STORAGE STABLE HFO- OR HCFO-CONTAINING POLYOL COMPOSITIONS FOR MAKING FLAME-RESISTANT RIGID POLYURETHANE FOAMS

Abstract

Formulated polyol compositions include a non-halogenated polyol, a halogenated polyol, a phosphorus-containing flame retardant, an HFO and/or HCFO blowing agent and certain urethane catalysts. The compositions exhibit excellent storage stability. Foams made from the formulated polyol compositions have unexpectedly improved fire performance, as indicated by certain fire tests.

Claims

1. A formulated polyol composition comprising: a) at least one non-halogenated polyol having a hydroxyl functionality of 2 to 8 and a hydroxyl number of 200 to 500; b) at least one brominated polyol; c) at least one phosphorus-containing flame retardant; d) at least one HFO and/or HCFO blowing agent; e) at least one foam-stabilizing surfactant and f) a urethane catalyst selected from one or more of i) a dialkylimidazole compound ii) 2,2′-dimorpholinodiethylether iii) a tetraalkyl guanidine compound iv) 2,2,2-dimethylaminoethoxyethyl methylaminoethanol and v) N,N-dimethylcyclohexylamine.

2. The formulated polyol composition of claim 1 wherein the urethane catalyst includes at least one dialkylimidazole compound.

3. The formulated polyol composition of claim 2 wherein the urethane catalyst further includes one or more of 2,2′-dimorpholinodiethylether, a tetraalkyl guanidine compound, 2,2,2-dimethylaminoethoxyethyl methylaminoethanol and N,N-dimethylcyclohexylamine.

4. The formulated polyol composition of claim 1 wherein the catalyst is a mixture of a dialkylimidazole compound, 2,2-dimorpholinodiethylether and optionally N,N-dimethylcyclohexylamine.

5. The formulated polyol composition of claim 1 wherein the catalyst is a mixture of a dialkylimidazole compound and a tetraalkyl guanidine compound.

6. The formulated polyol composition of claim 1 wherein the catalyst is a mixture of a dialkylimidazole compound, a tetraalkyl guanidine compound and 2,2,2-dimethylaminoethoxyethyl methylaminoethanol.

7. The formulated polyol composition of claim 1 wherein the brominated polyol has a hydroxyl number of 50 to 400, contains 2 to 8 hydroxyl groups and contains 1 to 4 bromine atoms.

8. The formulated polyol composition of claim 1 wherein the HCFO and/or HCFO is one or more selected from the group consisting of trifluoropropene, 1,3,3,3-tetrafluoropropene, 1,1,3,3-tetrafluoropropene, 2,2,3,3-tetrafluoropropene, 1,2,3,3,3-pentafluoropropene, 1,1,1-trifluoropropene, 1,1,1,3,3-pentafluoropropene, 1,1,2,3,3-pentafluoropropene, (Z)-1,1,1,2,3-pentafluoropropene, 1-chloro-3,3,3-trifluoropropene and 1,1,1,4,4,4-hexafluorobut-2-ene.

9. The formulated polyol composition of claim 1 which optionally further contains h) at least one non-halogenated isocyanate-reactive material different from components a)-f), wherein component a) constitutes 40 to 75% of the combined weights of components a)-f) and h), component b) constitutes 4 to 15% of the combined weights of components a)-f) and h), component c) constitutes 5 to 25% of the combined weights of components a)-f) and h) and component d) constitutes 5 to 30% of the combined weights of components a)-f) and h).

10. A method of making a rigid polyurethane foam, comprising the steps of: I. forming a reaction mixture comprising a) at least one non-halogenated polyol having a hydroxyl functionality of 2 to 8 and a hydroxyl number of 200 to 560; b) at least one brominated polyol; c) at least phosphorus-containing flame retardant; d) a physical blowing agent that includes at least one HFO and/or HCFO blowing agent; e) at least one foam-stabilizing surfactant and f) a urethane catalyst selected from one or more of i) a dialkylimidazole compound ii) 2,2′-dimorpholinodiethylether iii) a tetraalkyl guanidine compound iv) 2,2,2-dimethylaminoethoxyethyl methylaminoethanol and v) N,N-dimethylcyclohexylamine; and g) at least one aromatic polyisocyanate, and II. curing the reaction mixture under conditions that the physical blowing agent volatilizes and components a), b) and g) react to form the rigid polyurethane foam.

