JP6610332B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus, and more particularly to an image forming apparatus capable of suppressing image defects over a long period of time.

Conventionally, an electrostatic latent image formed on a photoreceptor is developed with toner to form a toner image, the formed toner image is transferred to a sheet of paper, and the transferred toner image is heated and fixed on the sheet of paper. There is known an electrophotographic image forming apparatus for forming an image.
In such an image forming apparatus, in order to fix a toner image on a sheet by heat fixing, it is necessary to heat the toner to a high temperature and melt it once. For this reason, there is a limit to energy saving.

  In recent years, a developer containing a compound that undergoes a cis-trans isomerization reaction by light absorption and undergoes phase transition has been disclosed in order to save energy during image formation (see, for example, Patent Document 1). In Patent Document 1, as a fixing method using such a developer, light is irradiated to a toner image transferred to a sheet, a compound that undergoes phase transition by light absorption is melted, and then light is irradiated again. A technique for fixing a toner image on a sheet by solidifying the compound is disclosed.

  Further, Patent Document 2 discloses an image forming apparatus in which a developer containing a compound that undergoes phase transition by light absorption is used. As an example, when forming an image on a recording sheet made of a transparent resin, an image is provided with an exposure device that irradiates light toward a nip position where the conveyance belt is sandwiched between the photosensitive member and the transfer roller. A device has been proposed.

Therefore, in the course of studying an image forming apparatus in which a developer containing a compound that undergoes a phase transition by light absorption is used, the present inventors irradiate light toward the toner image on the photoreceptor and absorb the light. After melting the phase transition compound, a method of transferring the toner image onto a sheet was devised.
However, in a system in which light is applied to a toner image on a photoconductor and the toner image is directly transferred onto a sheet (direct transfer system), toner remaining on the photoconductor after transfer (hereinafter referred to as “transfer residual toner”). Is also melted by light irradiation and is not in a solid state but in a semi-solid state. Therefore, when a conventional photoconductor is used, transfer residual toner adheres to the surface of the photoconductor, resulting in an image defect. A problem arises.

JP 2014-191078 A JP 2014-191077 A

  The present invention has been made in view of the above-described problems and situations, and the problem to be solved is to suppress the transfer residual toner melted by light irradiation from adhering to the photoreceptor and to suppress image defects over a long period of time. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

As a result of intensive studies on the causes of the above problems and the like in order to solve the above problems, the present inventors have found that the phenomenon that the transfer residual toner adheres to the photoconductor is a phenomenon in which the toner that has been melted by light irradiation and becomes a semi-solid state is exposed to light. As a result, it was found that the surface roughness and hardness of the photosensitive member are important for suppressing the adhesion of the transfer residual toner to the photosensitive member. .
That is, the subject concerning this invention is solved by the following means.

1. An image forming apparatus using a developer containing a compound that undergoes a phase transition by light absorption,
A photoreceptor on which an electrostatic latent image is formed;
A developing unit that develops the electrostatic latent image formed on the photoreceptor with the developer to form a toner image;
A first irradiation unit that irradiates the toner image on the photosensitive member with ultraviolet light having a wavelength of 300 nm or more and less than 400 nm;
A transfer unit that transfers the toner image irradiated with ultraviolet light by the first irradiation unit to a recording medium;
With
The photoreceptor has a maximum surface roughness Rz of 0.020 to 0.060 μm and a universal hardness HU in a range of 220 N / mm ^{2 to} 240 N / mm ^2. Image forming apparatus.

2. The photoreceptor includes a protective layer as an outermost layer,
2. The image forming apparatus according to item 1, wherein the protective layer contains inorganic fine particles.

  3. 3. The image forming apparatus according to claim 1, wherein the protective layer of the photoconductor contains an ultraviolet absorber.

  4). The first irradiation unit includes a second irradiation unit that irradiates visible light having a wavelength of 400 nm or more and 800 nm or less to the developer on the photosensitive member irradiated with ultraviolet light by the first irradiation unit. Item 4. The image forming apparatus according to any one of Items 3 to 3.

  5. 5. The apparatus according to any one of claims 1 to 4, further comprising a third irradiation unit that irradiates the toner image transferred to the recording medium with ultraviolet light having a wavelength of 300 nm or more and less than 400 nm. The image forming apparatus described in 1.

  6). 6. The apparatus according to any one of claims 1 to 5, further comprising a fourth irradiation unit that irradiates the toner image transferred to the recording medium with visible light having a wavelength of 400 nm to 800 nm. The image forming apparatus described in 1.

  According to the image forming apparatus of the present invention, it is possible to suppress the transfer residual toner melted by the light irradiation from being fixed to the photosensitive member by the above-described means, and to suppress image defects over a long period of time.

The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.
In the system in which light is irradiated onto a photoreceptor holding a toner image containing a compound that undergoes phase transition by light absorption, and the toner image is directly transferred to a recording medium, the toner is melted by light irradiation. It is in a semi-solid state, not a state. That is, in the toner containing a compound that undergoes phase transition by light absorption, the untransferred toner is in a specific state as compared with the conventional toner. For this reason, when a conventional photoconductor is used, a phenomenon occurs in which the untransferred toner adheres to the surface of the photoconductor. In particular, in the static layer in the cleaning area, the toner remaining after transfer is in a semi-solid state, and thus it is difficult to obtain toner fluidity and tends to be packed.

The fixing phenomenon of the transfer residual toner on the photoconductor occurs when the semi-solid toner is buried in the concave portion of the photoconductor surface. Therefore, the surface roughness and hardness of the photoconductor are important in order to suppress sticking of the transfer residual toner to the photoconductor surface. The image forming apparatus according to the present invention includes a photoconductor having a maximum height roughness Rz of 0.060 μm or less and a universal hardness HU in a range of 220 N / mm ² or more and 300 N / mm ² or less. The transfer residual toner can be effectively prevented from sticking, and image defects can be suppressed over a long period of time.

1 is a front view illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. Front view showing schematic configuration of irradiation unit in image forming apparatus Sectional view showing schematic structure of photoconductor

The image forming apparatus of the present invention is an image forming apparatus using a developer containing a compound that undergoes phase transition by light absorption, and includes a photoreceptor on which an electrostatic latent image is formed, and a static image formed on the photoreceptor. A developing unit that develops an electrostatic latent image with the developer to form a toner image, a first irradiation unit that irradiates the toner image on the photoconductor with ultraviolet light having a wavelength of 300 nm or more and less than 400 nm, A transfer unit that transfers a toner image irradiated with ultraviolet light from the first irradiation unit to a recording medium, and the photoconductor has a maximum surface roughness Rz of 0.020 to 0.060 μm. The universal hardness HU is in the range of 220 N / mm ² or more and 240 N / mm ² or less.
This feature is a technical feature common to the claimed invention. Accordingly, it is possible to provide an image forming apparatus that suppresses the sticking of the transfer residual toner to the photoreceptor and suppresses image defects over a long period of time.

  As an embodiment of the present invention, it is preferable from the viewpoint of improving the hardness of the photoreceptor and suppressing ultraviolet deterioration, the photoreceptor includes a protective layer as the outermost layer, and the protective layer contains inorganic fine particles.

  Furthermore, the protective layer of the photoreceptor preferably contains an ultraviolet absorber from the viewpoint of suppressing ultraviolet degradation.

  In addition, a second irradiation unit that irradiates the developer on the photosensitive member irradiated with ultraviolet light by the first irradiation unit with visible light having a wavelength of 400 nm to 800 nm is provided on the photosensitive member. This is preferable from the viewpoint of more effectively expressing the adhesion of the transfer residual toner.

  In addition, it is preferable from the viewpoint of improving fixability to include a third irradiation unit that irradiates the toner image transferred to the recording medium with ultraviolet light having a wavelength of 300 nm or more and less than 400 nm.

  In addition, the fourth irradiation unit that irradiates visible light having a wavelength of 400 nm or more and 800 nm or less to the toner image transferred to the recording medium includes an offset when the image is pressed onto the recording medium by the pressing unit. It is preferable from the viewpoint of eliminating the problem and improving the fixing property.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, "-" shown in the following invention is used in the meaning which contains the numerical value described before and behind as a lower limit and an upper limit.

[Image forming apparatus]
FIG. 1 is a schematic configuration diagram of an image forming apparatus 100 according to the present invention. However, the image forming apparatus used in the present invention is not limited to the following forms 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. An image is formed by the forming unit 10, the crimping unit 9, and the first irradiation unit 40a.
As an embodiment of the present invention, it is preferable that the image forming apparatus further includes a second irradiation unit 40b, a third irradiation unit 40c, and a fourth irradiation unit 40d shown in FIG. 2 in addition to the above configuration. Hereinafter, when the first irradiation unit to the fourth irradiation unit are collectively referred to as the irradiation unit 40.

Further, although the image forming apparatus 100 uses paper as a recording medium, any medium other than paper may be used as long as it is a target for image formation.
The document d placed on the document table of the automatic document feeder 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, and the like in the image processing unit 20 and then input to the exposure device 3 of the image forming unit 10. The

  The paper transport system 7 includes a plurality of trays 16, a plurality of paper feeding units 11, a transport roller 12, a transport belt 13, and the like. The tray 16 accommodates recording paper S of a determined size, and operates the paper supply unit 11 of the tray 16 determined according to an instruction from the control unit 90 to supply the recording paper S. The transport roller 12 transports the recording paper S sent out 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 includes a charger 2, an exposure unit 3, a developing unit 4, a transfer unit 5, a charge removal unit 6, and a cleaning unit 8 in this order around the photoconductor 1 along the rotation direction of the photoconductor 1. Arranged and configured.
A photoconductor 1 as an image carrier is an image carrier having a photoconductive layer formed on the surface thereof, and is configured to be rotatable in a direction of an arrow in FIG. 1 by a driving device (not shown). A thermohygrometer 17 that detects the temperature and humidity in the image forming apparatus 100 is provided in the vicinity of the photoreceptor 1.

The charger 2 uniformly charges the surface of the photoreceptor 1 and charges the surface of the photoreceptor 1 uniformly.
The exposure device 3 includes a beam emission source such as a laser diode, and the charged surface of the photosensitive member 1 is irradiated with beam light so that the charge on the irradiated portion disappears. An electrostatic latent image is formed.
The developing unit 4 supplies toner contained therein to the photoconductor 1 to form a toner image based on the electrostatic latent image on the surface of the photoconductor 1.

The first irradiation unit 40a irradiates the toner image formed on the photoreceptor 1 with ultraviolet light, thereby melting the compound that undergoes phase transition by light absorption contained in the toner image.
The configuration of the first irradiation unit 40a will be described in detail below.
The transfer unit 5 faces the photoreceptor 1 through the recording paper S, and transfers the toner image irradiated with the ultraviolet light by the first irradiation unit 40a to the recording paper S.
The neutralization unit 6 performs neutralization on the photoreceptor 1 after the toner image is transferred.
The cleaning unit 8 includes a blade 85. The surface of the photoreceptor 1 is cleaned by the blade 85 to remove the developer remaining on the surface of the photoreceptor 1.

The recording paper S to which the toner image has been transferred is conveyed to the crimping section 9 by the conveying belt 13.
The pressure bonding unit 9 applies a fixing process to the recording paper S on which the toner image is transferred by applying heat and pressure or pressure only by the fixing roller 91 and the pressure roller 92, thereby fixing the image on the recording paper S. Let The recording sheet S on which the image is fixed is transported to the paper discharge unit 14 by the transport roller, and is discharged from the paper discharge unit 14 to the outside of the apparatus.

