METHOD AND APPARATUS FOR DEINKING PAPER

Abstract: Deinking a sheet of paper by removing toner thereon including wetting the sheet of paper with a non-toxic, water soluble deinking solution which comprises water, for wetting the sheet of paper to swell the fibers of the sheet, a water soluble surfactant for lowering the surface tension of the water to enhance wetting of the sheet with the water, and no more than two water soluble solvents for softening the toner, without dissolving the toner, and for breaking the bond between the toner and the sheet; removing the softened toner from the sheet, creating toner particles; heating the sheet to vaporize the deinking solution, removing the solution from the sheet; and calendering the sheet of paper to return the sheet to the predetermined dimensions for immediate reuse.

Description: METHOD AND APPARATUS FOR DEINKING PAPER Related Inventions This application is a continuation-in-part application of U.S. Serial No. 08/652,146 entitled "Method and Apparatus for Deinking Paper" filed May 13, 1996. Field of Invention This invention relates to a method and apparatus for deinking paper, and more particularly, deinking paper which contains non-impact ink using a water soluble, non-toxic, non-hazardous deinking solution. Background of Invention Paperwaste constitutes 31% of all residential and commercial waste by weight and well over half by volume in the United States. Office wastepaper from laser printers, photocopiers and facsimile machines comprise a significant portion of the total amount of wastepaper in the United States. Laser ink wastepaper makes up 24% by weight and about 40% by volume of all domestic and industrial waste in the United States. Printing on paper is accomplished using one of two types of inks, namely, impact and nonimpact inks. Impact inks are those used in, for example, letter-press and lithography techniques. Impact inks are composed of carbon black or a dye and are typically water soluble. Non-impact inks, or "laser" inks, are those used, for example, in laser printing, photocopying and facsimile machines. Impact printing does not fuse the ink into the paper and is, therefore, easy to remove from the paper. Paper printed on by impact methods has been successfully deinked for years. However, non-impact ink, i.e. toner, is difficult to remove because the ink particles fuse into the paper and to one another. Presently, paper printed on with non-impact ink is recycled in large quantities in paper mill environments using toxic chemicals which pose a threat to the environment as well as humans working with or near the chemicals. Non-impact inks are composed of carbon black, pigments, resins and iron oxide. Typically, the paper is submitted in large quantities to a chemical tank to soften the toner. The paper is then repulped to remove the toner. Printing with such inks occurs between 160°C and 204 °C. Similarly, removing these inks typically requires comparable temperature ranges. This process is expensive and does not produce high quality recycled paper. Moreover, there is a significant cost to individuals who recycle for hauling the paper to the remote recycling locations. Most research aimed at recycling this paper is focused on developing new and better chemical formulations on the one hand, while designing new and better repulping plants on the other. Combined mechanical/chemical processors are currently being developed and tested. There still exists, however, problems with separating the toner particles from the paper sludge. As a result, numerous toxic and caustic chemicals are being used in large quantities while fiber yield is only approximately 70%. Such chemicals include sodium hydroxide for fiber swelling, toner break-up and dispersion; sodium silicate for peptization, alkalinity and peroxide stabilization; sodium carbonate for alkalinity, buffering and water softening; sodium phosphates for alkalinity, peptization, toner dispersion and metal ion sequestration; solvents for solvation and softening; surfactants for flocculation, dispersion, wetting, emulsification, solubilization and peptization; polymeric dispersants for dispersion, anti-redeposition and sequestration; hydrogen peroxide, sodium hydrosulfate and chlorine for bleaching and color stripping. This is only a partial list of the chemicals typically used; these chemicals are used in various combinations at various stages of recycling and deinking. As discussed above, most of these chemicals are hazardous, toxic and caustic and pose a serious health threat to those who come into contact with them or their vapors. Small scale, individual recycling units which remove toner and are capable of recycling paper printed on with non-impact inks have been developed. One such device is disclosed in United States Patent No. 5,463,447 issued to Kurotori, et al. which discloses removal of toner from sheets of paper which was printed on by a photocopier. However, that device requires that the developer used in the photocopier be improved such that the adhering force of the toner is weak enough to allow the toner to be subsequently removed from the paper on which the toner image is formed. Thus, the device of that patent does not properly deink paper unless it was first printed on with a specific toner having a sufficiently weak adhering force. United States patent 5,528,788, issued to Yamamoto et al. discloses a deinking machine which uses a deinking fluid containing a laundry list of chemicals. While the exact chemical composition is not specified, it