Process for the preparation of urea-formaldehyde resins
CA 1290091 C · Owner: Dyno Industrier A.S. · Inventors: Whiteside, Ian R.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Urea-formaldehyde resins which may be cured to give products having a low total extractable formaldehyde content are prepared by the following process:, (i) aqueous 30-50% formaldehyde and urea are mixed in a formaldehyde:urea molar ratio of 2-3:1 at pH 6-11 (ii) this mixture is heated to at least 50°C preferably, to at least 80°C, (iii) a mineral or organic acid is added to bring the mixture to pH 0.5-3.5, (iv) the mixture is heated at a temperature between 80°C and the reflux temperature, preferably for 15 minutes to 1 hour, (v) keeping the temperature at or above 80°C a base is, added to bring the mixture to pH 6.5-9 and (vi) urea is added until the formaldehyde:urea molar ratio is …
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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
- Granted October 1, 1991. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended October 1, 2008.
- 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.