Method for the reduction of aldehyde emission in polyurethane foam

Abstract

The invention is related to a method for reducing the emission of acetaldehyde and/or propionaldehyde from a polyurethane or polyurea foam, by using a reaction mixture comprising at least one isocyanate reactive component selected from the group consisting of a polyether polyol, a polyester polyol, a polyether polyamine and a polyester polyamine; an isocyanate component; and cyanoacetamide.

Claims

1. A method for reducing the emission of acetaldehyde and/or propionaldehyde from a polyurethane or polyurea foam, the method comprising: forming a reaction mixture by mixing (i) at least one isocyanate reactive component selected from the group consisting of a polyether polyol, a polyester polyol, a polyether polyamine and a polyester polyamine, or combinations thereof, with (ii) an isocyanate component, (iii) a cyanoacetamide (iv) a treating agent selected from the group consisting of a cyclic urea substituted with at least one isocyanate reactive group, a polymer acid and a mixture thereof wherein the polymer acid contains at least three of the same repeating monomers, of either an unsaturated carboxylic acid or an anhydride; or wherein the polymer acid contains at least two repeating monomers, wherein said at least two types of repeating monomers includes a first type of repeating monomer which is an unsaturated carboxylic acid or an anhydride, and a second type of repeating monomer which is different from the first type of repeating monomer; and wherein the amount of cyanoacetamide is from 0.075 parts by weight to 2.0 parts by weight, based on 100 parts by weight of the reaction mixture; and wherein the reaction mixture further comprises a formaldehyde reducing agent which comprises a CH-acidic compound of the formula R.sup.1—CH.sub.2—R.sup.2, wherein Wand R.sup.2 represent an electron-withdrawing radical of the formula —C(O)—R.sup.3, wherein R.sup.3 is selected from the group consisting of —NH—R.sup.4, —NR.sup.5R.sup.6, OR.sup.7 and R.sup.8, wherein 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 and aromatic hydrocarbons which are substituted with one or more isocyanate-reactive groups.

2. A method for reducing the emission of formaldehyde, acetaldehyde, and propionaldehyde from a polyurethane or polyurea foam, the method comprising: forming a reaction mixture by mixing (i) at least one isocyanate reactive component selected from the group consisting of a polyether polyol, a polyester polyol, a polyether polyamine and a polyester polyamine, or combinations thereof, with (ii) an isocyanate component, (iii) a cyanoacetamide, and (iv) a treating agent selected from the group consisting of a cyclic urea substituted with at least one isocyanate reactive group, a polymer acid and a mixture thereof wherein the polymer acid contains at least three of the same repeating monomers, of either an unsaturated carboxylic acid or an anhydride; or wherein the polymer acid contains at least two repeating monomers, wherein said at least two types of repeating monomers includes a first type of repeating which is an unsaturated carboxylic acid or an anhydride, and a second type of repeating monomer which is different from the first type of repeating monomer; wherein the amount of cyanoacetamide is from 0.075 parts by weight to 2.0 parts by weight, based on 100 parts by weight of the reaction mixture; wherein the acetaldehyde emission of the polyurethane or polyurea foam is at least 25% less and the formaldehyde emission of the polyurethane or polyurea foam is at least 50% less than polyurethane or polyurea foam prepared from a mixture identical to the reaction mixture but not comprising the cyanoacetamide; and wherein the reaction mixture further comprises a formaldehyde reducing agent which comprises a CH-acidic compound of the formula R.sup.1—CH.sub.2—R.sup.2, wherein R.sup.1 and R.sup.2 represent an electron-withdrawing radical of the formula —C(O)—R.sup.3, wherein R.sup.3 is selected from the group consisting of —NH—R.sup.4, —NR.sup.5R.sup.6, OR.sup.7 and R.sup.8, wherein 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 and aromatic hydrocarbons which are substituted with one or more isocyanate-reactive groups.

3. The method according to claim 1, wherein said reaction mixture further comprises at least a catalyst selected from blowing and/or gelling catalysts, and optionally fire retardants, antioxidants, surfactants, physical blowing agents, chemical blowing agents, fillers, or pigments.

4. The method according to claim 1, wherein the cyanoacetamide and the at least one isocyanate reactive component are combined prior to mixing with the isocyanate component.

