Composition Suitable for Preparing Polyurethane- or Polyisocyanurate Rigid Foams

1 . A process for producing polyurethane foam by reacting at least one polyol component with an isocyanate component in the presence of a blowing agent and of one or more catalysts that catalyze the isocyanate-polyol and/or isocyanate-water reactions and/or the isocyanate trimerization, wherein the reaction is conducted in the presence of polyether-siloxane copolymer of the formula (I)

M a D b D′ c   (I)

with

R 1 =independently identical or different hydrocarbyl radicals having 1 to 16 carbon atoms or

H,

R 2 =independently R 1 or R 3 ,

R 3 polyether radicals of the general formula (II),

—R 4 O[C 2 H 4 O] d [C 3 H 6 O] e R 5   (II),

R 4 =identical or different divalent hydrocarbyl radicals which have 1 to 16 carbon atoms and may be interrupted by oxygen atoms,

CH 2 f

R 5 =independently identical or different hydrocarbyl radicals which have 1 to 16 carbon atoms and may optionally be interrupted by urethane functions, —C(O)NH—, carbonyl functions or —C(O)O—, or H, preferably methyl, —C(O)Me or H,

with

a=2,

a+b+c=10 to 200,

b/c=7 to 60,

d and e=numerical mean values which arise from the following provisos:

with the provisos

that the molar mass (numerical average M n ) of the individual polyether radicals R 3 =600 to 2000 g/mol,

that at least one R 3 radical present has a molar mass formed to an extent of 27% to 60% by mass, from —[C 3 H 6 O]— units,

that the percentage siloxane content in the polyether-siloxane copolymer is 35% to 60% by mass, by mass.

2 . The process according to claim 1 , wherein R 2 =R 3 .

3 . The process according to claim 1 , wherein the polyurethane foam is a rigid polyurethane foam.

4 . The process according to claim 1 , wherein the polyether siloxanes of the formula I are used in a total proportion by mass of 0.1 to 10 parts based on 100 parts by mass of polyol component.

5 . The process according to claim 1 , wherein at least 90 parts by weight of the polyols present, based on 100 parts by weight of polyol component, have an OH number greater than 100.

6 . The process according to claim 1 , wherein hydrocarbons having 3, 4 or 5 carbon atoms, such as, cyclo-, iso- and/or n-pentane, hydrofluorocarbons, hydrochlorofluorocarbons, hydrohaloolefins.

7 . The polyurethane foam, especially rigid polyurethane foam, obtainable by a process according to claim 1 .

8 . The polyurethane foam according to claim 7 , wherein the closed cell content is ≥80%, preferably the closed cell content being determined according to DIN ISO 4590.

9 . A thermal insulation for cooling technology comprising the polyurethane foam according to claim 7 wherein the thermal insulation is used in cooling technology selected from the group consisting of refrigerators, freezers,

an insulation panel, sandwich element,

pipe insulation,

vessel, tank walls for cryogenic storage at temperatures <−50° C.,

for insulation of vessel and/or tank walls for cold storage at temperatures of −50° C. to 20° C.,

as a constituent of cryogenic insulation systems, liquefied gas tanks or conduits, tanks or conduits for automotive gas (LPG), liquid ethylene (LEG) or liquefied natural gas (LNG).

10 . The thermal insulation according to claim 9 in the form of sprayable foam, which is applied directly to the surface to be insulated and/or filled and/or introduced into appropriate cavities.

11 . A method of lowering the thermal conductivity of polyurethane foams, especially rigid polyurethane foams, in the temperature range of −200° C. to 10° C., by using polyether-siloxane copolymer of the formula (I) in the production of the polyurethane foam, in an amount of 0.1 to 10 parts, based on 100 of parts isocyanate-reactive polyol component, where the addition can be effected before and/or during the production of the polyurethane foam.

12 . A rigid polyurethane foam made by the process of claim 1 wherein the rigid polyurethance foam has improved insulation performance within the temperature range of −200° C. to 10° C.

13 . The process according to claim 1 wherein

R 1 =methyl,

R 4 =a radical of the general formula (III)

CH 2 f   (III),

with f=1 to 8,

a+b+c=20 to 50,

b/c=15 to 50,

d and e=numerical mean values which arise from the following provisos:

with the provisos

that the molar mass (numerical average M n ) of the individual polyether radicals R 3 =800 to 1700 g/mol,

that at least one R 3 radical present has a molar mass formed to an extent of 35% to 45% by mass from —[C 3 H 6 O]— units,

that the percentage siloxane content in the polyether-siloxane copolymer is 45% to 50% by mass.

14 . The process according to claim 1 , wherein the polyether siloxanes of the formula I are used in a total proportion by mass of 1 to 3 parts, based on 100 parts by mass of polyol component.

15 . The process according to claim 1 , wherein at least 90 parts by weight of the polyols present, based on 100 parts by weight of polyol component, have an OH number greater than 200.

16 . The process according to claim 1 , wherein at least 90 parts by weight of the polyols present, based on 100 parts by weight of polyol component, have an OH number greater than 150.

17 . The process according to claim 1 , further comprising a blowing agent selected from the group consisting of n-pentane, hydrofluorocarbons, hydrochlorofluorocarbons, and hydrohaloolefins.

18 . The process according to claim 1 , further comprising a blowing agent selected from the group consisting of trans-l-chloro-3,3,3-trifluoropropene and cis-1,1,1,4,4,4-hexafluoro-2-butene.

19 . The process according to claim 1 , further comprising a blowing agent selected from the group consisting of methyl formate, acetone, dimethoxymethane, dichloromethane and 1,2-dichloroethane.

20 . The polyurethane foam according to claim 7 , wherein the closed cell content is ≥90% the closed cell content being determined according to DIN ISO 4590.