  Further, the image forming apparatus 100 includes a sheet reversing unit 24, and the recording sheet S that has been heat-fixed is conveyed to the sheet reversing unit 24 before the paper discharge unit 14, and is discharged with the front and back reversed. Alternatively, the recording sheet S with the front and back reversed can be conveyed again to the image forming unit 10 to form an image on both sides of the recording sheet S.

[Irradiation part]
FIG. 2 is a schematic configuration diagram of the irradiation unit 40 in the image forming apparatus 100.
The image forming apparatus 100 of the present invention includes an irradiation unit 40 including a first irradiation unit 40a, a second irradiation unit 40b, a third irradiation unit 40c, and a fourth irradiation unit 40d.
As an example of what constitutes the irradiation unit 40, a light emitting diode (LED), a laser beam, and the like can be given.

The first irradiation section 40a and the third irradiation section 40c are for melting a compound (a UV phase transition material described later) that undergoes phase transition by light absorption contained in the developer, and preferably within a range of 300 nm to less than 400 nm. Emits ultraviolet light having a wavelength in the range of 330 nm or more and less than 390 nm. The dose of the first irradiation unit 40a and the third irradiation unit 40c is, for example, in the range of 0.1 to 200 J / cm ² , preferably in the range of 0.5 to 100 J / cm ² , and more preferably 1. It is in the range of 0-50 J / cm ² .

The second irradiation part 40b and the fourth irradiation part 40d solidify the ultraviolet phase transition material, and emit visible light having a wavelength in the range of 400 nm to 800 nm, preferably in the range of 450 nm to 650 nm. Exit. The irradiation amount of the second irradiation unit 40b and the fourth irradiation unit 40d is, for example, 0.1 to 200 J / cm ² , preferably 0.5 to 100 J / cm ² , and more preferably 1.0 to 50 J / cm ^2. It is.
The first irradiation unit 40 a emits the ultraviolet light toward the toner image on the photoconductor 1 and is disposed so as to face the surface of the photoconductor 1. The first irradiation unit 40 a is disposed on the downstream side of the photosensitive member rotation method with respect to the developing unit 4 and on the upstream side of the photosensitive member rotation direction with respect to the nip position N between the photosensitive member 1 and the transfer roller 50. . Further, the first irradiation unit 40 a is disposed on the photoconductor side with respect to the recording paper S surface nipped between the photoconductor 1 and the transfer roller 50.

  The second irradiation unit 40b emits the visible light toward the developer on the photosensitive member 1 irradiated with ultraviolet light by the first irradiation unit 40a, and faces the surface of the photosensitive member 1. Has been placed. The second irradiation unit 40 b is disposed on the downstream side in the photoconductor rotation direction with respect to the nip position between the photoconductor 1 and the transfer roller 50 and on the upstream side with respect to the blade 85 in the photoconductor rotation direction. Further, the second irradiation unit 40 b is disposed on the photosensitive member side with respect to the recording paper S surface nipped between the photosensitive member 1 and the transfer roller 50.

The third irradiation unit 40c and the fourth irradiation unit 40d emit light toward the first surface on the photoconductor side of the recording paper S holding the toner image irradiated with the ultraviolet light by the first irradiation unit 40a. The recording sheet S surface nipped between the photosensitive member 1 and the transfer roller 50 is disposed on the photosensitive member side.
Further, the third irradiation unit 40c and the fourth irradiation unit 40d are arranged in this order along the conveyance direction (paper conveyance direction) of the recording paper S.
The third irradiation unit 40 c is disposed on the downstream side in the paper conveyance direction with respect to the nip position between the photoconductor 1 and the transfer roller 40 and on the upstream side in the paper conveyance direction with respect to the crimping unit 9.

  The fourth irradiation unit 40d is installed on the downstream side in the paper conveyance direction with respect to the third irradiation unit 40c and on the upstream side in the paper conveyance direction with respect to the paper discharge unit 14. The fourth irradiation unit 40d can be installed between the third irradiation unit 40c and the pressure bonding unit 9 or at least one of the pressure bonding unit 9 and the paper discharge unit 14 in the paper transport direction. Moreover, the 4th irradiation part 40d can be installed in the both sides via the crimping | compression-bonding part 9 in a paper conveyance direction.

[Photoreceptor]
The photoreceptor 1 has a maximum surface roughness Rz of 0.060 μm or less and a surface universal hardness (HU) in the range of 220 to 300 N / mm ² .
The maximum height roughness Rz of the surface of the photoconductor 1 is 0.060 μm or less, and since there are few irregularities on the surface of the photoconductor, the transfer residual toner melted by light irradiation is suppressed from being buried in the photoconductor recesses. Can do. Therefore, it is possible to effectively suppress the transfer residual toner from adhering to the surface of the photoreceptor, and to suppress image defects over a long period of time.
The lower limit of the maximum height roughness Rz is preferably 0.020 μm or more. If it is 0.020 μm or more, the contact area between the photoreceptor 1 and the blade 85 can be reduced, and the occurrence of turning of the blade 85 can be suppressed.

The high-hardness photoconductor 1 having a universal hardness (HU) of 220 N / mm ² or more can suppress wear and deterioration of the photoconductor surface due to durability, and the transfer melted by light irradiation in the concave portion of the photoconductor surface. It is possible to effectively prevent the remaining toner from being buried and fixed.
On the other hand, if the universal hardness is too high, the deteriorated layer formed by oxidation of the surface of the photoreceptor cannot be removed, and an image flow is likely to occur. However, the universal hardness of the photoreceptor 1 is 300 N / mm ² or less. The surface of the photoreceptor is moderately worn by a cleaning device such as the blade 85, and the deteriorated layer can be scraped off. As described above, since the surface of the photoconductor is depleted and refreshed, it is possible to suppress the occurrence of image flow. From the above viewpoint, the universal hardness (HU) is more preferably in the range of 220 to 260 N / mm ² , and still more preferably in the range of 220 to 240 N / mm ² .

The maximum height roughness Rz of the surface of the photoreceptor 1 can be calculated from a surface roughness curve measured according to JIS B0601: 2013. The roughness curve can be measured by a stylus type surface roughness measuring device based on JIS B0601: 2013, a non-contact type surface analyzing device using a laser or the like.
The measurement conditions when using a stylus type surface roughness measuring apparatus include the following conditions.

(Measurement condition)
Measuring device: Surfcom 1400D (manufactured by Tokyo Seimitsu Co., Ltd.)
Measurement mode: Roughness measurement Measurement length: 20.0 mm
Cut-off: 0.08mm (Gaussian)
Measurement speed: 0.15 mm / sec

The photoconductor 1 having the maximum height roughness Rz within the above range can be manufactured, for example, by polishing or processing the surface of the photoconductor 1.
Further, the universal hardness (HU) of the surface of the photoreceptor 1 can be measured by a Fischer scope H100 (a hardness test system manufactured by Fischer Instruments Inc. conforming to ISO / FDIS14577).
Specifically, in the Fischer scope H100, a load F (N) is applied stepwise to a square pyramid diamond indenter with a facing angle of 136 ° (maximum load 2 mN), and the indenter is pushed into the sample. From the indentation depth h (mm) and load F, universal hardness (HU) is calculated by the following formula.
HU (N / mm ² ) = F / (26.43 × h ² )
The photoreceptor 1 includes a protective layer as the outermost layer, and the protective layer contains the binder resin and the inorganic fine particles, whereby the photoreceptor 1 having a universal hardness (HU) within the above range can be obtained.

FIG. 3 is a cross-sectional view showing a schematic configuration of the photoreceptor 1.
As shown in FIG. 3, the photoreceptor 1 includes an intermediate layer 32, a photosensitive layer 33, and a protective layer 34 in this order on a drum-shaped conductive support 31.

[Protective layer]
The protective layer 34 is provided as the outermost layer of the photoreceptor 1 from the viewpoint of protecting the photoreceptor 1 from external force. The protective layer 34 located on the outermost surface is subjected to surface processing so that the maximum height roughness Rz of the surface becomes 0.060 μm or less as described above.
The protective layer 34 preferably contains a binder resin and inorganic fine particles because the universal hardness (HU) of the photoreceptor 1 can be easily obtained.

  Examples of the binder resin include polyester resin, polycarbonate resin, polyurethane, and silicone resin. Among these, from the viewpoint of increasing the wear resistance and durability of the photoreceptor 1, a cured resin obtained by polymerizing and curing a polymerizable compound by irradiation with active rays such as ultraviolet rays and electron beams is preferable. A curable resin and a non-cured resin can be used in combination.

(Cured resin)
As the polymerizable compound that can be used in the cured resin, a monomer having two or more polymerizable functional groups (polyfunctional polymerizable compound) can be used, and a monomer having one polymerizable functional group (monofunctional polymerizable compound). ) Can be used in combination.
As the polymerizable compound, a monomer having three or more polymerizable functional groups can be used. Moreover, when using together 2 or more types of polymeric compounds, it is preferable to use the monomer which has 3 or more of polymerizable functional groups in the ratio of 50 mass% or more.
Specific examples of the polymerizable compound include styrene monomers, acrylic monomers, methacrylic monomers, vinyl toluene monomers, vinyl acetate monomers, N-vinyl pyrrolidone monomers, and the like. One of these may be used alone or a plurality of types may be used in combination.

Among them, acrylic monomers having two or more acryloyl groups (CH ₂ ═CHCO—) or methacryloyl groups (CH ₂ ═CCH ₃ CO—), since these can be cured with a small amount of light or in a short time, or these It is preferable that it is an oligomer.
Examples of the polymerizable compound include the following exemplary compounds (M1) to (M15), but polymerizable substances that can be used in the present invention are not limited thereto.
In the following exemplified compounds (M1) to (M15), R represents an acryloyl group (CH ₂ ═CHCO—), and R ′ represents a methacryloyl group (CH ₂ ═CCH ₃ CO—).

(Polymerization initiator)
Examples of a method for polymerizing a polymerizable compound that can be used for the protective layer 34 include a method using an electron beam cleavage reaction and a method using light and heat in the presence of a radical polymerization initiator.
As the radical polymerization initiator, both a photopolymerization initiator and a thermal polymerization initiator can be used, and a plurality of types can be used in combination.
As the photopolymerization initiator, an alkylphenone compound, a phosphine oxide compound or the like can be used, and a compound having an α-hydroxyacetophenone structure or an acylphosphine oxide structure is preferable. Examples of commercially available photopolymerization initiators include bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (IRGACURE819: manufactured by BASF Japan).

Examples of thermal polymerization initiators include ketone peroxide compounds, peroxyketal compounds, hydroperoxide compounds, dialkyl peroxide compounds, diacyl peroxide compounds, peroxydicarbonate compounds, and peroxyester compounds. Can be used.
Content of a polymerization initiator can be in the range of 0.1-40 mass parts with respect to 100 mass parts of polymeric compounds, Preferably it is 0.5-20 mass parts. If it exists in this range, superposition | polymerization of a polymeric compound will fully advance and the universal hardness of the surface of the photoreceptor 1 can be adjusted in the range of 220-300 N / mm < ² >.

(Radical scavenger)
In order to adjust the degree of polymerization, a radical scavenger can be used during the polymerization reaction. By adjusting the degree of polymerization, it is possible to adjust the wear of the photoreceptor surface.
As a commercial item of a radical scavenger, for example, Smither GS (manufactured by Sumitomo Chemical Co., Ltd.) and the like can be mentioned.

