JP7153225B2 - image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

Conventionally, based on input image information, a color toner image made of yellow, magenta, and cyan color toners and a special toner image made of special toner are formed on the same recording medium, and the color toner image and the special toner image are formed. An image forming apparatus is known that forms an image by fixing a toner onto the recording medium by a fixing means.

For example, Japanese Patent Application Laid-Open No. 2002-200001 discloses an image forming apparatus using toner that absorbs light in the invisible region, such as infrared absorbing toner and fluorescent toner, as a special toner. In this image forming apparatus, when forming a secret image and a concealment image that conceals the secret image on a recording medium using infrared absorbing toner or the like, the total amount of toner (unit on the recording medium) used for one image formation is The total amount of the area ratio of the toner within the area (the total amount of toner in the case of a solid image of one color is 100%) is suppressed from exceeding a predetermined upper limit. Specifically, when all types (four types) of toner are used, the maximum total toner amount is 400%, but the upper limit of the total toner amount is set to about 230% due to poor fixing. Therefore, for the confidential image and the concealed image, the image forming operation including the fixing process is divided into a plurality of times so that the total amount of toner is equal to or less than the upper limit value, such as using two types of toner per time.

In a conventional image forming apparatus that forms an image using a special toner such as an infrared absorbing toner and a color toner, in order to suppress defective fixing, the image forming operation including the fixing process is divided into a plurality of times as described above. to run. Therefore, when forming an image using special toners and color toners, there is a problem that it takes more time to form an image than when forming an image without using a special toner (when the image forming operation is performed once). rice field.

In order to solve the above-described problems, the present invention provides a color toner image made of at least one of yellow, magenta, and cyan color toners and an infrared light absorbing toner image made of infrared light absorbing toner on the same recording medium. and fixing the color toner image and the infrared light absorbing toner image on the recording medium by a fixing means to form an image, wherein the color toner image and the infrared light absorbing toner image are In the case of the special image forming operation, the amount of color toner per unit area on the recording medium is higher than that in the normal image forming operation of forming the same color toner image without forming the infrared light absorbing toner image. control means for performing toner amount suppression control to reduce the amount of toner, wherein the infrared light absorbing toner image is formed closer to the recording medium than the color toner image on the recording medium, and the infrared light absorbing toner is formed on the recording medium side relative to the color toner image; , having transparency and having a weight average particle diameter of 5 μm or more and 7 μm or less .

According to the present invention, it is possible to shorten the time required to form an image using infrared light absorbing toner and color toner.

1 is an explanatory diagram showing the overall configuration of a printer according to an embodiment; FIG. FIG. 2 is a block diagram related to main controls in the printer of the embodiment; 4 is a flow chart showing the flow of image forming operation in the embodiment. 4(a) to 4(d) are schematic diagrams showing states of toner images obtained by superimposing an IR toner image and each color toner image of Y, M, and C. FIG. FIG. 4 is an explanatory diagram showing an example of total toner amount regulation processing according to the embodiment; FIG. 7 is an explanatory diagram showing another example of total toner amount regulation processing according to the embodiment; FIG. 9 is an explanatory diagram showing still another example of total toner amount regulation processing according to the embodiment; FIG. 9 is an explanatory diagram showing still another example of total toner amount regulation processing according to the embodiment; (a) is a schematic diagram of an example in which two-color toner images of Y and M are superimposed on an IR toner image. (b) is a schematic diagram of an example in which only the M toner image is superimposed on the IR toner image. FIG. 10 is a diagram showing a pattern example of only a color toner image; FIG. 11 is a view showing an example of an image in which the pattern example shown in FIG. 10 is superimposed on an IR toner image; FIG. 8 is a diagram showing another example of an image in which a color image is superimposed on an IR toner image;

An embodiment in which the present invention is applied to a color printer (hereinafter referred to as "printer"), which is an image forming apparatus, will be described below with reference to the drawings.
In this embodiment, as an example, the present invention is applied to an image forming apparatus with four stations or less. In addition, the image forming apparatus, based on the input image information, can generate a color toner image made of at least one color toner of yellow (Y), magenta (M), and cyan (C) and a special toner image made of special toner. are formed on the same recording medium, and the color toner image and the special toner image are fixed on the recording medium by a fixing means to form an image. Therefore, in addition to printers, copiers and facsimiles alone, or multifunction machines having at least two functions of printers, copiers, facsimiles, and scanners may be used. Also, the color toner may be a combination of multiple colors of yellow, magenta, and cyan. Further, for example, a color toner image in which yellow, magenta, and cyan are superimposed to express black is a color toner image.

The printer of this embodiment uses, as the special toner, a special color toner that forms an image that is difficult to visually recognize on a recording medium. For example, for the purpose of preventing illegal copying, such special color toners are used to form images that are difficult to recognize visually, such as invisible patterns and background patterns, on a recording medium together with normal images using color toners, and to add additional information to the images. used to embed the Special color toners include transparent infrared light absorbing toners and transparent fluorescent toners that fluoresce when exposed to ultraviolet rays. and emits light of The spot color toner (non-visible toner) is an image formed by toner having higher transparency under visible light than normal color toner. , light emission, color development, etc. are performed to facilitate visual recognition. As the special color toner, it is desirable to use a transparent toner whose color development is suppressed under visible light. It also contains less pigment than normal color toners.

Note that the special toner is at least a color other than yellow, magenta, cyan, and black, or a transparent toner. Here, white, metallic, etc. are also included.

This embodiment will be described using an example in which an infrared light absorbing toner is used as the spot color toner. In the following description, the reference numerals for each toner for each member are "Y" for yellow toner (Y toner), "M" for magenta toner (M toner), "C" for cyan toner (C toner), and infrared light absorption. As the toner (IR toner), "IR" is used.

First, the overall configuration and operation of the printer according to this embodiment will be described.
FIG. 1 is an explanatory diagram showing the overall configuration of the printer according to this embodiment.
The printer of this embodiment comprises an image forming section 1, a transfer section 2, a recording medium supply section 3, a fixing section 4, a recording medium discharge section 5, a control section 30, an image formation control section 40, mainly composed of

The image forming section 1 is provided with four process units 6Y, 6M, 6C, and 6IR as image forming units. Each of the process units 6Y, 6M, 6C, and 6IR has the same configuration except for the type of toner used. In this embodiment, since a process unit using black (K) toner is not provided, color images and monochrome images are formed using only Y, M, and C color toners. K process units may be added, but in that case, there is a drawback that the apparatus becomes large.

Alternatively, the IR process unit 6IR may be detachable, and the K process unit may be attached instead of the IR process unit. In this case, when image formation is performed without using IR toner, a color image or a monochrome image is formed using Y, M, and C color toners and K toner by installing a K process unit. can do.

Also, all the process units may be detachable so that the mounting positions of the process units can be interchanged. In this case, by changing the positions of the IR process units, it is possible to appropriately change the positional relationship (the positional relationship in the toner image stacking direction) between the IR toner image and each color toner image on the recording medium.

In this embodiment, each of the process units 6Y, 6M, 6C, and 6IR includes a photoreceptor 7 as a latent image bearing member for carrying a latent image, a charging roller 8 as charging means for charging the surface of the photoreceptor 7, It comprises a developing device 9 as developing means for developing the latent image on the photoreceptor 7 and a photoreceptor cleaning device 10 as latent image carrier cleaning means for cleaning the surface of the photoreceptor 7 . An exposure device 11 as a latent image forming means for forming a latent image on the surface of each photoreceptor 7 is provided at a position facing each photoreceptor 7 . In this embodiment, an LED unit is used as the exposure device 11, but a laser beam scanning system using a laser diode may be used.

The transfer unit 2 includes an endless intermediate transfer belt 12 as an intermediate transfer member onto which the toner image on the photoreceptor 7 is transferred, and a primary transfer means for primarily transferring the image on the photoreceptor 7 to the intermediate transfer belt 12 . a plurality of primary transfer rollers 13, a secondary transfer roller 14 as secondary transfer means for secondary transfer of the toner image transferred on the intermediate transfer belt 12 onto a recording medium, and the surface (outer peripheral surface) of the intermediate transfer belt 12. A belt cleaning device 17 is arranged as an intermediate transfer member cleaning means for cleaning the intermediate transfer member.

The intermediate transfer belt 12 is stretched between a drive roller 15 and a driven roller 16, and is circulated (rotated) as the drive roller 15 rotates. Each primary transfer roller 13 is arranged so as to press the intermediate transfer belt 12 against each photoreceptor 7 . As a result, a primary transfer nip is formed at the contact point between the intermediate transfer belt 12 and each photoreceptor 7 , where the image on each photoreceptor 7 is transferred to the intermediate transfer belt 12 . On the other hand, the secondary transfer roller 14 is arranged so as to contact the portion of the intermediate transfer belt 12 wound around the driving roller 15 . A secondary transfer nip is formed where the secondary transfer roller 14 and the intermediate transfer belt 12 contact each other, where the image on the intermediate transfer belt 12 is transferred to a recording medium.

The recording medium supply unit 3 includes a paper feed cassette 18 as a recording medium containing unit for containing paper P as a recording medium, and a paper feed roller as a recording medium feeding means for feeding the paper P from the paper feed cassette 18. 19, and a timing roller 20 serving as recording medium transport means for transporting the paper P fed by the paper feed roller 19 to the secondary transfer nip at a predetermined timing. The recording medium may be an OHP sheet, OHP film, cloth, or the like, in addition to paper. In addition to plain paper, paper includes thick paper, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), textured paper such as Japanese paper, tracing paper, and the like.

A fixing device 21 as fixing means for fixing an image on the paper P is arranged in the fixing section 4 . The fixing device 21 includes a fixing roller 22 as a fixing member heated by a heat source such as a heater, and a pressure roller 23 as a pressure member contacting the fixing roller 22 with a predetermined pressure to form a fixing nip. It is mainly composed of

The recording medium ejection unit 5 includes a paper ejection roller 24 as a recording medium ejection means for ejecting the paper P sent from the fixing device 21 to the outside of the apparatus, and a recording medium on which the paper P ejected by the paper ejection roller 24 is placed. A paper discharge tray 25 is arranged as a medium stacking portion.

The control unit 30 performs image processing on input image information from a reading device (scanner), a personal computer, or the like, and controls the entire printer.
Under the control of the control unit 30, the image formation control unit 40 controls image formation in each unit of the printer (image forming unit 1, transfer unit 2, recording medium supply unit 3, fixing unit 4, recording medium discharge unit 5, etc.). It controls the action.

In addition to the components described above, the printer of the present embodiment is equipped with a plurality of toner cartridges 26 as powder storage containers for storing toner, which is powder used for image formation. Each toner cartridge 26 contains toner of the same color as the toner in the corresponding developing device 9, and toner is replenished from the toner cartridge 26 when the toner in the developing device 9 falls below a predetermined amount. Further, the printer is equipped with a waste toner storage container 27 as a powder storage container separate from the toner cartridge 26 . Waste toner collected by the belt cleaning device 17 or the photoreceptor cleaning device 10 is stored in the waste toner storage container 27 .

Further, as shown in FIG. 1, the printer of this embodiment includes a cover member 101 for opening and closing the upper portion of the apparatus body (image forming apparatus body) 100 . The cover member 101 is vertically rotatable about a rotating shaft 103 provided in the apparatus main body 100 . A container holding member 102 that detachably holds four toner cartridges 26 is arranged below the cover member 101 . The container holding member 102 is vertically rotatable around another rotating shaft 104 provided in the apparatus main body 100 .

In the present embodiment, the process units 6Y, 6M, 6C, and 6IR produce an IR toner image (special toner image) made of IR toner on the recording medium more than a color toner image made of Y, M, and C color toners. The IR process unit 6IR is arranged on the most downstream side in the running direction of the intermediate transfer belt 12 so as to be formed on the recording medium side, and the color process units 6Y, 6M and 6C are arranged on the upstream side thereof. That is, on the intermediate transfer belt 12, a Y toner image, an M toner image, a C toner image, and an IR toner image are laminated in order from the belt side. The order from the medium side is IR toner image, C toner image, M toner image, and Y toner image.

By forming the IR toner image closer to the recording medium than the color toner image is, the IR toner image is hidden behind the color toner image, resulting in a decrease in visibility, making it easy to secure the confidentiality of the image by the IR toner image. However, where to place the IR process unit 6IR with respect to the color process units 6Y, 6M, and 6C can be set as appropriate. Further, as described above, when the mounting positions of the process units 6Y, 6M, 6C, and 6IR are interchangeable, the positions of the IR process units can be freely interchanged.

Further, in the printer of the present embodiment, the image density is adjusted by adjusting the adhesion amount of each toner of Y, M, C, and IR (toner adhesion amount per unit area). Specifically, the toner for detecting the toner adhesion amount of the test images (a plurality of toner patches formed to have different target densities) of each of Y, M, C, and IR toners formed on the intermediate transfer belt 12 An adhesion amount detection sensor is provided. Image forming conditions (image forming conditions) in each of the Y, M, C, and IR process units are adjusted based on the results detected by the toner adhesion amount detection sensor so that the desired toner adheres to the desired density. be done.

The toner adhesion amount detection sensor of this embodiment may be commonly used for each of the Y, M, C, and IR test images, or may be used separately for each of the Y, M, C, and IR test images. may be used for Further, the toner adhesion amount detection sensor of the present embodiment is an optical image density sensor, and acquires both specularly reflected light and diffusely reflected light to determine the toner adhesion amount of each test image (image density of the test image). to detect. The IR toner of the present embodiment forms an invisible image (an image that is difficult to see or an image that does not substantially have an absorption peak in the visible light region) after the fixing process. Since it is a visible image (image that can be seen with the naked eye or an image that substantially has an absorption peak in the visible light region), a toner adhesion amount detection sensor similar to those for C, M, and Y can be used. Regarding the IR toner test image, rather than acquiring only specular reflection light and detecting the toner adhesion amount of the test image, both specular reflection light and diffuse reflection light are acquired to detect the toner adhesion amount of the test image. Detecting the amount of toner can be realized with higher accuracy.

