JP2020112703A - Image forming apparatus and image forming method - Google Patents

Abstract

To provide an image forming apparatus that can prevent continuously-printed printed materials from being electrostatically adhered to each other without reducing productivity during printing, while ensuring heat-resistant storage property and low-temperature fixability of toner.SOLUTION: An image forming apparatus uses a toner containing a binder resin and a photochromic conductive compound in which conductivity is developed by an isomerization reaction by light absorption, and comprises: first light irradiation means that irradiates, with first light, a toner image arranged on a recording medium and formed from the toner; and fixing means that fixes the toner image irradiated with the light.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image forming apparatus and an image forming method.

Conventionally, in an electrophotographic image forming method for forming a visible image by an electrophotographic method, a toner image formed by a toner for electrostatic latent image development (hereinafter, also simply referred to as “toner”) on a transfer medium such as paper is used. As a fixing method, a heat roller fixing method is widely used in which a transfer medium on which a toner image is formed is passed between a heating roller and a pressure roller to fix the transfer medium.

In recent years, from the viewpoint of preventing global warming of the global environment, there is an increasing demand for energy saving in electrophotographic image forming apparatuses. Therefore, in electrophotographic image forming apparatuses employing the heat roller fixing method, A technique for reducing the amount of heat required for fixing a toner image, that is, a technique for lowering the fixing temperature is under study.

On the other hand, in an electrophotographic system, it is possible to transfer a toner image from a photoconductor onto a transfer belt or recording paper by utilizing an electric charge having a polarity opposite to that of the toner. That is, a transfer potential, which is the reverse potential of the toner, is applied from the back side of the object to be transferred and electrically pulled, and at that time, a transfer current is injected onto the transfer belt or the recording paper which is the object of transfer. In general, a material having high electric resistance such as paper or toner is less likely to leak charges as the temperature becomes lower.

For this reason, in the process of low-temperature fixing, the charge accumulated on the paper is less likely to be discharged due to the transfer current, and as a result, the printed image is discharged in a charged state. In this state, when printed materials are continuously stacked, the images stick to each other. As a result of the progress of low-temperature fixing for the purpose of energy saving, it becomes difficult for the charges due to the applied transfer potential to escape, and as a result, the sticking of the printed matter due to the accumulated charges becomes apparent.

As a measure for improving the above problems, a method of spraying negative ions on a fixed image to eliminate static electricity (Patent Document 1), a method of discharging static electricity by alternately discharging static elimination sheets to the fixed image (Patent Document 2), and a plurality of fixed images are eliminated. A method (Patent Document 3) has been proposed in which an intermediate tray provided with a hole is once housed to eliminate static electricity. Patent Document 4 proposes a method in which only a charge eliminating unit corresponding to the plurality of types of electric charges that may be charged on the recording sheet is brought into contact with the recording sheet.

JP, 2006-343491, A JP, 2013-213894, A Japanese Patent Laid-Open No. 11-223964 JP, 2005-281006, A

However, all of the methods described in Patent Documents 1 to 4 described above have a problem in that productivity is reduced during printing because they are methods of removing charge from a fixed image as a post-process. Therefore, there is a demand for means for improving the sticking of the printed matter by improving the toner.

It is generally known that it is effective to lower the thermophysical properties of the binder resin in order to release the charge held by the toner, but it is difficult to achieve both because it has a trade-off relationship with the heat resistant storage property. ..

Therefore, in view of the above problems, the present invention suppresses electrostatic sticking of continuously printed products without reducing productivity during printing while ensuring heat-resistant storage property and low-temperature fixability of toner. It is an object of the present invention to provide an image forming apparatus that can be used.

The present inventors have conducted intensive research. As a result, the photochromic conductive compound whose conductivity is expressed by the isomerization reaction due to light absorption is used for the toner, and the first light is applied to the toner image arranged on the recording medium before fixing. The inventors have found that the above problems can be solved by an image forming apparatus having a first light irradiation means, and have completed the present invention.

That is, the present invention is an image forming apparatus using a toner containing a photochromic conductive compound whose conductivity is expressed by an isomerization reaction due to light absorption, and a binder resin, and a toner image arranged on a recording medium. The image forming apparatus includes: a first light irradiating unit that irradiates a first light to the first image forming unit; and a fixing unit that fixes the light-irradiated toner image.

According to the present invention, by irradiating the toner image arranged on the recording medium with light, the photochromic conductive compound contained in the toner undergoes an isomerization reaction to enhance the conductivity. As a result, the electric charge stored in the toner during fixing can be easily released even when low-temperature fixing is promoted, so that sticking of printed matter can be suppressed without lowering productivity during printing. be able to. Further, it can be compatible with the heat resistant storage property of the toner.

1 is a schematic configuration diagram showing an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a schematic configuration diagram of an irradiation unit in the image forming apparatus. It is a figure explaining the measuring method of sticking force.

The present invention is an image forming apparatus in which a toner containing a photochromic conductive compound whose conductivity is expressed by an isomerization reaction by light absorption and a binder resin are used, and which is formed from the toner arranged on a recording medium. The image forming apparatus includes: a first light irradiating unit that irradiates the formed toner image with the first light; and a fixing unit that fixes the light-irradiated toner image. By using such an image forming apparatus, it is possible to secure the heat-resistant storage property of the toner and the low-temperature fixing property, and at the same time, the printed materials that are continuously printed can be electrostatically stuck to each other without lowering the productivity during printing. Suppressed.

Although the details of the reason why the above-described effects are obtained by the image forming apparatus of the present invention are unknown, it is considered that the following mechanism is used. However, the following mechanism is speculative, and its correctness does not affect the technical scope of the present embodiment.

It has been known that the strength of dielectric breakdown is related to temperature in a resin having a high volume resistance, which is usually used as a binder resin for toner, and usually has a maximum value at a low temperature and decreases as the temperature rises. Therefore, at the time of fixing, if the temperature of the toner becomes higher than the glass transition temperature, the Micro Brownian motion of the main chain of the binder resin becomes active, so that the Young's modulus sharply decreases and the dielectric constant increases, and the dielectric strength sharply decreases. .. Therefore, the charges accumulated in the toner are likely to escape due to the transfer potential.

In an electrophotographic system, the toner is heated to the glass transition temperature or higher during fixing, so if the charge held by the toner during this fixing can be sufficiently leaked, it is possible to paste the printed matter without removing the charge after fixing. It is possible to prevent sticking.

In the present invention, the toner contains a photochromic conductive compound (hereinafter, also referred to as “photochromic conductive compound”) that exhibits conductivity by an isomerization reaction due to light absorption. Then, before fixing, the conductivity of the photochromic conductive compound is enhanced by irradiating the toner image arranged on the recording medium with light. As a result, conductive spots increase on the surface of the binder resin of the melted toner during fixing, which accelerates the leakage of electric charge through water molecules in the air and improves the sticking of printed materials. To be

It is generally known that it is effective to lower the thermophysical properties of the binder resin in order to release the charge held by the toner, but it is difficult to achieve both because it has a trade-off relationship with the heat resistant storage property. .. However, in the present invention, since the conductivity is improved by the light irradiation of the photochromic conductive compound to release the charge retained in the toner, it is possible to solve the problem that the fixed image is stuck without lowering the thermal characteristics of the toner. Becomes Further, it is possible to satisfy both the heat resistant storage property of the toner and the low temperature fixing property.

Hereinafter, an image forming apparatus according to an exemplary embodiment of the present invention will be described. In the present specification, “X to Y” indicating a range means “X or more and Y or less”. In addition, in the present specification, unless otherwise specified, operations and measurements of physical properties are performed under conditions of room temperature (20 to 25° C.)/relative humidity of 40 to 50% RH.

[Image forming device]
FIG. 1 is a schematic configuration diagram showing an image forming apparatus 100 according to an embodiment of the present invention. However, the image forming apparatus of the present invention is not limited to the following modes and illustrated examples. FIG. 1 shows an example of a monochrome image forming apparatus 100, but the present invention can also be applied to a color image forming apparatus.

The image forming apparatus 100 is an apparatus that forms an image on a recording sheet S as a recording medium, and includes an image reading device 71 and an automatic document feeder 72, and an image is formed on the recording sheet S conveyed by a sheet conveying system 7. Image formation is performed by the forming unit 10, the first irradiation unit 40a, the fixing unit (compression bonding unit) 9, and the second irradiation unit 40b. Hereinafter, the first irradiation unit 40a and the second irradiation unit 40b are collectively referred to as the irradiation unit 40.

Although the recording sheet S is used as the recording medium in the image forming apparatus 100, the medium to be subjected to image formation may be other than the sheet.

The document d placed on the document table of the automatic document feeding device 72 is scanned and exposed by the optical system of the scanning exposure device of the image reading device 71 and read into the image sensor CCD. The analog signal photoelectrically converted by the image sensor CCD is subjected to analog processing, A/D conversion, shading correction, image compression processing, etc. in the image processing unit 20, and then input to the exposure unit 3 of the image forming unit 10. It

The paper transport system 7 includes a plurality of trays 16, a plurality of paper feed units 11, a transport roller 12, a transport belt 13, and the like. Each of the trays 16 stores a recording sheet S of a predetermined size, and operates the sheet feeding unit 11 of the tray 16 that is determined according to an instruction from the control unit 90 to supply the recording sheet S. The transport roller 12 transports the recording paper S sent from the tray 16 by the paper feeding unit 11 or the recording paper S carried in from the manual paper feeding unit 15 to the image forming unit 10.

The image forming unit 10 is configured such that a charger 2, an exposure unit 3, a developing unit 4, a transfer unit 5, and a cleaning unit 8 are arranged in this order around the photoconductor 1 along the rotation direction of the photoconductor 1. Has been done.

The photoconductor 1, which is an image carrier, is an image carrier having a photoconductive layer formed on its surface, and is configured to be rotatable in the direction of the arrow in FIG. 1 by a driving device (not shown). A thermo-hygrometer 17 that detects the temperature and humidity inside the image forming apparatus 100 is provided near the photoconductor 1.

The charger 2 evenly charges the surface of the photoconductor 1 to uniformly charge the surface of the photoconductor 1. The exposure device 3 is provided with a beam emission source such as a laser diode, and the surface of the charged photoconductor 1 is irradiated with the beam light so that the electric charge in the irradiated portion is erased and the photoconductor 1 is exposed to light in accordance with image data. Form a latent image. The developing unit 4 supplies the toner accommodated therein to the photoconductor 1 to form a toner image based on the electrostatic latent image on the surface of the photoconductor 1.

The transfer unit 5 faces the photoconductor 1 via the recording sheet S and transfers the toner image onto the recording sheet S. The cleaning unit 8 includes a blade 85. The blade 85 cleans the surface of the photoreceptor 1 to remove the developer remaining on the surface of the photoreceptor 1.

The recording sheet S on which the toner image is formed (transferred) is conveyed to the fixing unit 9 by the conveyor belt 13. The fixing unit 9 is arbitrarily installed, and applies heat and pressure to the recording sheet S on which the toner image is formed (transferred) by the pressure members 91 and 92, thereby performing recording. The image is fixed on the paper S. The recording sheet S on which the image has been fixed is conveyed by the conveying rollers to the sheet discharge unit 14, and discharged from the sheet discharge unit 14 to the outside of the machine.

Further, the image forming apparatus 100 is provided with a sheet reversing unit 24, and the recording sheet S that has been subjected to the heat fixing process is conveyed to the sheet reversing unit 24 before the sheet ejecting unit 14, and the front and back sides are reversed and ejected. Alternatively, it is possible to carry the image on both sides of the recording sheet S again by conveying the recording sheet S with the front and back reversed to the image forming unit 10.

<Irradiator>
FIG. 2 is a schematic configuration diagram of the irradiation unit 40 in the image forming apparatus 100.

The image forming apparatus 100 according to the embodiment of the present invention includes an irradiation unit 40 including a first irradiation unit (first light irradiation unit) 40a and an optional second irradiation unit (second light irradiation unit) 40b. A light emitting diode (LED), a laser light source, etc. are mentioned as an example of the device which comprises the irradiation part 40.

The 1st irradiation part (1st light irradiation means) 40a irradiates with ultraviolet light which has a wavelength in the range of preferably 300 nm or more and less than 400 nm, more preferably 330 nm or more and less than 390 nm. When the wavelength of the first light irradiated by the first light irradiation unit is within the above range, for example, the photochromic conductive compound contained in the developer is reversibly isomerized from the ring-opened body to the ring-closed body by ultraviolet light. In the case of the compound, the isomerization effectively progresses and conductivity is imparted. As a result, the effect of the present invention can be obtained more significantly. Dose of ultraviolet light in the first illumination portion 40a is preferably in the range of 0.1~200J / cm ^2, more preferably in the range of 0.5~100J / cm ^2, more preferably, 1.0 It is within the range of 50 J/cm ² .

It is preferable that the image forming apparatus of the present invention further includes a second light irradiation unit that irradiates the toner image fixed on the recording medium by the fixing unit with the second light. For example, in the case where the photochromic conductive compound is a compound that returns from a ring-closed body to a ring-opened body by visible light, the photochromic conductive compound that is once ring-closed by irradiation with the first light is stored inside the image forming apparatus. It is fixed without exposing to visible light. That is, it is fixed to the ring-opened body without changing. After that, when the fixed image is discharged to the outside of the image forming apparatus, the photochromic conductive compound in the toner spontaneously isomerizes into a ring-opened body by being exposed to visible light. By irradiating visible light as the second light by the light irradiating means, it is possible to rapidly isomerize to a ring-opened product.

In consideration of the light absorption efficiency of the photochromic conductive compound, the second irradiation section (second light irradiation means) 40b preferably has a wavelength within the range of 400 nm to 800 nm, more preferably within the range of 450 nm to 650 nm. Irradiate visible light. The irradiation amount of visible light in the second irradiation section 40b is preferably 0.1 to 200 J/cm ² , more preferably 0.5 to 100 J/cm ² , and still more preferably 0.5 to 50 J/cm ² . ..

The first irradiator 40a and the second irradiator 40b irradiate light toward the first surface of the recording sheet S holding the toner image on the side of the photoconductor, and the photoconductor 1 and the transfer unit (transfer roller) 5 are connected to each other. It is arranged on the photoconductor side with respect to the surface of the recording sheet S nipped at. The first irradiation unit 40a and the second irradiation unit 40b are arranged in this order along the conveyance direction of the recording paper S (paper conveyance direction).

The first irradiation unit 40 a is arranged downstream of the nip position between the photoconductor 1 and the transfer unit 5 in the paper transport direction and upstream of the fixing unit 9 in the paper transport direction.

The second irradiation section 40b is installed downstream of the first irradiation section 40a in the sheet conveyance direction and upstream of the sheet discharge section 14 in the sheet conveyance direction. The second irradiation unit 40b can be installed between the fixing unit 9 and the paper discharge unit 14 in the paper conveyance direction.

According to the image forming method according to the embodiment of the present invention, after the charging device 2 applies a uniform potential to the photoconductor 1 to charge the photoconductor 1, the photoconductor 1 is exposed by the light flux irradiated by the exposure device 3 based on the original image data. The body 1 is scanned to form an electrostatic latent image. Next, the developing section 4 supplies a developer containing a photochromic conductive compound onto the photoreceptor 1.

