JP4674530B2 - Fixing method, fixing device, and image forming apparatus - Google Patents

Description

The present invention relates to a fixing method , a fixing 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 this method using a liquid developer, toner particles are more effectively prevented from agglomerating than dry toner using toner in a dry state, so that fine toner particles can be used. As described above, those having a low softening point (low softening temperature) can be used. As a result, an image forming apparatus using a liquid developer has characteristics that fine line image reproducibility, gradation reproducibility, and color reproducibility can be obtained. .

As the insulating liquid used for the liquid developer, petroleum-based hydrocarbons, silicone oils, and the like are generally used because of their high chemical stability.
However, the method using a liquid developer has a problem that the insulating liquid adhering to the surface of the toner particles at the time of fixing permeates into the recording medium and reduces the fixing strength. In addition, there is also a problem that it becomes difficult to add information to the recording medium with a ballpoint pen or the like due to this soaking.

In order to solve such a problem, an attempt has been made to remove the insulating liquid using a blade or the like before transferring the toner particles to the recording medium (see, for example, Patent Document 1).
However, with such a method, it is difficult to sufficiently remove the insulating liquid, and it is difficult to obtain a sufficient fixing strength. In order to improve the fixing strength of the toner, it may be possible to fix the toner particles by heating at a relatively high temperature for a long time, but it satisfies the recent demand for higher speed and energy saving of image formation. It was difficult.

JP 2004-286859 A

An object of the present invention is to provide a fixing method , a fixing device, and an image forming apparatus capable of firmly fixing toner particles on a recording medium.

Such an object is achieved by the present invention described below.
Fixing method of the present invention, a fixing method for fixing the formed image on the recording medium body using a liquid developer comprising an insulating liquid and toner particles comprising an unsaturated fatty acid component, in the recording medium member by the fixing roller Because
An application step of applying an oxidative polymerization accelerator for accelerating the oxidative polymerization reaction of the unsaturated fatty acid component to the fixing roller surface ;
In the fixing step, and the unsaturated fatty acid component contained in the image, the fixing roller is brought into contact with the granted the oxidation polymerization accelerator, and a fixing step of fixing the image on the recording medium body,
Characterized in that it have a.

  Thus, the toner particles can be firmly fixed on the recording medium without heating to a particularly high temperature. Further, since a large amount of heat is not required for fixing, the toner particles can be sufficiently fixed on the recording medium even if the time for passing through the fixing nip is relatively short. That is, since fixing does not take time, the printing speed can be further increased. Further, since a large amount of heat is not required for fixing, energy saving can be achieved.

In the fixing method of the present invention, the oxidative polymerization accelerator is preferably a fatty acid metal salt.
Thereby, the oxidative polymerization reaction of the unsaturated fatty acid component can be caused more reliably.
The fixing method of the present invention, the oxidation polymerization accelerator, it is preferably dispersed or dissolved in an inert liquid to the oxidation polymerization accelerator.
Thereby, unintentional alteration of the oxidative polymerization accelerator can be effectively prevented, and the function of the oxidative polymerization accelerator can be exhibited without impairing the function.

The fixing method of the present invention, the inert liquid in the oxidation polymerization accelerator is preferably a fat having saturated fatty acid component.
Oils and fats composed of saturated fatty acid components are liquids that are particularly excellent in dispersibility of fatty acid metal salts. Oils and fats composed of saturated fatty acid components are environmentally friendly components. Therefore, it is possible to reduce an environmental load due to leakage outside the fixing device or disposal.
In the fixing method of the present invention, the temperature of the fixing roller is preferably 80 to 200 ° C.
Thereby, 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.

The fixing device of the present invention includes a fixing roller,
Wherein the fixing row La, and having a oxidation polymerization accelerator imparting unit that imparts oxidation polymerization accelerator, a.
Thus, the toner particles can be firmly fixed on the recording medium without heating to a particularly high temperature. Further, since a large amount of heat is not required for fixing, the toner particles can be sufficiently fixed on the recording medium even if the time for passing through the fixing nip is relatively short. That is, since fixing does not take time, the printing speed can be further increased. Further, since a large amount of heat is not required for fixing, energy saving can be achieved.

