JP2960229B2 - Decoloring method and decoloring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for erasing a toner image formed on a sheet using a photochemically erasable toner.

[0002]

2. Description of the Related Art In recent years, the recycling and recycling of used paper has been reviewed for the purpose of protecting nature, especially protecting forest resources and reducing waste in urban areas. As part of this, the reuse of used copy paper, printed matter, facsimile paper and the like that is no longer needed in a corporate office is being studied.

However, most of these papers are confidential documents inside the company, which are generally regarded as trade secrets. Therefore, it is extremely difficult to collect and reuse these papers outside the company. In addition, since the recorded and printed parts of printed and copied materials cannot be easily erased, they must be incinerated or crushed and disposed of.
It was thought that such recycling of papers was virtually impossible.

[0004]

The inventors of the present invention have conducted intensive studies in view of the above-mentioned prior art, and as a result, have found a near-infrared decoloring dye capable of absorbing and decoloring near-infrared rays. Developed toner using dyes
77725.

When electrostatic copying is performed using the toner, images and prints recorded on a sheet such as copy paper can be erased only by irradiating near infrared rays. Or, since printing can be performed, the sheet body can be reused, and when discarding a used sheet body, a recorded image, printing, etc. can be erased by irradiation with near-infrared light, There are many advantages, such as the ability to collect and recycle sheet bodies inside a company without leaking confidential matters to the outside.

However, the decoloring speed due to the irradiation of near-infrared rays alone is slow. For example, when decoloring the toner image on the entire recording paper of Japanese Industrial Standard A No. 4 size, at least 1
It takes several tens of seconds per sheet. That is, there is a problem that only a few sheets / minute of the decoloring process can be performed.

Accordingly, an object of the present invention is to solve the above-mentioned technical problems and to remarkably improve the erasing speed of a toner image formed on a sheet member.

[0008]

According to the present invention, there is provided a process of heating a toner image formed on a sheet by a photochemically erasable toner to at least a glass transition temperature of a binder resin of the toner. And a step of irradiating the heated toner with near-infrared rays.

The present invention also provides a heating means for heating a toner image formed on a sheet by a photochemically decolorable toner to at least a glass transition temperature of a binder resin of the toner, and a heating means for heating the toner image. And a near-infrared ray irradiating unit for irradiating the toner with near-infrared rays.

[0010]

According to the present invention, when a toner image formed by a photochemically decolorable toner formed on a sheet member is to be decolorized, the toner is heated by a heating means to at least a binder resin of the toner. Heat to above the glass transition temperature. Thereby, the thermal momentum of the molecules constituting the toner on the sheet increases. If the toner has a configuration that realizes a decoloring effect by absorbing near-infrared rays, the toner on the sheet body changes from a solid state to a state having rubber elasticity or a molten state by heating. When the toner in such a state is irradiated with near-infrared rays, the irradiation easily causes a decoloring effect.

In this manner, the sheet can be reused. Also, the decolorization is due to a chemical reaction,
The decolorization reaction of the present invention is irreversible. At this time, the heated toner is in a state in which its constituent molecules are excited, its appearance is in a state of at least rubber elasticity, and the chemical change of the toner that realizes decoloration by the irradiation of the near-infrared light is in a solid state. Is performed much more rapidly than in the case of, and the erasing speed can be improved. In addition, this decoloring reaction is realized by an irreversible chemical reaction, and the decolorized toner image on the sheet body is decolorized / colored depending on the ambient temperature, the presence or absence of normal white light, or chemical conditions. This prevents a situation in which a change or discoloration undesirably fluctuates.

Sheets that can be recycled in the present invention include, for example, recording paper, OHP films, magnetic cards, plastic sheets for display boards, and the like used in ordinary electrostatic photography, such as electrostatic copying used for office and business use. All possible papers,
In the case of decoloring a print on a plastic film, including a sheet body such as a plastic film, the heat distortion temperature of the plastic film needs to be higher than the glass transition temperature of the toner used.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The toner used in the present invention is a photochemically erasable toner, and is a erasable toner which erases color by absorbing near infrared rays. For details of a large number of composition examples of such a decolorizable toner, examples of other components constituting the toner such as a sensitizer, and how the decolorizing action of the toner of each composition example appears, see Japanese Patent Application No. 3-277725. Therefore, in the following embodiments, several examples of the decoloring toner will be described. The present invention is not limited to such an example of the present embodiment, but includes a wide variety of modifications in accordance with the spirit of the present invention.

Such a decolorizable toner is, for example, constituted by dispersing a dye and an organic boron ammonium salt in a styrene resin. The dye is represented, for example, by the following chemical formula 1 or chemical formula 2.