discloses a fluid which consists of at least eight components and as many as twenty four. Moreover, even though the exact formulation is not disclosed, it is clear that what is disclosed is not water soluble because of the solvents used. Additionally, the list of chemicals provided by Yamamoto will not produce a deinking fluid with a pH of 6.5-7.5. Finally, Yamamoto teaches that a surfactant is not necessary. Accordingly, Yamamoto does not take into consideration the HBL of the surfactant which is critical to the wetting properties of the deinking fluid. Another device disclosed in United States Patent No. 5,353,108 issued to Tsukamoto is used for cleaning printed paper. However, the paper to be cleaned must be erasable paper comprised of a substrate and a releasing agent. The paper is fed between an adhesion roller and a platen. There is a heat soluble resin in a molten state on the surface of the adhesion roller and heat applied to the heat soluble resin by means of a heat source causes the heat soluble ink on the erasable paper to be enveloped therein and pealed from the surface of the paper. These devices have limited applications and may not be used generally with just any piece of paper containing non-impact ink. That is, they are only useful with specific types of paper, e.g. erasable, or with used paper that contains a specific toner with weak adhering forces. Apart from the need for and benefits of recycling paper, there is also a need for maintaining privacy and security of information which is not intended for disclosure and dissemination beyond a business or agency, or even beyond a select few within such organizations. Business methods and practices are often trade secrets and are not intended to be viewed by persons other than those employed by the company and even then often by only a select few. The same is true with government agencies, professional entities, and the like which have a duty of confidentiality and secrecy to protect clients and national security. Such requirements severely limit what may be done with documents containing sensitive, private or secret information. Obviously, such documents may not be sent out to be recycled. Moreover, shredding of such documents can often be thwarted by re-piecing the shreds. Accordingly, there is a need for a method and apparatus for deinking paper which allows such documents to be recycled without compromising the security of the information contained in those documents. Typical costs incurred for shredding and recycling can be as much as two cents per sheet, the recycling yield of which is very low. Similarly, conventional recycling may cost one cent per sheet with a yield of 70%. This does not even consider the cost to transport the paper to be recycled. Summary of Invention It is therefore an object of this invention to provide a method and apparatus for deinking paper containing ink printed thereon by non-impact printing methods and printed on any type of paper. It is a further object of this invention to provide such a method and apparatus for deinking paper which is accomplished by a small, self-contained, sealed unit. It is a further object of this invention to provide such a method and apparatus for deinking paper which is non-toxic and non-hazardous to users and the environment and which may be utilized in an office environment. It is a further object of this invention to provide such a method and apparatus for deinking paper which improves the quality of the paper recycled and further allows immediate reuse of the recycled paper. It is a further object of this invention to provide such a method and apparatus for deinking paper which is less expensive than prior methods. It is a further object of this invention to provide such a method and apparatus for deinking paper regardless of the age of the paper. It is a further object of this invention to provide such a method and apparatus for deinking paper which is extremely cost effective in comparison to purchasing new paper. It is a further object of this invention to provide such a method and apparatus for deinking paper which does not need to dissolve the toner to be removed. It is a further object of this invention to provide such a method and apparatus for deinking paper which collects the removed toner for recycling. It is a further object of this invention to provide such a method which collects the vaporized deinking solution for condensing and recycling. It is a further object of this invention to provide such a method and apparatus for deinking paper which improves security by preventing detection of the information previously printed on the recycled paper. The invention results from the realization that a truly effective, safe and cost efficient system for deinking paper can be achieved by using a non-toxic, water soluble deinking solution comprising water, a water soluble surfactant and no more than two water soluble solvents to wet the paper, thereby thoroughly swelling the paper fibers, softening the toner thereon, and breaking the bond between the toner and the paper without dissolving the toner, allowing easy removal, collection and recycling of the toner as well as collection, condensation, and recycling of the deinking solution without exposing the user to toxic chemicals and fumes to produce improved quality paper for immediate reuse and prevent detection of information previously printed thereon. This invention features a method of deinking a sheet of paper by removing toner thereon by wetting the sheet of paper with