The fixing device of the present invention preferably has a pressure roller that presses against the fixing roller and applies pressure to the recording medium.
As a result, an oxidative polymerization reaction of the unsaturated fatty acid component can be caused more reliably and fixed more firmly.

In the fixing device of the present invention, the oxidation polymerization accelerator deposition unit is preferably low la.
Thereby, the oxidation polymerization accelerator can be applied more uniformly on the fixing roller.
In the fixing device of the present invention, the oxidation polymerization accelerator deposition unit is preferably a brush.
Thereby, the oxidation polymerization accelerator can be applied more uniformly on the fixing roller.

In the fixing device of the present invention, after fixing the image on the recording medium preferably has an oxidation polymerization accelerator removal unit for removing the oxidation polymerization accelerator attached to the fixing low la.
Thereby, the surface state of the fixing roller when applying the oxidative polymerization accelerator can be improved, and the oxidative polymerization accelerator can be applied more uniformly.
An image forming apparatus of the present invention includes a liquid developer storage unit that stores a liquid developer having an insulating liquid containing an unsaturated fatty acid component and toner particles,
A developing unit for developing using the liquid developer supplied from the liquid developer storage unit;
An image carrier;
A transfer unit for transferring an image developed on the image carrier by the developing unit to a recording medium;
Fixing roller for fixing the image on the recording medium, a pressure roller for pressing the fixing roller to apply pressure to the recording medium, and an oxidation polymerization accelerator for promoting an oxidation polymerization reaction of the unsaturated fatty acid component A fixing portion having an oxidation polymerization accelerator providing means for providing
It is characterized by providing.

Hereinafter, preferred embodiments of the fixing method , the fixing device, and the image forming apparatus of the present invention will be described.
In the fixing method of the present invention, when an insulating liquid that contains an unsaturated fatty acid component is used as an insulating liquid constituting the liquid developer, a toner image on a recording medium formed with the liquid developer is fixed by a fixing roller. In addition, the unsaturated fatty acid component contained in the toner image is brought into contact with an oxidative polymerization accelerator that accelerates the oxidative polymerization of the unsaturated fatty acid component, whereby the unsaturated fatty acid component is oxidatively polymerized. ing.

<< First Embodiment >>
<Fixing device>
First, a first embodiment of a fixing device applied to a fixing method of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing a first embodiment of a fixing device to which the fixing method of the present invention is applied.

The fixing device F40 fixes the toner image F5a on the recording medium F5 having the toner image F5a formed by the image forming apparatus described in detail later.
As shown in FIG. 1, 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 an oxidation polymerization accelerator. It has a roller F8 and a spring F9.

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 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 pressure roller F2 is arranged so as to be in contact with the heat fixing roller F1, and is configured to apply pressure to the recording medium F5 on which an unfixed toner image is formed at a portion in contact with the heat fixing roller F1. Yes.
A PFA layer is provided on the surface layer of the elastic body F1c of the heat fixing roller F1. As a result, the elastic bodies F1c and 2c have different thicknesses, but the elastic bodies F1c and 2c are substantially uniformly elastically deformed to form a so-called horizontal nip, and with respect to the peripheral speed of the heat fixing roller F1. Since there is no difference in the conveyance speed of the heat-resistant belt F3 or the recording medium F5, which will be described later, extremely stable image fixing is possible.

  In addition, two columnar halogen lamps F1a and F1a constituting a heating source are built in the heat fixing roller F1, 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 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 F5 comes into 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 may 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 silicon.

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 conveyance direction of the recording medium F5, and has an arrow P around the rotation axis 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 F5 does not pass through the fixing nip portion. If the fixing pressure is large at the initial position where the recording medium F5 enters the fixing nip portion, the entry may not be smoothly performed and the recording medium F5 may be fixed in a state where the tip of the recording medium F5 is broken. 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 F5 through which the recording medium F5 enters smoothly can be formed, and the stable fixing nip portion of the recording medium F5 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, a recording medium F5 on which an unfixed toner image F5a is formed using an image forming apparatus as will be 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 unfixed toner image F5a formed on the recording medium F5 is fixed, and then the tangential direction of the pressing portion of the pressure roller F2 to the heat fixing roller F1 Discharged to 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 oxidation polymerization accelerator imparting roller F8 is disposed so as to be in contact with the heat fixing roller F1, and performs an oxidation polymerization reaction of an unsaturated fatty acid component in a liquid developer (insulating liquid) described in detail later on the heat fixing roller F1. It has a function of imparting an oxidative polymerization accelerator to promote.
By the way, in the conventional fixing method (fixing apparatus) using a liquid developer, there is a problem that the insulating liquid adhering to the surface of the toner particles permeates into the recording medium at the time of fixing, thereby reducing the fixing strength. . In addition, there is also a problem that it becomes difficult to add information to the recording medium with a ballpoint pen or the like due to this soaking.

