POLYURETHANE INSULATING FOAMS AND PRODUCTION THEREOF

Abstract

A process is described for producing PU foams, especially rigid PU foams, based on foamable reaction mixtures containing polyisocyanates, compounds having reactive hydrogen atoms, blowing agents, foam stabilizers, and possibly further additives, wherein specific perfluoropolyethers are additionally used.

Claims

1-14. (canceled)

15. A composition for the production of rigid polyurethane foam, comprising an isocyanate component, a polyol component, and at least one perfluoropolyether comprising a linear structure of formula (a): ##STR00011## wherein for formula (a): a=1 to 5; R.sub.1 and R.sub.5 are, independently of one another, —CF.sub.3, —C.sub.2F.sub.5, —C.sub.3F.sub.7, —C.sub.4F.sub.9, —CF.sub.2H, —C.sub.2F.sub.4H, —C.sub.3F.sub.6H or C.sub.4F.sub.8H, wherein the radicals having 3 or 4 carbon atoms may be linear or branched; R.sub.2, R.sub.3, R.sub.4 independently of one another are —F or —CF.sub.3; and/or a cyclic structure of formula (b): ##STR00012## wherein for formula (b), a=1 to 4, and R.sub.2, R.sub.3, R.sub.4 are as defined in formula (a); and wherein the composition optionally also comprises: a catalyst that catayses the formation of a urethane or isocyanurate bond; a blowing agent; and/or a foam stabilizer.

16. The composition of claim 15, wherein R.sub.1 and R.sub.5 are independently of one another —CF.sub.3, —C.sub.2F.sub.5, or —CF.sub.2H.

17. The composition of claim 15, wherein, when a=1, all radicals R.sub.2, R.sub.3 and R.sub.4═—F, or one of the radicals R.sub.2, R.sub.3, R.sub.4 is —CF.sub.3 and the two other radicals are —F.

18. The composition of claim 15, wherein for formula (b), a=1.

19. The composition of claim 15, wherein for formula (b), a=2.

20. The composition of claim 16, wherein, when a=1, all radicals R.sub.2, R.sub.3 and R.sub.4═—F, or one of the radicals R.sub.2, R.sub.3, R.sub.4 is —CF.sub.3 and the two other radicals are —F.

21. The composition of claim 20, wherein for formula (b), a=1.

22. The composition of claim 20, wherein for formula (b), a=2.

23. The composition of claim 15, wherein the linear structures of formula (a) comprise at least one structure selected from group (i) to (vii) as follows: (structure i): 1,1,1,2,3,3-hexafluoro-2,3-bis(pentafluoroethoxy)propane: ##STR00013## (structure ii): 1,1,1,2,3,3-hexafluoro-3-(pentafluoroethoxy)-2-(trifluoromethoxy)propane: ##STR00014## (structure iii): 1,1,1,2,3,3-hexafluoro-2-(pentafluoroethoxy)-3-(trifluoromethoxy)propane: ##STR00015## (structure iv): 2-(difluoromethoxy)-1,1,1,2,3,3-hexafluoro-3-(pentafluoroethoxy)propane: ##STR00016## (structure v): 1-(difluoromethoxy)-1,1,2,3,3,3-hexafluoro-2-(pentafluoroethoxy)propane: ##STR00017## (structure vi): 1,1,1,2,3,3-hexafluoro-3-{[1,1,1,2,3,3-hexafluoro (trifluoromethoxy)propan-2-yl]oxy}-2-(trifluoromethoxy)propane: ##STR00018## (structure vii): 1,1,1,3,3,4,6,6,7,9,9,10,12,12,12-pentadecafluoro-4,7,10-tris(trifluoro methyl)-2,5,8,11-tetraoxadodecane: ##STR00019##

24. The composition of claim 23, wherein the linear structures of formula (a) comprise at least two structures selected from groups (i) to (vii).

25. The composition of claim 23, wherein the linear structures of formula (a) comprise at least six structures selected from groups (i) to (vii).

26. The composition of claim 15, comprising as a cyclic structure of formula (b), 2,2,3,5,5,6-hexafluoro-3,6-bis(trifluoromethyl)-1,4-dioxane: ##STR00020##

27. The composition of claim 15, wherein both linear structures of formula (a) and cyclic structures of formula (b) are present.

28. The composition of claim 15, wherein the perfluoropolyethers comprise at least 25% by weight of the total perfluoropolyethers present.

29. The composition of claim 15, wherein the perfluoropolyethers used, are present in a total amount of 0.01 to 15 parts per 100 parts of polyol.

30. A process for producing PU foams, based on foamable reaction mixtures containing polyisocyanates, compounds having reactive hydrogen atoms, blowing agents, foam stabilizers, and optionally further additives, wherein the perfluoropolyethers of claim 15 are additionally used.

