JP5487901B2 - Printing method of decolorizable toner - Google Patents

Description

  The present invention relates to a method for printing a decolorable toner, and more particularly to a method for printing a decolorable toner that improves the apparent color erasability.

  In recent years, there has been a call for saving paper resources as part of protecting the global environment. In view of this, for the purpose of reusing paper resources, various methods for performing image formation again by removing or erasing the image of the recording paper formed with toner are considered.

  In order to remove and erase such an image, a processing solution for removing toner is applied to the paper surface on which the image is formed, and the image is removed by heating, or the image forming surface of the paper is polished. There is a method of scraping off the toner image. However, these methods are troublesome because the paper to be reused is easily damaged.

  As another method, when forming an image, a method is known in which an image is previously printed on a recording paper with a decolorable toner (hereinafter also referred to as printing) and the image is erased by heating and light irradiation. Yes.

  As an example of this, a function for performing development, transfer, and fixing using a decolorable toner to perform printing on a recording sheet, and a decoloring toner character or image printed on a recording sheet with decoloring light. An image forming apparatus having a function of erasing and erasing by irradiation has been proposed (for example, Patent Document 1).

  By the way, usually, the printed matter does not necessarily print a uniform image on the print area. For example, in general, large fonts, small fonts, thick fonts, and thin fonts are mixed. Also, in the case of images and photographs, there is a partial shading.

  In general, a portion with a large print area printed on a recording paper or a portion with a high density has good visibility, but on the other hand, there is a problem that the apparent color erasability is poor.

  FIG. 8A is a diagram showing an example of printing with a conventional erasable toner, and FIG. 8B is a diagram showing an example of erasing the printed characters and images. In FIG. 2B, the erased portion is indicated by a broken line for easy understanding.

  As shown in FIG. 8 (a), on the recording paper 1, a character string 2 of ABC... E of a relatively small font is printed at the center. A character string 3 of ABC... E of a slightly larger (medium size) font is printed above and below the character string 2. In addition, a character string 4 of a relatively large font ABC... E is printed above and below them, and a dark image 5 is printed above and below them.

  When the printing surface of the recording paper 1 in FIG. 8A is erased as shown in FIG. 8B, the character string 2 of the small font and the character string 3 of the medium font are well erased in actual appearance. However, the character string 4 and the dark color image 5 of the large font appear to be insufficiently decolored in comparison with the decolored portions of the character string 2 and the character string 3.

  This phenomenon occurs because the color erasing itself is performed mechanically evenly, but the human eye has a characteristic that a large area is conspicuous and a small area is inconspicuous. It is thought that.

Japanese Patent Laid-Open No. 08-152823

  The above-described problem that the portion having a large printing area or the portion having a high density looks worse in color erasing than the other portions is that printing with a decolorable toner is performed by the method of the prior art disclosed in Patent Document 1. Even if the color disappears, it cannot be avoided.

  As a method for solving this problem, it is easy to think of strengthening the decoloring setting conditions. However, if the decoloring setting conditions are strengthened and the heat and light for decoloring are increased, the decoloring energy will become excessive and cause yellowing in areas with low density or white paper, resulting in paper quality. The problem of lowering occurs.

  In addition, since such a decoloring setting condition requires excessive energy for decoloring, there arises a problem that it is contrary to energy saving and economic efficiency that should originally be the purpose of this type of apparatus.

  In order to solve the above problems, the present invention has an apparent decoloring property that the decolored surface of the recording paper appears to be uniformly decolored regardless of the difference in printing area and density after decoloring. It is an object of the present invention to provide a printing method for an erasable toner that is improved.

The method of printing decolorizable toner of the present invention, when printing images on a print medium, the mixing amount and color density low not decolorizable toner weight loss of decolorizable dye, the color density have a low using two kinds of decolorizable toner of increasing amounts of color density is not high decolorizable toner mixing amount of decolorizable decolorizable dye than the toner, to the image to be printed on the print medium, of the image area is large and prints a portion having a high concentration in the color density have a low decolorizable toner, printing the other portions in the color density is not high decolorizable toner, as configured.