[0015]

Embedded image

[0016]

Embedded image

The styrene resin is widely used as a binder resin for toner. The dyes represented by the above-mentioned chemical formulas 1 and 2 are one of the cyanine-based dyes, and when coexisting with an organic boron ammonium salt, when irradiated with near-infrared light having a wavelength of around 820 nm, they absorb near-infrared light and become A reversible reaction occurs and the blue color disappears and becomes colorless. As this organic boron ammonium salt, for example, tetrabutylammonium nbutyltriphenylboron shown in the following formula 3 is used.

[0018]

Embedded image

In the following examples, S shown in Table 1 below is used.
Six types of decoloring toners 1 to S6 were prepared and used.

[0020]

[Table 1]

In the above Table 1, the symbols RE1 to RE3 are binder resins, for example, a styrene-acrylic resin is used, and RE1 is Hymer SBM-100 manufactured by Sanyo Chemical Industries, Ltd., which has a softening point. MP is 104 ° C,
Glass transition temperature TG is 60 ° C. RE2 is Hymer TB-1000 manufactured by Sanyo Chemical Industries, Ltd., which has a softening point MP of 145 ° C. and a glass transition temperature TG of 58 ° C.
It is. RE3 is Hymer S manufactured by Sanyo Chemical Industries, Ltd.
T-125, the softening point MP is 125 ° C, and the glass transition temperature TG is 50 ° C.

Symbols DY1 and DY2 are dyes, and DY1
Is a dye shown in Chemical Formula 1, and DY2 is a dye shown in Chemical Formula 2. The sensitizer in Table 1 is tetrabutylammonium nbutyltriphenylboron as an example of the organic boron ammonium salt shown in Chemical formula 3.
An example of the wax is a polypropylene wax manufactured by Sanyo Chemical Industries Co., Ltd., and the product name is Viscol 550P.

Each mixture of S1 to S6 in Table 1 was kneaded with a pressure mixer at a temperature of 120 ° C. for 15 minutes. Thereafter, the cooled and solidified product was pulverized by a jet mill, and then a particle size of about 5 to 20 μm and an average particle size of about 10 μm were obtained by a classifier. Next, a silica-based fine powder was added as an external additive to the toner 10.
0.5 parts by weight per 0 parts by weight was added and mixed with a Henschel mixer to prepare six types of toners. The external additive is
An example is silica R972 manufactured by Nippon Aerosil Co., Ltd. As described above, the external additive is to mix the toner with the above-described average particle diameter by a classifier and adhere to the toner surface, and has an action of aligning the charge polarity of the toner to a negative electrode or the like. And to prevent the toner from aggregating and solidifying.

As a carrier mixed with the toner of this embodiment, Cu-Zn ferrite was used. Specifically, FB-810 manufactured by Kanto Denka Kogyo Co., Ltd. was used. 95 parts by weight of this carrier and 5 parts by weight of the toner were placed in a polypropylene container and mixed at 50 rpm for 30 minutes to obtain a developer.

The recording paper used was a laser beam printer KX-P4420 manufactured by Kyushu Matsushita Electric Co., Ltd., which was printed on a copy paper No. V602 manufactured by Fuji Xerox Co., Ltd. as "TONER" with characters of about 4 mm square.

(Embodiment 1) An embodiment relating to a decoloring method In decoloring a toner image with a photochemically decolorable toner having the above-described configuration, the toner image is bound with the styrene resin or the like of the toner. Glass transition temperature T of resin
Heat to a temperature of G or higher. More preferably, the binder resin is heated to a temperature equal to or higher than the softening point MP and lower than the decomposition temperature of the binder resin, the near-infrared absorbing dye, the organic boron ammonium salt sensitizer, and the like constituting the toner. . When the binder resin is heated to a glass transition temperature TG or higher, the binder resin changes from a solid state to a state having rubber elasticity,
Above the softening point MP, it is in a molten state. In the present embodiment, the toner in such a state is irradiated with near-infrared rays having the above-mentioned wavelength using a light source. This increases the decoloring speed of the photochemically decolorable toner.

Hereinafter, the principle of achieving the above-described functions and effects by performing heating prior to irradiation with near infrared rays will be described. The inventor heated the photochemically decolorable toner as described above prior to near-infrared irradiation, and measured the surface temperature of the recording paper and the near-infrared irradiation time until complete decoloration. did.