  In order to solve such a problem, an attempt is made to remove the insulating liquid using a blade or the like before transferring the toner particles to the recording medium. It was difficult to remove the liquid, and it was difficult to obtain sufficient fixing strength. In order to improve the fixing strength of the toner, it may be possible to fix the toner particles by heating at a relatively high temperature for a long time, but it satisfies the recent demand for higher speed and energy saving of image formation. It was difficult.

  On the other hand, in the present invention, the unsaturated fatty acid component is brought into contact with the oxidative polymerization accelerator provided on the fixing roller by the oxidative polymerization accelerator providing means as described above, and the unsaturated fatty acid component is oxidatively polymerized. It has characteristics. That is, the present invention uses an insulating liquid that contains an unsaturated fatty acid component as an insulating liquid constituting the liquid developer, and provides an oxidative polymerization accelerator that accelerates the oxidative polymerization reaction of the unsaturated fatty acid component on the fixing roller. (Applying Step) When an unfixed toner image on a recording medium formed with a liquid developer is fixed with a fixing roller (fixing step), an unsaturated fatty acid component contained in the toner image and the fixing roller It is characterized in that the unsaturated fatty acid component is oxidatively polymerized by bringing it into contact with the oxidative polymerization accelerator imparted thereto.

Thus, when the toner image is fixed on the recording medium, an oxidation polymerization reaction of the unsaturated fatty acid component in the insulating liquid is generated, so that the toner particles can be placed on the recording medium without heating to a particularly high temperature. Can be firmly fixed. Further, since a large amount of heat is not required for fixing, the toner particles can be sufficiently fixed on the recording medium even if the time for passing through the fixing nip is relatively short. That is, since fixing does not take time, the printing speed can be further increased. Further, since a large amount of heat is not required for fixing, energy saving can be achieved.
The liquid developer and the oxidation polymerization accelerator will be described in detail later.

  In the present embodiment, as a means for applying the oxidation polymerization accelerator, a roller-shaped one is used. Thereby, the oxidation polymerization accelerator can be applied more uniformly on the heat fixing roller F1. As a result, at the time of fixing, the oxidative polymerization accelerator and the unsaturated fatty acid component can be more reliably brought into contact with each other. Such an effect becomes more prominent when the oxidative polymerization accelerator is applied using a solution or dispersion in a liquid.

Further, the fixing device F40 includes an oxidation polymerization accelerator supply unit F81 that supplies an oxidation polymerization accelerator to the oxidation polymerization accelerator applying roller F8.
Further, the fixing device F40 fixes the toner image F5a on the recording medium F5 and then removes the oxidation polymerization accelerator that adheres (residual) to the surface of the heat fixing roller F1 (oxidation polymerization accelerator removal blade). Removing means) F11. Thereby, the surface state of the heat fixing roller F1 when applying the oxidation polymerization accelerator can be improved, and the oxidation polymerization accelerator can be applied more uniformly. The oxidative polymerization accelerator removing blade F11 can remove the oxidative polymerization accelerator and simultaneously remove the insulating liquid transferred onto the heat fixing roller F1 during 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 time required for the toner particles to pass through the fixing nip portion (nip time) is preferably 0.02 to 0.2 seconds, and more preferably 0.03 to 0.1 seconds. Even if the time required for the toner particles to pass through the fixing nip is such a short time, the toner particles can be sufficiently fixed, and the printing speed can be increased.
The fixing device F40 is suitable for high-speed printing (high-speed fixing, high-speed image formation). Specifically, the feeding speed (feeding speed) of the recording medium F5 is 0.05 to 0.5 m / second. It is preferable that it is 0.15 to 0.4 m / sec. As described above, according to the present invention, it is possible to effectively prevent occurrence of poor fixing of toner particles even when toner is fixed on a recording medium at a relatively high speed.
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 used in the present invention will be described in detail.
The liquid developer used in 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 present invention contains an unsaturated fatty acid component having an unsaturated bond.
This unsaturated fatty acid component is a component that undergoes oxidative polymerization by contacting with an oxidative polymerization accelerator that will be described in detail later 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.

