JP2014202860A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that includes an imaging device using a clear toner, and can suppress a reduction in image quality due to voids and suppress a reduction in the life of an image carrier so as to contribute to a reduction in running costs.SOLUTION: An imaging device 120T using a clear toner includes a photoreceptor drum 122T having the elastic power represented by the following formula larger than that of photoreceptor drums of imaging devices 120C, 120M, 120Y, and 120K using a chromatic toner. Elastic power(%)=[workload of elastic deformation/(workload of plastic deformation+workload of elastic deformation)]×100.

Description

The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, a plotter, and a multifunction machine provided with at least one of them.
More specifically, the present invention relates to an image forming apparatus that can use clear toner (transparent toner) for the purpose of providing gloss in addition to normal process colors.

Some recent color laser printers and color laser complex machines can use toners other than yellow (Y), magenta (M), cyan (C), and black (K) process colors.
One of them is a clear toner called transparent toner, colorless toner, achromatic toner, or no-pigment toner.
A user can generate printed matter with high added value by using clear toner effectively.

For example, there has been proposed an image forming apparatus that performs gloss adjustment by overlaying clear toner on a color printed matter (full surface printing or partial printing) (overall coating or partial coating).
The entire surface coat or partial coat using the clear toner can give gloss to the entire surface of the paper or a part of the paper.
At the same time, it can be used for the purpose of preventing color transfer due to friction of the image surface and protecting the image.

Since clear toner that imparts high gloss is loaded on the entire surface or partially, the image area ratio of clear toner is considerably high, and it is used quite differently from C, M, Y, and K process toners (colored toners). It becomes.
The toner peripheral device is designed under optimum conditions according to how the process toner is used.
For this reason, when an image with a high image area ratio is continuously output, there is not much room for so-called “white spots” caused by the silica (additive) in the toner sticking into the photoreceptor. The reason will be described later.

When outputting an image, the electrostatic latent image formed on the photoreceptor is developed as a toner image with toner based on the image data, and the toner image is transferred from the photoreceptor to an intermediate transfer member or a recording medium.
However, the transfer residual toner remaining on the surface of the photoconductor after the transfer enters a cleaning device that cleans the surface of the photoconductor after the transfer.
Not all the transfer residual toner is cleaned by the cleaning device, but partially passes through the cleaning device.
When passing through the cleaning device, the silica as a toner additive pierces the photoreceptor and causes white spots.
In order to prevent white spots, Patent Documents 1 and 2 disclose a configuration in which a protective agent is applied to protect the surface of the photoreceptor.

Patent Document 3 discloses a method of automatically discharging and replenishing a carrier together with toner in an image forming method using colored toner and transparent toner in a two-component development system.
In this method, the weight ratio of the replenishment developer carrier in the transparent toner is set higher than the weight ratio of the replenishment developer carrier in the color toner.
As a result, it is possible to solve the problem of carrier deterioration due to accumulation of toner external additives (attachment to and release from the carrier surface, etc.).

Generally, clear toner is used for obtaining high gloss and protecting the image surface.
In any case, the main use is to cover the entire surface of the image or the area in the image where the desired effect is desired, not with halftone dots, with clear toner.
For this reason, in image formation using clear toner, the image area ratio is higher than that of general colored toner.
When there are many images with a high image area ratio, the amount of untransferred toner increases and the amount of silica is also large, so that white spots caused by silica sticking are easily accelerated.
Therefore, in an image forming apparatus using clear toner, the piercing of silica into the photosensitive member is accelerated more than that using colored toner.

When the transfer residual toner increases, the protective effect of the protective agent is weakened, and the piercing of silica into the photoconductor may be accelerated.
The piercing of silica into the photoconductor is a problem of white spots in terms of image quality, which also means a reduction in the life of the photoconductor.
In other words, when white spots are generated, if this is not improved, it is necessary to replace the photoconductor. In the image forming apparatus using clear toner, the life of the photoconductor is longer than that of the image forming apparatus using colored toner. Becomes shorter.

  The present invention was devised in view of such a current situation, and in a configuration having an image forming device using clear toner, it is possible to suppress a decrease in image quality due to white spots and to suppress a decrease in the life of the image carrier, The main object of the present invention is to provide an image forming apparatus that can contribute to a reduction in running cost.

In general, a photoreceptor using a UV curable resin (ultraviolet curable resin) for the surface layer increases the UV irradiation intensity and time in order to increase the elastic power.
In this case, as a side effect, the electrical characteristics of the photosensitive member tend to deteriorate, and the background potential increases with time.
This is the reason why there is no margin for “white spots”, in other words, the reason why the elastic power cannot be increased.

However, in the case of clear toner image formation, solid image output is almost all and halftone accuracy is not required. Therefore, there is room for electrical characteristics, and there are no side effects in the direction of increasing the elastic power.
There is no problem even if the elastic power of the photosensitive member is increased only in the image forming apparatus that forms a clear image, and it is possible to prevent the silica from being pierced and to increase the margin of white spots.
The present invention has been made paying attention to this point.

In other words, in order to achieve the above object, the present invention includes an image forming device using colored toner and an image forming device using clear toner. Each image forming device includes a static image forming device based on image information. An image bearing member on which an electrostatic latent image is formed is provided. The electrostatic latent image formed on each image bearing member is developed with a corresponding color toner, and each color toner image is finally superimposed on a recording medium. In the image forming apparatus for transferring the image, the image carrier of the image forming apparatus using the clear toner is represented by the following equation about the surface of the image carrier of the image forming apparatus using the colored toner. It is characterized by a high elastic power.
Elastic work rate (%) = {Work of elastic deformation / (Work of plastic deformation + Work of elastic deformation)} × 100

  According to the present invention, in a configuration having an image forming device using clear toner, it is possible to suppress a decrease in image quality due to white spots, to suppress a decrease in the life of the image carrier, and to contribute to a decrease in running cost.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. It is a control block diagram. It is an enlarged view of an image forming unit. It is a schematic block diagram which shows the manufacturing apparatus of an electrophotographic photoreceptor. It is a characteristic view which shows the permeability | transmittance of a filter. It is a figure for demonstrating the measuring method of an elastic power. It is a characteristic view which shows the relationship between elastic work rate and irradiation intensity. It is a characteristic view which shows the relationship between an elastic work rate and irradiation time.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, the overall configuration of the image forming apparatus according to the present embodiment and the configuration of the control unit will be described with reference to FIGS. 1 and 2.
The image forming apparatus 1 forms an image by fixing a toner image on a sheet as an example of a recording medium.
As shown in FIG. 1, the image forming apparatus 1 includes a control unit 10, an image reading unit 11, an image forming unit 12, a paper feeding unit 13, a transfer unit 14, a fixing unit 15, a paper discharge unit 16, and a display / operation unit. 17 etc.

