under the same conditions, a relative reactivity of at least 5% occurs. For details on the determination of the rate constant, see Schwetlick et. Al. Im J. Chem. Soc Perkin Trans. 2, 1994, pp. 599-608 (rate constant k of 1,4-diazabicyclo[2.2.2]octane under the described conditions). b =2.68dm 6 Mole -2 s -1 It is described in ).

[0029] Amine catalysts are preferably reactive amine catalysts, i.e., those containing isocyanate reactive groups. These have 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, and particularly preferably primary amine groups or hydroxyl groups. Incorporable amine catalysts are primarily used in the production of low-emission polyurethanes, particularly for automotive interiors. Such catalysts are known and are described, for example, in EP1888664. These include compounds having one or more, preferably two, tertiary amino groups in addition to isocyanate reactive groups.

[0030] It is preferable that the tertiary amino group of the incorporateable catalyst has at least two aliphatic hydrocarbon groups, preferably having 1 to 10 carbon atoms per group, and particularly preferably having 1 to 6 carbon atoms per group. It is particularly preferable that the tertiary amino group has two independent groups selected from a methyl group (H3C-) and an ethyl group (H3C-H2C-) and further organic groups. Examples of incorporateable catalysts used in preferred embodiments of the present invention are bisdimethylaminopropylurea, bis(N,N-dimethylaminoethoxyethyl)carbamate, dimethylaminopropylurea, N,N,N-trimethyl-N-hydroxyethylbis(aminopropyl ether), N,N,N-trimethyl-N-hydroxyethylbis(aminoethyl ether), diethylethanolamine, bis(N,N-dimethyl-3-aminopropyl)amine, dimethylaminopropylamine, and 3-dimethylaminopropyl-N,N-dimethylpropane-1,3-diamine The following are selected from the group consisting of dimethyl-2-(2-aminoethoxyethanol), (1,3-bis(dimethylamino)propane-2-ol), N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, bis(dimethylaminopropyl)-2-hydroxyethylamine, N,N,N-trimethyl-N-(3-aminopropyl)bis(aminoethyl ether), 3-dimethylaminoisopropyldiisopropanolamine, N-[2-[2-(dimethylamino)ethoxy]ethyl]-N-methyl-1,3-propanediamine, and mixtures thereof. The use of N-[2-[2-(dimethylamino)ethoxy]ethyl]-N-methyl-1,3-propanediamine is particularly preferred.

[0031] In addition to the incorporateable amine catalysts, further amine catalysts can be used to produce polyurethanes. These are preferably selected from the group consisting of 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, triethylamine, tributylamine, dimethylbenzylamine, N-methyl-, N-ethyl-, 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 mixtures thereof.

[0032] The amine catalyst is preferably used in an amount such that the content of tertiary nitrogen atoms is 0.0001 to 0.003 moles / 100g of foam, preferably 0.0004 to 0.002 moles per 100g of foam, and particularly 0.0005 to 0.001 moles. The amine catalyst preferably includes an amine catalyst that can be exclusively incorporated.

[0033] The metal catalyst used can be any conventional metal catalyst. These include organometallic compounds, preferably organotin compounds, such as tin(II) salts of organic carboxylic acids, such as tin(II) acetate, tin(II) octoate, tin(II) ethylhexanoate, and tin(II) laurate; and dialkyltin(IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, and dioctyltin diacetate, dibutyltin dineodecanoate; and further, bismuth carboxylates, such as bismuth(III) neodecanoate, bismuth 2-ethylhexanoate, and bismuth octanoate, or mixtures thereof. The selected metal catalyst is preferably a metal catalyst that is stable against hydrolysis, such as a tin(IV) compound. In particular, dibutyltin dineodecanoate is used as the metal catalyst.