Next, the basic operation of the printer of this embodiment will be described.
When the image forming operation is started, each photoreceptor 7 is driven to rotate, and the charging roller 8 uniformly charges the surface of each photoreceptor 7 to a predetermined polarity. Next, based on input image information from a reading device (scanner), a personal computer, or the like, the exposure device 11 irradiates the charged surface of each photosensitive member 7 with LED light (laser light) to form a latent image (electrostatic latent image). do.

A latent image formed on each photosensitive member 7 is a latent image based on monochrome image information obtained by decomposing a desired full-color image into Y, M, and C color information. Specifically, using a color conversion/separation table for converting and decomposing the color information (RGB, YCM, etc.) of the input image information into the color information (YMC) for the printer concerned, the input image information is converted to Y, M, C Each exposure device 11 for Y, M, and C prints each color on the photoreceptor 7 based on the image information for each color of Y, M, and C. form a latent image of

Further, in the present embodiment, IR image information is generated from additional information included in the input image information, additional information added by the printer, and the like. The additional information included in the input image information may be information added by an application on the personal computer or information added by a print driver on the personal computer. The IR exposure device 11 forms an IR latent image on the photosensitive member 7 of the IR process unit 6IR based on IR image information.

The latent images of Y, C, M and IR formed on the photoreceptor 7 are supplied with toner from respective developing devices 9 and developed into toner images of Y, C, M and IR. The toner images on the photoreceptors 7 are sequentially superimposed and transferred onto the rotating intermediate transfer belt 12 . Specifically, when the toner image on the photoreceptor 7 reaches the position of the primary transfer nip, a transfer electric field formed by applying a predetermined voltage to the primary transfer roller 13 causes the toner image on the photoreceptor 7 to be transferred to the intermediate transfer belt. 12 in sequence. In this manner, a full-color toner image (visible image) made up of Y, C, and M toners and an IR toner image (invisible image) made up of IR toner are formed on the surface of the intermediate transfer belt 12 . Toner on each photoreceptor 7 that has not been completely transferred to the intermediate transfer belt 12 is removed by the photoreceptor cleaning device 10 .

Further, when the image forming operation is started, the paper feed roller 19 rotates and the paper P is fed from the paper feed cassette 18 . The conveying of the fed paper P is temporarily stopped by the timing roller 20 . After that, the timing roller 20 is started to rotate at a predetermined timing, and the sheet P is conveyed to the secondary transfer nip at the timing when the toner image on the intermediate transfer belt 12 reaches the secondary transfer nip.

When the paper P is conveyed to the secondary transfer nip, a predetermined voltage is applied to the secondary transfer roller 14, and a transfer electric field is formed in the secondary transfer nip. Then, the toner images on the intermediate transfer belt 12 are collectively transferred onto the paper P by the transfer electric field formed in the secondary transfer nip. At this time, toner remaining on the intermediate transfer belt 12 is removed by the belt cleaning device 17 .

After that, the paper P is conveyed to the fixing device 21 , and the toner image is heated and pressed by the fixing roller 22 and the pressure roller 23 to be fixed on the paper P. FIG. Then, the paper P is discharged outside the apparatus by the paper discharge rollers 24 and placed on the paper discharge tray 25 .

The above description is for the image forming operation when forming a full-color image. It is also possible to form an image using three process units.

Next, control during a special image forming operation for forming both a color toner image and a special toner image, which is a feature of the present invention, will be described with reference to the drawings.
In the following description, when color information of input image information is RGB multi-value information and IR image information (additional information) is included in the input image information, an IR image is generated based on the IR image information. will be described. Note that the additional information included in the input image information does not have to be image information. IR image information is generated from the information. Further, even if the input image information does not include additional information, the control unit 30 may generate IR image information according to the user's designation or the like.

FIG. 2 is a block diagram related to main controls in the printer of this embodiment.
The control unit 30 of the present embodiment mainly includes a main control unit 31, a storage unit 32 as storage means, a color conversion/separation processing unit 33, a gamma conversion unit 34, a total toner amount control unit 35, and a floor. It is composed of a tone conversion section 36 .

The main control unit 31 includes a CPU, RAM, ROM, etc., and executes various programs to perform image processing and overall control of the printer.
The storage unit 32 stores various data and programs used in each unit of the control unit 30 .

The color conversion/separation processing unit 33 uses the color conversion/separation table stored in the storage unit 32 to convert the color information (RGB) of the input image information into Y, M, and C colors, which are color information for a printer. Image information for each of Y, M, and C is generated by converting and decomposing into information. If IR image information is included in the input image information, the IR image information is extracted from the input image information and generated.

The gamma conversion unit 34 uses the gamma conversion table stored in the storage unit 32 to convert each image information of Y, M, and C and, if necessary, IR image information is also subjected to γ (gamma) conversion processing.

Under the control of the main control unit 31, the total toner amount regulation unit 35 uses the toner adhesion amount conversion table stored in the storage unit 32 to form both a color toner image and an IR toner image (special toner image). During the special image forming operation, toner amount suppression control is performed to reduce the color toner amount per unit area as compared with the normal image forming operation in which the same color toner image is formed without forming the IR toner image. That is, in the present embodiment, the main control section 31 and the total toner amount regulation section 35 implement control means for performing toner amount suppression control.

Specifically, the total toner amount regulation unit 35 uses the toner adhesion amount conversion table stored in the storage unit 32 to calculate the toner adhesion amount of Y toner, M toner, C toner, and IR toner per unit area. Toner adhesion amount conversion processing (image processing) is performed for each of Y, M, and C image information subjected to gamma correction (gamma conversion) so that the total amount (hereinafter referred to as "total amount of toner") is equal to or less than the fixing upper limit value. . At this time, toner adhesion amount conversion processing (image processing) may also be performed on IR image information.

The gradation conversion unit 36 uses the dither pattern data stored in the storage unit 32 to perform gradation conversion processing for converting each image information of Y, M, C, and IR into a dither pattern corresponding to the halftone density. to run.

FIG. 3 is a flow chart showing the flow of image forming operation in this embodiment.
When the control unit 30 acquires input image information from a reading device (scanner), a personal computer, or the like (S1), first, it determines whether or not to generate IR image information. Here, it is determined whether or not additional information used to generate IR image information is included in the input image information (S2). When it is determined that additional information is included in the input image information (Yes in S2), IR image information is generated based on the additional information (S3). When the IR image information is included in the input image information, the IR image information is generated by extracting the IR image information from the input image information.

Subsequently, using the color conversion/separation table stored in the storage unit 32, the control unit 30 causes the color conversion/separation processing unit 33 to convert the color information (RGB) of the input image information into printer color information. It is converted and decomposed into certain Y, M, and C color information (S4). Then, the gamma conversion unit 34 performs gamma conversion processing on each of the Y, M, and C image information (S5). When the IR image information is generated in the processing step S3, the gamma conversion unit 34 performs gamma conversion processing on the IR image information (S5).

Next, based on the image information of Y, M, C, and IR after the gamma conversion process, the control unit 30 causes the main control unit 31 to convert the total toner amount per unit area into the image based on the image information. It is determined whether or not there is an excess toner portion exceeding the first specified value, which is the upper limit value of the amount of color toner during the image forming operation (image forming operation in which the image is formed without using IR toner) (S6 ). This determination may be made when it is determined that the additional information (IR image information) is included in the input image information in the processing step S2 described above (that is, during the special image forming operation). It does not need to be run when running.

FIGS. 4A to 4D are schematic diagrams showing toner images obtained by overlapping an IR toner image and Y, M, and C color toner images.
As shown in FIG. 4A, the Y, M, and C color toner images can be superimposed on the IR toner image. is not limited to For example, as shown in FIG. 4B, an IR toner image may be superimposed on the Y, M, and C three-color toner image. Further, for example, as shown in FIG. 4(c), it is also possible to overlap the IR toner images so as to sandwich the IR toner images between the respective color toner images of Y, M, and C. As shown in FIG. When the IR toner image and the Y, M, and C toner images are superimposed, the Y, M, and C toners do not need to be placed on the IR toner, as shown in FIG. 4(d). Also, the case where the Y, M, and C toners are located outside the IR toner is also included. Which stacking method to use can be appropriately selected by, for example, changing the arrangement order of the process units 6Y, 6M, 6C, and 6IR. Also, although IR toner is used as an example here, other special color toner such as white toner can also be applied.

The total toner amount per unit area is, for example, the first specified value when the toner adhesion amount per unit area of each color is expressed as a relative value with the target toner adhesion amount for forming a single-color solid image being 100%. is set to 220%, for example. Since this embodiment does not have a process unit that uses black (K) toner, it is necessary to superimpose Y, M, and C toner images to form a black image portion. The total amount of toner is maximized. During the normal image forming operation, in the color conversion/separation process (S4), when converting and separating the color information (RGB) of the input image information into Y, M, and C color information for the printer, For example, the Y toner adhesion amount, the M toner adhesion amount, and the C toner adhesion amount are each 70% so that the total toner amount per unit area is equal to or less than the first specified value (for example, 220%) even in a black image portion. % (in this case, the total toner amount is 210%). However, when the IR image is superimposed on the black image portion, the total toner amount per unit area may exceed the first specified value (for example, 220%) in that portion. Note that not only the black image portion but also the relatively dark image portion may have a toner total amount exceeding the first specified value when the IR image is superimposed.

If the main control section 31 determines that the total toner amount per unit area includes an excess toner portion exceeding the first specified value (No in S6), it executes fixing condition change control (S7). Specifically, the main control is performed such that the fixing ability of the fixing device 21 is increased, or the fixing processing time of the fixing device 21 is increased, or both, compared to the normal image forming operation. Unit 31 outputs a control command to image formation control unit 40 .

Methods of increasing the fixing ability of the fixing device 21 include, for example, methods of increasing the fixing temperature and increasing the fixing nip pressure. Further, as a method of lengthening the fixing processing time by the fixing device 21, for example, there is a method of reducing the transport speed of the paper P passing through the fixing device 21. FIG.

By changing the fixing conditions in this way, even if there is an excess toner portion exceeding the upper limit of the amount of color toner in the normal image forming operation during the special image forming operation in which the IR image is also formed, 1 To fix toner images of Y, M, C, and IR on a paper P without causing fixing failure by only one fixing process, that is, by passing the paper P only once through a fixing device 21.例文帳に追加can be done.

However, if the fixing ability of the fixing device 21 is increased too much or if the fixing processing time of the fixing device 21 is too long, the fixing processing will be excessive for portions other than the excessive toner portion, resulting in unacceptable image quality deterioration. It could be. Moreover, when the total amount of toner exceeds a certain amount, it may not be possible to achieve sufficient fixing simply by changing the fixing conditions.

As described above, in the normal image forming operation, in the color conversion/separation process (S4), the color information (RGB) of the input image information is converted into Y, M, and C color information for the printer. When separating, even a black image portion is processed so that the total amount of toner per unit area is less than or equal to a first specified value (for example, 220%). However, when an IR image is further superimposed on this black image portion, for example, when an IR image having a toner adhesion amount of 100% of the IR toner image is superimposed, the total toner amount per unit area in that portion is the second standard. values (eg 300%) may be exceeded. It should be noted that not only the black image portion but also the relatively dark image portion may have a toner total amount exceeding the second specified value when the IR image is superimposed.

Therefore, in the present embodiment, based on the Y, M, C, and IR image information after the gamma conversion process, the main control unit 31 controls the total amount of toner per unit area to be reduced once in the image based on the image information. It is determined whether or not there is an unfixable portion exceeding a second specified value (for example, 300%), which is the fixable upper limit value in the fixing process (S8). This determination may also be made when it is determined that the additional information (IR image information) is included in the input image information in the processing step S2 described above (that is, during the special image forming operation). It does not need to be run when running.

If the main control unit 31 determines that the total toner amount per unit area includes an unfixable portion exceeding the second specified value (Yes in S8), the main control unit 31 controls the total toner amount control unit 35 to control the total toner amount. A regulation process is executed (S9). In the total toner amount control processing of this embodiment, normal image formation is performed in which the same color toner image is formed without forming an IR toner image during a special image forming operation in which both a color toner image and an IR toner image are formed. Toner adhesion amount conversion processing (image processing) of each image information of Y, M, and C is performed so that the amount of color toner per unit area becomes smaller than that during operation.

In the total toner amount control process, the toner adhesion amount conversion table stored in the storage unit 32 is used to convert each image information of Y, M, and C after gamma correction (gamma conversion) output from the gamma conversion unit 34. to reduce the amount of toner adhering per unit area in each of the Y, M, and C toner images, and each of the Y, M, and C images having no non-fixable portion where the total amount of toner per unit area exceeds the second specified value. Generate information.

By performing such toner total amount control processing, fixing processing can be performed even when fixing processing becomes excessive or sufficient fixing cannot be achieved in one fixing processing only by changing the fixing conditions. is not excessive, and sufficient fixing can be achieved by one fixing process.

The total toner amount control process is not particularly limited as long as the total toner amount of the unfixable portion can be reduced to the second specified value, which is the fixing upper limit value, or less.
Therefore, for example, only for the unfixable portion, the total toner amount is set to be equal to or less than the second specified value, which is the fixing upper limit, and the portion other than the unfixable portion is maintained as it is. It is also possible to execute the process of converting only the unfixable portion) so that the total amount of toner in the unfixable portion is reduced to the second specified value, which is the fixing upper limit value, or less.
Further, for example, as in the example of overall compression shown in FIG. 5, processing is executed to convert the entire image information so that both luminance and saturation are overall compressed, and the total toner amount of unfixable portions is reduced. may be reduced to a second specified value, which is the fixing upper limit, or less.
Further, for example, as in the example of prioritizing saturation shown in FIG. 6, processing for converting the entire image information is executed so that only the luminance is compressed without changing the saturation, and the total toner amount of the non-fixable portion is calculated. may be reduced to a second specified value, which is the fixing upper limit, or less.
Further, for example, as in the example of prioritizing luminance shown in FIG. 7, a process of converting the entire image information is executed so that only the saturation is compressed without changing the luminance, and the total amount of toner in the non-fixable portion is reduced. It may be reduced to the second specified value, which is the fixing upper limit, or less.
Further, for example, as in another example where luminance is emphasized shown in FIG. 8, processing is executed to convert the entire image information so that only the saturation is compressed without changing the luminance, and the toner in the non-fixable portion is processed. The total amount may be reduced to the second specified value, which is the fixing upper limit, or less.