a non-toxic, water soluble deinking solution comprising water, for wetting the sheet of paper to swell the fibers of the sheet, a water soluble surfactant for lowering the surface tension of the water to enhance wetting of the sheet with water, and no more than two water soluble solvents for softening the toner, without dissolving the toner, and for breaking the bond between the toner and the sheet. The softened toner is removed from the sheet, creating toner particles, the sheet is heated to vaporize the deinking solution, the deinking solution is removed from the sheet, and the sheet of paper is calendared for immediate reuse. In a preferred embodiment the water and the surfactant may be in a 10:1 ratio in the deinking solution. The surfactant may be selected from the group consisting of Triton X-155, Triton X-305, Triton X-405 and BRD 2311. The deinking solution may include a solvent in a ratio of 3:10 to the water and surfactant. The solvent may be a C12-C14 aliphatic saturated hydrocarbon. The solvent may be an ether. The solvent may be Diethylene Glycol n-Butyl Ether. The toner particles may be collected and recycled. The vapors produced by the heating may be collected. The collecting of the vapors may include condensing the collected vapors back to liquid deinking solution and recycling the condensed deinking solution. Removing may include wiping the sheet to remove the toner particles. Wiping may include a rotating coiled brush to remove the toner particles from the sheet. Wiping may include collecting the toner particles from the coiled brush. Collecting may include combing the coiled brush to remove the toner particles from the brush. Combing may include depositing the toner particles in a recovery compartment. Heating may include blowing hot air on the sheet to dry the sheet. The hot air may have a temperature in the range of 60°C to 70°C. Calendering may include feeding the sheet between heated rollers. The rollers may have a temperature in the range of 20 °C to 60 °C. The water may comprise 75% to 87%> of the deinking solution. The surfactant may comprise l%-3% of the deinking solution. The solvent may comprise 15%-20% of the deinking solution. The deinking solution may have a pH of 6.5-7.5. The solvent may comprise a glycol ether and an aromatic hydrocarbon. The glycol ether may be selected from the group ethylene glycol n-Butyl ether, diethylene glycol n-Butyl ether, ethylene glycol n-Butyl acetate and diethylene glycol n-Butyl acetate. The aromatic hydrocarbon may be selected from the group ethyl 4-methoxybenzoate, ethyl 3-methoxybenzoate and 2-methoxybenzoic acid ethyl ether. The invention also features a system for deinking a sheet of paper by removing toner thereon including means for wetting the sheet of paper with a non-toxic, water soluble deinking solution comprising water, for wetting the sheet of paper to swell the fibers of the sheet, a water soluble surfactant for lowering the surface tension of the water to enhance wetting of the sheet with water, and no more than two water soluble solvents for softening the toner, without dissolving the toner, and for breaking the bond between the toner and the sheet. There are means for removing the softened toner from the sheet, creating toner particles, means for heating the sheet to vaporize the deinking solution, means for removing the solution from the sheet, and means for calendering the sheet of paper for immediate reuse. In a preferred embodiment the water and the surfactant may be in a 10: 1 ratio in the deinking solution. The surfactant may be selected from the group consisting of Triton X-155, Triton X-305, Triton X-405 and BRD 2311. The deinking solution may include a solvent in a ratio of 3:10 to the water and surfactant. The solvent may be a C12-C14 aliphatic saturated hydrocarbon. The solvent may be an ether. The solvent may be Diethylene Glycol n-Butyl Ether. There may be means for collecting the toner particles. There may be means for recycling the toner particles. There may be means for collecting the vapors produced by the heating. The means for collecting the vapors may include means for condensing the collected vapors back to liquid deinking solution and means for recycling the condensed deinking solution. The means for removing may include means for wiping the sheet to remove the toner particles. The means for wiping may include a rotating coiled brush to remove the toner particles from the sheet. The means for wiping may include means for collecting the toner particles from the coiled brush. The means for collecting the toner particles may include means for combing the coiled brush to remove the toner particles from the brush. The means for combing may include depositing the toner particles in a recovery compartment. The means for heating may include means for blowing heated air on the sheet to dry the sheet. The heated air may have a temperature in the range of 60°C to 70°C. The means for calendering may include heated rollers. The rollers may have a temperature in the range of 20°C to 60°C. The water may comprise 75% to 87% of the deinking solution. The surfactant may comprise l%-3% of the deinking solution. The solvent may comprise 15%-20% of the deinking solution. The deinking solution may have a pH of 6.5-7.5. The solvent may comprise a glycol ether and an aromatic hydrocarbon. The glycol ether may be selected from the group ethylene glycol n-Butyl ether, diethylene glycol n-Butyl ether, ethylene glycol n-Butyl acetate and diethylene glycol n-Butyl acetate. The aromatic