[0034] The catalyst used and the amount of catalyst are preferably selected such that, taking into account the limitations of the amounts according to the invention of the tertiary nitrogen, the polyurethane reaction mixture has a rise time of preferably 30 to 150 seconds, particularly preferably 40 to 110 seconds, and especially 50 to 105 seconds. The rise time is understood to be the time to reach the maximum height in a beaker test with a mass of 100 g of the polyol component and 50 g of the isocyanate component. The cream time is preferably in the range of 10 to 30 seconds, particularly preferably 12 to 25 seconds, and especially 14 to 22 seconds, and the gel or fiber time is preferably 60 to 180 seconds, particularly preferably 70 to 160 seconds, and especially 75 to 145 seconds. Here, the cream time and the gel time are determined in a beaker test at 25 °C with a mass of 100 g of the polyol component and 50 g of the isocyanate component in accordance with DIN EN14315-1:2013.

[0035] Component (e) according to the invention is used in the form of a cyclic urea structure represented by formula 1

Chemical formula

[0036] In one embodiment, R is an isocyanate-reactive group, preferably a reactive group selected from terminal -OH or NH2 groups. In a particularly preferred embodiment, R is unsubstituted.

[0037] R is very preferably a linear unsubstituted hydrocarbon group selected from methyl, ethyl, propyl, pentyl, and hexyl, and in particular R is a methyl group.

[0038] The cyclic urea structure represented by Formula 1 is well known and has been described many times, for example, in US2013281451. The synthesis may begin, for example, with an N-haloalkyl-3-alkylurea, such as 1-(2-chloroethyl)-3-methylurea. These urea compounds are cyclized in the presence of sodium hydride. This synthesis is also described in US2013281451. Alternatively, the synthesis may begin with urea and a diamine (for example, described in EP976796), or by the reaction of a dialkyl carbonate with a diamine (for example, described in EP2548869).

[0039] When obtaining polyurethane foam as a process product according to the present invention, a blowing agent (f) is used. Available blowing agents (f) include chemically acting blowing agents and / or physically acting compounds. A chemical blowing agent is understood to mean a compound that forms a gaseous product upon reaction with an isocyanate, such as water or formic acid. A physical blowing agent is understood to mean a compound that dissolves or emulsifies in the starting material for polyurethane production and vaporizes under polyurethane formation conditions. These include, for example, hydrocarbons, halogenated hydrocarbons, such as halogenated saturated hydrocarbons, and other compounds, such as perfluoroalkanes, such as perfluorohexane, chlorofluorocarbons, and ethers, esters, ketones and / or acetals, such as (cyclo)aliphatic hydrocarbons having 4 to 8 carbon atoms, or hydrofluorocarbons, such as Solkane. (登録商標) It contains 365 mfc, or gases such as carbon dioxide.

[0040] In preferred embodiments of the present invention, the foaming agent (f) used is (f1) water, and more preferably a mixture of foaming agents containing exclusively water. In particular, when seeking to obtain a flexible polyurethane foam, the foaming agent (f) used is water, preferably water alone.

[0041] The amount of foaming agent is preferably adjusted to obtain the desired density. To produce flexible polyurethane foam, the amount of foaming agent is preferably selected so that the density of the polyurethane foam according to the present invention is in the range of 30 to 70 g / l, preferably 40 to 60 g / l, and particularly 45 to 55 g / l. In particular, water alone is used in an amount of 1% to 6% by mass, preferably 2% to 5% by mass, more preferably 2.5% to 4.5% by mass, and particularly 3.0% to 4.5% by mass, relative to the total mass of components (b) to (f).

[0042] Examples of auxiliary agents and / or additives (g) used include surfactants, foam stabilizers, cell regulators, external and internal mold release agents, fillers, pigments, dyes, flame retardants, antistatic agents, aromatic amine reducing agents, such as lactams, hydrolysis stabilizers, antibacterial agents, and bacteriostatic agents. In particular, the use of lactams, such as ε-caprolactam, together with the cyclic urea of ​​the present invention represented by formula I, reduces aromatic amines in polyurethane.