As described above, according to the present embodiment, when it is determined that the additional information (IR image information) is not included in the input image information (No in S2), that is, in the normal image forming operation, the general In the same manner as in the image forming operation of 1, the color information (RGB) of the input image information is converted into Y, M, and C color information, decomposed (S4), and gamma-converted (S5). Tone conversion processing is executed (S10). Thereafter, the Y, M, and C image information output from the gradation conversion section 36 is sent to the image formation control section 40, and the image formation operation is performed under normal fixing conditions (S11).

The image formation control unit 40 controls the Y, M, and C exposure devices 11 based on the Y, M, and C image information to form the Y, M, and C latent images on the respective photoreceptors 7 . Form on top. Then, the image formation control section 40 controls the developing device 9 to develop each latent image with each toner to form a toner image, and controls each section of the transfer section 2 to sequentially superimpose them on the intermediate transfer belt 12 . After the combined transfer, the toner images on the intermediate transfer belt 12 are transferred to the paper P collectively. After that, the image formation control section 40 controls the fixing device 21 to fix the toner image on the paper P and discharge it outside the device.

On the other hand, if it is determined that the additional information (IR image information) is included in the input image information (Yes in S2), that is, during the special image forming operation, fixing condition change control and toner amount suppression control are performed. is executed. Specifically, when the total toner amount per unit area exceeds the first specified value and includes an excessive toner portion equal to or less than the second specified value (No in S6, No in S8), toner amount suppression control is performed. is not executed, but fixing condition change control is executed (S7) to suppress the occurrence of defective fixing even in one fixing process.

On the other hand, in the case of the special image forming operation, if the total amount of toner per unit area exceeds the first specified value and includes an unfixable portion that also exceeds the second specified value (No in S6, Yes in S8). In addition to the fixing condition change control (S7), the toner total amount regulation process is also executed (S9), and even if the situation cannot be dealt with only by changing the fixing condition, the occurrence of fixing failure is suppressed in one fixing process.

According to the present embodiment, as described above, when an IR image is further superimposed on a black image portion, the total toner amount per unit area exceeds the second specified value (for example, 300%) at that portion, and the total toner amount regulation Processing is performed. Therefore, in the printer of the present embodiment, the black image formed by superimposing the IR toner image on the Y, M, and C color toner images is higher than the image density of the black image formed only by the Y, M, and C color toner images. , the image density of is lower.

In the present embodiment, during the special image forming operation, only fixing condition change control is executed according to the total toner amount, or both fixing condition change control and total toner amount regulation processing as toner amount suppression control are executed. Run. However, it is also possible to execute only the total toner amount regulation process without executing the fixing condition change control.

Further, in this embodiment, the color conversion separation table stored in the storage unit 32 is used as the color conversion data for converting the color information of the input image information into the color information for the printer during the normal image forming operation. The color conversion separation table and the toner adhesion amount conversion table stored in the storage unit 32 are used as special color conversion data when performing toner total amount control processing as toner amount control control using normal color conversion data.

Further, in the present embodiment, it is determined whether or not to execute total toner amount regulation processing as fixing condition change control or toner amount suppression control depending on whether or not the total toner amount exceeds the first prescribed value or the second prescribed value. However, the conditions for whether or not to execute the fixing condition change control and the total toner amount regulation process are not limited to these. For example, when it is determined that additional information (IR image information) is included in the input image information, processing can be simplified by always executing fixing condition change control or toner total amount regulation processing. I can plan.

In the image forming apparatus according to the present embodiment, when printing a so-called one-dimensional code (barcode) using IR toner, it is printed at a normal granularity (106 lines/inch). This is because the reading accuracy of the one-dimensional code is higher when the granularity is lower. A solid image is basically used. As for actual behavior, in the mode for printing one-dimensional codes, a solid image is created at 106 lines/inch, and in the mode (IR mode) for printing figures (characters, symbols, etc.) other than one-dimensional codes, 30 lines/inch An image is created with a screen ruling of , and an image area ratio of 5%.

Note that the image area ratio and granularity can be changed even in the IR mode. By doing so, it is possible to adjust or switch the visibility difficulty level and the granularity level as necessary. For example, in a case where it is desired to improve the degree of visual recognition difficulty even if the granularity is somewhat poor, it is preferable that the operator or the like can adjust or switch to lower the image area ratio and increase the granularity.

In addition, since the visibility changes depending on the superposition of colors, for example, when executing the IR mode with a single color of IR toner, an IR toner image is formed with a screen ruling of 30 lines/inch and an image area ratio of 5%. When two colors are superimposed, an IR toner image is formed with a screen ruling of 10 lines/inch and an image area ratio of 5%. That is, there are an IR toner single color mode and a color superimposition mode. When colors are superimposed, the degree of visibility increases. Therefore, when there are many colors to be superimposed, the image area ratio of the IR image is maintained or lowered compared to when there are few colors to be superimposed, and the degree of granularity is controlled to be high. will be

Further, in the image forming apparatus of the present embodiment, when printing a normal color toner image, it is set so that printing is performed with a preset screen ruling (default set value), and IR toner is used. When it is used, the screen ruling is reduced (by changing the granularity, spatial frequency, and the number of isolated dots) and printing is performed. More specifically, at least when only color toner is printed (color toner mode, first mode), a predetermined number of screen lines is used, and when IR toner is used, visibility is reduced (visible Impossible mode, second mode), a mode in which the number of screen lines is reduced is available.

In the mode for lowering the visibility, the image area ratio is at least lower than that of the solid image. Both the image area ratio and the number of screen lines in the mode when the visibility is lowered are set to preset values as default values, but both or either one can be changed by the operator. But it's okay. In this case, it is desirable that the default image area ratio is set to 50% or less and the screen ruling is set to 40 lines/inch or less in the visibility-lowering mode. The image area ratio is naturally set to be smaller than solid.

Also, here, an example in which an IR toner image and three-color toner images of Y, M, and C are superimposed has been described, but the present invention is not limited to this. Color toner image, two-color toner image of C toner image and Y toner image on IR toner image, two-color toner image of Y toner image and M toner image on IR toner image, or Y, M, C It is applicable even when a toner image of any one color and an IR toner image are superimposed. Note that the example shown in FIG. 9A is an example in which two color toner images of Y and M are superimposed on the IR toner image, and the example shown in FIG. This is an example in which only M toner images are superimposed.

Next, the toner used in this embodiment will be described.
The toner set of this embodiment is a toner set including color toners and IR toners that are special toners.
A color toner contains a binder resin, a colorant, and, if necessary, other components.
The IR toner contains a binder resin, a near-infrared light absorbing material, and, if necessary, other components.

In this embodiment, when the toner set satisfies any one of the following conditions, the image quality of the color toner image is determined when the color toner image formed on the surface of the recording medium together with the IR toner image (invisible toner image) is visually observed. is preferable in terms of providing a toner set with good visibility and reading accuracy of the IR toner image.
The first condition is that there are color toners and IR toners, the IR toner solid image has a 60-degree gloss of 30 or more, and the IR toner solid image has a 60-degree gloss that is higher than that of the color toner. 10 or more higher than the 60 degree glossiness of the solid image.
The second condition is that there are color toners and IR toners, the tangent loss (tan δi) of the IR toners in the range of 100° C. or more and 140° C. or less is 2.5 or more, and the color toners are 100° C. The tangent loss (tan δc) within the range of 140° C. or higher is 2 or less.

In the toner described in Japanese Patent Application Laid-Open No. 2001-265181, since there is no regulation for superimposed toner images, there is a problem that an invisible image becomes visible due to the difference in glossiness of the superimposed images. In order to solve the problem, JP-A-2007-171508, JP-A-2007-003944, and JP-A-2010-113368 propose an IR toner having a glossiness lower than that of the color toner used. are proposing to However, in recent years, there has been an increasing demand for a relatively low-gloss image for electrophotographic image output, rather than for differentiation from high-gloss images such as in general offset printing. Therefore, when the color toner has a high glossiness, not only the secondary and tertiary colors, but also the high-adhesion portion such as the overlapping portion with the invisible image (IR image) becomes highly glossy, and the position of the IR image becomes conspicuous to the naked eye. A problem arises. Furthermore, when a color toner image is formed on an IR image, the color toner layered on the IR toner layer is likely to enter when the fixing nip is heated and pressurized. There is a problem of stability.

<IR Toner>
The IR toner contains a binder resin, a near-infrared light absorbing material, and, if necessary, other components.

<<Binder Resin>>
The binder resin is not particularly limited, and all conventionally known resins can be used. Examples of binder resins include styrene, α-methylstyrene, chlorostyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene- Styrenic resins such as maleic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-acrylonitrile-acrylic acid ester copolymer, polyester resin, vinyl chloride resin, rosin-modified malein acid resins, phenol resins, epoxy resins, polyethylene resins, polypropylene resins, ionomer resins, polyurethane resins, silicone resins, ketone resins, xylene resins, petroleum resins, hydrogenated petroleum resins, and the like. These may be used individually by 1 type, and may use 2 or more types together. Among these, styrenic resins and polyester resins containing aromatic compounds as constitutional units are preferred, and polyester resins are more preferred.

A polyester resin is obtained by a generally known polycondensation reaction between an alcohol and an acid.
Examples of alcohols include diols such as polyethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-propylene glycol, neopentyl glycol, and 1,4-butenediol. , 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylene bisphenol A and other etherified bisphenols, saturated or Dihydric alcohol units substituted with unsaturated hydrocarbon groups, other dihydric alcohol units, sorbitol, 1,2,3,6-hexanetetrol, 1,4-salbitan, pentaerythritol di Pentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butane triol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, and other high alcohol monomers having a valence of 3 or higher; These may be used individually by 1 type, and may use 2 or more types together.

The acid is not particularly limited and can be appropriately selected depending on the purpose, but carboxylic acid is preferred.
Carboxylic acids include, for example, monocarboxylic acids such as palmitic acid, stearic acid and oleic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malon acids, divalent organic acid monomers substituted with saturated or unsaturated hydrocarbon groups having 3 to 22 carbon atoms, anhydrides of these acids, dimers of lower alkyl esters and linoleic acid, 1, 2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1, 2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid embol trimer acid, Trivalent or higher polyvalent carboxylic acid monomers such as anhydrides of these acids are included. These may be used individually by 1 type, and may use 2 or more types together.

The binder resin can also contain a crystalline resin.
The crystalline resin is not particularly limited as long as it has crystallinity and can be appropriately selected according to the purpose. Examples include polyester resins, polyurethane resins, polyurea resins, polyamide resins, polyether resins, vinyl Examples include resins and modified crystalline resins. These may be used individually by 1 type, and may use 2 or more types together. Among these, polyester resins, polyurethane resins, polyurea resins, polyamide resins, and polyether resins are preferable. is preferred.

The weight average molecular weight (Mw) of the crystalline resin is preferably from 2,000 to 100,000, more preferably from 5,000 to 60,000, and particularly from 8,000 to 30,000, from the viewpoint of fixability. preferable. When the weight average molecular weight is 2,000 or more, it is possible to prevent the problem of deterioration of hot offset resistance, and when it is 100,000 or less, it is possible to prevent the problem of deterioration of low temperature fixability.

<<Near-infrared light absorption material>>
As the near-infrared light absorbing material, both inorganic materials and organic materials can be used.
So far, various transparent (invisible) infrared absorbing materials have been investigated for the additional data embedding technique, and various materials have been disclosed. For example, in inorganic materials, rare earth metals such as ytterbium (JP-A-9-77507, JP-A-9-104857) and infrared absorbing materials containing copper phosphate crystallized glass (JP-A-7-53945) , Japanese Patent Laid-Open No. 2003-186238), etc. Examples of organic materials include aluminum compounds (Japanese Patent Laid-Open No. 7-271081) and croconium dyes (Japanese Patent Laid-Open No. 2001-294785). Further, Japanese Patent Laid-Open No. 2002-146254 discloses an organic material containing an infrared absorbing material having a spectral absorption maximum wavelength of 750 nm to 1100 nm and having an absorbance at 650 nm of 5% or less of the absorbance at the spectral absorption maximum wavelength. material is proposed. Furthermore, in JP-A-2007-171508, JP-A-2007-3944, JP-A-2010-113368, and JP-A-2008-76663, it is proposed to use a naphthalocyanine pigment, and visible It can be said that this is an excellent technique from the standpoint of the difference in absorbance of light and absorbance in the infrared region.

Examples of inorganic near-infrared light absorbing materials include known glass network-forming components that transmit visible wavelengths, such as phosphoric acid, silica, boric acid, transition metal ions, and inorganic and/or organic compounds. Examples include glass to which a material such as a dye is added, and crystallized glass obtained by crystallizing this by heat treatment. These inorganic materials reflect light in the visible region well, and an invisible image can be obtained.

Examples of organic near-infrared light absorbing materials include colored materials such as phthalocyanine compounds and anthraquinone compounds; colorless materials such as aluminum salt compounds and naphthalocyanine compounds. Among these, the colorless material is preferable because it does not color the image when added, and since the absorption in the infrared region is sufficiently large, the amount of addition can be suppressed, and as a result, the image quality of the color image is not impaired. .
Among colorless materials, naphthalocyanine-based compounds are preferred because they have very low absorbance in the visible light region, are nearly colorless, and have little effect on toner charging.

