WO1997005323A1

WO1997005323A1 - Device to promote reuse of office laser-print paper

Info

Publication number: WO1997005323A1
Application number: PCT/US1995/009747
Authority: WO
Inventors: Richard B. Buie
Original assignee: Buie Richard B
Priority date: 1995-07-31
Filing date: 1995-07-31
Publication date: 1997-02-13
Also published as: AU3208795A

Abstract

A device for removing ink from laser print paper comprising an adhesion roller or belt for heating and applying pressure on the sheet of paper, softening the thermosetting ink film surface, reducing the adhesion of the ink to the sheet of paper, and improving the adhesion of the ink to the adhesion roll. After adhesion of ink to the roll, the paper sheet is peeled away leaving the ink toner fused to the adhesion roll. The roll is then cleaned of fused ink and is ready for the next paper sheet.

Description

Device to Promote Reuse of Office Laser-print Paper

INTRODUCTION:

Two principal uses of office paper in the U.S. are in photocopiers and in printers which use a laser printing technology. Both of these processes use a toner material to create the image. The various types of toners are thermosetting plastic resins with carbon black and other minor constituents to control flow properties, electrical and magnetic properties or other characteristics. This toner is "set" onto the paper by using heat to melt the plastic powder into a solid film adhering to the paper surface. The current invention provides a method of loosening this toner- paper adhesion and lifting the toner back off of the paper so that the paper can be reused.

DESCRIPTION OF THE INVENTION:

Approximately 10 million tons of office paper are used annually in the U.S., and the percentage of this paper used in laser-print (this term includes photocopies papers) can be as high as 70%. In addition, approximately 25,000 tons of toner is used annually in the U.S., with a total world use of 50,000 tons annually. Much of the laser printed paper is used for short term purposes and then discarded, creating a large and rapidly growing stream of office wastepaper. It is estimated that this stream of office waste will reach 12 million tons per year by 1995 in the U.S. Similar trends are occurring in developed countries around the world.

This stream of laser-print wastepaper contains very high quality, bleached cellulose fibers derived from chemically pulping wood chips. To produce such high quality papers it typically requires four tons of green wood to produce one ton of paper. Unfortunately the toner has been found to be very tenacious in its adhesion to the fiber in conventional recycling and deinking processes, and even when detached during conventional recycling the ink particles are large and difficult to separate from the pulp slurry. These deinking processes function in the wet state after the paper has been broken down into individual fibers by mechanical action in large repulper devices. This type of process is only performed at large paper manufacturing sites, and is not suitable for office environments.

The current invention allows reprocessing of quantities of office papers in a dry state, such that offices could reuse the paper and reduce the quantity of paper purchased. This would have several advantages. First, it avoids shipping of quantities of new or recycled paper to the office and of wastepaper or municipal solid waste away from the office. Reuse of one pound of such office paper would eliminate purchase and shipping of one pound of paper to the office and simultaneously eliminate one pound of wastepaper or office waste emanating from the office.

The process uses a softening and lifting off technique which reduces the adhesion of the ink film to the paper sheet. This liftoff process is not sensitive to the ink particle size, and thus the two problems encountered with conventional deinking, namely strong adhesion and large, tough ink particles, are avoided with the dry process proposed here. In addition the process does not require a solvent or solvent recovery process such as other printing removal processes (Mitsubishi Electric Corp., JP04327299). In the current invention the laser-print paper would be collected in a segregated bin or reprocessed immediately in the case of errors or overruns. To process the paper, staples must first be removed and the paper should be jogged to align the edges. This can be done as separate operations or by add-ons of stages of conventional office equipment to the basic configuration.

The first step in the ink removal process is to feed the sheet of paper into the machine and press it into contact with an adhesion roll. Heat and pressure are applied to smooth out creases, flatten the paper, soften the thermosetting ink film, reduce adhesion to the paper, and improve adhesion to the adhesion roll. After adhesion of ink to the roll, the paper sheet is peeled away leaving the toner fused to the adhesion roll. This roll is then cleaned of fused ink and made ready for the next sheet.

After peeling the paper sheet from the adhesion roll, the paper sheet is then reconditioned by rehumidification and calendering to reduce curl and roughness, followed by optical inspection and ejection to an accept or reject output bin. The optical inspection can be performed by photo detectors such that an excessive amount of holes or residual ink will result in rejection of the individual sheet. These reject sheets can be used for lower quality purposes or sent to a conventional paper recycling process.

The success of this process will be somewhat dependent on the toner and type of paper used, and on the final quality demanded by the customer. To achieve best performance it may be necessary to adjust process conditions, such as adhesion roll temperature and pressure, for the particular toner-paper combination used in a given office. In addition to the stripping of the ink with an adhesion roll, if necessary, a "white toner" treatment can be applied to the paper to further improve the paper surface quality using a dry electrostatic coating process and clay-starch- polymer blends.

Claims

CLAIMS:What is claimed is:

1. A device which uses a lift off technique to remove laser-print from a cellulosic paper web and deposit it onto an adhesion roller or belt or suitable surface. Such affinity is caused by the surface compatibility between the plastic ink film surface and the surface of the adhesion roll. Such adhesion is further enhanced and aided by the application of suitable heat and pressure dependent on paper and toner characteristics. Other liquids or gaseous adjuvents may also be used to aid toner removal.

2. A device as specified in claim (1) above in which the sheet is further treated by rehumidification to reduce curl and handling problems.

3. A device as specified in claim (1) above in which the paper is calendered to improve final surface smoothness.

4. A device as specified in claim (1) above in which the paper is then treated with a "white toner" using a dry electrostatic process.

5. A device as specified in claim (1) above in which the paper is optically inspected and sorted into reject and accept bins.

6. A device as specified in claim (1) above in which the paper is treated on both sides in a single pass of the process.