(Inorganic fine particles)
From the viewpoint of improving the hardness of the photoreceptor and suppressing UV degradation, the protective layer 34 preferably contains inorganic fine particles.
Examples of inorganic fine particles that can be used for the protective layer 34 include silica (silicon oxide), magnesium oxide, zinc oxide, lead oxide, alumina (aluminum oxide), zirconium oxide, tin oxide, titania (titanium oxide), niobium oxide, and oxidation. Examples thereof include inorganic fine particles such as molybdenum, vanadium oxide, and aluminum nitride. Of these, tin oxide, titanium oxide, or zinc oxide having a band gap Eg of 4.0 or less is preferable from the viewpoint of suppressing ultraviolet degradation, and tin oxide is more preferable because of excellent electrical characteristics. These may be used alone or in combination of two or more.

The method for producing the inorganic fine particles is not particularly limited, and for example, an indirect method (French method), a direct method (American method), a plasma method, etc. described in JIS K1410: 2006 can be used.
The number average primary particle size of the inorganic fine particles is preferably in the range of 1 to 300 nm, more preferably in the range of 3 to 100 nm.
The number average primary particle size of the inorganic fine particles is a photographic image (excluding aggregated particles) obtained by taking a magnified photograph of 10,000 times with a scanning electron microscope (manufactured by JEOL Ltd.) and randomly capturing 300 particles with a scanner. Can be calculated using an automatic image processing analyzer LUZEX AP (manufactured by Nireco, software version Ver. 1.32).

As the inorganic fine particles, those obtained by surface-treating the inorganic fine particles with a surface treatment agent having a reactive organic group to introduce a reactive organic group on the particle surface can be used.
As the surface treatment agent, those that react with a hydroxy group or the like present on the surface of inorganic fine particles are preferable, and examples thereof include a silane coupling agent and a titanium coupling agent.
As the surface treatment agent, it is also preferable to use a surface treatment agent having a radical polymerizable reactive group such as a vinyl group, an acryloyl group, or a methacryloyl group. Such radically polymerizable reactive groups can react with the polymerizable compound constituting the binder resin to form a strong protective layer 34. As the surface treatment agent having a radical polymerizable reactive group, a silane coupling agent having a radical polymerizable reactive group, a silane compound, and the like are preferable.

Hereinafter, exemplary compounds (S-1) to (S-30) of the surface treatment agent are shown.
_{S-1 CH 2 = CHSi (} CH 3) (OCH 3) 2
_{S-2 CH 2 = CHSi (} OCH 3) 3
S-3 CH ₂ = CHSiCl _{3
S-4 CH 2 = CHCOO (} CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-5 CH 2 = CHCOO (} CH 2) 2 Si (OCH 3) 3
_{S-6 CH 2 = CHCOO (} CH 2) 2 Si (OC 2 H 5) (OCH 3) 2
_{S-7 CH 2 = CHCOO (} CH 2) 3 Si (OCH 3) 3
_{S-8 CH 2 = CHCOO (} CH 2) 2 Si (CH 3) Cl 2
_{S-9 CH 2 = CHCOO (} CH 2) 2 SiCl 3
_{S-10 CH 2 = CHCOO (} CH 2) 3 Si (CH 3) Cl 2
S-11 CH ₂ = CHCOO (CH ₂ ) ₃ SiCl _{3
S-12 CH 2 = C (} CH 3) COO (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-13 CH 2 = C (} CH 3) COO (CH 2) 2 Si (OCH 3) 3
_{S-14 CH 2 = C (} CH 3) COO (CH 2) 3 Si (CH 3) (OCH 3) 2
_{S-15 CH 2 = C (} CH 3) COO (CH 2) 3 Si (OCH 3) 3
_{S-16 CH 2 = C (} CH 3) COO (CH 2) 2 Si (CH 3) Cl 2
_{S-17 CH 2 = C (} CH 3) COO (CH 2) 2 SiCl 3
_{S-18 CH 2 = C (} CH 3) COO (CH 2) 3 Si (CH 3) Cl 2
_{S-19 CH 2 = C (} CH 3) COO (CH 2) 3 SiCl 3
_{S-20 CH 2 = CHSi (} C 2 H 5) (OCH 3) 2
S-21 CH ₂ ═C (CH ₃ ) Si (OCH ₃ ) _{3
S-22 CH 2 = C (} CH 3) Si (OC 2 H 5) 3
_{S-23 CH 2 = CHSi (} OCH 3) 3
_{S-24 CH 2 = C (} CH 3) Si (CH 3) (OCH 3) 2
_{S-25 CH 2 = CHSi (} CH 3) Cl 2
_{S-26 CH 2 = CHCOOSi (} OCH 3) 3
_{S-27 CH 2 = CHCOOSi (} OC 2 H 5) 3
_{S-28 CH 2 = C (} CH 3) COOSi (OCH 3) 3
_{S-29 CH 2 = C (} CH 3) COOSi (OC 2 H 5) 3
_{S-30 CH 2 = C (} CH 3) COO (CH 2) 3 Si (OC 2 H 5) 3

The surface treating agent may be used alone or in combination of two or more.
The amount of the surface treatment agent used is preferably in the range of 0.1 to 200 parts by mass, more preferably in the range of 7 to 70 parts by mass with respect to 100 parts by mass of the inorganic fine particles.
Examples of the surface treatment method include a method in which a slurry (suspension of solid particles) containing inorganic fine particles, a surface treatment agent, and a solvent is wet crushed, and then the solvent is removed to form a powder. According to this method, the surface treatment of the inorganic fine particles can be advanced while preventing re-aggregation of the inorganic fine particles.
As the surface treatment apparatus, for example, a sand mill, an ultra visco mill, a pearl mill, a grain mill, a dyno mill, an agitator mill, a dynamic mill, or the like can be used.

(UV absorber)
The protective layer 34 preferably contains a UV absorber from the viewpoint of suppressing UV degradation.
As UV absorbers, benzotriazole UV absorbers, benzophenone UV absorbers, triazine UV absorbers, cyanoacrylate UV absorbers, salicylate UV absorbers, benzoate UV absorbers, diphenyl acrylate UV absorbers And known ones such as liquid ultraviolet absorbers.

The protective layer 34 can further contain an antioxidant, lubricant particles, a charge transport agent and the like from the viewpoint of electrical characteristics.
As antioxidant, the thing of Unexamined-Japanese-Patent No. 2000-305291 can be used, for example.
As the lubricant particles, fluorine atom-containing resin particles or the like can be used. As fluorine atom-containing resin particles, for example, tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluorochloroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluoroethylene dichloride resin, etc. are used. it can.

Further, as the charge transport agent, a charge transport material contained in the charge transport layer 33b described later can be used.
The thickness of the protective layer 34 is preferably in the range of 0.2 to 10 μm, and more preferably in the range of 0.5 to 6 μm, from the viewpoint of obtaining sufficient impact resistance.
The protective layer 34 can be formed by preparing a coating solution containing the above-described binder resin, inorganic fine particles and the like, applying the coating solution on the photosensitive layer 33, and then drying. When a curable resin is used as the binder resin, the protective layer 34 can be formed by forming a coating film containing a polymerizable compound, a polymerization initiator and the like on the photosensitive layer 33 and then drying and curing.

As a coating method, known methods such as a dipping method, a spray method, a spinner method, a bead method, a blade method, a beam method, a slide hopper method, and the like can be used.
Drying may be natural drying or heat drying.
When a curable resin is used as the binder resin, the coating film containing a polymerizable compound, a polymerization initiator, etc. is irradiated with actinic radiation to form a crosslink between the molecules and within the molecule to form a crosslink and harden it. preferable. As the actinic ray, ultraviolet rays and electron beams are preferable.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, a mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.
The irradiation conditions vary depending on individual lamps, irradiation of actinic rays is in the range of usually 5~500mJ / cm ^2, preferably in the range of 5 to 100 mJ / cm ^2.
The power of the lamp is preferably in the range of 0.1 to 5 kW, particularly preferably in the range of 0.5 to 3 kW.

As an electron beam source, there is no particular limitation on the electron beam irradiation apparatus, and generally, an electron beam accelerator for electron beam irradiation is a curtain beam type that is relatively inexpensive and can provide a large output. Used. The acceleration voltage during electron beam irradiation is preferably 100 to 300 kV. The absorbed dose is preferably 0.5 to 10 Mrad.
The irradiation time for obtaining the necessary amount of active ray irradiation is preferably 0.1 second to 10 minutes, and more preferably 0.1 second to 5 minutes from the viewpoint of work efficiency.
Hereinafter, each layer of the photoreceptor 1 other than the protective layer 34 will be described.

[Conductive support]
As the conductive support 31, a drum formed of a metal such as aluminum, copper, chromium, nickel, zinc, stainless steel or the like can be used as long as it has conductivity.
In addition, when the photoreceptor 1 is not in the form of a drum but in the shape of a belt, a plate, or the like, a conductive film, a conductive material such as indium oxide or tin oxide, or a resin film on which a metal film such as aluminum or copper is formed, A belt, a plate, or the like using paper or the like can also be used as the conductive support 31.

[Middle layer]
The intermediate layer 32 can be provided between the conductive support 31 and the photosensitive layer 33 as necessary from the viewpoint of improving gas barrier properties and adhesion.
The intermediate layer 32 can be formed by dissolving a binder resin in a known solvent and forming a coating film by dip coating or the like and then drying.
As the binder resin, for example, casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane, gelatin and the like can be used, and alcohol-soluble polyamide resin is particularly preferable.
The concentration of the binder resin can be appropriately selected according to the layer thickness of the intermediate layer 32 and the production rate.

  From the viewpoint of adjusting resistance, the intermediate layer 32 is made of inorganic particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide and other metal oxide particles, tin-doped indium oxide and antimony. Conductive particles such as tin oxide and zirconium oxide doped with can be contained. These inorganic particles can be used singly or in combination of two or more. When two or more are mixed, they may be in a solid solution or fused state.

The content of the inorganic particles is preferably in the range of 20 to 400 parts by mass, more preferably in the range of 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin.
The number average average particle diameter of the inorganic particles is preferably 0.3 μm or less, more preferably 0.1 μm or less.
The layer thickness of the intermediate layer 32 is preferably 0.1 to 15 μm, and more preferably 0.3 to 10 μm.

(Photosensitive layer)
As shown in FIG. 3, the photosensitive layer 33 includes a charge generation layer 33a and a charge transport layer 33b.
When the light irradiated by the exposure unit 2c reaches the photosensitive layer 33, a charge corresponding to the amount of irradiated light is generated in the charge generation layer 33a, and the charge moves in the charge transport layer 33b to move the surface of the photoreceptor 1. And an electrostatic latent image is formed.
Although the photosensitive layer 33 shown in FIG. 3 has a multilayer structure, it may have a single-layer structure containing both a charge generation material and a charge transport material.

(Charge generation layer)
The charge generation layer 33a contains a binder resin and a charge generation material that generates a charge when absorbing light energy.
The charge generation layer 33a can be formed by drying a coating film formed by dispersing and coating a charge generation material in a binder resin solution.
Examples of charge generation materials include azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as pyrenequinone and anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and polycyclic rings such as pyranthrone and diphthaloylpyrene. Examples include quinone pigments and phthalocyanine pigments. These charge generation materials can be used alone or dispersed in a known resin.
As a means for dispersing the charge generating substance, for example, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, or the like can be used.

