DE10027566A1 - Use of isocyanates containing allophanate-, biuret- and/or uretedione structures for the production of polyisocyanate-polyaddition products and polyurethane foams with reduced aromatic amine content - Google Patents

Abstract

Use of isocyanates (I) containing allophanate-, biuret- and/or uretedione structures for the production of polyisocyanate-polyaddition products for the reduction of the aromatic amine content in polyisocyanate-polyaddition products. An Independent claim is also included for the use of the isocyanates (I) for the production of polyurethane foams (II).

Description

The invention relates to the use of modified isocyanates containing allophanate, biuret and / or uretdione structures in the production of polyisocyanate polyaddition products, preferably flexible polyurethane foams, particularly preferably flexible polyurethane foams with a density of 10 to 300 kg / m ³ , in particular mattresses and / or upholstery for furniture or carpets to reduce the content of aromatic amines in the polyisocyanate polyaddition products.

The manufacture of polyisocyanate polyadducts by Implementation of polyisocyanates with reactive towards isocyanates Compounds optionally in the presence of catalysts which the reaction of the isocyanate-reactive substances with iso Accelerate cyanates, blowing agents and / or auxiliaries well known.

The appearance of aromatic amines in polyisocyanate polyadditions products, for example polyurethanes (PUR) is made by one Influenced a number of parameters. Particularly low indices lead to measurable levels even without aging of the polyurethane on aromatic amines, such as toluenediamine (TDA) or diamino diphenylmethane (MDA), in polyurethanes. Such low indices become especially soft and / or viscoelastic Foam qualities used against bed sores or Sore spots, e.g. B. can be used as wheelchair pads. Further lead high temperatures especially in combination with high Air humidity to split the urethane and / or urea bonds. Such conditions are special for some Areas of application of flexible PUR foams are important. On Examples of such special applications are e.g. B. Hospital mattresses that are subjected to steam sterilization. Another example are upholstery materials used in Household can be cleaned with steam cleaners.

The object of the invention was to add polyisocyanate polyadducts products, preferably flexible polyurethane foams, in particular Mattresses or upholstery for furniture and / or carpets wrap after their manufacture or storage as well as at their Use the lowest possible free amine content, ins have special free aromatic amines.  

This task could be achieved through the use described above of isocyanates containing allophanate, biuret and / or uret dione structures in the manufacture of polyisocyanate poly addition products can be solved.

These isocyanates according to the invention contain both free and also isocyanate groups bound by an addition reaction in Form of the allophanate, biuret and / or uretdione shown structures. About free isocyanate groups is in the making the polyisocyanate polyadducts are linked to the Polymer matrix possible while the bound isocyanate groups under suitable conditions, e.g. B. exposure to heat be set and then with aromatic in the polyurethane Amines can react. This formation of free isocyanate groups from previously bound isocyanate groups can already during the exothermic polyaddition reaction to form polyurethanes take place so that aromatic amines formed as a result of the reaction can be connected, or in the event of thermal stress on the Polyurethane material, so for, at this load through Degradation of the aromatic amines formed from the polyurethane matrix, equally generated isocyanate groups as reactants become. Also a direct reaction of aromatic amines with the functionalized isocyanates is possible. Through the modes The isocyanates are compounds with high molecular weight get weight that have a low vapor pressure, so that they, even if during polyisocyanate polyadditions reaction not fully incorporated into the polyurethane matrix should not be evaporated from the polyurethane or migrate. Further advantages of the additives according to the invention are that they are generally simple and homogeneous in the isocyanate components must be incorporated without phase separation result, and the mechanical properties of the resulting Hardly influence the polyurethane material. Also a prepolymer sation z. B. with polyhydroxy or polyamino compounds and subsequent use in the polyol component is possible.

The modification of aliphatic and cycloaliphatic poly isocyanates using urethane, allophanate, uretdione, urea or biuret groups is general, for example in EP-A 183976 described. EP 915110, BP 915111 and EP 915117 describe the Use of allophanate-modified MDI in soft polyurethane foams. EP 911354 describes the use of biuretized Isocyanate or isocyanurate is presented as an isocyanate component. A reduction in the aromatic amine content in poly urethanes is not mentioned in any of these writings.  

