JP2007206193A - Liquid developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid developing device and an image forming apparatus that can improve the utilization efficiency of a liquid developer, while preventing deterioration in the image quality of an obtained image, as well as, are environmentally friendly. <P>SOLUTION: The liquid developing device for forming an image on a recording medium by using a liquid developer having toner particles dispersed in an insulating liquid is equipped with a liquid developer reserving unit for reserving a liquid developer; a developing unit for forming an image by using the liquid developer supplied from the liquid developer reserving unit; a transfer unit for transferring the image formed in the developing unit onto a recording medium to form a transfer image; and a recovering unit for recovering the liquid developer remaining in the developing unit and/or the transfer unit. The insulating liquid contains an unsaturated fatty acid component. The developing device has a degradation determining means for determining the degree of degradation in the liquid developer recovered in the recovering unit, by measuring the changes in colors of the insulating liquid in the recovered liquid developer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid developing device and an image forming apparatus.

Conventionally, as a method for forming an image on a recording medium, a method using a liquid developer in which toner particles are dispersed in an insulating liquid is known.
In general, a liquid developing device applied to such a liquid developer forms an electrostatic latent image by irradiating the surface of the photosensitive drum with light according to image information, and the electrostatic latent image is formed on the electrostatic latent image. On the other hand, the liquid developer supplied from the liquid developer reservoir is attached by a developing roller to form a toner image on the photosensitive drum and transfer the toner image to a recording medium.

In a liquid developing device, generally, in the process of forming a toner image, the liquid developer remaining on the developing roller and the photosensitive drum is collected and reused.
Meanwhile, petroleum-based hydrocarbons, silicone oils, and the like have been conventionally used as insulating liquids that constitute liquid developers. However, in recent years, vegetable oils and animal oils have been used as insulating liquids from the viewpoint of environmental impact and the like. Attempts have been made to use naturally-derived oils and fats such as (see, for example, Patent Document 1).

Since such naturally derived fats and oils are generally easily oxidized, if a liquid developer using such naturally derived fats and oils as an insulating liquid is used in a liquid developing apparatus for a long time, the function as an insulating liquid is achieved. Decreases, and the image quality of the obtained image deteriorates. In particular, the naturally-derived oils and fats in the collected liquid developer have a rapid progress of oxidation, and thus the above-described problem becomes remarkable when the collected liquid developer is reused.
However, it has been difficult to determine the degree of oxidative degradation of such naturally-derived oils and fats in the conventional liquid developing apparatus.

JP 2002-278306 A

  An object of the present invention is to provide an environmentally friendly liquid developing apparatus and an image forming apparatus that can easily determine the degree of deterioration of the liquid developer in the apparatus.

Such an object is achieved by the present invention described below.
The liquid developing device of the present invention is a liquid developing device that forms an image on a recording medium using a liquid developer in which toner particles are dispersed in an insulating liquid.
A liquid developer reservoir for storing the liquid developer;
A developing unit that forms an image using the liquid developer supplied from the liquid developer storing unit;
A transfer unit for transferring an image formed by the developing unit onto the recording medium and forming a transfer image;
A recovery unit that recovers the liquid developer remaining in the developing unit and / or the transfer unit;
The insulating liquid contains an unsaturated fatty acid component,
Deterioration determining means for determining a degree of deterioration of the liquid developer recovered by the recovery unit by measuring a color change of the insulating liquid in the recovered liquid developer. It is characterized by.
Accordingly, it is possible to easily determine the degree of deterioration of the liquid developer in the apparatus, and to provide an environment-friendly liquid developing apparatus and image forming apparatus.

In the liquid developing device of the present invention, the liquid developing device includes a transport unit that transports the liquid developer collected by the collecting unit to the liquid developer storing unit,
It is preferable that the deterioration determination unit is provided in the transport unit.
Since the liquid developer recovered from the developing unit and the transfer unit has a low toner particle content, the color change of the insulating liquid can be measured more easily.

In the liquid developing device according to the aspect of the invention, when the deterioration determination unit determines that the degree of deterioration of the recovered liquid developer is low, the recovered liquid developer is reused to recover the recovered liquid developer. When it is determined that the degree of deterioration of the agent is high, it is preferably discarded.
As a result, it is possible to improve the usage efficiency of the liquid developer while preventing deterioration of the image quality of the obtained image.

In the liquid developing apparatus of the present invention, the liquid developing device includes a separating unit that separates the recovered liquid developer into the toner particles and the insulating liquid.
The measurement of the color change is preferably performed in a state where the toner particles and the insulating liquid are separated by the separation unit.
Thereby, the change in the color of the insulating liquid can be measured more reliably by the deterioration determining means.

In the liquid developing apparatus of the present invention, the separating means stores the recovered liquid developer and separates the toner particles and the insulating liquid by taking out the supernatant in a state where the toner particles are settled. It is preferable that
Thereby, the toner particles and the insulating liquid can be more reliably separated, and the color change of the insulating liquid can be measured more easily.

In the liquid developing apparatus according to the aspect of the invention, it is preferable that the separation unit is a solid-liquid separation filter.
Thereby, the toner particles and the insulating liquid can be more easily and reliably separated, and the color change of the insulating liquid can be measured more easily.
An image forming apparatus of the present invention includes the liquid developing device of the present invention and a fixing device that fixes the image formed on the recording medium.
As a result, it is possible to improve the use efficiency of the liquid developer while preventing the deterioration of the image quality of the obtained image, and to provide an environment-friendly image forming apparatus.

Hereinafter, preferred embodiments of the liquid developing device and the image forming apparatus of the present invention will be described.
<Image forming apparatus>
The image forming apparatus of the present invention forms a toner image on a recording medium using a liquid developer in which toner particles are dispersed in an insulating liquid containing an unsaturated fatty acid component.
FIG. 1 is a schematic view showing a first embodiment of an image forming apparatus (liquid developing device) of the present invention.
As shown in FIG. 1, the image forming apparatus 1000 includes a liquid developing device P100 and a fixing device F40.