[0043] Further details of the starting materials used can be found, for example, in the Kunststoffhandbuch [Plastics Handbook], Volume 7, Polyurethane, edited by Guenter Oertel, Carl-Hanser-Verlag, Munich, 3rd edition, 1993, Chapter 5, Polyurethanweichschaumstoffe [Flexible Polyurethane Foam].

[0044] In producing a polyurethane according to the present invention, for example, a particularly preferred flexible polyurethane foam, a polymer compound having an isocyanate reactive group (b), an optionally used chain extender and / or crosslinking agent (c), a catalyst (d), a cyclic urea structure (e), an optionally co-used blowing agent (f), and an optionally used auxiliary agent and / or additive (g) are typically mixed to obtain a so-called polyol component, which is then reacted with a polyisocyanate (a) in this form.

[0045] The equivalent ratio of the total reactive hydrogen atoms of components (b), (d), (e) and optionally (c) and (f) is generally 0.75 to 1.5:1, preferably 0.80 to 1.25:1. When the foamed plastic contains at least partially isocyanurate groups, the ratio of the NCO groups of polyisocyanate (a) to the total reactive hydrogen atoms of components (b), (d), (e) and optionally (c) and (f) is typically 1.5 to 20:1, preferably 1.5 to 8:1. Here, a ratio of 1:1 corresponds to an isocyanate index of 100. When a flexible polyurethane foam is manufactured, the mixing ratio is preferably selected such that the equivalent ratio of the NCO group of polyisocyanate (a) to the total reactive hydrogen atoms of components (b), (e), and (f), and (c) and (d) if present, is preferably 0.5 to 0.95:1, particularly preferably 0.6 to 0.8:1, and especially 0.65 to 0.75:1.

[0046] The polyurethane according to the present invention is preferably manufactured by a one-shot method, for example, using high-pressure or low-pressure techniques. The polyurethane according to the present invention is manufactured on a belt, or preferably in a mold. The molded polyurethane foam can be manufactured in an open or closed mold, for example, a metal mold.

[0047] It is particularly advantageous to proceed using a method called the two-component method, in which, as described above, a polyol component is produced and foamed with polyisocyanate (a). The components are preferably mixed at a temperature in the range of 15 to 120°C, preferably 20 to 80°C, and then introduced into a mold or onto a conveyor belt. The temperature inside the mold is usually in the range of 15 to 120°C, preferably 30 to 80°C.

[0048] The polyurethane thus obtained, for example, the flexible polyurethane foam according to the present invention, similarly forms part of the subject matter of the present invention. The flexible polyurethane foam according to the present invention is preferably open-cell and can be used without processing. It also preferably has a tack-free surface.

[0049] The polyurethane according to the present invention is used in all conventional polyurethane applications. The polyurethane according to the present invention is particularly preferred for use in interiors of buildings or means of transport due to its advantageously low discharge characteristics. The polyurethane foam according to the present invention is preferably used in vehicle structures, for example, as backing for carpets, for padded seating or lounging furniture, mattresses or cushions. Further fields of use include automotive safety components, furniture sectors and resting surfaces, armrests and similar components in automotive manufacturing.

[0050] In particular, in the production of molded polyurethane foam, it has been found that by using the components of Formula 1 in combination with an amine catalyst in an amount such that the tertiary nitrogen atom content is 0.0001 to 0.003 moles / 100g of foam, it is possible to significantly reduce the aromatic amine content, especially on the surface of the molded foam, even at isocyanate indices significantly below 100 and water content significantly above 1% by mass, and preferably reduce it to below the detection limit.

[0051] A further advantage is that, in the case of polyurethane according to the present invention, particularly flexible polyurethane foam, the aldehyde content measured in the fully reacted polyurethane can be significantly reduced, often by more than 50%, compared to conventional catalytic polyurethane without the addition of component (e).