Modified isocyanates, preferably diisocyanates are used, the at least one Have allophanate, biuret and / or uretdione structure.

Modified isocyanates of this type are from the specialist literature generally known, commercially available and according to known Process can be produced.

The following figures are examples of education of allophanate, uretdione and biuret structures from isocyanates and the reaction of these structures with amines.

Fig. 1

Presentation of allophanate and reaction with amines

Fig. 2

Representation of biuret and reaction with amines

Fig. 3

Representation of uretdione and reaction with amines

Modified aliphatic, cycloaliphatic are preferred and / or aromatic diisocyanates used. For example can contain the following isocyanates containing allophanate, biuret and / or uretdione structures are used: alkylene diiso cyanates with 4 to 12 carbon atoms in the alkylene radical, such as 1,12-dodecane diisocyanate, 2-ethyl-tetramethylene-diisocyanate-1,4, 2-methylpentamethylene diisocyanate-1,5, tetramethylene diiso 1,4-cyanate and preferably 1,6-hexamethylene diisocyanate; cyclo aliphatic diisocyanates such as cyclohexane-1,3- and -1,4-diiso cyanate and any mixtures of these isomers, 1-isocyanato 3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diiso  cyanate), 2,4- and 2,6-hexahydrotoluylene diisocyanate and the corresponding mixtures of isomers, 4,4'-, 2,2'- and 2,4'-dicyclo hexylmethane diisocyanate and the corresponding isomers mixtures, aromatic di- and polyisocyanates, such as. B. 2,4- and 2,6-tolylene diisocyanate (TDI) and the corresponding isomers mixtures, 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanate (MDI) and the corresponding mixtures of isomers, naphthalene-1,5-diiso cyanate (NDI), mixtures of 4,4'- and 2,4'-diphenylmethane diiso cyanates, mixtures of NDI and 4,4'- and / or 2,4'-diphenyl methane diisocyanates, 3,3'-dimethyl-4,4'-diisocyanatodiphenyl (TODI), mixtures of TODI and 4,4'- and / or 2,4'-diphenyl methane diisocyanates, polyphenylpolymethylene polyisocyanates, Mixtures of 4,4'-, 2,4'- and 2,2'-diphenylmethane diiso cyanates and polyphenylpolymethylene polyisocyanates (raw MDI) and mixtures of crude MDI and tolylene diisocyanates. Before the allophanates, biurets and uretdiones of 4,4'-, 2,4'- and / or 2,2'-diphenylmethane diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate, NDI, phenyl isocyanate, hexamethylene diisocyanate and / or isophorone diisocyanate.

The modified isocyanates according to the invention are in the generally known processes for the preparation of the polyisocyanate Polyaddition products used to increase the content of aromatic Reduce amines in the polyisocyanate polyadducts.

The manufacture of polyisocyanate polyadducts by Implementation of isocyanates with reactive towards isocyanates Compounds optionally in the presence of catalysts, which the reaction of the isocyanate-reactive substances with Accelerate isocyanates, blowing agents and / or auxiliaries is well known. As polyisocyanate polyaddition products can be compact or cellular, for example microcellular, soft, semi-hard or hard polyurethane foam fabrics, thermoplastic polyurethanes, or polyurethane elastomers by conventional methods using the invention Isocyanates are produced. It is preferred to represent them posed isocyanates in the production of flexible foam substances by reacting isocyanates with isocyanates reactive compounds in the presence of catalysts, blowing agents means and, if necessary, aids.

In the production of the polyisocyanate polyaddition products the modified isocyanates are preferred in an amount from 0.2 to 50 wt .-%, based on the total weight of the Production of the polyisocyanate polyadducts used Isocyanates used.  

The common starting materials for the production of Polyisocyanate polyaddition products are exemplified below described.