[Liquid developing device]
(First embodiment)
First, a first embodiment of a liquid developing apparatus of the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 1, the liquid developing device P100 uses a liquid developer storing portion P1 that stores the liquid developer 1 and an image (toner image) using the liquid developer 1 stored in the liquid developer storing portion P1. ), A transfer unit P3 that transfers the image formed by the development unit P2 to the recording medium 2, a development unit liquid collection unit P4 that collects the liquid developer 1 remaining in the development unit P2, Transfer part liquid recovery part P5 for recovering the liquid developer 1 remaining in the transfer part P3, and recovered liquid developer transport for transporting the liquid developer 1 recovered in the development part liquid recovery part P4 and the transfer part liquid recovery part P5 Part (conveying part) P6, and the recovered liquid developer conveying part (conveying part) P6 for conveying the liquid developer 1 collected by the developing part liquid collecting part P4 and the transfer part liquid collecting part P5 to the liquid developer storing part P1. And a liquid for supplying the liquid developer 1 to the liquid developer reservoir P1 A developer supplying unit P7, and a supplying insulating liquid supply portion P8 of the insulating liquid in the liquid developer reservoir section P1.

The liquid developer storage part P1 has a function of storing the liquid developer 1 in which toner particles are dispersed in an insulating liquid containing an unsaturated fatty acid component.
The developing unit P2 regulates the amount of the supplied liquid developer, the photosensitive member P21 that forms an image, the liquid supply roller P22 partially immersed in the liquid developer 1 in the liquid developer storage unit P1. A liquid thickness regulating roller P23, and a developing roller P24 for supplying a liquid developer to the photosensitive member P21.

  The surface of the photoreceptor P21 is uniformly charged by a charger P211 composed of epichlorohydrin rubber or the like, and then exposed according to information to be recorded by an exposure lamp P212 composed of a laser diode or the like. As a result, an electrostatic latent image is formed. Note that after the transfer of the toner image from the photosensitive member P21 to an intermediate transfer belt P31 described later, the photosensitive member P21 is discharged by the discharging light P213.

The liquid supply roller P22 has a function of supplying the liquid developer to the liquid thickness regulating roller P23.
The liquid thickness regulating roller P23 has a liquid thickness regulating blade P231, and the thickness of the liquid developer on the surface of the liquid thickness regulating roller P23 is kept constant by the liquid thickness regulating blade P231. Then, the liquid developer is transferred from the liquid thickness regulating roller P23 to the developing roller P24.

The developing roller P24 has a function of transferring the liquid developer to the electrostatic latent image on the surface of the photoreceptor P21. The developing roller P24 rotates at the same speed as the photoconductor P21, and transfers the liquid developer to the electrostatic latent image on the surface of the photoconductor P21.
The transfer part P3 has an intermediate transfer belt P31 and a secondary transfer roller P32.
After the toner image formed on the photoconductor P21 is transferred to the intermediate transfer belt P31, a transfer current is passed through the secondary transfer roller P32, and the recording medium 2 such as paper passing between the two is applied. The image is transferred.
Thereafter, the toner image (transfer image) 2a transferred onto the recording medium 2 is fixed using a fixing device F40 as will be described later.

The developing unit liquid recovery unit P4 includes a developing roller upper liquid recovery unit P41 and a photoreceptor upper liquid recovery unit P42.
The developing roller upper liquid recovery unit P41 has a cleaning blade P411, and has a function of recovering the liquid developer 1 remaining on the developing roller P24 after transfer to the photoreceptor P21 by the cleaning blade P411.
Further, the photoconductor upper liquid recovery unit P42 has a cleaning blade P421, and has a function of recovering the liquid developer 1 remaining on the photoconductor P21 after being transferred to the intermediate transfer belt P31 by the cleaning blade P421. .

The transfer part liquid recovery part P5 has a cleaning blade P51 and has a function of recovering the liquid developer 1 remaining on the intermediate transfer belt P31 after transfer to the recording medium 2 by the cleaning blade P51.
As shown in FIG. 1, the recovered liquid developer transport unit P6 has a pump P61. By this pump P61, the developing unit liquid recovery unit P4 (developing roller upper liquid recovery unit P41, photosensitive member upper liquid recovery unit). P42) and the transfer part liquid recovery part P5 have a function of transporting the liquid developer 1 recovered.

Further, the recovery liquid developer transport part P6 is provided with a deterioration determination means P62 for determining the degree of deterioration of the transported liquid developer 1.
The deterioration determination unit P62 determines the degree of deterioration of the liquid developer 1 by measuring a change in the color of the insulating liquid in the conveyed liquid developer 1.
As described above, the present invention includes a deterioration determination unit that determines the degree of deterioration of the recovered liquid developer by measuring a change in the color of the insulating liquid in the recovered liquid developer. It is characterized by a point.

  By having such a deterioration determination means, it is possible to determine the degree of deterioration of the liquid developer (insulating liquid) in the apparatus, which has been difficult to determine in the past. In particular, since an insulating liquid containing an unsaturated fatty acid component has a color change due to deterioration with time, the degree of deterioration of the liquid developer can be easily determined by measuring the color change. Moreover, since the unsaturated fatty acid component applied to the liquid developing device of the present invention is an environmentally friendly component, an environmentally friendly liquid developing device can be provided.

For example, a color difference meter can be used as the deterioration determining means for measuring such a color change.
In the case of using a color difference meter, a transparent portion made of glass, acrylic, quartz, or the like is provided in a part of the recovered liquid developer transport unit P6. And a color difference meter can be installed in this part, and a color change can be measured.

In the present embodiment, the deterioration determining means P62 as described above is provided in the middle of the recovered liquid developer transport unit P6. Since the liquid developer 1 collected from the developing unit P2 and the transfer unit P3 has a low solid content (toner particle) content, the color change of the insulating liquid can be measured more easily.
Further, in the transport direction of the liquid developer 1 in the recovered liquid developer transport section P6, on the upstream side of the deterioration determination means P62 (the side where the developing section liquid recovery section P4 and the transfer section liquid recovery section P5 are provided) Separation means P63 for separating the liquid developer 1 into toner particles and insulating liquid is provided. The solid content in the recovered liquid developer 1 is low in the first place, but by separating the liquid developer 1 into toner particles and insulating liquid in this way, the deterioration determination means P62 is more reliable. The change in color of the insulating liquid can be measured.

  In the present embodiment, as shown in the configuration, the separation unit P63 temporarily stores the conveyed liquid developer 1 and settles the solid content (toner particles), and is provided downstream of the deterioration determination unit P62. The pump P64 is used to take out the supernatant liquid (insulating liquid), thereby separating the solid content from the insulating liquid. Thereby, the toner particles and the insulating liquid can be more reliably separated, and the color change of the insulating liquid can be measured more easily.

