Polyurethanes having reduced aldehyde emission

Abstract

The present invention relates to a process for the production of polyurethanes where (a) polyisocyanate, (b) polymeric compounds having groups reactive toward isocyanates, (c) catalysts, (d) a CH-acidic compound of the general formula R.sup.1CH.sub.2R.sup.2, where R.sup.1 and R.sup.2 independently of one another are an electron-withdrawing moiety of the general formula C(O)R.sup.3 or CN, where the moiety R.sup.3 is selected from the group consisting of NH.sub.2, NHR.sup.4NR.sup.5R.sup.6, OR.sup.7 or R.sup.8, where R.sup.4, R.sup.5, R.sup.6, R.sup.7, and R.sup.8 are independently selected from the group consisting of aliphatic, araliphatic or aromatic hydrocarbons, which may have substitution, and optionally (e) blowing agent, (f) chain extender and/or crosslinking agent, and (g) auxiliaries and/or additives are mixed to give a reaction mixture, and the reaction mixture is allowed to complete a reaction to give the polyurethane. The present invention further relates to polyurethanes produced by this process and to the use of these polyurethanes in the interior of means of transport.

Claims

1. A process for producing a polyurethane, the process comprising: mixing (a) a polyisocyanate, (b) polymeric compounds having groups reactive toward isocyanates selected from the group consisting of a polyetherpolyol, a polyesterpolyol and a mixture thereof, (c) catalysts, comprising incorporable amine catalysts, (d) a CH-acidic compound of the general formula
R.sup.1CH.sub.2R.sup.2, where R.sup.1 and R.sup.2 independently of one another are an electron-withdrawing moiety of the general formula C(O)R.sup.3, where the moiety R.sup.3 is selected from the group consisting of NH.sub.2, NHR.sup.4NR.sup.5R.sup.6, OR.sup.7 and R.sup.8, where R.sup.4, R.sup.5, R.sup.6, R.sup.7, and R.sup.8 independently are selected from the group consisting of an aliphatic hydrocarbon, an araliphatic hydrocarbon, and an aromatic hydrocarbon, which optionally have substitution, and optionally (e) a blowing agent, (f) a chain extender and/or a crosslinking agent, and (g) auxiliaries and/or additives to give a reaction mixture, and reacting the reaction mixture to give the polyurethane, wherein the compound R.sup.1CH.sub.2R.sup.2 has a molecular weight greater than 300 g/mol, and wherein a molecular weight on the polymeric compounds b) is from 400 to 15,000 g/mol and a functionality of the polymeric compounds b) is from 2 to 8.

2. The process as claimed in claim 1, wherein the moiety R.sup.3 is NHR.sup.4NR.sup.5R.sup.6, OR.sup.7, or R.sup.8, and the moieties R.sup.4, R.sup.5, R.sup.6, R.sup.7, and R.sup.8 are each independently of one another an aliphatic hydrocarbon having from 1 to 15 carbon atoms, which may optionally be substituted.

3. The process as claimed in claim 1, wherein the groups reactive toward isocyanates are selected from the group consisting of OH, NH and NH.sub.2 groups.

4. The process as claimed in claim 1, wherein the quantity of component (d), based on the total weight of components (a) to (f), is from 0.01 to 5% by weight.

5. The process as claimed in claim 1, wherein the polymeric compounds (b) having groups reactive toward isocyanates comprise polyetherols.

6. The process as claimed in claim 1, wherein the incorporable amine catalysts comprise a group reactive toward isocyanates, and one or more tertiary aliphatic amino groups.

7. The process as claimed in claim 6, wherein at least one tertiary amino group comprises two moieties selected mutually independently from a methyl and an ethyl moiety, and another organic moiety.

8. The process as claimed in claim 1, wherein the polyurethane is a polyurethane foam with an average density of from 20 to 850 g/L.

9. The process as claimed in claim 1, wherein the polyurethane is a compact polyurethane with an average density of more than 850 g/L.