As isocyanates, in addition to the above modified isocyanates the known aliphatic, cycloaliphatic, araliphatic and preferably aromatic organic isocyanates, preferably polyfunctional ones, especially preferably diisocyanates can be used.

Examples include: alkylene diisocyanates with 4 to 12 carbon atoms in the alkylene radical, such as 1,12-dodecane diisocyanate, 2-ethyl-tetramethylene-diisocyanate-1,4, 2-methyl pentamethylene diisocyanate 1,5, tetramethylene diisocyanate 1,4 and preferably 1,6-hexamethylene diisocyanate; cycloaliphatic Diisocyanates such as cyclohexane-1,3- and -1,4-diisocyanate and be any mixtures of these isomers, 1-isocyanato-3,3,5-trimethyl 5-isocyanatomethyl-cyclohexane (isophorone diisocyanate), 2,4- and 2,6-hexahydrotoluylene diisocyanate and the corresponding iso mer mixtures, 4,4'-, 2,2'- and 2,4'-dicyclohexylmethane diiso cyanate and the corresponding isomer mixtures, aromatic di- and polyisocyanates, such as. B. 2,4- and 2,6-tolylene diisocyanate (TDI) and the corresponding isomer mixtures, 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanate (MDI) and the corresponding iso mer mixtures, naphthalene-1,5-diisocyanate (NDI), mixtures of 4,4'- and 2,4'-diphenylmethane diisocyanates, mixtures of NDI and 4,4'- and / or 2,4'-diphenylmethane diisocyanates, 3,3'-di methyl-4,4'-diisocyanatodiphenyl (TODI), mixtures of TODI and 4,4'- and / or 2,4'-diphenylmethane diisocyanates, polyphenyl polymethylene polyisocyanates, mixtures of 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates (raw MDI) and mixtures of raw MDI and Tolylene diisocyanates. The organic di- and polyisocyanates can be used individually or in the form of their mixtures.

These additional isocyanates can optionally be ester, urine substance, carbodiimide, isocyanurate and / or urethane groups point. For example, the following can be considered: urethane group-containing organic, preferably aromatic polyiso cyanates with NCO contents of 33.6 to 15% by weight, preferably of 31 to 21 wt .-%, based on the total weight, modified 4,4'-diphenylmethane diisocyanate, modified 4,4'- and 2,4'-diphenylmethane diisocyanate mixtures, modified NDI, modified TODI, modified raw MDI and / or 2,4- or 2,6-tolylene diisocyanate. The isocyanates can also be in the form of prepolymers are used, d. H. after partial Reaction with compounds reactive towards isocyanates,  as usually used in polyurethane production become.

As isocyanate-reactive compounds with more common wise at least two reactive hydrogen atoms, usually Hydroxyl and / or amino groups can expediently be such with a functionality of 2 to 8, preferably 2 to 6, and a molecular weight of usually 60 to 10,000, be used. Have proven themselves. B. polyether polyamines and / or preferably polyols selected from the group of poly ether polyols, polyester polyols, polythioether polyols, poly ester amides, hydroxyl-containing polyacetals and hydroxyl group-containing aliphatic polycarbonates or mixtures at least two of the polyols mentioned. Preferably application find polyester-polyols and / or polyether-polyols according to known methods can be produced.

The polyester polyols preferably have a functionality from 2 to 4, in particular 2 to 3, and a molecular weight from usually 500 to 3000, preferably 1200 to 3000 and especially 1800 to 2500.

The polyether polyols have a functionality of preference example 2 to 6 and usually molecular weights of 500 up to 8000.

For example, polymer are also suitable as polyether polyols modified polyether polyols, preferably graft polyether polyols, especially those based on styrene and / or acrylonitrile base by in situ polymerization of acrylonitrile, styrene or preferably mixtures of styrene and acrylonitrile can be put.

The polyether polyols can just like the polyester polyols used individually or in the form of mixtures. Further you can use the graft polyether polyols or polyester polyols and hydroxyl-containing polyester amides, poly acetals and / or polycarbonates are mixed.