In the present embodiment, the recovered liquid developer transport section P6 is provided with a three-way valve P65 on the downstream side in the transport direction of the liquid developer of the pump P64 (deterioration determination means P62).
The three-way valve P65 has a function of switching between feeding the liquid developer 1 (insulating liquid) that has been conveyed into the liquid developer reservoir P1 and discarding the liquid developer 1 outside the liquid developing device P100.

  In the present embodiment, when the deterioration determining unit P62 determines that the degree of deterioration of the conveyed liquid developer 1 (insulating liquid) is low, the transferred liquid developer 1 is used as the liquid developer storage part P1. If the three-way valve P65 is adjusted so that the liquid developer 1 is recovered and reused and it is determined that the degree of deterioration of the conveyed liquid developer 1 is high, the conveyed liquid developer 1 is discarded outside the liquid developing device P100. Adjust the three-way valve P65 to do so. As a result, it is possible to improve the usage efficiency of the liquid developer 1 while preventing deterioration of the image quality of the obtained image.

The liquid developer supply unit P7 has a function of supplying the liquid developer 1 to the liquid developer storage unit P1 described above.
A stirring means P71 is provided in the liquid developer supply part P7. The stirring means P71 is operated by a motor P72 and stirs the liquid developer 1 in the liquid developer supply unit P8.
The insulating liquid supply part P8 has a function of supplying an insulating liquid to the liquid developer storage part P1 described above and adjusting the viscosity and the like of the liquid developer 1 in the liquid developer storage part P1.
Stirring means P81 is provided in the insulating liquid supply part P8. The stirring means P81 is operated by the motor P82 and stirs the insulating liquid in the insulating liquid supply part P8.

The liquid developer supply part P7 and the insulating liquid supply part P8 are connected to the liquid developer storage part P1 by the liquid supply path P9, and the liquid developer or the insulation is supplied by a pump P91 provided in the liquid supply path P9. The liquid is supplied to the liquid developer reservoir P1.
Further, the liquid developer supply part P7 and the insulating liquid supply part P8 are connected to the liquid supply path P9 via the three-way valve P92, and supply of the liquid developer and supply of the insulating liquid as necessary. And can be switched.

(Second Embodiment)
Next, a second embodiment of the liquid developing apparatus of the present invention will be described with reference to the accompanying drawings. Hereinafter, the present embodiment will be described with a focus on differences from the above-described embodiments, and description of similar matters will be omitted.
FIG. 2 is a diagram showing a second embodiment of the image forming apparatus (liquid developing device) of the present invention.

The liquid developing device P100 ′ of the present embodiment has the same configuration as that of the first embodiment described above except that the configuration of the separating unit and the position of the pump in the recovered liquid developer transport unit P6 are different.
In the present embodiment, as shown in FIG. 2, the recovered liquid developer transport unit P6 includes, in order from the downstream side in the transport direction of the liquid developer 1, a separation unit P63 ′, a deterioration determination unit P62, and a three-way valve P65. And a pump P61.
The liquid developer 1 collected by the developing unit liquid collecting unit P4 and the transfer unit liquid collecting unit P5 is conveyed in the collected liquid developer conveying unit P6 by the pump P61.

The liquid developer 1 transported in the recovered liquid developer transport section P6 is removed from the solid content by the separation means P63 ′, and sent to the deterioration determination means P62 having the same configuration as that of the above-described embodiment.
In the present embodiment, a solid-liquid separation filter is used as the separation unit P63 ′. Thereby, the toner particles and the insulating liquid can be more easily and reliably separated, and the color change of the insulating liquid can be measured more easily.
When the deterioration determination unit P62 determines the degree of deterioration and determines that the degree of deterioration is low, the transported liquid developer 1 (insulating liquid) is collected in the liquid developer storage part P1 and reused. If the three-way valve P65 is adjusted to be used and it is determined that the degree of deterioration is high, the three-way valve P65 is adjusted so that the conveyed liquid developer 1 is discarded outside the liquid developing device P100.

[Fixing device]
Next, the fixing device will be described.
FIG. 3 is a cross-sectional view showing an example of a fixing device applied to the image forming apparatus of the present invention.
The fixing device F40 fixes the toner image 2a on the recording medium 2 having the toner image 2a formed by the liquid developing device.

As shown in FIG. 3, the fixing device F40 includes a heat fixing roller F1, a pressure roller F2, a heat-resistant belt F3, a belt stretching member F4, a cleaning member F6, a frame F7, and a spring F9. is doing.
The heat fixing roller (fixing roller) F1 includes a roller base material F1b made of a pipe material, an elastic body F1c covering the outer periphery thereof, and a columnar halogen lamp F1a as a heating source inside the roller base material F1b. It can be rotated counterclockwise as indicated by an arrow in the figure.

The elastic body F1c of the heat fixing roller F1 includes a release layer F11c on its surface layer.
The release layer F11c has a function of preventing toner particles from adhering to the surface of the heat fixing roller F1 during fixing.
Examples of the material constituting the release layer F11c include polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene / hexafluoropropylene copolymer (FEP). And fluorine rubber, silicone rubber and the like.

  Inside the heat fixing roller F1, two columnar halogen lamps F1a and F1a constituting a heating source are incorporated, and the heating elements of these columnar halogen lamps F1a and F1a are arranged at different positions. Yes. Then, by selectively lighting each columnar halogen lamp F1a, F1a, a fixing nip portion where a heat-resistant belt F3, which will be described later, is wound around the heat-fixing roller F1, and a belt stretching member F4, which will be described later, are attached to the heat-fixing roller F1. The temperature controller is easily performed under different conditions from the sliding contact portion, different conditions between the wide recording medium and the narrow recording medium, or the like.

The pressure roller F2 is disposed so as to face the heat fixing roller F1, and is configured to apply pressure to the recording medium 2 on which an unfixed toner image is formed via a heat-resistant belt F3 described later. ing.
The pressure roller F2 includes a roller base material F2b made of a pipe material and an elastic body F2c covering the outer periphery thereof, and is rotatable in the clockwise direction indicated by an arrow in the drawing.

The aforementioned elastic body F1c of the heat fixing roller F1 and the elastic body F2c of the pressure roller F2 are subjected to substantially uniform elastic deformation to form a so-called horizontal nip. Further, since there is no difference in the conveyance speed of the heat-resistant belt F3 (described later) or the recording medium 2 with respect to the peripheral speed of the heat fixing roller F1, extremely stable image fixing is possible.
The heat-resistant belt F3 is an endless annular belt that is stretched around the outer periphery of the pressure roller F2 and the belt stretching member F4 and is movable, and is sandwiched between the heat fixing roller F1 and the pressure roller F2. is there.