5. The method according to claim 1, wherein the reaction mixture further comprises the formaldehyde reducing agent further comprises: one or more amine components having a structure according to one of the formulae ##STR00015## each of R.sub.a and R.sub.b independently being a random sequence of units R.sub.1, R.sub.2 and/or R.sub.3 wherein R.sub.1 is ##STR00016## R.sub.2 is ##STR00017## R.sub.3 is ##STR00018## and each of said R.sub.4, R.sub.5, R.sub.6 and R.sub.7 individually are —H or —CH.sub.3; and wherein R.sub.a comprises 3 to 17 nitrogen atoms, and R.sub.b comprises 2 to 16 nitrogen atoms.

6. The method according to claim 1, wherein the cyclic urea containing at least one isocyanate reactive group has the formula (I) or (II): ##STR00019## where R′, R.sup.0′, R.sup.1′, R.sup.2′, R.sup.3′, R.sup.4′, R.sup.5′ and R.sup.6′ are independently selected from H, OH, R.sup.11′ OH, NH and COOH, and R.sup.11′ is a C.sub.1-C.sub.4 alkyl group, X is C, O or N with the proviso that when X is O, R.sup.3′ and R.sup.4′ are each zero and when X is N, one of R.sup.3′ or R.sup.4′ is zero, and further with the proviso at least one of R′ or R.sup.0′ is H and that at least: one of R.sup.0′, R.sup.1′, R.sup.2′, R.sup.3′, R.sup.4′, R.sup.5′, R.sup.6′ is OH, COOH, R.sup.11′OH, or NH; or R.sup.1′R.sup.2′ or R.sup.5′R.sup.6′ are NH.sub.2.

7. The method according to claim 1, wherein the cyclic urea containing at least one isocyanate reactive group is selected from the group consisting of 4,5-dihydroxy-2-imidazolidinone, 4,5-dimethoxy-2-imidazolidinone, 4-hydroxyethyl ethylene urea, 4-hydroxy-5-methyl propylene urea, 4-methoxy-5-methyl propylene urea, 4-hydroxy-5,5-dimethyl propylene urea, 1-(2-hydroxyethyl)-2-imidazolidinone and a mixture thereof.

8. The method according to claim 5, wherein said one or more amine components is a mixture comprising at least two of triethylene tetramine (TETA), a tetraethylene pentamine (TEPA), pentaethylene hexamine (PEHA), hexaethylene heptamine, a heptaethylene octamine (HEOA) and octaethylene nonamine.

9. The method according to claim 1, wherein the treating agent is added in amount from 0.01% w to 2.5% w calculated on the total weight of the reaction mixture.

10. The method according to claim 5, wherein the amount of the one or more amine components is from 0.01% w to 2.5% w calculated on the total weight of the reaction mixture.

11. The method of claim 1, wherein the radicals R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are each independently selected from the group consisting of aliphatic hydrocarbons having 1 to 15 carbon atoms, which are substituted by an isocyanate-reactive group.

12. The method according to claim 11, characterized in that each the isocyanate-reactive group in R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 is an —OH, —NH— or —NH.sub.2 group.

Description

EXAMPLE 1

(1) The following table 1 and 2 show the PU formulations used (table 1) and results of the VDA-276 test (Table 2). To the polyol formulation the polyisocyanate compound Suprasec 2447 (from Huntsman) is added at an index of 80 to make the polyurea foam. For each formulation about 1 kg foam was made via hand mix foam procedure for the VDA-276 emission test (air sampling after 4 h, at 65° C./5% Rel humidity and 0.4 EA/hour).

(2) It is indicated how much of the aldehyde scavenger is added. Cyanoacetamide is able to reduce the acetaldehyde. Further, it is shown a combination of cyanoacetamide with an ethylene amine and a polymeric acid reduces the emission of formaldehyde and acetaldehyde. Also the propionaldehyde emission is reduced when using a combination of cyanoacetamide with an ethylene amine and a polymeric acid.

