Method of de-inking paper and other cellulosic materials

Abstract

A method of de-inking cellulosic fibrous materials comprising: 1) admixing an alkaline reagent with hydrogen peroxide and an aqueous suspension of inked cellulosic fibrous material in amounts whereby the alkaline reagent and hydrogen peroxide react at the ink particle / cellulosic fiber interfaces to dislodge the ink particles from the cellulosic materials; and, 2) removing the dislodged ink particles from the aqueous suspension, wherein the alkaline reagent comprises sodium carbonate or a mixture of sodium carbonate and a) ammonium hydroxide, b) sodium bicarbonate or c) mixtures of sodium carbonate and ammonium hydroxide.

Description

[0001] Research leading to the completion and reduction to practice of the invention was supported in part by Grant No. EEC-9402989 awarded by the National Science Foundation (NSF). The United States Government has certain rights in and to the invention claimed herein.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a process for the treatment of wastepaper. More particularly, the present invention relates to a process for de-inking wastepaper. Most particularly, the present invention relates to a process for enhanced removal of ink particles and non-ink contaminants from wastepaper. Finally, the present invention relates to an improvement over the invention described in U.S. Pat. No. 6,217,706, the entire contents and disclosure of which is incorporated herein by reference. [0004] 2. Description of the Prior Art [0005] In modern times, with the ecological concerns about conservation of raw materials and the rapid decline of availa...

AI Technical Summary

Benefits of technology

[0029] The present invention solves the need for more efficient processes for recycling cellulosic materials by providing an improved and novel method for de-inking such material.

Problems solved by technology

In recent years, however, methods of de-inking which involve cooking and the use of chemicals in aqueous media have become increasingly unsatisfactory for a number of reasons.

Ink formulations have become more and more complex and involve an increasing use of a wide variety of synthetic resins and plasticizers; with each ink having its own special formulation.

Many of the new ink formulations incorporate new pigments, dyes and toners which are difficult to remove by conventional aqueous de-inking chemicals.

The former methods of de-inking and reclaiming wastepaper by chemical and cooking techniques are not adapted for, or adequate for, removing the new types of inks and coating resins.

Due to high contents of thermoplastic resins, the softening action of heat and chemicals alone makes their separation from the fibers very difficult Additionally, the action of heat and chemicals tends to irreversibly set and more firmly bond some of the present day pigments to the fibers and fix dyes and toners to the fibers through staining.

Such material is limited in quantity and is in high demand due to the regulations governing the incorporation of certain percentages of recycled fiber in many paper commodities.

For the above and other reasons, conventional de-inking techniques used in reclaiming processes for wastepaper are no longer efficient or effective for many current needs.

The need for a satisfactory de-inking process has become increasingly important due to greatly expanded utilization of paper and difficulty in disposal of the old papers due to projected lack of landfill sites.

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