FLEXIBLE POLYURETHANE FOAMS BASED ON POLYOXYMETHYLENE-POLYOXYALKYLENE BLOCK COPOLYMERS

Abstract

The present invention relates to a method for producing flexible polyurethane foams based on polyoxymethylene-polyoxyalkylene block copolymers. The invention also relates to the use of the flexible polyurethane foams thus produced and their use for producing furniture upholstery, textile inlays, mattresses, automobile seats, headrests, armrests, sponges, foam sheets for use in automobile parts such as roof linings, door panel upholstery, seat covers and technical components. The invention finally relates to a two-component system for producing flexible polyurethane foams.

Claims

1. A process for producing flexible polyurethane foams by reacting a component A comprising A1 5 to 85 parts by weight of at least one polyoxymethylene-polyoxyalkylene block copolymer comprising two polyoxyalkylene blocks and having a hydroxyl number according to DIN EN ISO 4629-1:2016-12 of 5 mg KOH/g to 56 mg KOH/g, wherein the two polyoxyalkylene blocks are terminal; A2 0 to 95 parts by weight of at least one compound having 2 to 6 Zerewitinoff-active H atoms comprising at least one of polyether polyols, polyester polyols, polyether ester polyols, polycarbonate polyols, or polyacrylate polyols; A3 0.1 to 25 parts by weight based on a sum of the parts by weight of the components A1 and A2 of water and/or physical blowing agents, A4 0 to 10 parts by weight based on a sum of the parts by weight of the components A1 and A2 of at least one compound which has at least 2 Zerewitinoff-active H atoms and is distinct from A2; A5 0 to 10 parts by weight based on a sum of the parts by weight of the components A1 and A2 of auxiliary and additive substances; with a component B comprising B1 at least one di- and/or polyisocyanate having an average NCO functionality of 2.0 to 2.6; wherein the reaction of the component A with the component B is performed in the presence of a catalyst and at an isocyanate index of 50 to 130, and wherein all reported parts by weight of the components A1 to A5 are normalized such that the parts by weight of A1+A2 in the composition sum to 100 parts by weight.

2. A process for producing flexible polyurethane foams by reacting a component A comprising A11 0 to 85 parts by weight of at least one polyoxymethylene-polyoxyalkylene block copolymer comprising two polyoxyalkylene blocks and having a hydroxyl number according to DIN EN ISO 4629-1:2016-12 of 5 mg KOH/g to 56 mg KOH/g wherein the two polyoxyalkylene blocks are terminal; A12 0 to 100 parts by weight of at least one compound having 2 to 6 Zerewitinoff-active H atoms comprising at least one of polyether polyols, polyester polyols, polyether ester polyols, polycarbonate polyols or polyacrylate polyols; A13 0.1 to 25 parts by weight based on a sum of the parts by weight of the components A11 and A12 of water and/or physical blowing agents, A14 0 to 10 parts by weight based on a sum of the parts by weight of the components A11 and A12 of at least one compound which has at least 2 Zerewitinoff-active H atoms and is distinct from A2; A15 0 to 10 parts by weight based on a sum of the parts by weight of the components A11 and A12 of auxiliary and additive substances; with a component B comprising B2 at least one prepolymer having an NCO content of 18% to 40% by weight of NCO and obtained by reaction of A1 5 to 18 parts by weight of at least one polyoxymethylene-polyoxyalkylene block copolymer comprising two polyoxyalkylene blocks and having a hydroxyl number according to DIN EN ISO 4629-1:2016-12 of 5 mg KOH/g to 56 mg KOH/g, wherein the two polyoxyalkylene blocks are terminal; A2 optionally further isocyanate-reactive or inert components containing no polyoxymethylene; with B1 at least one di- and/or polyisocyanate having an average NCO functionality of 2.0 to 2.6, optionally in the presence of a catalyst, wherein the parts by weight of B1 are based on the sum of the parts by weight of A1 and A2 which are normalized to 100 parts by weight; wherein the reaction of the component A with the component B is performed in the presence of a catalyst and at an isocyanate index of 50 to 130, and wherein all reported parts by weight of the components A11 to A15 are normalized such that the parts by weight of A11+A12 in the composition sum to 100 parts by weight.

3. The process as claimed in claim 1, wherein the polyoxymethylene block of the polyoxymethylene-polyoxyalkylene block copolymer A1 has a weight-average molecular weight of 62 to 30000 g/mol measured by gel permeation chromatography using polystyrene standards.