As illustrated in FIG. 2, the control unit 10 includes a CPU (Central Processing Unit) 1011, a main memory (MEM-P) 1012, and a north bridge (NB) 1013.
Further, the control unit 10 includes a south bridge (SB) 1014 and an AGP (Accelerated Graphics Port) bus 1015.
In addition, the control unit 10 includes an application specific integrated circuit (ASIC) 1016, a local memory (MEM-C) 1017, and a hard disk (HD) 1018.
The control unit 10 includes an HDD (Hard Disk Drive) 1019 and a network I / F 102.

The CPU 1011 processes and calculates data according to a program stored in the main memory 1012, and operates the image reading unit 11, the image forming unit 12, the paper feeding unit 13, the transfer unit 14, the fixing unit 15, and the paper discharging unit 16. Or to control.
The main memory 1012 is a storage area of the control unit 10, and includes a ROM (Read Only Memory) 1012a and a RAM (Random Access Memory) 1012b.
The ROM 1012a is a memory for storing programs and data for realizing the functions of the control unit 10.
The program stored in the ROM 1012a is recorded in a computer-readable recording medium such as a CD-ROM, FD, CD-R, or DVD as a file in an installable or executable format and provided. May be.
The RAM 1012b is used as a memory for drawing during development of programs and data and memory printing.

The NB 1013 is a bridge for connecting the CPU 1011, the MEM-P 1012, the SB 1014, and the AGP bus 1015.
The SB 1014 is a bridge for connecting the NB 1013 to a PCI device and peripheral devices.
The AGP bus 1015 is a bus interface for a graphics accelerator card that has been proposed to speed up graphic processing.
The ASIC 1016 includes a PCI target, an AGP master, and an arbiter (ARB) that forms the core of the ASIC 1016.
The ASIC 1016 includes a memory controller that controls the MEM-C 1017, and a plurality of DMACs (Direct Memory Access Controllers) that rotate image data using hardware logic.

The ASIC 1016 is connected to a USB (Universal Serial Bus) interface via a PCI bus.
The ASIC 1016 is connected to an interface of IEEE 1394 (Institut of Electrical and Electronics Engineers 1394).
The MEM-C 1017 is a local memory used as a copy image buffer and a code buffer.

The HD 1018 is a storage for accumulating image data, accumulating font data used during printing, and accumulating forms.
The HDD 1019 controls reading or writing of data with respect to the HD 1018 according to the control of the CPU 1011.
The network I / F 102 transmits / receives information to / from an external device such as an information processing apparatus via a communication network.

The image reading unit 11 generates image information by optically reading an image written on a sheet.
Specifically, the image information is read by applying light to a sheet and receiving the reflected light by a reading sensor such as a CCD (Charge Coupled Devices) or a CIS (Contact Image Sensor).
The image information is information representing an image to be formed on a recording medium such as paper, and uses electrical color separation image signals indicating red (R), green (G), and blue (B) colors. It is shown.
As shown in FIG. 1, the image reading unit 11 includes a contact glass 111, a reading sensor 112, and the like.

The contact glass 111 is for placing a sheet on which an image is written.
The reading sensor 112 reads image information of an image described on a sheet placed on the contact glass 111.

The image forming unit 12 attaches toner to the surface of the intermediate transfer belt 143 of the transfer unit 14 based on the image information read by the image reading unit 11 or the image information received by the network I / F 102 to generate an image (toner Image).
The image forming unit 12 includes an image forming unit 120C that forms a toner image using a developer having cyan (C) color toner, and an image forming unit 120M that forms a toner image using magenta (M) toner. An image forming unit 120Y that forms a toner image using yellow (Y) toner, an image forming unit 120K that forms a toner image using black (K) toner, and a clear (T) toner. And an image forming unit 120T that forms a toner image using the same.
The image forming unit means an image forming device.

  As will be described later, the image forming apparatus 1 develops the electrostatic latent image formed on each photosensitive drum with the corresponding color toner, and finally puts the toner image of each color on the recording medium. It has a configuration for transferring.

Hereinafter, one or more of the C color toner, the M color toner, the Y color toner, and the K color toner is referred to as a colored toner.
The image forming apparatus using clear toner is arranged so as to be positioned at the top of the toner image transfer order of each image forming apparatus, including the image forming apparatus using colored toner.
Each colored toner is a resin particle having a charging property containing a coloring material such as a pigment or a dye.
Further, the clear toner is a colorless and transparent toner, and is a resin particle configured so that the colored toner can be visually recognized when attached to the colored toner attached to the recording medium.

The clear toner is resin particles that can be visually recognized when attached to the recording medium.
The clear toner is produced, for example, by externally adding silicon dioxide (SiO ₂ ) or titanium dioxide (TiO ₂ ) to a low molecular weight polyester resin.
Note that the clear toner may contain a coloring material as long as the amount is such that the recording medium or the colored toner attached on the recording medium can be visually recognized.

Hereinafter, an arbitrary image forming unit among the image forming unit 120C, the image forming unit 120M, the image forming unit 120Y, the image forming unit 120K, and the image forming unit 120T is referred to as an “image forming unit 120”.
The image forming unit 120C includes a toner supply unit 121C, a photosensitive drum (hereinafter also simply referred to as “photosensitive member”) 122C, a charging unit 123C, an exposure unit 124C, a developing unit 125C, a charge eliminating unit 126C, and a cleaning unit 127C. Yes.
The toner supply unit 121C stores C-color toner, and supplies C-color toner to the development unit 125C.
The toner stored in the toner supply unit 121C is supplied to the developing unit 125C by a predetermined amount by driving the conveying screw in the toner supply unit 121C.
The surface of the photosensitive drum 122C is uniformly charged by the charging unit 123C, and an electrostatic latent image is formed on the surface by the exposure unit 124C based on the image information received from the control unit 10.

