PROCESS FOR REDUCING ALDEHYDE EMISSIONS IN POLYETHER POLYOLS AND POLYURETHANE FOAMS

Abstract

Polyurethane foams are made by curing a reaction mixture that contains an aromatic polyisocyanate, at least one iso-cyanate-reactive material having an average functionality of at least 2 and an equivalent weight of at least 200 per isocyanate-reactive group, at least one blowing agent, at least one surfactant and at least one catalyst, a certain β-diketone compound and a water-soluble amino-functional polymer. Foams so produced emit low levels of aldehydes.

Claims

1. A process for producing a polyurethane foam comprising forming a reaction mixture that contains an aromatic polyisocyanate, at least one isocyanate-reactive material having an average functionality of at least 2 and an equivalent weight of at least 200 grams per mole of isocyanate-reactive groups, at least one blowing agent, at least one surfactant and at least one catalyst, and curing the reaction mixture to form the polyurethane foam, wherein the curing step is performed in the presence of (i) at least one β-diketone compound, wherein the β-diketone compound is a compound represented by structure I: ##STR00013## wherein R.sup.1 and R.sup.2 are independently selected from hydrogen, —NH.sub.2, —NH—R.sup.3—N(R.sup.4).sub.2, —OR.sup.4 and —R.sup.4, wherein each R.sup.3 and R.sup.4 is independently unsubstituted hydrocarbon or hydrocarbon substituted with one or more of O, N, S, P or halogen, with the proviso that R.sup.1 and R.sup.2 together may form a divalent radical and further provided that at least one of R.sup.1 and R.sup.2 is not hydrogen, and (ii) at least one water-soluble, amino-functional polymer having a number average molecular weight of at least 300 and at least 3 primary and/or secondary amino groups per molecule.

2. A process for reducing aldehyde emissions from a polyurethane foam, comprising: a) combining (i) at least one β-diketone compound is a compound represented by structure I: ##STR00014## wherein R.sup.1 and R.sup.2 are independently selected from hydrogen, —NH.sub.2, —NH—R.sup.3—N(R.sup.4).sub.2, —OR.sup.4 and —R.sup.4, wherein each R.sup.3 and R.sup.4 is independently unsubstituted hydrocarbon or hydrocarbon substituted with one or more of O, N, S, P or halogen, with the proviso that R.sup.1 and R.sub.2 together may form a divalent radical and further provided that at least one of R.sup.1 and R.sup.2 is not hydrogen, and (ii) at least one water-soluble, amino-functional polymer having a number average molecular weight of at least 300 and at least 3 primary and/or secondary amino groups per molecule, with at least one isocyanate-reactive material having an average functionality of at least 2 and an equivalent weight of at least 200 grams per mole of isocyanate-reactive groups to form a mixture and then b) combining the mixture from step a) with at least one organic polyisocyanate and curing the resulting reaction mixture in the presence of at least one blowing agent, at least one surfactant and at least one catalyst to form a polyurethane foam.

3. The process of claim 1 wherein the β-diketone compound is an acetoacetate ester or amide is characterized by having one or more acetoacetate ester or acetoacetate amide groups having structure II: ##STR00015## wherein R.sup.5 is a substituted or unsubstituted C.sub.1-C.sub.6 alkyl or a substituted or unsubstituted aryl group, and X is —O— in the case of an ester and —NH— in the case of an amide.

4. The process of claim 3 wherein the β-diketone compound is N-(2-hydroethyl)acetoacetamide or (acetoacetoxy)ethyl methacrylate.

5. The process of claim 1 wherein the the β-diketone compound is a 3-oxopropanamide compound represented by structure IV: ##STR00016## wherein R.sup.8 is hydrogen or a hydrocarbon group, R.sup.6 is hydrogen, hydrocarbon, hydroxyalkyl or aminoalkyl, R.sup.7 is hydroxyalkyl or aminoalkyl, and n is at least 1.

6. The process of claim 1 wherein the β-diketone compound is represented by the structure ##STR00017## wherein X, Y, Z are independently carbonyl, —C(R.sup.9R.sup.10)—, —NR.sup.11—, —O— or a chemical bond, each R.sup.9 and R.sup.10 are independently H, a substituted or unsubstituted linear or branched alkyl or alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted phenyl group, a halogen, —CO.sub.2CH.sub.3, or —CN, with the proviso that any two or more of R.sup.9 and R.sup.10 may be connected intra- or inter-molecularly and each R.sup.11is independently H, a substituted or unsubstituted linear or branched alkyl or alkylene group having 1 to 10 carbon atoms or a substituted or unsubstituted phenyl group.