10. The process as claimed in claim 9, wherein the polyurethane is cable-sheathing.

11. A polyurethane, produced by the process as claimed in claim 1.

12. An interior of means of transport, comprising the polyurethane as claimed in claim 11.

13. The process as claimed in claim 1, wherein the CH-acidic compound (d) comprises more than one CH-acidic group.

Description

(1) Starting Materials: Polyol A: Polyetherol with OH number 28 mg KOH/g and functionality 2.7 based on ethylene oxide and propylene oxide, with propylene oxide content 84% by weight and ethylene oxide content 14% by weight Polyol B: Polyetherol with OH number 250 mg KOH/g and functionality 2.0 based on polyol A (35%), propylene oxide (45%), and dimethylaminopropylamine (20%) TEOA: Triethanolamine Isopur SU-12021: Black paste from ISL-Chemie Jeffcat ZF10: Catalyst from Huntsman Jeffcat DPA: Catalyst from Huntsman

(2) Additives A1: dimethyl 1,3-acetonedicarboxylate A2: N-methylacetoacetamide A3: N,N-dimethylacetoactamide A4: 2-cyanoacetoactamide A5: methyl cyanoacetate A6: 2-Cyano-N-(2-hydroxyethyl)acetamide A7: methyl 2-(2-hydroxyethylcarbamoyl)ethanoate A8: reaction product of malonic acid and diethylene glycol (2:3Mw 458) A9: trimethylolpropane triacetoacetate (Mw 386) A6 and A7 were added in the form of a 10% by weight strength aqueous solution to the mixture A. Isocyanate A: Mixture of 85 parts of carbodiimide-modified 4,4-MDI and 15 parts of polymeric diphenylmethane diisocyanate PMDI with NCO content 27.1

(3) The mixture A was produced by mixing the following components: 92.0 parts by weight of polyol A 3.0 parts by weight of polyol B 1.5 parts by weight of TEOA 0.5 parts by weight of Isopur SA-21050 1.9 parts by weight of water 0.4 part by weight of Jeffcat DPA 0.2 part by weight of Jeffcat ZF10 0.5 part by weight of compounds A1 to A7 of table 1

(4) The mixture A and the isocyanate component A, and also the additives of table 1, were mixed with one another with an isocyanate index of 100, and charged to a closed mold to give moldings with an average density of 160 g/L.

(5) Formaldehyde was determined by a procedure based on ASTM D5116-06. The size of the chamber was 4.7 liters. The polyurethane samples used were pieces measuring 110 mm?100 mm?25 mm. When molded foams were tested, parts made of the interior of the foam were used. The temperature of the test chamber during the test was 65? C., and the relative humidity was 50%. The air replacement rate was 3.0 liters per hour. The exhaust air stream with volatile aldehydes from the polyurethane was passed through a cartridge with 2,4-dinitrophenylhydrazine-coated silica during 120 minutes. The DNPH cartridge was then eluted with a mixture of acetonitrile and water. The concentration of formaldehyde of the eluate was determined by means of HPLC. The detection limit for formaldehyde emissions for this setup is ?11 ?g/m.sup.3.

(6) TABLE-US-00001 TABLE 1 formaldehyde values determined in the chamber for semirigid foams without addition of additives (reference), and also with addition of the respective additives A1 to A9 as in the respective concentrations stated in parts by weight, based on the total weight, of the mixture A. Formaldehyde Conc. in A (?g/m.sup.3) Reference 792 A1 0.50% 142 A2 0.50% 109 A3 0.50% 323 A4 0.50% 133 A5 0.50% 130 A6 0.50% 273 A7 0.50% 282 A8 0.50% 342 A9 0.50% 80

(7) TABLE-US-00002 TABLE 2 VOC values (ppm) according to VDA 278 of the resulting semirigid foams on addition of the respective additives A4, A5, A6, A7, and A9. VOC total (ppm) Remark A4 (0.25 p) 76 including 32 ppm of A4 A5 (0.25 p) 133 including 100 ppm of A5 A6 (0.25 p) 40 no A6 or derivatives of A6 detectable A7 (0.25 p) 54 no A7 or derivatives of A7 detectable A9 (0.25 p) 37 no A9 or derivatives of A9 detectable