On the surface of the photosensitive drum 122C, a toner image is formed by the developing unit 125C attaching toner to the surface on which the electrostatic latent image is formed.
The photosensitive drum 122C is provided so as to be in contact with the intermediate transfer belt 143, and is provided to rotate in the same direction as the moving direction of the intermediate transfer belt 143 at a contact point with the intermediate transfer belt 143.
The charging unit 123C uniformly charges the surface of the photosensitive drum 122C.
The exposure unit 124C irradiates the surface of the photosensitive drum 122C charged by the charging unit 123C with light based on the C halftone dot area ratio determined by the control unit 10 to form an electrostatic latent image.
The developing unit 125C develops the toner image by attaching the C-color toner stored in the developer storage unit 121C to the electrostatic latent image formed on the surface of the photosensitive drum 122C by the exposure unit 124C. Form.

The neutralization unit 126C neutralizes the surface of the photosensitive drum 122C after the image is transferred to the intermediate transfer belt 143.
The cleaning unit 127C removes the transfer residual toner remaining on the surface of the photosensitive drum 122C that has been neutralized by the neutralization unit 126C.

The image forming unit 120M includes a developer storage unit 121M, a photosensitive drum 122M, a charging unit 123M, an exposure unit 124M, a developing unit 125M, a charge removal unit 126M, and a cleaning unit 127M.
The developer storage unit 121M stores M-color toner.
The photosensitive drum 122M, the charging unit 123M, the exposure unit 124M, the development unit 125M, the charge removal unit 126M, and the cleaning unit 127M are the photosensitive drum 122C, the charge unit 123C, the exposure unit 124C, the development unit 125C, the discharge unit 126C, and the cleaning unit, respectively. Since the function is the same as that of 127C, the description thereof is omitted (the same applies to Y, K, and T).

The image forming unit 120Y includes a developer container 121Y, a photosensitive drum 122Y, a charging unit 123Y, an exposure unit 124Y, a developing unit 125Y, a charge removal unit 126Y, and a cleaning unit 127Y.
The developer storage unit 121Y stores Y toner.
The image forming unit 120K includes a developer container 121K, a photosensitive drum 122K, a charging unit 123K, an exposure unit 124K, a developing unit 125K, a charge removal unit 126K, and a cleaning unit 127K.
The developer storage unit 121K stores K-color toner.

The image forming unit 120T includes a developer storage unit 121T, a photosensitive drum 122T, a charging unit 123T, an exposure unit 124T, a developing unit 125T, a charge removal unit 126T, and a cleaning unit 127T.
The developer storage unit 121T stores clear toner.
Hereinafter, any developer accommodating portion among the developer accommodating portion 121C, the developer accommodating portion 121M, the developer accommodating portion 121Y, the developer accommodating portion 121K, and the developer accommodating portion 121T is referred to as “developer accommodating portion 121”. It expresses.
An arbitrary photosensitive drum among the photosensitive drum 122C, the photosensitive drum 122M, the photosensitive drum 122Y, the photosensitive drum 122K, and the photosensitive drum 122T is represented as “photosensitive drum 122”.
Any charging unit among the charging unit 123C, the charging unit 123M, the charging unit 123Y, the charging unit 123K, and the charging unit 123T is referred to as a “charging unit 123”.

An arbitrary exposure unit among the exposure unit 124C, the exposure unit 124M, the exposure unit 124Y, the exposure unit 124K, and the exposure unit 124T is referred to as an “exposure unit 124”.
An arbitrary developing unit among the developing unit 125C, the developing unit 125M, the developing unit 125Y, the developing unit 125K, and the developing unit 125T is represented as “developing unit 125”.
Any static elimination part among the static elimination part 126C, the static elimination part 126M, the static elimination part 126Y, the static elimination part 126K, and the static elimination part 126T is represented as "the static elimination part 126".
An arbitrary cleaning unit among the cleaning unit 127C, the cleaning unit 127M, the cleaning unit 127Y, the cleaning unit 127K, and the cleaning unit 127T is referred to as a “cleaning unit 127”.

The paper supply unit 13 supplies paper to the transfer unit 14. The paper feed unit 13 includes a paper storage unit 131, a paper feed roller 132, a paper feed belt 133, and a registration roller pair 134.
The paper storage unit 131 stores paper that is an example of a recording medium. The paper feed roller 132 is provided to rotate in order to move the paper stored in the paper storage unit 131 toward the paper supply belt.
The paper feed roller 132 provided in this way takes out the uppermost one of the stored paper one by one and places it on the paper feed belt.
The paper feed belt 133 conveys the paper taken out by the paper feed roller 132 to the transfer unit 14.
The registration roller pair 134 feeds out the sheet conveyed by the sheet feeding belt 133 at a timing when a portion where a toner image is formed on the intermediate transfer belt 143 described later reaches the transfer unit 14.

The transfer unit 14 transfers the image formed on the photosensitive drum 122 by the image forming unit 12 to the intermediate transfer belt 143 (primary transfer), and transfers the image transferred to the intermediate transfer belt 143 to the sheet (secondary transfer). )
The transfer unit 14 includes a drive roller 141, a driven roller 142, an intermediate transfer belt 143, primary transfer rollers 144C, 144M, 144Y, 144K, and 144T, a secondary transfer roller 145, and a secondary transfer counter roller 146.
The driving roller 141 spans the intermediate transfer belt 143 together with the driven roller 142.
As the driving roller 141 is driven and rotated, the intermediate transfer belt 143 that is being moved moves.

The intermediate transfer belt 143 moves while contacting the photosensitive drum 122 as the drive roller 141 rotates.
As the intermediate transfer belt 143 moves while being in contact with the photosensitive drum 122, the image formed on the photosensitive drum 122 is transferred to the surface of the intermediate transfer belt 143.