(3) TABLE-US-00001 TABLE 1 Polyol formulation. All the components are available from Huntsman International LLC except for Tegostab B 8734 LF-2 which is available from Evonik and Cyanoacetamide available from Sigma Aldrich. REF 1* REF 2 Exp 1 Exp 2 Exp 3 Exp 4 Daltocel F 428 (wt % in view of polyol formulation) 90 90 89.8 89.85 89.75 89.5 Daltocel F526 (wt % in view of polyol formulation) 4 4 4 4 4 4 DELA (wt % in view of polyol formulation) 0.25 0.25 0.25 0.25 0.25 0.25 Tegostab B 8734 LF-2 (wt % in view of 0.9 0.9 0.9 0.9 0.9 0.9 polyol formulation) Water (wt % in view of polyol formulation) 3.7 3.7 3.7 3.7 3.7 3.7 JEFFCAT LED-103 (wt % in view of polyol formulation) 0.15 0.15 0.15 0.15 0.15 0.15 JEFFCAT DPA (wt % in view of polyol formulation) 1 1 1 1 1 1 Acetaldehyde content added in polyol (ppm)** 1.5 1.5 1.5 1.5 1.5 TEPA in wt % (available from Huntsman) 0.2 0.17 0.34 Polyacrylic acid Mw 5000 in wt % 0.1 0.08 0.17 Cyanoacetamide in wt % 0.15 0.075 0.15

(4) TABLE-US-00002 TABLE 2 Results of VDA-276 chamber emission. VDA276 aldehyde emissions from foam (in μg/m.sup.3/kg foam) REF 1 REF 2 Exp 1 Exp 2 Exp 3 Exp 4 Formaldehyde 224 231 9 25 4 1 Acetaldehyde 33 154 178 88 108 84 Propionaldehyde 407 454 502 302 265 244 Total aldehydes 664 839 689 415 377 329 * In REF 1 there is no extra acetaldehyde added to the polyol composition. **The acetaldehyde is added by mixing the polyol with 4.2 parts of polyol to which 36.4 ppm acetaldehyde was added.

EXAMPLE 2

(5) The following formulation was used to make polyurethane foam.

(6) TABLE-US-00003 TABLE 3 Polyol formulation. Daltocel F428 (wt % in view of the polyol formulation) 94 Water (wt % in view of the polyol formulation) 3.8 Jeffcat ZF10 (wt % in view of the polyol formulation) 0.1 Jeffcat DPA (wt % in view of the polyol formulation) 1 Diethanolamine (wt % in view of the polyol formulation) 0.2 Tegostab B8734LF2 (wt % in view of the polyol formulation) 0.9 Subtotal of polyol formulation 100

(7) To this formulation, Isocyanate (pure MDI 2,4′ MDI/4,4′ MDI: 50/50/Suprasec 2185: 80/20) (in pbw) is added at an index of 91 to make the polyurethane foam. For each formulation about 1 kg foam was made via hand mix foam procedure for the VDA-276 emission test (air sampling after 4 h, at 65° C./5% Rel humidity and 0.4 EA/hour). The following tables show the results of the VDA-276 test of the above described foam. It is indicated how much of the aldehyde scavengers are added. All the aldehyde scavengers were first added to the polyol formulation and then the isocyanate is added.

(8) TABLE-US-00004 TABLE 4 Example not according to the invention. Addition of formaldehyde scavenger 2-cyano-N-methyl-acetamide. REF 3 Exp 5 Acetaldehyde added to polyol (ppm) 0.8 0.8 2-cyano-N-methyl-acetamide (wt %) 0.25 VDA276 aldehyde emissions from foam (in μg/m.sup.3/kg foam) Formaldehyde 162 63 Acetaldehyde 54 55 Propionaldehyde 182 198

(9) TABLE-US-00005 TABLE 5 Example not according to the invention. Addition of formaldehyde scavenger ethyl cyanoacetate REF 4 Exp 6 Acetaldehyde added to polyol (ppm) 0.8 0.8 Ethyl cyanoacetate (wt %) 0.25 VDA276 aldehyde emissions from foam (in μg/m.sup.3/kg foam) Formaldehyde 153 56 Acetaldehyde 43 58 Propionaldehyde 187 212

(10) Exp 5 and 6 show that the scavenging of formaldehyde does not mean that acetaldehyde and propionaldehyde are scavenged. Indeed, ethyl cyanoacetate and 2-cyano-N-methyl-acetamide are able to reduce the emission of formaldehyde, but do not have an effect on the emission of acetaldehyde and propionaldehyde. This suggests that the mechanism of scavenging of these 3 different aldehydes is different.