Method and apparatus for the production of essentially void free foams

• US 5,801,210 A
• Filed: 10/29/1997
• Issued: 09/01/1998
• Est. Priority Date: 10/29/1997
• Status: Expired due to Term

• Current Assignee: Bayer Materialscience LLC (Covestro AG)
• Original Assignee: Bayer Corporation (Bayer AG)
• Inventors: Radovich, David A., Steppan, David D., Spitler, Keith G., Shoup, James D.
• Primary Examiner(s): Foelak, Morton
• Application Number:
  US08/960,493
• Time in Patent Office: 307 Days
• Field of Search: 521/155, 521/130, 264/50, 264/53
• US Class Current: 521/130
• CPC Class Codes: B29C 44/3446 Feeding the blowing agent
• CPC Class Codes: B29C 44/348 by regulating the temperature and/or the pressure, e.g. suppression of foaming until the pressure is rapidly decreased
• CPC Class Codes: C08G 18/0895 Manufacture of polymers by continuous processes C08G18/0838 takes precedence
• CPC Class Codes: C08G 2110/0008 flexible
• CPC Class Codes: C08G 2110/005 < 50kg/m3
• CPC Class Codes: C08J 2375/04 Polyurethanes
• CPC Class Codes: C08J 9/122 Hydrogen, oxygen, CO2, nitrogen or noble gases

Abstract

A process for the manufacture of polyurethane foam comprising the steps of (i) mixing at a reaction index of 40 to 400: (a) a polyisocyanate blend comprising at least one polyisocyanate and optionally, additives and fillers; (b) a polyol blend comprising isocyanate reactive components and optionally, water, additional blowing agents, catalysts, surfactants, fillers and other additives; wherein either or both said polyisocyanate blend or said polyol blend contain between 0.3 to about 20 wt. % CO₂ based on the total weight of said polyisocyanate blend and said polyol blend; (ii) introducing and uniformly mixing in liquid form of CO₂ as a blowing agent into either or both said polyisocyanate blend or said polyol blend and maintaining said CO₂ in said liquid form. The present invention also relates to an apparatus, which performs the above-mentioned process.

Claims

1. A process for the manufacture of polyurethane foam comprising the steps of

(i) mixing at a reaction index of 40 to 400:

(a) a polyisocyanate blend comprising at least one polyisocyanate and optionally, additives and fillers; and

(b) a polyol blend comprising isocyanate reactive components and optionally, water, additional blowing agents, catalysts, surfactants, fillers and other additives;

wherein either or both said polyisocyanate blend or said polyol blend contain between 0.3 to about 20 wt % of liquid CO₂ based on the total weight of said polyisocyanate blend and said polyol blend; and

(ii) introducing and uniformly mixing in liquid form CO₂ as a blowing agent into either or both said polyisocyanate blend or said polyol blend and maintaining said CO₂ in said liquid form under pressure, wherein either said polyol blend or said polyisocyanate blend is mixed with a corresponding different polyisocyanate blend or a polyol blend, respectively, through an impingement mixhead; and

(iii) dispensing said reaction mixture into a zone of lower pressure.

2. The process according to claim 1 wherein said polyol blend contains between 0.5 to about 10 wt. % of CO₂ based on the total weight of said polyisocyanate blend and said polyol blend.

3. The process according to claim 1 wherein said CO₂ is mixed with a static mixer with either or both said polyisocyanate blend or said polyol blend.

4. The process according to claim 3 wherein either said polyol blend or said polyisocyanate blend or both are introduced into a day tank having a pressure ranging from 800 to 1400 psi and a temperature ranging from 65°

-100°

F.

5. The process according to claim 4 wherein either said polyol blend or said polyisocyanate blend mixed with said liquid CO₂ in said static mixer is recycled through said day tank and said static mixer until said polyol blend or said polyisocyanate blend mixed with said liquid CO₂ forms a homogeneous mixture.