FIG. 1 is a schematic diagram of a configuration used for performing such a measurement. This measurement was performed by installing the configuration shown in the figure in a dark room. In this configuration, a cylindrical heat-insulating cover 53 having an upper opening is hermetically mounted on the heater 33, and a transparent heat-resistant glass 54 is air-tightly fixed to the opening of the heat-insulating cover 53. Thus, an internal space 55 that is airtight with the outside is formed. The recording paper 6 on which the toner image made of the photochemically decolorable toner is formed is mounted on a support plate 52 made of a heat insulating material disposed on the heater 33, and the heater 3.
At 3, the recording paper 6 is heated. Above the recording paper 6, a light source 35 such as a halogen lamp is arranged.

That is, in this configuration, the air in the internal space 55 is heated by the heater 33, and the recording paper 6 is heated by the heated air. The temperature of the recording paper 6, that is, the internal space 55
Is measured by a thermometer 56 which penetrates the heat insulating cover 53 and protrudes into the interior space 55.

The procedure for erasing the toner on the recording paper 6 using the configuration shown in FIG. 1 is as follows. First, the air in the internal space 55 is heated by the heater 33 and the temperature of the internal space 55 is measured by the thermometer 56. Is a predetermined temperature. Internal space 55
When the temperature reached a predetermined temperature, the state was maintained for about 5 minutes, and then the light source 35 irradiated near infrared rays. The decolorizing toner and the recording paper used in the experiment were prepared by mixing the toners S1 to S6 in Table 1 with the above-described carrier to form a developer. Recording paper 6 printed using a beam printer was used.

The light source 35 is an aluminum-coated halogen lamp that generates near-infrared rays.
Irradiation was performed at a rating of 50W. The results of such measurements are shown in the graph of FIG. In this experimental example, the completion of the decoloring was determined by preparing 10 observers, and the minimum time when six out of the ten persons judged that the decoloring was completed was defined as the completion of the decoloring. Irradiation time. Also, the softening point MP of the toner
Is measured according to Japanese Industrial Standard JIS K-2207 (199
0) The ring and ball method was used, and the glass transition temperature was measured using a thermal analyzer (DSC) according to US Standard ASTM D3418-.
The measurement was performed using the measurement method specified in 82.

As can be seen from FIG. 2, there is a transition point Ta1 where the lamp irradiation time required for decoloring rapidly decreases around 50 to 60 ° C., and thereafter, the irradiation time gradually decreases with increasing temperature. And there is a second transition point Ta2 where the irradiation time rapidly decreases again at around 100 to 150 ° C.
The change point Ta1 is due to the glass transition temperature TG of the binder resin used for these toners, and the change point Ta2 is due to the softening point MP of the binder resin. That is, FIG. 2 shows that the decolorization reaction rapidly proceeds when the binder resin has a rubber elasticity state, and then the decolorization reaction in the rubber elastic state is saturated, and the binder resin is melted into a fluid state. This shows a phenomenon in which the decoloring action speeds up again.

From the above experimental results, as a decoloring method for improving the decoloring speed, a toner image formed by a photochemically decolorable toner formed on a sheet is used.
It can be seen that a decoloring method including at least a step of heating the toner at or above the glass transition temperature of the binder resin and a step of irradiating the heated toner with near-infrared light is effective.

(Embodiment 2) Embodiment relating to the erasing apparatus FIG. 3 is a sectional view of an erasing apparatus 60 according to an embodiment of the erasing apparatus of the present invention. In the present embodiment, the decoloring device 60 is
It has a heat insulating wall 61 made of a heat insulating material having a cavity inside, and has an endless belt 64 spanned between a pair of rollers 62 and 63 inside. A heater 65 is disposed in the space surrounded by the endless belt 64 and between the rollers 62 and 63.
Above the side opposite to 5, a plurality of pressing rollers 66 are arranged.

As shown in the plan view of FIG. 4, a plurality of pressing rollers 66 are arranged at intervals on a plurality of rotating shafts 67, and adjacent pressing rollers 66 are disposed between the pressing rollers 66. The pressing roller 66 attached to the shaft 67 faces. Above the pressing roller 66, a bar-shaped light source 68 such as a halogen lamp of 500W100V or the like is disposed as an example for generating light containing near infrared rays having a wavelength of 820 nm.

Further, the toner image on the recording paper 6 has rubber elasticity by being heated by the heater 65 or is melted on the endless belt 64, so that the toner adhering to the endless belt 64 is removed. A cleaning member 69 such as a metal blade that is in sliding contact with the belt 64 is disposed.

