PROCESS FOR THE PREPARATION OF CLOSED CELL RIGID POLYURETHANE FOAMS

• US 20110196055A1
• Filed: 10/20/2009
• Published: 08/11/2011
• Est. Priority Date: 10/22/2008
• Status: Abandoned Application

• Current Assignee: Dow Global Technologies LLC (Dow, Inc.)
• Original Assignee: Dow Global Technologies LLC (Dow, Inc.)
• Inventors: Parenti, Vanni, Kramer, Hans
• Application Number:
  US13/122,523
• Publication Number:
  US 20110196055A1
• Time in Patent Office: Days
• US Class Current: 521/93
• CPC Class Codes: C08G 18/4018 Mixtures of compounds of group C08G18/42 with compounds of group C08G18/48
• CPC Class Codes: C08G 18/4208 containing aromatic groups
• CPC Class Codes: C08G 18/482 Mixtures of polyethers containing at least one polyether containing nitrogen
• CPC Class Codes: C08G 18/5027 directly linked to carbocyclic groups
• CPC Class Codes: C08G 18/6644 having at least three hydroxy groups
• CPC Class Codes: C08G 18/6677 having at least three hydroxy groups
• CPC Class Codes: C08G 2110/0025 rigid
• CPC Class Codes: C08G 2110/005 < 50kg/m3
• CPC Class Codes: C08G 2115/02 to isocyanurate groups
• CPC Class Codes: C08J 2205/052 Closed cells, i.e. more than 50% of the pores are closed
• CPC Class Codes: C08J 9/141 Hydrocarbons
• CPC Class Codes: C08J 9/146 only fluorine as halogen atoms

Abstract

A process for preparing a cavity-filling, fast-gelling closed cell rigid polyurethane foam comprises preparing a formulation including at least a polyisocyanate, a relatively high viscosity polyol system including at least about 10 percent by weight of an amine-initiated polyol, a physical blowing agent, a blowing catalyst and a curing catalyst, and, optionally, less than about 1.6 weight percent of water based on the polyol system. Other conventional components, such as a chain extender and/or crosslinker, surfactant, and the like may also be included. The formulation is injected under a reduced atmospheric pressure to achieve a closed cell, rigid polyurethane foam having a density of less than about 40 kg/m³, an average cell diameter of less than about 250 microns, and a thermal conductivity of less than about 19 mW/mK at 10° C. average plate temperature.

Claims

1. A process for preparing a cavity-filling closed cell rigid polyurethane foam comprising

(a) preparing a reactive foam-forming system comprising as components at least

a polyisocyanate;

a polyol system containing at least 10 percent by weight of an amine-initiated polyol and having a viscosity of at least 5,000 cP at 25°

C., according to ASTM D445;

a non-chlorofluorocarbon physical blowing agent;

a blowing catalyst;

a curing catalyst; and

, optionally,

an amount of water that is less than 1.6 percent by weight based on the polyol system;

(b)injecting the reactive foam-forming system under a reduced atmospheric pressure into a cavity, wherein the reactive foam-forming system forms a gel in no more than 25 seconds; and

(c) maintaining the reduced atmospheric pressure at least until the gel forms a closed cell rigid polyurethane foam, the foam having a density of less than about 40 kg/m³, an average cell diameter of less than 250 microns, and a thermal conductivity of less than 19 mW/mK at 10°

C. average plate temperature, according to ISO 12939/DIN 52612.

2. The process of claim 1 wherein the polyisocyanate is selected from the group consisting of 4,4′

-, 2,4′

- and 2,2′

-diphenylmethane diisocyanate and the corresponding isomer mixtures;

mixtures of 4,4′

- and 2,4′

-diphenylmethane diisocyanates;

polyphenyl-polymethylene polyisocyanates;

mixtures of 4,4′

-, 2,4′

-and 2,2′

-diphenylmethane diisocyanates; and

combinations thereof.