The unsaturated fatty acid component is an environmentally friendly component. Therefore, 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 fixing device and disposal of the used liquid developer. As a result, an environmentally friendly fixing device can be provided.
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.

In addition, 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 included in the insulating liquid, 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 antioxidant 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 content of the antioxidant in the insulating liquid is preferably 0.01 to 15 parts by weight and more preferably 0.1 to 7 parts by weight with respect to 100 parts by weight of the insulating liquid. 1 to 7 parts by weight is more preferable. As a result, it is possible to more efficiently prevent curing of the insulating liquid (oxidation polymerization reaction) when necessary (during fixing) while more reliably preventing deterioration of the insulating liquid due to oxidation during storage of the liquid developer. Can do.
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.
(Constituent 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 due to the similarity in chemical structure between the polyester resin and the insulating liquid described in detail later (particularly when the insulating liquid is composed of an ester of glycerin and an unsaturated fatty acid component). it is conceivable that.

  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 wax such as 12-hydroxystearic acid amide, stearic acid amide, amide anhydride such as phthalic anhydride, 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 20 to 50 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.

<Oxidation polymerization accelerator>
The oxidative polymerization accelerator used in the present invention is not particularly limited as long as it promotes oxidative polymerization of an unsaturated fatty acid component, but it is preferable to use a fatty acid metal salt. Thereby, the oxidative polymerization reaction of the unsaturated fatty acid component can be caused more reliably.
Examples of such fatty acid metal salts include resin acid metal salts (for example, cobalt salts, manganese salts, lead salts, etc.), linolenic acid metal salts (for example, cobalt salts, manganese salts, lead salts, etc.), and metal octylates. Salt (for example, cobalt salt, manganese salt, lead salt, zinc salt, calcium salt, etc.), naphthenic acid metal salt (for example, zinc salt, calcium salt, etc.), etc. They can be used in combination.

Such an oxidation polymerization accelerator may be applied as it is in the form of a powder, or may be applied in a state dispersed or dissolved in a liquid, that is, as an oxidation polymerization accelerator-containing liquid. .
When applied as an oxidation polymerization accelerator-containing liquid, the oxidation polymerization accelerator can be applied more uniformly on the heat fixing roller F1.

As the liquid for dispersing or dissolving the oxidative polymerization accelerator, it is preferable to use a liquid inert to the oxidative polymerization accelerator. Thereby, unintentional alteration of the oxidative polymerization accelerator can be effectively prevented, and the function of the oxidative polymerization accelerator can be exhibited without impairing the function.
Examples of the liquid inert to the oxidative polymerization accelerator include mineral oil and fats and oils mainly composed of the saturated fatty acid component as described above.

Among these, fats and oils composed of saturated fatty acid components are liquids that are particularly excellent in dispersibility of fatty acid metal salts. Oils and fats composed of saturated fatty acid components are environmentally friendly components. Therefore, it is possible to reduce an environmental load due to leakage outside the fixing device or disposal. As a result, an environmentally friendly fixing device can be provided.
The content of the oxidation polymerization accelerator in the oxidation polymerization accelerator-containing liquid is preferably 0.5 to 5.0 wt%, more preferably 0.5 to 3.0 wt%. Thereby, the oxidation polymerization reaction of an unsaturated fatty acid component can be advanced more efficiently.

<Image forming apparatus>
The (unfixed) toner image on the recording medium can be formed using, for example, an image forming apparatus described below.
FIG. 2 is a diagram illustrating an example of a contact-type image forming apparatus.
The image forming apparatus P1 includes a developer container P11 for storing a liquid developer, a cylindrical photosensitive member (developing unit) P2 for developing an image (toner image), and a liquid developer from the developer container P11 to the photosensitive member P2. And an intermediate transfer (transfer portion) roller P18 for transferring an image developed by the photosensitive member P2 to a recording medium.