31. A mixture suitable for the production of a rigid PU foam, comprising the perfluoropolyethers of claim 15 and at least one blowing agent selected from a hydrocarbon having 3, 4 or 5 carbon atoms.

32. The mixture of claim 31, wherein the hydrocarbon is an oxygen-containing hydrocarbon or a chlorinated hydrocarbon.

33. The mixture of claim 31, comprising at least 26% by weight of the perfluoropolyethers.

34. The mixture of claim 31, wherein the perfluoropolyethers, taken as a whole, are present in a total amount of 0.1% to 50% by weight.

Description

EXAMPLES

Example 1: Rigid PU Foam

[0081] The following foam formulation was used for the performance comparison:

TABLE-US-00002 Proportion Component by weight Polyol* 97.0 POLYCAT ® 5** 0.5 POLYCAT ® 8** 1.0 POLYCAT ® 41** 0.4 DABCO ® TMR 2** 0.8 BDMA** 1.2 Polyether siloxane*** 3 HFC-245fa 5.5 Cyclopentane 11.5 Perfluoropolyethers according to the invention**** 2.0 MDI***** 140.4 *Polyether polyol based on sucrose, sorbitol, o-TDA and glycerol **Catalysts from Evonik Industries AG ***TEGOSTAB ® B 84813 from Evonik Industries AG ****Perfluoropolyethers having structures (i), (ii) and (iii) *****Polymeric MDI, 200 mPa*s, 31.5% NCO, functionality 2.7.

[0082] The comparative foamings were carried out by hand mixing. For this purpose, polyol, catalysts, water, foam stabilizer, perfluoropolyether and blowing agent were weighed into a beaker and mixed by means of a disc stirrer (diameter 6 cm) at 1000 rpm for 30 s. The blowing agent quantity which had evaporated during the mixing operation was determined by reweighing and replenished. The MDI was now added, the reaction mixture was stirred with the stirrer described at 3000 rpm for 7 s and immediately transferred into an aluminium mould thermostatted to 45° C. and having a size of 145 cm×14 cm×3.5 cm, the mould being inclined at an angle of 10° (along the 145 cm long side) and lined with polyethylene film. The foam formulation was in this case introduced at the lower side, so that the expanding foam fills the mould in the feed region and rises in the direction of the higher side. The amount of foam formulation used was calculated such that it was 10% above the amount necessary for minimum filling of the mould.

[0083] After 10 min, the foams were demoulded. One day after foaming, the foams were analysed. Surface and internal defects were assessed subjectively on a scale from 1 to 10, where 10 represents an (idealized) impeccable foam and 1 represents a very significantly defective foam. The thermal conductivity coefficient (A value in mW/m.Math.K) was measured on 2.5 cm-thick discs with a device of the Hesto Lambda Control type, model HLC X206, at an average temperature of 10° C. in accordance with the specifications of standard EN12667:2001.

[0084] The results are compiled in the table which follows:

TABLE-US-00003 Parts perfluoropolyether λ value in in pphp (parts per Density mW/m .Math. K hundred polyol) in kg/m.sup.3 (initial) 0 (reference) 30.0 20.9 2.0 29.9 20.1

[0085] The results show that a significant improvement in the thermal conductivity can be achieved with the perfluoropolyethers according to the invention, with the values both in the fresh and in the aged state being markedly below the reference value of the foam without addition of the perfluoropolyethers.

[0086] It should be particularly emphasized here that even a very small addition of perfluoropolyethers according to the invention leads to measurable improvements.

[0087] All other application-relevant foam properties are only insignificantly affected, if at all, by the perfluoropolyethers according to the invention. Even in the case of the quite sensitive surface quality of the foam test specimens, no changes, or only a marginal deterioration, are found.

Example 2: Rigid PIR Foam

[0088] The following foam formulation was used for the performance comparison:

TABLE-US-00004 Proportion Component by weight Polyester polyol* 100 Amine catalyst** 0.4 Potassium trimerization catalyst*** 5 Polyether siloxane**** 2 Water 0.8 Cyclopentane/isopentane 70:30 19 Flame retardant TCPP 10 Perfluoropolyethers according to the invention***** 0-4 MDI****** 220 *Stepanpol ® PS 2412 from Stepan **POLYCAT ® 5 from Evonik Industries AG ***KOSMOS ® 70 LO from Evonik Industries AG ****TEGOSTAB ® B 84504 from Evonik Industries AG *****Perfluoropolyethers having structures (i), (ii) and (iii) ******Polymeric MDI, 200 mPa*s, 31.5% NCO, functionality 2.7.

[0089] The comparative foamings were carried out by hand mixing. For this purpose, polyol, catalysts, water, foam stabilizer, flame retardant, perfluoropolyether and blowing agent were weighed into a beaker and mixed by means of a disc stirrer (diameter 6 cm) at 1000 rpm for 30 s. The blowing agent quantity which had evaporated during the mixing operation was determined by reweighing and replenished. The MDI was now added, the reaction mixture was stirred with the stirrer described at 3000 rpm for 5 s and immediately transferred into an open mould having a size of 27.5×14×14 cm (W×H×D).