As the binder resin, known resins can be used, for example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane, phenol resin, Polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, copolymer resin containing two or more of these resins (for example, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-anhydrous maleic acid) Acid copolymer resin, etc.), poly-vinylcarbazole resin, and the like.
The content of the charge generation material in the charge generation layer 33a is preferably in the range of 1 to 600 parts by weight, more preferably in the range of 50 to 500 parts by weight with respect to 100 parts by weight of the binder resin. is there.
The thickness of the charge generation layer varies depending on the characteristics of the charge generation material, the characteristics of the binder resin, the content, etc., but is preferably in the range of 0.01 to 5 μm, more preferably in the range of 0.05 to 3 μm. is there.

(Charge transport layer)
The charge transport layer 33b contains a binder resin and a charge transport material (also referred to as CTM: Charge Transport Material).
The charge transport layer 33b can be formed by dissolving and coating a charge transport material in a binder resin solution to form a coating film and then drying.
Examples of the charge transport material include triphenylamine derivatives, hydrazone compounds, styryl compounds, benzidine derivatives, butadiene compounds, and the like, and the following compound A.
You may use these individually or in mixture of 2 or more types.

Examples of the binder resin include polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylic ester resin, styrene-methacrylic ester copolymer resin, and the like.
Among these, polycarbonate resin is preferable, and from the viewpoint of improving crack resistance, wear resistance and charging characteristics, bisphenol A (BPA) type, bisphenol Z (BPZ) type, dimethyl BPA type, and BPA-dimethyl BPA copolymer type are preferred. A polycarbonate resin or the like is preferable.

The content of the charge transport material in the charge transport layer 33b is preferably in the range of 10 to 500 parts by weight, more preferably in the range of 20 to 250 parts by weight with respect to 100 parts by weight of the binder resin.
The layer thickness of the charge transport layer 33b varies depending on the characteristics of the charge transport material, the characteristics of the binder resin, the content, and the like, but is preferably in the range of 5 to 40 μm, more preferably in the range of 10 to 30 μm. preferable.
The charge transport layer 33b can further contain an antioxidant, an electronic conductive agent, a stabilizer, silicone oil, and the like.
As the antioxidant, materials described in JP-A No. 2000-305291 and as the electronic conductive agent can be used materials described in JP-A Nos. 50-137543 and 58-76483.

(Developer)
The developer used in the image forming apparatus of the present invention contains toner particles composed of toner base particles and external additive particles, and carrier particles. The toner base particles are compounds that undergo phase transition by light absorption (hereinafter referred to as ultraviolet rays). Also referred to as phase change material).

<toner>
The toner constituting the developer is formed from toner particles obtained by attaching external additive particles to toner base particles. Specifically, the toner base particles include at least a binder resin and an ultraviolet phase transition material, and further contain other components such as a colorant, a magnetic powder, a release agent, and a charge control agent as required. You can also.

(Binder resin)
A thermoplastic resin is preferably used as the binder resin constituting the toner particles.
As such a binder resin, those generally used as a binder resin constituting a toner can be used without particular limitation. Specifically, for example, styrene resins, alkyl acrylates, alkyl methacrylates, and the like can be used. Examples thereof include acrylic resins, styrene acrylic copolymer resins, polyester resins, silicone resins, olefin resins, amide resins, and epoxy resins.
Among these, styrene resins, acrylic resins, styrene acrylic copolymer resins, and polyester resins having low melt properties and high sharp melt properties are preferable.

(Coloring agent)
When the toner particles are configured to contain a colorant, generally known dyes and pigments can be used as the colorant.
Examples of the colorant for obtaining a black toner include carbon black, magnetic material, iron / titanium composite oxide black, and the like. Examples of the carbon black include channel black, furnace black, acetylene black, thermal black, and lamp black. Can be mentioned. Examples of the magnetic material include ferrite and magnetite.

Examples of the colorant for obtaining a yellow toner include C.I. I. Solvent Yellow 19, Dye 44, Did 77, Did 79, Did 81, Did 82, Did 93, Did 98, Did 103, Did 104, Did 112, Did 162, etc .; I. Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, 185, and the like.
Examples of the colorant for obtaining a magenta toner include C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, etc .; C.I. I. Pigment red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222, etc.
Examples of the colorant for obtaining cyan toner include C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95, etc .; C.I. I. Pigment Blue 1, 7, 15, 15, 60, 62, 66, 76 and the like.
The colorant for obtaining the toner of each color can be used singly or in combination of two or more for each color.
The content ratio of the colorant is preferably 0.5 to 20% by mass in the toner particles, and more preferably 2 to 10% by mass.

(UV phase change material)
The ultraviolet phase transition material contains a compound that undergoes a cis-trans isomerization reaction by light absorption and undergoes phase transition. The ultraviolet phase transition material undergoes a phase transition from a solid to a liquid by absorbing light having a wavelength of 300 nm or more and less than 400 nm.
Specific examples include sugar alcohol esters represented by the following general formula (1), sugar alcohol esters represented by the following general formula (2), discotic liquid crystal compounds represented by the following general formula (4), and the like. .

  In general formula (1), R is a functional group represented by the following general formula (3), and n represents an integer of 1 to 4.

  In General Formula (2), R is a functional group represented by the following General Formula (3), and n represents an integer of 1 to 4.

  In general formula (3), m shows the integer of 0-16, k shows the integer of 1-16.

In general formula (4), R ₁ , R ₂ and R ₃ are each independently hydrogen, alkyl group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, alkanoyl group, alkanoyloxy group, alkoxyphenyl group and Selected from the group consisting of N-alkylaminocarbonyl groups, n represents an integer. However, the case where all of R ₁ , R ₂ and R ₃ are hydrogen is excluded.

The sugar alcohol ester represented by the general formula (1) and the general formula (2) undergoes a phase transition from a solid to a liquid by absorbing light having a wavelength of 300 nm or more and less than 400 nm, and is 400 nm or more and 800 nm or less. Phase transition from a liquid to a solid by absorbing light having a wavelength of or by heating to 30 ° C. or higher and below the melting point of the compound.
In the general formula (3), m preferably represents an integer of 4 to 8. In the general formula (3), k preferably represents an integer of 8 to 12.
The melting point of such a sugar alcohol ester is, for example, 50 ° C. or higher and 140 ° C. or lower, preferably 60 ° C. or higher and 130 ° C. or lower.
Such sugar alcohol esters may be used alone or in combination of two or more. Among such sugar alcohol esters, the sugar alcohol ester represented by the above general formula (1) is preferable, and the sugar alcohol ester represented by the following compound B is more preferable.

In compound B, R is a functional group represented by the following chemical formula C.

In order to prepare the sugar alcohol ester having the structure represented by the general formula (1), the raw material compound having the structure represented by the general formula (3) having the azobenzene group and the following general formula (6) are represented. A sugar alcohol having a structure is reacted.
Examples of the raw material compound include azobenzene compounds represented by the following general formula (5).

  In general formula (5), m represents the same integer as m shown in the general formula (3), and k represents the same integer as k shown in the general formula (3).

The azobenzene compound having the structure represented by the above general formula (5) is obtained by reacting, for example, 4-alkyl-4′-hydroxyazobenzene with a halogen atom-containing carboxylic acid compound under alkaline conditions, as an intermediate. After preparing the carboxy group-containing azobenzene derivative, the carboxy group-containing azobenzene derivative is prepared by reacting with an acid halogenating agent.
As 4-alkyl-4'-hydroxyazobenzene, Preferably, 4-hexyl-4'-hydroxyazobenzene is mentioned.

  The halogen atom-containing carboxylic acid compound is a compound having a carboxy group and a halogen atom, for example, a halogen atom-containing carboxylic acid compound having 2 to 17 carbon atoms, preferably a halogen atom-containing carboxylic acid compound having 9 to 13 carbon atoms. Is mentioned. Moreover, as a halogen atom of a halogen atom containing carboxylic acid compound, a fluorine, chlorine, bromine, an iodine etc. are mentioned, for example, Preferably a bromine is mentioned.

  Examples of the acid halogenating agent include thionyl chloride, oxalyl chloride, phosgene, phosphorus oxychloride, phosphorus pentachloride, phosphorus trichloride, thionyl bromide, phosphorus tribromide, diethylaminosulfur trifluoride, and the like. Preferably, thionyl chloride is used.

  In general formula (6), n shows the same integer as n shown by the said general formula (1).

The sugar alcohol having the structure represented by the general formula (6) is a chain polyhydric alcohol in which the carbonyl group of the sugar is reduced. For example, tritol such as glycerin, tetritol such as threitol and erythritol, arabinitol, Examples thereof include pentitols such as xylitol and ribitol, pentitols such as galactitol, glucitol and mannitol.
Such sugar alcohols may be used alone or in combination of two or more. Of these sugar alcohols, pentitol is preferable, and mannitol is more preferable.

  In order to react the azobenzene compound having the structure represented by the general formula (5) with the sugar alcohol having the structure represented by the general formula (6), first, the structure represented by the general formula (5) is reacted. The azobenzene compound is dissolved in an organic solvent to prepare an intermediate solution, and the sugar alcohol represented by the general formula (6) is dispersed in dehydrated pyridine, for example, 0.5 to 3% by mass of sugar alcohol A suspension is prepared.

  Examples of the organic solvent include esters such as ethyl acetate and butyl acetate, ethers such as diethyl ether, diisopropyl ether, and tetrahydrofuran, ketones such as acetone and methyl ethyl ketone, and saturated carbonization such as hexane and heptane. Examples of the hydrogen include halogenated hydrocarbons such as dichloromethane, dichloroethane, and carbon tetrachloride. Such organic solvents may be used alone or in combination of two or more. Of these organic solvents, halogenated hydrocarbons are preferable, and dichloromethane is more preferable.

Next, the sugar alcohol suspension is slowly added to the intermediate solution, and then stirred, for example, at 10 to 40 ° C., for example, for 24 to 144 hours.
As a result, the azobenzene compound having the structure represented by the general formula (5) reacts with the sugar alcohol having the structure represented by the general formula (6), and the sugar alcohol having the structure represented by the general formula (1). Esters are produced.

  The discotic liquid crystal compound having the structure represented by the general formula (4) undergoes a phase transition from a solid to a liquid by absorbing light having a wavelength of 300 nm or more and less than 400 nm, and is 30 ° C. or more and below the melting point of the compound. To a phase transition from a liquid to a solid.

In the general formula (4), R ₁ is preferably an alkoxy group, more preferably an alkoxy group having 1 to 20 carbon atoms, and particularly preferably an alkoxy group having 8 to 16 carbon atoms. In the general formula (4), R ₂ and R ₃ are preferably hydrogen. Moreover, in said general formula (4), n shows the integer of 1-8, for example, Preferably, the integer of 1-4 is shown.
The melting point of such a discotic liquid crystal compound is, for example, 50 ° C. or higher and 140 ° C. or lower, and preferably 60 ° C. or higher and 130 ° C. or lower.
Such discotic liquid crystal compounds may be used alone or in combination of two or more.

  A compound having a structure represented by the general formula (4) can be generally synthesized by reductively cyclizing a dinitro compound (methylene bridged dimerized nitrobenzene derivative) as a precursor. In the synthesis, the compound having a structure represented by the general formula (4) is mainly obtained as a mixture of compounds having n of 1 to 10. By purifying the resulting mixture by gel permeation chromatography, the compound corresponding to each n can be isolated. In the compound having the structure represented by the general formula (4), as n increases, the solubility of the compound in an organic solvent decreases.