Further, the method of printing decolorizable toner of the present invention, when printing the images on the print medium, using a plurality of types of decolorizable toner color density are different from each other by changing the mixing amount of the decolorizable dye, wherein to generate the image to be printed on the print medium, the area is large and a high concentration portion of the image to the smaller and the concentration is low part area, higher decolorizable color density from a low color density decolorizable toner It is configured to sequentially switch to toner and print.

  The present invention has an effect that it is possible to provide a printing method of a decolorizable toner that improves the apparent decoloring property after decoloring regardless of the difference in printing area and density.

It is sectional drawing which shows typically the internal structure of the image forming apparatus with a decoloring function which concerns on Example 2 of this invention. It is a circuit block diagram including the control apparatus of the image forming apparatus with a color erasing function according to Embodiment 2 of the present invention. As an example, a diagram illustrating a printing method using decoloring toner when printing print data including a small font character string, a medium font character string, a large font character string, and a dark color image shown in FIG. It is. FIG. 10 is a diagram illustrating a printing method for printing with three types of density, dark, medium, and light, using a decolorizable toner according to Example 3 of the invention. FIG. 10 is a cross-sectional view schematically illustrating an internal configuration of an image forming apparatus with a color erasing function according to a modification example of Example 3. FIG. 10 is a cross-sectional view schematically illustrating an internal configuration of an image forming apparatus with a color erasing function according to a fourth embodiment. FIG. 7 is a diagram illustrating an example in which print data similar to that illustrated in FIG. 3 is printed with a decolorable toner of the image forming apparatus with a decoloring function illustrated in FIG. 6. (a) is a diagram showing an example of printing with a conventional erasable toner, and (b) is a diagram showing an example of erasing the printed characters and images.

  Hereinafter, embodiments of the present invention will be described in detail.

<Method for producing decolorizable toner>
First, a method for producing a decolorizable toner used in the present invention will be described as Example 1. First, 1.5 parts by mass of infrared photosensitive dye “IRT” (manufactured by Showa Denko) having sensitivity at 817 nm, 4 parts by mass of organic boron compound decolorizer “P3B” (manufactured by Showa Denko), polyester binder for toner 90.5 parts by mass of resin (manufactured by Kao), 1.5 parts by mass of negative charge control agent “LR-147” (manufactured by Nippon Carlit), 2.5 parts by mass of Carnauba WAX No. 1 powder (imported by Kato Yoko Co., Ltd.) Into a Henschel mixer (Mitsui Mine) and mix.

  Subsequently, the above mixture is melt-kneaded with a twin-screw kneader. The kneaded material thus obtained is roughly crushed with a Rotoplex (manufactured by Hosokawa Micron) to obtain a coarsely crushed material. The resulting coarsely crushed material is pulverized by an impact pulverizer so that the average particle size becomes 9 μm.

  One part by mass of silica “R972” (manufactured by Nippon Aerosil Co., Ltd.) as an external additive is added to 100 parts by mass of the pulverized product obtained by this pulverization, and mixed with a Henschel mixer to obtain a decolorizable toner. This decolorizable toner is manufactured so that the glass transition point is 50.3 ° C. and the softening point is 106 ° C.

<Configuration of image forming apparatus and image formation>
FIG. 1 is a cross-sectional view schematically showing an internal configuration of an image forming apparatus with a color erasing function according to Embodiment 2 of the present invention. As shown in FIG. 1, the image forming apparatus 10 with a color erasing function includes an endless transfer belt 12 extending in the horizontal direction at the center of the inside of the main body housing 11.

  The transfer belt 12 is stretched around a driving roller 13 and a driven roller 14 while being stretched by a tension mechanism (not shown), and is driven by the driving roller 13 to circulate in a counterclockwise direction indicated by an arrow a in the figure. To do.