An irradiation unit 70 for irradiating the recording paper 6 with light containing near-infrared rays is provided downstream of the pressing roller 66 along the traveling direction A1 of the recording paper 6. Irradiation unit 70
A mounting table 71 on which the recording paper 6 is mounted and slides thereon, and a light source 72 having the same configuration as the light source 68 are disposed above the mounting table 71. With respect to the platform 71, the traveling direction A
A pair of fixing rollers 73 is disposed on the downstream side, and the decolored toner remaining on the recording paper 6 is nipped by the pair of fixing rollers 73 and stretched over the entire surface of the recording paper 6. Thus, the surface of the recording paper 6 is made relatively smooth. A pair of discharge rollers 74 is disposed downstream of the fixing roller 73 in the traveling direction A1 and discharges the recording paper 6 from which the toner image has been erased to the outside of the erasing device 60.

FIG. 5 shows an example in which heating and near-infrared irradiation are performed simultaneously when the recording paper 6 is subjected to a decoloring process. That is, the light source 35 for irradiating the near-infrared ray is disposed inside a roller 57 made of transparent glass, and a pair of rollers 58a and 58b are disposed close to the roller 57 and spaced from each other in the circumferential direction of the roller 57. You. Further, another roller 58c is arranged at an interval from the roller 57, and a belt 6 is attached to these rollers 58a, 58b, 58c.
4 is wound. Therefore, the rollers 58a, 58
The belt 64 between the rollers b is in contact with the transparent glass roller 57. The heater 33 is provided near the portion of the belt 64 that is in contact with the roller 57.

The recording paper conveyed from the direction of arrow A1 is conveyed while being sandwiched between the belt 64 and the roller 57.
Heated by the heater 33. At this time, the roller 57
The near-infrared ray is radiated to the recording paper via the roller 57 by the light source 35 in the inside, and the decoloring process is performed. The erased recording paper is transported in the direction of arrow A2.

In such an embodiment, the same effects as those described in the above embodiment can be achieved.

Further, the method and apparatus of the present invention are not limited to being applied to the toner contained in the developer of the electrostatic copying machine as in the above-described embodiment, but may be any of the dyes represented by Chemical Formula 1 or Chemical Formula 2.
Alternatively, the present invention can be applied to a decolorable ink for printing, stamping, or writing containing a wide variety of dyes. Further, the embodiment as the erasing device is not limited to the example of the erasing device 60 as the single device, but is provided inside other devices such as provided before and after a fixing unit of an electrostatic copying machine. Including examples.

[0042]

As described above, according to the present invention, the toner having rubber elasticity or molten state is irradiated with infrared rays using the near-infrared ray irradiating means. As a result, the toner becomes colorless and decolored. Thus, the recording paper can be reused. Further, the decoloration is due to a chemical reaction, and the decolorization reaction can be irreversible.

At this time, the heated toner is in a state of at least rubber elasticity, and the chemical change of the toner for decoloring by irradiation with the near-infrared rays is performed much more rapidly than in the case where the toner is in a solid state. Therefore, the erasing speed can be improved.

[Brief description of the drawings]

FIG. 1 is a decoloring apparatus used in an experiment on a decoloring method of the present invention.

FIG. 2 is a graph showing the results of the experiment.

FIG. 3 is a sectional view of an embodiment 60 of the decoloring apparatus of the present invention.

FIG. 4 is a plan view showing a configuration of a roller 66 of the decoloring apparatus 60 shown in FIG.

FIG. 5 is a sectional view showing another embodiment of the decoloring apparatus of the present invention.

[Explanation of symbols]

 6 Recording paper 35, 68, 72 Light source 33, 65 Heater 57 Glass roller 59 Heating unit 60 Decoloring device 64 Endless belt 66 Press roller 70 Irradiation unit

Continuation of the front page (72) Inventor Katsumi Murofushi 5-1 Ogimachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Chemical Research Laboratory, Wado Electric Works Co., Ltd. (72) Kiichi Hosoda 5-1 Ogimachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Akira (56) References JP-A-4-356085 (JP, A) JP-A-62-14163 (JP, A) JP-A-60-89163 (JP, A) JP-A-1 102489 (JP, A) JP-A-5-61246 (JP, A) JP-A-5-51548 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 21/00 570 -578 B41J 29/26 B41J 29/36 G03G 9/00-9/18

Claims (2)

(57) [Claims] 1. A step of heating a toner image formed on a sheet by a photochemically erasable toner to at least a temperature higher than a glass transition temperature of a binder resin of the toner; Irradiating infrared rays. 2. A heating means for heating a toner image formed by photochemically decolorable toner formed on a sheet body to at least a glass transition temperature of a binder resin of the toner, and A decoloring device comprising near-infrared irradiation means for irradiating near-infrared light.