Canadian Patents Database / Patent 2214957 Summary
Third-party information liability
Some of the information on this Web page has been provided by external sources. The Government of Canada is not responsible for the accuracy, reliability or currency of the information supplied by external sources. Users wishing to rely upon this information should consult directly with the source of the information. Content provided by external sources is not subject to official languages, privacy and accessibility requirements.
Claims and Abstract availability
Any discrepancies in the text and image of the Claims and Abstract are due to differing posting times. Text of the Claims and Abstract are posted:
- At the time the application is open to public inspection;
- At the time of issue of the patent (grant).
|(12) Patent Application:||(11) CA 2214957|
|(54) English Title:||PROCESS TO PRODUCE BRIGHT PULP IN AN ELECTROCHEMICAL REACTOR|
|(54) French Title:||PROCEDE POUR PRODUIRE DE LA PATE BLANCHE DANS UN REACTEUR ELECTROCHIMIQUE|
|(51) International Patent Classification (IPC):||
|(72) Inventors (Country):||
|(73) Owners (Country):||
|(71) Applicants (Country):||
|(22) Filed Date:||1997-11-05|
|(41) Open to Public Inspection:||1999-05-05|
|(30) Availability of licence:||N/A|
|(30) Language of filing:||English|
A process has been developed to bleach pulp in-situ by passing current in an electrolyte
solution capable to generate oxidising bleaching chemicals. Using a rotative stainless steel
cathode and a platinum anode in a carbonate-borate-tetraacetylethylenediamine
electrolyte solution, adding pulp to the said solution and then carrying out electrolysis
between 5 to 80°C with an anode current density between 0.1 to 6 kA/m2, a bleached pulp
with improved brightness was obtained. The rotation of the electrode and recirculation of
pulp slurry in the electrochemical cell were particularly suitable for pulp concentration
above 2 parts of dry pulp per 100 parts of electrolyte solution.
The subject matter which applicants regard as their invention is particularly pointed out
and distinctly claimed as follows:
1. A process for the brightening of delignified Kraft pulp from lignocellulosic material
which comprises treating said lignocelluloic material in an electrolyte solution
containing sodium carbonate, borax, sodium bicarbonate and balance water, said
electrolyte solution having a pH of about 10 and pulp in the said electrolyte solution is
of 0.5 to 6% constancy, by weight of oven dried pulp, wherein the said electrolyte is
undergoing a continuous electrolysis under a current density ranging between about
0.2 to about 6.0 kA/m2 and a temperature of about 6°C. to about 80°C. in the presence
or absence of tetraacetylethylenediamine, compound capable of producing peracetic
acid in-situ in the electrolytic cell, the said electrolysis cell is provided with a rotative
stainless steel cathod to aid mixing of pulp and a pump to circulate the pulp slurry in
the said electrolyte solution.
2. A process as defined in claim 1 wherein the pulp slurry is a homogeneous mixture of
delignified Kraft pulp, electrolytes and chemicals generated in-situ during electrolysis
and balance water to make up the consistency.
3. A process as defined in claim 1 wherein the delignified Kraft pulp is a softwood Kraft
4. A process as defined in claim 1 wherein the stainless steel cathod has sufficient surface
area to mix pulp slurry and provides adequate mixing to prevent deposition of pulp on
cathode and anode surfaces.
5. A process as defined in claim 1 wherein the platinum anode is separated from the
cathode by a specific barrier membrane.
6. A process as defined in claim 1 wherein the tetraacetylethylenediamine compound is
soluble in alkaline solution.
7. A process as defined in claim 6 wherein the said tetraacetylethylenediamine compound
is capable to react with sodium perborate or hydrogen peroxide generated in-situ in the
8. A process as defined in claim 1 wherein the said compound tetraacetylethylenediamine
is consumed by the said in-situ electrochemically generated perborate or peroxide to
produce peracetic acid.
9. A process as defined in claim 1 wherein the said generated peracetic acid has improved
brightening effect on the delignified pulp.
10. A process as defined in claim 1 wherein the electrolysis temperature is between 10°C. to
11. A process as defined in claim 1 wherein the electrolysis time is between 30 min. to 150
12. A process as defined in claim 1 wherein the delignified pulp material is pre-treated
with 0.5% DTPA.
For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee and Payment History should be consulted.
|(41) Open to Public Inspection||1999-05-05|
|Fee Type||Anniversary Year||Due Date||Amount Paid||Paid Date|
|Request for Examination||$200.00||1997-11-05|
|Reinstatement: Failure to Pay Application Maintenance Fees||$200.00||2000-06-12|
|Maintenance Fee - Application - New Act||2||1999-11-05||$50.00||2000-06-12|
|Maintenance Fee - Application - New Act||3||2000-11-06||$50.00||2000-10-10|
|Maintenance Fee - Application - New Act||4||2001-11-05||$50.00||2001-09-10|
|Maintenance Fee - Application - New Act||5||2002-11-05||$75.00||2002-09-11|