Stabilized cd-4 one-part film developer concentrates
CA 2437951 A1 · Owner: Trebla Chemical Company · Inventors: Papai, Laszlo
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Photographic developer replenisher concentrates comprising more reactive developers, like 4(N-ethyl-N-2-hydroxyethyl)-2-methylphenylenediamine (CD-4) undergo rapid oxidation, and consequently have shorten shelf-life , stabilities. Hydroxylamine type derivatives while disclosed as being useful , as a class of antioxidants for stabilizing photographic developer replenishers, most were found to impart either inadequate shelf-life stability for CD-4 developer, or interfered with "satisfactory developer performance." Surprisingly, it was discovered the shelf-life stability of replenisher concentrates comprising CD-4 photographic developer could be extended for periods of 2 years or …
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed February 6, 2002. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended February 6, 2022.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 6, 2024.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.