Low density polyurethane foam, method of producing, and articles comprising the same

• US 7,338,983 B2
• Filed: 08/09/2005
• Issued: 03/04/2008
• Est. Priority Date: 02/10/2004
• Status: Active Grant

• Current Assignee: World Properties Incorporated
• Original Assignee: World Properties Incorporated
• Inventors: Sato, Tadashi, Simpson, Scott S.
• Primary Examiner(s): COONEY, JOHN M
• Application Number:
  US11/200,536
• Publication Number:
  US 20060025493A1
• Time in Patent Office: 938 Days
• Field of Search: 521/124, 521/125, 521/130, 521/131, 521/170, 521/174, 521/176, 428/304.4, 428/423.1
• US Class Current: 521/170
• CPC Class Codes: C08G 18/4837 and other oxyalkylene units
• CPC Class Codes: C08G 18/6674 with compounds of group C08G18/3203
• CPC Class Codes: C08G 2110/0008 flexible
• CPC Class Codes: C08G 2190/00 Compositions for sealing or packing joints
• CPC Class Codes: C08J 2375/04 Polyurethanes
• CPC Class Codes: C08J 9/141 Hydrocarbons
• CPC Class Codes: C08J 9/143 Halogen containing compounds
• CPC Class Codes: C08J 9/146 only fluorine as halogen atoms
• CPC Class Codes: C09K 3/1021 Polyurethanes or derivatives thereof
• CPC Class Codes: F16J 15/102 characterised by material
• CPC Class Codes: F16J 15/108 Special methods for making a non-metallic packing
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]
• CPC Class Codes: Y10T 428/31551 Of polyamidoester [polyurethane, polyisocyanate, polycarbamate, etc.]

Abstract

A method for producing a cured, low-density polyurethane foam, the method comprises frothing a reactive polyurethane-forming composition comprising an isocyanate-containing component, an active hydrogen-containing component reactive with the isocyanate-containing component, a blowing agent, a surfactant, and catalyst system, wherein the catalyst system provides for a delayed curing of the foam; casting the frothed reactive polyurethane-forming composition onto a first carrier; placing a second carrier on a side of the cast foam opposite the first carrier; blowing the froth with the second carrier in place; and curing the blown froth so as to provide a polyurethane foam layer having a density of about 50 to about 400 kg/m³ and a thickness of about 0.3 to about 13 mm. The foams are useful as sealing members.

Claims

1. A method for producing a cured, low density polyurethane foam, the method comprising:

mechanically frothing a reactive polyurethane-forming composition comprising an isocyanate-containing component, an active hydrogen-containing component reactive with the isocyanate-containing component, a blowing agent comprising water, a surfactant, and catalyst system, wherein the catalyst system provides for a delayed curing of the foam; and

in a continuous process,

casting the frothed reactive polyurethane-forming composition onto a moving first carrier;

placing a second carrier on a side of the cast froth opposite the first carrier;

blowing the froth with the second carrier in place; and

curing the blown froth so as to provide a polyurethane foam layer having a compression load deflection at 50% of about 0.003 to about 0.025 MPa, a compression load deflection at 75% of about 0.02 to about 0.40 MPa, a density of about 50 to about 400 kg/m³ and a thickness of about 0.3 to about 13 mm.

2. The method of claim 1, wherein the second carrier imparts a smooth surface finish to the cured polyurethane foam.

3. The method of claim 1, further comprising passing the first carrier, froth, and second carrier through a thickness adjusting means.

4. The method of claim 1, wherein the first carrier, the second carrier, or both are bonded to the cured polyurethane foam layer.

5. The method of claim 4, wherein the bonding occurs upon cure of the blown froth while in contact with the first carrier, second carrier, or both.

6. The method of claim 1, wherein the first carrier, the second carrier, or both comprises a layer that is releasable from the first carrier, the second carrier, or both, but that bonds to the frothed, blown reactive polyurethane foam layer upon cure;

and further comprising removing the first carrier, second carrier or both from the cured polyurethane foam and the bonded releasable layer.

7. The method of claim 1, wherein the active hydrogen-containing component comprises a polyether polyol.

8. The method of claim 7, wherein the polyether polyol has the formula R[(OCH_nH_2n)_zOH]_a, wherein R is hydrogen or a polyvalent hydrocarbon radical;

a is 2-8, equal to the valence of R;

n in each occurrence is 1-2; and

z in each occurrence is 2 to about 200.

9. The method of claim 8, wherein the polyether polyol has an ethylene oxide content of about 20 wt. % or less, based on the weight of the polyol.

10. The method of claim 1, further comprising a chemical blowing agent, a physical blowing agent, or a combination thereof, in addition to water.

11. The method of claim 10, wherein the physical blowing agent is 1,1-dichloro-1-fluoroethane, 1,1-dichloro-2,2,2-trifluoro-ethane, monochlorodifluoromethane, 1-chloro-1,1-difluoroethane;

1,1,1,3,3,3-hexafluoropropane, 2,2,4,4-tetrafluorobutane, 1,1,1,3,3,3-hexafluoro-2-methylpropane, 1,1,1,3,3-pentafluoropropane, 1,1,1,2,2-pentafluoropropane, 1,1,1,2,3-pentafluoropropane, 1,1,2,3,3-pentafluoropropane, 1,1,2,2,3-pentafluoropropane, 1,1,1,3,3,4-hexafluorobutane, 1,1,1,3,3-pentafluorobutane, 1,1,1,4,4,4-hexafluorobutane, 1,1,1,4,4-pentafluorobutane, 1,1,2,2,3,3-hexafluoropropane, 1,1,1,2,3,3-hexafluoropropane, 1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, pentafluoroethane, methyl-1,1,1-trifluoroethylether, difluoromethyl-1,1,1-trifluoroethylether;

n-pentane, isopentane, cyclopentane, or a combination comprising at least one of the foregoing blowing agents.

12. The method of claim 1, wherein the catalyst comprises a metal acetylacetonate.

13. The method of claim 1, wherein the cured polyurethane foam layer includes cells having average cell diameters of about 20 to about 500 micrometer.

14. The method of claim 1, wherein the relative dielectric constant of the cured polyurethane foam layer at each of the frequencies of 10 kHz, 100 kHz and 1 MHz is about 1 to about 2.0.

15. The method of claim 1, wherein the foam has a thickness of 0.3 to 5 mm and a density of about 320 to about 400 kg/m³.

16. The method of claim 1, wherein the foam has a thickness of about 0.5 to about 13 mm and a density of about 50 to about 240 kg/m³.

17. An article comprising the foam of claim 1.

18. The article of claim 17, in the form of a sealing member.

19. The method of claim 1, wherein one or both of the first carrier and the second carrier comprises a release layer on at least one side thereof, and the frothed reactive polyurethane-forming composition is contacted with one or both of the release layers on the first and second carriers.