  Further, a dinitro compound (methylene bridged dimerized nitrobenzene derivative) which is a precursor of a compound having a structure represented by the general formula (4) is, for example, (a) a dimerization step of a nitrobenzene derivative with formaldehyde; And a step of introducing a substituent to the dimerized nitrobenzene derivative. Also, a dinitro compound (methylene bridged dimerized nitrobenzene derivative) may be produced by a method comprising (a ′) a step of introducing a substituent to a nitrobenzene derivative and (b ′) a dimerization step of the substituted nitrobenzene derivative with formaldehyde. Good.

(Magnetic powder)
In the case where the toner particles according to the present invention are configured to contain magnetic powder, for example, magnetite, γ-hematite, or various ferrites can be used as the magnetic powder.
The content of the magnetic powder is preferably in the range of 10 to 500% by mass in the toner particles, and more preferably in the range of 20 to 200% by mass.

(Release agent)
In the case where the toner particles according to the present invention are configured to contain a release agent, the release agent is not particularly limited, and various known waxes can be used. Examples of the wax include low molecular weight polypropylene, polyethylene, oxidized low molecular weight polypropylene, polyolefin such as polyethylene, paraffin, synthetic ester wax, and the like. In particular, a synthetic ester wax is used because of its low melting point and low viscosity. It is particularly preferable to use behenyl behenate, glycerine tribehenate, pentaerythritol tetrabehenate or the like as the synthetic ester wax.
The content of the release agent is preferably in the range of 1 to 30% by mass in the toner particles, and more preferably in the range of 3 to 15% by mass.

(Charge control agent)
In the case where the toner particles according to the present invention are configured to contain a charge control agent, the charge control agent is a substance that can be positively or negatively charged by frictional charging and is colorless. Any known positively chargeable charge control agent and negatively chargeable charge control agent can be used.
The content ratio of the charge control agent is preferably in the range of 0.01 to 30% by mass in the toner particles, and more preferably in the range of 0.1 to 10% by mass.

(Average toner particle size)
The average particle diameter of the toner is preferably in the range of 4 to 10 μm, and more preferably in the range of 6 to 9 μm, for example, in terms of volume-based median diameter (D50).
When the volume-based median diameter (D50) is in the above range, the transfer efficiency is increased, the image quality of halftone 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 (manufactured by Beckman Coulter, Inc.) equipped with data processing software “Software V3.51” in “Coulter Counter 3” (Beckman Coulter, Inc.). ) Is measured / calculated using a measuring device connected to.

Specifically, 0.02 g of a measurement sample (toner) was added to 20 mL of a surfactant solution (for example, a surfactant obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing toner particles). Solution) and ultrasonically dispersed for 1 minute to prepare a toner dispersion, and this toner dispersion is a beaker containing “ISOTON II” (manufactured by Beckman Coulter) in a sample stand. Then, inject with a pipette until the displayed concentration of the measuring device is 8%.
Here, a reproducible measurement value can be obtained by setting the concentration range. In the measuring apparatus, the measurement particle count is 25000, the aperture diameter is 50 μm, the frequency value is calculated by dividing the measurement range of 1 to 30 μm into 256, and the volume integrated fraction is 50 % Particle diameter is defined as the volume-based median diameter (D50).

<Production of toner>
The method for producing the toner is not particularly limited, but an emulsion polymerization aggregation method capable of controlling the particle diameter and shape is preferable.
In the emulsion polymerization aggregation method, the resin fine particles may be composed of two or more layers composed of resins having different compositions. In this case, the first resin prepared by emulsion polymerization treatment (first-stage polymerization) according to a conventional method. It is possible to employ a multistage polymerization method in which a polymerization initiator and a polymerizable monomer are added to a fine particle dispersion, and this system is polymerized (second stage polymerization).

Specifically showing an example of the production process when the toner is obtained by emulsion polymerization aggregation method,
(1A) a resin fine particle polymerization step for obtaining resin fine particles by allowing a radical polymerization initiator to act on a specific monomer to form a binder resin in an aqueous medium and, if necessary, another polymerizable monomer;
(1B) a colorant fine particle dispersion preparation step for preparing a dispersion of fine particles (hereinafter also referred to as “colorant fine particles”) with a colorant;
(1C) an ultraviolet phase transition material dispersion preparation step for preparing a dispersion of fine particles (hereinafter also referred to as “ultraviolet phase change material fine particles”) using an ultraviolet phase change material;
(2) An association in which an aggregating agent is added to an aqueous medium in which resin fine particles, colorant fine particles, and an ultraviolet phase transition material are present, and salting-out proceeds, and at the same time, aggregation and fusion are performed to form associated particles. Process,
(3) an aging step for forming toner by controlling the shape of the associated particles;
(4) A filtration and washing process for separating the toner particles from the aqueous medium and removing the surfactant from the toner particles.
(5) a drying step of drying the washed toner particles;
(6) An external additive adding step of adding an external additive to the dried toner particles.

Here, the “aqueous medium” refers to a medium composed of 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent. Examples of water-soluble organic solvents include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran, and alcohol-based organic solvents that do not dissolve the obtained resin such as methanol, ethanol, isopropanol, and butanol should be used. Is preferred.
As a method for incorporating a release agent in the toner particles, a method in which the resin fine particles are configured to contain a release agent, and a release agent fine particles are dispersed in an aqueous medium in an association process for forming the toner particles. And a method of salting out, agglomerating, and fusing the resin fine particles, the colorant fine particles, and the release agent fine particles. These methods may be combined.
Examples of the method of incorporating the charge control agent in the toner particles include the same method as the method of incorporating the release agent described above.

(1A) Resin fine particle polymerization step This resin fine particle polymerization step is specifically performed by adding a specific monomer and, if necessary, another polymerizable monomer in an aqueous medium, for example. Apply and disperse to form oil droplets, and in this state, a specific monomer undergoes a radical polymerization reaction to form resin fine particles having a size of, for example, a volume-based median diameter of about 50 to 300 nm. Is.
The dispersing device for imparting mechanical energy for forming oil droplets is not particularly limited. For example, a commercially-available stirring device “CLEARMIX” (M (Technique, Inc.) is a typical example. In addition to the above-described stirring device provided with a rotor capable of rotating at high speed, devices such as an ultrasonic dispersion device, a mechanical homogenizer, a manton gourin, and a pressure homogenizer can be used.

  Although the temperature which concerns on radical polymerization reaction changes also with the kind of monomer and radical polymerization initiator to be used, it is preferable that it is 50-100 degreeC, for example, More preferably, it is 55-90 degreeC. The time required for the radical polymerization reaction varies depending on the type of monomer used and the reaction rate of radicals from the radical polymerization initiator, but is preferably 2 to 12 hours, for example.

(Dispersion stabilizer)
In the resin fine particle polymerization step, an appropriate dispersion stabilizer can be added in order to stably disperse the fine particles in the aqueous medium.
Examples of the dispersion stabilizer include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, sulfuric acid. Examples include barium, bentonite, silica, and alumina. In addition, polyvinyl alcohol, gelatin, methylcellulose, sodium dodecylbenzenesulfonate, ethylene oxide adduct, higher alcohol sodium sulfate and the like which are generally used as surfactants can also be used as the dispersion stabilizer.
As such a surfactant, conventionally known various ionic surfactants, nonionic surfactants, and the like can be used.
Examples of the ionic surfactant include sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, sodium 3,3-disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol-6-sulfonate, Sulfonates such as ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sulfonate sodium; dodecyl sulfate There are sodium, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate and the like, and fatty acid salts include sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate, Sulfates of calcium phosphate and the like; fatty acid salts.
Nonionic surfactants include, for example, polyethylene oxide, polypropylene oxide, a combination of polypropylene oxide and polyethylene oxide, esters of polyethylene glycol and higher fatty acids, alkylphenol polyethylene oxide, esters of higher fatty acids and polyethylene glycol, higher fatty acids and polypropylene. Examples include oxide esters and sorbitan esters.

(Polymerization initiator)
Polymerization initiators used in the resin fine particle polymerization step include water-soluble polymerization initiators such as potassium persulfate, ammonium persulfate and azobiscyanovaleric acid, water-soluble redox polymerization initiators such as hydrogen peroxide-ascorbic acid, azo Oil-soluble polymerization initiators such as bisisobutyronitrile and azobisvaleronitrile can be used.

(Chain transfer agent)
In the resin fine particle polymerization step, a generally used chain transfer agent can be used for the purpose of adjusting the molecular weight of the specific acrylic polymer or the specific acrylic copolymer. The chain transfer agent is not particularly limited, and examples thereof include n-octyl mercaptan, n-dodecyl mercaptan, tert-dodecyl mercaptan, and tetrachloromethane.

(1B) Colorant fine particle dispersion preparation step This colorant fine particle dispersion preparation step is a step of preparing a dispersion of colorant fine particles by dispersing a colorant in the form of fine particles in an aqueous medium.
The colorant can be dispersed using mechanical energy.
The colorant fine particles preferably have a volume-based median diameter in a range of 10 to 300 nm, more preferably 100 to 200 nm, and particularly preferably 100 to 150 nm.
The volume-based median diameter of the colorant fine particles is measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.).

(1C) Ultraviolet phase change material dispersion preparation step This ultraviolet phase change material dispersion preparation step is a step of preparing a dispersion of ultraviolet phase change material fine particles by dispersing an ultraviolet phase change material in the form of fine particles in an aqueous medium. is there. In preparing the ultraviolet phase change material dispersion, first, an ultraviolet phase change material emulsion is prepared.
As a method for preparing the ultraviolet phase transition material emulsion, for example, after obtaining an ultraviolet phase transition material liquid in which the ultraviolet phase transition material is dissolved in an organic solvent, the ultraviolet phase transition material liquid is emulsified in an aqueous medium. Can be mentioned.
The method for blending the ultraviolet phase change material in the organic solvent is not particularly limited. For example, the ultraviolet phase transition material is blended in the organic solvent, and the mixture is stirred and mixed so that the ultraviolet phase transition material is dissolved.
Moreover, the compounding ratio of the ultraviolet phase transition material is, for example, 5 parts by mass or more and 100 parts by mass or less, and preferably 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the organic solvent.

Next, the ultraviolet phase transition material liquid is mixed with an aqueous medium and then stirred using a known disperser such as a homogenizer. As a result, the ultraviolet phase transition material becomes droplets and is emulsified in an aqueous medium, whereby an ultraviolet phase transition material emulsion is prepared.
The mixing ratio of the ultraviolet phase transition material liquid is, for example, 10 parts by mass or more and 90 parts by mass or less, and preferably 30 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the aqueous medium.
Further, the temperature of the ultraviolet phase transition material liquid and the aqueous medium at the time of blending the ultraviolet phase transition material liquid and the aqueous medium is a temperature range that is lower than the boiling point of the organic solvent, and is, for example, 20 ° C. or higher and 80 ° C. The temperature is preferably 30 ° C. or higher and 75 ° C. or lower. The temperature of the ultraviolet phase transition material liquid and the temperature of the aqueous medium at the time of blending the ultraviolet phase transition material liquid and the aqueous medium may be the same as or different from each other, preferably the same.
Moreover, as for the stirring conditions of a disperser, when the capacity | capacitance is 1-3L or less, it is preferable that the rotation speed is 7000 rpm or more and 20000 rpm or less, and the stirring time is 10 minutes or more and 30 minutes or less. It is preferable.