  The heat-resistant belt F3 has a thickness of 0.03 mm or more, and its front surface (the surface on which the recording medium 2 is in contact) is formed of PFA, and the rear surface (the pressure roller F2 and the belt stretching member F4 is in contact). The side surface is formed of a seamless tube having a two-layer structure formed of polyimide. The heat-resistant belt F3 is not limited to this, and can be formed of other materials such as a metal tube such as a stainless steel tube or a nickel electroformed tube, or a heat-resistant resin tube such as silicone.

The belt stretching member F4 is disposed upstream of the fixing nip portion between the heat fixing roller F1 and the pressure roller F2 in the recording medium 2 conveyance direction, and an arrow P centering on the rotation shaft F2a of the pressure roller F2. It is arranged so that it can swing in the direction.
The belt stretching member F4 is configured to stretch the heat-resistant belt F3 in the tangential direction of the heat fixing roller F1 in a state where the recording medium 2 does not pass through the fixing nip portion. If the fixing pressure is large at the initial position where the recording medium 2 enters the fixing nip portion, the entry may not be smoothly performed and the recording medium 2 may be fixed with the leading end of the recording medium folded. By adopting a configuration in which F3 is stretched in the tangential direction of the heat fixing roller F1, an inlet port of the recording medium 2 where the recording medium 2 smoothly enters can be formed, and the stable fixing nip portion of the recording medium 2 can be formed. Can enter.

The belt stretching member F4 is fitted into the inner periphery of the heat-resistant belt F3 and cooperates with the pressure roller F2 to apply a tension f to the heat-resistant belt F3 (a heat-resistant belt F3 is a belt). Sliding on the tension member F4). This belt stretching member F4 is disposed at a position where the heat-resistant belt F3 is wound around the heat fixing roller F1 side from the pressing portion tangent L between the heat fixing roller F1 and the pressure roller F2 to form a nip. The protruding wall F4a protrudes from one end or both ends of the belt stretching member F4 in the axial direction. The protruding wall F4a is formed by the heat-resistant belt F3 when the heat-resistant belt F3 approaches one of the axial ends. The contact to the end of the heat-resistant belt F3 is regulated by contacting the wall F4a. A spring F9 is contracted between the end of the protruding wall F4a opposite to the heat fixing roller F1 and the frame, and the protruding wall F4a of the belt stretching member F4 is lightly pressed by the heat fixing roller F1, so that the belt tension is increased. The frame member F4 is positioned in sliding contact with the heat fixing roller F1.
The position where the belt stretching member F4 is lightly pressed against the heat fixing roller F1 is the nip initial position, and the position where the pressure roller F2 is pressed against the heat fixing roller F1 is the nip end position.

  In the fixing device F40, the recording medium 2 on which the unfixed toner image 2a is formed by using an image forming apparatus as described later enters the fixing nip portion from the initial nip position and enters the heat-resistant belt F3 and the heat fixing roller F1. , And the toner image 2a formed on the recording medium 2 is fixed, and then the tangent of the pressing portion of the pressure roller F2 to the heat fixing roller F1. It is discharged in the direction L.

The cleaning member F6 is disposed between the pressure roller F2 and the belt stretching member F4.
The cleaning member F6 is in sliding contact with the inner peripheral surface of the heat-resistant belt F3 to clean foreign matter, abrasion powder, and the like on the inner peripheral surface of the heat-resistant belt F3. By cleaning the foreign matter, wear powder, and the like in this way, the heat-resistant belt F3 is refreshed, and the above-described factor of instability of the friction coefficient is removed. Further, the belt stretching member F4 is provided with a recess F4f, and is configured to store foreign matter, abrasion powder, and the like removed from the heat-resistant belt F3.

  The fixing device F40 has a removing blade (removing means) F12 for removing the insulating liquid adhering (remaining) on the surface of the heat fixing roller F1 after fixing the toner image 2a on the recording medium 2. . The oxidative polymerization accelerator removing blade F12 can remove the insulating liquid and simultaneously remove the toner transferred onto the heat fixing roller F1 at the time of fixing.

  In order to stably drive the heat-resistant belt F3 by the pressure roller F2 and the belt stretching member F4 and stably drive the pressure roller F2, the friction coefficient between the pressure roller F2 and the heat-resistant belt F3 is determined by the belt tension. It is good to set larger than the friction coefficient of the frame member F4 and the heat-resistant belt F3. However, the friction coefficient is such that foreign matter enters between the heat-resistant belt F3 and the pressure roller F2 or between the heat-resistant belt F3 and the belt stretching member F4, or the heat-resistant belt F3, the pressure roller F2, and the belt stretching member. It may become unstable due to wear of the contact portion with F4.

Therefore, the belt tension member F4 and the heat-resistant belt F3 have a winding angle smaller than the winding angle of the pressure roller F2 and the heat-resistant belt F3, and the diameter of the belt stretching member F4 is smaller than the diameter of the pressure roller F2. Set as follows. As a result, the length that the heat-resistant belt F3 slides on the belt stretching member F4 is shortened, which can be avoided from instability factors such as changes with time and disturbances, and the heat-resistant belt F3 is driven stably by the pressure roller F2. Will be able to.
The fixing temperature when fixing the unfixed toner image is preferably 80 to 200 ° C, more preferably 80 to 180 ° C. With such a fixing temperature, the oxidative polymerization reaction of the unsaturated fatty acid component can proceed more effectively, and the fixing strength of the toner particles can be improved more effectively.

<Liquid developer>
Next, the liquid developer applied to the liquid developing device and the image forming apparatus of the present invention will be described in detail.
The liquid developer applied to the liquid developing device and the image forming apparatus of the present invention is one in which toner particles are dispersed in an insulating liquid containing an unsaturated fatty acid component.

[Insulating liquid]
First, the insulating liquid will be described.
The insulating liquid constituting the liquid developer used in the liquid developing device and the image forming apparatus of the present invention contains an unsaturated fatty acid component having an unsaturated bond.
This unsaturated fatty acid component is an environmentally friendly component. Accordingly, it is possible to reduce the load on the environment of the insulating liquid due to leakage of the insulating liquid to the outside of the liquid developing device and disposal of the used liquid developer. As a result, an environmentally friendly liquid developing device can be provided.