The naphthalocyanine-based compound is not particularly limited and can be appropriately selected depending on the intended purpose, but the compounds exemplified below are preferred.

However, in chemical formula (1), Met represents two hydrogen atoms, a divalent metal atom, or a trivalent or tetravalent substituted metal atom, and A ¹ to A ⁸ may be the same or different, respectively, hydrogen atom, halogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aryloxy group, substituted or unsubstituted alkylthio group or substituted or represents an unsubstituted arylthio group, provided that in each combination of A ¹ and A ² , A ³ and A ⁴ , A ⁵ and A ⁶ , A ⁷ and A ⁸ , both of which are hydrogen atoms or halogen atoms at the same time Y ¹ to Y ¹⁶ may be the same or different and are each a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group , substituted or unsubstituted aryloxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted arylthio group, substituted or unsubstituted alkylamino group, substituted or unsubstituted dialkylamino group, substituted or unsubstituted aryl amino group, substituted or unsubstituted diarylamino group, substituted or unsubstituted alkylarylamino group, hydroxy group, mercapto group, nitro group, nitrile group, oxycarbonyl group, alkoxycarbonyl group, aryloxycarbonyl group, aminocarbonyl group or represents a mono- or di-substituted aminocarbonyl group.

The reflectance of the reading wavelength of the near-infrared light absorbing material is preferably 50% or less from the viewpoint of stable mechanical reading by infrared light irradiation. If the reflectance is 50% or less, it is possible to prevent the problem of lower reading accuracy.
As a method for measuring reflectance, for example, an output solid image can be measured using a spectrophotometer (eg, V-660 (manufactured by JASCO Corporation), eXact (manufactured by X-Rite), etc.). can.

The near-infrared light absorbing material is preferably dispersed in the toner particles.
When the near-infrared light absorbing material is externally fixed to the toner surface or mixed and added to the toner particles, there is a possibility that material aggregation may occur in the toner particles and developer. In the stage of external fixation on the surface or developer adjustment, it is lost due to adhesion to equipment, etc., and the near-infrared light absorbing material in the IR image is insufficient or unevenly distributed, making it impossible to read information accurately and stably. . In addition, the released near-infrared light-absorbing material may contaminate the inside of the machine, especially the photoreceptor, etc., which may adversely affect other processes such as development and transfer. In addition, when the above-mentioned organic near-infrared light absorbing material is used, it has better dispersibility in the binder resin than the inorganic material, and is uniformly dispersed in the IR image formed on the image output medium. It exhibits sufficient absorption in the infrared region without impairing its invisibility, allowing information to be recorded at high density, and because it has good dispersibility in the toner, machine reading and decoding of IR images can be performed for a long period of time. It is possible to stably perform

The numerical range of the content of the near-infrared light absorbing material varies depending on the properties of the near-infrared light absorbing material. Regardless of the type of content of the near-infrared light-absorbing material, if the content is insufficient, the absorption of near-infrared light will be insufficient. Insufficient absorption of near-infrared light requires more IR toner to adhere to media such as paper. As a result, visible irregularities are caused by aggregates (aggregates) of the IR toner, and resources are wasted. If the content of the near-infrared light-absorbing material is excessive, the near-infrared light-absorbing material has absorption in the visible light wavelength range, albeit slightly. For this reason, there arises a problem that the near-infrared light absorbing material itself becomes easily visible.
In the case of vanadyl naphthalocyanine, which is often used as a transparent (invisible) near-infrared light absorbing material, the content is 0.3% by mass or more and 1.0% by mass or less relative to the IR toner. preferable.

<<Other Ingredients>>
Other components are not particularly limited as long as they are usually contained in the toner, and can be appropriately selected according to the intended purpose. be done.

<<<Mold Release Agent>>>
As the release agent, both natural wax and synthetic wax can be used. These may be used individually by 1 type, and may use 2 or more types together.
Examples of natural waxes include plant waxes such as carnauba wax, cotton wax, wood wax and rice wax; animal waxes such as beeswax and lanolin; mineral waxes such as ozokerite and cercin; and petroleum wax.

Synthetic waxes include synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax; synthetic waxes such as esters, ketones and ethers; 1,2-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, chlorine fatty acid amides such as hydrocarbons; homopolymers or copolymers of polyacrylates such as polyn-stearyl methacrylate and polyn-lauryl methacrylate, which are low-molecular-weight crystalline polymers (e.g., n-stearyl methacrylic acrylate, crystalline polymers having long-chain alkyl groups in side chains such as ethyl acid copolymers).

Among these, the release agent preferably contains monoester wax. Since monoester waxes have low compatibility with general binder resins, they tend to seep out to the surface during fixation, show high releasability, and can ensure high glossiness and high low-temperature fixability.
The monoester wax is preferably a synthetic ester wax. Synthetic ester waxes include, for example, monoester waxes synthesized from long-chain straight saturated fatty acids and long-chain straight saturated alcohols. The long-chain straight saturated fatty acid is represented by the general formula C _n H _2n+1 COOH, and those with n=5 to 28 are preferably used. Further, the long-chain linear saturated alcohol is represented by C _n H _2n+1 OH, where n is preferably about 5 to 28.

Specific examples of long-chain straight saturated fatty acids include capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecanoic acid, tetradecanoic acid, stearic acid, nonadecanic acid, aramonic acid, behenic acid, lignoceric acid, cerotic acid, heptacosanoic acid, montanic acid and melissic acid. On the other hand, specific examples of long-chain linear saturated alcohols include amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, capryl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, Examples include myristyl alcohol, pentadecyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, nonadecyl alcohol, eicosyl alcohol, ceryl alcohol and heptadecanenool, and substituents such as lower alkyl groups, amino groups, and halogens. may have.

The melting point of the release agent is preferably 50°C to 120°C. If the release agent has a melting point within the numerical range, it can effectively act as a release agent between the fixing roller and the toner interface. Offset resistance can be improved. Specifically, when the melting point is 50° C. or higher, it is possible to prevent the deterioration of the heat-resistant storage stability of the toner. It is possible to prevent problems such as deterioration of offset property and paper winding around the fixing device.
The melting point of the release agent can be determined by measuring the maximum endothermic peak using a differential scanning calorimeter TG-DSC system TAS-100 (manufactured by Rigaku Denki Co., Ltd.).

The content of the release agent is preferably 1% by mass to 20% by mass, more preferably 3% by mass to 10% by mass, relative to the binder resin. If the content is 1% by mass or more, the problem of insufficient anti-offset effect can be prevented, and if the content is 20% by mass or less, the problem of reduced transferability and durability can be prevented. can be done.

The content of the monoester wax is preferably 4 to 8 parts by mass, more preferably 5 to 7 parts by mass, per 100 parts by mass of the IR toner. When the content is 4 parts by mass or more, the bleeding to the surface during fixing becomes insufficient, the releasability deteriorates, and the gloss, low-temperature fixability, and high-temperature offset resistance deteriorate. It is possible to prevent such troubles. When the content is 8 parts by mass or less, the amount of release agent deposited on the surface of the toner increases, the storage stability of the toner decreases, and filming on a photoreceptor decreases. be able to.

The toner of the present embodiment preferably contains a wax dispersant, and the dispersant is a copolymer composition containing at least styrene, butyl acrylate, and acrylonitrile as monomers, and a polyethylene adduct of the copolymer composition. is preferred.
The content of the wax dispersant is preferably 7 parts by mass or less with respect to 100 parts by mass of the IR toner. By containing a wax dispersant, a wax dispersing effect can be obtained, and a stable improvement in storage stability can be expected regardless of the production method. Further, the wax diameter is reduced by the effect of dispersing the wax, so that the filming phenomenon on the photosensitive member or the like can be suppressed. If the content is 7 parts by mass or less, the amount of components incompatible with the polyester resin increases, the gloss is lowered, and the dispersibility of the wax becomes too high, so the filming resistance is improved, but during fixing, It is possible to prevent problems such as deterioration of low-temperature fixability and hot offset resistance due to poor exudation of wax to the surface.

<<<Charge Control Agent>>>
As the charge control agent, all known ones can be used. Examples include primary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus elements or compounds, fluorine-based activators, salicylic acid metal salts, and salicylic acid derivative metal salts. These may be used individually by 1 type, and may use 2 or more types together.

As the charge control agent, an appropriately synthesized one may be used, or a commercially available product may be used. Commercially available products include, for example, Bontron 03, Bontron P-51, Bontron S-34, E-82, E-84, E-89 (manufactured by Orient Chemical Industry Co., Ltd.), TP-302, TP-415, Copy. Charge PSY VP2038, Copy Blue PR, Copy Charge NEG VP2036, Copy Charge NX VP434 (manufactured by Hoechst Co., Ltd.), LRA-901, LR-147 (manufactured by Nippon Carlit Co., Ltd.) and the like.

The content of the charge control agent can be appropriately selected according to the type of binder resin, the presence or absence of additives used as necessary, and the toner manufacturing method including the dispersion method. It is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 2 parts by mass. If the content is 5 parts by mass or less, the chargeability of the toner is too high, the effect of the main charge control agent is reduced, the electrostatic attraction force with the developing roller is increased, and the fluidity of the developer is reduced. , it is possible to prevent the problem of lowering the image density.

Further, it is possible to control the thermophysical properties of the toner by using a trivalent or higher metal salt among charge control agents. By containing the metal salt, a cross-linking reaction proceeds with the acidic groups of the binder resin during fixation, forming weak three-dimensional cross-links, thereby maintaining low-temperature fixability and obtaining high-temperature anti-offset properties. can.

Examples of metal salts include metal salts of salicylic acid derivatives, metal salts of acetylacetonate, and the like. The metal is not particularly limited as long as it is a polyvalent ion metal having a valence of 3 or higher, and can be appropriately selected according to the purpose. Examples thereof include iron, zirconium, aluminum, titanium, and nickel. Among these, trivalent or higher salicylic acid metal compounds are preferable.

The content of the metal salt is not particularly limited and can be appropriately selected according to the intended purpose. 5 parts by mass to 1 part by mass is more preferable. When the content is 0.5 parts by mass or more, the problem of poor hot offset resistance can be prevented, and when the content is 2 parts by mass or less, the problem of poor glossiness can be prevented. can.

<<<external additives>>>
External additives are contained to assist fluidity, developability, and chargeability. The external additive is not particularly limited and can be appropriately selected depending on the intended purpose. Examples thereof include inorganic fine particles and polymeric fine particles.
Examples of inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, Chromium oxide, cerium oxide, pengal oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride and the like. These may be used individually by 1 type, and may use 2 or more types together.
Examples of polymer-based fine particles include polystyrene obtained by soap-free emulsion polymerization, suspension polymerization, and dispersion polymerization, polycondensation of methacrylic acid ester, acrylic acid ester copolymer, silicone, benzoguanamine, nylon, etc., thermosetting Examples include polymer particles made of resin.

The external additive can be surface-treated with a surface-treating agent to increase hydrophobicity and prevent deterioration of flow characteristics and charging characteristics even under high humidity.
Examples of surface treatment agents include silane coupling agents, silylating agents, silane coupling agents having alkyl fluoride groups, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils, and the like. mentioned.

The primary particle size of the external additive is preferably 5 nm to 2 μm, more preferably 5 nm to 500 nm. Moreover, the specific surface area of the external additive by the BET method is preferably 20 m ² /g to 500 m ² /g.
The content of the external additive is preferably 0.01% by mass to 5% by mass, more preferably 0.01% by mass to 2.0% by mass, relative to the IR toner.

<<<cleanability improver>>>
The cleanability improver is contained in order to remove the post-transfer developer remaining on the photoreceptor or primary transfer medium. Examples of the cleaning improver include fatty acid metal salts such as zinc stearate, calcium stearate and stearic acid; polymer fine particles such as polymethyl methacrylate fine particles and polystyrene fine particles produced by soap-free emulsion polymerization. The fine polymer particles have a relatively narrow particle size distribution and preferably have a volume average particle size of 0.01 to 1 μm.

<Color Toner>
A color toner contains a binder resin, a colorant, and, if necessary, other components. As for other components, the same ones as those for other components can be used.
The color toner is preferably cyan toner, magenta toner, or yellow toner, and more preferably cyan toner, magenta toner, or yellow toner. In other words, in the toner set, the 60-degree glossiness of the IR toner solid image is preferably 10 or more higher than the 60-degree glossiness of the cyan toner, magenta toner, or yellow toner solid image. More preferably, it is 10 or more higher than the 60-degree glossiness of all solid images of magenta toner and yellow toner.

<<Binder Resin>>
It is preferable that the toner image formed with the color toner of the present embodiment has a low gloss as compared with general offset printing.
Therefore, the binder resin contained in the color toner is not particularly limited and can be appropriately selected depending on the intended purpose, but it preferably contains a gel. The gel fraction is preferably 0.5% by mass or more and 20% by mass or less, more preferably 1.0% by mass or more and 10% by mass or less, relative to the binder resin.
Even if gel is not included, the binder resin used in color toners preferably contains a high molecular weight substance having a weight average molecular weight Mwc of 100,000 or more. More preferably, it is greater than Mwi. By making the weight-average molecular weight Mwc of the binder resin used in the color toner larger than the weight-average molecular weight Mwi of the binder resin used in the IR toner, 60-degree glossiness with high visibility compared to offset printing , a color image gloss of about 10 to 30 can be obtained.

<<coloring agent>>
As the coloring agent, those having low absorption at wavelengths of 800 nm or more are preferable. Azo Yellow, Oil Yellow, Hansa Yellow (GR, A, RN, R), Pigment Yellow L, Benzidine Yellow (G, GR), Permanent Yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazane Yellow BGL, Isoindolinone Yellow, Bengara, Red Lead, Red Lead, Cadmium Red, Cadmium Mercury Red, Antimony Vermillion, Permanent Red 4R, Para Red, Phise Red, Para Chloro-Nitroaniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fastlubin B, Brilliant Scarlet G, Risol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pogment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermillion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkali Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal-Free Phthalocyanine blue, phthalocyanine blue, fast sky blue, indanthrene blue (RS, BC), indigo, dioxane violet, anthraquinone violet, chrome green, zinc green, pyridian, emerald green, pigment green B, naphthol green B, green gold, acid green lake, malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc white, litobone, perylene black, perinone black and mixtures thereof; These may be used individually by 1 type, and may use 2 or more types together.