  The photosensitive drums 16 (16a, 16b) of the two image forming units 15 (15a, 15b) are disposed in contact with the upper circulation movement surface of the transfer belt 12. The photosensitive drum 16 is provided with a cleaner, an initialization charger, an optical writing head, a developing roller, and the like that are not shown in the vicinity so as to surround the peripheral surface.

  The developing roller is disposed in the side opening of the toner container 17 (17a, 17b). The toner container 17 contains decolorable toner R (Ra, Rb). The decolorizable toner Ra is the decolorizable toner described in Example 1, and the decolorable toner Rb is obtained by slightly reducing the mixing density of the infrared photosensitive dye “IRT” and slightly reducing the color density.

  The developing roller carries a thin layer of the decolorizable toner R contained in the toner container 17 on the surface, and is formed on the peripheral surface of the photosensitive drum 16 by the optical writing head. The image of the decolorizable toner R is developed on the image.

  A primary transfer roller 18 (18a, 18b) is pressed against the lower portion of the photosensitive drum 16 via the transfer belt 12 to form a primary transfer portion. A bias voltage is supplied to the primary transfer roller 18 from a bias power source (not shown).

  The primary transfer roller 18 applies a bias voltage supplied from a bias power source to the transfer belt 12 at the primary transfer portion, and transfers an image of the decolorizable toner R developed on the peripheral surface of the photosensitive drum 16 to the transfer belt. 12 is transferred.

  A secondary transfer roller 19 is in pressure contact with the driven roller 14 across the right end portion of the transfer belt 12 shown in the drawing via the transfer belt 12 to form a secondary transfer portion. A bias voltage is supplied to the secondary transfer roller 19 from a bias power source (not shown).

  The secondary transfer roller 19 applies a bias voltage supplied from a bias power source to the transfer belt 12 in the secondary transfer portion, and the image of the decolorable toner R that is primarily transferred to the transfer belt 12 is transferred to the image forming conveyance path. Then, the image is transferred to the recording medium 22 conveyed along the line 21 from below in the drawing.

  The recording medium 22 is stacked and accommodated in a recording medium accommodation unit 23 composed of a paper feed cassette or the like, taken out one by one by a paper feed roller (not shown), and sent to the paper feed conveyance path 24. Then, the toner is further conveyed through the image forming conveyance path 21, and the image of the decolorable toner R is transferred while passing through the secondary transfer portion.

  The recording medium 22 that has passed the secondary transfer portion while transferring the image of the decolorizable toner R is conveyed along the fixing conveyance path 25 to the fixing unit 26. The heating roller 27 and the pressing roller 28 of the fixing unit 26 sandwich the recording medium 22 and convey it while applying heat and pressure.

  As a result, the image of the decolorable toner R that has been secondarily transferred is fixed on the paper surface, and the recording medium 22 is further conveyed by the heating roller 27 and the pressing roller 28 to be formed on the upper surface of the main body device casing 11. The paper is discharged to the paper discharge tray 29.

<Configuration of device body and erasing mechanism>
By the way, a recording medium 22 on which an image of the decolorable toner R is formed between the recording medium storage unit 23 and the secondary transfer unit, that is, between the paper feeding conveyance path 24 and the image forming conveyance path 21. A color erasing unit 31 for erasing the image is arranged.

  The erasing unit 31 efficiently erases the image of the erasable toner R to be erased from the back surface of the image forming surface and the erasable heater roller 32 and the heated image of the erasable toner R. It comprises a decoloring LED head 33 for color.

  As described above, the decolorizable toner (R) used in this example is manufactured such that its glass transition point is 50.3 ° C. and its softening point is 106 ° C.

  The erasing heater roller 32 of the erasing unit 31 shown in FIG. 1 incorporates a halogen lamp. The wavelength distribution of the halogen lamp is wide and includes a wide wavelength distribution of near infrared rays, so that it is suitable as a heat source for heat radiation.