4. The process as claimed in claim 1, wherein the polyoxymethylene-polyoxyalkylene block copolymer A1 has the following formula (I):
HO-(alkO).sub.x(CH.sub.2O).sub.n-(alkO).sub.yOH(I), wherein alkO is a structural unit which independently in each structural unit is derived from ethylene oxide, propylene oxide, butylene oxide, or styrene oxide; x is 2 to 100; y is 2 to 100; and n=5 to 100.

5. The process as claimed in claim 1, wherein A2 is a polypropylene oxide-polyethylene oxide block copolymer having an average functionality between 2.7 and 6, having a hydroxyl number according to DIN EN ISO 4629-1:2016-12 of 26 mg KOH/g to 56 mg KOH/g and a ratio of propylene oxide to ethylene oxide of 0.1 to 9:1.

6. The process as claimed in claim 1, wherein at least one di- and/or polyisocyanate B1 derives from MDI or TDI or mixtures thereof.

7. The process as claimed in claim 1, wherein the catalyst is a catalyst which reacts with an isocyanate to afford urethanes, ureas, allophanates, or biurets.

8. A flexible polyurethane foam obtainable by a process as claimed in claim 1.

9. The flexible polyurethane foam as claimed in claim 9, having an apparent density of 0.02 to 0.8 kg/dm.sup.3 measured according to DIN ISO 845:2009-10.

10. The flexible polyurethane foam according to claim 9, wherein the flexible polyurethane foam meets horizontal burning rate requirements based on guideline 95/28/EC and standard FMVSS 302.

11. (canceled)

12. A two-component system for producing flexible polyurethane foams from a component A comprising A1 5 to 85 parts by weight of at least one polyoxymethylene-polyoxyalkylene block copolymer comprising two polyoxyalkylene blocks and having a hydroxyl number according to DIN EN ISO 4629-1:2016-12 of 5 mg KOH/g to 56 mg KOH/g, wherein the two polyoxyalkylene blocks are terminal; A2 0 to 95 parts by weight of at least one compound having 2 to 6 Zerewitinoff-active H atoms comprising at least one of polyether polyols, polyester polyols, polyether ester polyols, polycarbonate polyols, or polyacrylate polyols, A3 0.1 to 25 parts by weight based on a sum of the parts by weight of the components A1 and A2 of water and/or physical blowing agents, A4 0 to 10 parts by weight based on a sum of the parts by weight of the components A1 and A2 of at least one compound which has at least 2 Zerewitinoff-active H atoms and is distinct from A2; A5 0 to 10 parts by weight based on a sum of the parts by weight of the components A1 and A2 of auxiliary and additive substances; and a component B comprising B1 at least one di- and/or polyisocyanate having an average NCO functionality of 2.0 to 2.6; and at least one catalyst, wherein the component A and the component B are present in a ratio of an isocyanate index of 50 to 130, and wherein all reported parts by weight of the components A1 to A5 are normalized such that the parts by weight of A1+A2 in the composition sum to 100 parts by weight.

13. A two-component system for producing flexible polyurethane foams from a component A comprising A11 0 to 85 parts by weight of at least one polyoxymethylene-polyoxyalkylene block copolymer comprising two polyoxyalkylene blocks and having a hydroxyl number according to DIN EN ISO 4629-1:2016-12 of 5 mg KOH/g to 56 mg KOH/g, wherein the two polyoxyalkylene blocks are terminal; A12 0 to 100 parts by weight of at least one compound having 2 to 6 Zerewitinoff-active H atoms comprising at least one of polyether polyols, polyester polyols, polyether ester polyols, polycarbonate polyols, or polyacrylate polyols; A13 0.1 to 25 parts by weight based on a sum of the parts by weight of the components A11 and A12 of water and/or physical blowing agents, A14 0 to 10 parts by weight based on a sum of the parts by weight of the components A11 and A12 of at least one compound which has at least 2 Zerewitinoff-active H atoms and is distinct from A2; A15 0 to 10 parts by weight based on a sum of the parts by weight of the components A11 and A12 of auxiliary and additive substances; with a component B comprising B2 at least one prepolymer having an NCO content of 18-40% by weight of NCO and obtained by reaction of A1 5 to 18 parts by weight of at least one polyoxymethylene-polyoxyalkylene block copolymer two polyoxyalkylene blocks and having a hydroxyl number according to DIN EN ISO 4629-1:2016-12 of 5 mg KOH/g to 56 mg KOH/g, wherein the two polyoxyalkylene blocks are terminal; A2 optionally further isocyanate-reactive or inert components containing no polyoxymethylene; B1 at least one di- and/or polyisocyanate having an average NCO functionality of at least 2.0 to 2.6, optionally in the presence of a catalyst, wherein the parts by weight of B1 are based on the sum of the parts by weight of A1 and A2 which are normalized to 100 parts by weight; and at least one catalyst, wherein the component A and the component B are present in a ratio of an isocyanate index of 50 to 130 and wherein all reported parts by weight of the components A11 to A15 are normalized such that the parts by weight of A11+A12 in the composition sum to 100 parts by weight.