hydrocarbon may be selected from the group ethyl 4-methoxybenzoate, ethyl 3-methoxybenzoate and 2-methoxybenzoic acid ethyl ether. Disclosure of Preferred Embodiment Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which: Brief Description of the Drawings Fig. 1 is a perspective view of a paper recycling system for deinking paper according to this invention; Fig. 2 is a schematic cross-sectional view of the system of Fig. 1; Fig. 3 is a top plan view of Fig. 2; and Fig. 4 is a flow chart depicting the deinking method of this invention. Detailed Description of the Preferred Embodiment There is shown in Fig. 1 paper recycling system 10 for deinking paper. While this system is directed primarily to deinking paper containing non-impact ink, it is just as well suited for deinking paper containing impact ink. Non-impact ink is toner which is applied to paper by laser printers, photocopiers and facsimile machines, for example. System 10 is a compact, self- contained, sealed unit having typical dimensions of 38 inches in length, 23.5 inches in width and 38 inches in height, requires no external connections other than the power cord and is very much suited and safe for office environments. System 10 includes used paper tray 12, cleaned paper tray 14 and rejected paper tray 16 for receiving rejected paper not capable of being recycled by system 10. An electronic sensor, not shown, scans each sheet in order to detect whether any toner still resides on the paper. If so, the paper is sent to rejected paper tray 16. System 10 operates under the control of control unit 18 which may include control panel 19 having typical indicator lights such as power on, ready, check paper, add deinking fluid, clean roller and switches for turning the power on and off, starting and stopping the cleaning process and a sensitivity slide used to indicate that a sheet has been completely cleaned or decopied or that it should be passed through system 10 for further cleaning. The wetting, wiping and drying stations which accomplish the deinking according to this invention and which are depicted in Fig. 2 are contained within compartment 20. Supply compartment 22, which has doors 23 and 24, may be used for chemical storage. System 10 may RECTIFIED SHEET (RULE 91) ISA/EP be mounted on wheels 25, only two of which are shown in this view. Compartment 20, shown in detail in Fig. 2, receives paper at input 30 from used paper tray 12 (not shown). Heat plate 29 heats the paper somewhere between 25 °C and 60 °C in order to soften the toner prior to introduction into compartment 20. The paper is fed into compartment 20 by nip rollers 31 and 32 which provide individual sheets of used paper, e.g. sheet 33, to deinking solution applicator station 34 under the control of the control unit 19, Fig. 1. Proximate deinking solution applicator station 34, sheet 33 encounters driven carrier belt 36 which transports the sheets of used paper through compartment 20 until they are deposited within cleaned paper tray 14. Driven carrier belt 36 is propelled by main roller drive 38 which includes motor 40 that drives main roller 42 in a clockwise direction. Belt 36 is guided by idler rollers 44-50 and is driven in a counter-clockwise direction by main roller 42. Idler rollers 46-50 include spring tension adjustments 46a-50a which adjust the tension of driven carrier belt 36. Station 34 includes primary roller 52 which is also driven by main roller drive 38 to rotate in the clockwise direction. Roller 52 in conjunction with intermediate roller 54 rotate deinking solution roller 56. Roller 56 is disposed in trough 58 which holds an amount of deinking solution supplied from reservoir 60. Reservoir 60 is preferably a removable cartridge much like a toner cartridge in, for example, a photocopier and it slowly dispenses the deinking solution into trough 58. As roller 56 rotates it transports deinking solution from trough 58 to intermediate roller 54, which in turn transfers the solution to primary roller 52. As sheets of paper are moved along on driven carrier belt 36, the solution from primary roller 52 is applied to each sheet. Alternatively, deinking solution may be sprayed onto sheet 33 by spray nozzle 57. Spray nozzle 57 sprays the deinking solution evenly in an amount to sufficiently soak sheet 33. It has been found that at 60 °C, toner may easily be removed after 3-4 seconds. This time necessarily increases with a decrease in temperature. The deinking fluid is composed of water and two water-soluble solvents. A surfactant may be included to enhance performance. The pH of the deinking fluid is known to be in the range of 6.5 to 7.5, typically 6.8, and its density and boiling point approximately 1.0 and 100°C respectively, similar to water. Thus, it is non-hazardous to the user and the environment. Moreover, the components evaporate with the water, eliminating the requirement of rinsing. The amount of water in the total fluid should be between 75% and 87% by volume. When a liquid comes into contact with a solid, the molecules at the interface get attracted to the solid. The molecules spread over the solid and the surface area of the liquid increases. This phenomenon is called wetting. Good wetting facilitates rapid penetration of chemicals into the fiber network of the paper and into the fiber-toner contact area. This helps to break up and separate toner from fiber. If the percentage of water in the total fluid appreciably exceeds 87%, the fluid becomes too aqueous. This causes the paper to become too soft to the extent