[0090] After 10 min, the foams were demoulded. One day after foaming, the foams were analysed. Surface and internal defects were assessed subjectively on a scale from 1 to 10, where 10 represents an (idealized) impeccable foam and 1 represents a very significantly defective foam. The thermal conductivity coefficient (A value in mW/m.Math.K) was measured on 2.5 cm-thick discs with a device of the Hesto Lambda Control type, model HLC X206, at an average temperature of 10° C. in accordance with the specifications of standard EN12667:2001. For the determination of an ageing value for the thermal conductivity, the test specimens were stored at 70° C. over 7 days and then measured again.

[0091] The results are compiled in the table which follows:

TABLE-US-00005 Parts perfluoropolyether λ value in λ value in in pphp (parts per Density mW/m .Math. K mW/m .Math. K hundred polyol) in kg/m.sup.3 (initial) (aged) 0 (reference) 31.1 24.0 27.7 0.1 31.5 23.5 27.2 0.3 31.4 23.5 27.3 0.5 31.1 23.4 27.3 1.0 30.7 22.9 26.8 4.0 30.5 22.7 26.6

[0092] The results again show that a significant improvement in the thermal conductivity can be achieved with the perfluoropolyethers according to the invention, with the values both in the fresh and in the aged state here too being markedly below the reference value of the foam without addition of the perfluoropolyethers.

[0093] It should be particularly emphasized here that even a very small addition of perfluoropolyethers according to the invention leads to measurable improvements.

[0094] All other application-relevant foam properties are only insignificantly affected, if at all, by the perfluoropolyethers according to the invention. Even in the case of the quite sensitive surface quality of the foam test specimens, no changes, or only a marginal deterioration, are found.

Example 3: Rigid PIR Foam

[0095] The following foam formulation was used for the performance comparison:

TABLE-US-00006 Proportion Component by weight Polyester polyol* 100 Amine catalyst** 0.4 Potassium trimerization catalyst*** 5 Polyether siloxane**** 2 Water 0.8 Cyclopentane/isopentane 70:30 19 Flame retardant TCPP 10 Perfluoropolyethers according to the invention***** 0.1-4 MDI****** 220 *Stepanpol ® PS 2412 from Stepan **POLYCAT ® 5 from Evonik Industries AG ***KOSMOS ® 70 LO from Evonik Industries AG ****TEGOSTAB ® B 84504 from Evonik Industries AG *****Perfluoropolyethers having structures (i), (ii) and (iii) ******Polymeric MDI, 200 mPa*s, 31.5% NCO, functionality 2.7.

[0096] The comparative foamings were carried out by hand mixing. For this purpose, polyol, catalysts, water, foam stabilizer, flame retardant, perfluoropolyether and blowing agent were weighed into a beaker and mixed by means of a disc stirrer (diameter 6 cm) at 1000 rpm for 30 s. The blowing agent quantity which had evaporated during the mixing operation was determined by reweighing and replenished. The MDI was now added, the reaction mixture was stirred with the stirrer described at 3000 rpm for 5 s and immediately transferred into an aluminium mould thermostatted to 60° C. and having a size of 25 cm×50 cm×7 cm, the mould being lined with polyethylene film.

[0097] After 10 min, the foams were demoulded. One day after foaming, the foams were analysed. Surface and internal defects were assessed subjectively on a scale from 1 to 10, where 10 represents an (idealized) impeccable foam and 1 represents a very significantly defective foam. The thermal conductivity coefficient (λ value in mW/m.Math.K) was measured on 2.5 cm-thick discs with a device of the Hesto Lambda Control type, model HLC X206, at an average temperature of 10° C. in accordance with the specifications of standard EN12667:2001. For the determination of an ageing value for the thermal conductivity, the test specimens were stored at 70° C. over 7 days and then measured again.

[0098] The results are compiled in the table which follows:

TABLE-US-00007 Parts perfluoropolyether λ value in λ value in in pphp (parts per Density mW/m .Math. K mW/m .Math. K hundred polyol) in kg/m.sup.3 (initial) (aged) 0 (reference) 34.1 21.4 24.0 1.0 33.2 20.6 23.5 4.0 33.2 20.2 22.9

[0099] The results again show that a significant improvement in the thermal conductivity can be achieved with the perfluoropolyethers according to the invention, with the values both in the fresh and in the aged state here too being markedly below the reference value of the foam without addition of the perfluoropolyethers.

[0100] It should be particularly emphasized here that even a very small addition of perfluoropolyethers according to the invention leads to measurable improvements.

[0101] All other application-relevant foam properties are only insignificantly affected, if at all, by the perfluoropolyethers according to the invention. Even in the case of the quite sensitive surface quality of the foam test specimens, no changes, or only a marginal deterioration, are found.