14. The process as claimed in claim 4-2, wherein the polyoxymethylene block of the polyoxymethylene-polyoxyalkylene block copolymer A11 has a weight-average molecular weight of 62 to 30000 g/mol measured by gel permeation chromatography using polystyrene standards.

15. The process as claimed in claim 2, wherein the polyoxymethylene-polyoxyalkylene block copolymer A11 has the following formula (I):
HO-(alkO).sub.x(CH.sub.2O).sub.n-(alkO).sub.yOH(I), wherein alkO is a structural unit which independently in each structural unit is derived from ethylene oxide, propylene oxide, butylene oxide, or styrene oxide; x is 2 to 100; y is 2 to 100; and n=5 to 100.

16. The process as claimed in claim 2, wherein A12 is a polypropylene oxide-polyethylene oxide block copolymer having an average functionality between 2.7 and 6, having a hydroxyl number according to DIN EN ISO 4629-1:2016-12 of 26 mg KOH/g to 56 mg KOH/g and a ratio of propylene oxide to ethylene oxide of 0.1 to 9:1.

17. The process as claimed in claim 2, wherein at least one di- and/or polyisocyanate B1 derives from MDI or TDI or mixtures thereof.

18. The process as claimed in claim 2, wherein the catalyst is a catalyst which reacts with an isocyanate to afford urethanes, ureas, allophanates, or biurets.

Description

EXAMPLES

[0171] Input Materials

TABLE-US-00001 A1 Polyoxymethylene-polypropylene oxide block copolymer (OH number 59 mg KOH/g, 22% by weight POM) produced by addition of propylene oxide onto polyoxymethylene with DMC catalysis. A2 Polyoxymethylene-polypropylene oxide block copolymer (OH number 41 mg KOH/g, 17% by weight POM) produced by addition of propylene oxide onto polyoxymethylene with DMC catalysis. A3 Mixture of a sorbitol-started polypropylene oxide-polyethylene oxide block copolymer (OH number 29 mg KOH/g, propylene oxide:ethylene oxide = 3:1 mol/mol, ethylene oxide as end blocks) and A1 in a weight ratio of 71:29. The average OH number is 37 mg KOH/g. A4 Mixture of a sorbitol-started polypropylene oxide-polyethylene oxide block copolymer (OH number 29 mg KOH/g, propylene oxide:ethylene oxide = 3:1 mol/mol, ethylene oxide as end blocks) and A2 in a weight ratio of 62:38. The average OH number is 36 mg KOH/g. A5 Propylene glycol-started polypropylene glycol having an OH number of 56 mg KOH/g (contains neither polyoxymethylene units nor ethylene oxide units). A7 Sorbitol-started polypropylene oxide-polyethylene oxide copolymer (OH number 96 mg KOH/g, propylene oxide:ethylene oxide = 1:5.9 mol/mol), employed as a cell opener. A8 Glycerol-started polypropylene oxide-polyethylene oxide copolymer (OH number 35 mg KOH/g, propylene oxide:ethylene oxide = 5:1 mol/mol). B1 Polymeric isocyanate (viscosity 0.2 Pa*s at 25 C., NCO content of 7.5 mol/kg). B2 Uretdione-modified 4,4-methylenediisocyanate (viscosity of 0.055 Pa*s at 25 C., NCO content of 7.0 mol/kg), produced from 4,4-methylene diisocyanate with 1- methylphospholene-1-oxide as a catalyst. B3 Stock solution of hydrogen chloride in a mixture of 4,4-methylene diisocyanate and 2,4-methylene diisocyanate in a 9:11 ratio.

