Claims
- 1. A polyurethane polyanhydride oligomer characterized in that it comprises at least one moiety represented by the following structure: ##STR7## wherein: X is: ##STR8## wherein n is 0, 1, 2, 3, or a fused ring system;
- R.sup.1 is hydrogen or an aliphatic radical;
- A and B are both CH-- in which case R.sub.2 and R.sub.3 are independently hydrogen or an aliphatic radical; or
- A and B are connected to form --C.dbd.C--
- R.sup.4 is the residue of a mono or polyisocyanate;
- R.sup.5 is an aliphatic group, aromatic group, alicyclic group or ##STR9## R.sup.6 is an aliphatic, aromatic or alicyclic group.
- 2. The oligomer of claim 1 wherein
- X is ##STR10## A and B are both --C.dbd. R.sub.1 is CH.sub.3
- R.sub.2 is Hydrogen
- R.sub.3 is Hydrogen.
- 3. The oligomer of claim 1 wherein the anhydride equivalent weight does not exceed 1000.
- 4. The oligomer of claim 3 wherein the anhydride equivalent weight does not exceed 700.
- 5. The oligomer of claim 1 wherein the number average molecular weight ranges from about 670 to about 7000.
- 6. A process for preparing a polyurethane polyanhydride oligomer comprising the steps:
- a) reacting a hydroxyl functional 2,4-dienoate ester with a polyisocyanate under conditions sufficient to react essentially all of the isocyanate groups to form a polyurethane polyene; and
- b) reacting by Diels Alder addition the unsaturated bonds of the polyurethane polyene with an unsaturated polycarboxylic acid anhydride containing material.
- 7. The process of claim 6 wherein the hydroxyl functional 2,4-dienoate ester is hydroxypropyl sorbate.
- 8. The process of claim 7 wherein the polyisocyanate is a triisocyanate.
- 9. The process of claim 8 wherein the residual isocyanate groups present after reaction of the hydroxypropyl sorbate with triisocyanate are reacted with 1,6-hexanediol.
- 10. The process of claim 6 wherein the unsaturated polycarboxylic acid anhydride containing material is maleic anhydride.
- 11. The process of claim 6 wherein the polyurethane polyanhydride is characterized in that it contains at least one moiety represented by the following structure: ##STR11## wherein: X is: ##STR12## wherein n is 0, 1, 2, 3, or a fused ring system;
- R.sup.1 is hydrogen or an aliphatic radical;
- A and B are both CH-- in which case R.sub.2 and R.sub.3 are independently hydrogen or an aliphatic radical; or
- A and B are connected to form --C.dbd.C--
- R.sup.4 is the residue of a mono or polyisocyanate;
- R.sup.5 is an aliphatic group, aromatic group, alicyclic group or ##STR13## R.sup.6 is an aliphatic, aromatic or alicyclic group.
- 12. The process of claim 6 wherein the polyurethane polyanhydride has an anhydride equivalent weight not exceeding 1000.
- 13. A method of coating a substrate comprising the steps of:
- I. coating the substrate with one or more applications of a pigmented basecoating composition to form a basecoat;
- II. coating the basecoat with one or more applications of a transparent non-yellowing topcoating composition comprising
- A. a hydroxyl functional material
- B. a polyurethane polyanhydride oligomer of claim 1.
- 14. The method of claim 13 wherein the basecoat and topcoat are allowed to dry or cure together on the substrate.
- 15. The method of claim 13 wherein the non-yellowing topcoating composition is in the form of a two package composition in which the hydroxyl functional material is separate from the polyanhydride.
Parent Case Info
This is a divisional of application Ser. No. 504,814, filed Apr. 5, 1990, now U.S. Pat. No. 5,059,655.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4772666 |
Just et al. |
Sep 1988 |
|
4826921 |
Andrews et al. |
May 1989 |
|
Divisions (1)
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Number |
Date |
Country |
Parent |
504814 |
Apr 1990 |
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