When the recording sheet S is conveyed from the tray 16 to the image forming unit 10 at the timing when the toner image carried on the surface of the photoconductor 1 arrives at the position of the transfer unit 5 due to the rotation of the photoconductor 1, the recording unit S is transferred to the transfer unit 5. Due to the applied transfer bias, the toner image on the photoconductor 1 is transferred onto the recording sheet S nipped between the transfer unit 5 and the photoconductor 1.

The transfer section 5 also functions as a pressing member, and while transferring the toner image from the photoconductor 1 to the recording sheet S, the optical phase transition compound contained in the toner image can be surely brought into close contact with the recording sheet S. it can.

After the toner image is transferred to the recording sheet S, the blade 85 of the cleaning unit 8 removes the developer remaining on the surface of the photoconductor 1.

In the process in which the recording sheet S on which the toner image has been transferred is conveyed to the fixing unit 9 by the conveyor belt 13, the first irradiation unit 40a detects the toner image transferred on the recording sheet S at 300 nm or more and less than 400 nm. Irradiate ultraviolet light having a wavelength. By irradiating the toner image on the first surface of the recording sheet S with ultraviolet light by the first irradiation section 40a, isomerization of the photochromic conductive compound contained in the toner can be caused. As a result, when the toner image is fixed on the recording sheet S, the charge can be easily leaked from the toner.

When the recording sheet S holding the toner image reaches the fixing unit 9 by the conveyor belt 13, the pressing members (pressurizing means) 91 and 92 press the toner image onto the first surface of the recording sheet S.

The pressing member (pressing means) 91 preferably has a roller shape. Further, the pressing member (pressurizing means) 91 can heat the toner image on the recording sheet S when the recording sheet S passes between the pressing members 91 and 92. The toner image is softened by this heating, and the toner image is fixed on the recording sheet S. The temperature of the pressure member 91 is preferably 120° C. or higher and 200° C. or lower, and more preferably 130° C. or higher and 160° C. or lower.

The recording paper S passing between the pressure members 91 and 92 irradiates the toner image on the recording paper S with visible light having a wavelength of 400 nm or more and 800 nm or less before reaching the paper discharge unit 14. The second irradiation unit 40b is provided. By irradiating visible light from the second irradiating section 40b, the photochromic conductive compound contained in the toner is ring-opened. As a result, the colored ring-closed body in the toner can be rapidly changed to a colorless ring-opened body, and the color stability of the image after output can be improved.

When images are to be formed on both sides of the recording paper S, the recording paper S that has been subjected to the pressure-bonding process is conveyed to the paper reversing unit 24 in front of the paper discharge unit 14 and is reversed and discharged, or the front and back are reversed. The recording sheet S is conveyed again to the image forming unit 10.

By using the image forming apparatus as described above, it is possible to suppress the sticking of the sheets during continuous printing.

Therefore, the image forming method according to a preferred embodiment of the present invention is an image forming method using a toner containing a binder resin and a photochromic conductive compound whose conductivity is expressed by an isomerization reaction due to light absorption. A first light irradiation step of irradiating a toner image formed from the toner arranged on the medium with a first light; and a fixing step of fixing the toner image irradiated with the light. ..

[toner]
The toner used in the image forming apparatus or the image forming method of the present invention contains a photochromic conductive compound that exhibits conductivity by an isomerization reaction due to light absorption, and a binder resin. That is, one embodiment of the present invention is a toner containing a binder resin and a photochromic conductive compound that exhibits conductivity by an isomerization reaction due to light absorption.

Hereinafter, the photochromic conductive compound and the binder resin contained in the toner used in the image forming apparatus or the image forming method of the present invention, and other optional components will be described.

[Photochromic conductive compound]
The photochromic conductive compound used in the toner of the exemplary embodiment is not particularly limited as long as it is a compound that exhibits conductivity by an isomerization reaction due to light absorption, and conventionally known compounds can be used. It is preferable that the isomerization reaction is a compound that reversibly occurs.

Examples of the compound that exhibits conductivity due to the isomerization reaction by light absorption include a compound in which the conjugated system of molecules is expanded by the isomerization by light absorption. Of these, compounds that are photoisomerized between the ring-opened body and the ring-closed body upon irradiation with light are preferable. Examples of the compound that photoisomerizes between the ring-opened compound and the ring-closed compound when irradiated with light include diarylethene compounds, fulgide compounds, spiropyran compounds, and chromene compounds. The ring-closed body of these compounds has conductivity peculiar to a semiconductor due to the spread of the π-conjugated system, and the ring-opened body has insulating properties.

Among them, the photochromic conductive compound is preferably a compound that photoisomerizes from a ring-opened body to a ring-closed body by irradiation with light having a wavelength of 300 nm or more and less than 400 nm. It is necessary to disperse the ring-opened compound of such a compound in the toner so that the toner after transfer is irradiated with ultraviolet light and isomerized to the ring-closed compound while maintaining the charging characteristics required as a developer. The conductive substance is changed to a state in which it is dispersed in the toner, and the charge received from the transfer current is easily released during fixing, which is preferable.

Particularly, the photochromic conductive compound is preferably a diarylethene compound or a fulgide compound. These compounds change from ring-opened to ring-closed by irradiation with ultraviolet light. Therefore, by dispersing these ring-opened compounds in the toner, the toner after transfer can be retained while maintaining the charging characteristics required as a developer. It is preferable that the conductive substance is changed to a state in which it is dispersed in the toner by irradiating it with ultraviolet light to isomerize the ring-closed compound, and the charge received from the transfer current is easily released during fixing. Further, these compounds, after being ring-closed by irradiation with ultraviolet light, are again ring-opened by irradiation with visible light. The diarylethene compound and the fulgide compound show a color when the ring is closed, but they are preferable because they do not interfere with the color characteristics of the image because they open and return to colorless.

Below, the example of the photoisomerization reaction of a diarylethene compound and a fulgide compound is shown. As shown in the following formula, the diarylethene compound photoisomerizes from a ring-opened body to a ring-closed body by irradiation with ultraviolet light, and photoisomerizes from a ring-closed body to a ring-opened body by irradiation with visible light. The ring-closed body has conductivity peculiar to the semiconductor because the π-conjugated system spreads in the molecule, and the ring-opened body does not have conductivity.

Similarly, the fulgide compound also photoisomerizes from a ring-opened body to a ring-closed body by irradiation with ultraviolet light, and photoisomerizes from a ring-closed body to an opened ring by irradiation with visible light. The ring-closed body has conductivity peculiar to the semiconductor because the π-conjugated system spreads in the molecule, and the ring-opened body does not have conductivity.

<Diarylethene compound>
The diarylethene compound is preferably a compound represented by the following chemical formulas (1) to (3).

(In the above chemical formula (1), R ¹ and R ⁴ are each independently an alkyl group, and R ² , R ³ , R ⁵ , and R ⁶ are each independently a hydrogen atom or an alkyl group.)

(In the chemical formula (2), R ¹ and R ⁴ are each independently an alkyl group, R ³ and R ⁶ are each independently a hydrogen atom or an alkyl group, and R ² and R ⁵ are each independently And a hydrogen atom, an alkyl group, or an aryl group.)

(In the above chemical formula (3), R ¹ and R ² are each independently an alkyl group.)
In the chemical formula (1), R ¹ and R ⁴ are each independently an alkyl group, and preferably an alkyl group having 1 to 3 carbon atoms. In particular, it is preferable that R ¹ and R ⁴ are both methyl groups, because photoisomerization from the ring-opened form to the ring-closed form and the accompanying expression of conductivity can be easily obtained.

In the chemical formula (1), R ² , R ³ , R ⁵ , and R ⁶ are each independently a hydrogen atom or an alkyl group, preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. More preferably, each is a methyl group.

In particular, from the viewpoint of production for uniform dispersion in the toner, it is preferable to use a compound in which all R ^{1 to} R ⁶ in the chemical formula (1) are methyl groups.

In the chemical formula (2), R ¹ and R ⁴ are each independently an alkyl group, and preferably an alkyl group having 1 to 3 carbon atoms. In particular, it is preferable that R ¹ and R ⁴ are both methyl groups, because photoisomerization from the ring-opened form to the ring-closed form and the accompanying expression of conductivity can be easily obtained.

In the chemical formula (2), R ³ and R ⁶ are each independently a hydrogen atom or an alkyl group, preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and more preferably both are methyl groups. is there.

In the chemical formula (2), R ² and R ⁵ are each independently a hydrogen atom, an alkyl group, or an aryl group, and preferably a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 6 to 20 carbon atoms. Aryl groups, and even more preferably both are methyl groups.

In particular, from the viewpoint of production for uniform dispersion in the toner, it is preferable to use a compound in which all R ^{1 to} R ⁶ in the chemical formula (2) are methyl groups.

In the chemical formula (3), R ¹ and R ² are each independently an alkyl group, preferably an alkyl group having 1 to 3 carbon atoms. In particular, it is preferable that R ¹ and R ² are both methyl groups, because photoisomerization from a ring-opened form to a ring-closed form and conductivity accompanying the photoisomerization are easily obtained.

<Fulgide compound>
The fulgide compound is not particularly limited, but a compound represented by the following formula (4) is preferably used.

(In the chemical formula (4), each R is independently a hydrogen atom, an alkyl group, an alkoxy group, an aromatic group, or a heteroaromatic group.)
Here, as said alkyl group, a C1-C10 alkyl group is preferable. The alkyl group may be linear or branched.

As the alkoxy group, an alkoxy group having 1 to 10 carbon atoms is preferable. As the aromatic group, an aromatic group having 6 to 20 carbon atoms such as a phenyl group is preferable. As the heteroaromatic group, a heteroaromatic group having 3 to 20 carbon atoms is preferable.

Among them, (E)-2-[1-(2,5-dimethyl-3-furyl)ethylidene]-3-isopropylidene succinic acid represented by the following formula from the viewpoint of production for uniform dispersion in the toner. It is preferable to use an anhydride (fulgide compound (1)).

In addition, the said photochromic conductive compound may be used individually or may be used in combination of 2 or more type.

The content of the photochromic conductive compound is the binder resin contained in the toner, relative to the total amount of the photochromic conductive compound, when a release agent is further contained, the binder resin, the photochromic conductive compound and the release agent The amount is preferably 2 to 20% by mass, more preferably 5 to 10% by mass, based on the total amount. If the content of the photochromic conductive compound is 2% by mass or more with respect to the total amount of the binder resin, the photochromic conductive compound and the release agent (if included), the effect of the present invention can be further obtained. Further, when the content is 20% by mass or less, the photochromic conductive compound can be easily included during the production of the toner. Therefore, the frequency of exposure of the photochromic conductive compound to the surface of the toner is reduced, so that the fluidity is improved and the triboelectric chargeability is excellent. When two or more photochromic conductive compounds are used, the total amount thereof is preferably within the above range.

<Binder resin>
The toner used in the present invention contains a binder resin. As such a binder resin, a resin generally used as a binder resin constituting a toner can be used without limitation. Specific examples thereof include styrene resin, acrylic resin, styrene acrylic resin, polyester resin, silicone resin, olefin resin, amide resin, and epoxy resin. These binder resins may be used alone or in combination of two or more.

Among these, the binder resin is at least one selected from the group consisting of a styrene resin, an acrylic resin, a styrene acrylic resin, and a polyester resin from the viewpoint of having a low viscosity when melted and a high sharp melt property. Is preferable, and it is more preferable to include at least one selected from the group consisting of styrene acrylic resin and polyester resin.

The binder resin preferably used for the toner used in the present invention will be described below.

<<Crystalline polyester resin>>
The toner used in the present invention preferably contains a crystalline polyester resin as a binder resin from the viewpoint of improving low-temperature fixability and heat-storability of the toner.

It has been found that a crystalline resin is effective as a fixing aid in order to achieve both low-temperature fixability of toner and heat-resistant storage stability. Among them, crystalline polyester can obtain sufficient strength even if it is designed to have a low molecular weight by selecting a monomer having an aromatic ring in the molecular main chain, so it is used in combination with an amorphous vinyl resin such as styrene acrylic resin, Even when the Tg design is the same as that of the amorphous vinyl resin, it is possible to reduce the molecular weight, which is advantageous for low-temperature fixability. Further, since it has a large number of polar groups and has a high affinity with paper, the fixability can be improved.

In addition, since the crystalline polyester resin exhibits a sharp decrease in viscosity at the melting point, it becomes possible to achieve further low temperature fixing without lowering the heat resistant storage property. When another binder resin such as an amorphous vinyl resin is used in combination, the crystalline polyester resin is melted and becomes compatible with the other binder resin such as the amorphous vinyl resin in the surrounding area. Since the effect of lowering Tg is also exerted, when heat is applied during fixing, leakage of charges is further accelerated and sticking is also improved.

The "crystalline polyester resin" is a known polyester obtained by a polycondensation reaction of a divalent or higher carboxylic acid (polyvalent carboxylic acid) and its derivative with a divalent or higher valent alcohol (polyhydric alcohol) and its derivative. Among the resins, it refers to a resin having a clear endothermic peak instead of a stepwise endothermic change in differential scanning calorimetry (DSC). The clear endothermic peak specifically means that the half-value width of the endothermic peak is 15° C. or less when measured at a temperature rising rate of 10° C./min in differential scanning calorimetry (DSC) described in the following examples. It means a certain peak.

The differential scanning calorimetry (DSC) can be measured using, for example, a differential scanning calorimeter "Diamond DSC" (manufactured by Perkin Elmer). The measurement is the first temperature rising process in which the temperature is raised from room temperature (25° C.) to 150° C. at a raising/lowering rate of 10° C./min, and is isothermally held at 150° C. for 5 minutes. Cooling process, in which the temperature is kept constant at 0° C. for 5 minutes, and a second temperature rising process in which the temperature is raised from 0° C. to 150° C. at a lifting speed of 10° C./min. ). The above measurement is performed by enclosing 3.0 mg of a sample in an aluminum pan and setting it in a sample holder of a differential scanning calorimeter "Diamond DSC". Use an empty aluminum pan as a reference.

In the above measurement, analysis is performed from the endothermic curve obtained in the first temperature rising process, and the top temperature of the endothermic peak derived from the crystalline polyester resin is taken as the melting point of the crystalline polyester resin.

Examples of polyvalent carboxylic acid derivatives include alkyl esters of polyvalent carboxylic acids, acid anhydrides and acid chlorides, and examples of polyhydric alcohol derivatives include ester compounds of polyhydric alcohols and hydroxycarboxylic acids.