11. The method of claim 10 wherein the urethane catalyst includes at least one dialkylimidazole compound.

12. The method of claim 11 wherein the urethane catalyst further includes one or more of 2,2′-dimorpholinodiethylether, a tetraalkyl guanidine compound, 2,2,2-dimethylaminoethoxyethyl methylaminoethanol and N,N-dimethylcyclohexylamine.

13. The method of claim 10 wherein the catalyst is a mixture of a dialkylimidazole compound, 2,2-dimorpholinodiethylether and optionally N,N-dimethylcyclohexylamine.

14. The method of claim 10 wherein the catalyst is a mixture of a dialkylimidazole compound and a tetraalkyl guanidine compound.

15. The method of claim 10 wherein the catalyst is a mixture of a dialkylimidazole compound, a tetraalkyl guanidine compound and 2,2,2-dimethylaminoethoxyethyl methylaminoethanol.

Description

EXAMPLES 1-4 AND COMPARATIVE SAMPLES A-B

[0073] Formulated polyol compositions are made by combining the ingredients listed in Table 1.

[0074] Polyol A is a polyether polyol having a hydroxyl functionality of 4.5 and a hydroxyl number of 490.

[0075] Polyol B is a terephthalic acid/diethylene glycol/ethylene glycol/glycerin polyester polyol having an average hydroxyl functionality of 2.4 and a hydroxyl number of 315.

[0076] Halogenated Polyol is a polyester diol based on tetrabromophthalic acid having a hydroxyl number of 220.

[0077] LBA is Solstice® LBA, trans-1-chloro-3,3,3-trifluoropropene.

[0078] Catalyst A is a mixture of 70% 1,2-dimethylimidazole and 30% ethylene glycol.

[0079] Catalyst B is 2,2-dimorpholinoether (DMDEE).

[0080] Catalyst C is a mixture of tetraethyl guanidine and 2,2,2-dimethylaminoethoxyethyl methylaminoethanol.

[0081] Catalyst D is dimethylcyclohexylamine.

[0082] Catalyst E is a mixture of 70% bis(N,N-dimethylaminoethy)ether and 30% dipropylene glycol.

[0083] Catalyst F is dimethylbenzyl amine.

TABLE-US-00001 TABLE 1 Parts By Weight Comp. Comp. Ingredient A* B* Ex. 1 Ex. 2 Ex. 3 Ex. 4 Polyol A 25.17 25.17 26.63 26.63 26.63 26.63 Polyol B 34.52 34.52 34.52 34.52 34.52 34.52 Halogenated 10.7 10.7 10.7 10.7 10.7 10.7 Polyol Triethyl 5.0 5.0 5.0 5.0 5.0 5.0 Phosphate Trichloropropyl 10.0 10.5 10.0 10.0 10.0 10.0 Phosphate HFC 245a 3.0 0 0 0 0 0 HFC 365/227 5.0 0 0 0 0 0 (93:7) LBA 0 7.5 7.0 7.0 7.0 7.0 Water 2.8 2.8 2.8 2.8 2.8 2.8 Silicone 2.96 2.96 2.5 2.5 2.5 2.5 Surfactant Catalyst A 0 0 0.6 0.6 0.35 0.15 Catalyst B 0 0 0 0.25 0.45 0.4 Catalyst C 0 0 0.25 0 0 0 Catalyst D 0 0 0 0 0 0.15 Catalyst E 0.25 0.25 0 0 0 0 Catalyst F 0.6 0.6 0 0 0 0

[0084] Each of the formulated polyol compositions is evaluated twice by reacting it with a polyisocyanate to produce a foam, once immediately upon being prepared and once after a portion of the composition is stored at 40° C. for 28 days. The polyisocyanate is a polymeric MDI having an average isocyanate functionality of 2.7 and an isocyanate content of 31.1%. The weight ratio of the polyisocyanate to the formulated polyol composition is 1.23 in all cases.