that it may disintegrate under even minimal mechanical pressure, such as pressure from a coiled brush. If the percentage of water is appreciably below 75%, the paper fibers may harden because of physical bond formation. Hydrocarbon solvents are known to form strong physical bonds with certain cellulosic materials, thereby strengthening them. However, the paper will not thoroughly wet, thus the toner will not become thoroughly softened. In this situation toner peel-off with the aid of a brush is more difficult. The volume of the two solvents is usually no greater than 20%> and not below 10%. Solvents that can dissolve most printing inks are available. They are, however, expensive and cannot be used cost effectively for recycling. Another drawback is miscibility in water. In order to be effective, a solvent is supposed to be immiscible in water at low concentrations (<1000 ppm). Unfortunately, most of these solvents are miscible in water. EPA regulations further exclude the use of some good solvents for environmental concerns, especially halogenated hydrocarbons. Consequently, the most commonly used solvents are aliphatic hydrocarbons. It has been found surprisingly, that a formulation composed of water and two water miscible solvents can soften and even dissolve toner, depending on their percentages and temperature. However, in a preferred embodiment, the toner is only softened, not dissolved. This prevents discoloration of the decopied paper and recycling of the solution. The two solvents may be a glycol ether or a glycol ester and an aromatic hydrocarbon. Examples of glycol ethers and glycol esters include Ethylene Glycol n-Butyl Ether, Diethylene Glycol n-Butyl Ether, Ethylene Glycol n-Butyl Acetate, and Diethylene Glycol n-Butyl Acetate. The aromatic solvent may be selected from among aromatic esters and alkyl phenols such as Ethyl 4-Methoxybenzoate, Ethyl 3-Methoxybenzoate, and 2-Methoxybenzoic Acid Ethyl Ether. In addition to the solvents discussed above, the solvent may also be a C12-C14 aliphatic saturated hydrocarbon or an ether. It is preferred that the solvent be a solvent 900, specifically Diethylene Glycol n-Butly Ether. In another formulation that same solvent may be mixed in a 3 : 10 ratio to the water and surfactant mix. The ratio of the aliphatic solvent to that of the aromatic solvent may typically vary between 4: 1 and 5:1 depending on whether a surfactant is included. The hydrophilic-lipophilic balance (HLB) of a given surfactant can be altered by varying the temperature of formulation, or by addition of solvents, or both. The type(s) and or amount(s) of solvent(s) used are critical in obtaining or maintaining a desired HLB. In the present invention, these solvent ratios are critical to maintaining and or obtaining an HLB of 7-9. If the combined percentage of the two solvents appreciably exceeds 20%, there is tendency towards fusion and toner peel-off with the aid of a brush is more difficult. Thus, too much solvent permits the toner to stick and smear on the sheet while too little does not allow breaking of the toner-paper bond. In a preferred embodiment, the total amount of surfactant in the deinking solution may not exceed 5% and is preferably in the ranges of 1-3%. Since a surfactant in the present circumstances mainly improves wetting by lowering the surface tension of water, it typically need not exceed 5%. If there is too little surfactant there is insufficient wetting of the paper and too much will cause smearing of the toner. Surfactants are surface active materials. Surfactants function in deinking by lowering the surface tension of water, thereby rendering wetting more effective. Since the water also carries the solvent, the solvent becomes more effective. Thus, they adsorb onto surfaces to aid in ink removal, solubilization, dispersion, and emulsification. Surfactants therefore principally increase the speed of deinking. Surfactants are most useful when carefully selected and balanced in any deinking formulation. A surfactant contains an organic portion which has affinity for oils (hydrophobe), and another portion which has affinity for water (hydrophile). There are two types of surfactant, nonionic and ionic. In a nonionic surfactant, the hydrophilic portion is usually a highly polar group, while in an ionic surfactant, it is an ionic group. In both types, the hydrophobic portion is a long chain hydrocarbon residue. Surfactant chemistry is complicated and still little understood. Whereas one surfactant may work for a particular toner and grade of paper, it may not do so well for others. The type of solvent used along with a surfactant may modify the HLB of the surfactant, thereby affecting its ability to lower the surface tension of water. With an HLB of 4-6, the surfactant acts as a water-in-oil emulsifier. Similarly, with an HLB of 8-13 the surfactant acts as an oil-in- water emulsifier. At 13-15 the surfactant acts as a detergent and at 15-18 it acts as a solubilizing agent. Thus, the HLB of the deinking solution according to the present invention is 7-9 so that the surfactant will act as a wetting agent. Commonly used surfactants are ethoxylated alkyl phenols, ethoxylated linear alcohols, and fatty acid soaps. Because of their low percentage, however, no rinsing is required as most of the surfactant is removed with the toner. The surfactant may be for example Triton X-155, Triton X-305, Triton X-405; however, the preferred surfactant is BRD-2311. The chemical composition of these surfactants are as follows: Triton X-155 