Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Treatment with particular chemical
Patent
1995-02-08
1997-06-24
Spear, Frank
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Treatment with particular chemical
162 80, D21C 910
Patent
active
056413866
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a process for the bleaching of pulp with hydrogen peroxide in the presence of an aminoalkane diphosphonic acid, as well as the pretreatment of pulp with an aminoalkane diphosphonic acid prior to hydrogen peroxide bleaching thereof. The present invention also relates to the use of an aminoalkane diphosphonic acid in the pretreatment of pulp, in the bleaching of pulp with hydrogen peroxide and in the deinking of pulp.
BACKGROUND OF THE INVENTION
Pulps may vary considerably in their color after pulping, depending on the type of wood, processing method, and other factors. For many types of pulp, bleaching is required to obtain a pulp having the desired level of brightness. Brightness is measured by measuring the reflectance in the blue range (457 nm) using magnesium oxide as a standard (100% brightness).
The most used bleaching agent for pulps is hydrogen peroxide because of its low cost and its effectiveness in bleaching. Many different pulp bleaching processes are known which employ hydrogen peroxide as the bleaching agent. A few examples of such processes can be found in U.S. Pat. No. 4,798,652 and 4,732,650. From these patents it can be seen that the process for bleaching wood pulp often involves a pretreatment step and a bleaching step.
From U.S. Pat. No. 4,798,652 it is known to use diethylene triamine pentaacetic acid (DTPA) in the pretreatment of pulps prior to bleaching them with hydrogen peroxide. The pretreatment is generally carried out at a pulp consistency of less than 5% and the chelating agent is preferably a relatively powerful complexing agent.
From U.S. Pat. No. 4,732,650 it is known to use chelating agents in the pretreatment step prior to bleaching the pulp with hydrogen peroxide. Typical chelating agents used in the pretreatment step include ethylene diamine tetraacetic acid (EDTA), DTPA, triethylene tetramine hexaacetic acid (TTHA) and N-hydroxyethylene diamine triacetic acid (HEDTA).
The article, "Chelating Agents in the Pulp and Paper Industry," Hart, J. Roger, Tappi Journal, Vol. 64, No. 3, pp. 43-44, (March 1981) discusses the role of chelating agents in the bleaching of pulps. This article points out that chelating agents may be used both in the pretreatment of pulp prior to the bleaching step, and as an additive to the bleaching liquor during the bleaching step to stabilize hydrogen peroxide. EDTA and DTPA are mentioned as the preferred chelates.
Another article relating to this subject is, "The Effect of DTPA on Reducing Peroxide Decomposition," Bambrick, D. R., Tappi Journal, Vol. 66, No. 6, pp. 96-100, (June 1985) which gives a detailed discussion on the role of DTPA in hydrogen peroxide bleaching of wood pulp in combination with silicates and magnesium compounds. The article, "Hydrogen Peroxide: Stabilization of Bleaching Liquors," Kutney, G. W., Pulp & Paper Canada, Vol, 86, No. 12, pp. 182-189, (1985) gives a detailed summary of a wide variety of compounds which have been used to stabilize hydrogen peroxide bleaching liquors and thereby obtain a higher pulp brightness. Several different chelates are mentioned including EDTA, DTPA and nitrilotriacetic acid (NTA).
Finally, the article, "Improving Hydrogen Peroxide Bleaching of Mechanical Pulp: The Effect of Silicate Dose and Other Additives," Burton, J. T., et al., Pulp & Paper-Canada, Vol. 86, No. 6, pp. 144-147, (1987) gives some further information on the effects of different additives on the bleaching of pulp with hydrogen peroxide.
Among the chelates employed are DTPA and diethylene triamine pentamethylenephosphonic acid (DTMPA, also referred to as DTPMPA). The ultimate goal of using these additives in the bleach liquor is to replace the silicate additives.
From these last two articles it is apparent that it is desirable to reduce the content of silicates in the present pulp bleaching systems. Further, the chelates used in pulp bleaching suffer from the disadvantage that they are substantially non-biodegradable. One goal of present research in the pulp bleaching f
REFERENCES:
patent: 3899496 (1975-08-01), Schindler et al.
patent: 3979385 (1976-09-01), Wollmann et al.
patent: 4732650 (1988-03-01), Michalowski et al.
patent: 4752354 (1988-06-01), Beurich et al.
patent: 4798652 (1989-01-01), Joyce et al.
patent: 4980171 (1990-12-01), Fels et al.
patent: 5208369 (1993-05-01), Crump et al.
"Hydrogen Peroxide: Stabilization of Bleaching Liquors", Kutney, G.W., Pulp & Paper Canada, vol. 86, No. 12, pp. 182-198, 1985.
"Improving Hydrogen Peroxide Bleaching of Mechanical Pulp: The Effect of Silicate Dose and Other Additives", Burton, J.T., Pulp & Paper Canada, vol. 86, No. 6, pp. 144, 147, 1987.
"Chelant Optimization In De-Inking Formulation", Mathur, I., Pulp & Paper Canada, 94:10, pp. 55-60, 1993.
"Synthesis of 1-Dialkylaminoalkylidenediphosphonic Acids and Their Properties for Complex Formation", Fukuda, et al., Yukagaku, vol. 25, No. 6, pp. 362-364, 1976.
"Acidity and Complex-Formation Properties of Some (Aminomethylene) Bisphosphonic Acids", Gross et al., Zhurnal Obshchei Khimii, vo. 48, No. 9, pp. 1914-1916, 1978.
Kirk-Othmer Encyclopedia of Chemical Technology, vol. 19, p. 413 (Third Edition, 1982).
International Search Report for PCT/EP94/03546 dated Jan. 27, 1995.
"Chelating Agents in the Pulp and Paper Industry", Hart, J., Tappi Journal, vol. 64, No. 3, pp. 43-44, Mar. 1981.
"The Effect of DTPA on Reducing Peroxide Decompsoition", Bambrick, D.R., Tappi Journal, vol. 66, No. 6, pp. 96-100, Jan. 1985.
Boelema Eltjo
Hanter Lambertus Gerhardus Johannus Olde
Navarro Charles Manuel
Van Doorn Marcellinus Alexander
Akzo Nobel nv
Spear Frank
LandOfFree
Aminoalkane diphosphonic acids in pulp bleaching does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Aminoalkane diphosphonic acids in pulp bleaching, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aminoalkane diphosphonic acids in pulp bleaching will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-147135