POLYURETHANES WITH 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) polymer P formed from ethylenically unsaturated monomers and having an average of more than 2 functional groups of the formula ONH.sub.2 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 the production of polyurethanes, the process comprising: mixing (a) polyisocyanate, (b) polymeric compounds having groups reactive toward isocyanates, (c) catalysts, and polymer P formed from ethylenically unsaturated monomers and having an average of more than 2 functional groups of the formula ONH.sub.2. to give a reaction mixture, and allowing the reaction mixture to complete a reaction to give the polyurethane.

2. The process according to claim 1, wherein the polymer P is a homo- or copolymer having an average of more than 2 repeat units M.sub.A derived from a monoethylenically unsaturated monomer A bearing a functional group of the formula ONH.sub.2.

3. The process according to claim 1, wherein the monoethylenically unsaturated monomer A has the formula I: ##STR00003## in which R is hydrogen or methyl, and A is a group of the formula X[O-Alk].sub.n in which X is a chemical bond or is a bivalent radical which is bonded to the carbon atom that bears R and is selected from phenylene, phenylene-CH.sub.2, C(O), CH.sub.2, OC.sub.2-C.sub.12-alkanediyl and C(O)NR.sup.c(C.sub.2-C.sub.10-alkanediyl) where R.sup.c is hydrogen, C.sub.1-C.sub.4-alkyl or -(C.sub.2-C.sub.12-alkanediyl)ONH.sub.2; n is a number from 0 to 20, where n is not 0 when X is C(O) and Alk is C.sub.2-C.sub.4-alkanediyl.

4. The process according to claim 3, wherein R is hydrogen and A is phenylene-CH.sub.2.

5. The process according to claim 1, wherein the polymer P is a copolymer having, aside from the repeat units of the formula M.sub.A, at least one further repeat unit[s] M.sub.B derived from monoethylenically unsaturated monomers B having no functional group of the formula ONR.sup.1R.sup.2.

6. The process according to claim 5, wherein the monomers B comprise monomers B1 selected from the group consisting of monoethylenically unsaturated C.sub.3-C.sub.8-monocarboxylic acids, monoethylenically unsaturated C.sub.3-C.sub.8-monocarboxylic acids, monoethylenically unsaturated sulfonic acids, amides of monoethylenically unsaturated C.sub.3-C.sub.8-monocarboxylic acids, hydroxy-C.sub.2-C.sub.4-alkyl esters of monoethylenically unsaturated C.sub.3-C.sub.8-monocarboxylic acids, poly-C.sub.2-C.sub.4-alkylene oxide esters of monoethylenically unsaturated C.sub.3-C.sub.8-monocarboxylic acids, di-C.sub.1-C.sub.4-alkylamino-C.sub.2-C.sub.4-alkyl esters of monoethylenically unsaturated C.sub.3-C.sub.8-monocarboxylic acids and N-vinyl lactams.

7. The process according to claim 5, wherein the molar ratio of repeat units M.sub.A to repeat units M.sub.B is in the range from 1:100 to 10:1.

8. The process according to claim 6, wherein the molar proportion of the monomers B1, based on the total number of monomers B, is 10 to 100 mol %.

9. The process according to claim 1, wherein the polymer P is in dissolved form in the aqueous composition.

10. The process as claimed in claim 18, wherein the quantity comprised of component (d), based on the total weight of components (a) to (f), is from 0.01 to 2% by weight.

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

12. The process as claimed claim 1, wherein the catalysts (c) comprise incorporable amine catalysts.

13. The process as claimed in claim 12, wherein compounds used as incorporable catalysts have, alongside the group(s) reactive toward isocyanates, at least one tertiary aliphatic amino group[s].

14. 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.

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

16. A polyurethane produced by a process as claimed in claim[s] 1 .

17. The use of polyurethanes as claimed in claim 16 in the interior of means of transport.

18. The process as claimed in claim 1 wherein the mixing step comprises further mixing (e) a blowing agent, (f) at least one of a chain extender and a crosslinking agent, and (g) at least one auxiliary or additive to give the reaction mixture.

Description

[0103] The invention provides not only the process of the invention but also a polyurethane obtainable by a process of the invention. The polyurethanes of the invention are preferably used in enclosed spaces, for example as thermal insulation materials in residential buildings, for example insulation for pipes and refrigerators, in furniture construction, for example as decorative elements or as seat cushioning, and also in automobile interiors, for example as steering wheels, dashboards, door cladding, carpet-backing foam, acoustic foams, for example roof linings, and also headrests or control buttons.