Chemical Components: MethyleneBisdiamyl-Phenoxypolyethoxyethanol/67906-06-3 ; Isopropano 1/67-63; water/7732-18-5; Polyethylene Glycol/25322-68-3. Manufacturer: Union Carbide Triton X-305 Chemical Components : Poly(Oxy- 1 , 1 ,3 ,3-Tetramethylbutyl)Penyl-W-Hydroxy-/9036- 19-5;Poly(oxy-l,2-Ethanediyl_,A-Hydro-W-Hydroxy-/25322- 68-3 ;water/7732- 18-5 Manufacturer: Union Carbide Triton X-405 Chemical Components: Octoxyphenoxypolyethoxyethanol/9036-19-5;water/7732-18- 5;PolyethyleneGlycol/25322-68-3 Manufacturer: Union Carbide BRD-2311 Chemical Components: This surfactant is a trade secret; however, it is believed to be either an ethoxylated linear Alcohol or an ethoxylated Alkyl Phenol or both and it contains some Na+. Manufacturer: Buckman Laboratories An additional formulation which may be used includes adding an enzyme in a ratio in 1 :33 to the basic formulation containing the water and surfactant in a 10:1 ratio. The enzyme is preferably BUZYME 2522. This enzyme is manufactured by Buckman Laboratories and is also a trade secret. This formulation works best when the surfactant used is BRD-2311. After each sheet of paper leaves station 34, it continues uninterrupted to wiping station 64. Alternatively, each sheet may be transported to station 62 where the movement of the driven carrier belt 36 is stopped for approximately 10-15 seconds in order to allow the non- impact ink (toner) to be softened by the deinking solution, depending on the temperature of the system. Additional heat may be applied by heater 63 to facilitate softening of the toner forgoing the need to stop the drive belt. After the non-impact ink has been softened, the paper is moved to wiping station 64 which includes primary roller 66 also driven by main roller drive 38. Primary roller 66 includes a coiled brush which contains bristles 67 on its surface which gently wipe the surface of the paper as it passes through wiping station 64 removing the toner particles. The bristles are typically formed of a low density polypropylene material. Comb roller 68 may be used to continuously remove the toner ink particles from the bristles of roller 66. Wiping station 64 includes recovery station 65. The removed particles are collected by recovery station 65 which includes recovery compartment 69 which may be a removable cartridge similar to a standard photo copier toner cartridge. The gentle wiping removes most of the toner without disturbing the fibers of the paper. Although roller 66 is configured to rotate in the direction of the movement of the sheets of paper through system 10, roller 66 could be rotated in the opposite direction. Also, roller 66 may be oriented at an angle to sheet 33a as shown in Fig. 3 in order to direct toner particles to recovery compartment 69a, given the coiled nature of roller 66. Scraper 70, Fig. 2, removes the toner from the surface of primary roller 66. There may be a second wiping station 72 configured in the same manner as is wiping station 64, in that it includes a primary roller 74, bristles 75, comb roller 76, scraper 78 and recovery compartment 79. This station operates to provide additional wiping action to remove any remaining traces of toner. Dryer station 92 includes a blower unit 94 and duct 96 which directs a heated air flow generated by blower 94 towards the surface of the paper sheets as they pass through dryer station 92 to dry the sheets. The air which impinges upon the sheets is typically heated at a temperature in the range of between 60° and 70 °C. Because the deinking solution is water soluble having a pH of 6.5-7.5, typically 6.8, and boiling point of 100°C the solution components evaporate without leaving any residue, thus rinsing of the sheet is not necessary. Fluid recovery station 88 includes a fan 80 which draws the evaporated deinking solution through duct 82. Condensing means 84 comprises a condensing coil which condenses the vapors back into a liquid; the liquid is collected in liquid recovery compartment 86. Liquid recovery compartment 86 includes a replaceable cartridge which may be removed when full and replaced with an empty recovery compartment. This allows not only recycling of the deinking solution, but also prevents the vapors from the fluid, although non-toxic to the user, from escaping into the atmosphere which may cause an unpleasant odor. Once recovery compartment 86 is full, it may be removed and returned either to wetting station 34, replacing reservoir 60, or it may be disposed of after a predetermined number of uses for disposal, or other use. Alternatively, the condensed fluid may be fed back directly to reservoir 60. Because the deinking solution of the present invention does not dissolve the toner, the condensed deinking solution is not contaminated and is thus reusable thereby saving on the cost of operating the decopier. Thus, condensing coil 84a located within recovery duct 86a allows immediate reuse of recycled fluid. Accordingly, the deinking system of the present invention not only provides a deinking solution which is non-toxic and non-caustic, but further, is friendly to the environment because the solution as well as the toner particles are recycled and not merely disposed of. After sheet 33 exits dryer station 92 it is provided to compression roller 98, driven by main roller drive 38, which may be heated to a temperature in the range of 90-100°C. This further dries the sheet, removing from the paper any wrinkles that may be present, and returning the sheet to its original size before it is deposited within cleaned paper