[0052] Finally, the mechanical properties of the polyurethane foam according to the present invention, such as compression residual strain, especially after storage in high temperature and humidity (wet compression residual strain), and breathability, and therefore comfort, are also improved. [Examples]

[0053] The present invention will be explained below with reference to the following examples: Preparation of 1-methyltetrahydropyrimidine-2(1H)-one (cyclic urea structure 1 represented by formula 1, where n is equal to 3 and R is a methyl group): Dimethyl carbonate (865 g, 9.6 mol, 1.5 equivalent) was added dropwise over 7 hours at 55°C to a stirred solution of N-methylpropane-1,3-diamine (800 g, 9.1 mol, 1.0 equivalent) and NaOMe (40.2 g, 744 mmol, 5% by mass). The mixture was stirred under reflux for a further 7 hours, then cooled and filtered. After removing volatile substances, the crude product with a purity >95% (1020 g, 8.9 mmol, 98%) was further purified by fractional distillation under reduced pressure using a Vigreux column to obtain the desired target substance with a purity exceeding 99% (935 g, 8.2 mol, 90%; a colorless oil that crystallizes into a colorless solid at room temperature).

[0054] The resulting product had the following properties: Boiling point: 108℃ / 16mbar Melting point: 92°C.

[0055] Preparation of 1-aminopropyltetrahydropyrimidine-2(1H)-one (cyclic urea structure 2 according to formula 1, where n is equal to 3 and R is a 1-aminopropyl group): The preparation was carried out in the same manner as for cyclic urea structure 1, but instead of 9.1 moles of N-methylpropane-1,3-diamine, 9.1 moles (1194 g) of 3,3'-diaminodipropylamine were used.

[0056] Polyol 1: Glycerol-initiated polyoxypropylene - polyoxyethylene, with a polyoxyethylene content of 13% by mass relative to the alkylene oxide content, a hydroxyl value of 28 mg KOH / g, and mainly having primary hydroxyl groups. A polymer polyol based on styrene and acrylonitrile in a polyol ratio of 2:2:1, with a solid content of 44% by mass and a hydroxyl value of 20 mg KOH / g. Polyol 3: Glycerol-initiated polyoxypropylene has a polyoxyethylene content of 74% by mass relative to the alkylene oxide content, and a hydroxyl value of 42 mg KOH / g. Polyol 4: Glycerol-initiated polyoxypropylene - contains 13% by mass of polyoxyethylene relative to the alkylene oxide content, has a hydroxyl value of 35 mg KOH / g, and approximately 85% primary hydroxyl groups. A polymer polyol / graft polyol having a styrene / acrylonitrile copolymer in a polyol ratio of 5:2:1 (m:m), an OH value of 20, and a solids content of 45% by mass. Polyol 6: Glycerol-initiated polyoxypropylene, with a hydroxyl value of 42 mg KOH / g and exclusively having secondary OH groups. Catalyst 1: A 33% by mass solution of triethylenediamine in dipropylene glycol. Catalyst 2: N-[2-[2-(dimethylamino)ethoxyl]-N-methyl-1,3-propanediamine, incorporateable, tertiary amine catalyst from Evonik, available under trade name Dabco® NE300. Catalyst 3: N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine, trade name Jeffcat from Huntsman. (登録商標) Available through DPA. Catalyst 4: 3-(dimethylamino)propylamine-initiated polyoxypropylene, with a polyoxypropylene content of 77% by mass and a hydroxyl value of 250 mg KOH / g. Catalyst 5: 10% by mass of dimethyltin dineodecanoate solution in polyol 1, trade name Fomrez (登録商標) Momentive's PU catalyst, available under UL28. Catalyst 6: 3-dimethylaminopropylamine (DMAPA) Isocyanate 1: A mixture of MDI and a higher polycyclic congener of MDI, with a viscosity of 210 mPas at 25°C and an NCO content of 31.5% by mass. The mixture consists of 2 parts by mass of isocyanate 4,4'-MDI, 48.6 parts by mass of 2,4'-MDI, and 2.4 parts by mass of 2,2'-MDI, with an NCO content of 33.5% by mass. A monomer 4,4'-MDI having an isocyanate content of 3:33.5% by mass of NCO. Stabilizer 1: Low-emission silicone stabilizer from Evonik, available under the trade name Tegostab B8715LF2. Stabilizer 2: Low-emission silicone stabilizer from Evonik, available under the trade name Tegostab B8716LF2.