[0085] The foam is made by separately bringing the polyisocyanate and formulated polyol composition to 20-22° C. and then mixing them using a high speed laboratory mixer to form a homogeneous reaction mixture. The reaction mixture is poured into a 20 cm×20 cm box and allowed to rise freely and cure. The foam is cut into test specimens after one hour.

[0086] Gel time is evaluated by touching the surface of the curing reaction mixture periodically with a metal stick. The gel time is the time after the polyisocyanate and formulated polyol composition are mixed at which strings no longer form when the metal stick is pulled away. Free rise foam density is measured according to ASTM D 6226. Open cell content is measured according to ASTM D 1622. The foams are evaluated according to DIN 4102 and the flame height measured. In addition, the friability of the foams made after aging the formulated polyol compositions for 28 days is evaluated subjectively. Results are as indicated in Table 2.

TABLE-US-00002 TABLE 2 Comp. Comp. A* B* Ex. 1 Ex. 2 Ex. 3 Ex. 4 0 days aging results Gel time, s 149 155 100 132 155 135 Foam Density, 33.2 33.4 32.1 32.8 30.5 29.2 kg/m.sup.3 Open Cell 14 N.D. N.D. N.D. 11 13 Content, % Flame height, 125 115 85 85 80 75 mm 28 days aging results Gel time, s 160 200 102 170 159 143 % increase.sup.1 7% 29% 2% 29% 2.5% 6% Foam Density, 34.0 33.9 32.9 33.2 30.9 29.9 kg/m.sup.3 Open Cell N.D. N.D. N.D. N.D. 12 14 Content, % Flame height, 130 150 95 95 85 85 mm *Not an example of the invention. .sup.1% increase in gel time after aging the formulated polyol composition for 28 days prior to foaming.

[0087] Comparative Sample A is a baseline case in which the blowing agent is a mixture of HFC 245a, HFC 365 and HFC 227 and a conventional amine catalyst package is used. The gel time prior to aging the formulated polyol composition is 149 seconds; this increases 7% when the polyol composition is aged before foaming. The foam is brittle. The flame height on the DIN 4102 test is 125 mm on foams made prior to aging the formulated polyol composition; this rises slightly to 130 mm on foams made after the aging step.

[0088] Comparative Sample B shows the effect of substituting an HFCO blowing agent into the formulation of Comparative Sample A. Pre-aging values for gel time, free rise density, open cell count and flame height are quite similar to those of Comparative Sample A. However, foams made after the formulated polyol compositions are aged demonstrate large increases in gel time. These gel time increases are clear indications of storage instability. In addition, the foams become very brittle. Comparative Sample B exhibits a large increase in flame height when the polyol has been aged prior to foaming.

[0089] Examples 1-4 show the effect of the selection of various catalyst mixtures that all include a dialkylimidazole catalyst.

[0090] Foam made from formulated polyol composition Example 1 shows almost no change in gel time when made after the polyol composition has been aged for 28 days. This indicates exceptionally good storage stability. Aging the polyol composition does not alter any other foam properties in any significant way.

[0091] A 29% increase in gel time is seen in foams made after the formulated polyol composition of Example 2 has been aged 28 days. However, no foam brittleness is seen.

[0092] Examples 1 and 2 are somewhat more reactive than Comparative Samples A and B. In Example 3, the amounts of catalysts are adjusted to bring the gel time of the unaged case into line with Comparative Samples A and B. Only a 2.5% difference in gel time is seen between the unaged and aged cases, the open cell count remains low and only slight brittleness is seen.

[0093] Example 4 is similar to Examples 1 and 3 in that aging the polyol composition leads to only a small increase in gel time, and density and open cell count are virtually unaffected.

[0094] The performance of the foams of the DIN 4102 flame test is significant and unexpected. Comparative Samples A and exhibit flame heights that range from 115 to 125 mm for forms made from unaged polyol compositions, and from 130 to 150 mm on foams made from the aged polyol compositions. Foams made from unaged polyol composition Examples 1-4 all exhibit flame heights of only 75 to 85 mm. This is a reduction of approximately 25 to 40%. Only small increases in flame height are seen in the foams made from the aged polyol compositions. Compared to Comparative Samples A and B, Examples 1-4 when made with the aged polyol compositions show reductions in flame height of about 20 to 60%.