The ultraviolet phase change material dispersion is prepared by removing the organic solvent from the ultraviolet phase change material emulsion.
Examples of the method for removing the organic solvent from the ultraviolet phase transition material dispersion include known methods such as blowing, heating, decompression, or a combination thereof.
Specifically, the ultraviolet phase transition material emulsion is, for example, 25 to 90 ° C., preferably 30 to 80 ° C. in an inert gas atmosphere such as nitrogen. The organic solvent is removed by heating until about 80% by mass or more and about 95% by mass or less are removed. Thereby, the organic solvent is removed from the aqueous medium, and the ultraviolet phase change material dispersion liquid in which the ultraviolet phase change material fine particles are dispersed in the aqueous medium is prepared.

The mass average particle diameter of the ultraviolet phase change material fine particles in the ultraviolet phase change material dispersion is preferably 90 nm or more and 1200 nm or less.
The mass average particle size of the ultraviolet phase change material fine particles is the viscosity when the ultraviolet phase change material is blended in an organic solvent, the blending ratio of the UV softening material liquid and water, and the high speed disperser when preparing the UV softening material emulsion. By appropriately controlling the stirring speed and the like, it can be set within the above range.

(Organic solvent)
The organic solvent is not particularly limited as long as the UV softening material can be dissolved. For example, esters such as ethyl acetate and butyl acetate, for example, ethers such as diethyl ether, diisopropyl ether and tetrahydrofuran, such as acetone and methyl ethyl ketone. Ketones such as, for example, saturated hydrocarbons such as hexane and heptane, and halogenated hydrocarbons such as dichloromethane, dichloroethane, and carbon tetrachloride.
Such an organic solvent can also be used independently and can also be used together 2 or more types. Of these organic solvents, ketones and halogenated hydrocarbons are preferable, and methyl ethyl ketone and dichloromethane are more preferable.

(Aqueous medium)
The aqueous medium is water or an aqueous medium containing water as a main component, for example, some water-soluble solvent such as alcohols and glycols, or optional components such as surfactants and dispersants. Is mentioned. According to the above emulsification method, the aqueous medium is preferably a mixture of water and a surfactant.
Examples of the surfactant include a cationic surfactant, an anionic surfactant, and a nonionic surfactant. 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, such as sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium lauryl sulfate. Nonionic surfactants include, for example, polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene sorbitan monooleate ether, monodecanoyl Examples include sucrose.

Such surfactant can also be used independently and can also be used together 2 or more types. Of these surfactants, anionic surfactants are preferable, and sodium dodecylbenzenesulfonate is more preferable.
The blending ratio of the surfactant is, for example, 0.01 parts by mass or more and 10 parts by mass or less, preferably 0.04 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of water. About (2) association process-(6) external additive addition process, it can carry out according to a conventionally well-known various method.

(Flocculant)
The flocculant used in the association step is not particularly limited, but one selected from metal salts is preferably used. Examples of the metal salt include monovalent metal salts such as alkali metal salts such as sodium, potassium and lithium; divalent metal salts such as calcium, magnesium, manganese and copper; and trivalent metal salts such as iron and aluminum. Etc. Specific metal salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, and the like. It is particularly preferable to use a divalent metal salt. These can be used alone or in combination of two or more.

(External additive)
Although the above toner particles can constitute the toner of the present invention as they are, in order to improve fluidity, chargeability, cleaning properties, etc., a fluidizing agent which is a so-called post-treatment agent is added to the toner particles. An external additive such as a cleaning aid may be added to constitute the toner of the present invention.
Examples of the external additive include inorganic oxide fine particles composed of silica fine particles, alumina fine particles, titanium oxide fine particles, etc., inorganic stearate compound fine particles such as aluminum stearate fine particles, zinc stearate fine particles, or strontium titanate, titanium. Examples thereof include inorganic titanic acid compound fine particles such as zinc oxide. These can be used alone or in combination of two or more.

These inorganic fine particles are preferably subjected to a surface treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil or the like in order to improve heat-resistant storage stability and environmental stability.
The total amount of these various external additives added is 0.05 to 5 parts by mass, preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the toner particles. In addition, various external additives may be used in combination.

(Development of developer)
The developer can be obtained by mixing the carrier and the toner using a mixing device.
The mixing amount of the toner with respect to the carrier is preferably 2 to 10% by mass.
The mixing device for mixing the toner and the carrier is not particularly limited, and examples thereof include a Nauter mixer, a W cone, and a V-shaped mixer.

As the carrier, magnetic particles made of conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used, and ferrite particles are particularly preferable.
Further, as the carrier, a coat carrier in which the surface of the magnetic particles is coated with a coating agent such as a resin, a binder type carrier in which a magnetic fine powder is dispersed in a binder resin, or the like may be used.

The coating resin constituting the coat carrier is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene-acrylic resins, silicone resins, ester resins, and fluorine resins. Moreover, it does not specifically limit as resin which comprises a resin dispersion type carrier, A well-known thing can be used, For example, a styrene-acrylic-type resin, a polyester resin, a fluororesin, a phenol resin etc. can be used.
The volume-based median diameter of the carrier is preferably in the range of 20 to 100 μm, and more preferably in the range of 20 to 60 μm. The volume-based median diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

(Image forming method)
The image forming apparatus 100 of the present invention can be used in various well-known electrophotographic image forming methods. For example, it can be used in a monochrome image forming method or a full color image forming method. In the full-color image forming method, a four-cycle image forming method including four types of color developing devices for each of yellow, magenta, cyan, and black and one photoconductor, and color developing for each color. Any image forming method such as a tandem image forming method in which an image forming unit having an apparatus and a photoreceptor is mounted for each color can be used.

As an image forming method, the charging device 2 applies a uniform potential to the photosensitive member 1 to charge it, and then scans the photosensitive member 1 with a light beam emitted from the exposure device 3 based on the original image data. An electrostatic latent image is formed. Next, a developer containing a compound that undergoes phase transition by light absorption is supplied onto the photoreceptor 1 by the developing unit 4.
By the time the toner image carried on the surface of the photoconductor 1 reaches the position of the transfer roller 50 by the rotation of the photoconductor 1, the first irradiation unit 40 a has the toner image carried on the surface of the photoconductor 1. On the other hand, ultraviolet light having a wavelength in the range of 300 nm or more and less than 400 nm is irradiated. When the toner image on the photoreceptor 1 is irradiated with ultraviolet light from the first irradiation unit 40a, the ultraviolet phase transition material included in the toner image is melted. Note that the above process is performed before the image is formed on the recording paper S.

When the recording sheet S is conveyed from the tray 16 to the image forming unit 10 in accordance with the timing at which the toner image exposed by the first irradiation unit 40a reaches the position of the transfer roller 50 by the rotation of the photosensitive member 1, the transfer roller 50 receives the recording sheet S. The toner image on the photoreceptor 1 is transferred onto the recording sheet S nipped between the transfer roller 50 and the photoreceptor 1 by the applied transfer bias.
By the time the toner image on the photoconductor is transferred onto the recording paper S, the developer held on the photoconductor 1 is irradiated with ultraviolet light by the first irradiation unit 40a. In the melted state, the light receiving surface comes into contact with the first surface of the recording paper S on the photoreceptor side, and the toner image is transferred to the recording paper S. As described above, the light receiving surface of the toner image melted by the first irradiation unit 40a serves as a contact surface with the recording paper S, so that the document offset and the transfer rate can be effectively improved.

The transfer roller 50 also serves as a pressure member, and can transfer the toner image from the photoreceptor 1 to the recording paper S, while ensuring that the ultraviolet phase change material contained in the toner image is in close contact with the recording paper S. Can be made.
After the toner image is transferred to the recording paper S, the blade 85 of the cleaning unit 8 removes the developer remaining on the surface of the photoreceptor 1. Since the toner on the photoconductor 1 irradiated with ultraviolet light from the first irradiation unit 40a is melted and in a semi-solid state, the transfer residual toner in the semi-solid state is easily buried and fixed on the surface of the photoconductor 1. In the image forming apparatus of the invention, since the surface of the photosensitive member 1 has the specific maximum height roughness Rz and universal hardness (HU), it is possible to suppress the transfer residual toner from being fixed to the surface of the photosensitive member 1. Image defects can be suppressed over a long period of time.

  Further, the second irradiation unit 40b can be provided in order to more reliably suppress the sticking of the transfer residual toner to the photoconductor. The second irradiation unit 40b irradiates the developer melted by the first irradiation unit 40a remaining on the photoreceptor 1 after the transfer with visible light having a wavelength of 400 nm or more and 800 nm or less. When visible light is irradiated by the second irradiation unit 40b, the melted toner image is solidified and becomes a solid state, so that the transfer residual toner can be more reliably prevented from sticking to the surface of the photoreceptor 1. .

  In the process in which the recording paper S to which the toner image has been transferred is transported to the pressure-bonding unit 9 by the transport belt 13, the third irradiation unit 40 c is 300 nm or more and less than 400 nm with respect to the toner image transferred onto the recording paper S. Irradiate ultraviolet light having a wavelength. The toner image irradiated with ultraviolet light by the first irradiation unit 40a has a surface in contact with the recording sheet S, which is the light receiving surface thereof, mainly in a melted state. Furthermore, the recording sheet is further recorded by the third irradiation unit 40c. By irradiating the toner image on the first surface of S with ultraviolet light, the toner image can be more reliably melted and the fixability of the toner image to the recording paper S can be improved.

When the recording paper S on which the toner image is held reaches the pressure bonding unit 9 by the transport belt 13, the fixing roller 91 and the pressure roller 92 press the image against the first surface of the recording paper S. Since the toner image is melted by ultraviolet light irradiation by the first irradiation unit 40a and the third irradiation unit 40c before the fixing process is performed by the pressure bonding unit 9, energy saving can be achieved when the image is bonded to the recording paper S. Can do.
Before the recording paper S holding the toner image irradiated with the ultraviolet light by the third irradiation unit 40c is passed between the fixing roller 91 and the pressure roller 92, the fourth irradiation unit 40d The toner image is irradiated with visible light having a wavelength of 400 nm to 800 nm. By irradiating visible light with the fourth irradiation unit 40d, the surface on the photoreceptor side in the toner image melted by the first irradiation unit 40a and the third irradiation unit 40c can be solidified, and the fixing roller 91 and The developer can be prevented from adhering to the pressure roller 92, that is, the offset at the time of pressure bonding.

  Further, the visible light having a wavelength of 400 nm or more and 800 nm or less with respect to the toner image on the recording paper S until the recording paper S passing between the fixing roller 91 and the pressure roller 92 reaches the paper discharge unit 14. The fourth irradiation unit 40d can be provided so as to irradiate. By irradiating visible light with the fourth irradiation section 40d, the toner image on the recording paper S can be solidified more reliably, and the fixing property of the toner image to the recording paper S can be further improved. From the viewpoint of eliminating offset at the time of pressure bonding and improving fixability, it is preferable to install the fourth irradiation unit 40d at both the front and rear positions of the pressure bonding portion in the paper transport direction.

The fixing roller 91 heats the toner image transferred to the recording paper S when the recording paper S passes between the fixing roller 91 and the pressure roller 92. Therefore, the ultraviolet phase transition material irradiated and irradiated with ultraviolet light by the first irradiation unit 40a and the third irradiation unit 40c can be solidified by heating. As a result, the fixability of the toner image to the recording paper S can be further improved.
When images are formed on both sides of the recording paper S, the recording paper S that has been subjected to the pressure-bonding process is transported to the paper reversing unit 24 before the paper discharge unit 14 and is discharged with the front and back reversed, or the front and back are reversed. The recording sheet S is conveyed again to the image forming unit 10.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

[Production of Toner 1]
[Production of toner base particles]
The toner base particles were prepared as follows.

