FLEXIBLE POLYURETHANE FOAMS HAVING IMPROVED LONG-TERM PERFORMANCE CHARACTERISTICS

Abstract

The present invention relates to polyol mixtures comprising (b1) at least one polyether polyol having a hydroxyl value of 10 to 60 mg KOH/g and having a high proportion of ethylene oxide, (b2) at least one polyether polyol having a hydroxyl value of 10 to 100 mg KOH/g, a low proportion of ethylene oxide, and not less than 40% primary OH groups, and (b3) at least one polyether polyol having a hydroxyl value of 10 to 100 mg KOH/g, a low proportion of ethylene oxide, and not more than 30% primary OH groups, and b5) from 0.25 to 10 further parts by weight of polyurea, based on 100 parts by weight of components b1) to b3), optionally present as a constituent of a dispersion polyol based on one or more of components b1) to b3).

The invention further relates to a process for producing flexible polyurethane foams using the mixtures according to the invention, to the thereby obtainable flexible polyurethane foams, and to the use of the thereby obtainable flexible polyurethane foams as a cushioning element for furniture or as a seat element.

Claims

1.-18. (canceled)

19. A mixture b comprising the following components: b1) 75 to 94% by weight of at least one polyether polyol having a hydroxyl value of 10 to 60 mg KOH/g, an OH functionality of at least 2, and ethylene oxide in a proportion of 50 to 100% by weight based on the content of alkylene oxide, b2) b2) 3 to 20% by weight of at least one polyether polyol having a hydroxyl value of 10 to 100 mg KOH/g, an OH functionality of at least 2, ethylene oxide in a proportion of 2 to 30% by weight based on the content of alkylene oxide, and a proportion of primary OH groups of 40 to 100% based on the total number of OH groups in component b2), b3) 3 to 20% by weight of at least one polyether polyol having a hydroxyl value of 10 to 100 mg KOH/g, an OH functionality of at least 2, ethylene oxide in a proportion of 0 to 30% by weight based on the content of alkylene oxide, and a proportion of primary OH groups of 0 to 30% based on the total number of OH groups in component b3), in each case based on the total amount by weight of components b1) to b3), which comes to 100% by weight, and b5) from 0.25 to 10 further parts by weight of polyurea, based on 100 parts by weight of components b1) to b3), and also b4) from 0 to 10 further parts by weight, based on 100 parts by weight of components b1) to b3), of at least one further polyether polyol that differs from components b1) to b3), and b6) from 0 to 15 further parts by weight of filler, based on 100 parts by weight of components b1) to b3).

20. The mixture according to claim 19, wherein the proportion of primary OH groups in component b2) based on the total number of OH groups in component b2) is from 50 to 100%.

21. The mixture according to claim 19, wherein the proportion of primary OH groups in component b3) based on the total number of OH groups in component b3) is from 0 to 25%.

22. The mixture according to claim 19, wherein component b2) has an OH functionality of at least 2.4.

23. The mixture according to claim 19, wherein component b3) has an OH functionality of 2.4 to 3.

24. The mixture according to claim 19, wherein component b1) has an OH functionality of at least 2.4.

25. The mixture according to claim 19, wherein component b1) has a proportion of primary OH groups of 40 to 100% based on the total number of OH groups in component b1).

26. The mixture according to claim 19, wherein component b5) is a polyurea dispersion having a solids content of 10 to 45% by weight based on the total mass of the dispersion based on component b2).

27. The mixture according to claim 19 comprising from 80 to 92% by weight of component b1), from 3.5 to 16% by weight of component b2), from 3.5 to 15% by weight of component b3), and from 0.5 to 6 parts by weight of component b5) polyurea as a constituent of a dispersion polyol based on one or more of components b1) to b3), based on 100 parts by weight of components b1) to b3).

28. A process for producing flexible polyurethane foams in which the following components are mixed to form a reaction mixture and converted into the flexible polyurethane foam: a) at least one polyisocyanate based on diphenylmethane diisocyanate, wherein component a) comprises from 60 to 100% by weight of 4,4′-diphenylmethane diisocyanate based on the total weight of component a), b) a mixture b according to claim 19, c) at least one catalyst, and d) at least one blowing agent comprising water.