The primary transfer rollers 144C, 144M, 144Y, 144K, and 144T are arranged to face the photosensitive drums 122C, 122M, 122Y, 122K, and 122T, respectively, with the intermediate transfer belt 143 interposed therebetween.
The secondary transfer roller 145 rotates with the intermediate transfer belt 143 and the paper sandwiched between the secondary transfer counter roller 146.

The fixing unit 15 fixes the toner transferred to the sheet by the transfer unit 14.
Fixing refers to fusing the resin component of the toner to the paper by simultaneously applying heat and pressure to the toner.
By fixing the toner transferred to the paper by the transfer unit 14, the state of the toner on the paper becomes stable.
The fixing unit 15 includes a conveyance belt 151, a fixing belt 152, a fixing roller 153, a fixing belt conveyance roller 154, a fixing counter roller 155, and a heat generation unit 156.
The conveyance belt 151 conveys the sheet on which the toner is transferred by the transfer unit 14 toward the fixing roller 153 and the fixing counter roller 155.

The fixing belt 152 is stretched between the fixing roller 153 and the fixing belt conveying roller 154, and moves as the rollers rotate.
The fixing roller 153 sandwiches the sheet transported to the transport belt 151 between the fixing facing roller 155 disposed opposite to the sheet, and heats and pressurizes the sheet.
The fixing belt conveyance roller 154 hangs the fixing belt 152 together with the fixing roller 153, and moves the fixing belt 152 when the fixing belt conveyance roller 154 rotates.
The fixing facing roller 155 is installed facing the fixing roller 153, and sandwiches the conveyed paper between the fixing roller 153.
The heat generating unit 156 is installed inside the fixing roller 153 and generates heat, and heats the sheet via the fixing roller 153.

The paper discharge unit 16 discharges the paper on which the toner is fixed by the fixing unit 15 from the image forming apparatus 1, and includes a paper discharge belt 161, a paper discharge roller 162, a paper discharge port 163, and a paper storage unit 164. doing.
The paper discharge belt 161 conveys the paper fixed by the fixing unit 15 toward the paper discharge port 163.
The paper discharge roller 162 discharges the paper conveyed by the paper discharge belt 161 from the paper discharge port 163 and stores it in the paper storage unit 164. The paper storage unit 164 stores the paper discharged by the paper discharge roller 162.

The display / operation unit 17 includes a panel display unit 171 and an operation unit 172.
The panel display unit 171 displays setting values and selection screens. The panel display unit 171 is a touch panel or the like that receives input from the operator.
The operation unit 172 is operated by a user for input such as a numeric keypad for receiving various conditions relating to image formation and a start key for receiving a copy start instruction.

The high gloss clear toner in this embodiment has a storage elastic modulus G ′ (G prime) of 100 or less and a loss tangent tan δ (tangent delta) of 10 or more.
The clear toner is also called a transparent toner, a colorless toner, or a no-pigment toner, and basically refers to a toner prepared by removing a colored pigment from a colored toner.
Since the clear toner does not have a coloring pigment, the clear toner image obtained is transparent.
Since the gloss of the image creating portion changes like a varnish-coated image, a clear toner image is well known for use such as creating a clear toner image only at a location where it is desired to change the gloss.

A clear toner can be produced by any method such as pulverization or polymerization.
For example, a general method for producing a polymerized toner includes a resin prepolymer having a functional group, a resin such as styrene acryl or polyester, a colorant, and a toner material solution in which an additive is dispersed in an organic solvent. / Or an extension reaction.
In some cases, the physical property change of the toner base resin caused by removing the color pigment is compensated by other materials.
For example, a general method for producing a pulverized toner is to knead a resin, a colorant and other additives, and after cooling, coarsely pulverize, finely pulverize and classify.

The clear toner is usually white, which is the color of the resin, but the clear toner image after heat fixing is a transparent color.
Although it may be slightly cloudy depending on the fixing state, it is almost completely transparent.

The high gloss clear toner will be described in detail.
Image gloss obtained with a general toner including color and toner and a general electrophotographic apparatus is 60 degree gloss (represented as Gs (60)) and is about 60 to 70 at maximum.
In contrast, the gloss of a silver salt photograph is 90 or more in Gs (60), and the gloss of a general varnish image is 80 or more in Gs (60).
In other words, gloss cannot be obtained with a general electrophotographic apparatus like silver salt photographs and varnish images.
Therefore, a clear toner capable of obtaining gloss such as a silver salt photograph or a varnish image is defined as a high gloss clear toner, and details are described below.

In order to achieve the high gloss toner, it is necessary that the storage elastic modulus G ′ (G prime) is 100 or less and the loss tangent tan δ (tangent delta) is 10 or more at the set fixing temperature.
That is, the toner can be easily spread by controlling the viscoelasticity of the heat-melted toner as described above.
As a result, the base surface is likely to be covered with toner. Therefore, the spread toner covers the base surface, the surface is smoothed, and a high gloss image is easily obtained.
In order to control the viscoelasticity of the heat-melted toner as described above, one of means is to select a toner resin material.
However, such a toner resin material is a trade-off against deterioration of toner releasability during heating and pressure fixing.

Therefore, it is necessary to ensure the toner releasability by increasing the amount of the release agent or adding a fine particle material.
A method for measuring the storage elastic modulus G ′ and the loss tangent tan δ will be described.
Viscoelasticity is one of the indices for evaluating the mechanical properties of polymer materials that have both elasticity and viscosity.
Viscoelasticity detects stress from a material while applying a sinusoidal distortion to the material, and measures storage elastic modulus, loss elastic modulus, and loss tangent, which are indicators of dynamic viscoelasticity, from the distortion waveform and the stress waveform. To do.
The storage elastic modulus G ′ (G prime) of a material is defined as the ratio of elastic stress in phase with strain, and represents the ability of the material to store energy elastically, that is, the elastic property.

Similarly, the loss elastic modulus G ″ (gible double prime) is a phase ratio different from strain, and represents the ability of a material to release stress as heat, that is, a viscous property.
The ratio G ″ / G ′ of these two elastic moduli is defined as the loss tangent tan δ (tangent delta) and indicates the ratio of the viscous component to the elastic component of the material.
The above is a value obtained by shear measurement, and is expressed by shear modulus G. If it is a value obtained by stretching or bending measurement, it is expressed by stretch modulus E.