The polycarboxylic acid is a compound containing two or more carboxyl groups in one molecule. Among these, a divalent carboxylic acid is a compound containing two carboxyl groups in one molecule, and examples thereof include oxalic acid, malonic acid, succinic acid, adipic acid, pimelic acid, sebacic acid, azelaic acid and n-dodecyl. Succinic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid (dodecanedioic acid), 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid (tetradecanedioic acid), 1,13-tri Saturated aliphatic dicarboxylic acids such as decanedicarboxylic acid and 1,14-tetradecanedicarboxylic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; unsaturated aliphatic dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid and itaconic acid; Examples thereof include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid. Examples of the polyvalent carboxylic acid other than the divalent carboxylic acid include trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid. Examples of the polycarboxylic acid derivative include anhydrides of these carboxylic acid compounds and alkyl esters having 1 to 3 carbon atoms. These may be used alone or in combination of two or more.

Polyhydric alcohol is a compound containing two or more hydroxyl groups in one molecule. Among them, the divalent polyol (diol) is a compound containing two hydroxy groups in one molecule, and examples thereof include ethylene glycol, 1,2-propanediol, 1,3-propanediol and 1,4-butane. Diol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12- Aliphatic diols such as dodecanediol, neopentyl glycol and 1,4-butenediol can be mentioned. Examples of the polyol other than the divalent polyol include trihydric or higher polyhydric alcohols such as glycerin, pentaerythritol, trimethylolpropane, and sorbitol. These may be used alone or in combination of two or more.

In addition, depending on the valency of the polyhydric carboxylic acid and the valency of the polyhydric alcohol, it may have some branching or crosslinking.

The method for forming the crystalline polyester resin using the above monomer is not particularly limited, and by polycondensing (esterifying) the above polyvalent carboxylic acid and polyhydric alcohol using a known esterification catalyst. The resin can be formed. Examples of the esterification catalyst that can be used include titanium acetate, titanium propionate, titanium hexanoate, titanium monocarboxylic acid such as titanium octanoate, titanium oxalate, titanium succinate, titanium maleate, titanium adipate, and sebacic acid. Aliphatic carboxylates such as titanium aliphatic dicarboxylates such as titanium, titanium hexanetricarboxylate, titanium titanium tricarboxylates such as isooctane tricarboxylic acid, titanium octane tetracarboxylates, titanium titanium polycarboxylates such as titanium decane tetracarboxylates, etc. Aromatic titanium monocarboxylic acid such as titanium acid and titanium benzoate, titanium phthalate, titanium terephthalate, titanium isophthalate, titanium naphthalene dicarboxylate, titanium biphenyldicarboxylate, titanium anthracene dicarboxylate and the like; Aromatic titanium carboxylates such as titanium trimellitate and titanium naphthalene tricarboxylate; titanium aromatic tetracarboxylates such as titanium benzene tetracarboxylate and titanium naphthalene tetracarboxylate; titanium aromatics such as and aliphatic carboxylic acids Titanium compounds of titanium and aromatic titanium carboxylates and their alkali metal salts, titanium halides such as dichlorotitanium, trichlorotitanium, tetrachlorotitanium and tetrabromotitanium, tetrabutoxytitanium (titanium tetrabutoxide), tetra Examples thereof include titanium-containing catalysts such as tetraalkoxytitaniums such as octoxytitanium and tetrastearyloxytitanium, titanium acetylacetonate, titanium diisopropoxide bisacetylacetonate, and titanium triethanolaminate.

The melting point (Tm) of the crystalline polyester resin is preferably in the range of 50 to 90°C, and more preferably in the range of 60 to 80°C from the viewpoint of obtaining sufficient low temperature fixing property and heat resistant storage property. preferable. As the melting point (Tm) of the crystalline polyester resin, the value measured by the method described in Examples is adopted.

The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 5,000 to 50,000, and more preferably 5,000 to 30,000 from the viewpoint of low-temperature fixability and gloss stability. preferable.

The content of the crystalline polyester resin is based on the total amount of the binder resin, the photochromic conductive compound, and the release agent (when included) contained in the toner, from the viewpoint of obtaining sufficient low-temperature fixing property and heat-resistant storage property. Is preferably 5 to 20% by mass, more preferably 5 to 15% by mass, and further preferably 7 to 15% by mass. When the content of the crystalline polyester resin is 5% by mass or more with respect to the total amount (total mass) of the binder resin, the photochromic conductive compound, and the release agent (when included), the low temperature fixability is excellent. On the other hand, when the content is 20% by mass or less, the crystalline polyester resin is included in the toner particles in a state of being uniformly dispersed during the production, so that sufficient fluidity is obtained and the triboelectric charging property is excellent. In addition, since the crystalline polyester resin is uniformly dispersed in the toner particles, crystallization can be suppressed and thus storage stability is excellent.

<<Amorphous resin>>
In the present specification, the amorphous resin refers to a resin that does not have a melting point and has a relatively high glass transition temperature (Tg) when performing differential scanning calorimetry (DSC). At this time, the glass transition temperature (Tg) is preferably 30 to 80°C, and particularly preferably 40 to 65°C. The glass transition temperature (Tg) can be measured by a differential calorimeter (DSC),
The weight average molecular weight (Mw) of the amorphous resin is not particularly limited, but is preferably 2,000 to 150,000, more preferably 10,000 to 100,000.

As the amorphous resin, a conventionally known amorphous resin in the present technical field can be used, but among them, an amorphous polyester resin or an amorphous vinyl resin is preferable, and a mixture of these resins is used. Good. Among them, the amorphous resin preferably contains an amorphous vinyl resin, preferably contains a styrene resin, and contains a styrene acrylic resin, from the viewpoint of being excellent in environmental stability of the charge amount. Is more preferable.

Preferred examples of the amorphous resin other than the styrene acrylic resin include an amorphous polyester resin and a hybrid amorphous polyester resin. These amorphous resins can be obtained by known synthetic methods or commercially available. Further, when the toner base particles have a core-shell structure, it is more preferable that the styrene acrylic resin and the crystalline polyester resin constitute the core particles, and the amorphous polyester resin or the hybrid amorphous polyester resin constitutes the shell part. More preferably, the styrene acrylic resin and the crystalline polyester resin constitute the core particles, and the hybrid amorphous polyester resin constitutes the shell portion. By doing so, the crystalline polyester resin is well dispersed in the toner particles, so that the low-temperature fixability is excellent. In addition, the charging characteristics of the toner can be improved.

(Styrene acrylic resin)
The styrene-acrylic resin in the present invention is formed by polymerizing at least a styrene monomer and a (meth)acrylic acid ester monomer. Here, the styrene monomer includes not only styrene represented by the structural formula of CH ₂ ═CH—C ₆ H ₅ but also those having a known side chain or functional group in the styrene structure.

Further, the (meth)acrylic acid ester monomer has a functional group having an ester bond in the side chain. _{Specifically,} CH 2 = CHCOOR (R is an alkyl group) other acrylic acid ester monomer represented _by, methacrylic acid ester represented by _{CH 2 = C (CH 3)} COOR (R is an alkyl group) A vinyl ester compound such as a monomer is included.

Specific examples of the styrene monomer and the (meth)acrylic acid ester monomer capable of forming the styrene acrylic resin are shown below, but the present invention is not limited to those shown below.

Examples of the styrene monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene and p-. Examples thereof include t-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene and pn-dodecyl styrene.

Further, the (meth)acrylic acid ester monomer is typically the acrylic acid ester monomer and the methacrylic acid ester monomer shown below, and examples of the acrylic acid ester monomer include methyl acrylate and Examples thereof include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, dodecyl acrylate and phenyl acrylate phenyl. Examples of the methacrylic acid ester monomer include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate. , Dodecyl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate and the like.

These styrene monomers, acrylic acid ester monomers, or methacrylic acid ester monomers can be used alone or in combination of two or more.

Further, the styrene-acrylic copolymer includes, in addition to the above-mentioned copolymer formed only of the styrene monomer and the (meth)acrylic acid ester monomer, the styrene monomer and the (meth)acrylic acid ester. In addition to the monomer, some are formed by using a general vinyl monomer together. The vinyl monomers that can be used together when forming the styrene-acrylic copolymer according to the present invention are illustrated below, but the vinyl monomers that can be used together are not limited to those shown below.

(1) Olefins, ethylene, propylene, isobutylene, etc. (2) Vinyl esters, vinyl propionate, vinyl acetate, vinyl benzoate, etc. (3) Vinyl ethers, vinyl methyl ether, vinyl ethyl ether, etc. (4) Vinyl ketones, vinyl methyl ketone, Vinyl ethyl ketone, vinyl hexyl ketone, etc. (5) N-vinyl compounds N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, etc. (6) Other vinyl compounds such as vinyl naphthalene, vinyl pyridine, acrylonitrile, methacryloyl Acrylic acid or methacrylic acid derivatives such as nitrile and acrylamide.

It is also possible to prepare a resin having a crosslinked structure by using a polyfunctional vinyl monomer. Furthermore, it is also possible to use a vinyl monomer having an ionic dissociative group in the side chain. Specific examples of the ionic dissociative group include a carboxyl group, a sulfonic acid group, and a phosphoric acid group. Specific examples of vinyl monomers having these ionic dissociative groups are shown below.

Specific examples of the vinyl monomer having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, and itaconic acid monoalkyl ester. ..

The method for forming the styrene acrylic resin is not particularly limited, and examples thereof include a method of polymerizing a monomer using a known oil-soluble or water-soluble polymerization initiator. A known chain transfer agent may be used if necessary.

When forming the styrene acrylic resin used in the present invention, the contents of the styrene monomer and the acrylate monomer are not particularly limited, and control the softening point and glass transition temperature of the binder resin. It can be appropriately adjusted from the viewpoint. Specifically, the content of the styrene monomer is preferably 40 to 95% by mass, and more preferably 50 to 80% by mass, based on the whole monomer. The content of the acrylic acid ester monomer is preferably 5 to 60% by mass, and more preferably 10 to 50% by mass, based on the total amount of the monomers.

The method for forming the styrene acrylic resin is not particularly limited, and examples thereof include a method of polymerizing a monomer using a known oil-soluble or water-soluble polymerization initiator. Specific examples of the oil-soluble polymerization initiator include azo-based or diazo-based polymerization initiators and peroxide-based polymerization initiators shown below.

Examples of the azo or diazo polymerization initiator include 2,2′-azobis-(2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile and 1,1′-azobis(cyclohexane-1). -Carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile and the like.

As the peroxide-based polymerization initiator, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2, 4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-(4,4-t-butylperoxycyclohexyl)propane, tris-(t-butylperoxy)triazine and the like can be mentioned.

Further, when the styrene acrylic resin particles are formed by the emulsion polymerization method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble radical polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropaneacetic acid salts, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

The polymerization temperature varies depending on the type of monomer and the polymerization initiator used, but is preferably 50 to 100°C, more preferably 55 to 90°C. Further, the polymerization time varies depending on the type of the monomer and the polymerization initiator used, but is preferably 2 to 12 hours, for example.

The styrene-acrylic resin particles formed by the emulsion polymerization method may be composed of two or more layers made of resins having different compositions. In this case, the production method is as follows: a dispersion of resin particles prepared by an emulsion polymerization treatment (first-stage polymerization) according to a conventional method, a polymerization initiator, a polymerizable monomer, and optionally a release agent. Can be added, and a multistage polymerization method in which this system is subjected to a polymerization treatment (second stage polymerization, third stage polymerization) can be adopted.

<Hybrid amorphous polyester resin>
In the toner according to one embodiment of the present invention, the amorphous resin is a hybrid amorphous polyester resin in which an amorphous polyester polymer segment and a vinyl polymer segment having a styrene-derived constitutional unit are chemically bonded. It is preferable to contain More specifically, the amorphous resin is a hybrid amorphous polyester resin having a graft copolymer structure in which an amorphous polyester polymer segment and a vinyl polymer segment having a structural unit derived from styrene are chemically bonded. Is preferably contained in the shell portion of the toner having a core-shell structure. In particular, by preparing a toner having a core-shell structure in which an amorphous vinyl resin is used as a core particle and including such a hybrid amorphous polyester resin in the shell part, the compatibility between the core particle and the shell part is improved. While maintaining the above, the affinity for the amorphous vinyl resin is moderately increased. Therefore, the shell portion is more easily attached to the core particles, and the heat-resistant storage stability of the toner is further improved.

The amorphous polyester polymerized segment is a portion derived from a polyester resin obtained by a polycondensation reaction with a polyvalent carboxylic acid component and a polyhydric alcohol component, and has a clear endotherm in differential scanning calorimetry (DSC) of the toner. A polymerized segment in which no peak is observed.

Examples of the polyvalent carboxylic acid component include oxalic acid, succinic acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid. , Fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydroterephthalic acid, malonic acid, pimelic acid, tartaric acid, mucus acid, phthalic acid , Isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylenediacetic acid, m-phenylenediglycolic acid, p-phenylenediglycolic acid, o-phenylenediglycolic acid , Diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracene dicarboxylic acid, dodecenylsuccinic acid Acid; trimellitic acid, pyromellitic acid and the like can be mentioned. These polycarboxylic acids can be used alone or in admixture of two or more. Among these, it is preferable to use aliphatic unsaturated dicarboxylic acids such as fumaric acid, maleic acid and mesaconic acid, aromatic dicarboxylic acids such as isophthalic acid and terephthalic acid, succinic acid and trimellitic acid.

Examples of the polyhydric alcohol component include ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, octanediol, decanediol, dodecanediol, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct. And dihydric alcohols such as glycerin, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, and tetrahydric polyols such as tetraethylolbenzoguanamine. These polyhydric alcohol components may be used alone or in admixture of two or more. Among these, dihydric alcohols such as bisphenol A ethylene oxide adducts and bisphenol A propylene oxide adducts are preferable.

The amorphous polyester polymerized segment is not particularly limited as long as it is as defined above. For example, regarding a resin having a structure in which the main chain of the amorphous polyester polymerized segment is copolymerized with another component, or a resin having a structure in which the amorphous polyester polymerized segment is copolymerized with the main chain of the other component, If the toner containing the resin does not have a clear endothermic peak as described above, the resin corresponds to the hybrid amorphous polyester resin having the amorphous polyester polymerized segment in the present invention.

The content of the amorphous polyester polymerized segment is preferably 75 to 98 mass% with respect to the total amount of the hybrid amorphous polyester resin. The constituent components and the content ratio of each segment in the hybrid amorphous polyester resin can be specified by, for example, NMR measurement and methylation reaction Py-GC/MS measurement.

The hybrid amorphous polyester resin contains, in addition to the amorphous polyester polymerized segment, a vinyl polymerized segment containing a styrene-derived constitutional unit. The vinyl polymer segment is not particularly limited as long as it contains a structural unit derived from styrene, but a styrene-(meth)acrylic acid ester polymer segment (styrene acrylic polymer segment) is preferable in consideration of plasticity at the time of heat fixing.

The styrene acrylic polymer segment is formed by addition-polymerizing at least a styrene monomer and a (meth)acrylic acid ester monomer. Specific examples of the monomer capable of forming the styrene acrylic polymer segment include the same monomers as those described above for the styrene acrylic resin.

The content of the styrene-derived constitutional unit in the vinyl polymerized segment is preferably 40 to 95 mass% with respect to the total amount of the vinyl polymerized segment. The content of the structural unit derived from the (meth)acrylic acid ester monomer in the vinyl polymerized segment is preferably 5 to 60% by mass with respect to the total amount of the vinyl polymerized segment.