  In this example, the temperature of the heat radiation of the halogen lamp can be varied, and the heating temperature for the paper surface to be decolored can be set in the range of 50 ° C to 100 ° C. This temperature range is a range in which the heating temperature for decolorization can be set to a range that is higher than the glass transition point of the decolorable toner and lower than the softening point.

  Further, the decoloring LED head 33 in this example is formed of an LED array. Since LEDs have a very narrow wavelength distribution, there is very little generation of light with a wavelength unnecessary for decoloring depending on the selection of the LED, that is, light with a wavelength distribution with good decoloring efficiency is emitted. LED to be selected can be selected.

<Control device>
FIG. 2 is a circuit block diagram including the control device of the image forming apparatus 10 with the color erasing function. As shown in FIG. 2, the circuit block has a CPU (central processing unit) 35 as a center, and an interface controller (I / F_CONT) 36 and a printer controller (PR_CONT) 37 are connected to the CPU 35 via data buses. ing. A printer printing unit 38 is connected to the PR_CONT 37.

  Connected to the CPU 35 are a read only memory (ROM) 39, an electrically erasable programmable ROM (EEPROM) 41, an operation panel 42 of the main body operation unit, and a sensor unit 43 to which outputs from sensors arranged in the respective units are input. Has been. A system program is stored in the ROM 39, and the CPU 35 performs processing by controlling each unit in accordance with the system program.

  That is, in each unit, first, the I / F_CONT 36 converts print data supplied from a host device such as a personal computer into bitmap data and develops it in the frame memory 44. In the frame memory 44, a storage area corresponding to the decolorizable toner (R) is set, and data of the decolorizable toner image is developed in this storage area.

  The data expanded in the frame memory 44 is output to the PR_CONT 37, and is output from the PR_CONT 37 to the printer printing unit 38.

  The printer printing unit 38 is an engine unit, and under the control of the PR_CONT 37, a rotational drive system including the photosensitive drum 16, the primary transfer roller 18 and the like shown in FIG. 1, initialization not shown in FIG. A drive output to a process load such as an applied voltage of an image forming unit 15 having a driven portion such as a charger or an optical writing head is controlled.

  Further, the printer printing unit 38 controls the belt driving unit 45 that controls the vertical movement of a belt position control mechanism (not shown) of the transfer belt 12, the conveyance that controls the transfer belt 12 and a conveyance belt (not shown) of each conveyance path. The driving output to the erasing driving unit 47 that controls the belt driving unit 46 and the erasing unit 31 is controlled.

  Then, the image data of the decolorizable toner (R) output from the PR_CONT 37 is supplied from the printer printing unit 38 to the optical writing head in which the image forming unit 15 shown in FIG. 1 is omitted.

<Printing method of decolorizable toner>
FIG. 3 shows, as an example, color erasing when printing print data including the small font character string 2, the medium font character string 3, the large font character string 4, and the dark color image 5 shown in FIG. FIG. 6 is a diagram for explaining a printing method using a conductive toner R (Ra, Rb).

  In this example, the control device of FIG. 2 converts the print data supplied from the host device into bitmap data and develops it in the frame memory 44 in the above-described control at the time of image formation. Determine the size of the unit image.

  That is, when the individual print portions are relatively small like the characters of the small font character string 2 and the medium font character string 3, these individual characters are separated as small print portions, and the small font character string 2 and the medium font character are separated. The paper surface consisting of column 3 is set as a small print area 51 as an assembly of small print portions.

  Further, when the individual print portions are relatively large like the large font character string 4 and the dark color image 5, these individual print portions are separated as large print portions, and the large font character string 4 and the dark color image 5 are separated. Is set as a large print area 53 as an aggregate of large print portions.