7. The process of claim 1 wherein the water-soluble, amino-functional polymer is a polyethyleneimine.

8. A polyurethane foam made in the process of claim 1.

9. A process for reducing aldehyde emissions from a polyether polyol, comprising combining 0.01 to 5 parts by weight of at least one β-diketone compound and 0.01 to 5 parts by weight of at least one water-soluble, amino-functional polymer having a number average molecular weight of at least 300 and at least 3 primary and/or secondary amino groups per molecule with 100 parts by weight of the polyether polyol, wherein the β-diketone compound is represented by structure I: ##STR00018## wherein R.sup.1 and R.sup.2 are independently selected from hydrogen, —NH.sub.2, —NH—R.sup.3—N(R.sup.4).sub.2, —OR.sup.4 and —R.sup.4, wherein each R.sup.3 and R.sup.4 is independently unsubstituted hydrocarbon or hydrocarbon substituted with one or more of O, N, S, P or halogen, with the proviso that R.sup.1 and R.sup.2 together may form a divalent radical and further provided that at least one of R.sup.1 and R.sup.2 is not hydrogen.

10. The process of claim 9 wherein the β-diketone compound is an acetoacetate ester or amide is characterized by having one or more acetoacetate ester or acetoacetate amide groups having structure II: ##STR00019## wherein R.sup.5 is a substituted or unsubstituted C.sub.1-C.sub.6 alkyl or a substituted or unsubstituted aryl group, and X is —O— in the case of an ester and —NH— in the case of an amide.

11. The process of claim 10 wherein the β-diketone compound is N-(2-hydroethyl)acetoacetamide or (acetoacetoxy)ethyl methacrylate.

12. The process of claim 9 wherein the the β-diketone compound is a 3-oxopropanamide compound represented by structure IV: ##STR00020## wherein R.sup.8 is hydrogen or a hydrocarbon group, R.sup.6 is hydrogen, hydrocarbon, hydroxyalkyl or aminoalkyl, R.sup.7 is hydroxyalkyl or aminoalkyl, and n is at least 1.

13. The process of claim 9 wherein the β-diketone compound is represented by the structure ##STR00021## wherein X, Y, Z are independently carbonyl, —C(R.sup.9R.sup.10)—, —NR.sup.11—, —O— or a chemical bond, each R.sup.9 and R.sup.10 are independently H, a substituted or unsubstituted linear or branched alkyl or alkylene group having 1 to 10 carbon atoms, a substituted or unsubstituted phenyl group, a halogen, —CO.sub.2CH.sub.3, or —CN, with the proviso that any two or more of R.sup.9 and R.sup.10 may be connected intra- or inter-molecularly and each R.sup.11 is independently H, a substituted or unsubstituted linear or branched alkyl or alkylene group having 1 to 10 carbon atoms or a substituted or unsubstituted phenyl group.

14. The process of claim 9 wherein the water-soluble, amino-functional polymer is a polyethyleneimine.

15. A polyether polyol having a hydroxyl equivalent weight of at least 200 grams per equivalent of hydroxyl groups, which polyether polyol contains 0.01 to 5 parts by weight of at least one β-diketone compound and 0.01 to 5 parts by weight of at least one water-soluble, amino-functional polymer having a number average molecular weight of at least 300 and at least 3 primary and/or secondary amino groups per molecule with 100 parts by weight of the polyether polyol, wherein the β-diketone compound is represented by structure I: ##STR00022## wherein R.sup.1 and R.sup.2 are independently selected from hydrogen, —NH.sub.2, —NH—R.sup.3—N(R.sup.4).sub.2, —OR.sup.4 and —R.sup.4, wherein each R.sup.3 and R.sup.4 is independently unsubstituted hydrocarbon or hydrocarbon substituted with one or more of O, N, S, P or halogen, with the proviso that R.sup.1 and R.sup.2 together may form a divalent radical and further provided that at least one of R.sup.1 and R.sup.2 is not hydrogen.