3. The process of claim 1 wherein the amine-initiated polyol is selected from the group consisting of mono- and dialkyl-substituted ethylenediamine;

1,2-, 1,3-, 1,4-, 1,5- and 1,6-hexamethylenediamine;

aniline;

2,3-, 2,4-, 3,4- and 2,6-tolylenediamine;

ethanolamine;

diethanolamine;

triethanolamine; and

combinations thereof.

4. The process of claim 1 wherein the non-chlorofluorocarbon physical blowing agent is selected from the group consisting of alkanes, cycloalkanes, hydrofluoroalkanes, and combinations thereof.

5. The process of claim 1 wherein the blowing catalyst is selected from the group consisting of bis-(2-dimethylaminoethyl)-ether;

pentamethyldiethylenetriamine;

triethylamine, tributyl amine, N,N-dimethylaminopropylamine, dimethylethanolamine, tetra-methylethylenediamine; and

combinations thereof.

6. The process of claim 5 wherein the blowing catalyst is selected from the group consisting of bis-(2-dimethylaminoethyl)-ether, pentamethyldiethylenetriamine;

and combinations thereof.

7. The process of claim 1 wherein the curing catalyst is selected from the group consisting of amidines;

organometallic compounds; and

combinations thereof.

8. The process of claim 7 wherein the curing catalyst is selected from the group consisting of 1,8-diazabicyclo[5.4.0]undec-7-ene;

2,3-dimethyl-3,4,5,6-tetrahydro-pyrimidine;

tin(II) and dialkyltin(IV) salts of organic carboxylic acids;

bismuth salts of organic carboxylic acids; and

combinations thereof.

9. The process of claim 1 wherein the reduced atmospheric pressure ranges from about 350 to about 850 mbar.

10. The process of claim 1 wherein the density of the rigid polyurethane foam is less than about 38 kg/m³.

11. The process of claim 10 wherein the density of the rigid polyurethane foam is less than about 36 kg/m³.

12. The process of claim 1 wherein the viscosity of the polyol system is at least about 6,000 cP at 25°

C., according to ASTM D445.

13. The process of claim 1 wherein the system gels at no more than about 20 seconds.

14. The process of claim 1 wherein the thermal conductivity at 10°

C. average plate temperature is less than about 18.5 mW/mK, according to ISO 12939/DIN 52612.

15. The process of claim 1 wherein the total amount of blowing catalyst and curing catalyst together is greater than about 1.7 percent, based on the weight of the polyol system.

17. The process of claim 1 wherein the blowing and curing catalyst is selected from the group consisting of dimethylbenzylamine, N-methyl-, N-ethyl-, and N-cyclohexylmorpholine, N,N,N′

,N′

-tetramethyl-butanediamine and -hexanediamine, bis(dimethylamino-propyl)urea, dimethylpiperazine, dimethylcyclohexylamine, 1,2-dimethyl-imidazole, 1-aza-bicyclo[3.3.0]octane, triethylenediamine, and combinations thereof.

16. A process for preparing a cavity-filling closed cell rigid polyurethane foam comprising

(a) preparing a reactive foam-forming system comprising as components at least

a polyisocyanate;

a polyol system containing at least about 10 percent by weight of an amine-initiated polyol and having a viscosity of at least about 5,000 cP at 25°

C., according to ASTM D445;

a non-chlorofluorocarbon physical blowing agent;

a blowing catalyst;

a curing catalyst; and

, optionally, an amount of water that is less than about 1.6 percent by weight based on the polyol system;

(b) injecting the reactive foam-forming system at or above atmospheric pressure into a cavity, wherein the reactive foam-forming system forms a gel in no more than about 25 seconds

(c)subjecting the cavity to a reduced atmospheric pressure; and

(d)maintaining the reduced atmospheric pressure at least until the gel forms a closed cell rigid polyurethane foam, the foam having a density of less than about 40 kg/m³, an average cell diameter of less than about 250 microns, and a thermal conductivity of less than about 19 mW/mK at 10°

C. average plate temperature, according to ISO 12939/DIN 52612.