Further, the vinyl polymerized segment is preferably formed by addition-polymerizing a compound for chemically bonding to the amorphous polyester polymerized segment in addition to the styrene monomer and the (meth)acrylic acid ester monomer. Specifically, it is preferable to use a compound which is contained in the crystalline polyester polymerized segment and forms an ester bond with a hydroxyl group [-OH] derived from a polyhydric alcohol component or a carboxyl group [-COOH] derived from a polyvalent carboxylic acid component. .. Therefore, the vinyl polymerization segment is addition-polymerizable with styrene and the (meth)acrylic acid ester monomer, and is further polymerized with a compound having a carboxyl group [-COOH] or a hydroxyl group [-OH]. Is preferred.

Examples of such compounds include compounds having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester; 2-hydroxy. Ethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate And a compound having a hydroxyl group such as polyethylene glycol mono(meth)acrylate.

The content of the structural unit derived from the above compound in the vinyl polymerized segment is preferably 0.5 to 20 mass% with respect to the total amount of the vinyl polymerized segment.

The method for forming the styrene acrylic polymer segment is not particularly limited, and examples thereof include a method of polymerizing a monomer using a known oil-soluble or water-soluble polymerization initiator. Specific examples of the polymerization initiator are the same as those described in the section of the styrene acrylic resin.

The content of the vinyl polymerized segment is preferably 2 to 25% by mass in the hybrid amorphous polyester resin.

As a method for producing the hybrid amorphous polyester resin, an existing general scheme can be used. The following three are typical methods.

(1) A method for producing a hybrid amorphous polyester resin by preliminarily polymerizing a vinyl polymerized segment and carrying out a polymerization reaction to form an amorphous polyester polymerized segment in the presence of the vinyl polymerized segment (2) Amorphous A method for producing a hybrid amorphous polyester resin by forming a non-crystalline polyester polymer segment and a vinyl polymer segment, respectively, and combining them (3) The non-crystalline polyester polymer segment is preliminarily polymerized A method for producing a hybrid amorphous polyester resin by carrying out a polymerization reaction to form a vinyl polymerized segment in the presence of a polyester polymerized segment.

The toner used in the present invention may contain other components such as a colorant, a release agent, a charge control agent, and an external additive in addition to the photochromic conductive compound and the binder resin. Hereinafter, other components will be described.

<Colorant>
The toner of the present invention may contain a colorant. As the colorant, generally known dyes and pigments can be used.

Examples of the colorant for obtaining a black toner include carbon black, magnetic materials, iron-titanium composite oxide black, and the like.Examples of carbon black include channel black, furnace black, acetylene black, thermal black, and lamp black. Can be mentioned. Further, examples of the magnetic material include ferrite and magnetite.

As a colorant for obtaining a yellow toner, C.I. I. Solvent Yellow 19, dye 44, dye 77, dye 79, dye 81, dye 82, dye 93, dye 98, dye 103, dye 104, dye 112, dye 162; I. Pigment Yellow 14, the same 17, the same 74, the same 93, the same 94, the same 138, the same 155, the same 180, the same 185 and the like.

As the colorant for obtaining the magenta toner, C.I. I. Dyes such as Solvent Red 1, 49, 52, 58, 63, 111 and 122; C.I. I. Pigment Red 5, pigments 48:1, 53:1, 57:1, 122, 139, 144, 149, 166, 177, 178, 222 and the like.

As the colorant for obtaining the cyan toner, C.I. I. Solvent Blue 25, Dye 36, Dye 60, Dye 70, Dye 93, Dye 95, etc.; C.I. I. Pigment Blue 1, the same 7, the same 15, the same 15:2, the same 15:3, the same 15:4, the same 16, the same 60, the same 62, the same 66, the same 76 and the like.

The colorant for obtaining the toner of each color can be used alone or in combination of two or more for each color.

The size of the colorant (particles) is not particularly limited, but the volume-based median diameter is preferably 10 to 1000 nm, more preferably 50 to 500 nm, and particularly preferably 80 to 300 nm. .. Within such a range, high color reproducibility can be obtained, and it is preferable in that it is suitable for forming a small-diameter toner required for high image quality. The volume-based median diameter of the colorant (particles) can be measured using, for example, Microtrac (registered trademark, the same applies hereinafter) particle size distribution measuring device “UPA-150” (manufactured by Nikkiso Co., Ltd.).

The content of the colorant in the toner is preferably 0.5 to 20% by mass, more preferably 2 to 10% by mass.

<Release agent>
The toner used in the present invention may contain a release agent. The release agent used is not particularly limited, and various known waxes can be used. For example, polyethylene wax, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, dialkyl ketone wax such as distearyl ketone, carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetramyristate, pentaerythritol. Tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitate, distearyl maleate, behenyl behenate And ester waxes such as ethylenediamine dibehenylamide, and amide waxes such as trimellitic acid tristearylamide.

The content of the release agent in the toner is preferably in the range of 2 to 30% by mass, more preferably 5 to 20% by mass.

<Charge control agent>
The toner according to the present invention may contain a charge control agent. The charge control agent used is not particularly limited as long as it is a substance capable of imparting positive or negative charge by triboelectric charging and is colorless, and various known positive charge control agents and negative charge control agents can be used. An electrostatic charge control agent can be used.

The content ratio of the charge control agent in the toner is preferably 0.01 to 30% by mass, more preferably 0.1 to 10% by mass.

<External additive>
In order to improve the fluidity, charging property, cleaning property, etc. of the toner, an external additive such as a so-called post-treatment agent, a fluidizing agent or a cleaning aid is added to the toner particles to form an image forming apparatus of the present invention. It may constitute a toner that can be used.

As the external additive, for example, silica particles, alumina particles, inorganic oxide particles such as titanium oxide particles, aluminum stearate particles, inorganic stearic acid compound particles such as zinc stearate particles, strontium titanate particles, zinc titanate particles. Inorganic particles such as inorganic titanate compound particles. If necessary, these inorganic particles may be subjected to a hydrophobizing treatment. These can be used alone or in combination of two or more.

Among these, as the external additive, for example, sol-gel silica particles, silica particles whose surface is hydrophobized (hydrophobic silica particles) or titanium oxide particles (hydrophobic titanium oxide particles) are preferable, and at least these It is more preferable to use two or more external additives.

The number average primary particle diameter of the external additive is preferably in the range of 1 to 200 nm, more preferably 10 to 180 nm. At this time, it is particularly preferable that at least one of the external additives has a thickness of 30 nm or more and 180 nm or less.

The addition amount of these external additives is preferably 0.05 to 5% by mass in the toner, and more preferably 0.1 to 3% by mass.

<Average particle size of toner>
The average particle diameter of the toner is preferably 3 to 9 μm in terms of volume-based median diameter (D50), and more preferably 3 to 8 μm. When the volume-based median diameter (D50) is within the above range, the transfer efficiency is increased, the halftone image quality is improved, and the image quality of fine lines and dots is improved.

In the present invention, the volume-based median diameter (D50) of the toner is a computer system (Beckman Coulter) in which "Coulter Counter 3" (manufactured by Beckman Coulter, Inc.) is equipped with data processing software "Software V3.51". It is measured and calculated using a measuring device connected to a product manufactured by Co., Ltd.

Specifically, 0.02 g of a measurement sample (toner) was used as a surfactant solution 20 mL (for the purpose of dispersing toner particles, for example, a neutral detergent containing a surfactant component was diluted 10 times with pure water. (Solution) and acclimated to it, ultrasonic dispersion is carried out for 1 minute to prepare a toner dispersion, and this toner dispersion is put in "ISOTONII" (manufactured by Beckman Coulter, Inc.) in a sample stand. Pipette into the beaker until the indicated concentration on the measuring device is 8%.

Here, by setting this concentration range, reproducible measurement values can be obtained. Then, in the measuring device, the number of particles to be measured was set to 25,000, the aperture diameter was set to 50 μm, and the frequency value was calculated by dividing the range of 1 to 30 μm, which is the measurement range, into 256. The particle diameter of% is the volume-based median diameter (D50).

[Toner manufacturing method]
The method for producing the toner used in the present invention is not particularly limited, but a production method utilizing an emulsion aggregation method in which the particle size and shape can be easily controlled is preferable.

The emulsion aggregation method is a dispersion of binder resin particles (hereinafter, also referred to as "binder resin particles") dispersed by a surfactant or a dispersion stabilizer, and optionally a release agent particle (hereinafter, " (Also referred to as “releasing agent particles”) and a colorant particle, and the particles are aggregated until a desired particle size is obtained, and the shape of the toner is controlled by fusing the binder resin particles together. This is a method for producing particles.

The procedure for introducing the photochromic conductive compound is also not particularly limited, and for example, a dispersion of particles of the photochromic conductive compound is prepared, mixed with a dispersion of release agent particles or particles of a colorant, or separately from this. Alternatively, they may be aggregated and fused by mixing with a dispersion liquid of binder resin particles. At this time, when preparing the dispersion liquid of the particles of the photochromic conductive compound, it is prepared by the procedure according to the method for preparing the colorant particle dispersion liquid described in (a-4) Preparation step of the colorant particle dispersion liquid described later. can do.

Alternatively, for example, as described in (a-1) Styrene acrylic resin particle dispersion liquid preparation step described below, at the stage of preparing a dispersion liquid of binder resin particles, a photochromic conductive compound is added to the binder resin (or a single resin thereof). The binder resin particles containing the photochromic conductive compound can be obtained by adding the binder resin particles to the aqueous medium containing the monomer. At this time, the photochromic conductive compound may be added to the above aqueous medium in the form of powder (particulate) or, if necessary, dissolved in an organic solvent. When a plurality of binder resin particle dispersions are prepared, any binder resin particles may contain a photochromic conductive compound.

Further, toner particles having a core-shell structure can also be obtained by an emulsion aggregation method. Specifically, the toner particles having a core-shell structure first aggregate the binder resin particles for the core particles and the colorant particles (, (Fusion) to produce core particles, and then the binder resin particles for the shell portion are added to the dispersion liquid of the core particles to aggregate and fuse the binder resin particles for the shell portion to the surface of the core particles. It can be obtained by forming a shell portion that covers the surface of the core particle.

Hereinafter, by the emulsion aggregation method, as a core particle, a styrene acrylic resin and a crystalline polyester resin that is a binder resin, a colorant, a release agent, and a photochromic conductive compound, a hybrid amorphous as a shell portion. An example of producing a toner having a core-shell structure having a hydrophilic polyester resin will be specifically described.

A method for producing a toner according to a preferred embodiment is a step of preparing a crystalline polyester resin particle dispersion, a styrene acrylic resin particle dispersion, and a hybrid amorphous polyester resin particle dispersion (hereinafter, also referred to as a preparation step) (a). And a step of mixing the crystalline polyester resin particle dispersion liquid and the styrene-acrylic resin particle dispersion liquid and aggregating and fusing them to obtain a core particle dispersion liquid (hereinafter, also referred to as aggregating and fusing step) (b). A step (c) of mixing the core particle dispersion and the hybrid amorphous polyester resin particle dispersion and aggregating and fusing them to obtain a toner particle dispersion.

Hereinafter, each step (a) to (c) and each step (d) to (f) optionally performed in addition to these steps will be described in detail, but the method is not limited to the following method.

(A) Preparation Step In the step (a), there is a step of preparing a crystalline polyester resin particle dispersion liquid, a styrene acrylic resin particle dispersion liquid, and optionally a hybrid amorphous polyester resin particle dispersion liquid, and if necessary, And a colorant dispersion liquid preparation step and the like.

(A-1) Styrene acrylic resin particle dispersion liquid preparation step For the styrene acrylic resin particle dispersion liquid, for example, a method of performing dispersion treatment in an aqueous medium without using a solvent, or dissolving the styrene acrylic resin in a solvent such as ethyl acetate The solution may be used as a solution, and the solution may be emulsified and dispersed in an aqueous medium using a disperser, and then a solvent removal treatment may be performed. Preferably, a styrene acrylic resin is dispersed in an aqueous medium to prepare a styrene acrylic resin particle dispersion liquid.

The aqueous medium refers to a medium having a water content of 50% by mass or more, and contains water or an organic solvent, a surfactant, a dispersant, and other optional components that are soluble in water as a main component. Examples include aqueous media. Examples of the organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, tetrahydrofuran and the like. Of these, alcohol-based organic solvents such as methanol, ethanol, isopropanol, butanol, which are organic solvents that do not dissolve the resin, are preferable. As the aqueous medium, a mixture of water and a surfactant is preferably used.

Examples of the surfactant include cationic surfactants, anionic surfactants, nonionic surfactants and the like. Examples of the cationic surfactant include dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, hexadecyl trimethyl ammonium bromide and the like. Examples of the anionic surfactant include fatty acid soaps such as sodium stearate and sodium dodecanoate, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate. Examples of nonionic surfactants include polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecyl ether, polyoxyethylene sorbitan monooleate ether, and monodecanoyl. Examples include sucrose.

Such surfactants can be used alone or in combination of two or more. Among the surfactants, preferably anionic surfactants, more preferably sodium dodecylbenzene sulfonate are used.

The addition amount of the surfactant is preferably 0.01 parts by mass or more and 10 parts by mass or less, more preferably 0.04 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the aqueous medium.

The dispersion treatment is preferably carried out under stirring, and can be carried out by utilizing mechanical energy, and the disperser is not particularly limited, and includes a homogenizer, a low-speed shearing disperser, and a high-speed shearing disperser. Examples thereof include a disperser, a friction disperser, a high-pressure jet disperser, an ultrasonic disperser, a high-pressure impact disperser Ultimizer, and an emulsifying disperser.

The method for producing the styrene acrylic resin is not particularly limited, and a known oil-soluble or water-soluble polymerization initiator is used, and the bulk polymerization method, solution polymerization method, emulsion polymerization method, miniemulsion method, dispersion polymerization method, etc. are known. The method of carrying out the polymerization by the above-mentioned polymerization method can be mentioned. If necessary, a known chain transfer agent such as n-octyl mercaptan may be used. Above all, it is preferable to use an emulsion polymerization method in which a resin monomer is added to an aqueous medium together with a polymerization initiator, and the monomer is subjected to a polymerization reaction to obtain a dispersion liquid of resin particles.

In the emulsion polymerization method, the following seed polymerization is preferable. Specifically, a monomer for obtaining a styrene acrylic resin (styrene monomer, (meth)acrylic acid ester monomer, etc.) is added together with a polymerization initiator into an aqueous medium and polymerized to form basic particles. obtain. Next, in the dispersion liquid in which the resin particles are dispersed, a radical polymerizable monomer for obtaining a styrene acrylic resin and a polymerization initiator are added, and the radical polymerizable monomer is seed-polymerized to the basic particles. It is preferable to use the method.