Description

EXAMPLE 1 AND COMPARATIVE SAMPLES A-C

[0086] General Foaming Method, Comparative Sample A: A formulated polyol is made by combining 40 parts of a nominally trifunctional polyether polyol having a hydroxyl number of 29.5, 52.6 parts of a 1700 equivalent weight polyether polyol initiated from a mixture of sucrose and glycerine, 0.8 part of glycerin, 1.6 parts of a urethane catalyst mixture, 0.5 parts of an organosilicone foam-stabilizing surfactant and 4.2 parts of water. Polyurethane foams are made from the formulated polyol by combining the formulated polyol with an isocyanate-terminated prepolymer at a 1.67:1 weight ratio, pouring the resulting reaction mixture into a cup and allowing the reaction mixture to rise and cure to form a polyurethane foam. After the foam has cured enough to be dimensionally stable, it is removed from the cup and, except for Comparative Samples B and C, 10 cm×10 cm×14 cm samples, weighing about 38 to 41 grams are cut. For Comparative Samples B and C, 30 gram samples are cut. The foam cubes each are immediately wrapped in aluminum foil to form an air-tight package for 7 days.

[0087] Comparative Samples B and C are made using the general foaming method. In Comparative Sample B, a 600 MW polyethylene imine (PEI) (0.05% based on formulated polyol weight, 0.054% based on isocyanate reactive materials of 200 g/mol or greater equivalent weight) is added to the formulated polyol before making the foam. In Comparative Sample B, N-(2-hydroxyethyl)acetoacetamide N-AAEM) (0.1% based on formulated polyol weight, 0.108% based on isocyanate reactive materials of 200 g/mol or greater equivalent weight) is added to the formulated polyol before making the foam.

[0088] Example 1 is made in using the general foaming method. In Example 1, both the 600 MW PEI (0.05% based on formulated polyol weight, 0.054% based on isocyanate reactive materials of 200 g/mol or greater equivalent weight) and N-AAEM (0.1% based on formulated polyol weight, 0.108% based on isocyanate reactive materials of 200 g/mol or greater equivalent weight) are added to the formulated polyol before making the foam.

[0089] Aldehydes emitted from the foam samples are analyzed using the Toyota gas bag method. The cubed foam samples are in each case removed from the foil and put into a 10 L Tedlar gas bag that has been washed with pure nitrogen three times and emptied. An empty gas bag is used as a blank. After the foam sample is put into the gas bag, the bag is filled with about 7 L of nitrogen gas and heated in the oven for 2 hours at 65° C. The nitrogen gas in the gas bag is then pumped out by an air pump and analyzed for formaldehyde, acetaldehyde, acrolein and propionaldehyde.

[0090] The gas from each bag is passed through a dinitrophenylhydrazine (DNPH) cartridge (CNWBOND DNPH-Silica cartridge, 350 mg, Cat. No. SEEQ-144102, Anple Co., Ltd.) at a sampling speed is 330 mL/min The aldehydes emitted from the foam into the gas are absorbed by the cartridge to form DNPH derivatives. The DNPH cartridge is eluted with 3 g of acetonitrile, and the resulting acetonitrile solution is analyzed by HPLC to quantify the carbonyls in the sample, as follows.

[0091] A standard solution containing 15 μg/mL each of formaldehyde, acetaldehyde, acrolein and propionaldehyde (in each case in the form of DNPH derivatives) (TO11A carbonyl-DNPH mix, Cat. No. 48149-U, Supelco Co., Ltd) is diluted with acetonitrile. A vial containing 2 mL of the diluted solution (containing 0.794 ppm of each of formaldehyde, acetaldehyde, acrolein and propionaldehyde) is refrigerated to −4° C. The refrigerated solution is injected into the HPLC system and analyzed for formaldehyde, acetaldehyde, acrolein and propionaldehyde derivatives. The response factor is calculated from the area of the elution peak for each derivative, according the formula:

[00001]$\mathrm{Response}\mathrm{factor}i=\frac{\mathrm{Peak}\mathrm{Area}i}{0.794}$

where Response factor i=Response factor of derivative i; Peak Area i=Peak Area of derivative i in standard solution and 0.794=the concentration of each derivative in the standard solution.

[0092] The amounts of formaldehyde, acetaldehyde, acrolein, and propionaldehyde emitted by each foam sample are then determined. In each case, the acetonitrile solution obtained by eluting the DNPH column is injected into the HPLC system and the area of the elution peak is determined from each derivative. The concentration of the aldehyde-DNPH derivative in the sample solution is calculated as follows:

[00002]$\mathrm{Concentration}\mathrm{of}i=\frac{\mathrm{Peak}\mathrm{Area}i}{\mathrm{Response}\mathrm{factor}i}$

where: Concentration of i=Concentration of aldehyde—DNPH derivative in the sample solution, Peak Area i=Peak Area of Derivative i in sample solution and Response factor i=Response factor of derivative i, determined from the standard solutions as described above.