[0172] Production of the Prepolymers:

[0173] The components B1, B2 and B3 are mixed at room temperature and heated to 80 C. The components A1 or A2 are added dropwise over 30 minutes at this temperature. The mixture is kept at 80 C. for two hours. After cooling to 20 C. the reaction mixture is filled into aluminum bottles. Pp1=prepolymer according to the present invention. CPp2=comparative prepolymer

TABLE-US-00002 CPp2 Pp1 Comparative B1 37.5 37.5 parts by wt. B2 50.0 50.0 parts by wt. B3 0.1 0.1 parts by wt. A1 12.4 parts by wt. A2 12.4 parts by wt. Sum 100 100 parts by wt. Calculated POM content 21.5 27.8 g/kg NCO content according to 6.18 6.12 mol/kg DIN 53185 (1997) Viscosity at 25 C. according 0.20 0.22 Pa*s to DIN 53019-1 (September 2008)

[0174] The prepolymer based on the polyol A2 has a 9% better viscosity.

[0175] Production of the Foams:

[0176] The ratio of isocyanate groups to isocyanate-reactive groups multiplied by 100 is described as the index. The following tests always compare foams produced using the same index. Indices of 70 and 90 were established in two test series as nowadays also employed analogously in the market for molded seats.

[0177] To produce the foams the required amount of polyol is initially charged into a cardboard beaker having a sheet metal bottom (volume: about 850 ml) and loaded with air using a stirring means (Pendraulik) fitted with a standard stirring disk (d=64 mm) at 4200rpm for 45 seconds. Homogenization is carried out using the Pendraulik standard stirring disk (diameter 64 mm).

[0178] The isocyanate/isocyanate mixture/prepolymer is weighed into a suitable beaker and emptied again (efflux time: 3 s). This beaker still having wet internal walls is tared and refilled with the reported isocyanate quantity. The isocyanate is added to the polyol formulation (efflux time: 3 s). The mixture is subjected to intensive mixing for 5 seconds using a stirring means (Pendraulik). A stopwatch is started at commencement of the mixing and the characteristic reaction times are read-off therefrom. About 93 g of the reaction mixture are poured into a teflon film-lined aluminum box mold having a volume of 1.6 dm.sup.3 and a temperature of 23 C. The mold is closed and bolted. After six minutes the mold is unbolted, decompressed and the mold pressure is qualitatively assessed via the height by which the mold lid has been raised by the molding [mm] The demolded foam cushion is qualitatively assessed for reaction completeness and for skin and pore structure. The reaction kinetics are determined using the residual reaction mixture in the beaker. [0179] The cream time has been attained when a first foaming of the mixture is observable. This indicates the beginning of the reaction between isocyanate and water. [0180] The fiber time has been attained when strings can be pulled from the surface of the rising foam by dabbing with a wooden spatula. Alternatively, lumps form on the wooden spatula. [0181] The rise time has been attained when the foam finally ceases to expand. It should be noted here that some systems have a propensity to undergo some sagging before rising again.

[0182] Polyol Formulations

[0183] The additive base mixture comprises 12.0% by weight of glycerol, 20.5% by weight of the polyether-modified siloxane Tegostab B8734 LF2 (OH number 83 mg KOH/g), 61.6% of water and 6.0% by weight of the blowing catalyst N-[2-dimethylamino)ethoxy]ethyl]-N-methyl-1,3-propanediamine

[0184] Tegostab is an Evonik brand.

TABLE-US-00003 Prodn. exmpl. PEx1 PEx2 PEx3 PEx4 PEx5 PEx6 PEx7 PEx8 PEx9 Comp. Comp. Comp. Comp. A3 90.37 90.25 90.19 90.20 A4 90.23 89.43 89.98 A8 90.24 90.24 Additive base 5.02 5.02 5.02 5.02 5.02 5.02 5.02 5.02 5.02 mixture A7 4.00 3.99 3.99 4.90 3.99 3.99 4.30 3.99 3.99 Diethanolamine 0.30 0.35 0.35 0.30 0.30 0.35 0.30 0.30 0.30 Gel catalyst 0.30 0.40 0.40 0.35 0.50 0.45 0.40 0.45 0.45 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 POM content 58.7 58.6 59.4 58.9 58.5 58.5 59.3 0 0 PEx = production example; all amounts in parts by weight, except POM content in g/kg; gel catalyst is a mixture of 95% by weight 6-dimethylamino-1-hexanol and 5% by weight of N-[2[2-dimethylamino)ethoxy]ethyl]-N-methyl-1,3-propanediamine