The polyol components used for rigid polyurethane foam substances that may have isocyanurate structures can, highly functional polyols, especially polyether polyols based on highly functional alcohols, sugar alcohols and / or Saccharides as starter molecules, for flexible foams 2- and / or 3-functional polyether and / or polyester polyols based Glycerin and / or trimethylolpropane and / or glycols as Starter molecules or alcohols to be esterified. The  Production of the polyether polyols takes place after a be knew technology. Suitable alkylene oxides for the preparation of the Examples of polyols are tetrahydrofuran, 1,3-propylene oxide, 1,2- or 2,3-butylene oxide, styrene oxide and preferably ethylene oxide and 1,2-propylene oxide. The alkylene oxides can be individually can be used alternately in succession or as mixtures. Alkylene oxides are preferably used which are primary Lead hydroxyl groups in the polyol. Be particularly preferred as polyols used to complete the alkoxylation were alkoxylated with ethylene oxide and thus primary hydroxyl have groups. For the production of thermoplastic poly Urethanes are preferably polyols with a functional from 2 to 2.2 and no crosslinking agents.

As isocyanate-reactive compounds can further chain extenders and / or crosslinking agents be applied. For example to modify the mechanical Properties of the Polyiso made with these substances cyanate polyadducts, e.g. B. the hardness, the Addition of chain extenders, crosslinking agents or if appropriate, mixtures thereof also prove to be advantageous. As chain extenders and / or crosslinking agents Water, diols and / or triols with molecular weights from 60 to <500, preferably from 60 to 300 can be used. In consideration come for example aliphatic, cycloaliphatic and / or araliphatic diols with 2 to 14, preferably 4 to 10 carbons atoms of matter, such as B. ethylene glycol, 1,3-propanediol, decane diol-1,10, o-, m-, p-dihydroxycyclohexane, diethylene glycol, di propylene glycol and preferably 1,4-butanediol, 1,6-hexanediol and Bis (2-hydroxyethyl) hydroquinone, triols such as 1,2,4-, 1,3,5-tri hydroxy-cyclohexane, glycerin and trimethylolpropane and lower molecular hydroxyl group-based polyalkylene oxides Ethylene and / or 1,2-propylene oxide and diols and / or triols as starter molecules and nitrogen-containing compounds, such as Diamines, amino alcohols or e.g. B. diethanolamine and / or tri ethanolamine.

Provided for the production of the polyisocyanate polyaddition products Chain extenders, crosslinking agents or mixtures of which are used, they are conveniently used in one Amount from 0 to 20% by weight, preferably from 0.5 to 8% by weight, based on the weight of the reactive towards the isocyanates Compounds used, with thermoplastic polyurethanes are preferably produced without crosslinking agents.  

If appropriate, generally customary Ver bonds are used, for example organic amines, for example triethylamine, triethylene diamine, tributylamine, Dimethylbenzylamine, N, N, N ', N'-tetramethylethylene diamine, N, N, N ', N'-tetramethyl-butanediamine, N, N, N', N'-tetramethyl hexane-1,6-diamine, dimethylcyclohexylamine, pentamethyl dipropylene triamine, pentamethyldiethylenetriamine, 3-methyl-6-dimethylamino 3-azapentol, dimethylaminopropylamine, 1,3-bisdimethylaminobutane, Bis (2-dimethylaminoethyl) ether, N-ethylmorpholine, N-methyl morpholine, N-cyclohexylmorpholine, 2-dimethylaminoethoxyethanol, Dimethylethanolamine, tetramethylhexamethylene diamine, dimethyl amino-N-methylethanolamine, N-methylimidazole, N- (3-aminopropyl) - imidazole, N- (3-aminopropyl) -2-methylimidazole, 1- (2-hydroxyethyl) - imidazole, N-formyl-N, N'-dimethylbutylene diamine, N-dimethylamino ethylmorpholine, 3,3'-bis-dimethylamino-di-n-propylamine and / or 2,2'-dipiparazine diisopropyl ether, dimethylpiparazine, N, N'- Bis (3-aminopropyl) ethylenediamine and / or tris- (N, N-dimethyl aminopropyl) -s-hexahydrotriazine, or containing mixtures at least two of the amines mentioned, including higher molecular weight tertiary amines, as for example be in DE-A 28 12 256 are written, are possible. Furthermore, as Kataly organic metal compounds customary for this purpose are used, preferably organic tin compounds, such as Tin (II) salts of organic carboxylic acids, e.g. B. Tin (II) - acetate, tin (II) octoate, tin (II) ethylhexoate and tin (II) - laurate and the dialkyltin (IV) salts of organic carbon acids, e.g. B. dibutyl tin diacetate, dibutyl tin dilaurate, dibutyl tin maleate and dioctyltin diacetate, but also Zn, Co, Bi- or Fe compounds, e.g. B. Zn stearate. Preferably tertiary aliphatic and / or cycloaliphatic amines in the mixtures be included, particularly preferably triethylenediamine.