Further, for example, in the case of carrying out the polymerization reaction in three stages, a dispersion liquid of resin particles is prepared by the first stage polymerization, and a monomer of the resin and a polymerization initiator are further added to this dispersion liquid to carry out the second stage polymerization. Let A resin monomer and a polymerization initiator are further added to the dispersion liquid prepared by the second stage polymerization to carry out the third stage polymerization. During the second and third stages of polymerization, the resin particles in the dispersion liquid produced by the previous polymerization can be used as seeds to further polymerize the monomer newly added to the resin particles, It is possible to make the particle size of the resin particles uniform. In addition, by using different monomers in the polymerization reaction at each stage, the structure of the resin particles can be a multi-layered structure, and resin particles having desired characteristics can be easily obtained.

Although not particularly limited, it is preferable to add a photochromic conductive compound at this stage. Further, at this stage, a release agent may be contained. In this case, in order to improve the dispersibility of the photochromic conductive compound and the release agent, mechanical energy was added after adding the photochromic conductive compound, the release agent and the polymerizable monomer (mixture) to the aqueous medium. It is preferable to add and stir, and a homogenizer, a low speed shearing disperser, a high speed shearing disperser, a friction disperser, a high pressure jet disperser, an ultrasonic disperser, a high pressure impact disperser, an ultimizer, and the like dispersion. It is preferable to use a machine. A commercially available product may be used as the disperser, and for example, "CLEARMIX (registered trademark)" (manufactured by M Technique), HJP30006 (manufactured by Sugino Machine Co., Ltd.), ultrasonic homogenizer US-150T (Japan). Seiki Seisakusho) and the like can be used.

During dispersion, it is preferable to heat the solution. The heating condition is not particularly limited, but is usually about 60 to 100°C.

(Polymerization initiator)
As the polymerization initiator that can be used in the polymerization reaction, known ones can be used, and examples thereof include persulfates such as ammonium persulfate, sodium persulfate, potassium persulfate, and 2,2′-azobis(2-aminodipropane). ) Hydrochloride, 2,2'-azobis-(2-aminodipropane) nitrate, 4,7'-azobis-4-cyanovaleric acid, poly(tetraethylene glycol-2,2'-azobisisobutyrate) Examples thereof include azo compounds such as, and peroxides such as hydrogen peroxide.

The addition amount of the polymerization initiator varies depending on the target molecular weight and the molecular weight distribution, but is specifically within the range of 0.1 to 5.0 mass% with respect to the addition amount of the polymerizable monomer. it can.

(Chain transfer agent)
During the polymerization reaction, a chain transfer agent can be added from the viewpoint of controlling the molecular weight of the resin particles. Examples of chain transfer agents that can be used include mercaptans such as octyl mercaptan, dodecyl mercaptan, and t-dodecyl mercaptan; chain transfer agents such as n-octyl-3-mercaptopropionate and stearyl-3-mercaptopropionate. Mercaptopropionic acid; and styrene dimer can be used. These can be used alone or in combination of two or more.

The addition amount of the chain transfer agent varies depending on the target molecular weight and the molecular weight distribution, but can be within the range of 0.1 to 5.0 mass% with respect to the addition amount of the polymerizable monomer.

(Surfactant)
During the polymerization reaction, a surfactant can be added from the viewpoint of preventing the resin particles in the dispersion liquid from aggregating and maintaining a good dispersion state. The specific form of the surfactant is as described above.

The particle diameter of the styrene acrylic resin particles (oil droplets) in the styrene acrylic resin particle dispersion liquid thus prepared is a volume-based median diameter of preferably 60 to 1000 nm, more preferably 80 to 500 nm. The volume-based median diameter of the oil droplets can be controlled by the magnitude of mechanical energy during emulsion dispersion.

(A-2) Crystalline polyester resin particle dispersion liquid preparation step As a method for dispersing the crystalline polyester resin in an aqueous medium, the crystalline polyester resin is dissolved or dispersed in an organic solvent (solvent) to obtain an oil phase liquid. Is prepared, the oil phase liquid is dispersed in an aqueous medium by phase inversion emulsification or the like to form oil droplets in a state where the particle size is controlled to a desired particle size, and then the organic solvent is removed.

As the organic solvent (solvent) used in the preparation of the oil phase liquid, those having a low boiling point and low solubility in water are preferable from the viewpoint of easy removal treatment after formation of oil droplets. Specific examples thereof include methyl acetate, ethyl acetate, methyl ethyl ketone, isopropyl alcohol, methyl isobutyl ketone, toluene and xylene. These can be used alone or in combination of two or more.

The amount of the organic solvent (solvent) used (the total amount used when two or more types are used) is preferably 1 to 600 parts by mass, more preferably 10 to 500 parts by mass, relative to 100 parts by mass of the resin.

Further, ammonia, sodium hydroxide or the like may be added to the oil phase liquid in order to ionically dissociate the carboxyl group and stably emulsify the water phase to promote smooth emulsification.

The amount of the aqueous medium used is preferably 50 to 2,000 parts by mass, and more preferably 100 to 1,000 parts by mass with respect to 100 parts by mass of the oil phase liquid. When the amount of the aqueous medium used is within the above range, the oil phase liquid can be emulsified and dispersed in the aqueous medium to have a desired particle size.

A dispersion stabilizer may be dissolved in the aqueous medium, and a surfactant and the like may be added for the purpose of improving the dispersion stability of oil droplets. Specific examples and suitable examples of the dispersion stabilizer and the surfactant are as described in the above section (a-1).

The emulsification and dispersion of such an oil phase liquid can be carried out by utilizing mechanical energy, and the disperser for carrying out the emulsification and dispersion is not particularly limited, and includes a low speed shearing disperser and a high speed shearing machine. Type dispersers, friction dispersers, high pressure jet dispersers, ultrasonic dispersers such as ultrasonic homogenizers, high pressure impact dispersers ultimizer, and the like.

The removal of the organic solvent after the formation of the oil droplets is carried out by gradually raising the temperature of the entire dispersion liquid in which the crystalline polyester resin particles/amorphous resin particles are dispersed in the aqueous medium in a stirring state at a constant temperature. It can be carried out by an operation such as desolventization after strong stirring in the zone. Alternatively, it can be removed under reduced pressure using a device such as an evaporator.

The average particle size of the crystalline polyester resin particles (oil droplets) (oil droplets) in the thus prepared crystalline polyester resin particle dispersion is preferably 60 to 1000 nm in terms of volume-based median diameter, and 80 More preferably, it is ˜500 nm.

(A-3) Hybrid amorphous polyester resin particle dispersion liquid preparation step In the hybrid amorphous polyester resin particle dispersion liquid preparation step, the hybrid amorphous polyester resin that constitutes the toner particles is synthesized, and the hybrid amorphous polyester resin is prepared. This is a step of preparing a dispersion liquid of hybrid amorphous polyester resin particles by dispersing the resin in the form of fine particles in an aqueous medium.

The method for producing the hybrid amorphous polyester resin is as described above. The hybrid amorphous polyester resin particle dispersion is, for example, a method of performing dispersion treatment in an aqueous medium without using a solvent (A), or dissolving or dispersing the hybrid amorphous polyester resin in an organic solvent (solvent). A method of preparing an oil phase liquid, dispersing the oil phase liquid in an aqueous medium by phase inversion emulsification, etc. to form oil droplets in a state where the particle size is controlled to a desired particle size, and then removing the organic solvent ( I) and so on.

The aqueous medium and the dispersing method in the method (a) are as described in the above section (a-1). Details of the method (i) are as described in the above section (a-2).

The particle diameter of the hybrid amorphous polyester resin particles (oil droplets) in the thus prepared hybrid amorphous polyester resin particle dispersion is a volume-based median diameter of preferably 60 to 1000 nm, more preferably 80 to 500 nm. preferable. The volume-based median diameter is measured by the method described in Examples. The volume-based median diameter of the oil droplets can be controlled by the magnitude of mechanical energy during emulsion dispersion.

(A-4) Step of preparing colorant particle dispersion liquid A colorant particle dispersion liquid is prepared by dispersing a colorant in an aqueous medium.

In order to improve the dispersion stability of the colorant particles even when the colorant particle dispersion liquid is prepared, the above-mentioned surfactant can be added. Further, the mechanical energy described above can be used for the dispersion processing.

The colorant particles in the dispersion preferably have a volume-based median diameter within the range of 10 to 300 nm, more preferably within the range of 100 to 200 nm, and even more preferably within the range of 100 to 150 nm. ..

(B) Aggregation/fusion step The prepared styrene acrylic resin particle dispersion, crystalline polyester resin particle dispersion, and colorant particle dispersion are mixed, and styrene acrylic resin particles and crystalline polyester resin particles are dispersed in an aqueous medium. The liquid and each particle of the colorant particles are aggregated. Furthermore, each particle can be fused by heating the mixed liquid to form a core particle (core portion). At the time of coagulation and fusion, a coagulation agent having a critical coagulation concentration or more is added, and the mixture is heated to the glass transition temperature (Tg) of the styrene-acrylic resin or higher to promote coagulation and fusion.

More specifically, after mixing the styrene acrylic resin particle dispersion liquid, the crystalline polyester resin particle dispersion liquid and the colorant particle dispersion liquid, a base such as an aqueous sodium hydroxide solution is previously added to the mixed liquid in order to impart cohesiveness. In addition, it is preferable to adjust the pH to 9-12.

Then, it is preferable to add the aggregating agent at 25 to 35° C. for 5 to 15 minutes while stirring. The amount of the aggregating agent used is preferably 5 to 20% by mass based on the total solid content of the binder resin particles and the colorant particles. The aggregating agent that can be used is not particularly limited, and examples thereof include metal salts such as alkali metal salts and Group 2 metal salts.

Examples of the metal salt include monovalent metal salts such as sodium chloride, potassium chloride and lithium chloride, divalent metal salts such as calcium chloride, magnesium chloride, copper sulfate and magnesium sulfate, and trivalent metals such as iron and aluminum. Salt etc. are mentioned. Among them, a divalent metal salt is preferable because it can be aggregated in a smaller amount.

In the aggregating step, it is preferable that the standing time after the coagulant is added (time until heating is started) be as short as possible. That is, it is preferable to start heating of the dispersion liquid for aggregation as soon as possible after adding the aggregating agent. The standing time is usually 30 minutes or less (lower limit 0 minute), preferably 10 minutes or less.

In addition, in the aggregating step, it is preferable to quickly raise the temperature by heating after adding the aggregating agent, and it is preferable that the rate of temperature increase is 0.8° C./min or more. The upper limit of the rate of temperature increase is not particularly limited, but it is preferably 15° C./min or less from the viewpoint of suppressing the generation of coarse particles due to the rapid progress of fusion.

Further, by maintaining the temperature for a certain period of time, preferably until the volume-based median diameter becomes 4.5 to 7.0 μm, fusion is continued.

(C) Step of Mixing Core Particle Dispersion Liquid and Hybrid Amorphous Polyester Resin Particle Dispersion Liquid and Aggregating and Fusing to Obtain Toner Particle Dispersion Liquid Dispersion of Hybrid Amorphous Polyester Resin Particles Forming Shell Part The liquid is further added, and the hybrid amorphous polyester resin forming the shell portion on the surface of the binder resin particles (core particles) obtained above is aggregated and fused. As a result, a binder resin having a core-shell structure is obtained (shell forming step). Then, when the size of the aggregated particles reaches a target size, a salt such as an aqueous solution of sodium chloride is added to stop the aggregation. After that, it is better to further heat-treat the reaction system until the aggregation and fusion of the shell portion on the surface of the core particle are strengthened and the shape of the particle becomes a desired shape (aging step). This aging step may be performed until the average circularity of the toner particles having a core-shell structure falls within a desired average circularity (preferably within the above-mentioned preferable range).

Thereby, the growth (aggregation) of particles and the fusion (disappearance of the interface between particles) can be effectively progressed, and the durability of the finally obtained toner particles can be improved.

Further, instead of the hybrid amorphous polyester resin, styrene acrylic resin may be used as the resin of the shell portion.

(D) Cooling Step This step is a step of cooling the dispersion liquid of toner particles. As the condition of the cooling treatment, it is preferable to cool at a cooling rate of 1 to 20° C./min. The specific method of the cooling treatment is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of directly charging cold water into the reaction system for cooling. it can.

(E) Filtration/Washing Step In this step, the toner particles are solid-liquid separated from the cooled dispersion liquid of the toner particles, and a toner cake obtained by the solid-liquid separation (toner particles in a wet state is aggregated into a cake shape). This is a step of removing adhering substances such as a surfactant and an aggregating agent from the collected aggregate) and washing.

The solid-liquid separation is not particularly limited, and a centrifugal separation method, a vacuum filtration method using a Nutsche or the like, a filtration method using a filter press or the like can be used.

(F) Drying Step This step is a step of drying the washed toner cake, and can be performed according to a drying step in a generally known method for producing toner particles.

Specifically, the dryer used for drying the toner cake may include a spray dryer, a vacuum freeze dryer, a vacuum dryer, and the like, a stationary shelf dryer, a mobile shelf dryer, and a fluidized bed. It is preferable to use a dryer, a rotary dryer, a stirring dryer or the like.

(G) Step of Adding External Additive This step is a step that is performed as necessary when adding an external additive to the toner particles.

As a mixing device for the external additive, a mechanical mixing device such as a Henschel mixer, a coffee mill or a sample mill can be used.

[Developer]
The toner according to the present invention may be used, for example, as a one-component magnetic toner containing a magnetic material, as a two-component developer mixed with a so-called carrier, or as a non-magnetic toner alone. Any of these can be suitably used.

As the magnetic material, for example, magnetite, γ-hematite, or various ferrites can be used.

As the carrier constituting the two-component developer, magnetic particles made of conventionally known materials such as iron, steel, nickel, cobalt, ferrite, metals such as magnetite, alloys of those metals with metals such as lead and lead are used. Can be used.

As the carrier, a coated carrier in which the surface of magnetic particles is coated with a coating agent such as resin, or a so-called resin dispersion type carrier in which magnetic powder is dispersed in a binder resin can be used. The coating resin is not particularly limited, but for example, an olefin resin, a styrene resin, a styrene acrylic resin, a silicone resin, a polyester resin, a fluororesin or the like is used. The resin for forming the resin-dispersed carrier is not particularly limited, and known ones can be used. For example, acrylic resin, styrene acrylic resin, polyester resin, fluororesin, phenol resin, etc. are used. be able to.

The volume-based median diameter of the carrier is preferably 20 to 100 μm, and more preferably 25 to 80 μm. The volume-based median diameter of the carrier can be typically measured by a laser diffraction particle size distribution analyzer “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

The mixing amount of the toner with respect to the carrier is preferably 2 to 10% by mass with the total mass of the toner and the carrier being 100% by mass.

[Image forming method]
Examples of the image forming method to which the image forming apparatus according to the present invention is applied include various known electrophotographic image forming methods. For example, it can be used for a monochrome image forming method or a full-color image forming method. The full-color image forming method includes a four-cycle image forming method including four types of color developing devices for yellow, magenta, cyan, and black, and one photoconductor, and color developing for each color. The present invention can be applied to any image forming method such as a tandem type image forming method in which an image forming unit having a device and a photoconductor is mounted for each color.

The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples.