  The unsaturated fatty acid component is a component that undergoes oxidative polymerization by heating or the like during fixing. That is, the unsaturated fatty acid component is a component having a function of curing itself by oxidative polymerization and improving the fixing property of the toner particles. Further, since the unsaturated fatty acid component is cured, the fixed toner image can be easily and reliably added with an aqueous ballpoint pen.

Further, since the unsaturated fatty acid component has a high affinity with the toner particles (resin material constituting the toner particles), the toner containing the unsaturated fatty acid component as the insulating liquid as in the present invention can be used as a toner. The dispersibility of the particles can be improved. As a result, it is possible to effectively prevent toner particles from being settled or aggregated during storage.
Examples of unsaturated fatty acids constituting the unsaturated fatty acid component include monounsaturated fatty acids represented by oleic acid, palmitoleic acid, ricinoleic acid, etc., linoleic acid, α-linolenic acid, γ-linolenic acid, arachidonic acid , Polyunsaturated fatty acids typified by docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and the like, and one or more of these can be used.

Among the above-mentioned, it is preferable to use a polyunsaturated fatty acid component, and it is more preferable to use a polyunsaturated fatty acid component having a conjugated unsaturated bond (conjugated unsaturated fatty acid component). Thereby, the oxidative polymerization reaction can proceed more effectively.
As such a conjugated unsaturated fatty acid component, any component having a conjugated unsaturated bond may be used. For example, a synthesized one may be used, or one extracted directly from vegetable oil or the like. May be used, or those obtained by conjugating unsaturated fatty acid components may be used.

Unsaturated fatty acid components as described above are, for example, dehydrated castor oil, tung oil, safflower oil, linseed oil, sunflower oil, corn oil, cottonseed oil, soybean oil, sesame oil, corn oil, cannabis oil, evening primrose oil, blackcurrant oil, borage Oils (borage oil), oils derived from plants such as sardine oil, mackerel oil and herring oil, and oils derived from nature such as oils and fats derived from various animals.
Among the above-mentioned, dehydrated castor oil can be suitably used because it contains a large amount of conjugated linoleic acid component (conjugated unsaturated fatty acid component), and allows the oxidative polymerization reaction to proceed more effectively. As a result, the toner image can be fixed more firmly.

The ratio of the unsaturated fatty acid component to the total fatty acid component in the insulating liquid is not particularly limited, but is preferably 10 mol% or more, more preferably 20 mol% or more, and further preferably 20 to 90 mol%. preferable. Thereby, the oxidation polymerization reaction can be more effectively advanced during fixing.
Further, in the insulating liquid, the unsaturated fatty acid component may take any form. For example, in the insulating liquid, the unsaturated fatty acid component may exist as an unsaturated fatty acid (or a co-unsaturated fatty acid salt), or may be combined with other components to form a compound. Also good. Examples of such compounds include esters of unsaturated fatty acid components and alcohol components (polyhydric alcohol components), amides of unsaturated fatty acid components and amine components (polyhydric amine components), among others, Esters are preferred, and esters of glycerin and unsaturated fatty acid components (hereinafter also referred to as “glycerides”) are more preferred. The formation of the ester as described above in the insulating liquid makes the liquid developer excellent in storage stability and long-term stability, and more excellent in fixing properties of toner particles to the recording medium. Can be.

The insulating liquid may contain, for example, a saturated fatty acid component as shown below in addition to the components described above.
The saturated fatty acid component is a component having a function of keeping the chemical stability of the liquid developer high. Therefore, when a saturated fatty acid component is contained in the insulating liquid, the chemical change of the liquid developer can be effectively prevented, and as a result, the storage stability and long-term stability of the obtained liquid developer are higher. It can be.

Moreover, the saturated fatty acid component has a function of keeping electrical insulation and viscosity high. Therefore, when the insulating liquid contains a saturated fatty acid component, the electrical resistance of the liquid developer can be maintained at a higher level. Further, the transportability of the liquid developer becomes better due to an appropriate viscosity.
Examples of saturated fatty acids constituting such saturated fatty acid components include butyric acid (C4), caproic acid (C6), caprylic acid (C8), capric acid (C10), lauric acid (C12), and myristylic acid (C14). , Palmitic acid (C16), stearic acid (C18), arachidic acid (C20), behenic acid (C22), lignoceric acid (C24) and the like, and one or more selected from these are used in combination. be able to. Among the saturated fatty acids as described above, the number of carbon atoms in the molecule is preferably 6-22, more preferably 8-20, and even more preferably 10-18. . By including a saturated fatty acid component composed of such a saturated fatty acid, the effects as described above are exhibited more significantly.

The saturated fatty acid components as described above are, for example, natural oils and fats such as oils derived from plants such as palm oil (particularly palm kernel oil), coconut oil, and palm oil, and oils and fats derived from various animals (eg butter). Can be obtained efficiently.
When the saturated fatty acid component is contained in the insulating liquid, the ratio of the saturated fatty acid component to the total fatty acid component in the insulating liquid is not particularly limited, but is preferably 0.5 to 40 mol%, More preferably, it is 30 mol%. As a result, the oxidative polymerization reaction can be more effectively advanced at the time of fixing while increasing the electrical insulation of the insulating liquid.

  As described above, when the insulating liquid includes an unsaturated fatty acid component and a saturated fatty acid component, the unsaturated fatty acid component and the saturated fatty acid component may take any form in the insulating liquid. For example, in an insulating liquid, an unsaturated fatty acid component and a saturated fatty acid component are each independently present as an unsaturated fatty acid (or unsaturated fatty acid salt) or a saturated fatty acid (or saturated fatty acid salt). It may be combined with other components to form a compound. Examples of such compounds include unsaturated fatty acid components, esters of saturated fatty acid components and alcohol components (polyhydric alcohol components), unsaturated fatty acid components, amides of saturated fatty acid components and amine components (polyhydric amine components). Among them, an ester is preferable, and an ester of glycerin with an unsaturated fatty acid component and a saturated fatty acid component (hereinafter also referred to as “glyceride”) is more preferable.

  When the insulating liquid contains such ester (glyceride), the content of the ester in the insulating liquid is preferably 90 wt% or more, more preferably 95 wt% or more, and 97 wt%. The above is more preferable. As a result, the oxidative polymerization reaction can proceed more effectively at the time of fixing, with a particularly low environmental load.

