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Deinking system for carbonate pulping

Inactive Publication Date: 2005-06-23
SOUTHERN IONICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010] The present invention is directed to a process of deinking paper being recycled by a carbonate pulping procedure that is performed in the absence of hydroxides and peroxides. The process entails pulping the paper in the presence of sodium carbonate (generally in combination with a minor amount of sodium silicate) in combination with a non-ionic, alkoxylated alcohol surfactant deinking agent having a cloud point of about 55 to about 85° C., preferably about 60 to about 70° C., and further in combination with two different ink collectors: t

Problems solved by technology

Such systems have been reasonably highly developed for highly alkaline sodium hydroxide / peroxide pulping systems, but little attention has been paid to deinking systems for use in neutral or near-neutral carbonate pulping operations.
The resulting surfactant composition has a cloud point of 45-48° C. With the increasing demands placed upon deinking of recycled paper with the vast increase in recycling of paper products as well as current ink chemistry, i.e. the increasing use of flexographic inks, the Solvay technology even with a surfactant having this low a cloud point this has not worked sufficiently.
However, the mere substitution of those deinking systems into carbonate pulping regimes has not been successful.

Method used

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  • Deinking system for carbonate pulping
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Examples

Experimental program
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Effect test

example 1

[0026] The criticality of surfactant and fatty acids to a successful deinking process for a carbonate pulping operation can be seen in the following comparison of two commercial plant trials, one a success and one a failure because it did not produce any improvement in deinking. The chemical additives used and the deinking results are shown below in Tables 1 and 2.

TABLE 1Successful TrialBase-Inven-Unsuccessful TriallinetionBaselineFailureSodium Hydroxide0.80—0.80-1.05—Sodium Silicate0.600.620.60-0.80   0.25-2.00Sodium Carbonate—0.30—   0.05-1.00Sodium Sulfite—0.10—  0.125-1.95Hydrogen Peroxide0.90—0.90—Chelant0.200.200.20—Fatty acid salts0.040.300.04   0.04-0.053Surfactant,0.16—0.12-0.16   0.05-0.25Cloud point 46-50° C.Cloud point 66-68° C.—0.03——Sodium Hydrosulfite0.150.150.150.15

[0027]

TABLE 2Successful TrialUnsuccessful TrialBaselineInventionBaselineFailureBrightness Gain (ISO)15.015.215.612.8% Efficiency76.880.575.267.3(Ink Removal)Hyper-wash Brightness52.954.252.552.2Hyper-was...

example 2

[0031] Laboratory testing of various systems was performed to compare a number of variables—fatty acids both individual and in combinations at varying levels. The testing was conducted using a Voith, 30 liter lab cell because it had previously been found to have a good correlation to actual mill performance. All mill materials, like furnish, mill water and mill chemicals were used to benchmark the cell against actual plant performance. Further optimization studies were conducted in both the lab and mill environment using this benchmark as a reference point.

[0032] The results of varying the fatty acids are shown in FIGS. 1 and 2. The fatty acid screening runs were conducted at low surfactant doses i.e., <10.00% of the total combined FA / surfactant dose. The surfactant was used essentially as a hydrotrope to generate reliable data (at the same level of rejects) with no rejects / foam surging due to furnish changes. The results show a substantial advantage of hydrogenated / hard fatty acid...

example 3

[0037] Hyper-wash testing was performed at multiple commercial mills to compare the benefits of the present invention (carbonate pulping plus deinking technology) vs. conventional sodium hydroxide technology. The results are shown below in Table 4 in which “Ponderay” is Ponderay Newsprint of Washington, “ARN” is Alabama River Newsprint, of Alabama, and “Augusta” is Augusta Newsprint of Georgia.

TABLE 4PULPER RESPONSEONP / OMGBrightness,ERICMillRatioHydroxideCarbonate% ISOppmPonderay80 / 20yesno51.0270Ponderay80 / 20noyes49.5270ARN95 / 5 yesno52.4260ARN95 / 5 noyes51.0240Augusta80 / 20yesno50.5168Augusta80 / 20noyes53.2178

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Abstract

A process for deinking paper being recycled in a carbonate pulping procedure which is performed in the absence of hydroxides and peroxides is improved by the addition of (a) a non-ionic surfactant deinking agent having a cloud point of about 55 to 85, preferably 60-70, and (b) at least two different fatty acid ink collectors: (i) a C16 to C20 fatty acid and (ii) a C22 to C30 fatty acid, the ink collectors being used in a weight ratio of from about 98:2 to 70:30.

Description

[0001] This application claims the benefit under 35 U.S.C. §119(e) of prior U.S. Provisional Patent Application No. 60 / 526,359 filed Dec. 1, 2003, which is incorporated in its entirety by reference herein.BACKGROUND OF THE INVENTION [0002] Deinking of recycled paper products is becoming more and more important to deal with the substantial increase in paper recycling that is occurring. Such systems have been reasonably highly developed for highly alkaline sodium hydroxide / peroxide pulping systems, but little attention has been paid to deinking systems for use in neutral or near-neutral carbonate pulping operations. [0003] Exclusive of mechanical aspects, conventional highly alkaline peroxide paper pulping processes which incorporate flotation deinking procedures can be divided into three distinct chemical regimes: pulper, floatation, and bleaching. A typical sodium hydroxide / hydrogen peroxide pulping regime operates at high pulper pH, e.g. about 8.5-11.0, and requires two separate bl...

Claims

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Application Information

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IPC IPC(8): D21C5/02
CPCD21C5/027Y02W30/64
Inventor ROBINSON, PETER M.PRESLEY, JOHN RICHARD
Owner SOUTHERN IONICS