[0057] Starting with the starting materials reported in Table 1, test panels with dimensions of 18.5 × 19.5 × 3.8 cm were manufactured in a closed mold at a mold temperature of 50°C. For this purpose, polyol components were prepared using the compositions reported in the table, mixed with specific isocyanate components at a specific isocyanate index in a high-pressure mixing head at 35°C, and the resulting mixture was introduced into a mold heated to 60°C. The reported amounts of input materials refer to parts by mass. MDA concentration is reported in ppm. The molded articles were removed from the mold after 5 minutes. The density was approximately 50 g / dm³. 3 That was the case.

[0058] [Table 1]

[0059] [Table 2]

[0060] Comparative Example 1 corresponds to a foam produced using a conventional catalyst. A fast reaction time was achieved, but high levels of aromatic amines were generated, and aldehyde emissions were also high. When the amine catalyst (cat3) was replaced with cyclic urea structure 1, a similar reaction profile was obtained, but the aldehyde emissions from the foam were significantly reduced (Example 1). The aromatic amine content was also significantly reduced. Further reduction of the amine catalyst content resulted in a further reduction of the aromatic amine content (Example 2). Example 3 demonstrates that this effect was achieved with a similar cyclic urea.

[0061] Comparative experiments 2 and 3 showed that even when a large amount of ε-caprolactam was used instead of cyclic urea, foam was obtained only when a metal catalyst was additionally used (Cat 5), and otherwise the foam collapsed. In contrast, the use of a small amount of cyclic urea 1 (0.3 parts instead of 1.5 parts) made it possible to obtain foam without the use of a metal catalyst (Example 4). Finally, when the cyclic urea of ​​the present invention was additionally used with ε-caprolactam (Examples 5 and 6 compared to Comparative Example 4), the reaction time was significantly faster, coupled with a decrease in the aromatic amine content.

[0062] Aromatic amines: The aromatic amine concentration in molded parts made of flexible polyurethane foam was determined based on the ISOPA III test method: the MDA detection method, ISOPA III ref. 11399, "Robust method for the determination of the diaminodiphenylmethane content of flexible polyurethane foams." For this purpose, test specimens were milled after manufacturing and immediately packaged in aluminum foil and plastic bags. The time from demolding to packaging was 30 minutes.

[0063] The surface of the molded foam was cut into panels with a thickness of 0.5 cm. From these panels, 3 cm x 3 cm test pieces were cut out and stacked to form a 3 x 3 x 3 cm cube, which was then measured. This cube of soft foam was placed in a beaker containing 10 ml of 1% acetic acid (reported in mass%). The cube was squeezed 20 times using a ram (approximately 4 cm in diameter), and the solution was transferred to a 50 ml flask. Next, the compression process was repeated twice with 10 ml of 1% acetic acid each time, and this acetic acid was also transferred to the flask after the compression process. After combining the obtained extracts, the mixture was diluted to 50 ml with 1% acetic acid. This solution was filtered through a 0.45 μm filter and prepared for HPLC analysis. Double-checking was performed in all cases. MDA content is reported in ppm.

[0064] Emissions value: The foam test specimens from Comparative Example 8 and Example 9 were analyzed using the chamber method followed by HPLC. Formaldehyde was measured using a procedure similar to ASTM D-5116-06. The chamber size was 4.7 liters. The polyurethane test specimen used was a foam measuring 110 mm × 100 mm × 25 mm from the core. The temperature inside the measurement chamber during measurement was 65°C and the relative humidity was 50%. The air exchange rate was 3.0 liters per hour. The exhaust flow 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 concentration of formaldehyde in the eluate was measured by HPLC. Under this setting, the detection limit for formaldehyde emissions was ≤11 μg / m³. 3 That was the case.

