Claims
- 1. A process of preparing a prepolymer-dianhydride adduct comprising the steps of:
- forming a solution of a prepolymer diol selected from compounds of the formula:
- R.sup.1 --(OH).sub.n
- where R.sup.1 is the residue of an organic molecule having a molecular weight from 300 to 8,000 and n is a number from 1.7 to 3.0; and a dianhydride selected from compounds of the formula: ##STR7## where R is a tetravalent organic group containing 4 to 40 carbon atoms in a highly polar comutual solvent selected from dimethyl acetamide, dimethylformamide, dimethylsulfoxide, sulfolane or N-methylpyrrolidone in which the molar ratio of dianhydride to diol is at least 5:1;
- reacting the diol and dianhydride to form an adduct of the formula: ##STR8## and recovering the adduct from the solution.
- 2. A process according to claim 1 in which the ratio of anhydride to prepolymer diol is from 10:1 to 25:1.
- 3. A process according to claim 1 in which the dianhydride is selected from tetrahydrofuran tetracarboxylic dianhydride, pyromellitic dianhydride, or benzophenone tetracarboxylic dianhydride.
- 4. A process according to claim 1 in which the molecular weight is from 400 to 5,000 and n is a number from 1.9 to 2.5.
- 5. A process according to claim 1 in which R' is selected from polyester, polyether, saturated aliphatic hydrocarbon or dimer fatty acid.
- 6. A process according to claim 1 further including the step of forming a polyester linked elastomer by reacting the separated adduct with prepolymer polyol.
- 7. A process according to claim 1 in which the solution further includes a metal acetylacetonate catalyst and the catalyst to anhydride mole ratio is from 0.001 to 0.5.
- 8. A process according to claim 7 in which the catalyst to anhydride ratio is from 0.02 to 0.2.
- 9. A process according to claim 7 in which the adduct reaction is conducted at a temperature less than 100.degree. C.
Parent Case Info
This is a continuation of application Ser. No. 761,252, filed Jan. 21, 1977, now abandoned.
ORIGIN OF THE INVENTION
The invention described herein was made in the performance of work under a NASA contract and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958, Public Law 83-568 (72 Stat. 435; 42 USC 2457).
US Referenced Citations (6)
Continuations (1)
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Number |
Date |
Country |
Parent |
761252 |
Jan 1977 |
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