Further, the liquid developer (insulating liquid) may contain an antioxidant having a function of preventing and suppressing oxidation of the insulating liquid. Thereby, unintentional oxidation of the unsaturated fatty acid component can be prevented.
Examples of the antioxidants described above include vitamin E such as tocopherol, d-tocopherol, dl-α-tocopherol, acetic acid-α-tocopherol, dl-α-tocopherol acetate, tocopherol acetate, α-tocopherol, etc., dibutylhydroxy Examples include vitamin C such as toluene, butylhydroxyanisole, ascorbic acid, ascorbates, ascorbic acid stearate, green tea extract, fresh coffee extract, sesamol, sesaminol, etc., one or more of these Can be used in combination.

  Among the above, when vitamin E is used, the following effects are obtained. In other words, vitamin E is an environmentally friendly component and a component that has a small influence on a liquid developer caused by oxidation of itself. In particular, vitamin E can be suitably used as an antioxidant because of its high dispersibility in liquids (particularly glycerides) containing unsaturated fatty acid components as described above. Further, the combined use of vitamin E and glycerides as described above can further improve the affinity between the insulating liquid and the toner particles. As a result, the storage stability of the liquid developer, the fixability of the toner particles to the recording medium, and the like are particularly excellent.

  Moreover, among the above-mentioned, when vitamin C is used, the following effects are acquired. That is, like the above-mentioned vitamin E, vitamin C is an environmentally friendly component and a component that has a small influence on a liquid developer due to oxidation of itself. In addition, since vitamin C has a relatively low thermal decomposition temperature, it can sufficiently exhibit its function as an antioxidant during storage of a liquid developer (including idling of an image forming apparatus). At the same time, at the time of fixing, the function as an antioxidant can be reduced, and the oxidative polymerization reaction of the insulating liquid can proceed more reliably.

  The thermal decomposition temperature of the antioxidant is preferably not higher than the fixing temperature at the time of fixing. This effectively prevents deterioration of the insulating liquid during storage of the liquid developer, and at the time of fixing, thermally decomposes the antioxidant in the insulating liquid attached to the surface of the toner particles, The insulating liquid can be effectively cured (oxidative polymerization reaction), and the toner particles can be sufficiently fixed to the recording medium.

Specifically, the thermal decomposition temperature of the antioxidant is preferably 200 ° C. or lower, and more preferably 180 ° C. or lower. Thereby, the fixing strength of the toner particles can be more effectively improved while sufficiently retaining the function as an antioxidant.
The electrical resistance of the insulating liquid as described above at room temperature (20 ° C.) is preferably 1 × 10 ⁹ Ωcm or more, more preferably 1 × 10 ¹¹ Ωcm or more, and 1 × 10 ¹³ Ωcm or more. More preferably.
The dielectric constant of the insulating liquid is preferably 3.5 or less.

<Toner particles>
Next, toner particles will be described.
[Component material of toner particles]
The toner particles (toner) include at least a binder resin (resin material).
1. Resin Material The toner constituting the liquid developer is composed of a material containing a resin material as a main component.

  In the present invention, the resin (binder resin) is not particularly limited, and for example, polystyrene, poly-α-methylstyrene, chloropolystyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer. Polymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-acrylic acid ester -Styrene resin such as methacrylic acid ester copolymer, styrene-α-crawler methyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer, styrene-vinyl methyl ether copolymer, etc. Homopolymer or copolymer containing , Polyester resin, epoxy resin, urethane modified epoxy resin, silicone modified epoxy resin, vinyl chloride resin, rosin modified maleic acid resin, phenyl resin, polyethylene resin, polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene- Examples include an ethyl acrylate copolymer, a xylene resin, a polyvinyl butyral resin, a terpene resin, a phenol resin, an aliphatic or alicyclic hydrocarbon resin, and the like. One or more of these can be used in combination. Among these, when a polyester resin is used, the dispersibility of the toner particles in the liquid developer can be made particularly excellent. This is presumably because the affinity between the polyester resin and the vegetable oil is high.

  Although the softening temperature of resin (resin material) is not specifically limited, It is preferable that it is 50-130 degreeC, It is more preferable that it is 50-120 degreeC, It is further more preferable that it is 60-115 degreeC. In the present specification, the softening temperature is a measurement condition in a Koka type flow tester (manufactured by Shimadzu Corporation): temperature increase rate: 5 ° C./min, softening start temperature defined by a die hole diameter of 1.0 mm. Point to.

2. Colorant The toner may contain a colorant. Examples of the colorant that can be used include pigments and dyes. Examples of such pigments and dyes include carbon black, spirit black, lamp black (CI No. 77266), magnetite, titanium black, chrome lead, cadmium yellow, mineral fast yellow, navel yellow, and naphthol yellow S. , Hansa Yellow G, Permanent Yellow NCG, Chrome Yellow, Benzidine Yellow, Quinoline Yellow, Tartrazine Lake, Red Mouth Lead, Molybdenum Orange, Permanent Orange GTR, Pyrazolone Orange, Benzidine Orange G, Cadmium Red, Permanent Red 4R, Watching Red Calcium salt, eosin lake, brilliant carmine 3B, manganese purple, fast violet B, methyl violet lake, bitumen, cobalt blue, al Reblue Lake, Victoria Blue Lake, First Sky Blue, Indanthrene Blue BC, Ultramarine, Aniline Blue, Phthalocyanine Blue, Calco Oil Blue, Chrome Green, Chrome Oxide, Pigment Green B, Malachite Green Lake, Phthalocyanine Green, Final Yellow Green G, Rhodamine 6G, quinacridone, rose bengal (C.I. No. 45432), C.I. I. Direct Red 1, C.I. I. Direct Red 4, C.I. I. Acid Red 1, C.I. I. Basic Red 1, C.I. I. Modern Tread 30, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 184, C.I. I. Direct Blue 1, C.I. I. Direct Blue 2, C.I. I. Acid Blue 9, C.I. I. Acid Blue 15, C.I. I. Basic Blue 3, C.I. I. Basic Blue 5, C.I. I. Modern Blue 7, C.I. I. Pigment blue 15: 1, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 5: 1, C.I. I. Direct Green 6, C.I. I. Basic Green 4, C.I. I. Basic Green 6, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 180, C.I. I. Pigment Yellow 162, nigrosine dye (CI No. 50415B), metal complex dye, silica, aluminum oxide, magnetite, maghemite, various ferrites, cupric oxide, nickel oxide, zinc oxide, zirconium oxide, titanium oxide, Examples thereof include metal oxides such as magnesium oxide, and magnetic materials containing magnetic metals such as Fe, Co, and Ni, and one or more of these can be used in combination.