[0065] Table 2 compares the use of the cyclic urea structure 1 of the present invention with the use of a similar five-membered cyclic urea structure (1-methyl-2-imidazolidone) that is not part of the present invention.

[0066] [Table 3]

[0067] The six-membered cyclic urea structure according to the present invention exhibits higher catalytic activity compared to similar five-membered cyclic urea structures not according to the present invention. Therefore, even with smaller amounts used, the start time, gel time, and rise time were shortened. The use of the six-membered cyclic urea structure according to the present invention reduced volatile organic compounds (VOCs) due to VDA277. The aromatic amine content was also slightly reduced in the examples of the present invention.

Claims

1. A method for manufacturing polyurethane, (a) Aromatic polyisocyanates, (b) Polymer compounds having isocyanate-reactive groups, (c) Optional chain extenders and / or crosslinking agents, (d) a catalyst; (e) 0.1% to 5% by mass of the total mass of components (a) to (f) of General Formula 1 【Chemistry 1】 At least one compound represented by a cyclic urea structure of the formula (wherein -X- represents -(CH2)3-, and R represents a substituted or unsubstituted alkyl group), (f) A foaming agent, and (g) A method comprising: optionally mixing with an additive to obtain a reaction mixture; and reacting the reaction mixture to obtain a polyurethane.

2. The method according to claim 1, wherein the water content relative to components (b) to (f) is 1% to 6% by mass.

3. The method according to claim 1 or 2, comprising reacting components (a) to (e), and (f) and (g) if present, to obtain a polyurethane with an isocyanate index of 50 to 95.

4. The method according to any one of claims 1 to 3, wherein there is no further foaming agent in addition to water (f1).

5. The method according to any one of claims 1 to 4, wherein the catalyst comprises an amine catalyst in addition to the compound represented by formula 1, the amine catalyst has tertiary nitrogen atoms, and the amount of tertiary nitrogen atoms in the amine catalyst is 0.0001 to 0.003 moles / 100 g of foam with respect to the mass of the starting components (a) to (f).

6. The tertiary nitrogen atom of the tertiary amino group of the amine catalyst is a methyl group (H ３ The method according to claim 5, comprising two mutually independent groups selected from C- and an ethyl group (H3C-H2C-), and a further organic group.

7. The amine catalyst is bisdimethylaminopropylurea, bis(N,N-dimethylaminoethoxyethyl)carbamate, dimethylaminopropylurea, N,N,N-trimethyl-N-hydroxyethylbis(aminopropyl ether), N,N,N-trimethyl-N-hydroxyethylbis(aminoethyl ether), diethylethanolamine, bis(N,N-dimethyl-3-aminopropyl)amine, dimethylaminopropylamine, 3-dimethylaminopropyl-N,N-dimethylpropane-1,3-diamine, dimethyl-2-(2-aminoethoxy The method according to claim 5 or 6, selected from the group consisting of ethanol, and (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), 3-dimethylaminoisopropyldiisopropanolamine, N-[2-[2-(dimethylamino)ethoxy]ethyl]-N-methyl-1,3-propanediamine and mixtures thereof.

8. The method according to any one of claims 5 to 7, wherein the catalyst comprises a metal catalyst in addition to an amine catalyst, and the metal catalyst is preferably a tin (IV) catalyst.

9. The method according to any one of claims 1 to 8, wherein the aromatic polyisocyanate includes isomers and homologues of diphenylmethane diisocyanate.

10. The method according to any one of claims 1 to 9, wherein the production of the reaction mixture involves mixing an isocyanate component (A) containing an aromatic polyisocyanate (a) with a polyol component (B) containing a mixture of a polymer compound having an isocyanate reactive group (b), a catalyst (d), and a blowing agent (e) containing water.

11. The method according to any one of claims 1 to 10, wherein the reaction of the reaction mixture for obtaining a flexible polyurethane foam is carried out in a mold.

12. Polyurethane obtained by the method described in any one of claims 1 to 11.

13. A method of using the polyurethane foam according to claim 12 for manufacturing cushions, seat pads and mattresses.

Images