[0185] Foams: Production

TABLE-US-00004 CEx1 CEx2 Ex1 CEx3 CEx4 Ex2 Ex3 Ex4 Index 90 90 90 70 70 70 70 90 Polyol PEx1 PEx2 PEx4 PEx5 PEx6 PEx7 PEx8 PEx9 formulation Isocyanate CPp2 CPp2 Pp1 CPp2 CPp2 Pp1 Pp1 Pp1 Grams of 66.3 66.5 65.6 51.6 51.8 50.8 49.9 64.1 isocyanate per 100 g of polyol formulation (parts by wt.) POM content 46.4 46.3 44.1 48.1 48.1 46.5 7.2 8.4 in system (g/kg) Cream time 12 13 12 12 12 10 10 Fiber time 85 73 75 67 78 76 78 78 Rise time 95 115 100 100 105 90 78 Comment Undergoes No lid sagging raising Cell fine intermediate fine- intermediate intermediate intermediate structure intermediate Skin good ok good ok good good CEx = comparative example

[0186] Foams: Mechanical Properties

TABLE-US-00005 CEx2 Ex1 Ex4 CEx4 Ex5 Ex3 Index 90 90 90 70 70 70 Comparative Comparative Apparent density DIN EN ISO 845 kg/m.sup.3 58.6 46.1 55.4 54.6 47.3 57.6 (2009) Compression test DIN EN ISO 3386-1 (October 2015) Force at 40% compression kPa 10 11 8 9 3 4 (CV40) Damping 0.34 0.35 0.29 0.27 0.32 0.23 Compression set according to DIN EN 21% 20% 55% 15% ISO 1856-2008 22 hours at 70 C. and 75% compression Air permeability according to ASTM D dm.sup.3/s 0.25 0.14 0.14 0.40 0.22 0.34 3574 (2017) at 125 Pa differential pressure

[0187] It is apparent that the inventive foam based on the POM-containing polyether A2 has a more advantageous apparent density and, at an index of 70, compression set.

[0188] Results of emissions test according to thermodesorption method DIN EN ISO/IEC 17025:2011-10 (VDA278)

[0189] VOC: 90 C., retention time window up to n-pentacosane (C25): 48.40 min

[0190] Index 70 foams, amounts in mg/kg toluene equivalent

TABLE-US-00006 Polyol Isocyanate A B C D E F Total PEx5 CPp 2 Comparative 18 1 4 1 5 29 PEx7 Ppl 6 5 8 19

[0191] VOC evaluation according to mass library: A represents dipropylene glycol and oligomers of propylene glycol; B represents methyldioxolane, C represents cyclic propylene carbonate, D represents tetradecane, E represents dimethylaminocyclohexanol, F represents other volatile organic compounds.

[0192] It is apparent that foams based on polyether A2 exhibit markedly better emissions.

[0193] Foams produced with index of 90, amounts in mg/kg toluene equivalent

TABLE-US-00007 Polyol Isocyanate A B C F Total PEx1 CPp 2 Comparative 1 4 6 11 PEx3 Pp1 8 8

[0194] Evaluation according to mass library: A represents dipropylene glycol and oligomers of propylene glycol; B represents methyldioxolane, C represents cyclic propylene carbonate, F represents other volatile organic compounds.

[0195] It is apparent that foams produced with a higher index exhibit markedly better emissions. It is apparent that foams based on polyether A2 exhibit markedly better emissions.

[0196] FOG: 120 C., retention time window tetradecane (C14): 11 mindotricontane (C32) 41.65 min

[0197] Foams produced with index of 90, amounts in mg/kg hexadecane equivalent

TABLE-US-00008 Polyol Isocyanate A G F Total PEx1 CPp2 Comparative 6 6 PEx3 Pp1 2 2

[0198] Evaluation according to mass library: A represents dipropylene glycol and oligomers of propylene glycol; B represents methyldioxolane, C represents cyclic propylene carbonate, F represents other volatile organic compounds.

[0199] It is apparent that foams produced with a higher index exhibit markedly better emissions. It is apparent that foams based on polyether A2 exhibit markedly better emissions.

[0200] Foams produced with index of 70, amounts in mg/kg hexadecane equivalent

TABLE-US-00009 Polyol Isocyanate A G F Total PEx5 CPp2 Comparative 38 2 2 42 PEx7 Pp1 23 1 1 25

[0201] Evaluation according to mass library: A represents dipropylene glycol and oligomers of propylene glycol; F represents other volatile organic compounds and G is acridine. It is apparent that foams based on polyether A2 exhibit markedly better emissions.