tray 14. The sheets are then ready for immediate reuse. Moreover, the quality of the sheets is in fact improved as a result of the deinking solution. The solvent strengthens the paper fibers, improving the quality of the sheet due to the strong physical bonds formed by the hydrocarbons with the cellulose of the paper. This further extends the life of the paper, allowing decopying up to five times per sheet. Security measures require that the information previously contained on the sheet cannot be detected. Infrared tests conducted on sheets decopied according to the present invention by the U.S. Army Criminal Investigation Laboratory at Forest Park, GA. have demonstrated that no toner is left on the sheets. The tests included exposing the decopied sheets to IR (infrared); ultraviolet (UV) - short and long wave; polilight and Argon laser light. Flow chart 100, Fig. 4, illustrates the method of deinking according to this invention. In step 102 the deinking solution which is formulated as described above, is applied to the used paper which is to be deinked. The paper is then gently wiped at step 104 to remove the softened toner from the paper without disturbing the fibers of the paper. The toner particles are removed from the brush and collected for recycling. At step 106 the deinking solution is removed by heating the paper at temperatures between 60° and 70°C. The deinked paper is dried, step 108, and the evaporated deinking solution is collected and condensed for recycling. The dried paper is compressed, step 110, to further dry the paper and to remove from the paper any wrinkles that may be present in preparation for immediate reuse, step 112. The system and method of this invention produces improved quality, recycled paper cost effectively on a relatively small scale from any type of paper of any age containing non-impact ink printed thereon by any non-impact ink printed method. Moreover, the deinked sheets retain no trace of the information previously printed thereon and is safe to both the user and the environment. The invention yields 100% of the recycled material at a cost of .3 cents per sheet. Although specific features of this invention are shown in some drawings and not others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. Other embodiments will occur to those skilled in the art and are within the following claims:

Claims: CLAIMS I. A method of deinking a sheet of paper by removing toner thereon comprising: wetting the sheet of paper with a non-toxic, water soluble deinking solution including; water, for wetting the sheet of paper to swell the fibers of said sheet, a water soluble surfactant for lowering the surface tension of said water to enhance wetting of the sheet with said water, and no more than two water soluble solvents for softening the toner, without dissolving the toner, and for breaking the bond between the toner and the sheet; removing the softened toner from the sheet, creating toner particles; heating the sheet to vaporize the deinking solution, removing the solution from the sheet; and calendering the sheet of paper to return the sheet to its original size for immediate reuse. 2. The method of deinking paper of claim 1 in which said water and said surfactant are in a 10:1 ratio in said deinking solution. 3. The method of deinking paper of claim 2 in which said deinking solution further includes a solvent in a ratio of 3:10 to said water and surfactant. 4. The method of deinking paper of claim 3 in which said solvent is a C12-C14 aliphatic saturated hydrocarbon. 5. The method of deinking paper of claim 3 in which said solvent is an ether. 6. The method of deinking paper of claim 3 in which said solvent is Diethylene Glycol n-Butyl Ether. 7. The method of deinking paper of claim 1 further comprising collecting the toner particles. 8. The method of deinking paper of claim 7 further comprising recycling the toner particles. 9. The method of deinking paper of claim 1 further comprising collecting the vapors produced by said heating. 10. The method of deinking paper of claim 9 in which collecting the vapors includes condensing the collected vapors back to liquid deinking solution and recycling the condensed deinking solution. 11. The method of deinking paper of claim 1 in which removing includes wiping the sheet to remove the toner particles. 12. The method of deinking paper of claim 11 in which wiping includes rotating a coiled brush to remove the toner particles from the sheet. 13. The method of deinking paper of claim 12 in which wiping further includes collecting the toner particles from said coiled brush. 14. The method of deinking paper of claim 13 in which collecting includes combing the coil brush to remove the toner particles from the brush. 15. The method of deinking paper of claim 14 in which combing includes depositing the toner particles in a recovery compartment. 16. A method of deinking paper of claim 1 in which heating includes blowing hot air on the sheet to dry the sheet. 17. The method of deinking paper of claim 16 in which the hot air has a temperature in the range of 60 °C to 70 °C. 18. The method of deinking paper of claim 1 in which calendering includes feeding the sheet between heated rollers. 19. The method of deinking paper of claim 18 in which the rollers have a temperature in the range of 20 °C to 60 °C. 20. The method of deinking paper of claim 1 in which said water comprises 75%> to 87% of the deinking solution. 21. The method of deinking paper of claim 1 in which the surfactant comprises l%>-3% of the deinking solution. 