3. Other Components The toner may contain components other than those described above. Examples of such components include waxes, charge control agents, magnetic powders, and the like.
Examples of the wax include hydrocarbon waxes such as ozokerite, cercin, paraffin wax, microwax, microcrystalline wax, petrolatum, Fischer-Tropsch wax, carnauba wax, rice wax, methyl laurate, methyl myristate, palmitic acid. Methyl, methyl stearate, butyl stearate, candelilla wax, cotton wax, wood wax, beeswax, lanolin, montan wax, fatty acid ester ester wax, polyethylene wax, polypropylene wax, oxidized polyethylene wax, oxidized polypropylene wax Olefin waxes such as 12-hydroxy stearamide, stearamide, phthalic anhydride amide wax, Lauro , Ketone waxes such as stearone, ether waxes, and the like, can be used singly or in combination of two or more of them.

Examples of the charge control agent include benzoic acid metal salt, salicylic acid metal salt, alkyl salicylic acid metal salt, catechol metal salt, metal-containing bisazo dye, nigrosine dye, tetraphenylborate derivative, quaternary ammonium salt, alkyl Examples include pyridinium salts, chlorinated polyesters, and nitrofunic acid.
Examples of the magnetic powder include magnetite, maghemite, various ferrites, cupric oxide, nickel oxide, zinc oxide, zirconium oxide, titanium oxide, magnesium oxide, and other metal oxides, and magnetic materials such as Fe, Co, and Ni. The thing etc. which were comprised with the magnetic material containing a metal are mentioned.
In addition to the above materials, for example, zinc stearate, zinc oxide, cerium oxide, silica, titanium oxide, iron oxide, fatty acid, fatty acid metal salt, etc. are used as the constituent material (component) of the kneaded product. May be.

[Toner particle shape]
The average particle diameter of the toner particles composed of the above materials is preferably 0.1 to 5 μm, more preferably 0.1 to 4 μm, and further preferably 0.5 to 3 μm. preferable. When the average particle size of the toner particles is a value within the above range, the resolution of an image formed by the liquid developer (toner) can be made sufficiently high.

The average value (average circularity) of the circularity R represented by the following formula (I) for the toner particles constituting the liquid developer is preferably 0.94 to 0.99, and 0.96. More preferably, it is -0.99.
R = L ₀ / L ₁ (I)
(Where, L ₁ [μm] is the circumference of the projected image of the toner particles to be measured, and L ₀ [μm] is the circumference of a perfect circle having an area equal to the area of the projected image of the toner particles to be measured) Represents length)

When the average circularity of the toner particles is within such a range, the insulating liquid can be appropriately contained in the unfixed toner image transferred onto the recording medium, and the fixing strength of the toner particles is higher. Can be.
The content ratio of the toner particles in the liquid developer is preferably 10 to 60 wt%, and more preferably 10 to 30 wt%.

  The liquid developer as described above may be obtained by any method, for example, manufactured by dispersing toner particles obtained by pulverizing a toner material by a pulverization method in an insulating liquid. Or a method for producing a liquid developer using a dispersion obtained by dispersing a toner material in a dispersion medium (for example, as described in the specification of Japanese Patent Application No. 2004-370231). May be manufactured by such a method.

As mentioned above, although this invention was demonstrated based on suitable embodiment, this invention is not limited to these.
For example, each component constituting the liquid developing device and the image forming apparatus of the present invention can be replaced with any one that exhibits the same function, or other configurations can be added.
Further, in the above-described embodiment, the description has been made on the assumption that the toner particles and the insulating liquid are separated from each other.

In the above-described embodiment, the deterioration determination unit is provided in the recovered liquid developer conveyance path. However, the present invention is not limited to this, and each recovery unit may be provided.
In the above-described embodiment, the liquid developing device has been described as having the liquid developer supply unit and the insulating liquid supply unit. However, the liquid developer supply unit and the insulating liquid supply unit may be omitted.

The fixing device applied to the image forming apparatus of the present invention is not limited to the above-described embodiment, and each part constituting the fixing device is replaced with an arbitrary one that exhibits the same function, or other configuration. Can also be added.
In the above-described embodiment, the case where heat is applied during fixing has been described. However, the present invention is not limited to this. For example, ultraviolet rays may be irradiated.
In the above-described embodiment, the heating is described from the fixing roller side. However, the heating may be performed from the pressure roller side.

[1] Production of liquid developer First, as a self-dispersing resin, a polyester resin having a number of —SO ₃ ^— groups (sulfonic acid Na groups) in the side chain (glass transition point: 55 ° C., softening temperature: 123 ° C. )): 80 parts by weight and a cyan pigment as a colorant (manufactured by Dainichi Seika Co., Ltd., Pigment Blue 15: 3): 20 parts by weight were prepared. These components were mixed using a 20 L type Henschel mixer to obtain a raw material for toner production.

Next, this raw material (mixture) was kneaded using a twin-screw kneading extruder. The kneaded product extruded from the extrusion port of the biaxial kneading extruder was cooled.
The kneaded product cooled as described above was coarsely pulverized to obtain a powder having an average particle size of 1.0 mm or less. A hammer mill was used for coarse pulverization of the kneaded product.
Next, 100 parts by weight of the coarsely pulverized product of the kneaded product is added to 250 parts by weight of toluene, and the mixture is treated for 1 hour using an ultrasonic homogenizer (output: 400 μA), whereby the self-dispersing resin of the kneaded product is obtained. A dissolved solution was obtained. In this solution, the pigment was uniformly finely dispersed.

On the other hand, an aqueous liquid composed of 700 parts by weight of ion-exchanged water was prepared.
The stirring speed of this aqueous liquid was adjusted with a homomixer (made by Tokushu Kika Kogyo Co., Ltd.).
The above solution (a kneaded toluene solution) was dropped into the agitated aqueous liquid. As a result, an aqueous emulsion in which the dispersoid having an average particle diameter of 1.2 μm was uniformly dispersed was obtained.
Thereafter, toluene in the aqueous emulsion was removed under the conditions of temperature: 100 ° C. and atmospheric pressure: 80 kPa, and further cooled to room temperature to obtain an aqueous suspension in which solid fine particles were dispersed. In the obtained aqueous suspension, substantially no toluene remained. The solid content (dispersoid) concentration of the obtained aqueous suspension was 30.5 wt%. The average particle size of the dispersoid (solid fine particles) dispersed in the suspension was 0.8 μm. The average particle size of the dispersoid was measured using a laser diffraction / scattering particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.).