[0202] Emissions Test for Aldehydes (Modified Bottle Method)

[0203] Charged into a glass bottle of one liter in volume are 25 milliliters of water and 25 millilitres of a solution of 0.3 mmol/liter of dinitrophenylhydrazine (DNPH) in 3 mM phosphoric acid-acidified acetonitrile. The content of DNPH is 7.5 mol per bottle. A foam sheet having dimensions of 40*10*4 cm.sup.3 is secured freely suspended from the lid so that the foam is not in contact with the aqueous solution at the bottom of the bottle. The bottle is closed and stored in a recirculating air drying cabinet at 65 C. for 3 hours. The bottle is allowed to cool to room temperature, the foam is withdrawn and the composition of the aqueous solution is analyzed by LC-MS/MS for the hydrazones of the aldehydes recited below. For each foam quality three bottles are analyzed. For each test run a further three bottles without foam are coanalyzed. The average reference value is subtracted from the measured values. The emissions of the respective aldehydes per kilogram of foam are extrapolated on this basis. This is reported in mg of aldehyde per kg of foam.

[0204] Foams produced with index of 90, amounts in mg/kg hexadecane equivalent

TABLE-US-00010 Formaldehyde Acetaldehyde micromoles/ micromoles/ Polyol Isocyanate mg/kg kg mg/kg kg PEx1 CPp2 Comparative 7.4 247 1.2 27 PEx3 Pp1 9.5 318 0.7 15 PEx9 Pp1 1.4 47 <0.3 <7

[0205] It is apparent that foams based on the polyether A2 exhibit somewhat worse emissions of formaldehyde and markedly better emissions for acetaldehyde.

[0206] Foams produced with index of 70, amounts in mg/kg hexadecane equivalent

TABLE-US-00011 Formaldehyde Acetaldehyde micromoles/ micromoles/ Polyol Isocyanate mg/kg kg mg/kg kg PEx5 CPp2 Comparative 11.5 384 33 PEx7 Pp1 15.2 473 15 PEx8 Pp1 1.4 47 <0.3 <7

[0207] It is apparent that foams based on the polyether A2 exhibit somewhat worse emissions of formaldehyde and markedly better emissions for acetaldehyde. Flame spread according to method FMVSS302 without supporting wires

TABLE-US-00012 Polyol Isocyanate Index 70 Index 90 mean PEx5 CPp2 Comparative 1.37 1.05 1.21 mm/s PEx7 Pp1 1.11 1.18 1.15 mm/s

[0208] Comparison of the two poly ethers A1 and A2 which each contain POM blocks shows that on average the polyether having the lower OH number achieves the slightly better result. The requirements of guideline 95/28/EC in respect of horizontal burn rate are met by all types. The requirements of standard FMVSS 302 were met by all foams except comparative example CPp2/index 70.

[0209] Content of Methylenebisdiphenylamine (MDA)

[0210] Determination was carried out according to the so-called Skarping extraction method according to Certipur with 0.1 molar acetic acid. Foam from the edge region of the shaped body was cut into 0.5 g pieces. These pieces were filled into a plastic syringe. 3 cm.sup.3 of 0.1 molar acetic acid were filled into the syringe. The syringe plunger was replaced and the contents of the syringe were compressed. The liquid was collected in a glass vessel. This liquid was completely drawn up and expelled again. A total of 20 extraction cycles were performed. The solution treated with acetic acid is finally filtered and analyzed for aromatic amines by HPLC-UV. Amounts are reported in milligrams per kilogram of foam weighed out.

TABLE-US-00013 Index 70 Index 90 mean 2,4- 4,4- 2,4- 4,4- 2,4-MDA + MDA MDA MDA MDA 4,4MDA Polyol Isocyanate mg/kg mg/kg mg/kg mg/kg mg/kg PEx5 CPp2 Comparative 0.4 2.8 0.2 2.0 2.7 PEx7 Ppl 0.3 1.8 0.3 1.2 1.8 25% 36% +50% 40% 33% PEx8 Pp1 <0.2 0.6 0.2 0.4 <0.7

[0211] It is apparent that foams based on the polyether A2 have on average lower contents of aromatic amines than those based on polyol A1.