29. The process according to claim 28, wherein the components further comprise chain extenders and/or crosslinkers.

30. The process according to claim 28, wherein the components further comprise one or more additives.

31. The process according to claim 28, wherein component a) comprises from 65 to 90% by weight of 4,4′-diphenylmethane diisocyanate, from 0 to 20% by weight of 2,4′-diphenylmethane diisocyanate, and from 10 to 30% by weight of multiring diphenylmethane diisocyanate, in each case based on the total weight of component a).

32. The process according to claim 28, wherein component a) comprises from 68 to 90% by weight, of 4,4′-diphenylmethane diisocyanate, from 0 to 20% by weight, of 2,4′-diphenylmethane diisocyanate, and from 10 to 30% by weight, of multiring diphenylmethane diisocyanate, in each case based on the total weight of component a).

33. The process according to claim 28, wherein water is used as sole blowing agent e).

34. The process according to claim 28, wherein the foam density according to DIN EN ISO 3386 of the polyurethane foam is from 40 to 60 kg/m.sup.3.

35. The process according to claim 28, wherein the compression hardness at 40% according to DIN EN ISO 3386 is from 4.5 to 10 kPa.

36. The process according to claim 28, wherein the rebound resilience of the flexible polyurethane foam according to DIN EN ISO 8307 is at least 35%.

37. A flexible polyurethane foam obtainable by a process according to claim 28.

38. A cushioning element for furniture or a seat element comprising the flexible polyurethane foam according to claim 37.

Description

EXAMPLES

[0144] The constituents listed in Table 3 were foamed to a flexible polyurethane foam using water as blowing agent.

[0145] For this purpose, a polyol component was produced by mixing the specified polyether polyols, catalysts, and additives. The polyol component was mixed with the specified polyisocyanates at the specified index and the mixture was introduced into a closable metal mold (14.5 L), where it cured to form the flexible foam in the closed mold. The metal mold has a temperature of 50° C. and the demolding time was 5 minutes.

[0146] The properties of the resulting flexible polyurethane foams are given in Table 4 below.

[0147] Starting materials used: [0148] Polyol A: OH value 42 mg KOH/g, polyether polyol based on propylene oxide and ethylene oxide (72% by weight) having 77% primary OH groups, starter glycerol. The mean functionality is 2.7. [0149] Polyol B: OH value 35 mg KOH/g, polyether polyol based on propylene oxide and ethylene oxide (13% by weight) having 72% primary OH groups, starter glycerol. The mean functionality is 2.7. [0150] Polyol C: OH value 48 mg KOH/g, polyether polyol based on propylene oxide and ethylene oxide (10% by weight) having fewer than 5% primary OH groups, starter glycerol, ethylene glycol. The mean functionality is 2.5. [0151] Polyol D: OH value 20 mg KOH/g, graft polyol having a 45% content of solids (styrene-acrylonitrile) in 55% polyol C as carrier polyol. The mean functionality is 2.7. [0152] Polyol E: OH value 28 mg KOH/g, polyurea dispersion in polyol having a 20% content of solids in 80% reactive polyether polyol as carrier polyol. The reactive polyether polyol corresponds to b2). [0153] DABCO® 33 LV—Gel catalyst in dipropylene glycol (Air Products) [0154] DABCO® NE 300—Blowing catalyst (Air Products) [0155] Tegostab® BF 2370—Silicone stabilizer (Evonik) [0156] Isocyanate A: is a polymeric MDI and comprises 37.5% 4,4′-MDI and 4.3% 2,4′-MDI, NCO content 31.5% by weight, mixture of two-ring and multiring MDI having a functionality of 2.7 [0157] Isocyanate B: NCO content 33.5% by weight, 4,4′-MDI (˜99%) [0158] Isocyanate C: NCO content 33.5% by weight, 4,4′-MDI (˜50%) and 2,4′-MDI (˜50%) isomer mixture

TABLE-US-00001 TABLE 1 Standards used for foam tests Property Unit Standard Foam density kg/m.sup.3 DIN EN ISO 3386 Compression hardness kPa DIN EN ISO 3386 40% Hysteresis % DIN EN ISO 3386 Tensile strength kPa DIN EN ISO 1 798 Elongation at break % DIN EN ISO 1 798 Rebound resilience % DIN EN ISO 8307 FT.sup.1—Loss of hardness % DIN EN ISO 3385 .sup.1FT—Fatigue test Loss of hardness according to wet compression set

[0159] The test specimens in the upward direction having the dimensions 50 mm×50 mm×25 mm (W×L×H) are placed between two pressure plates and pressed together by means of a clamping device to the height that had resulted in a corresponding pressure load of 8 kPa in the reference hardness measurement (DIN EN ISO 3386). Test specimens are then stored in the climatic test chamber at 37° C. and 80% relative air humidity for 16 h. After 24 hours without clamping device in normal climatic conditions, the compression hardnesses of the test specimens is measured in accordance with DIN EN ISO 3386. The relative loss of hardness is calculated as a percentage.

