Colour developer composition
CA 2067955 A1 · Owner: The Wiggins Teape Group Limited · Inventors: Taylor, David J.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
31, Abstract, COLOUR DEVELOPER COMPOSITION A colour developing composition for use in pressure-sensitive (carbonless) copying paper sets comprises an inorganic pigment extender (e.g. kaolin, talc or calcined kaolin) and a hydrated silica/hydrated alumina composite. The composition is produced by precipitating the hydrated silica/hydrated alumina composite in the presence of the extender by the following steps:, a) gradually adding a metal silicate solution to a solution of an aluminium salt which is initially at a pH below 4 until the pH of the resulting mixture is approximately 4, thereby to induce some precipitation and to form a sol;, b) gradually adding alkali to said sol to raise the …
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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 May 4, 1992. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended May 4, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by May 4, 2014.
- 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.