[0093] The HPLC conditions are as follows:

TABLE-US-00001 Instrument: Agilent 1200 HPLC Column: Supelco Ascentis Express C18, 15 cm*4.6 mm, 2.7 um Mobile Phase: Solvent A: 0.1% H.sub.3PO.sub.4 in Acetonitrile Solvent B: 0.1% H.sub.3PO.sub.4 in DI water Column Oven: 15° C. Detection: DAD detector at 360 nm Gradient: Time (mn) % A % B Flow (mL/min) 0 45 55 1 7 45 55 1 14 50 50 1 20 85 15 1 25 100 0 1 Equilibration 5 min Time: Injection: 10 uL

[0094] The concentrations of formaldehyde, acetaldehyde acrolein and propionaldehyde for each of Example 1 and Comparative Samples A-C are as indicated in Table 1.

TABLE-US-00002 TABLE 1 Comp. B* Comp. C* Ex. 1 Sample Comp. A* 0.054% 0.108% 0.054% PEI + Additives None PEI N-AAEM 0.108% N-AAEM Formaldehyde, 397 413 101 65 μg/m.sup.3 Acetaldehyde, 217 374 237 97 μg/m.sup.3 Acrolein, 1061 937 167 54 μg/m.sup.3 Propionaldehyde, 362 613 769 315 μg/m.sup.3 *Not an example of this invention.

[0095] As the data in Table 1 shows, PEI by itself provides no benefit in reducing the levels of any of the aldehydes tested. N-AAEM is effective only for reducing formaldehyde and acrolein. The combination of PEI and N-AAEM leads to large reductions in all four aldehydes tested, in each case to levels much lower than are achieved using either PEI or N-AAEM by itself. These results are quite surprising given that PEI by itself in provides very little benefit; combining it with N-AAEM would not be expected to lead to any better performance than that of N-AAEM by itself.

EXAMPLE 2 AND COMPARATIVE SAMPLES D-F

[0096] Comparative Sample D is a repeat of Comparative Sample A.

[0097] Comparative Samples E and F are made using the general foaming method. In Comparative Sample E, 0.05% of the 600 MW polyethylene imine (PEI) (0.05% based on formulated polyol weight, 0.054% based on isocyanate reactive materials of 200 g/mol or greater equivalent weight)) is added to the formulated polyol before making the foam. In Comparative Sample F, (acetoacetoxy)ethyl methacrylate (AAEM) (0.1% based on formulated polyol weight, 0.108% based on isocyanate reactive materials of 200 g/mol or greater equivalent weight) is added to the formulated polyol before making the foam.

[0098] Example 2 is made in using the general foaming method. In Example 2, both the 600 MW PEI (0.05% based on formulated polyol weight, 0.054% based on isocyanate reactive materials of 200 g/mol or greater equivalent weight) and AAEM (0.1% based on formulated polyol weight, 0.108% based on isocyanate reactive materials of 200 g/mol or greater equivalent weight) are added to the formulated polyol before making the foam.

[0099] The foams are tested as indicated in the previous examples. Results are as indicated in Table 2.

TABLE-US-00003 TABLE 2 Comp. E* Comp. F* Ex. 1 Sample Comp. D* 0.054% 0.108% 0.054% PEI + Additives None PEI AAEM 0.108% AAEM Formaldehyde, 400 306 39 29 μg/m.sup.3 Acetaldehyde, 189 207 155 90 μg/m.sup.3 Acrolein, 736 541 158 38 μg/m.sup.3 Propionaldehyde, 478 495 476 245 μg/m.sup.3 *Not an example of this invention.

[0100] In this set of experiments, PEI by itself provides benefit in reducing the acrolein level, but not that of any of the other aldehydes. AAEM by itself moderately reduces the formaldehyde, acetaldehyde and acrolein emissions, but not propionaldehyde emissions. The combination of PEI and AAEM leads to large reductions in all four aldehydes tested, in each case to levels much lower than are achieved using either PEI or N-AAEM by itself. Again, these results are quite surprising given that PEI by itself in provides very little benefit.