The photochromic conductive compound used in each Example and Comparative Example is as follows. In each case, a commercial product manufactured by Tokyo Chemical Industry Co., Ltd. was used.

(Melting point (Tm) of crystalline polyester resin and glass transition temperature (Tg) of amorphous resin)
The melting point (Tm) of the crystalline polyester resin and the glass transition temperature (Tg) of the amorphous resin were obtained by using a differential scanning calorimeter (manufactured by Shimadzu Corporation: DSC-60A) according to ASTM D3418. The melting point of indium and zinc was used to correct the temperature of the detector of this device (DSC-60A), and the heat of fusion of indium was used to correct the heat quantity. An aluminum pan was used as a sample, an empty pan was set as a control, the temperature was raised at a heating rate of 10° C./min, and the temperature was held at room temperature to 150° C. for 5 minutes, and liquid nitrogen was used from 150° C. to 0° C. The temperature was lowered at −10° C./min, the temperature was held at 0° C. for 5 minutes, and the temperature was raised from 0° C. to 200° C. at 10° C./min. The onset temperature was set to Tg for the amorphous resin, and the peak top temperature of the endothermic peak was set to the melting point for the crystalline polyester resin by analyzing from the endothermic curve during the second temperature rise.

(Volume-based median diameter of resin particles, colorant particles, etc.)
The volume-based median diameters of resin particles, colorant particles, release agents, etc. were measured with a laser diffraction/scattering particle size distribution measuring device (Microtrac particle size distribution measuring device “UPA-150” (manufactured by Nikkiso Co., Ltd.)). ..

(Weight average molecular weight (Mw) of resin)
The weight average molecular weight (Mw) of each resin contained in the binder resin was measured by the following measuring method using gel permeation chromatography (GPC).

That is, using an apparatus “HLC-8220” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn+TSKgelSuperHZM-M3 series” (manufactured by Tosoh Corporation) while maintaining the column temperature at 40° C., tetrahydrofuran (THF) as a carrier solvent was used as a flow rate. Flowed at 0.2 mL/min. The measurement sample was dissolved in tetrahydrofuran so as to have a concentration of 1 mg/mL under dissolution conditions in which treatment was performed for 5 minutes using an ultrasonic disperser at room temperature (25°C). Then, a sample solution is obtained by treating with a membrane filter having a pore size of 0.2 μm, 10 μL of this sample solution is injected into the apparatus together with the above-mentioned carrier solvent, and the sample is detected using a refractive index detector (RI detector) and measured. The molecular weight distribution of the sample was calculated using a calibration curve measured using monodisperse polystyrene standard particles. As the standard polystyrene sample for measuring the calibration curve, the molecular weights manufactured by Pressure Chemical Co., Ltd. are 6×10 ² , 2.1×10 ³ , 4×10 ³ , 1.75×10 ⁴ , 5.1×10 ⁴ , and 1. The calibration curve was obtained by measuring at least about 10 points of a standard polystyrene sample using 1×10 ⁵ , 3.9×10 ⁵ , 8.6×10 ⁵ , 2×10 ⁶ , and 4.48×10 ^6. It was created. A refractive index detector was used as the detector.

[Toner 1]
(Preparation of Amorphous Vinyl Resin Particle Dispersion Liquid 1)
(First stage polymerization)
A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen introducing device was charged with 8 parts by mass of sodium dodecyl sulfate and 3000 parts by mass of ion-exchanged water, while stirring at a stirring speed of 230 rpm under a nitrogen stream, while stirring. The temperature was raised to 80°C. After the temperature was raised, a solution prepared by dissolving 10 parts by mass of potassium persulfate in 400 parts by mass of ion-exchanged water was added, the liquid temperature was again set to 80° C., and a mixed liquid of the following monomers was added dropwise over 1 hour.

Styrene 480.0 parts by mass n-butyl acrylate 250.0 parts by mass Methacrylic acid 68.0 parts by mass.

After dropping, polymerization was performed by heating and stirring at 80° C. for 2 hours to prepare a basic particle dispersion liquid (1).

(Second-stage polymerization)
A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube and a nitrogen introducing device was charged with a solution prepared by dissolving 8.67 parts by mass of sodium polyoxyethylene (2) dodecyl ether sulfate in 1352 parts by mass of ion-exchanged water. , Heated to 98°C. After heating, 55 parts by mass of the basic particle dispersion liquid (1) prepared by the above-mentioned first-stage polymerization in terms of solid content, and the following monomer, chain transfer agent and releasing agent were dissolved at 90° C. And were added.

Styrene (St) 211.44 parts by mass 2-Ethylhexyl acrylate (2EHA) 83.34 parts by mass Methacrylic acid 80% by mass aqueous solution (MAA80) 32.04 parts by mass (methacrylic acid solid content 25.63 parts by mass)
n-octyl-3-mercaptopropionate (chain transfer agent) 3.33 parts by mass N-252 (release agent, Chukyo Yushi Co., Ltd.) 172.8 parts by mass Diarylethene compound (1) 133.3 parts by mass.

Next, a mechanical dispersion machine CLEARMIX (registered trademark) (manufactured by M Technique Co., Ltd.) having a circulation path was subjected to a mixing dispersion treatment for 1 hour to prepare a dispersion liquid containing emulsified particles (oil droplets). To this dispersion was added a solution of a polymerization initiator in which 6.07 parts by mass of potassium persulfate was dissolved in 115.4 parts by mass of deionized water, and the system was heated and stirred at 84° C. for 1 hour. Polymerization was carried out to prepare a basic particle dispersion liquid (2).

(Third stage polymerization)
A solution in which 9.5 parts by mass of potassium sulfate was dissolved in 180 parts by mass of ion-exchanged water was added to the basic particle dispersion liquid (2) obtained by the second-stage polymerization. Furthermore, under a temperature condition of 82° C., a mixed liquid of the following monomer and chain transfer agent was added dropwise over 1 hour.

Styrene (St) 301.7 parts by weight Butyl acrylate (BA) 145.09 parts by weight 80% by weight methacrylic acid aqueous solution (MAA80) 35.64 parts by weight (methacrylic acid solid content 28.52 parts by weight)
Methyl methacrylate (MMA) 43.11 parts by mass n-octyl-3-mercaptopropionate 7.01 parts by mass.

After completion of the dropwise addition, the mixture was heated and stirred for 2 hours for polymerization, and then cooled to 28° C. to prepare an amorphous vinyl resin dispersion liquid 1.

The amorphous vinyl resin particles 1 in the dispersion had a volume-based median diameter of 220 nm, a weight average molecular weight (Mw) of 32000, and a solid content of 30% by mass.

The Tg of the resin obtained by the second-stage polymerization was 36.5°C, and the Tg of the resin obtained by the third-stage polymerization was 42.5°C. Here, the Tg of these resins is the designed Tg of Fox. In addition, it was confirmed that the measured value did not significantly change from the measured value measured at a temperature rising rate of 10° C./min.

(Preparation of resin particle dispersion for shell)
A mixture liquid of the following styrene-acrylic resin monomer, a monomer (acrylic acid) having a substituent that reacts with both the amorphous polyester resin and the styrene-acrylic resin, and a polymerization initiator was placed in a dropping funnel. It was

Styrene 80.0 parts by mass n-butyl acrylate 20.0 parts by mass Acrylic acid 10.0 parts by mass Di-t-butyl peroxide (polymerization initiator) 16.0 parts by mass.

Further, the following amorphous polyester resin monomer was placed in a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and heated to 170° C. to dissolve it.

Bisphenol A propylene oxide 2 mol adduct 285.7 parts by mass Terephthalic acid 66.9 parts by mass Fumaric acid 47.4 parts by mass.

Then, under stirring, the mixed solution placed in the dropping funnel was dropped into a four-necked flask over 90 minutes, and after aging for 60 minutes, unreacted monomers were removed under reduced pressure (8 kPa). .. Then, 0.4 parts by mass of Ti(OBu) ₄ as an esterification catalyst was added, the temperature was raised to 235° C., and the pressure was reduced to normal pressure (101.3 kPa) for 5 hours. , The reaction was carried out.

Then, the reaction solution was cooled to 200° C., and the reaction was performed under reduced pressure (20 kPa), followed by solvent removal, and the amorphous polyester polymer segment was grafted with styrene-acrylic resin as a main chain. An amorphous polyester resin was obtained. The weight average molecular weight (Mw) of the obtained hybrid amorphous polyester resin was 25,000, and the glass transition point (Tg) was 60°C.

100 parts by mass of the obtained hybrid amorphous polyester resin was dissolved in 400 parts by mass of ethyl acetate (manufactured by Kanto Chemical Co., Inc.), and 638 parts by mass of a 0.26% by mass concentration aqueous sodium lauryl sulfate solution prepared in advance. Mixed with. While stirring the mixed solution, ultrasonic dispersion treatment was performed with an ultrasonic homogenizer US-150T (manufactured by Nippon Seiki Seisakusho Co., Ltd.) at V-LEVEL 300 μA for 30 minutes. After that, in a state of being heated to 40° C., a diaphragm vacuum pump V-700 (manufactured by BUCHI) was used, ethyl acetate was completely removed while stirring under reduced pressure for 3 hours, and a solid content was 13.5 mass. % Hybrid amorphous polyester resin particle dispersion was prepared. The hybrid amorphous polyester resin particles in the dispersion had a volume-based median diameter of 160 nm.

(Preparation of colorant particle dispersion)
While stirring a solution prepared by adding 90 parts by mass of sodium dodecyl sulfate to 1600 parts by mass of ion-exchanged water, 420 parts by mass of copper phthalocyanine (CI Pigment Blue 15:3) was gradually added. A colorant particle dispersion liquid was prepared by performing a dispersion treatment using a stirrer Clearmix (manufactured by M Technique Co., Ltd.). The colorant particles in the dispersion had a volume-based median diameter of 110 nm.

(Production of Toner 1)
Into a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling pipe, 540 parts by mass of the amorphous vinyl resin particle dispersion liquid 1 prepared above (solid content conversion) and 332 parts by mass of ion-exchanged water were charged. At room temperature (25° C.), a 5 mol/L sodium hydroxide aqueous solution was added to adjust the pH to 10.

Furthermore, 31 parts by mass of the colorant particle dispersion liquid (solid content conversion) was added, and a solution prepared by dissolving 72.5 parts by mass of magnesium chloride in 72.5 parts by mass of ion-exchanged water was stirred at 30° C. for 10 minutes. It was added over. After standing for 3 minutes, the temperature was raised to 80° C. over 60 minutes, and after reaching 80° C., the stirring speed was adjusted so that the particle size growth rate was 0.01 μm/min, and the Coulter Multisizer 3( It was grown until the volume-based median diameter measured by Beckman Coulter, Inc. reached 6.0 μm.

Next, 60 parts by mass of the resin particle dispersion liquid for shell part prepared above (solid content conversion) was added over 30 minutes, and when the supernatant of the reaction liquid became transparent, 94.6 parts by mass of sodium chloride was added to the ions. An aqueous solution dissolved in 378.4 parts by mass of exchanged water was added to stop the growth of the particle size. Next, the temperature is raised and the mixture is agitated at a temperature of 80° C., whereby the fusion of the particles proceeds, and when the average circularity of the toner particles reaches 0.970, the cooling rate is 2.5° C./min. Cooled to 30°C. The average circularity was measured by using a measuring device FPIA-3000 (manufactured by Sysmex) with the number of HPF detections being 4000.

Next, solid-liquid separation and dehydration of the toner cake are redispersed in ion-exchanged water, and solid-liquid separation is repeated three times for washing. After washing, the toner base particles were obtained by drying at 40° C. for 24 hours.

To 100 parts by mass of the obtained toner base particles, 0.6 parts by mass of hydrophobic silica particles (number average primary particle size: 12 nm, hydrophobicity: 68) and hydrophobic titanium oxide particles (number average primary particle size: 20 nm) , Hydrophobicity: 63) 1.0 part by mass, and 1.0 part by mass of sol-gel silica (number average primary particle size=110 nm,) were added, and a rotor blade peripheral speed was obtained by a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.). It mixed at 35 mm/sec and 32 degreeC for 20 minutes. After mixing, coarse particles were removed using a sieve having an opening of 45 μm to obtain Toner 1.

[Toner 2]
(Preparation of Amorphous Vinyl Resin Particle Dispersion Liquid 2)
In the preparation of the amorphous vinyl resin particle dispersion 1, the composition ratio of the monomers used in the second-stage polymerization and the third-stage polymerization is set to the following composition, and the addition amount of the diarylethene compound (1) is 133.3. Amorphous vinyl resin particle dispersion liquid 2 was obtained in the same manner except that the amount was changed from 20 parts by mass to 20 parts by mass.

(Second-stage polymerization)
Styrene (St) 239.9 parts by mass 2-ethylhexyl acrylate (2EHA) 94.59 parts by mass 80% methacrylic acid aqueous solution (MAA80) 36.37 parts by mass (methacrylic acid solid content 29.09 parts by mass)
n-octyl-3-mercaptopropionate (chain transfer agent) 3.78 parts by mass N-252 (release agent, manufactured by Chukyo Yushi Co., Ltd.) 172.8 parts by mass Diarylethene compound (1) 20 parts by mass.

(Third stage polymerization)
Styrene (St) 324.5 parts by mass Butyl acrylate (BA) 164.7 parts by mass 80% methacrylic acid aqueous solution (MAA80) 40.46 parts by mass (methacrylic acid solid content 32.37 parts by mass)
Methyl methacrylate (MMA) 40.46 parts by mass n-octyl-3-mercaptopropionate 7.96 parts by mass.

(Production of Toner 2)
Toner 2 was manufactured in the same manner as in Toner 1 except that amorphous vinyl resin particle dispersion liquid 1 was changed to amorphous vinyl resin particle dispersion liquid 2.

[Toner 3]
(Preparation of Amorphous Vinyl Resin Particle Dispersion Liquid 3)
In the preparation of the amorphous vinyl resin particle dispersion 1, the composition ratio of the monomers used in the second-stage polymerization and the third-stage polymerization is set to the following composition, and the addition amount of the diarylethene compound (1) is 133.3. Amorphous vinyl resin particle dispersion liquid 3 was obtained in the same manner except that the amount was changed from 40 parts by mass to 40 parts by mass.

(Second-stage polymerization)
Styrene (St) 234.9 parts by mass 2-ethylhexyl acrylate (2EHA) 92.61 parts by mass 80% methacrylic acid aqueous solution (MAA80) 35.61 parts by mass (methacrylic acid solid content 28.49 parts by mass)
n-octyl-3-mercaptopropionate (chain transfer agent) 3.70 parts by mass N-252 (release agent, Chukyo Yushi Co., Ltd.) 172.8 parts by mass Diarylethene compound (1) 40 parts by mass.

(Third stage polymerization)
Styrene (St) 335.3 parts by mass Butyl acrylate (BA) 161.2 parts by mass 80% methacrylic acid aqueous solution (MAA80) 39.6 parts by mass (methacrylic acid solid content 31.69 parts by mass)
Methyl methacrylate (MMA) 47.9 parts by mass n-octyl-3-mercaptopropionate 7.79 parts by mass.