  The small print area 51 is printed with the normal density erasable toner Ra, and the large print area 53 is printed with the erasable toner Rb having a slightly reduced color density. Then, the toner is fixed and discharged onto the discharge tray 29.

  Although the fixed paper surface is not particularly illustrated, although the large print area 53 is printed at a slightly lower density compared to the small print area 51 where the print density is high and clearly visible, Since the printed portion is wide, it can be clearly seen even if the density is low, and even if it is aligned with the small print area 51, the entire paper surface appears to be printed with an almost uniform density with no sense of incongruity.

  When this printed matter is returned to the recording medium accommodating portion 22, sent out to the paper feed conveyance path 24, and erased by the erasing portion 31, the small printing area 51 has small individual printing portions, although not particularly shown. It is well erased. Since the large print area 53 has a low print density, it is also well erased, and the entire paper surface appears to be uniformly erased.

  In the first embodiment, the print area is divided into two types and printed with two types of density, but the density is not limited to two types. You may make it print by the density of 3 types of dark middle and light.

  FIG. 4 is a diagram for explaining a printing method for printing with three types of density of dark, medium, and light colors using the decolorizable toner according to the third embodiment. In the third embodiment, the method for producing the decolorable toner, the configuration of the apparatus main body, the basic operation for image formation, the decoloring mechanism, and the configuration of the control apparatus are the same as those in the first and second embodiments.

  FIG. 4 shows, as an example, a case where the same print data as shown in FIG. 3 is printed with decoloring toner R (Ra, Rb) at three types of density, dark, medium and light.

  Also in this example, when the print data is converted into bitmap data and expanded in the frame memory 44, the control device of FIG. 2 first determines the size of the character font and the size of the unit image.

  That is, when the individual print portions are relatively small like the characters of the small font character string 2, these individual characters are separated as small print portions, and the paper surface composed of the small font character strings 2 is aggregated of the small print portions. As a small print area 51.

  If each printed portion is slightly larger than the characters of the small font character string 2 as in the medium font character string 3, these individual characters are separated as medium printed portions, and the paper surface comprising the medium font character string 3 is separated. The middle printing area 52 is set as a collection of middle printing portions.

  Further, when the individual print portions are relatively large like the large font character string 4 and the dark color image 5, these individual print portions are separated as large print portions, and the large font character string 4 and the dark color image 5 are separated. Is set as a large print area 53 as an aggregate of large print portions.

  The small print area 51 is printed with the normal density erasable toner Ra, and the medium print area 52 is printed with the erasable toner Ra dispersed in half the number of pixels, and the rest Is printed with a low-density decolorable toner Rb, and the large print area 53 is printed only with a low-density decolorable toner Rb, and is fixed by the fixing unit 26 and discharged. The paper is discharged to 29.

  Although the fixed paper surface is not particularly shown, the medium print area 52 is slightly thinner and the large print area 53 is printed at a lower density than the small print area 51 where the print density is high and clearly visible. Since the individual print portions are sequentially wider than the small print area 51, the entire paper surface can be read with a substantially uniform feeling without any sense of incongruity.

  When this printed matter is returned to the recording medium accommodating portion 22, sent to the paper feeding and conveying path 24, and erased by the erasing portion 31, the erasing portion 31 is not particularly shown. It appears to be evenly erased.

<Modification of Example 3>
FIG. 5 is a cross-sectional view schematically illustrating an internal configuration of an image forming apparatus with a decoloring function according to a modification of the third embodiment. In the image forming apparatus 50 with a color erasing function of this example, one image forming unit 15 is provided more than the image forming apparatus 10 with a color erasing function shown in FIG.

  That is, between the image forming unit 15a containing the dark-color erasable toner Ra and the image forming unit 15b containing the light-density erasable toner Rb as in the case of FIG. An image forming unit 15ab is disposed to accommodate the functional toner Rab. The other components are the same as those shown in FIG.