In many cases, the dynamic viscoelasticity measuring device DMA (Dynamic mechanical analysis) is used for the measurement.
DMA is a method for measuring the mechanical properties of a sample by applying a strain or stress that changes (vibrates) over time to the sample and measuring the stress or strain generated thereby.
The sample is placed on the measurement probe, heated by a heater or the like, and stress is applied to the sample from the load generation unit via the probe.
This stress is given as a sinusoidal force with a frequency set as one of the measurement conditions so that the strain amplitude of the sample is constant.
The amount of deformation (strain) of the sample caused by this sinusoidal force is detected by the displacement detector, and various viscoelastic amounts such as elastic modulus and viscosity are calculated from the stress applied to the sample and the detected strain, and the temperature or Output as a function of time.

From this measurement result, G ′, G ″ and tan δ can be calculated.
In the present invention, a HAAKE rheometer / viscosmeter RheoStress RS150 was used, and about 0.2 g of toner was pressure-molded (pressed 10 t) into a disk shape.
G ′ and tan δ were calculated by sandwiching them between disk-shaped measuring jigs, applying periodic strain to the sample in the temperature range of 120 to 200 ° C., and accurately measuring the generated stress.

The oilless high gloss clear toner will be described.
A toner having a G ′ (storage modulus) of 100 or less and a tan δ (loss tangent) of 10 or more at the set fixing temperature described in the present invention has high spreadability at the time of heat and pressure fixing, and the image has high gloss. However, there is a concern that the toner releasability may deteriorate during heating and pressure fixing.
In conventional existing toners, deterioration of toner releasability has been compensated by application of silicone oil or the like in a fixing device.
The high-gloss clear toner described in the present invention secures the toner releasability by increasing the amount of the release agent or adding a fine particle material, so that it is not necessary to apply silicone oil or the like in the fixing device.
That is, the high-gloss clear toner described in the present invention is different from conventional toners in that it can be used in a so-called oil-less fixing device that does not require the application of a release agent such as silicone oil to the fixing device.

FIG. 3 is a schematic diagram of the image forming apparatus (image forming unit) of FIG.
The image forming apparatus is an apparatus in which at least one of a cleaning unit (cleaning unit), a charging unit (charging unit), and a developing unit (developing unit) is integrated with the photosensitive member.
The charging unit 123 includes a charging roller 123a, a charging cleaner roller 123b, and a pressure spring that pressurizes them.
The surface of the photoconductor 122 is uniformly charged by the charging roller 123a.
As charging means, there are a scorotron system, a corotron system, a contact roller charging system using a medium resistance rubber roller, and a non-contact roller charging system, which are charging by a wire.
In this embodiment, a non-contact charging roller charging method is adopted.

The Scorotron method was previously used to charge the surface of a photoconductor to (-). However, ozone is generated during discharge, so from the viewpoint of placing importance on the environment, there are currently limited models. Used only in groups.
The corotron method charges the photosensitive member to (+) and generates less ozone, but is not commonly used.
Recently, since the unit price of a charging roller capable of suppressing the generation of ozone has been reduced, the roller charging method is the most common charging means.
For both the contact roller charging method and the non-contact roller charging method, there are a method of superimposing alternating current on direct current and a method of applying only direct current.

When alternating current is superimposed on direct current, high image quality can be obtained compared to direct current, but attention must be paid to the problem of photoconductor filming.
In addition, the constant current control of alternating current has the advantage that the surface potential is not affected by fluctuations in the resistance value of the charging roller due to environmental changes, but the cost of the high-voltage power supply increases and the sound of alternating high frequency is a problem. It is as.
When only a direct current is applied, a change in the resistance value of the charging roller due to the environmental change affects the surface potential with respect to the environmental change, and thus some means for correcting the applied voltage is required.

In the case of non-contact, if alternating current is controlled at a constant current, the image will be uneven due to the effect of gap fluctuation between the photoconductor and the charging roller. Therefore, the applied voltage is corrected in the same way as when only direct current is applied. Means are needed.
However, since it is non-contact, there is more room for contamination of the charging roller than the contact type.
As a correction method, there are a method of detecting the temperature in the vicinity of the charging roller and switching the applied voltage, a method of periodically detecting ground contamination on the photosensitive member and switching the applied voltage, and a method of determining the applied voltage based on a feedback current value. is there.
By taking these methods, the surface of the photoreceptor is charged to about -500V to -700V.
As a driving method, there are a method in which the photosensitive member is pressed against the photosensitive member and rotated by a frictional force, and a method in which a driving force is obtained from a photosensitive member gear or the like.
In the case of a low speed machine, the former method is often used, but in the machine that requires high speed and high image quality, the latter method is often used.

When the surface of the charging roller becomes dirty, the charging ability of the portion where the dirt is attached is reduced, and the photosensitive member cannot be charged to the target potential.
As a result, an abnormal image of defective charging appears.
In order to prevent this, a charging roller cleaner (cleaning roller) 123b is brought into contact.
The charging roller cleaner 123b includes a flocking roller in which fibers are electrostatically flocked on a metal shaft, and a melamine roller in which a melamine resin is disposed on the roller around the metal shaft. In most cases, a roller is used.
If slip occurs between the cleaning roller and the charging roller, the dirt is rubbed against the surface of the charging roller, and the generation of an abnormal image due to the dirt is accelerated.

With respect to the charging roller cleaner, the surface of the charging roller is removed by moving around the charging roller without being driven.
When the drive is applied, a slipping state is inevitably caused by the tolerance of the charging roller diameter and the diameter tolerance of the charging roller cleaner, and the life is shortened.
Ideally, it is desirable that the surface moving speed is the same at the contact portion between the charging roller and the cleaning roller without slipping.

In FIG. 3, symbol Lb indicates exposure light from the exposure unit 124.
In FIG. 3, the static elimination unit 126 is omitted.

