Aqueous electrically insulating varnish and a process for its production

• US 4,169,085 A
• Filed: 01/18/1978
• Issued: 09/25/1979
• Est. Priority Date: 01/20/1977
• Status: Expired due to Term

• Current Assignee: Dr BECK & Company AG
• Original Assignee: Dr BECK & Company AG
• Inventors: Janssen, Harald, Hansch, Ferdinand, VON Loh, Knut
• Primary Examiner(s): Morris, Theodore
• Application Number:
  US05/870,491
• Time in Patent Office: 615 Days
• Field of Search: 260/29.2 N
• US Class Current: 524/879
• CPC Class Codes: C08G 73/10 Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
• CPC Class Codes: H01B 3/306 Polyimides or polyesterimides

Abstract

An aqueous electrically insulating varnish is provided along with a process for producing the varnish; the process comprises the steps of reacting cyclopentane tetracarboxylic acid with dicyclic, diprimary aromatic diamine in the presence of water and neutralizing the condensation product to form a varnish.

Claims

1. An aqueous electrically insulating varnish produced by a process comprising the steps of reacting cyclopentane tetracarboxylic acid with a dicyclic, diprimary aromatic diamine in the presence of water, and neutralizing the condensation product with a volatile base so as to form a varnish.

2. The varnish of claim 1, said step of reacting comprising mixing said cyclopentane tetracarboxylic acid and said diamine in amounts corresponding to a molecular ratio of said acid to said diamine of 0.9-1.1:

1.1-0.9 respectively in water, adding a water-miscible solvent having a boiling point of about 200°

-300°

C. in an amount up to 20% by weight of both said acid and said diamine, heating the thus-formed mixture to boiling and distilling off water until a predetermined acid number of 100-150 is attained, and adding a base which is a member selected from the group consisting of ammonia and amines to thereby neutralize the acidic mixture.

3. The varnish of claim 1, said step of reacting including adding a water-miscible organic solvent.

4. The varnish of claim 1, said cyclopentane tetracarboxylic acid being in a dianhydride form.

5. A process for producing an aqueous electrically insulating varnish, comprising the steps of reacting cyclopentane tetracarboxylic acid with a dicyclic, diprimary aromatic diamine in the presence of water and neutralizing the condensation product with a volatile base, so as to form a varnish.

6. The process of claim 5, said step of reacting comprising mixing said cyclopentane tetracarboxylic acid and said diamine in amounts corresponding to a molecular ratio of said acid to said diamine of 0.9-1.1:

1.1-0.9 respectively in water, adding a water-miscible solvent having a boiling point of about 200°

-300°

C. in an amount up to 20% by weight of both said acid and said diamine, heating the thus-formed mixture to boiling and distilling off water until a predetermined acid number of 100-150 is attained, and adding a base which is a member selected from the group consisting of ammonia and the amines to thereby neutralize the acidic mixture.

7. The process of claim 5, said step of reacting including adding a water-miscible organic solvent.

8. The process of claim 5, said cyclopentane tetracarboxylic acid being in a dianhydride form.

9. The process of claim 6, said base being a member selected from the group consisting of amines having a boiling point not greater than 200°

C.