As blowing agents, optionally, preferably for the preparation foamed polyurethanes, well-known blowing agents, such as B. substances that have a boiling point under normal pressure in Have a range from -40 ° C to 120 ° C, gases and / or solid propellants medium and / or water are used in usual amounts, for example carbon dioxide, alkanes and or cycloalkanes such as for example isobutane, propane, n- or iso-butane, n-pentane and Cyclopentane, ethers such as diethyl ether, methyl iso butyl ether and dimethyl ether, nitrogen, oxygen, helium, Argon, nitrous oxide, halogenated hydrocarbons and / or part halogenated hydrocarbons such as trifluor methane, monochlorotrifluoroethane, difluoroethane, pentafluoroethane, Tetrafluoroethane or mixtures containing at least two of the contain playfully named blowing agents. Preferred drive medium is water.  

Surfactants are an example of an aid Substances, foam stabilizers, cell regulators, fillers, Dyes, pigments, flame retardants, hydrolysis protection agents, called fungistatic and bacteriostatic substances.

The organic polyisocyanates and compounds with one molecular reactive towards isocyanates weight of 60 to 10000 g / mol in such quantities for implementation brought that the equivalence ratio of NCO groups of the poly isocyanates to the sum of the reactive hydrogen atoms opposite Isocyanate-reactive compounds 0.5 to 5: 1, preferably 0.5 to 3: 1 and in particular 0.5 to 2: 1.

It may be of advantage that the polyurethanes contain at least partially bound isocyanurate groups. In In these cases, a ratio of NCO groups of the Polyiso cyanates to the sum of the reactive hydrogen atoms from 1.5 to 60: 1, preferably 1.5 to 8: 1 are preferably chosen.

The polyisocyanate polyadducts can, for example according to the one-shot process or the well-known prepolymer Processes are produced, for example with the help of the high Pressure or low pressure technology in open or closed Molding tools, reaction extruders or belt systems.

Foams are preferred with the mixtures according to the invention Polyisocyanate polyadducts, for example foamed Polyurethane and / or polyisocyanurates produced.

It has proven to be advantageous to use the polyisocyanate poly addition products according to the two-component process and the compounds reactive towards isocyanates and optionally the catalysts, blowing agents and / or auxiliary and / or additives in the A component and as B component the isocyanates and catalysts and / or blowing agent use funds.

The invention is illustrated by the following examples become.

Examples

An index of 60 was used to obtain foams with measurable aromatic amine contents. The aromatic amines were extracted using a method developed by Prof. Skarping, University of Lund. For this, foam cubes with the dimensions 3 × 3 × 3 cm ^{3 are} expressed 10 times in 10 ml acetic acid (w = 1% by weight). The acetic acid was transferred to a 50 ml volumetric flask with the foam sample compressed. The process is repeated twice and the volumetric flask is then filled up to the measuring mark with acetic acid (w = 1% by weight). The MDA content of the combined extracts was then determined by means of capillary electrophoresis with UV detection (device type: Biofocus 3000, measurement of the peak areas and comparison with imidazole as internal standard). The MDA contents given in the examples correspond to the absolute contents of the MDA formed in the PUR foam.