When used as process color toners, the following colorants are preferred for each of cyan, magenta, and yellow.
In cyan, C.I. I. Pigment Blue 15:3 is preferred. In magenta, C.I. I. Pigment Red 122, C.I. I. Pigment Red 269, and C.I. I. Pigment Red 81:4 is preferred. In Yellow, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 155, C.I. I. Pigment Yellow 180, and C.I. I. Pigment Yellow 185 is preferred. These coloring agents may be used singly or in combination of two or more.

The absorbance of the colorant at 800 nm or more is preferably less than 0.05, more preferably less than 0.01. When the absorbance is less than 0.05, it is possible to prevent the problem that when the color toner is superimposed on the IR toner, reading of information formed by the IR toner is hindered.

The content of the colorant is preferably 3% by mass to 12% by mass, more preferably 5% by mass to 10% by mass, with respect to the entire color toner of each color, depending on the coloring power of each colorant. When the content is 3% by mass or more, it is possible to prevent the problem that the coloring power is not sufficient and the monochromatic toner adhesion amount increases, resulting in waste of resources. When the content is 12% by mass or less, it is possible to prevent the problem that the chargeability of the toner is greatly affected and it becomes difficult to maintain a stable toner charge amount.

<Characteristics of IR Toner and Color Toner>
The 60 degree glossiness of the IR toner solid image is 30 or more, preferably 30 or more and 80 or less, and more preferably 30 or more and 60 or less. If the 60-degree glossiness of the solid image is less than 30, the visibility of the IR toner image is increased, and the intended hidden image does not function. If it is more than 80, the molecular weight of the toner resin becomes small, and it may become difficult to maintain a sufficient fixing temperature range.
The 60-degree glossiness of the solid image of the color toner is preferably 10 or more and 40 or less, more preferably 15 or more and 35 or less. When the glossiness is within the numerical range, the color toner image has relatively low glossiness.
The 60-degree glossiness of the IR toner solid image is 10 or more, preferably 15 or more, and more preferably 20 or more higher than the 60-degree glossiness of the color toner solid image. When the difference between the 60-degree glossiness of the IR toner solid image and the 60-degree glossiness of the color toner solid image is less than 10, the IR toner image is formed on the image output medium before heat fixing during image formation. When a color toner image is superimposed on the , the color toner in the upper layer penetrates into the IR toner layer in the lower layer during fixing by heating and pressurization, and the visibility of the color toner image deteriorates. That is, since the glossiness of the solid image of the IR toner is higher than that of the solid image of the color toner, the visibility of the color toner image superimposed on the upper layer is improved. The image becomes difficult to see.

The absorbance of the solid image of the color toner at 800 nm or more is preferably less than 0.05, more preferably less than 0.01.

Means for adjusting the glossiness of solid images of IR toner and color toner include, for example, adjusting the gel ratio of the binder resin and adjusting the weight average molecular weight of the binder resin. The higher the gel fraction of the binder resin, the lower the gloss, and the closer the gel fraction to 0, the higher the gloss. When a binder resin containing no gel is used, gloss tends to be lower as the weight average molecular weight of the binder resin increases, and gloss tends to be higher as the weight average molecular weight is lower.
Furthermore, when a resin having an acid value is used as the binder resin, it is possible to adjust the gloss by adding a trivalent or higher metal salt. The higher the binder resin acid value and the larger the amount of metal salt added, the lower the gloss tends to be, and the lower the binder resin acid value and the smaller the amount of metal salt added, the higher the gloss tends to be.

The weight average molecular weight (Mwi) of the IR toner is preferably 6,000 to 12,000, more preferably 7,500 to 10,000.
As the weight-average molecular weight, the molecular weight distribution of the THF-soluble portion can be measured with a GPC (gel permeation chromatography) measuring device GPC-150C (manufactured by Waters Co.).
Measurement of the weight-average molecular weight is carried out, for example, using a column (KF801-807: manufactured by Shodex Co., Ltd.) in the following manner.
The column is stabilized in a heat chamber at 40° C., and THF as a solvent is passed through the column at this temperature at a flow rate of 1 ml per minute. Then, after sufficiently dissolving 0.05 g of the sample in 5 g of THF, it was filtered through a pretreatment filter (for example, pore size 0.45 μm Chromatodisk (manufactured by Kurabo Industries)), and finally the sample concentration was 0.05% by mass to 0.05% by mass. 50 μL to 200 μL of a THF sample solution of a resin adjusted to 6% by mass is injected for measurement.

The IR toner preferably has a gel fraction of 0% by mass to 2% by mass.
The gel fraction can be calculated from the dry weight of the component filtered through the pretreatment filter used in measuring the weight average molecular weight.

The ratio of weight average molecular weight (Mw)/number average molecular weight (Mn) of the IR toner is preferably 5 or less, more preferably 4 or less.
As a method for measuring the weight average molecular weight Mw and the number average molecular weight Mn, the molecular weight distribution of the IR toner is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count number.
As standard ^{polystyrene samples} for ^preparing a ^{calibration curve} , for example, the 10 ⁵ , 3.9×10 ⁵ , 8.6×10 ⁵ , 2×10 ⁶ , 4.48×10 ⁶ (manufactured by Pressure Chemical Co. or Toyo Soda Kogyo Co., Ltd.) and the like. It is appropriate to use at least 10 standard polystyrene samples to prepare the calibration curve. An RI (refractive index) detector is used as the detector.

The acid value of the IR toner is preferably 12 mgKOH/g or less, more preferably 6 mgKOH/g to 12 mgKOH/g. The acid value can be set within a numerical range by using a polyester resin as the binder resin, and it is easy to achieve both low-temperature fixability and hot offset resistance.
The acid values of the toner and the binder resin in this embodiment were measured under the following conditions according to the measuring method described in JIS K0070-1992.
To prepare the sample solution, 0.5 g of toner or binder resin (0.3 g of ethyl acetate soluble component) was added to 120 mL of toluene and dissolved by stirring at room temperature (23° C.) for about 10 hours. Furthermore, 30 mL of ethanol was added to prepare a sample solution.
The measurement can be calculated by the device, but specifically calculated as follows. Titration was performed with a pre-standardized N/10 caustic potash-alcohol solution, and the acid value was obtained from the consumption of the alcohol potash solution by the following calculation.
Acid value = KOH (number of mL) x N x 56.1/sample mass (where N is the factor of N/10 KOH)
In Examples and Comparative Examples described below, the acid values of the binder resin and the toner were substantially the same. Therefore, the acid value of the binder resin is treated as the acid value of the toner.

<<Toner Particle Diameter>>
The weight average particle diameter of the IR toner is preferably 5 μm or more and 7 μm or less, more preferably 5 μm or more and 6 μm or less.
The weight average particle size of the color toner is preferably 4 μm or more and 8 μm or less, more preferably 5 μm or more and 7 μm or less.
When the weight-average particle size is within the range, fine dots of 600 dpi or more can be reproduced, and high-quality images can be obtained. This has the advantage of being able to have sufficiently small toner particles for minute latent image dots and excellent dot reproducibility.
In particular, IR toner is arranged at a high density before it is transferred and fixed on the image output medium, and by preventing the color toner superimposed on it from entering the gap, fixing with high reproducibility is achieved. Later images can be obtained. The highly reproducible image can be machine-read by irradiating infrared light, enabling more stable processing.
When the weight average particle diameter (D4) of the color toner is 4 μm or more, phenomena such as a decrease in transfer efficiency and blade cleaning performance can be prevented. If there is, as described above, it is possible to suppress the inconvenience that image information tends to be disturbed due to the overlapping color toner entering the image before fixing, and it is difficult to suppress scattering of characters and lines. .

The ratio (D4/D1) of the weight average particle diameter (D4) to the number average particle diameter (D1) is preferably 1.00 to 1.40, more preferably 1.05 to 1.30. The closer the ratio (D4/D1) to 1.00, the sharper the particle size distribution.
Such a toner with a small particle size and a narrow particle size distribution has a uniform charge amount distribution and can produce high-quality images with little background fogging. can do.
In a full-color image forming method in which a multi-color image is formed by superimposing toner images of different colors, the image is formed using only black toner, and thus the image forming method does not need to superimpose toner images of different colors. The amount of toner deposited on the paper is large.
In other words, since the amount of toner to be developed, transferred, and fixed increases, problems that deteriorate image quality such as the above-mentioned decrease in transfer efficiency, decrease in blade cleaning performance, scattering of characters and lines, background fogging, etc. It is important to manage the diameter (D4) and the ratio (D4/D1) of the weight average particle diameter (D4) and the number average particle diameter (D1).

The particle size distribution of the toner particles can be measured using a particle size distribution measuring apparatus for toner particles by the Coulter counter method. Examples of the apparatus include Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter).
A specific measuring method is as follows.
First, 0.1 mL to 5 mL of a surfactant (such as alkylbenzenesulfonate) is added as a dispersant to 100 mL to 150 mL of the electrolytic aqueous solution. The electrolytic aqueous solution is an approximately 1% NaCl aqueous solution prepared using primary sodium chloride, and examples thereof include ISOTON-II (manufactured by Coulter).
Next, 2 mg to 20 mg of the measurement sample is added. The electrolytic solution in which the sample is suspended is subjected to dispersion treatment in an ultrasonic disperser for about 1 to 3 minutes, and the weight and number of toner particles or toner are measured by a measuring device using a 100 μm aperture as an aperture. Calculate weight distribution and number distribution. From the obtained distribution, the weight average particle diameter (D4) and number average particle diameter (D1) of the toner can be obtained.
2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; 8.00 to less than 10.08 μm; 10.08 to less than 12.70 μm; 12.70 to less than 16.00 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm, using 13 channels, targeting particles with a size greater than or equal to 2.00 μm and less than 40.30 μm.

It is known that the tangent loss (tan δ) of toner for electrophotographic development has a clear correlation with the glossiness of the image. As the value of tan δ increases, the spreadability of the toner during fixing increases, the substrate hiding property increases, and a highly glossy image can be obtained.
The tangent loss (tan δi) of the IR toner at 100° C. to 140° C. is preferably 2.5 or more, more preferably 3.0 or more. tan δi is preferably 15 or less. The tangent loss (tan δi) of the IR toner at 100° C. to 140° C. of 2.5 or more means that the tangent loss (tan δi) of the IR toner is always 2.5 or more at 100° C. to 140° C. means to take
The tangent loss (tan δc) of the color toner is preferably 2 or less. tan δc is preferably 0.1 or more. When the tangent loss of the color toner is 2 or less, it is possible to prevent the problem that the color toner superimposed on the IR image enters the IR toner image and impairs the stability of the IR toner image. The tangent loss (tan δc) of the color toner at 100°C to 140°C of 2 or less means that the tangent loss (tan δc) of the color toner always takes a value of 2 or less at 100°C to 140°C. do.

The tangent loss (tan δ) of a toner for electrophotographic development is the ratio (G'')/(G') of the loss modulus (G'') and the storage modulus (G') and is measured by viscoelasticity measurements. be able to. Loss modulus (G'') and storage modulus (G') can be measured, for example, by the following methods. 0.8 g of IR toner or color toner was molded at a pressure of 30 MPa using a die of 20 mm in diameter, and subjected to heating at a frequency of 1.0 Hz using a parallel cone of 20 mm in ADVANCED RHEOMETRIC EXPANSION SYSTEM (manufactured by TA). 2.0 ° C./min, strain 0.1% (automatic strain control: minimum allowable stress 1.0 g / cm, maximum allowable stress 500 g / cm, maximum additional strain 200%, strain adjustment 200%), GAP after sample setting Loss modulus (G''), storage modulus (G') and tangent loss (tan δ) can be measured in the range of FORCE from 0 to 100 gm.

<Toner Manufacturing Method>
Conventionally known methods such as a melt-kneading-pulverization method and a polymerization method can be applied as the method for producing the toner set of the present embodiment. The same manufacturing method may be used for the color toner and the IR toner, or different manufacturing methods may be used, such as a polymerization method for the color toner and a melt-kneading pulverization method for the IR toner.

<<Melt-kneading-pulverization method>>
In the melt-kneading-pulverization method, the production steps include (1) a step of melt-kneading at least a binder resin, a colorant or a near-infrared light absorbing material, and a release agent; (3) externally adding inorganic fine particles; From the viewpoint of cost, it is preferable to side-knead the fine powder to be duplicated in the pulverization/classification step of step (2) as the raw material of step (1).

As a kneader used for kneading, a closed kneader, a single-screw or twin-screw extruder, an open-roll kneader, or the like can be used. Types of kneaders include, for example, KRC Kneader (manufactured by Kurimoto Iron Works Co., Ltd.), Bus Co Kneader (manufactured by Buss), TEM extruder (manufactured by Toshiba Machine Co., Ltd.), TEX twin-screw kneader (Japan Steel Co., Ltd.), PCM kneader (manufactured by Ikegai Ironworks Co., Ltd.), three-roll mill, mixing roll mill, kneader (manufactured by Inoue Seisakusho), Kneedex (manufactured by Mitsui Mining Co., Ltd.), MS type pressure kneader, Kniderruder (Moriyama Seisakusho Co., Ltd.), Banbury Mixer (manufactured by Kobe Steel, Ltd.), and the like.

