MDI-based polyurethane prepolymer with low monomeric MDI content

• US 6,884,904 B2
• Filed: 04/12/2001
• Issued: 04/26/2005
• Est. Priority Date: 04/12/2001
• Status: Expired due to Term

• Current Assignee: Coim USA Inc. (C.O.I.M. SPA - Chimica Organica Industriale Milanese)
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Goddard, Richard Joseph, Paulsen, Evelyn Jennifer Lin, Smith, Andrea Karen
• Primary Examiner(s): Seaman, D. Margaret
• Assistant Examiner(s): Oh, Taylor V
• Application Number:
  US09/833,278
• Publication Number:
  US 20030009049A1
• Time in Patent Office: 1,475 Days
• Field of Search: 528/60, 528/76, 252/182.2, 428/423.1, 156/331.7, 525/63, 560/26
• US Class Current: 560/26
• CPC Class Codes: C08G 18/10 Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
• CPC Class Codes: C08G 18/7671 containing only one alkylene bisphenyl group
• CPC Class Codes: C09J 175/04 Polyurethanes

Abstract

An MDI/polypropylene polyether prepolymer composition consisting essentially of at least 80 wt % perfect prepolymers and less than 2 wt % free MDI monomer suitable for use in polyurethane adhesive compositions optionally also comprising a curative for isocyanate groups.

Claims

1. In a method for adhesively joining or sealing two substrates using a polyurethane adhesive composition comprising a polyurethane prepolymer composition and, optionally, an isocyanate-reactive curative by applying onto a substrate the polyurethane adhesive composition and contacting the adhesive composition disposed on the substrate to a second substrata such that a bond is formed, the Improvement which comprises utilizing a polyurethane prepolymer composition comprising the prepolymer reaction product of (a) 4,4′

-diphenylmethane diisocyanate (MDI) and (b) a polyol composition comprising a propylene oxide based polyether polyol and consisting essentially of at least 80 wt % perfect prepolymers and less than 2 wt % free MDI monomer.

2. The method of claim 1 in which the 4,4′

-diphenyl-methane diisocyanate comprises isomeric mixtures of MDI and/or polymeric MDI.

3. The method of claim 1 in which the 4,4′

-diphenylmethane diisocyanate comprises an isomeric mixture of MDI containing 30-98 wt % of 4,4′

isomer, 2-70 wt % of the 2,4′

isomer, and 0-5 wt % of the 2,2′

isomer (with the wt % totaling 100%); and

/or polymethylene poly(phenylisocyanate) having an average isocyanate functionality of 2.1 to 3.5, isocyanate group content of 18.0 to about 33.6, and containing about 30 to 96 wt % monomeric 4,4′

MDI, about 2-70 wt % monomeric 2,4′

MDI, and less than 5 wt % monomeric 2,2′

MDI, and from 2-60 wt % higher ring homologues of the MDI series (with the wt % totaling 100%).

4. The method of Claim 1 in which the propylene oxide based polyether polyol is a polypropylene polyether polyol with functionality of two or greater and an average equivalent weight between 100 and 3000.

5. The method of claim 1 in which the propylene oxide based polyether polyol is an ethylene oxide capped polypropylene polyether polyol.

6. The method of claim 1 in which 0 to 60 wt % of the polyol composition comprises a di- or multi-functional alkylene ether polyol, a polyester polyol, a polyester polyol from polycaprolactones or a hydroxyl terminated polybutadienes.

7. The method of claim 1 in which the polyurethane prepolymer composition consists essentially of at least 90 wt % perfect prepolymers.

8. The method of claim 1 in which the polyurethane prepolymer composition consists essentially of less than 1 wt % free MDI monomer.

9. The method of claim 1 in which the polyurethane prepolymer composition comprises a free prepolymer NCO functionality ranging from 0.2 to 15 wt %.

10. The method of claim 1 in which the polyurethane polyol composition has an average Mn ranging from about 400 to 16,000.

11. In a method for adhesively joining or sealing two substrates using a polyurethane adhesive composition comprising a polyurethane prepolymer composition and, optionally, an isocyanate-reactive curative by applying onto a substrate the polyurethane adhesive composition and contacting the adhesive composition disposed on the substrate to a second substrate such that a bond is formed, the improvement which comprises utilizing a polyurethane prepolymer composition comprising the reaction product of (a) 4,4′

-diphenyl-methane diisocyanate with a polyol composition comprising a polypropylene polyether polyol with functionality of two or greater and an average equivalent weight between 100 and 8000 and consisting essentially of at least 90 wt % perfect prepolymers, less than 2 wt % free MDI monomer and a free prepolymer NCO functionality ranging from 0.2 to 15 wt %.

12. The method of claim 11 in which the 4,4′

-diphenyl-methane diisocyanate comprises an isomeric mixture of MDI containing 30-98 wt % of 4,4′

isomer, 2-70 wt % of the 2,4′

isomer, and 0-5 wt % of the 2,2′

Isomer (with the wt % totaling 100%); and

/or polymethylen poly(phenylisocyanate) having an average isocyanate functionality of 2.1 to 3.5, isocyanate group content of 18.0 to about 33.6, and containing about 30 to 96 wt % monomeric 4,4′

MDI, about 2-70 wt % monomeric 2,4′

MDI, and less than 5 wt % monomeric 2.2′

MDI, and from 2-60 wt % higher ring homologues of the MDI series (with the wt % totaling 100%).

13. The method of claim 11 in which the propylene, oxide based polyether polyol is an ethylene oxide capped polypropylene polyether polyol.

14. The method of claim 11 in which 0 to 60 wt % of the polyol composition comprises a di or multi-functional alkylene ether polyol, a polyester polyol, a polyester polyol from polycarbonate or a hydroxyl terminated polybutadiene.

15. The method of claim 14 in which the polyurethane prepolymer composition consists essentially of less than 0.5 wt % free MDI monomer and contains a free prepolymer NCO functionality ranging from 0.5 to 8 wt %.

16. The method of claim 15 in which the polyol composition has an average Mn ranging from about 400 to 16,000.