[0104] The invention will be illustrated below with reference to examples.

[0105] Starting materials for the preparation of the polymer P:

[0106] 4-aminoxymethylstyrene: monomer of the formula I in which R1, R2 and R are H and A is 4-phenylene-CH.sub.2, prepared by the method of Wen-Jing Zhou, Mark E. Wilson, Mark J. Kurth, You-Lo Hsieh, John M. Krochta, Charles F. Shoemaker Macromolecules 1997, 30, 7063-7068.

[0107] Preparation of the polymer P:

[0108] Copolymer of sodium methacrylate and 4-am inoxymethylstyrene

[0109] A solution of 6.89 g (0.08 mol) of methacrylic acid in 50 mL of water was neutralized with 6.72 g (0.08 mol) of solid sodium hydrogen carbonate. The following were added successively to the sodium methacrylate solution thus produced: 50 mL of ethanol, 5.97 g (0.04 mol) of 4-aminoxy-methylstyrene and 0.99 g (0.006 mol) of azoisobutyronitrile. The solution was then freed of oxygen by 3 vacuum/argon cycles and then stirred under argon at 75 C. for 16 hours. The slightly viscous solution was then concentrated by evaporation, ultimately at 90 C. and 1 mbar. 15.21 g of the copolymer P were obtained as a pale beige, brittle resin.

[0110] The polymer was purified by dialysis to remove traces of unconverted sodium methacrylate. The GPC analysis of the copolymer showed the following molecular weight averages: Mn=15 340 g/mol and Mw=123 500 g/mol.

[0111] The molecular weight analysis of the polymer P was effected by means of size exclusion chromatography (GPC). Prior to injection, the sample was filtered through Macherey-Nagel PTFE.20/25 (0.2 m) and separated by means of a separating column combination (PI gel pre-column (PI gel 5 m, ID: 7.5 mm, L: 5 cm), PLgel MIXED B (PL gel 10 m, ID: 7,5 mm, L: 30 cm)). Detection was by means of a DRI HP 1100. Calibration was effected with narrow-distribution polystyrene standards from Polymer Laboratories with molecular weights of M=580 to M=6,870,000, and hen/benzene (M=162). The values outside this elution range were ex-trapolated.

[0112] Feedstocks for polyurethane production [0113] 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 [0114] 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%) [0115] TEOA: Triethanolamine [0116] Isopur SU-12021: Black paste from ISL-Chemie [0117] Jeffcat ZF10: Catalyst from Huntsman [0118] Jeffcat DPA: Catalyst from Huntsman [0119] Additives: [0120] V1: 12% aqueous polyvinylamine solution [0121] V2: sodium sulfite [0122] V3: 2-mercaptobenzoxazole [0123] A1: polymer P according to example [0124] Isocyanate: Mixture of 85 parts of carbodiimide-modified 4,4-MDI and 15 parts of polymeric diphenylmethane diisocyanate PMDI with NCO content 27.1 [0125] The mixture A was produced by mixing the following components: [0126] 92.4 parts by weight of polyol A [0127] 3.0 parts by weight of polyol B [0128] 1.5 parts by weight of TEOA [0129] 0.5 parts by weight of Isopur SA-21050 [0130] 1.9 parts by weight of water [0131] 0.4 part by weight of Jeffcat DPA [0132] 0.2 part by weight of Jeffcat ZF10 [0133] Additive V1 to V3, and, respectively, A1 of table 1

[0134] 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.

[0135] Formaldehyde and the acetaldehydes were 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 mm100 mm25 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 and acetaldehyde of the eluate was determined by means of HPLC. The detection limit for formaldehyde emissions for this setup is 11 g/m.sup.3 and in the case of acetaldehyde emissions is 6 g/m.sup.3.

[0136] Table 1: formaldehyde values determined in the chamber for the polyurethane foams obtained without addition of additives (reference), and also with addition of the respective additives A1 or A2 as in the respective concentrations stated in parts by weight based on the total weight of the mixture A.

TABLE-US-00001 TABLE 1 Conc. in mixture A Formaldehyde Acetaldehyde [% by wt.] (g/m.sup.3) (g/m.sup.3) Reference 824 377 V1 0.5% 51 412 V1 1.0% 19 368 V2 0.1% 301 391 V2 0.55 52 454 V3 0.1 278 277 A1 0.1 266 223 A1 0.25 62 162