The cleaning unit 127 includes a cleaning blade 127a, a waste toner collecting coil 127b, and the like.
The cleaning blade 127a is made of urethane rubber and is in contact with the surface of the photoreceptor in the counter direction.
The most commonly used method (cleaning blade method) is to scrape the residual toner after transfer at the edge of the cleaning blade 127a.
The toner scraped off by the cleaning blade is transported forward or rearward in the figure by a waste toner collecting coil and stored in a waste toner tank (not shown).
In color copiers, there is a problem of color mixing of waste toner, and generally it is not reused.

In order to protect the photoreceptor surface, a photoreceptor protectant (lubricant) may be applied to the photoreceptor surface.
This is performed to prevent photoconductor filming, to secure a cleaning function, to protect the photoconductor surface from charging AC, and to prevent wear of the photoconductor.
A protective agent coating device 128 is provided on the downstream side of the cleaning unit 127 in the photosensitive member moving direction (not shown in FIG. 1).
The protective agent applying device 128 includes a lubricant 128a, a brush roller 128b for applying the lubricant 128a on the photosensitive member, a pressure spring 128c for pressing the lubricant 128a toward the brush roller 128b, and the like.

The photoconductor protective agent is in pressure contact with the brush roller, and is gradually scraped by the rotation of the brush roller, and the shaved protective agent is applied to the surface of the photoconductor.
The lubricant applied on the photoreceptor is stretched into a thin layer by the application blade 129 disposed on the downstream side, and is fixed on the photoreceptor surface with a uniform thickness.

As the protective agent application means, a brush roller is most often used, and as the material, insulating PET, conductive PET, acrylic fiber, or the like is used.
In particular, conductive fibers are often used in order to avoid abnormal images due to the effect of frictional charging by the brush roller and the photoconductor.
Lubricant pressurization means include compression springs, weights, tension springs and cams, but compression springs are most often used in terms of balance of function, space, and cost. ing.
The photoconductor protective agent mainly contains a fatty acid metal salt and an inorganic lubricant. Depending on the amount of inorganic lubricant added, inorganic fine particles may be contained.

Examples of fatty acid metal salts include barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate, cadmium stearate, magnesium stearate, zinc stearate , Zinc oleate, magnesium oleate, iron oleate, cobalt oleate, copper oleate, lead oleate, manganese oleate, zinc palmitate, cobalt palmitate, lead palmitate, magnesium palmitate, aluminum palmitate, palmitate Calcium acid, lead caprylate, lead caprate, zinc linolenate, cobalt linolenate, calcium linolenate, zinc ricinoleate, cadmium ricinoleate and mixtures thereof However, the present invention is not limited to these.
Moreover, you may mix and use these. Among these, zinc stearate is most preferably used because it is particularly excellent in film formability on an image carrier.

An inorganic lubricant refers to a substance that cleaves and lubricates itself or causes internal slip.
Examples of this include, but are not limited to, mica, boron nitride, molybdenum disulfide, tungsten disulfide, talc, kaolin, montmorillonite, calcium fluoride, and graphite.
Among them, boron nitride has hexagonal mesh planes in which atoms are tightly combined, overlapping at a wide interval, and it is only the weak van der Waals force that connects the layers, so the layers are easily cleaved, Good lubricity and preferable.
In the present invention, it is preferable to use a powdery protective agent obtained by mixing these materials. If necessary, these powdery protective agents are molded into a bar shape by, for example, compression molding or melting and melt molding powder.
An inorganic fine particle refers to a particle that is sandwiched between objects and acts as a roller but does not cause internal slip or cleavage by the substance itself. The inorganic lubricant is prevented from filming on the photoreceptor.

Whether it can be added is determined by the amount of inorganic lubricant added.
Examples of this include metal oxides such as silica, copper oxide, zinc oxide, titanium oxide, alumina, zirconium oxide, indium oxide, antimony oxide, antimony-doped tin oxide, tin-doped indium oxide, tin fluoride, There are metal fluorides such as calcium fluoride and aluminum fluoride, potassium titanate and the like, but not limited thereto.
A plurality of these may be mixed.
Although details of the developing means (developing section) are not shown, it does not matter whether the developing means is a two-component developing device or a one-component developing device in the present invention.

In recent years, organic photoconductive materials have been widely used as materials used in electrophotographic photoreceptors because of their advantages such as high productivity and non-pollution.
In addition, in electrophotographic photoreceptors that are used repeatedly, surface wear is caused by direct electrical and mechanical external forces such as charging, exposure, development, transfer to an intermediate transfer body or paper, and cleaning treatment. In addition, durability against deterioration of electrical characteristics is also required.
In the present invention, in order to achieve these durability, it is preferable to provide a surface layer which is polymerized or crosslinked by ultraviolet irradiation and cured on the photosensitive layer of the electrophotographic photosensitive member.

The photoreceptor of the present embodiment is a laminate having at least a photosensitive layer and a surface layer (surface protective layer) in this order on a conductive support (cylindrical substrate).
The photosensitive layer may have a single layer structure or a multilayer structure as long as it has a charge generation function and a charge transport function.
In the case of a multi-layer structure, a function-separated layer (function-separated layered structure) is generally used for a charge generation layer having a charge generation function and a charge transport layer having a charge transport function.

In the case of adopting a function separation type laminated structure, the order in which the charge generation layer and the charge transport layer are laminated on the conductive support is not particularly defined.
However, when the charge generation layer is on the surface layer side, the charge generation layer is likely to be deteriorated by an acidic gas generated by a charger or the like.
Also, it is difficult to apply the charge generation layer without eroding the charge transport layer.
For these reasons, generally the charge generation layer is often laminated on the conductive support side.

As a cylindrical substrate, aluminum, copper, gold, silver, platinum, palladium, titanium, nickel-chromium, stainless steel, aluminum, copper, iron, zinc, nickel or other metal drum or sheet, paper, plastic or glass A metal such as copper-indium is deposited.
Alternatively, conductive metal oxides such as indium oxide and tin oxide are deposited, metal foil is laminated, or carbon black, indium oxide, tin oxide-antimony oxide powder, metal powder, copper iodide, etc. are bound. Disperse in resin and apply.
Known materials can be used, such as those formed into a drum shape after conducting a conductive treatment, but the present invention is not limited to these.