TABLE-US-00002 TABLE 2 Composition of component A used (isocyanates A, B, and C) in parts by weight. This was used to calculate the composition of component a) in % by weight. The missing amount to 100% by weight is in each case 2,2′-MDI. Worked example isocyanate 1: 4,4′-MDI 71.9% by weight = 0.375*31.3 + 0.986*53.5 + 0.49*15.2, isocyanate 2: 4,4′-MDI 54.8% by weight = 0.375*37.5 + 0.986*20.4 + 0.49*42.1 4,4′ 2,4′ MDI MDI Multiring [% by [% by MDI [% by Iso A Iso B Iso C weight] weight] weight] Isocyanate 1 31.3 53.5 15.2 71.9 9.5 18.2 Isocyanate 2 37.5 20.4 42.1 54.8 22.4 21.8

TABLE-US-00003 TABLE 3 Amounts used of the freely—foamed flexible polyurethane foams (total weight of the components used: isocyanate, polyols, and additives approx. 2.5 kg). All data in parts by weight. Example V1 V2 1 2 3 Polyol A 80.0 80.0 80.0 80.0 80.0 Polyol B — 12.0 8.0 4.0 — Polyol C 5.0 1.3 2.6 3.8 5.0 Polyol D — 6.7 4.4 2.2 — Polyol E 15.0 — 5.0 10.0 15.0 Isocyanate 2 50.6 — — — — Isocyanate 1 — 50.1 50.4 50.4 50.4 33 LV 0.2 0.2 0.2 0.2 0.2 NE 300 0.3 0.3 0.3 0.3 0.3 BF 2370 1.0 1.0 1.0 1.0 1.0 Water 2.7 2.7 2.7 2.7 2.7 Index 105 105 105 105 105 % by weight of comp. b1 82.5 82.5 82.5 82.5 82.5 % by weight of comp. b2 12.4 12.4 12.4 12.4 12.4 % by weight of comp. b3 5.1 5.1 5.1 5.1 5.1 Further parts by weight of filler — 3.0 2.0 1.0 — styrene-acrylonitrile (comp. b6) Further parts by weight of filler 3.0 — 1.0 2.0 3.0 polyurea (comp. b5)

[0160] Calculation for components b1, b2, b3 of Example 1:

b1: b1 is in all formulations identical (80 parts b1), since polyol is calculated with a correction factor from 97 parts to 100 parts 80*1.031=82.5 parts b1
b2: b2 is always the sum of polyol B+80% polyol E: 8 parts polyol B+0.80*5 parts polyol E=12 parts b2, since polyol is calculated with a correction factor from 97 parts to 100 parts 12*1.031=12.4 parts b2
b3: b3 is always the sum of polyol C+55% polyol D: 2.6 parts polyol C+0.55*4.4 parts polyol D=5.01 parts b3, since polyol is calculated with a correction factor from 97 parts to 100 parts 5.02*1.031=5.1 parts b3

[0161] The amounts by weight indicated by b1, b2, and b3 are % by weight and come to 100% by weight. The amount indicated by styrene-acrylonitrile or polyurea is further parts by weight in addition to 100 parts by weight of components b1, b2, and b3.

TABLE-US-00004 TABLE 4 Mechanical properties of the resulting flexible foams. Example V1 V2 1 2 3 Foam density (kg/m.sup.3) 55.0 53.4 53.5 53.5 53.5 Compression hardness 3.6 7.0 7.2 7.4 7.5 40% (kPa) Hysteresis (%) 19.9 22.2 22.3 22.3 22.0 Tensile strength (kPa) 81 90 88 84 103 Elongation at break (%) 101 86 79 71 89 Rebound resilience (%) 19 41 41 40 40 WCS.sup.2—Loss of hardness — 14.3 13.9 12.2 12.0 (%) FT.sup.1—Loss of hardness (%) — 12.7 12.1 11.3 10.9 FT.sup.1—Loss of height (%) — 2.0 1.8 1.6 1.4 .sup.1FT Fatigue test .sup.2Wet compression set (16 hours, 37?+0C, 80% air humidity)