Examples of pulverizers include counter jet mill, micron jet, inomizer (manufactured by Hosokawa Micron Corporation), IDS type mill, PJM jet pulverizer (manufactured by Nippon Pneumatic Industry Co., Ltd.), cross jet mill (manufactured by Kurimoto Iron Works Co., Ltd.), ur Max (manufactured by Nisso Engineering), SK Jet-O-Mill (manufactured by Seishin Enterprise), Crypton (manufactured by Kawasaki Heavy Industries), Turbo Mill (manufactured by Turbo Industries), Super Rotor (manufactured by Nisshin Engineering), etc. mentioned.
Classifiers include, for example, Classile, Micron Classifier, Specdic Classifier (manufactured by Seishin Enterprise Co., Ltd.), Turbo Classifier (manufactured by Nisshin Engineering Co., Ltd.), Micron Separator, Turboplex (ATP), TSP Separator (Hosokawa Micron Corporation (manufactured by Nittetsu Mining Co., Ltd.), Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Industrial Co., Ltd.), and YM Microcut (manufactured by Yasukawa Shoji Co., Ltd.).
Examples of sieving devices used for sieving coarse particles include Ultrasonic (manufactured by Koei Sangyo Co., Ltd.), Resona Sieve, Gyro Shifter (Tokuju Kosakusho Co., Ltd.), Vibrasonic System (manufactured by Dalton), Soni Clean ( Sintokogyo Co., Ltd.), turbo screener (manufactured by Turbo Industry Co., Ltd.), micro shifter (manufactured by Makino Sangyo Co., Ltd.), circular vibrating screen, and the like.

<<polymerization method>>
A conventionally known method can be used as the polymerization method. The polymerization method includes, for example, the following procedures. First, a toner material liquid (oil phase) is prepared by dispersing a colorant, a binder resin, and a release agent in an organic solvent. It is preferable that the polyester prepolymer (A) having an isocyanate group is added to the toner material liquid and reacted during granulation so that the toner contains the urea-modified polyester resin.

Next, the toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and fine resin particles.
As for the aqueous medium, the aqueous solvent used for the aqueous medium may be water alone or may contain an organic solvent such as alcohol.
The amount of the aqueous solvent used relative to 100 parts by mass of the toner material liquid is preferably 50 parts by mass to 2,000 parts by mass, more preferably 100 parts by mass to 1,000 parts by mass.
The resin fine particles are not particularly limited as long as they are resins capable of forming an aqueous dispersion, and can be appropriately selected according to the purpose. Examples thereof include vinyl resins, polyurethane resins, epoxy resins, and polyester resins. be done.

After dispersion, the organic solvent is removed from the emulsified dispersion (reactant), followed by washing and drying to obtain toner base particles.

IR toners and color toners can be used both as single-component developers and as two-component developers.
When the toner of the present embodiment is used in a two-component developer, it may be used by mixing with a magnetic carrier. parts to 10 parts by mass are preferred.
As the magnetic carrier, conventionally known ones can be used, and examples thereof include iron powder, ferrite powder, magnetite powder, magnetic resin carrier, etc. having a particle size of about 20 μm to 200 μm.
A coated magnetic carrier can also be used. Coating materials for coating the magnetic carrier include, for example, amino-based resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin; polyvinylidene-based resins such as polyvinyl; polystyrene resins such as polymethyl methacrylate resins, polyacrylonitrile resins, polyvinyl acetate resins, polyvinyl alcohol resins, polyvinyl butyral resins, polystyrene resins, and styrene acrylic copolymer resins; halogenated olefin resins such as polyvinyl chloride; polyethylene terephthalate resins; Polyester resin such as polybutylene terephthalate resin; Polycarbonate resin, polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoropropylene resin, vinylidene fluoride and acrylic monomer copolymers, copolymers of vinylidene fluoride and vinyl fluoride, fluoroterpolymers such as terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers, and silicone resins.
Furthermore, if necessary, conductive powder or the like may be contained in the coating resin. As the conductive powder, metal powder, carbon black, titanium oxide, tin oxide, zinc oxide and the like can be used. These conductive powders preferably have an average particle size of 1 μm or less. If the average particle size is 1 μm or less, it is possible to prevent the problem of difficulty in controlling electrical resistance.

(Image forming apparatus and image forming method)
The image forming apparatus of this embodiment includes an electrostatic latent image carrier, an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and a toner image by developing the electrostatic latent image. developing means comprising IR toner for forming an IR toner image and color toner for forming a color toner image; transfer means for transferring the toner image to a recording medium; and transfer transferred to the recording medium fixing means for fixing the image, and other means appropriately selected as necessary.
The image forming method of the present embodiment includes an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image carrier, a developing step of developing the electrostatic latent image to form a toner image, a toner It includes a transfer step of transferring an image onto a recording medium and a fixing step of fixing the transferred image transferred onto the recording medium, and further has other steps appropriately selected as necessary.
The image forming method of this embodiment can be suitably carried out by the image recording apparatus of this embodiment.

In the image forming method and image forming apparatus, when the IR toner image is a solid image, the 60 degree glossiness of the solid image is 30 or more, preferably 30 or more and 80 or less, and more preferably 30 or more and 60 or less.
In one example of the image forming method and image forming apparatus, the 60-degree glossiness of the solid image when the IR toner image is a solid image is 10 times higher than the 60-degree glossiness of the solid image when the color toner image is a solid image. 15 or more, preferably 15 or more, and more preferably 20 or more.
In another example of the image forming method and image forming apparatus, the tangent loss (tan δi) of the IR toner at 100° C. to 140° C. is preferably 2.5 or more, more preferably 3.0 or more. In the image forming method and image forming apparatus, the tangent loss (tan δc) of the color toner is preferably 2 or less.

It is preferable that the IR toner image is formed closer to the recording medium than the color toner image is on the recording medium. As a method of forming the IR toner image closer to the recording medium than the color toner image is, for example, a method of forming the IR toner image on the recording medium and then forming the color toner image can be mentioned.
The number of color toners used for forming a color toner image is not particularly limited, and can be appropriately selected according to the purpose. When a plurality of color toners are used, a method of simultaneously forming a plurality of color toners or a method of repeatedly forming single-color toners and layering each color can be performed. is preferred. In the color toner image, there are no particular restrictions on the order in which the respective colors are formed.

The IR toner adhesion amount in the IR toner image is preferably 0.30 mg/cm ² or more and 0.45 mg/cm ² or less, more preferably 0.35 mg/cm ² or more and 0.40 mg/cm ² or less. When the amount of the IR toner adhered is 0.30 mg/cm ² or more, the substrate hiding rate of the image becomes sufficient, and a stable image can be obtained.
Further, the near-infrared light absorbing material has some absorption in the visible light region and is not completely colorless. Therefore, if the amount of the near-infrared light absorbing material added to the toner increases, the visibility increases. Therefore, the visibility can be reduced by setting the IR toner adhesion amount of the image to 0.45 mg/cm ² or less.

The toner adhesion amount per unit area of the color toner image superimposed on the IR toner image is preferably 30% or more and 80% or less. When the toner adhesion amount per unit area of the color toner image is within this numerical range, the visibility of the IR toner image under the color toner image can be sufficiently reduced, which is preferable.
The reason for this is as follows. The IR toner of the present embodiment has some absorption in the visible light region, and a monochromatic image is not completely transparent. Therefore, in order to make IR image information invisible (to make it difficult to see), it is preferable to mask with color toner. If the toner adhesion amount per unit area of the color toner image is 30% or more, it is effective to prevent the problem that the IR toner image becomes easily visible. If the toner adhesion amount per unit area of the color toner image is less than 30%, the visibility of the IR toner image is increased especially when the yellow toner is overlaid.

An image forming method in which the toner adhesion amount per unit area of the color toner image on the IR toner image is 30% or more and 80% or less is particularly effective when two-dimensional code images are superimposed to form an image. By superimposing a two-dimensional code image with IR toner and a two-dimensional code image with color toner, which have different information, images can be obtained within the same image area by using reading devices with different light wavelengths (860 nm and 532 nm, respectively). , more information can be embedded than in the case of only a two-dimensional code image with color toner.
It is preferable that the two-dimensional code image (i), which is an IR toner image, is formed closer to the recording medium than the two-dimensional code image (c), which is a color toner image, on the recording medium. At this time, when the color toner image is a solid image, the absorbance of the solid image at 800 nm or more and 900 nm or less is preferably less than 0.05, more preferably less than 0.01.
Moreover, it is preferable that the information possessed by the two-dimensional code image (i) is different from the information possessed by the two-dimensional code image (c).

When the two-dimensional code image of IR toner and the two-dimensional code image of color toner are superimposed, it is possible to use the two-dimensional code image of color toner as a dummy code. In such a form, the two-dimensional code image of the IR toner can be read only by a two-dimensional code reader of infrared light without being visually recognized, and the two-dimensional code image of the color toner is visually recognized. , the information cannot be read by a two-dimensional code reader using infrared light.

Examples of the toner used in this embodiment will be described below, but the toner that can be used in this embodiment is not limited to these examples. "Parts" means "parts by mass" unless otherwise specified.

<Production of IR Toner 1>
- Polyester resin 1 (RN-306SF, manufactured by Kao Corporation, weight average molecular weight Mw 7,700, acid value 4 mgKOH / g) 80 parts - Polyester resin 2 (RN-300SF, manufactured by Kao Corporation, weight average molecular weight Mw 11,000, Acid value 4 mgKOH/g) 10 parts Wax dispersant (EXD-001, manufactured by Sanyo Kasei Co., Ltd.) 4 parts Monoester wax 1 (melting point mp 70.5 ° C.) 6 parts Salicylic acid derivative zirconium salt A 0.9 parts Vanadylnaphthalocyanine 0.3 parts The vanadylnaphthalocyanine used as the near-infrared absorbing material was the compound of the following structural formula (1), and the salicylic acid derivative zirconium salt A was the compound of the following structural formula (2).

L ₁ in Structural Formula (2) has the following structure.

The toner raw materials of the composition are premixed using a Henschel mixer (manufactured by Nippon Coke Kogyo Co., Ltd., FM20B), and then melted and kneaded at a temperature of 100 to 130° C. with a uniaxial kneader (manufactured by Buss, Kokneader kneader). did.
The resulting kneaded product was cooled to room temperature and then coarsely pulverized to 200 μm to 300 μm by Rotoplex.
The coarsely pulverized particles are finely pulverized using a counter jet mill (100AFG, manufactured by Hosokawa Micron Corporation) while adjusting the pulverization air pressure appropriately so that the weight average particle size is 4.5±0.3 μm. Air classifier (manufactured by Matsubo Co., Ltd., EJ-LABO), the louver is opened so that the weight average particle size is 5.2 ± 0.2 μm and the weight average particle size / number average particle size ratio is 1.20 or less. Toner base particles 1 were obtained by classifying while appropriately adjusting the degree.
Next, 1.3 parts of fumed silica (ZD-30ST, manufactured by Tokuyama Co., Ltd.) and 1.5 parts of fumed silica (UFP-35HH, manufactured by Denki Kagaku Co., Ltd.) are added to 100 parts of toner base particles 1. and 1.0 part of titanium dioxide (MT-150AFM, manufactured by Tayca Corporation) were stirred and mixed in a Henschel mixer to prepare IR toner 1.

<Production of IR Toner 2>
IR Toner 2 was produced in the same manner as IR Toner 1, except that vanadyl naphthalocyanine was changed to 0.6 parts.

<Production of IR Toner 3>
IR Toner 3 was produced in the same manner as IR Toner 1, except that vanadyl naphthalocyanine was changed to 1.0 part.

<Production of IR Toner 4>
IR Toner 4 was produced in the same manner as IR Toner 2, except that in IR Toner 2, Polyester Resin 2 was changed to Polyester Resin 3 (RN-290SF, Mw 87,000, acid value 28 mgKOH/g, manufactured by Kao Corporation). did.
The polyester resin 3 is a resin synthesized from bisphenol A-polyethylene oxide addition alcohol, bisphenol A-ethylene oxide addition alcohol, fumaric acid, and trimellitic anhydride.

<Production of IR Toner 5>
IR Toner 5 was produced in the same manner as IR Toner 4, except that in IR Toner 4, polyester resin 1 was changed to 70 parts and polyester resin 3 was changed to 20 parts.

<Production of IR Toner 6>
0.3 parts of vanadyl naphthalocyanine of IR toner 4 was used, and the weight average particle size of the toner base particles was adjusted to 6.8±0.2 μm in the pulverization/classification process.
Then, 0.8 parts of fumed silica (ZD-30ST, manufactured by Tokuyama Co., Ltd.), 1.0 part of fumed silica (UFP-35HH, manufactured by Denki Kagaku Co., Ltd.), and titanium dioxide are added to 100 parts of the toner base particles. (MT-150AFM, manufactured by Tayca Co., Ltd.) was stirred and mixed with a Henschel mixer to prepare IR toner 6.

<Production of IR Toner 7>
IR Toner 7 was produced in the same manner as IR Toner 6, except that vanadyl naphthalocyanine was changed to 0.6 parts.

<Production of IR Toner 8>
IR Toner 8 was produced in the same manner as IR Toner 5, except that in IR Toner 5, the salicylic acid derivative zirconium salt A was changed to 1.5 parts.

<Production of IR Toner 9>
In the pulverization/classification process of IR toner 4, the weight average particle diameter was set to 8.0±0.2 μm.
Next, to 100 parts of the toner base particles, 0.6 parts of fumed silica (ZD-30ST, manufactured by Tokuyama Corporation), 0.8 parts of fumed silica (UFP-35HH, manufactured by Denki Kagaku Co., Ltd.), titanium dioxide ( MT-150AFM (manufactured by Tayca Co., Ltd.) was stirred and mixed with a Henschel mixer to prepare IR toner 9.

<Production of IR Toner 10>
IR Toner 10 was produced in the same manner as IR Toner 1, except that vanadyl naphthalocyanine was changed to 0.2 parts.

<Production of IR Toner 11>
IR Toner 11 was produced in the same manner as IR Toner 4 except that vanadyl naphthalocyanine was changed to 1.2 parts.

<Production of IR Toner 12>
IR Toner 12 was produced in the same manner as IR Toner 4, except that in IR Toner 4, Polyester Resin 1 was changed to 60 parts and Polyester Resin 3 to 30 parts.