The photosensitive layer includes a charge generation layer and a charge transport layer.
Examples of the charge generation material contained in the charge generation layer include C.I. Pigment Blue 25 (Color Index CI 21180), C.I. Pigment Red 41 (CI 21200), C. I. Cic Red 52 (CI 45100), and C.I. Basic Red 3 (CI 45210). An azo pigment having a carbazole skeleton, an azo pigment having a distyrylbenzene skeleton, an azo pigment having a triphenylamine skeleton, an azo pigment having a dibenzothiophene skeleton, an azo pigment having an oxadiazole skeleton, an azo pigment having a fluorenone skeleton, Azo pigments such as azo pigments having a bisstilbene skeleton, azo pigments having a distyryloxadiazole skeleton, and azo pigments having a distyrylcarbazole skeleton; for example, CI Pigment Blue 16 (CI 7 100) and other phthalocyanine pigments; for example, Indigo pigments such as C-Ibat Brown (CI 73410) and C-Ibat Die (CI 73030); Argol Scarlet 5 (manufactured by Bayer), Induslens Scarlet R (manufactured by Bayer) Examples include perylene pigments, squary dyes, hexagonal Se powders, and the like.

These charge generation materials are pulverized and dispersed together with a solvent such as tetrahydrofuran, cyclohexanone, dioxane, or dichloroethane by a method such as a ball mill, an attritor, or a sand mill.
At this time, for example, polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, polyacrylamide, etc. are bound. It may be added as an agent.

Examples of the charge transport material include polycyclic aromatic compounds such as anthracene, pyrene, phenanthrene and coronene in the main chain or side chain, or indole, carbazole, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, thiadiazole, A compound having a nitrogen-containing cyclic compound such as triazole, a triphenylamine compound, a hydrazone compound, an α-phenylstilbene compound, or the like is used.
These charge transport materials are made of polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, Vinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, Prepare a charge transport layer forming solution by dissolving it in a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, etc. together with a thermoplastic or thermosetting resin such as phenol resin or alkyd resin. , Spray coating, and the drying after a pre-drying to form a charge transport layer.

The surface protective layer is an ultraviolet-cured layer formed by the electrophotographic photoreceptor manufacturing apparatus of the present invention, the polymer as the main component, a monomer that is a reaction diluent for adjusting the viscosity of the resin, and a photo-curing catalyst. It consists of a photopolymerization initiator having a role and additives such as an antioxidant.
Examples of the polymer include urethane acrylate, epoxy acrylate, and polyester acrylate.
As monomers, compounds having radical polymerizability such as compounds having 3 acryloyloxy groups and 3 hydrogen groups, compounds having 4 acryloyloxy groups and 2 hydrogen groups, trimethylolpropane triacrylate, etc. And a trifunctional or higher functional radical polymerizable compound having no charge transporting structure.
Examples of the photopolymerization initiator include benzophenone, Michler ketone, and benzoin butyl ether.

[Example]
In order to further clarify the effects of the present invention, examples are given below. In addition, these are only one aspect | mode of this invention, and the technical scope of this invention is not limited to these.
Example 1
With the composition shown below, coating solutions for the undercoat layer, the charge generation layer, and the charge transport layer were prepared, and each layer was formed by spray coating to prepare an electrophotographic photoreceptor.

(Formation of undercoat layer)
15 parts by weight of alkyd resin (Beccosol 1307-60-EL (Dainippon Ink Chemical Co., Ltd.)) and 10 parts by weight of melamine resin (Super Becamine G-821-60 (Dainippon Ink Chemical Co., Ltd.)) were added with 150 methyl ethyl ketone. Dissolved in parts by weight.
90 parts by weight of titanium oxide powder (Taipere CR-EL (manufactured by Ishihara Sangyo Co., Ltd.)) was added thereto and dispersed for 12 hours by a ball mill.
The obtained solution was taken out into a container and diluted with cyclohexanone so that the solid content was 25% by weight to obtain an undercoat layer coating solution.
Subsequently, the coating solution was spray-coated on the outer peripheral surface of the cylindrical substrate to form an undercoat layer having a film thickness of 6.3 μm.

(Formation of charge generation layer)
Next, 5 parts by weight of polyvinyl butyral resin (S-REC HL-S: manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 150 parts by weight of methyl ethyl ketone.
To this, 10 parts by weight of a trisazo pigment represented by the following structural formula (1) was added, dispersed for 48 hours with a ball mill, and further 210 parts by weight of cyclohexanone was added to carry out dispersion for 3 hours.
The resulting solution was taken out into a container and diluted with cyclohexanone so that the solid content was 1.5% by weight.

  The charge generation layer coating solution prepared as described above was spray-coated on the substrate on which the undercoat layer was formed, as in the case of the undercoat layer, to form a charge generation layer having a thickness of 0.2 μm.

(Formation of charge transport layer)
Next, bisphenol A polycarbonate resin 10 and 0.002 parts by weight of silicone oil (KF-50: manufactured by Shin-Etsu Chemical Co., Ltd.) were dissolved in 83 parts by weight of tetrahydrofuran.
To this, 8 parts by weight of the charge transport material of the following structural formula (2) was added and dissolved, and diluted with cyclohexanone so that the solid content was 8% by weight to prepare a charge transport layer coating solution.

The prepared coating liquid for charge transport layer was spray-coated on the charge generation layer in the same manner as in the case of the undercoat layer to form a charge transport layer.
Then, the surface protection layer (surface layer) which is an ultraviolet curable film (UV curable resin) was formed on the conditions shown below.
Surface layer formulation: 100 parts by weight of tetrahydrofuran, 10 parts by weight of a tri- or higher functional radical polymerizable monomer (trimethylolpropane triacrylate (KAYARAD TMPTA, manufactured by Nippon Kayaku)) having no charge transporting structure, and the following structural formula 10 parts by weight of the radically polymerizable compound having a monofunctional charge transporting structure (3) and 1 part by weight of a photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)) The solvent used for the surface layer was prepared.