(Preparation of resin particle dispersion 1)
201 parts by mass of styrene, 117 parts by mass of butyl acrylate and 18.3 parts by mass of methacrylic acid were mixed, and this monomer mixture was heated to 80 ° C. while stirring, and 172 parts by mass of behenyl behenate was gradually added and dissolved. did.
Next, a surfactant aqueous solution obtained by dissolving 3 parts by mass of the anionic surfactant “dodecylbenzenesulfonic acid” in 1182 parts by mass of pure water is heated to 80 ° C., the monomer solution is added, and high-speed stirring is performed. A monomer dispersion was prepared.

Next, 867.5 parts by mass of pure water was put into a polymerization apparatus equipped with a stirrer, a cooling pipe, a temperature sensor, and a nitrogen introduction pipe, and the internal temperature was set to 80 ° C. while stirring under a nitrogen stream. The monomer dispersion was charged into this polymerization apparatus, and a polymerization initiator aqueous solution in which 8.55 parts by mass of potassium persulfate was dissolved in 162.5 parts by mass of pure water was added.
After adding the polymerization initiator aqueous solution, 5.2 parts by mass of n-octyl mercaptan was added over 35 minutes, and polymerization was further performed at 80 ° C. for 2 hours. Next, an aqueous polymerization initiator solution in which 9.96 parts by mass of potassium persulfate was dissolved in 189.3 parts by mass of pure water was added, and 366.1 parts by mass of styrene, 179.1 parts by mass of butyl acrylate, 7-n-octyl mercaptan 7 The monomer solution mixed with 2 parts by mass was added dropwise over 1 hour. After the monomer solution was dropped, the polymerization treatment was continued for 2 hours, and then cooled to room temperature to prepare “resin particle dispersion 1”.

(Preparation of resin particle dispersion 1 for shell)
After adding 2948 parts by mass of pure water and 1 part by mass of the anionic surfactant “dodecylbenzenesulfonic acid” to a reactor equipped with a stirrer, a cooling tube, a nitrogen introduction tube, and a temperature sensor, Warm to 80 ° C under. Next, 520 parts by mass of styrene, 184 parts by mass of butyl acrylate, 96 parts by mass of methacrylic acid, 22.1 parts by mass of n-octyl mercaptan, and 10.2 parts by mass of potassium persulfate are added to 218 parts by mass of pure water. A dissolved polymerization initiator aqueous solution was prepared. After the polymerization initiator aqueous solution is charged into the reactor, the monomer mixture is added dropwise over 3 hours, and further polymerized for 1 hour, and then cooled to room temperature to prepare “resin particle dispersion 1 for shell”. did. The weight average molecular weight of the resin particles for shell was 13200. When the particle diameter of the resin particles for shells in “Shell resin particle dispersion 1” was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average particle diameter was 82 nm. Met.

(Preparation of carbon black dispersion)
11.5 parts by mass of sodium n-dodecyl sulfate is dissolved in 1600 parts by mass of pure water, 25 parts by mass of carbon black “Mogal L” is gradually added, and then “Claremix W Motion CLM-0.8 (M "Manufactured by Technic Co., Ltd.") was used to prepare a "carbon black dispersion" having a median diameter of 160 nm on a number basis.

(Preparation of UV phase change material dispersion 1)
80 parts by mass of dichloromethane and 20 parts by mass of UV phase change material 1 (Tokyo Kasei Kogyo Co., Ltd.) shown below as compound B were mixed and stirred while heating at 50 ° C., and “UV phase change material in which UV phase change material 1 was dissolved” Liquid 1 ”was obtained. A mixture of 99.5 parts by mass of distilled water warmed to 50 ° C. and 0.5 part of a 20% aqueous sodium dodecylbenzenesulfonate solution is added to 100 parts by mass of “UV phase change material liquid 1”, and then a homogenizer equipped with a shaft. Was stirred and emulsified at 16000 rpm for 20 minutes to obtain "Ultraviolet phase transition material emulsion 1".

  Then, the “ultraviolet phase transition material emulsion 1” was put into a separable flask, and the organic solvent was removed by heating and stirring at 40 ° C. for 90 minutes while feeding nitrogen into the gas phase. Dispersion 1 ”was obtained. The solid content concentration of the “ultraviolet phase change material dispersion liquid 1” was 11.0%. When the particle size of the ultraviolet phase change material fine particles in the “ultraviolet phase change material dispersion liquid 1” was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average particle size was 265 nm. Met.

  In compound B, R is a functional group represented by the following chemical formula C.

(Preparation of toner base particles 1)
The “resin particle dispersion 1” prepared above is 360 parts by mass in terms of solids, the “ultraviolet phase transition material dispersion 1” is 180 parts by mass in terms of solids, 900 parts by mass of ion-exchanged water, and the “carbon black dispersion” 70 parts by mass of “liquid” in terms of solid content was charged into a reaction apparatus equipped with a stirrer, a temperature sensor, and a cooling pipe. The temperature in the container was kept at 30 ° C., and the pH was adjusted to 10 by adding a 5 mol / liter sodium hydroxide aqueous solution.
Next, an aqueous solution in which 2 parts by mass of magnesium chloride hexahydrate is dissolved in 1000 parts by mass of ion-exchanged water is dropped over 10 minutes with stirring, and then the temperature is raised to 75 ° C. to aggregate and fuse the particles. I let you. The “Coulter Counter 3 (manufactured by Beckman Coulter)” was used as it was, and heating and stirring were continued until the median diameter (D50) on a volume basis became 6.5 μm.

When the median diameter (D50) on the volume basis reaches 6.5 μm, “shell resin particle dispersion 1” is 210 parts by mass in terms of solids, and “ultraviolet phase transition material dispersion 1” in terms of solids. 100 parts by mass was added, and stirring was performed for 1 hour to fuse the resin particles for shell and the fine particles of the ultraviolet phase transition material to the surface. Further, stirring is continued for 30 minutes to completely form the shell, and then an aqueous sodium chloride solution in which 40 parts by mass of sodium chloride is dissolved in 500 parts by mass of ion-exchanged water is added, and the internal temperature is raised to 78 ° C. Stirring was continued for 1 hour and then cooled to room temperature (25 ° C.) to form particles. The produced particles were repeatedly washed with ion-exchanged water and then dried with warm air at 35 ° C. to produce “toner base particles 1”.
The volume-based median diameter (D50) of the obtained “toner base particles 1” was measured using “Coulter Counter 3 (manufactured by Beckman Coulter)” to be 7.0 μm.

(Addition of external additives)
1.0 part by mass of hexamethylsilazane-treated silica (number average primary particle size 12 nm, hydrophobicity 68) and n-octylsilane-treated titanium dioxide (number average primary) with respect to 100 parts by mass of “toner base particle 1” By adding an external additive consisting of 0.3 parts by mass with a particle size of 20 nm and a hydrophobization degree of 63), and adding the external additive with “Henschel mixer” (manufactured by Mitsui Miike Mining Co., Ltd.), black “Toner 1” is obtained. Produced.
The external addition treatment using a Henschel mixer was performed under the conditions of a peripheral speed of a stirring blade of 35 m / second, a treatment temperature of 35 ° C., and a treatment time of 15 minutes.

[Preparation of Developer 1]
A ferrite carrier having a volume-based median diameter of 60 μm and coated with silicone resin is mixed with “toner 1” using a V-shaped mixer so that the toner concentration becomes 6% by mass. Was made.

[Preparation of Photoreceptor 1]
(Preparation of conductive support)
The surface of a drum-like aluminum support (outer diameter 100 mm, length 360 mm) was cut to produce a conductive support having a surface roughness Rz = 1.5 (μm).

(Formation of intermediate layer)
Using a sand mill with the following raw materials as a disperser, batch dispersion was performed for 10 hours to prepare a coating solution for forming an intermediate layer.
Binder resin: Polyamide resin “X1010” (manufactured by Daicel-Evonik) 1 part by mass Solvent: 20 parts by mass of ethanol Metal oxide fine particles: Titanium oxide fine particles “SMT500SAS” having a number average primary particle size of 0.035 μm (Taika) 1.1 parts by mass This intermediate layer forming coating solution is applied on the conductive support by a dip coating method to form a coating film, and this coating film is dried at 110 ° C. for 20 minutes to obtain a layer thickness. A 2 μm intermediate layer was formed.

(Formation of charge generation layer)
Dispersion was carried out for 10 hours using a sand mill using the following raw materials as a disperser to prepare a coating solution for forming a charge generation layer.
Charge generation substance: 20 parts by mass of titanyl phthalocyanine pigment (having a maximum diffraction peak at a position of 5 at least 27.3 ° by Cu-Kα characteristic X-ray diffraction spectrum measurement) Binder resin: Polyvinyl butyral resin “# 6000-C 10 parts by mass (manufactured by Denki Kagaku Kogyo Co., Ltd.) Solvent: 700 parts by mass of t-butyl acetate Solvent: 300 parts by mass of 4-methoxy-4-methyl-2-pentanone This charge generation layer is formed on the intermediate layer. The coating solution was applied by dip coating to form a coating film, and a charge generation layer having a layer thickness of 0.3 μm was formed.

(Formation of charge transport layer)
The following raw materials were mixed and dissolved to prepare a charge transport layer forming coating solution.
Charge transport material: 150 parts by mass of the compound shown in the following compound A Binder resin: 300 parts by mass of polycarbonate resin “Z300” (Mitsubishi Gas Chemical Co., Ltd.) Solvent: Toluene / tetrahydrofuran = 1/9 vol% 2000 parts by mass Inhibitor: “Irganox 1010” (manufactured by BASF Japan) 6 parts by mass Leveling agent: Silicone oil “KF-54” (manufactured by Shin-Etsu Chemical) 1 part by mass On the charge generation layer, this coating solution for forming a charge transport layer Was applied by a dip coating method to form a coating film, and this coating film was dried at 120 ° C. for 70 minutes to form a charge transport layer having a layer thickness of 20 μm.

(Formation of protective layer)
The following polymerizable compound, solvent and metal oxide fine particles were dispersed for 10 hours using a sand mill as a disperser under light shielding, then the following photopolymerization initiator was added, mixed under light shielding, stirred and dissolved, A coating solution for forming a protective layer was prepared.
Polymerizable compound: trimethylol propane trimethacrylate 100 parts by mass Solvent: sec-butanol 315 parts by weight Solvent: Tetrahydrofuran 15 parts by mass metal oxide fine particles: surface treatment agent _{(CH 2 = C (CH 3} ) COO (CH ₂ ) 150 parts by mass of tin oxide fine particles having a number average primary particle size of 20 nm and surface-treated with ₂ Si (OCH ₃ ) ₃ ) Photopolymerization initiator: 12 parts by mass of “IRGACURE819” (manufactured by BASF Japan) / radical scavenger : 7 parts by weight of “Sumilyzer GS” (Sumitomo Chemical Co., Ltd.)

The coating liquid for forming the protective layer was applied onto the charge transport layer using a circular slide hopper coating apparatus to form a coating film. After drying this coating film at room temperature for 20 minutes, a xenon lamp is used as a light source in a nitrogen stream with a nitrogen flow rate of 13.5 L / min, and the distance between the light source and the surface of the coating film is set to 5 mm. wavelength 365nm light at 4 kW (intensity: 4000 mW / cm ^2, the irradiation intensity of the light in the coating film: 1800mW / cm ²⁾ by a 18 seconds irradiation, the photosensitive member to form a protective layer having a thickness 3.5μm Produced.