<Production of IR Toner 13>
IR Toner 6 was prepared in the same manner as IR Toner 6, except that 0.3 parts of vanadyl naphthalocyanine was changed to 1.0 parts of near-infrared absorbing dye 1 (OPTLION NIR-761 manufactured by Toyocolor Co., Ltd.). , IR toner 13 was produced.

<Production of IR Toner 14>
IR Toner 6 was prepared in the same manner as IR Toner 6, except that 0.3 parts of vanadyl naphthalocyanine was changed to 2.0 parts of near-infrared absorbing dye 1 (OPTLION NIR-761 manufactured by Toyocolor Co., Ltd.). , IR Toner 14 was produced.

<Production of two-component developer>
<<Preparation of carrier>>
・Silicone resin (organo straight silicone) 100 parts ・Toluene 100 parts ・γ-(2-aminoethyl)aminopropyltrimethoxysilane 5 parts ・Carbon black 10 parts Disperse the mixture for 20 minutes with a homomixer to form a coating layer. A liquid was prepared. A coating layer forming liquid is prepared using a fluid bed type coating apparatus so that Mn ferrite particles having a weight average particle diameter of 35 μm are used as a core material and the average film thickness on the surface of the core material is 0.20 μm. Coating and drying were carried out while controlling the temperature in the bath at 70°C. The obtained carrier was fired in an electric furnace at 180° C. for 2 hours to obtain a carrier.

<<Preparation of developer (two-component developer)>>
Each of the prepared IR toners 1 to 14 and each of the perylene black toners 1 and 2 and a carrier were uniformly mixed and charged at 48 rpm for 5 minutes using a Turbula mixer (manufactured by Willie & Bakkofen (WAB)). , developers 1 to 14, and perylene black developers 1 and 2, respectively.
The mixing ratio of the toner and the carrier was adjusted to match the toner concentration of the initial developer of the evaluation machine: 5% by mass.

(Examples 1-12, Comparative Examples 1-2)
In a digital full-color multifunction machine (Imagio Neo C600, manufactured by Ricoh Co., Ltd., hereinafter abbreviated as "neo C600") having four colors of black developer, yellow developer, magenta developer, and cyan developer, black developer was replaced with each of the two-component developers 1 to 14, and the apparatus was equipped with a toner set containing IR toner and color toner.
The color toners (yellow, magenta, and cyan) contained in the yellow developer, magenta developer, and cyan developer had an absorbance of less than 0.01 at a wavelength of 800 nm or longer.

<Measurement of absorbance>
A solid patch was printed on an OHP film (type PPC-FC, manufactured by Ricoh Co., Ltd.) using neo C600 so that the toner adhesion amount was 0.5 mg/cm ² . The solid patch was measured for spectral transmittance T from 800 nm to 900 nm using a spectrophotometer (V-660DS, manufactured by JASCO Corporation), using an OHP film on which no image was output as a blank. From the obtained spectral transmittance T, the absorbance A was calculated according to the following formula (1).
A = -log T (1)

(Adherence amount evaluation, glossiness evaluation)
Ricoh Co., Ltd. PPC paper TYPE 6000 (70 W) was used as the paper, and a 5 cm×5 cm solid patch of each color toner was first printed. The adhesion amount and glossiness (60 degree glossiness) of the color toner at that time are shown in Table 2 below.

<Adhesion amount evaluation>
The fixing unit of neo C600 was removed, and an unfixed solid patch of 5 cm×5 cm was output. The solid patch portion was cut out with scissors to prepare a cut piece. The mass of the prepared cut piece was measured with a precision balance, the toner in the solid patch portion (unfixed image) was blown off with an air gun, and the mass of the cut piece was measured. The toner adhesion amount was calculated using the following formula from the mass values before and after the toner was blown off with an air gun. The results are shown in Table 1 below.
Adhesion amount of toner (mg/cm ² )=((weight of cutout piece with solid patch)−(weight of cutout piece after blowing off))/25

<Glossiness evaluation>
A fixed solid patch of 5 cm×5 cm output by neo C600 was measured at four points using a gloss meter (VGS-1D, manufactured by Nippon Denshoku Industries Co., Ltd.). The average value of the evaluation results at four points was calculated and defined as the glossiness. The results are shown in Table 1 below.

(visibility evaluation, readability evaluation)
Visibility evaluation and readability evaluation were performed as follows.
Using the device and paper shown in Table 3, a QR code (registered trademark) is printed with IR toner, and the pattern shown in FIG. 10 is printed thereon, and the QR code hidden by the pattern as shown in FIG. A registered trademark) image was created.
In addition, the image shown in FIG. 12 has an image portion (region A in FIG. 12) in which a QR code (registered trademark) is printed with IR toner in a portion where the entirety is colored, and a QR code ( (Registered Trademark)) and an image portion (region B in FIG. 12) in which a QR Code (Registered Trademark) with information different from the QR Code (Registered Trademark) printed with color toner is printed with IR toner.
11 and 12, the visibility of the IR toner image and the readability of the QR code (registered trademark) in the image output with the IR toner were evaluated. Table 3 shows the results. Note that in FIG. 11, the IR toner image, which is originally invisible, is visualized and displayed.

<Visibility evaluation>
2 or less people could see the QR code (registered trademark) consisting of an IR image in the printed matter of FIG. was rated as △, and the case of 6 or more people was rated as x.

<Readability evaluation>
11 and 12 were output 10 sheets each, and a QR code (registered trademark) consisting of all IR images formed in the output image was read by a two-dimensional barcode reader (model number: CM-2D200K2B, Avock). 870nm band pass filter (870nm BPF manufactured by Ceratec Japan Co., Ltd.) is read by the product), and all QR codes (registered trademark) can be read in one scan ○, all QR codes (registered (trademark) was read, but the QR code (registered trademark) that was scanned multiple times was evaluated as Δ, and the case where even one could not be read was evaluated as ×.

(Example 13)
A printer (manufactured by Ricoh Co., Ltd.) having four colors of yellow toner, magenta toner, cyan toner, and black toner was used. The black toner of the printer was replaced with IR toner 2 to make a toner set containing IR toner and color toner.
The absorbance of the color toners (yellow, magenta, and cyan) at wavelengths above 800 nm was less than 0.01.
As the paper, COTED glossy paper (135 g/m ² , manufactured by Mondi) was used. Using each color of color toner, a solid patch of 5 cm×5 cm was printed on paper, and the adhesion amount and glossiness of each color toner were measured in the same manner as described above. Table 4 shows the measurement results.
11 and 12 were output, and the visibility and readability of the IR toner image were similarly evaluated. Table 4 shows the results.

(Comparative Example 3)
Evaluation was performed in the same manner as in Example 13, except that the IR toner used was replaced with IR toner 12 and a toner set containing IR toner and color toner was used. Table 4 shows the evaluation results.

(Example 14)
Evaluation was performed in the same manner as in Example 13, except that the IR toner used was replaced with IR toner 13 and a toner set containing IR toner and color toner was used. Table 4 shows the evaluation results.

In Tables 1 to 4, "*device, paper 1" and "*device, paper 2" refer to the following devices and paper.
The device and paper 1 are Ricoh's 4-color tandem machine, and the paper is Ricoh PPC paper TYPE 6000 (70 W).
The device and the paper 2 are a Ricoh 4-color tandem machine and the paper is COTED glossy paper.

In addition, "judgment" in Tables 3 and 4 is "○" when both visibility and reading accuracy are "○", and "△" when either one has an evaluation result of "△" ", and when there was "x" in either one, it was evaluated as "x". If the judgment is "○", it indicates that the visibility and reading accuracy are good, and if it is "△", the visibility and reading accuracy are insufficient, but there is no problem in use, If it is "x", it indicates that the visibility and reading accuracy are insufficient and there is a problem in use.

As described above, the toner set, the developer, and the image forming method of the present embodiment can produce a visible image provided together with an IR image on the surface of an image output medium in a relatively low-gloss image that makes use of the features of electrophotography. To be provided in an arbitrary region regardless of the region in which the IR image and the visible image on the surface of the image output medium are provided without impairing the image quality of the visible image when visually observed and in which information can be recorded at high density. It is possible to provide a toner set, an image forming method, and an image forming apparatus capable of obtaining an IR image capable of

What has been described above is only an example, and each of the following aspects has a unique effect.
[First aspect]
In the first mode, a color toner image made of at least one of yellow, magenta, and cyan color toners and a special toner image (for example, IR toner image) made of special toner (for example, IR toner) are recorded on the same recording medium (for example, paper P). ), and fix the color toner image and the special toner image on the recording medium by a fixing means (for example, a fixing device 21) to form an image. and in the case of the special image forming operation of forming the special toner image, the amount per unit area on the recording medium is higher than that of the normal image forming operation of forming the same color toner image without forming the special toner image. It is characterized by having control means (for example, a control section 30) that performs toner amount suppression control to reduce the amount of color toner.
In the first mode, when a color toner image is formed in a special image forming operation using color toner and special toner, the same color toner image is formed in a normal image forming operation without using special toner by the toner amount suppression control. The amount of color toner per unit area is smaller than in the case of As a result, during the special image forming operation, the total amount of toner per unit area in the toner image portion where both the color toner and the special toner are adhered can be kept small, and fixing failure can be suppressed in a single fixing process. Image formation can be completed. Therefore, it is possible to shorten the time required for image formation using special toners and color toners.

[Second aspect]
In a second aspect based on the first aspect, in the case of the special image forming operation, the control means fixes the toner image made up of the color toner image and the special toner image so that the total amount of toner per unit area is fixed once. input image information so that the total amount of toner in the unfixable portion is equal to or less than the upper limit of fixation. It is characterized in that the toner amount suppression control is performed by performing image processing (for example, total toner amount regulation processing) on the toner.
In the second aspect, during the special image forming operation, an image can be formed by setting the non-fixable portion where the total toner amount per unit area exceeds the fixable upper limit fixable in one fixing process to the fixable upper limit value or less. Therefore, image formation can be completed by one fixing process while suppressing fixing failure.

[Third aspect]
In a third aspect based on the second aspect, in the image processing, for the unfixable portion, the amount of color toner is made smaller than that during the normal image forming operation so that the total amount of toner is equal to or less than the upper fixing limit. 3. The color toner amount for the portion other than the unfixable portion is kept the same as during the normal image forming operation.
In the third mode, the amount of color toner in the portion other than the unfixable portion remains the same as that in the normal image forming operation, and image quality change in the portion other than the unfixable portion can be suppressed.

[Fourth aspect]
According to a fourth aspect, in any one of the first to third aspects, the normal color data used during the normal image forming operation is used as the color conversion data for converting the color information of the input image information into the color information for the image forming apparatus. Storage means (for example, the storage unit 32) for storing color conversion data (for example, a color conversion separation table) and special color conversion data (for example, a color conversion separation table and a toner adhesion amount conversion table) used when performing the toner amount suppression control. ), wherein the control means forms an image from the input image information color-converted using the normal color conversion data during the normal image forming operation, and performs the special color conversion when performing the toner amount suppression control. It is characterized in that an image is formed from input image information that has undergone color conversion using data.
In the fourth aspect, toner amount suppression control can be implemented relatively easily.

[Fifth aspect]
A fifth aspect is any one of the first to fourth aspects, wherein, in the case of the special image forming operation, the control means controls the fixing ability of the fixing means to be higher than that in the normal image forming operation, or (1) fixing condition change control is performed so as to lengthen the fixing processing time by the fixing means, or both.
In the fifth aspect, the fixing condition change control can increase the fixing upper limit value at which the total amount of toner per unit area can be fixed in one fixing process. As a result, it is possible to reduce the extent to which the amount of color toner per unit area is reduced by toner amount suppression control, thereby suppressing changes in image quality.

[Sixth aspect]
In a sixth aspect based on the fifth aspect, in the case of the special image forming operation, the controller controls that the toner image composed of the color toner image and the special toner image has a total toner amount per unit area of the normal image forming operation. If it is determined that the toner excess portion exceeding the upper limit value (for example, the first specified value) of the color toner amount at the time is included, the fixing condition change control is performed, and if it is determined that the toner excess portion is not included (3) is characterized in that the fixing condition change control is not performed.
In the sixth aspect, if it is determined that the total toner amount per unit area does not include an excess toner portion exceeding the upper limit of the color toner amount in normal image forming operation, the fixing condition change control is not performed. It is possible to suppress adverse effects caused by changing fixing conditions.

[Seventh aspect]
In a seventh aspect, a color toner image made of at least one of yellow, magenta, and cyan color toners and a special toner image made of special toner are formed on the same recording medium, and the color toner image and the special toner image are formed. is fixed on the recording medium by a fixing means to form an image. The fixing ability of the fixing means is increased, or the fixing processing time by the fixing means is increased, or both, as compared with the normal image forming operation for forming the same color toner image. It is characterized by having control means for performing fixing condition change control.
In the seventh aspect, when a color toner image is formed in a special image forming operation using color toner and special toner, the same color toner image is formed in a normal image forming operation without using special toner by the fixing condition change control. The fixing ability is improved, the fixing processing time is lengthened, or both are realized. As a result, even if there is a toner image portion with a large total amount of toner per unit area, which cannot be fixed by one fixing process under the fixing conditions during normal image forming operation, fixing failure can be suppressed by one fixing process. Image formation can be completed. Therefore, it is possible to shorten the time required for image formation using special toners and color toners.

[Eighth aspect]
In an eighth aspect based on the seventh aspect, in the case of the special image forming operation, the controller controls that the toner image composed of the color toner image and the special toner image has a total toner amount per unit area of the normal image forming operation. If it is determined that the toner excess portion exceeding the upper limit value of the color toner amount at the time is included, the fixing condition change control is performed, and if it is determined that the toner excess portion is not included, the fixing condition change is performed. It is characterized by not performing control.
In the eighth mode, if it is determined that the total toner amount per unit area does not include an excess toner portion exceeding the upper limit of the color toner amount in the normal image forming operation, the fixing condition change control is not performed. It is possible to suppress adverse effects caused by changing fixing conditions.