  In FIG. 5, the medium-density decolorable toner Rab of the image forming unit 15ab is, for example, a decolorable toner obtained by mixing the decolorable toner Ra and the decolorable toner Rb in half. The small print area 51 of the image data shown in FIG. 4 is printed by the image forming unit 15a, the middle print area 52 is printed by the image forming unit 15ab, and the large print area 53 is printed by the image forming unit 15b. Even if comprised in this way, the effect similar to Example 3 is acquired.

  FIG. 6 is a cross-sectional view schematically illustrating an internal configuration of the image forming apparatus with a decoloring function according to the fourth embodiment. In the image forming apparatus 55 with the color erasing function of this example, only one image forming unit 15a is accommodated as the image forming unit containing the normal density erasable toner Ra. The other components are the same as those shown in FIG.

  FIG. 7 is a diagram showing an example in which data is printed with the erasable toner Ra of the image forming apparatus 55 with the erasing function shown in FIG. 6 by the same printing as shown in FIG. As shown in FIG. 7, the small print area 51 is normally printed with the erasable toner Ra. The individual print portions of the large print area 53 are printed in a mesh-like print mode.

  Thus, even if the large print area 53 is thinned by mesh-like solid print, the individual print areas are wide (large), so that they can be clearly seen in the same manner as the small print areas 51. When the color is erased by the color erasing unit 31, the mesh-like paint is well erased because the amount of toner is small. In this case as well, the color is well erased as a whole, and the entire paper surface is erased uniformly. Looks like.

  Of course, if the size of the mesh is adjusted according to the size of the print area, it is possible to deal with three types of dark, medium, and light print areas, and it is possible to cope more finely.

  The present invention can be used in a printing method of a decolorizable toner that improves the apparent decoloring property.

DESCRIPTION OF SYMBOLS 1 Recording paper 2 Small font character string 3 Medium size font character string 4 Large font character string 5 Dark color image 10 Image forming apparatus with a decoloring function 11 Main body apparatus housing | casing 12 Transfer belt 13 Drive roller 14 Followed roller 15 (15a, 15ab, 15b) Image forming unit 16 (16a, 16b) Photosensitive drum 17 (17a, 17b) Toner container R (Ra, Rb) Erasable toner 18 (18a, 18b) Primary transfer roller 19 Secondary transfer roller 21 Image forming conveyance Path 22 recording medium 23 recording medium accommodating section 24 paper feed transport path 25 fixing transport path 26 fixing section 27 heating roller 28 pressure roller 29 paper discharge tray 31 color erasing section 32 color erasing heater roller 33 color erasing LED head 35 CPU (central processing unit)
36 Interface Controller (I / F_CONT)
37 Printer Controller (PR_CONT)
38 Printer printing section 39 ROM (read only memory)
41 EEPROM (electrically erasable programmable ROM)
42 Operation Panel 43 Sensor Unit 44 Frame Memory 45 Belt Drive Unit 46 Conveyor Belt Drive Unit 47 Decoloring Drive Unit 50 Decoloring Function Image Forming Device 51 Small Printing Area 52 Medium Printing Area 53 Large Printing Area 55 Image Formation With Decoloring Function apparatus

Claims (2)

When printing an image on a print medium,
A decolorizable toner having a low color density with a reduced amount of the decolorizable dye and a decolorizable toner having a higher color density with an increased amount of the decolorizable dye than the decolorizable toner having a low color density Using two types of decolorizable toner,
For the image to be printed on the print medium, a portion having a large area and a high density is printed with the decolorizable toner having a low color density, and the other portion is a decolorable toner having a high color density. Print with
A method for printing a decolorizable toner. When printing an image on a print medium,
Using different types of decolorizable toners with different color densities by changing the amount of decolorizable dyes mixed,
For the image to be printed on the printing medium, from a decolorizable toner having a low color density to a color erasability having a higher color density from a portion having a large area and a high density to a portion having a small area and a low density. Switch to toner sequentially and print,
A method for printing a decolorizable toner.