The maximum height roughness Rz of the surface of the photoreceptor 1 was 0.039 μm when measured under the following measurement conditions using Surfcom 1400D (manufactured by Tokyo Seimitsu Co., Ltd.).
(Measurement condition)
Measuring device: Surfcom 1400D (manufactured by Tokyo Seimitsu Co., Ltd.)
Measurement mode: Roughness measurement Measurement length: 20.0 mm
Cut-off: 0.08mm (Gaussian)
Measurement speed: 0.15 mm / sec
Further, the universal hardness (HU) of the surface of the photoreceptor 1 was measured using a Fischer scope H100 (manufactured by Fischer Instruments), and was 225 (N / mm ² ).

[Production of photoconductors 2 to 6 and photoconductors 9 to 15]
The type of inorganic fine particles and the number average primary particle size (nm) were changed as shown in Table 1 below, and the amount of cured light was adjusted so that the universal hardness HU shown in Table 1 below was obtained, thereby forming a protective layer. Except for this, Photoconductors 2 to 6 and Photoconductors 9 to 15 were produced in the same manner as Photoconductor 1.

[Preparation of Photoreceptor 7]
Except that 5 parts by mass of TINUVIN P (BASF Japan) was added as an ultraviolet absorber, the amount of cured light was adjusted so as to be the universal hardness HU shown in Table 1 below, and a protective layer was formed. A photoconductor 7 was produced in the same manner as the photoconductor 1.

[Preparation of Photoreceptor 8]
Except that 5 parts by mass of TINUVIN 213 (manufactured by BASF Japan) was added as an ultraviolet absorber, the amount of cured light was adjusted so as to have the universal hardness HU shown in Table 1 below, and a protective layer was formed. In the same manner as in Example 1, a photoreceptor 8 was produced.

[Irradiation part]
In this example, an LED was used as the irradiation unit. In addition, the first irradiation unit to the fourth irradiation unit were installed in a monochrome image forming apparatus bizhub PRO 1250 (manufactured by Konica Minolta) so as to have the following configuration.

(Irradiation part configuration 1)
The first irradiation unit (ultraviolet LED) was arranged in the center of the developer conveyance path from “a supply position at which the developer is supplied to the photoconductor by the developing unit” to “a nip position between the photoconductor and the transfer roller”. The first irradiator was placed at the above position so as not to contact the photoreceptor.

(Irradiation part configuration 1 + 2)
In addition to the irradiation unit configuration 1, the second irradiation unit (visible LED) is arranged in the center of the developer conveyance path from the “nip position between the photosensitive member and the transfer roller” to the “blade contact position in the cleaning unit”. . The second irradiating unit was installed at the above position so as not to contact the photoconductor.

(Irradiation part configuration 1 + 3)
In addition to the irradiation unit configuration 1, the third irradiation unit (ultraviolet LED) is arranged at the center of the developer conveyance path from the “nip position between the photoconductor and the transfer roller” to the “nip position between the fixing roller and the pressure roller”. Arranged. Note that the third irradiation unit was installed at the above position so as not to contact the surface of the sheet nipped between the photosensitive member and the transfer roller.

(Irradiation part configuration 1 + 4)
In addition to the irradiation unit configuration 1, the fourth irradiation unit (visible LED) is arranged at the following position.
When the distance of the developer transport path from the “position position of the third irradiation unit” to the “nip position between the fixing roller and the pressure roller” is D, the “nip position between the fixing roller and the pressure roller” and the fourth The separation distance from the irradiation unit was set to D × (½), and the fourth irradiation unit was arranged on the downstream side in the developer conveyance direction with respect to the “nip position between the fixing roller and the pressure roller”. Note that the fourth irradiation unit was arranged at the above position so as not to contact the surface of the sheet nipped between the photosensitive member and the transfer roller.

[Production of Image Forming Apparatuses 1-14 and 31-34]
Developer 1 is mounted on a monochrome image forming apparatus bizhub PRO 1250 (manufactured by Konica Minolta Co., Ltd.), and photosensitive members 1 to 15 and irradiation unit configurations 1 to 4 are mounted as shown in Table 1 below to form an image. The apparatuses 1 to 14 and the image forming apparatuses 31 to 34 were used.

In the image forming apparatuses 1 to 8, the image forming apparatuses 12 to 14, and the image forming apparatuses 31 to 34 on which the irradiation unit configuration 1 is mounted, the wavelength of ultraviolet light emitted from the first irradiation unit (ultraviolet LED) is “365”. The irradiation amount of the ultraviolet light to the toner image by the first irradiation unit was “2.0” J / cm ² .

In the image forming apparatus 9 in which the irradiation unit configuration 2 is mounted, the wavelength of the ultraviolet light emitted from the first irradiation unit (ultraviolet LED) is “365” nm, and the amount of ultraviolet light applied to the toner image by the first irradiation unit Was “2.0” J / cm ² . In the image forming apparatus 9, the wavelength of visible light emitted from the second irradiation unit (visible LED) is “505” nm, and the amount of visible light irradiated to the developer by the second irradiation unit is “5.0”. J / cm ² .

In the image forming apparatus 10 in which the irradiation unit configuration 3 is mounted, the wavelength of the ultraviolet light emitted from the first irradiation unit (ultraviolet LED) is “365” nm, and the amount of ultraviolet light applied to the toner image by the first irradiation unit. Was “2.0” J / cm ² . In the image forming apparatus 10, the wavelength of the ultraviolet light emitted from the third irradiation unit (ultraviolet LED) is “365” nm, and the irradiation amount of the ultraviolet light to the toner image by the third irradiation unit is “5.0” J / Cm ² .

In the image forming apparatus 11 in which the irradiation unit configuration 4 is mounted, the wavelength of the ultraviolet light emitted from the first irradiation unit (ultraviolet LED) is “365” nm, and the amount of ultraviolet light applied to the toner image by the first irradiation unit Was “2.0” J / cm ² . In the image forming apparatus 11, the wavelength of visible light emitted from the fourth irradiation unit (visible LED) is “505” nm, and the amount of visible light irradiated to the developed image agent by the fourth irradiation unit is “5.0”. "had a J / cm ^2.

[Evaluation]
As shown in Table 1, with the image forming apparatuses 1 to 14 and the image forming apparatuses 31 to 34 in which the photosensitive members 1 to 15 and the irradiation units 1 to 4 are set, the fixation of the toner on the photosensitive member and the image flow are evaluated. The image formation was performed as follows.
When the amount of toner supplied to the photoconductor in the developing unit is 4 g / m ² , transfer conditions are adjusted so that the amount of toner transferred to the paper is 3.2 g / m ^2, and the transfer condition is 20 ° C., 50% RH. Then, after printing 1 million A4 images with a printing rate of 5% on neutral paper, the following evaluation was performed.

[Fixing of toner on the photoreceptor]
A strip-shaped solid image (relative reflection density of Macbeth densitometer is 2.0 (maximum value)) at the center of 1000 A4 sheets of neutral paper under an environment of 30 ° C and 80% RH. Formed.
The presence or absence of white spots in the solid portion of the paper was visually evaluated according to the following evaluation criteria.
A: No white spots occur (good)
B: White spots occur between 601 and 1000 (practical problem)
C: White spots occur between 301 and 600 (practical problem)
D: Occurrence of white spots between 0 and 300 (practical problem)

[Image Flow]
In an environment of temperature 30 ° C. and relative humidity 80% RH, an image with a Bk (black) printing rate of 5.0% was formed on 1000 sheets of A4 size neutral paper. The main power was turned off. After 12 hours, the main power supply was turned on again, and immediately after printing was possible, a halftone image (relative reflection density measured with a Macbeth densitometer was 0.4 (maximum value was 2) on the entire surface of neutral paper of A3 size. 0.0) image) and a grid image having a line width of 6 dots.

The state of the image on the paper was visually observed, and the rank was evaluated according to the following evaluation criteria.
A: Neither halftone image nor lattice image is blurred, and no image flow occurs. B: Only a halftone image has a strip-shaped density drop which is long in the width direction (photoconductor rotation axis direction). However, there is no problem in practical use. C: There is a problem in practical use because of image loss such as loss of lattice image due to image blur and line width narrowing.

As shown in Table 1, the image forming apparatus of the present invention is an image forming apparatus in which a developer containing a compound that undergoes phase transition by light absorption is used. The image forming apparatus irradiates a toner image on a photoreceptor with light, and In a method of directly transferring a toner image onto a sheet, a photoconductor having a maximum surface roughness Rz of 0.060 μm or less and a universal hardness HU in a range of 220 N / mm ² or more and 300 N / mm ² or less. Provided. As a result, it was found that even after the image formation was performed continuously for 1 million sheets, the sticking of the transfer residual toner to the photoconductor was effectively suppressed, and the image defects could be suppressed over a long period of time.

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging device 3 Exposure device 4 Development part 5 Transfer part 6 Static elimination part 7 Paper conveyance system 8 Cleaning part 9 Crimp part 10 Image formation part 11 Paper feed part 12 Carry roller 13 Conveyor belt 14 Paper discharge part 15 Manual paper feed Part 16 Tray 17 Thermohygrometer (Acquisition part)
20 image processing unit 24 sheet reversing unit 31 conductive support 32 intermediate layer 33 photosensitive layer 33a charge generation layer 33b charge transport layer 34 protective layer 40 irradiation unit 40a first irradiation unit 40b second irradiation unit 40c third irradiation unit 40d first 4 Irradiation unit 50 Transfer roller 71 Image reading device 72 Automatic document feeder 85 Blade 90 Control unit 91 Fixing roller 92 Pressure roller 100 Image forming apparatus d Document S Recording paper

Claims (6)

An image forming apparatus using a developer including toner particles containing a compound that undergoes phase transition by light absorption,
A photoreceptor on which an electrostatic latent image is formed;
A developing unit that develops the electrostatic latent image formed on the photoreceptor with the developer to form a toner image;
A first irradiation unit that irradiates the toner image on the photosensitive member with ultraviolet light having a wavelength of 300 nm or more and less than 400 nm;
A transfer unit that transfers the toner image irradiated with ultraviolet light by the first irradiation unit to a recording medium;
With
The photoreceptor has a maximum surface roughness Rz of 0.020 to 0.060 μm and a universal hardness HU in a range of 220 N / mm ^{2 to} 240 N / mm ^2. Image forming apparatus. The photoreceptor includes a protective layer as an outermost layer,
The image forming apparatus according to claim 1, wherein the protective layer contains inorganic fine particles.   The image forming apparatus according to claim 1, wherein the protective layer of the photoreceptor contains an ultraviolet absorber.   The second irradiation unit that irradiates visible light having a wavelength of 400 nm or more and 800 nm or less to the developer on the photosensitive member irradiated with ultraviolet light by the first irradiation unit. The image forming apparatus according to claim 3.   5. The apparatus according to claim 1, further comprising a third irradiation unit configured to irradiate the toner image transferred to the recording medium with ultraviolet light having a wavelength of 300 nm or more and less than 400 nm. The image forming apparatus described in 1.   6. The fourth irradiation unit according to claim 1, further comprising a fourth irradiation unit configured to irradiate the toner image transferred to the recording medium with visible light having a wavelength of 400 nm or more and 800 nm or less. The image forming apparatus described in 1.