In the electrophotographic photoreceptor manufacturing apparatus shown in FIG. 4, the photoreceptor drum formed up to the charge transport layer was set on a work and rotated at 80 rpm with the work.
After spray coating with a film thickness of 5 μm at an oscillating speed of 3.5 mm / s at a distance of 120 mm from the photosensitive drum, the film was dried for 30 minutes, and then irradiated with UV (ultraviolet light) at the following speed to obtain an electrophotographic photosensitive member. Obtained.
(Conditions for electrophotographic photoreceptor manufacturing equipment)
UV irradiation unit: irradiation intensity 240 mW / cm ²
Four types of filters: filters having the transmission characteristics shown in FIG. 5 (manufactured by Koshin Kogyo Co., Ltd., trade name S-UV-340)
-Nitrogen purge of the condensing part of the photosensitive drum-Workpiece rotation (25 rpm)
・ UV irradiation time: 120 seconds ・ Filter cooling unit: Air cooling nozzle is used (air volume 1.5 m ³ / h, cooling air temperature 30 ° C.)

The completed electrophotographic photoreceptor was evaluated as follows.
(1) The elastic power is measured by a load-unloading test with a micro surface hardness tester using a diamond indenter (abbreviation “indenter”).
That is, the indenter is pushed in at a constant load speed from the point (a) where the indenter contacts the sample (loading process), and is stationary for a certain time at the maximum displacement (b) when the set load is reached.
Further, the indenter is pulled up at a constant unloading speed (unloading process), and the point at which no load is finally applied to the indenter is defined as plastic displacement (c).
The indentation depth and load curve of the diamond indenter obtained at this time is recorded as shown in FIG. 6, and the elasticity against the total work (work of plastic deformation + work of elastic deformation) performed by the indenter on the surface layer is recorded from this curve. The elastic work rate is obtained by determining the ratio of the work of deformation.

That is, the elastic power is represented by the following formula.
Elastic work rate (%) = {Work of elastic deformation / (Work of plastic deformation + Work of elastic deformation)} × 100
That is, elastic work rate (%) = work of elastic deformation / (total work)

  The elastic power obtained in Example 1 was set to 1.

(2) Further, the obtained electrophotographic photosensitive member was mounted on all the colors shown in FIG. 1 (with a photosensitive member protective agent coating device for applying the photosensitive member protective agent).
The blank spot evaluation was performed as follows when a 100% clear single color image was output at A4 up to 100k (k = 1000) sheets.
◎: No white spots occur. ○: No more than 3 white spots around the photoconductor. △: No more than 10 white spots around the photoconductor.

(Examples 2 and 3)
Using Example 1 to change the UV irradiation intensity (ultraviolet irradiation intensity) and UV irradiation time (ultraviolet irradiation time) so that the elastic power becomes 1.1 and 1.2 of Example 1, and using clear toner. Only the image device was mounted and the evaluation (2) of Example 1 was performed.
7 and 8 show the relationship between the elastic power, the irradiation intensity, and the irradiation time.
The higher the irradiation intensity or the longer the irradiation time, the higher the elastic power.

(Comparative Example 1)
Only the image forming apparatus using clear toner was mounted with the irradiation power and the irradiation time being changed from Example 1 so that the elastic power becomes 0.8, and the evaluation of Example 1 (2) was performed.
(Comparative Example 2)
Example 2 (2) was evaluated by removing only the photoconductor protective agent coating apparatus from Example 3.

  The results are shown in Table 1.

From Table 1, it can be seen that increasing the elastic power is quite effective against white spots.
It can also be seen that the photoconductor protective agent coating means is also quite effective against white spots.

In the second embodiment, 100% images of two colors of clear + black are output when the image forming device using clear toner is the most upstream and when the black image forming device is upstream of the clear toner image forming device, Table 2 shows the results determined as in Example 1.
The elastic power of the photosensitive member of the clear toner image forming device is 1.2.

When the clear toner image forming device is in the second position, the upstream reverse transfer toner enters the cleaning unit, and therefore white spots due to the reverse transfer toner silica easily occur.
The reverse transfer toner is a toner that moves in the direction opposite to the electric field direction from the intermediate transfer.
The reverse transfer toner is a weakly charged or reversely charged toner and is said to be a toner having a strong non-electrostatic adhesion.

120C, 120M, 120Y, 120K Image forming unit as an image forming device using colored toner 120T Image forming unit as an image forming device using clear toner 122 Photosensitive drum as an image carrier 128 Protection agent coating device

JP 2006-350240 A JP 2009-186610 A Japanese Patent No. 4630893

Claims (6)

An image forming device using colored toner and an image forming device using clear toner, and each image forming device includes an image carrier on which an electrostatic latent image is formed based on image information; In an image forming apparatus that develops an electrostatic latent image formed on each image carrier with a corresponding color toner, and finally transfers the toner image of each color in a state of being superimposed on a recording medium.
The image carrier of the image forming apparatus using the clear toner has a larger elastic power expressed by the following formula on the surface than the image carrier of the image forming apparatus using the colored toner. Image forming apparatus.
Elastic work rate (%) = {Work of elastic deformation / (Work of plastic deformation + Work of elastic deformation)} × 100 The image forming apparatus according to claim 1.
The image carrier of the image forming device using the clear toner is an ultraviolet curable resin having the same prescription as the image carrier of the image forming device using the colored toner, and the elastic work rate is increased by controlling the ultraviolet irradiation time. An image forming apparatus. The image forming apparatus according to claim 1.
The image carrier of the image forming apparatus using the clear toner is an ultraviolet curable resin having the same prescription as the image carrier of the image forming apparatus using the colored toner, and the elastic work rate is increased by controlling the ultraviolet irradiation intensity. An image forming apparatus. The image forming apparatus according to claim 1.
The image carrier of the image forming apparatus using the clear toner is an ultraviolet curable resin having the same formulation as the image carrier of the image forming apparatus using the colored toner, and controls the ultraviolet irradiation time and the ultraviolet irradiation intensity to control elasticity. An image forming apparatus characterized in that the work rate is increased. The image forming apparatus according to any one of claims 1 to 4,
The image forming apparatus using the clear toner is arranged at the most upstream of the toner image transfer order of each image forming apparatus. The image forming apparatus according to any one of claims 1 to 5,
An image forming apparatus comprising: a protective agent coating device that applies a protective agent to a surface of the image carrier.

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