The suspension obtained as described above was dried by spray drying, whereby the dispersion medium was removed from the discharged droplets of the aqueous suspension to obtain dry toner particles.
Toner particles obtained: 100 parts by weight, soybean oil as an insulating liquid (manufactured by Nisshin Oilio Co., Ltd.): 500 parts by weight, polyamine aliphatic polycondensation polymer as a dispersant (manufactured by Nippon Lubrizol Co., Ltd., trade name) “Solsperse 11200”): 10 parts by weight and aluminum stearate as a charge control agent: 1 part by weight were prepared.
These components were dispersed using an emulsifying disperser (manufactured by M Technique Co., Ltd.) at a rotational speed of 10000 rpm while being careful not to exceed the glass transition temperature of the resin to obtain a liquid developer A.
The average particle diameter of the toner particles in the obtained liquid developer A was 1.2 μm.

[2] Image formation (Example 1)
The liquid developer obtained as described above is put into the liquid developer reservoir of the liquid developing apparatus shown in FIG. 1, and is not fixed on a recording medium (Fuji Xerox Office Supply, J paper) at room temperature. A toner image having a predetermined pattern was formed, and thereafter, fixing was performed using a fixing device as shown in FIG. This operation was carried out for 8 hours a day for 1 month.
In addition, a color difference meter (manufactured by Siloxane Technology Co., Ltd .: product name “Perceptual Color Sensor PCS-II”) was used as the deterioration determining means. Further, the time point when the change in the color of the collected liquid developer was ΔE> 2 or more in the color difference was judged as deterioration.
(Example 2)
An image was formed and fixed in the same manner as in Example 1 except that the liquid developing apparatus as shown in FIG. 2 was used.

(Comparative Example 1)
An image was formed and fixed in the same manner as in Example 1 except that the recovered liquid developer was directly supplied to the liquid developer reservoir without using the deterioration determination means.
(Comparative Example 2)
An image was formed and fixed in the same manner as in Example 1 except that the recovered liquid developer was not reused.

[3] Evaluation In the examples using the liquid developing apparatus and the image forming apparatus of the present invention, the image quality did not deteriorate even when operated continuously. On the other hand, in Comparative Example 1, the image quality was significantly reduced.
Further, when the amount of the liquid developer in the image forming apparatus one month after the start of the work was measured and the usage efficiency of the liquid developer was examined, in the embodiment, the usage efficiency was higher than that of Comparative Example 2. It was excellent.

1 is a diagram illustrating a first embodiment of an image forming apparatus (liquid developing device) according to the present invention. It is a figure which shows 2nd Embodiment of the image forming apparatus (liquid developing device) of this invention. 1 is a cross-sectional view illustrating an example of a fixing device applied to an image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Liquid developer 1000 ... Image forming apparatus 2 ... Recording medium 2a ... Toner image P100, P100 '... Liquid developing device P1 ... Liquid developer storage part P2 ... Developing part P21 ... Photoconductor P211 ... Charger P212 ... Exposure lamp P213 Destaticizing light P22 ... Liquid supply roller P23 ... Liquid thickness regulating roller P231 ... Liquid thickness regulating blade P24 ... Developing roller P3 ... Transfer section P31 ... Intermediate transfer belt P32 ... Secondary transfer roller P4 ... Developing section liquid collecting section P41 ... Developing roller Upper liquid recovery part P411 ... cleaning blade P42 ... photosensitive member upper liquid recovery part P421 ... cleaning blade P5 ... transfer part liquid recovery part P51 ... cleaning blade P6 ... recovered liquid developer conveying part P61 ... pump P62 ... degradation judging means P63, P63 '... Separation means P64 ... Pump P65 ... Three-way valve P7 ... Liquid development Supply part P71 ... Stirring means P72 ... Motor P8 ... Insulating liquid supply part P81 ... Stirring means P82 ... Motor P9 ... Liquid supply path P91 ... Pump P92 ... Three-way valve F40 ... Fixing device F1 ... Thermal fixing roller (heating roller) F1a ... Column-shaped halogen lamp F1b ... Roller base material F1c ... Elastic body F11c ... Releasing layer F12 ... Removal blade F2 ... Pressure roller F2a ... Rotating shaft F2b ... Roller base material F2c ... Elastic body F3 ... Heat-resistant belt F4 ... Belt tension member F4a ... Projection wall F4f ... Recess F6 ... Cleaning member F7 ... Frame F9 ... Spring

Claims (7)

A liquid developing device that forms an image on a recording medium using a liquid developer in which toner particles are dispersed in an insulating liquid,
A liquid developer reservoir for storing the liquid developer;
A developing unit that forms an image using the liquid developer supplied from the liquid developer storing unit;
A transfer unit for transferring an image formed by the developing unit onto the recording medium and forming a transfer image;
A recovery unit that recovers the liquid developer remaining in the developing unit and / or the transfer unit;
The insulating liquid contains an unsaturated fatty acid component,
Deterioration determining means for determining a degree of deterioration of the liquid developer recovered by the recovery unit by measuring a color change of the insulating liquid in the recovered liquid developer. A liquid developing apparatus characterized by the above. A transport unit that transports the liquid developer recovered by the recovery unit to the liquid developer storage unit;
The liquid developing apparatus according to claim 1, wherein the deterioration determination unit is provided in the transport unit.   When the deterioration determining unit determines that the degree of deterioration of the collected liquid developer is low, the recovered liquid developer is reused, and the degree of deterioration of the recovered liquid developer is high. The liquid developing device according to claim 1, wherein the liquid developing device is discarded when judged. Separating means for separating the recovered liquid developer into the toner particles and the insulating liquid;
4. The liquid developing device according to claim 1, wherein the color change is measured in a state where the toner particles and the insulating liquid are separated by the separating unit.   5. The separation unit according to claim 4, wherein the separation unit stores the collected liquid developer and separates the toner particles and the insulating liquid by taking out a supernatant in a state where the toner particles are settled. Liquid developing device.   The liquid developing apparatus according to claim 4, wherein the separation unit is a solid-liquid separation filter. An image forming apparatus comprising: the liquid developing device according to claim 1; and a fixing device that fixes the image formed on the recording medium.

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