(Production of Toner 3)
Toner 3 was manufactured in the same manner as in Toner 1, except that amorphous vinyl resin particle dispersion liquid 1 was changed to amorphous vinyl resin particle dispersion liquid 3.

[Toner 4]
(Preparation of Amorphous Vinyl Resin Particle Dispersion Liquid 4)
In the preparation of the amorphous vinyl resin particle dispersion 1, the composition ratio of the monomers used in the second-stage polymerization and the third-stage polymerization is set to the following composition, and the addition amount of the diarylethene compound (1) is 133.3. Amorphous vinyl resin particle dispersion liquid 4 was obtained in the same manner except that the amount was changed from 240 parts by mass to 240 parts by mass.

(Second-stage polymerization)
Styrene (St) 184.6 parts by mass 2-Ethylhexyl acrylate (2EHA) 72.7 parts by mass 80% by mass methacrylic acid aqueous solution (MAA80) 27.9 parts by mass (methacrylic acid solid content 22.4 parts by mass)
n-octyl-3-mercaptopropionate (chain transfer agent) 2.90 parts by mass N-252 (release agent, Chukyo Yushi Co., Ltd.) 172.8 parts by mass Diarylethene compound (1) 240 parts by mass.

(Third stage polymerization)
Styrene (St) 263.4 parts by mass Butyl acrylate (BA) 126.6 parts by mass Methacrylic acid 80% by mass aqueous solution (MAA80) 31.1 parts by mass (methacrylic acid solid content 24.9 parts by mass)
Methyl methacrylate (MMA) 37.6 parts by mass n-octyl-3-mercaptopropionate 6.12 parts by mass.

(Production of Toner 4)
Toner 4 was manufactured in the same manner as in Toner 1, except that amorphous vinyl resin particle dispersion liquid 1 was changed to amorphous vinyl resin particle dispersion liquid 4.

[Toner 5]
(Preparation of Amorphous Vinyl Resin Particle Dispersion 5)
In the preparation of the amorphous vinyl resin particle dispersion 1, the composition ratio of the monomers used in the second-stage polymerization and the third-stage polymerization is set to the following composition, and the addition amount of the diarylethene compound (1) is 133.3. Amorphous vinyl resin particle dispersion liquid 5 was obtained in the same manner except that the amount was changed from 30 parts by mass to 306.7 parts by mass.

(Second-stage polymerization)
Styrene (St) 167.7 parts by mass 2-ethylhexyl acrylate (2EHA) 66.1 parts by mass 80% by mass methacrylic acid aqueous solution (MAA80) 25.4 parts by mass (methacrylic acid solid content 20.3 parts by mass)
n-octyl-3-mercaptopropionate (chain transfer agent) 2.64 parts by mass N-252 (release agent, manufactured by Chukyo Yushi Co., Ltd.) 172.8 parts by mass Diarylethene compound (1) 306.7 parts by mass.

(Third stage polymerization)
Styrene (St) 239.4 parts by mass Butyl acrylate (BA) 115.1 parts by mass Methacrylic acid 80% by mass aqueous solution (MAA80) 28.3 parts by mass (methacrylic acid solid content 22.6 parts by mass)
Methyl methacrylate (MMA) 34.2 parts by mass n-octyl-3-mercaptopropionate 5.56 parts by mass.

(Production of Toner 5)
Toner 5 was manufactured in the same manner as in Toner 1, except that amorphous vinyl resin particle dispersion liquid 1 was changed to amorphous vinyl resin particle dispersion liquid 5.

[Toner 6]
(Preparation of Amorphous Vinyl Resin Particle Dispersion Liquid 6)
In the preparation of the amorphous vinyl resin particle dispersion 1, the composition ratio of the monomers used in the second-stage polymerization and the third-stage polymerization is set to the following composition, and the addition amount of the diarylethene compound (1) is 133.3. Amorphous vinyl resin particle dispersion liquid 6 was obtained in the same manner except that the amount was changed from 150 parts by mass to 150 parts by mass.

(Second-stage polymerization)
Styrene (St) 207.2 parts by mass 2-ethylhexyl acrylate (2EHA) 81.7 parts by mass 80% by mass methacrylic acid aqueous solution (MAA80) 31.4 parts by mass (methacrylic acid solid content 25.1 parts by mass)
n-octyl-3-mercaptopropionate (chain transfer agent) 3.26 parts by mass N-252 (release agent, Chukyo Yushi Co., Ltd.) 172.8 parts by mass Diarylethene compound (1) 150 parts by mass.

(Third stage polymerization)
Styrene (St) 295.7 parts by mass Butyl acrylate (BA) 142.2 parts by mass Methacrylic acid 80% by mass aqueous solution (MAA80) 34.9 parts by mass (methacrylic acid solid content 27.9 parts by mass)
Methyl methacrylate (MMA) 42.2 parts by mass n-octyl-3-mercaptopropionate 6.87 parts by mass.

(Preparation of crystalline polyester resin particle dispersion)
315 parts by mass of 1,10-decanedicarboxylic acid (dodecanedioic acid) and 252 parts by mass of 1,9-nonanediol were placed in a reaction vessel equipped with a stirrer, a thermometer, a cooling pipe and a nitrogen gas introducing pipe. After substituting the reaction vessel with dry nitrogen gas, 0.1 parts by mass of titanium tetrabutoxide was added, and a polymerization reaction was carried out for 8 hours while stirring at 180° C. under a nitrogen gas stream. Further, 0.2 parts by mass of titanium tetrabutoxide was added, the temperature was raised to 220° C., and the polymerization reaction was carried out for 6 hours while stirring. Then, the pressure in the reaction vessel was reduced to 10 mmHg, and the reaction was performed under reduced pressure to obtain crystalline polyester resin particles. The weight average molecular weight (Mw) of the obtained crystalline polyester resin was 14000, and the melting point (Tm) was 72°C.

After 200 parts by mass of the crystalline polyester resin obtained above was dissolved in 200 parts by mass of ethyl acetate heated to 70° C., sodium polyoxyethylene lauryl ether sulfate was added to 800 parts by mass of ion-exchanged water to a concentration of 1% by mass. The mixture was mixed with an aqueous solution that had been dissolved, and dispersed using an ultrasonic homogenizer. After removing ethyl acetate from this solution under reduced pressure, the solid content concentration was adjusted to 20% by mass. As a result, a crystalline polyester resin particle dispersion liquid in which particles of the crystalline polyester resin were dispersed in the aqueous medium was prepared. The volume average particle diameter (Mv) of the crystalline polyester resin particles was 200 nm.

(Production of Toner 6)
In the production of Toner 1, the amorphous vinyl resin particle dispersion liquid 1 is changed to the amorphous vinyl resin particle dispersion liquid 6, and the amount of the amorphous vinyl resin particle dispersion liquid 6 charged is 540 parts by mass in terms of solid content. Toner 6 was manufactured in the same manner except that the amount was changed to 480 parts by mass, and 60 parts by mass of the crystalline polyester resin particle dispersion liquid prepared above was added in terms of solid content at the stage of charging before heating.

[Toner 7]
(Preparation of Amorphous Vinyl Resin Particle Dispersion Liquid 7)
In the preparation of the amorphous vinyl resin particle dispersion 1, the composition ratio of the monomers used in the second-stage polymerization and the third-stage polymerization is set to the following composition, and the addition amount of the diarylethene compound (1) is 133.3. Amorphous vinyl resin particle dispersion liquid 7 was obtained in the same manner except that the amount was changed from 142.8 parts by mass to 142.8 parts by mass.

(Second-stage polymerization)
Styrene (St) 209.0 parts by mass 2-ethylhexyl acrylate (2EHA) 82.4 parts by mass Methacrylic acid 80% by mass aqueous solution (MAA80) 31.7 parts by mass (methacrylic acid solid content 25.3 parts by mass)
n-octyl-3-mercaptopropionate (chain transfer agent) 3.29 parts by mass N-252 (release agent) 172.8 parts by mass Diarylethene compound (1) 142.8 parts by mass.

(Third stage polymerization)
Styrene (St) 298.3 parts by mass Butyl acrylate (BA) 143.5 parts by mass 80% by mass aqueous solution of methacrylic acid (MAA80) 35.2 parts by mass (methacrylic acid solid content 28.2 parts by mass)
Methyl methacrylate (MMA) 42.6 parts by mass n-octyl-3-mercaptopropionate 6.93 parts by mass.

(Production of Toner 7)
In the production of Toner 1, the amorphous vinyl resin particle dispersion liquid 1 is changed to the amorphous vinyl resin particle dispersion liquid 7, and the amount of the amorphous vinyl resin particle dispersion liquid 7 charged is from 540 parts by mass in terms of solid content. Toner 7 was manufactured in the same manner except that the amount was changed to 480 parts by mass and the crystalline polyester resin particle dispersion liquid was added in an amount of 36 parts by mass in terms of solid content at the stage of charging before heating.

[Toner 8]
(Preparation of Amorphous Vinyl Resin Particle Dispersion Liquid 8)
In the preparation of the amorphous vinyl resin particle dispersion 1, the composition ratio of the monomers used in the second-stage polymerization and the third-stage polymerization is set to the following composition, and the addition amount of the diarylethene compound (1) is 133.3. Amorphous vinyl resin particle dispersion liquid 8 was obtained in the same manner except that the amount was changed from 16 parts by mass to 164.4 parts by mass.

(Second-stage polymerization)
Styrene (St) 203.6 parts by mass 2-Ethylhexyl acrylate (2EHA) 80.3 parts by mass Methacrylic acid 80% by mass aqueous solution (MAA80) 30.9 parts by mass (methacrylic acid solid content 24.7 parts by mass)
n-octyl-3-mercaptopropionate (chain transfer agent) 3.29 parts by mass N-252 (release agent) 172.8 parts by mass Diarylethene compound (1) 164.4 parts by mass.

(Third stage polymerization)
Styrene (St) 290.6 parts by mass Butyl acrylate (BA) 139.7 parts by mass Methacrylic acid 80% by mass aqueous solution (MAA80) 34.3 parts by mass (methacrylic acid solid content 27.5 parts by mass)
Methyl methacrylate (MMA) 41.5 parts by mass n-octyl-3-mercaptopropionate 6.75 parts by mass.

(Production of Toner 8)
In the production of Toner 1, the amorphous vinyl resin particle dispersion liquid 1 is changed to an amorphous vinyl resin particle dispersion liquid 8, and the amount of the amorphous vinyl resin particle dispersion liquid 8 charged is 540 parts by mass in terms of solid content. Toner 8 was manufactured in the same manner except that the amount was changed to 438 parts by mass and the crystalline polyester resin particle dispersion liquid was added in an amount of 102 parts by mass in terms of solid content at the stage of charging before temperature rising.

[Toner 9]
(Preparation of amorphous vinyl resin particle dispersion 9)
Amorphous vinyl resin particle dispersion liquid 9 was obtained in the same manner as in the above-mentioned preparation of amorphous vinyl resin particle dispersion liquid 6, except that diarylethene compound (1) was changed to diarylethene compound (2).

(Production of Toner 9)
Toner 9 was manufactured in the same manner as in Toner 6 except that amorphous vinyl resin particle dispersion liquid 6 was changed to amorphous vinyl resin particle dispersion liquid 6.

[Toner 10]
(Preparation of Amorphous Vinyl Resin Particle Dispersion Liquid 10)
Amorphous vinyl resin particle dispersion liquid 10 was obtained in the same manner as in the above-mentioned production of amorphous vinyl resin particle dispersion liquid 6, except that diarylethene compound (1) was changed to diarylethene compound (3).

(Production of Toner 10)
Toner 10 was manufactured in the same manner as in Toner 6 in Example 6, except that amorphous vinyl resin particle dispersion liquid 6 was changed to amorphous vinyl resin particle dispersion liquid 10.

[Toner 11]
(Preparation of Amorphous Vinyl Resin Particle Dispersion 11)
In the production of the amorphous vinyl resin particle dispersion liquid 6, the composition ratio of the monomers used in the second-stage polymerization and the third-stage polymerization is set to the following composition, and the photochromic conductive compound (1) is replaced with the fulgide compound (1 Amorphous vinyl resin particle dispersion liquid 11 was obtained in the same manner except that it was changed to ).

(Production of Toner 11)
Toner 11 was manufactured in the same manner as in Toner 6, except that amorphous vinyl resin particle dispersion 6 was changed to amorphous vinyl resin particle dispersion 11.

[Toner 12]
(Preparation of Amorphous Vinyl Resin Particle Dispersion Liquid 12)
In the production of the amorphous vinyl resin particle dispersion 1, the composition ratio of the monomers used in the second-stage polymerization and the third-stage polymerization is as follows, and the addition amount of the diarylethene compound (1) is 133.3. Amorphous vinyl resin particle dispersion 12 was obtained in the same manner except that the amount was changed from 0 parts by mass to 0 parts by mass.

(Second-stage polymerization)
Styrene (St) 245.0 parts by mass 2-ethylhexyl acrylate (2EHA) 96.6 parts by mass 80% by mass methacrylic acid aqueous solution (MAA80) 37.1 parts by mass (methacrylic acid solid content 29.7 parts by mass)
n-octyl-3-mercaptopropionate (chain transfer agent) 3.86 parts by mass N-252 (release agent) 172.8 parts by mass.

(Third stage polymerization)
Styrene (St) 349.7 parts by mass Butyl acrylate (BA) 168.2 parts by mass Methacrylic acid 80% by mass aqueous solution (MAA80) 41.3 parts by mass (methacrylic acid solid content 33.0 parts by mass)
Methyl methacrylate (MMA) 49.9 parts by mass n-octyl-3-mercaptopropionate 8.12 parts by mass.

(Production of Toner 12)
Other than changing the amorphous vinyl resin particle dispersion liquid 1 (540 parts by mass (solid content conversion)) to the amorphous vinyl resin particle dispersion liquid 12 (540 parts by mass (solid content conversion)) in the production of Toner 1. In the same manner, Toner 12 was manufactured.

[Toner 13]
(Preparation of Amorphous Vinyl Resin Particle Dispersion Liquid 13)
In the production of the amorphous vinyl resin particle dispersion 1, the composition ratio of the monomers used in the second-stage polymerization and the third-stage polymerization is as follows, and the addition amount of the diarylethene compound (1) is 133.3. Amorphous vinyl resin particle dispersion liquid 13 was obtained in the same manner except that the weight part was changed to 0 part by weight.

(Second-stage polymerization)
Styrene (St) 234.8 parts by mass 2-ethylhexyl acrylate (2EHA) 106.8 parts by mass 80% by mass aqueous solution of methacrylic acid (MAA80) 37.1 parts by mass (methacrylic acid solid content 29.7 parts by mass)
n-octyl-3-mercaptopropionate (chain transfer agent) 3.80 parts by mass N-252 (release agent) 172.8 parts by mass.

(Third stage polymerization)
Styrene (St) 328.0 parts by mass Butyl acrylate (BA) 192.9 parts by mass Methacrylic acid 80% by mass aqueous solution (MAA80) 41.3 parts by mass (methacrylic acid solid content 33.0 parts by mass)
Methyl methacrylate (MMA) 46.9 parts by mass n-octyl-3-mercaptopropionate 8.06 parts by mass.