22. The method of deinking paper of claim 1 in which the solvent comprises 15%-20% of the deinking solution. 23. The method of deinking paper of claim 1 in which the deinking solution has a pH in the range of 6.5-7.5. 24. The method of deinking paper of claim 1 in which the solvent comprises glycol ether and an aromatic hydrocarbon. 25. The method of deinking paper of claim 24 in which said glycol ether is selected from the group consisting of ethylene glycol n-Butyl ether, diethylene glycol n-Butyl ether, ethylene glycol n-Butyl acetate and diethylene glycol n-Butyl acetate. 26. The method of deinking paper of claim 25 in which the aromatic hydrocarbon is selected from the group consisting of ethyl 4-methoxybenzoate, ethyl 3- methoxybenzoate and 2-methoxybenzoic acid ethyl ether. 27. A system for deinking a sheet of paper by removing toner thereon comprising: means for wetting the sheet of paper with a non-toxic, water soluble deinking solution comprising; water, for wetting the sheet of paper to swell the fibers of said sheet, a water soluble surfactant for lowering the surface tension of said water to enhance wetting of the sheet with said water, and no more than two water soluble solvents for softening the toner, without dissolving the toner, and for breaking the bond between the toner and the sheet; means for removing the softened toner from the sheet, creating toner particles; means for heating the sheet to vaporize the deinking solution, removing the solution from the sheet; and means for calendering the sheet of paper to return the sheet to said predetermine dimensions for immediate reuse. 28. The system for deinking paper of claim 27 in which said water and said surfactant are in a 10:1 ratio in said deinking solution. 29. The system for deinking paper of claim 27 in which said surfactant is selected from the group consisting of Triton X-155, Triton X-305, Triton X-405 and BRD 2311. 30. The system for deinking paper of claim 28 in which said deinking solution further includes a solvent in a ratio of 3:10 to said water and surfactant. 31. The system for deinking paper of claim 30 in which said solvent is a C 12- C14 aliphatic saturated hydrocarbon. 32. The system for deinking paper of claims 30 in which said solvent is an ether. 33. The system for deinking paper of claims 30 in which said solvent is Diethylene Glycol n-Butyl Ether. 34. The system for deinking paper of claim 27 further comprising means for collecting the toner particles. 35. The system for deinking paper of claim 34 further comprising means for recycling the toner particles. 36. The system for deinking paper of claim 27 further comprising means for collecting the vapors produced by said heating. 37. The system for deinking paper of claim 36 in which said means for collecting the vapors includes means for condensing the collected vapors back to liquid deinking solution and means for recycling the condensed deinking solution. 38. The system for deinking paper of claim 27 in which said means for removing includes means for wiping the sheet to remove the toner particles. 39. The system for deinking paper of claim 38 in which said means for wiping includes a rotating coiled brush to remove the toner particles from the sheet. 40. The system for deinking paper of claim 39 in which said means for wiping further includes means for collecting the toner particles from said coiled brush. 41. The system for deinking paper of claim 40 in which said means for collecting the toner particles includes means for combing the coil brush to remove the toner particles from the brush. 42. The system for deinking paper of claim 41 in which said means for combing includes means for depositing the toner particles in a recovery compartment. 43. The system for deinking paper of claim 27 in which said means for heating includes means for blowing heated air on the sheet to dry the sheet. 44. The system for deinking paper of claim 43 in which the heated air has a temperature in the range of 60 °C to 70 °C. 45. The system for deinking paper of claim 27 in which said means for calendering includes means for feeding the sheet between heated rollers. 46. The system for deinking paper of claim 45 in which the rollers have a temperature in the range of 20°C to 60°C. 47. The system for deinking paper of claim 29 in which said water comprises 15% to 87%) of the deinking solution. 48. The system for deinking paper of claim 27 in which the surfactant comprises l%-3% of the deinking solution. 49. The system for deinking paper of claim 27 in which the solvent comprises 15%-20% of the deinking solution. 50. The system for deinking paper of claim 27 in which the deinking solution has a pH in the range of 6.5-7.5. 51. The system for deinking paper of claim 27 in which the solvent comprises glycol ether and an aromatic hydrocarbon. 52. The system for deinking paper of claim 51 in which said glycol ether is selected from the group ethylene glycol n-Butyl ether, diethylene glycol n-Butyl ether, ethylene glycol n-Butyl acetate and diethylene glycol n-Butyl acetate. 53. The system for deinking paper of claim 52 in which the aromatic hydrocarbon is selected from the group ethyl 4-methoxybenzoate, ethyl 3-methoxybenzoate and 2-methoxybenzoic acid ethyl ether.

Inventors: ASHU JAMES TABOT, BHATIA SUSHIL, PICHEL MAURICE, ASHU, JAMES, TABOT, BHATIA, SUSHIL, PICHEL, MAURICE
Applicants: DECOPIER TECHNOLOGIES INC, DECOPIER TECHNOLOGIES, INC.
Application year: 1999
Main classification: D21C5
IPC codes: B08B3, D21C5, D21H11, G03G21