example 1

Production of a flexible polyurethane foam by mixing 750 g of polyol component with 240 g of isocyanate component (index 60) and transferring the foaming mixture into an aluminum mold (40 cm × 40 cm × 10 cm) heated to 53 ° C., the components being built up as follows :
Polyol component:
97 parts by weight of Lupranol® 2090, molecular weight: 6000, OH number: 28 (Elastogran GmbH)
3 parts by weight of Lupranol® 2047, molecular weight: 4000, OH number: 42 (Elastogran GmbH)
3.31 parts by weight of water
0.8 parts by weight of aminopropylimidazole (BASF Aktiengesellschaft)
0.6 part by weight of 2- (2-dimethylaminoethoxy) ethanol
0.5 part by weight of Tegostab® B 8631 (Goldschmidt)
Isocyanate component:
Mixture of 42 parts Lupranat® M 20 W (Polymer-MDI, Elastogran GmbH) and a mixture of 2,4'- and 4,4'-MDI (11 parts Lupranat® ME and 47 parts Lupranat® MI, Elastogran GmbH).

The resulting foam contained 11 ppm 2,4'-MDA. 4,4'-MDA was undetectable.

Example 2

Production of a flexible polyurethane foam in analogy to Example 1 (index = 60) with the difference that the isocyanate component additionally 2 parts by weight of Basonat® P LR 8926 (Allo phanate-modified HDI, allophanate content approx. 20%, BASF shares society) were admitted.  

The resulting foam contained only 7 ppm 2,4'-MDA. 4,4'-MDA was undetectable.

According to the invention, the MDA content of the foam could be determined by Allo supplement can be significantly reduced.

Example 3

Production of a flexible polyurethane foam in analogy to Example 1 (index = 60) with the difference that the isocyanate additional 5 parts by weight of Basonat® P LR 8926 (Allo phanate-modified HDI, allophanate content approx. 20%, BASF shares society) were admitted.

There was neither 2,4'-MDA nor 4,4'-MDA in the resulting foam to prove.

According to the invention, the MDA content of the foam could be determined by the to 5 parts by weight increased allophanate addition to below night limit of 1 ppm.

Example 4

Production of a flexible polyurethane foam in analogy to Example 1 (index = 60) with the difference that the isocyanate component additionally 2 parts by weight of Basonat HB 100 (biuret modified HDI, BASF Aktiengesellschaft) were added.

The resulting foam contained only 1 ppm 2,4'-MDA. 4,4'-MDA was undetectable.

According to the invention, the MDA content of the foam could be: Biuretz addition can be significantly reduced.

Example 5

Production of a flexible polyurethane foam in analogy to Example 1 (index = 60) with the difference that the isocyanate component additionally 2 parts by weight of Luxate® HD 100 (uretdione modified HDI) were added.

The resulting foam contained only 4 ppm 2,4'-MDA. 4,4'-MDA was undetectable.

According to the invention, the MDA content of the foam could be: Uretdione addition can be significantly reduced.  

Example 6

Production of a flexible polyurethane foam in analogy to Example 1 (index = 60) with the difference that the isocyanate additional 5 parts by weight of Luxate® HD 100 (uretdione modified HDI) were added.

There was neither 2,4'-MDA nor 4,4'-MDA in the resulting foam detectable.

According to the invention, the MDA content of the foam could be determined by the to 5 parts increased uretdione addition to below the detection limit be reduced.

Claims (5)

1. Use of isocyanates containing allophanate, biuret and / or uretdione structures in the manufacture of polyiso cyanate polyaddition products to reduce the content of aromatic amines in the polyisocyanate polyadditions products. 2. Use of aliphatic, cycloaliphatic and / or aromatic diisocyanates according to claim 1. 3. Use according to claim 1 in the manufacture of poly urethane foams. 4. Use according to claim 1 in the production of flexible poly urethane foams with a density of 15 to 300 kg / m ³ . 5. Use according to claim 1 in the manufacture of mattresses and / or upholstery for furniture or carpets.