The Tg of the resin obtained by the second-stage polymerization was 30.0°C, and the Tg of the resin obtained by the third-stage polymerization was 35°C. Here, the Tg of the resin obtained by the second-stage polymerization and the third-stage polymerization is the designed Tg of Fox.

(Production of Toner 13)
Other than changing the amorphous vinyl resin particle dispersion liquid 1 (540 parts by mass (solid content conversion)) to the amorphous vinyl resin particle dispersion liquid 13 (540 parts by mass (solid content conversion)) in the production of Toner 1. In the same manner, Toner 13 was manufactured.

[Development of developer]
19 g of the carrier and 1 g of the toner prepared above were put in a 20 ml glass container and shaken at a normal temperature and normal humidity (NN) environment 200 times per minute for 20 minutes with a swing angle of 45° and an arm of 50 cm to prepare a developer.

[Adhesion power]
The sticking force was measured by using "bizhub PRESS (registered trademark) C1070 (manufactured by Konica Minolta Co., Ltd.)" and sequentially loading the developers prepared above for evaluation. The fixing device was modified so as to be a device configured by appropriately modifying the device shown in FIG. 2 so that the presence or absence of irradiation of ultraviolet light or visible light, irradiation intensity, and irradiation time could be adjusted. The temperature of the upper fixing belt was set to 150° C., the temperature of the lower fixing roller was set to 70° C., and pressure was applied at 1254 N to perform fixing. A solid image (toner adhesion amount: 10.5 g/m ² ) was output on both sides of 100 sheets (paper type: OK top coated paper (manufactured by Oji Paper Co., Ltd.) A3 157 g/m ² ). From the stacked output images, the 11th to 70th to 80th sheets are extracted, placed on a flat table as shown in FIG. 3, and a tape is attached to the tip of the short side of the top sheet. I slid it slowly in the horizontal direction. At this time, the second and subsequent images from the top were fixed to the table so that they would not move. The force (N) required to slide the paper was measured with a spring. This measurement was repeated five times from the top, and the average value of the forces exhibited by the springs was taken as the sticking force. When the sticking force was less than 2.0 N, it was set to a practical level. The results are shown in the table below. The wavelength of the ultraviolet light emitted from the first irradiation unit 40a in FIG. 2 was 365 nm (light source: LED light source with an emission wavelength of 365 nm±10 nm), the irradiation light amount was 500 mW/cm ² , and the irradiation time was 10 seconds. .. The wavelength of visible light emitted from the second irradiation unit 40b was 600 nm (light source: LED light source having an emission wavelength of 600 nm±2 nm), the irradiation light amount was 100 mW/cm ² , and the irradiation time was 5 seconds.

◎: 0 N or more and less than 1.5 N,
◯: 1.5 N or more and less than 2.0 N,
X: 2.0 N or more.

[Low temperature fixability (under offset property)]
The low-temperature fixing property was evaluated by sequentially loading the developing device prepared above into a developing device of a commercially available color multifunction machine “bizhub PRO (registered trademark) C6500 (manufactured by Konica Minolta Co., Ltd.)”. The fixing device was modified so as to be a device configured by appropriately modifying the device shown in FIG. 2, and the low-temperature fixability under the condition of being irradiated with ultraviolet light was evaluated. The irradiation conditions of the ultraviolet light are the same as the irradiation conditions at the time of measuring the sticking force. The fixing temperature, the toner adhesion amount, and the system speed were modified so that they could be freely set. Using NPI 128 g/m ² (manufactured by Nippon Paper Industries Co., Ltd.) as an evaluation paper, a solid image with a toner adhesion amount of 11.3 g/m ² is fixed at a fixing speed of 300 mm/sec, the temperature of the upper fixing belt is 110 to 200° C., the lower fixing roller. The lower limit temperature of fixing of the upper fixing belt at which under-offset does not occur when the temperature is set to 100° C. and fixing is performed at a level of 1° C. is used as an index of low-temperature fixability. Under-offset refers to an image defect that is peeled off from a transfer material such as recording paper because the toner layer is not sufficiently melted by heat applied when passing through a fixing device. The lower the fixing lower limit temperature, the better the fixability, and a pass of less than 150° C. was determined.

◎: less than 145°C,
◯: 145°C or higher and lower than 150°C,
Δ: 150°C or higher and lower than 155°C,
X: 155°C or higher.

[Amount of charge]
19 g of the carrier and 1 g of the toner prepared above were put in a 20 ml glass container and shaken at a normal temperature and normal humidity (NN) environment 200 times per minute for 20 minutes with a swing angle of 45° and an arm of 50 cm, followed by a blow-off method. The charge amount was measured.

Specifically, using a blow-off charge amount measuring device “TB-200 (manufactured by Toshiba Chemical Co., Ltd.)”, a sample to be measured is set in the blow-off charge amount measuring device equipped with a 400-mesh stainless screen, The charge was measured by blowing with nitrogen gas for 10 seconds under a blow pressure of 50 kPa. The charge amount (μC/g) was calculated by dividing the measured charge by the flying toner mass. If the charge amount is 60 μC/g or more, it can be used without any problem.

⊚: 75 to 85 μC/g,
◯: 70 μC/g or more and less than 75 μC/g,
Δ: 60 μC/g or more and less than 70 μC/g,
X: less than 60 μC/g.

[Heat resistant storage]
0.5 g of the toner prepared above was placed in a 10 ml glass bottle having an inner diameter of 21 mm, the lid was closed, and the mixture was shaken 600 times at room temperature with Tapdenser KYT-2000 (manufactured by Seishin Enterprise Co., Ltd.), and then the lid was removed. It was left for 2 hours in an environment of 5° C. and 35% RH. Next, the toner is placed on a 48-mesh sieve (opening 350 μm), being careful not to crush the toner aggregates, set on a powder tester (manufactured by Hosokawa Micron Co., Ltd.), and fixed with a holding bar and a knob nut. After adjusting the vibration strength of the feed width of 1 mm and applying vibration for 10 seconds, the ratio (% by mass) of the amount of toner remaining on the sieve was measured.

The toner aggregation rate is a value calculated by the following formula.

The heat resistant storage stability of the toner was evaluated according to the criteria described below and used as an index of the heat resistant storage stability.

⊚: The toner aggregation rate is less than 15% by mass (the heat-resistant storage stability of the toner is extremely good),
◯: Toner aggregation rate is 15% by mass or more and less than 35% by mass (heat resistant storage property of toner is good),
Δ: Toner aggregation rate is 35% by mass or more and less than 50% by mass (heat-resistant storage property of toner is slightly inferior, but acceptable level)
X: The toner agglomeration rate is 50% by mass or more (the toner has poor heat-resistant storability and cannot be used)

[Volume resistance]
To 0.1 mg of the toner prepared above was irradiated with light of 365 nm (light source: LED light source having an emission wavelength of 365 nm±10 nm) under the conditions of 25° C. and 50% RH. The irradiation light amount was 1000 mW/cm ² , and the irradiation time was 5 seconds. After UV irradiation, the volume resistance of the toner is measured by a high resistance measuring device 5451 (made by ADC Co., Ltd.) in which electrodes are installed inside a small thermostat (SH-222 made by Espec) installed in a room at 25° C. and 50% RH. Was measured at. The measurement conditions were such that the main electrode diameter was 11 mm, 1000 V was applied, the discharge time was 1 minute, the charge time was 1 second, and the measurement interval was every 10 seconds, and the sample thickness was the value measured by a digital manometer. The temperature of the small thermostat was set at 25°C for 1 minute, and then set to 100°C (temperature rising rate was 5 to 6°C/min). The measurement of the high resistance measuring device was started at the same time as the start of the temperature program, and the behavior of the volume resistivity of the measurement sample with respect to the temperature from 25° C. to 100° C. (humidity was 50% RH at any temperature) was measured. Then, the volume resistivity of the toner at 70° C. and 50% RH was obtained. In Comparative Examples 2 and 3, light irradiation was not performed. If the volume resistivity is less than 5.0×10 ¹⁶ Ω·cm, it can be used without problems.

⊚: less than 5.0×10 ¹⁴ Ω·cm,
◯: 5.0×10 ¹⁴ Ω·cm or more and less than 5.0×10 ¹⁵ Ω·cm,
Δ: 5.0×10 ¹⁵ Ω·cm or more and less than 5.0×10 ¹⁶ Ω·cm,
X: 5.0×10 ¹⁶ Ω·cm or more.

[Reflection density of image 5 minutes after fixing]
The measurement of the reflection density of the image after 5 minutes from the fixing was carried out by using "bizhub PRESS (registered trademark) C1070 (manufactured by Konica Minolta Co., Ltd.)" and sequentially loading the developers prepared above. The fixing device was modified so as to be a device configured by appropriately modifying the device shown in FIG. 2 so that the presence or absence of irradiation of ultraviolet light or visible light, irradiation intensity, and irradiation time could be adjusted. The temperature of the upper fixing belt was set to 150° C., the temperature of the lower fixing roller was set to 70° C., and pressure was applied at 1254 N to perform fixing. A solid image (toner adhesion amount: 4.0 g/m ² ) was output on 100 sheets on one side (paper type: POD gloss coat 128, manufactured by Oji Paper Co., Ltd.). The wavelength of the ultraviolet light emitted from the first irradiation unit 40a in FIG. 2 was 365 nm (light source: LED light source with an emission wavelength of 365 nm±10 nm), the irradiation light amount was 500 mW/cm ² , and the irradiation time was 10 seconds. .. The wavelength of visible light emitted from the second irradiation unit 40b was 600 nm (light source: LED light source having an emission wavelength of 600 nm±2 nm), the irradiation light amount was 100 mW/cm ² , and the irradiation time was 5 seconds. 100 sheets of continuous printing were performed under general environmental conditions (20°C, 50% RH), and 5 minutes after the output of the 100th sheet, any 8 images were printed on the solid image on the 100th printed sheet. The reflection density at the point was measured using a reflection densitometer "RD-918 (manufactured by Macbeth Co.)", and the average value was taken as the image density. If the reflection density is 1.4 or more, it can be used without problems.

Reflection density ◎: 1.8 or more,
◯: 1.6 or more and less than 1.8,
Δ: 1.4 or more and less than 1.6,
X: less than 1.4.

(Examples 1 to 12, Comparative Examples 1 to 3)
As shown in Table 1 below, the above-described evaluation was performed by variously changing the type of toner and the conditions of the fixing device. The configuration of each toner, the conditions of the fixing device, and the evaluation results are shown in Table 1 below. In Table 1, the content of the photochromic conductive compound and the content of the crystalline polyester resin are mass% values with respect to the total amount of the binder resin, the photochromic conductive compound, and the release agent contained in the toner, respectively. The content of the shell part is a value of mass% based on the total mass of the core part and the shell part.

As is clear from Table 1 above, in each of the examples, it was found that sticking of paper after continuous printing can be suppressed without deteriorating the low temperature fixing property and heat resistant storage property of the toner. On the other hand, in Comparative Example 1 in which the toner does not contain a photochromic conductive compound and in Comparative Example 3 in which the toner image formed on the paper before fixing is not irradiated with light, the paper easily sticks. Further, when a binder resin having a low glass transition temperature is used for the toner as in Comparative Example 2, the toner can be fixed at a low fixing temperature and paper sticking hardly occurs, but the heat resistant storage stability of the toner becomes low. all right.

Further, comparing Examples 1 to 5, Examples in which the content of the photochromic conductive compound is 2 to 20 mass% with respect to the total amount of the binder resin, the photochromic conductive compound, and the release agent contained in the toner. Nos. 1, 2, and 4 are excellent in the balance between the reduction in sticking force and the heat-resistant storage stability of the toner.

In addition, it was found that when a crystalline polyester resin was used as the binder resin as in Examples 6 to 10, the low temperature fixability was further improved.

In addition, as in Examples 9 to 12, the second light irradiation (visible light) causes the photochromic conductive compound to rapidly change from a colored ring-closed body to a colorless ring-opened body. Therefore, even if the content of the photochromic conductive compound is relatively large, it is considered that the blackness of the fixed image is increased in a short time after fixing and a high reflection density can be obtained.

1 photoconductor,
2 charger,
3 exposure unit,
4 development department,
5 transfer part,
7 Paper transport system,
8 cleaning section,
9 Fixing part (pressure bonding part),
10 image forming unit,
11 paper feed section,
12 transport rollers,
13 conveyor belt,
14 Paper output section,
15 Manual feed section,
16 trays,
17 Thermo-hygrometer,
20 Image processing unit,
24 Paper reversing section,
40 irradiation part,
40a 1st irradiation part (1st light irradiation means),
40b 2nd irradiation part (2nd light irradiation means),
71 image reading device,
72 automatic document feeder,
85 blades,
90 control unit,
91, 92 pressing member (pressing means),
100 image forming apparatus,
d manuscript,
S recording paper.

Claims (12)

An image forming apparatus using a toner containing a photochromic conductive compound exhibiting conductivity by an isomerization reaction due to light absorption and a binder resin,
First light irradiation means for irradiating a toner image formed from the toner arranged on the recording medium with a first light, and fixing means for fixing the light-irradiated toner image. An image forming apparatus having. The image forming apparatus according to claim 1, wherein the wavelength of the first light is 300 nm or more and less than 400 nm. The image forming apparatus according to claim 1, further comprising a second light irradiation unit that irradiates the toner image fixed on the recording medium by the fixing unit with a second light. The image forming apparatus according to claim 3, wherein the wavelength of the second light is 400 nm or more and less than 800 nm. The image according to any one of claims 1 to 4, wherein the photochromic conductive compound is a compound that photoisomerizes from a ring-opened product to a ring-closed product by irradiation with light having a wavelength of 300 nm or more and less than 400 nm. Forming equipment. The image forming apparatus according to claim 1, wherein the photochromic conductive compound is a diarylethene compound or a fulgide compound. The toner further contains a release agent, and the content of the photochromic conductive compound in the toner is 2 to 20% by mass with respect to the total amount of the binder resin, the photochromic conductive compound, and the release agent contained in the toner. The image forming apparatus according to claim 1, wherein The content of the photochromic conductive compound in the toner is 5 to 10 mass% with respect to the total amount of the binder resin, the photochromic conductive compound, and the release agent contained in the toner. Image forming apparatus. The image forming apparatus according to claim 1, wherein the binder resin includes a crystalline polyester resin. The toner further contains a release agent, and the content of the crystalline polyester resin is 5 to 20 mass% with respect to the total amount of the binder resin, the photochromic conductive compound, and the release agent contained in the toner. The image forming apparatus according to claim 9. An image forming method using a toner containing a photochromic conductive compound, which exhibits conductivity by an isomerization reaction due to light absorption, and a binder resin,
A first light irradiation step of irradiating a toner image formed of the toner arranged on a recording medium with a first light; and a fixing step of fixing the toner image irradiated with the light. An image forming method having. A toner containing a binder resin and a photochromic conductive compound exhibiting conductivity by an isomerization reaction due to light absorption.