Manufacture of photochromic articles
CA 1339838 C · Owner: Maltman, William Ramsey · Inventors: Ormsby, Mary Elizabeth; Maltman, William Ramsey
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process for producing a polyurethane plastics having photochromic properties, characterised in that the process comprises in a first step incorporating a reversible cleavage photochromic compound into at least one di-isocyanate compound or at least one polyol or a mixture of a di-isocyanate and one or more polyols or into any other component of a mixture which when polymerised, will yield a, polyurethane combining the mixture from the first step with any other necessary components to enable polymerisation to occur; and polymerising the resultant mixture to form a polyurethane incorporating the said photochromic compound. The photochromic polyurethane plastics of the invention are useful …
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
- Granted April 28, 1998. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended April 28, 2015.
- 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.