[Ninth aspect]
A ninth aspect is characterized in that, in any one of the first to eighth aspects, the special toner is a special color toner that forms an image that is difficult to visually recognize on a recording medium.
In the ninth aspect, it is possible to shorten the time required to form an image that is difficult to be visually recognized.

[Tenth Aspect]
A tenth aspect is characterized in that in any one of the first to ninth aspects, the special toner is transparent infrared light absorbing toner (for example, IR toner).
In the tenth aspect, it is possible to shorten the time required to form an image difficult to see using the infrared light absorbing toner.

[11th aspect]
An eleventh aspect is the tenth aspect, wherein the color toner contains a binder resin and a colorant, the infrared light absorbing toner contains a binder resin and a near-infrared light absorbing material, and the 60-degree The glossiness is 30 or higher, and the 60-degree glossiness of the solid image is higher than the 60-degree glossiness of the solid image of the color toner by 10 or more.
In the eleventh aspect, it is possible to suppress an increase in the visibility of an image that is difficult to see due to the infrared light absorbing toner.

[Twelfth aspect]
A twelfth aspect is the tenth or eleventh aspect, wherein the infrared light-absorbing toner contains a binder resin and a near-infrared light-absorbing material, and has a tangent loss (tan δi ) is 2.5 or more, the color toner contains a binder resin and a colorant, and has a tangent loss (tan δc) of 2 or less within the range of 100° C. to 140° C. It is.
In the twelfth aspect, it is possible to stably ensure the reading accuracy of the difficult-to-recognize image with the infrared light absorbing toner.

[13th aspect]
A thirteenth aspect is the toner according to any one of the tenth to twelfth aspects, wherein the infrared light absorbing toner has a weight average particle diameter of 5 μm or more and 7 μm or less.
In the thirteenth mode, a high quality image can be obtained with the infrared light absorbing toner.

[14th aspect]
A fourteenth aspect is the image forming apparatus according to any one of the tenth to thirteenth aspects, wherein the color toner has an absorbance of less than 0.05 at 800 nm or more of the solid image.
In the fourteenth aspect, it is possible to stably ensure reading accuracy of an image that is difficult to be visually recognized by the infrared light absorbing toner.

[15th aspect]
A fifteenth aspect is characterized in that, in any one of the tenth to fourteenth aspects, the special toner image made of the infrared light absorbing toner is formed on the recording medium closer to the recording medium than the color toner image is. and
In the fifteenth aspect, it is possible to suppress an increase in the visibility of an image that is difficult to see due to the infrared light absorbing toner.

[16th aspect]
A sixteenth aspect is a two-dimensional code image (i) consisting of the special toner image and a two-dimensional code image (i) consisting of the solid image of the color toner image showing mutually different information by the special image forming operation in the fifteenth aspect. c) is superimposed and the solid image of the color toner image has an absorbance of less than 0.05 at 800 nm or more and 900 nm or less.
In the sixteenth aspect, it is possible to stably ensure the reading accuracy of the two-dimensional code image (i) made of the special toner image.

[17th aspect]
A seventeenth aspect is any one of the first to sixteenth aspects, wherein in the case of the special image forming operation, the controller controls that the special toner amount per unit area of the special toner image is 0.30 mg/cm ² or more. .45 mg/cm ² or less, and the special toner amount per unit area in the special toner image is set to be smaller than the color toner amount per unit area in the color toner image. It is something to do.
In the seventeenth aspect, it is possible to stably ensure the reading accuracy of the difficult-to-recognize image.

[18th aspect]
In the eighteenth mode, a color toner image made of at least one of yellow, magenta, and cyan color toners and a special toner image made of special toner are formed on the same recording medium, and the color toner image and the special toner image are formed. is fixed on the recording medium by a fixing means to form an image. It is characterized in that the image density of the image is lower.
In the eighteenth mode, when a black image is formed using the color toner and the special toner, the amount of color toner per unit area is smaller than when the same black image is formed without using the special toner. As a result, the total amount of toner per unit area in the toner image area where both color toner and special toner adhere can be kept low, making it possible to complete image formation in a single fixing process while suppressing poor fixing. becomes. Therefore, it is possible to shorten the time required for image formation using special toners and color toners.

[Other aspects]
In another aspect, a color toner image made of at least one of yellow, magenta, and cyan color toners and a special toner image made of special toner are formed on the same recording medium, and the color toner image and the special toner are formed. In an image forming method for forming an image by fixing an image on the recording medium by fixing means, in the case of a special image forming operation for forming the color toner image and the special toner image, the special toner image is not formed. It is characterized in that the amount of color toner per unit area on the recording medium is smaller than that in the normal image forming operation in which the same color toner image is formed on the recording medium.
In another aspect, a color toner image made of at least one of yellow, magenta, and cyan color toners and a special toner image made of special toner are formed on the same recording medium, and the color toner image and the special toner image are formed on the same recording medium. In an image forming method for forming an image by fixing a special toner image on the recording medium by a fixing means, in the case of a special image forming operation for forming the color toner image and the special toner image, the special toner image is formed. The fixing ability of the fixing means is increased, or the fixing processing time by the fixing means is increased, or both of them, compared to the normal image forming operation in which the same color toner image is formed without the fixing means. It is characterized by making it
In another aspect, a color toner image made of at least one of yellow, magenta, and cyan color toners and a special toner image made of special toner are formed on the same recording medium, and the color toner image and the special toner image are formed on the same recording medium. In an image forming method for forming an image by fixing a special toner image on the recording medium by a fixing means, the image density of the color toner image and the special toner image is higher than that of a black image formed only of the color toner image. It is characterized in that the formed black image has a lower image density.

1: Image forming section 2: Transfer section 3: Recording medium supply section 4: Fixing section 5: Recording medium discharge section 6: Process unit 7: Photoreceptor 8: Charging roller 9: Developing device 11: Exposure device 12: Intermediate transfer belt 13: Primary Transfer Roller 14: Secondary Transfer Roller 18: Paper Feed Cassette 21: Fixing Device 22: Fixing Roller 23: Pressure Roller 24: Paper Discharge Roller 25: Paper Discharge Tray 26: Toner Cartridge 27: Waste Toner Container 30 : Control unit 31: Main control unit 32: Storage unit 33: Decomposition processing unit 34: Gamma conversion unit 35: Total toner amount regulation unit 36: Gradation conversion unit 40: Image formation control unit 100: Apparatus body 101: Cover member 102: Container holding member

JP 2016-158161 A

Claims (17)

A color toner image made of at least one color toner of yellow, magenta, and cyan and an infrared light absorbing toner image made of infrared light absorbing toner are formed on the same recording medium, and the color toner image and the infrared light are formed. In an image forming apparatus that forms an image by fixing a light-absorbing toner image on the recording medium by a fixing means,
In the case of the special image forming operation for forming the color toner image and the infrared light absorbing toner image, the normal image forming operation for forming the same color toner image without forming the infrared light absorbing toner image is performed. also has control means for performing toner amount suppression control to reduce the amount of color toner per unit area on the recording medium;
the infrared light absorbing toner image is formed on the recording medium closer to the recording medium than the color toner image ;
The image forming apparatus , wherein the infrared light absorbing toner is transparent and has a weight average particle diameter of 5 μm or more and 7 μm or less . The image forming apparatus according to claim 1,
The infrared light-absorbing toner contains a binder resin and a near-infrared light-absorbing material, and has a tangent loss (tan δi) of 2.5 or more within the range of 100° C. or more and 140° C. or less,
The image forming apparatus, wherein the color toner contains a binder resin and a colorant, and has a tangent loss (tan δc) of 2 or less within the range of 100° C. or higher and 140° C. or lower. A color toner image made of at least one of yellow, magenta, and cyan color toners and an infrared light absorbing toner image made of infrared light absorbing toner are formed on the same recording medium, and the color toner image and the infrared light are formed. In an image forming apparatus that forms an image by fixing a light-absorbing toner image on the recording medium by a fixing means,
In the case of the special image forming operation for forming the color toner image and the infrared light absorbing toner image, the normal image forming operation for forming the same color toner image without forming the infrared light absorbing toner image is performed. also has control means for performing toner amount suppression control to reduce the amount of color toner per unit area on the recording medium;
forming the infrared light absorbing toner image on the recording medium closer to the recording medium than the color toner image;
The infrared light-absorbing toner has transparency, contains a binder resin and a near-infrared light-absorbing material, and has a tangent loss (tan δi) of 2.5 or more in the range of 100° C. or higher and 140° C. or lower. can be,
The image forming apparatus, wherein the color toner contains a binder resin and a colorant, and has a tangent loss (tan δc) of 2 or less within the range of 100° C. or higher and 140° C. or lower. The image forming apparatus according to any one of claims 1 to 3,
In the case of the special image forming operation, the control means controls the amount of infrared light absorbing toner per unit area of the infrared light absorbing toner image to be 0.30 mg/cm. ² More than 0.45mg/cm ² and the amount of infrared light absorbing toner per unit area in the infrared light absorbing toner image is smaller than the amount of color toner per unit area in the color toner image. image forming apparatus. A color toner image made of at least one color toner of yellow, magenta, and cyan and an infrared light absorbing toner image made of infrared light absorbing toner are formed on the same recording medium, and the color toner image and the infrared light are formed. In an image forming apparatus that forms an image by fixing a light-absorbing toner image on the recording medium by a fixing means,
In the case of the special image forming operation for forming the color toner image and the infrared light absorbing toner image, the normal image forming operation for forming the same color toner image without forming the infrared light absorbing toner image is performed. also has control means for performing toner amount suppression control to reduce the amount of color toner per unit area on the recording medium;
forming the infrared light absorbing toner image on the recording medium closer to the recording medium than the color toner image;
In the case of the special image forming operation, the control means controls the amount of infrared light absorbing toner per unit area of the infrared light absorbing toner image to be 0.30 mg/cm. ² More than 0.45mg/cm ² and the amount of infrared light absorbing toner per unit area in the infrared light absorbing toner image is smaller than the amount of color toner per unit area in the color toner image. image forming apparatus. In the image forming apparatus according to claim 5,
The image forming apparatus, wherein the infrared light absorbing toner is transparent toner. The image forming apparatus according to any one of claims 1 to 4 and 6,
The color toner contains a binder resin and a colorant,
The infrared light-absorbing toner contains a binder resin and a near-infrared light-absorbing material, has a 60-degree glossiness of a solid image of 30 or more, and has a 60-degree glossiness of a solid image that is higher than that of the color toner. An image forming apparatus characterized in that the glossiness is 10 or more higher than the 60 degree glossiness of an image. The image forming apparatus according to any one of claims 1 to 4, 6, and 7,
The infrared light-absorbing toner contains a binder resin and a near-infrared light-absorbing material, and has a tangent loss (tan δi) of 2.5 or more within the range of 100° C. or more and 140° C. or less,
The image forming apparatus, wherein the color toner contains a binder resin and a colorant, and has a tangent loss (tan δc) of 2 or less within the range of 100° C. or higher and 140° C. or lower. The image forming apparatus according to any one of claims 1 to 4 and 6 to 8,
The image forming apparatus, wherein the infrared light absorbing toner has a weight average particle size of 5 μm or more and 7 μm or less. The image forming apparatus according to any one of claims 1 to 4 and 6 to 9,
The image forming apparatus, wherein the color toner has an absorbance of less than 0.05 at 800 nm or longer for a solid image. The image forming apparatus according to any one of claims 1 to 4 and 6 to 10,
When a two-dimensional code image made of the infrared light absorbing toner image and a two-dimensional code image made of a solid image of the color toner image are superimposed on each other by the special image forming operation, the color toner 1. An image forming apparatus, wherein the absorbance of a solid image at 800 nm or more and 900 nm or less is less than 0.05. The image forming apparatus according to any one of claims 1 to 11 ,
In the case of the special image forming operation, the control means sets a fixing upper limit value at which the total amount of toner per unit area can be fixed in one fixing process on the toner image composed of the color toner image and the infrared light absorbing toner image. is included, the toner amount is suppressed by performing image processing on the input image information so that the total toner amount of the unfixable portion is equal to or less than the fixing upper limit value. An image forming apparatus characterized by performing control. The image forming apparatus according to claim 12 , wherein
In the image processing, for the unfixable portion, the amount of color toner is made smaller than during the normal image forming operation so that the total toner amount is equal to or less than the upper fixing limit, and for portions other than the unfixable portion, An image forming apparatus, wherein the amount of color toner is kept the same as during the normal image forming operation. The image forming apparatus according to any one of claims 1 to 13 ,
As color conversion data for converting color information of input image information into color information for the image forming apparatus, normal color conversion data used during the normal image forming operation and special color conversion data used when performing the toner amount suppression control are used. a storage means for storing color conversion data;
The control means forms an image from input image information color-converted using the normal color conversion data during the normal image forming operation, and uses the special color conversion data when performing the toner amount suppression control. An image forming apparatus that forms an image from converted input image information. The image forming apparatus according to any one of claims 1 to 14 ,
In the case of the special image forming operation, the control means increases the fixing ability of the fixing means, or makes the fixing processing time of the fixing means longer than that in the normal image forming operation, or An image forming apparatus characterized by performing a fixing condition change control to achieve both. 16. The image forming apparatus according to claim 15 ,
In the case of the special image forming operation, the control means controls the toner image consisting of the color toner image and the infrared light absorbing toner image so that the total amount of toner per unit area is the upper limit of the amount of color toner in the normal image forming operation. The fixing condition change control is performed when it is determined that the excessive toner portion exceeding the value is included, and the fixing condition change control is not performed when it is determined that the excessive toner portion is not included. image forming apparatus . The image forming apparatus according to any one of claims 1 to 16 ,
The image forming apparatus according to claim 1, wherein the infrared light absorbing toner is a toner that forms an image that is difficult to visually recognize on a recording medium .

Images