US4065420A
Expired / Lapsed
US
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Method for making aqueous polyimide electrocoating mixtures
Assignee: General Electric Co
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Filing: 1975-12-17
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Granted: 1977-12-27
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Expires: 1995-12-17
Abstract
Abstract A method is provided for making stable electrocoatable polyimide mixtures having a high water content. A solution of polyimide in a dipolar aprotic solvent is heated in the presence of base resulting in a transitory viscosity decrease. Major amounts of water can thereafter be added to the mixture during its reduced viscosity state to produce a stable aqueous mixture.
Inventors
- 👤 John H. Lupinski
- 👤 Edith M. Boldebuck
- 👤 Wilson J. Barnes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:45
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/14; C08G73/1003; C09; C09D; C09D5/00; C09D5/44; C09D5/4419; C09D5/4461; Y; Y10; Y10S; Y10S524/00; Y10S524/901; Y10T; Y10T428/00; Y10T428/31504; Y10T428/31678; Y10T428/31681
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
215 words
A method for making an electrocoatable polyamide acid salt mixture having a high water content which comprises, 1. heating a polyimide solution of a dipolar aprotic organic solvent having at least 15% by weight of polyimide, to a temperature in the range of between about 50° C to 150° C in the presence of a base whose ionization constant in water at 25° C has a value greater than 10 -2 , until the viscosity of the resulting mixture is less than 4,000 centistokes at 25° C. 2. adding sufficient water to the resulting mixture of (1) while its viscosity is less than 4,000 centipoises at 25° C, to produce a mixture having from 5% to 40% by weight of dipolar aprotic organic solvent, 40% to 95% by weight of water and 1 to 15% by weight of solids, where the total weight of solids, water and dipolar aprotic solvent is equal to 100%, and the base is utilized in the solution of (1) at a concentration which is sufficient to neutralize any carboxy radicals of the polyimide, while providing from 0.01 to about 1 meq of base/g of polyimide having a MW sufficient to produce a viscosity of at least 1,000 centristokes at 25° C in N-methylpyrrolidone when present at 25% by weight solids.
Claim 2
Independent Claim
215 words
A method for making an electrocoatable polyamide acid salt mixture having a high water content which comprises, 1. heating a polyimide solution of a dipolar aprotic organic solvent having at least 15% by weight of polyimide, to a temperature in the range of between about 50° C to 150° C in the presence of a base whose ionization constant in water at 25° C has a value greater than 10 -2 , until the viscosity of the resulting mixture is less than 4,000 centistokes at 25° C. 2. adding sufficient water to the resulting mixture of (1) while its viscosity is less than 4,000 centipoises at 25° C, to produce a mixture having from 5% to 40% by weight of dipolar aprotic organic solvent, 40% to 95% by weight of water and 1 to 15% by weight of solids, where the total weight of solids, water and dipolar aprotic solvent is equal to 100%, and the base is utilized in the solution of (1) at a concentration which is sufficient to neutralize any carboxy radicals of the polyimide, while providing from 0.01 to about 1 meq of base/g of polyimide having a MW sufficient to produce a viscosity of at least 1,000 centristokes at 25° C in N-methylpyrrolidone when present at 25% by weight solids.
Claim 3
Dependent Claim
33 words
A method in accordance with claim 1, where the polyimide is a reaction product of trimellitic anhydride and methylenedianiline followed by the reaction of such bis(N-4-carboxyphthalimide) organo reaction product with an organic diisocyanate.
Claim 4
Dependent Claim
27 words
A method in accordance with claim 1, where the polyimide is an amino alkylene carboxylic acid modified reaction product of trimellitic anhydride, methylenedianiline and an organic diisocyanate.
Claim 5
Dependent Claim
14 words
A method in accordance with claim 1, where the dipolar aprotic solvent is N-methylpyrrolidone.
Claim 6
Dependent Claim
13 words
A method in accordance with claim 1, where the base is sodium hydroxide.
Claim 7
Dependent Claim
55 words
A method in accordance with claim 1, where the polyimide consists essentially of chemically combined units of the formula, ##STR6## or chemically combined units of the formula, ##STR7## where R and R 1 can be the same or different divalent organic radicals selected from (C 6-20 ) aromatic and (C 1-8 ) aliphatic organic radicals.
Claim 8
Independent Claim
158 words
A method for making an electrocoatable polyamide acid salt mixture having a high water content which comprises 1. heating a solution of a polyimide which is the reaction product of a bis(n-4-carboxyphthalimide) and an organic diisocyanate in N-methylpyrrolidone having at least 15% by weight of such polyimide, to a temperature in the range of between 50° C to 150° C in the presence of sodium hydroxide until the viscosity of the resulting mixture is less than 4,000 centistokes at 25° C, 2. adding sufficient water to the resulting mixture of (1) while its viscosity is less than 4,000 centistokes at 25° C to produce a mixture having from 5-15% by weight solids, 15-40% by weight of N-methylpyrrolidone and 45-80% by weight of water where the sodium hydroxide is used to a concentration which is sufficient to neutralize any carboxy radicals of the polyimide while providing from 0.01 to about 1 meq of sodium hydroxide per gram of polyimide.
Claim 9
Independent Claim
158 words
A method for making an electrocoatable polyamide acid salt mixture having a high water content which comprises 1. heating a solution of a polyimide which is the reaction product of a bis(n-4-carboxyphthalimide) and an organic diisocyanate in N-methylpyrrolidone having at least 15% by weight of such polyimide, to a temperature in the range of between 50° C to 150° C in the presence of sodium hydroxide until the viscosity of the resulting mixture is less than 4,000 centistokes at 25° C, 2. adding sufficient water to the resulting mixture of (1) while its viscosity is less than 4,000 centistokes at 25° C to produce a mixture having from 5-15% by weight solids, 15-40% by weight of N-methylpyrrolidone and 45-80% by weight of water where the sodium hydroxide is used to a concentration which is sufficient to neutralize any carboxy radicals of the polyimide while providing from 0.01 to about 1 meq of sodium hydroxide per gram of polyimide.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-12-26 | 1981-06-27 | 1981-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-12-26 | 1985-06-27 | 1985-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-12-26 | 1989-06-27 | 1989-12-27 | $7700.00 | Window Closed / Lapsed |