The surface of the photoreceptor P2 is uniformly charged by a charger P3 made of epichlorohydrin rubber or the like, and then subjected to exposure P4 in accordance with information to be recorded by a laser diode or the like, whereby an electrostatic latent image is obtained. An image is formed.
The developing device P10 has a coating roller P12 partly immersed in a developer container P11 and a developing roller P13. The application roller P12 is, for example, a metal gravure roller such as stainless steel, and rotates to face the developing roller P13. Further, a liquid developer coating layer P14 is formed on the surface of the coating roller P12, and the thickness thereof is kept constant by the metering blade P15.

Then, the liquid developer is transferred from the coating roller P12 to the developing roller P13. The developing roller P13 has a low hardness silicone rubber layer on a roller core P16 made of metal such as stainless steel, and a conductive PFA (polytetrafluoroethylene-perfluorovinyl ether copolymer) resin on the surface thereof. A layer is formed, and rotates at the same speed as the photosensitive member P2 to transfer the liquid developer to the latent image portion. The liquid developer remaining on the developing roller P13 after being transferred to the photoreceptor P2 is removed by the developing roller cleaning blade P17 and collected in the developer container P11.
Further, after the transfer of the toner image from the photoreceptor P2 to the intermediate transfer roller P18, the photoreceptor P2 is neutralized by the neutralizing light P21, and the transfer residual toner remaining on the photoreceptor P2 is urethane rubber or the like. It is removed by the configured cleaning blade P22.

Similarly, residual toner remaining on the intermediate transfer roller P18 after being transferred from the intermediate transfer roller P18 (transfer portion) to the recording medium F5 is removed by a cleaning blade P23 made of urethane rubber or the like.
After the toner image formed on the photoreceptor P2 is transferred to the intermediate transfer roller P18, a transfer current is applied to the secondary transfer roller P19, and the recording medium F5 such as paper passing between the two is applied to the recording medium F5. The image is transferred.
Thereafter, the toner image (transfer image) transferred onto the recording medium F5 such as paper is conveyed to the fixing device F40 described above and fixed.

  FIG. 3 shows an example of a non-contact type image forming apparatus. In the non-contact method, the developing roller P13 is provided with a charging blade P24 made of a phosphor bronze plate. The charging blade P24 has a function of making frictional charging in contact with the liquid developer layer. Since the application roller P12 is a gravure roller, a developer layer corresponding to the unevenness of the surface of the gravure roller is formed on the development roller P13. Therefore, it functions to uniformly level the unevenness, and the arrangement direction may be either the counter direction or the trail direction with respect to the rotation direction of the developing roller, and may be a roller shape instead of a brate shape.

Further, an interval of 200 μm to 800 μm is provided between the developing roller P13 and the photosensitive member P2, and a frequency of 500 to 3000 Vpp superimposed on a direct current voltage of 200 to 800 V is applied between the developing roller P13 and the photosensitive member P2. An AC voltage of 50 to 3000 Hz is preferably applied. Other than that, it is the same as the image forming apparatus described with reference to FIG.
In FIGS. 2 and 3, image formation using a single color liquid developer has been described. However, when forming an image using a plurality of color toners, an image of each color is formed using a plurality of color developers. Thus, a color image can be formed.

<< Second Embodiment >>
Next, a second embodiment of a fixing device applied to the fixing method 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. 4 is a sectional view showing a second embodiment of a fixing device applied to the fixing method of the present invention.
As shown in FIG. 4, the fixing device F40 ′ has an oxidation polymerization accelerator application brush F8 ′ as an oxidation polymerization accelerator application unit, and the first embodiment described above in that the shape is a brush shape. Is different.

As described above, when the oxidation polymerization accelerator providing means is in a brush shape, the oxidation polymerization accelerator can be applied more uniformly to the heat fixing roller F1. In particular, when the oxidative polymerization accelerator is applied in the form of a powder, the above-described effect appears more remarkably.
As mentioned above, although this invention was demonstrated based on suitable embodiment, this invention is not limited to these.

For example, in the fixing method of the present invention, one or two or more optional steps may be added.
In addition, each unit constituting the fixing device applied to the fixing method of the present invention can be replaced with an arbitrary one that exhibits the same function, or another configuration can be added.
In the above-described embodiment, thermal fixing has been described. However, thermal fixing may not be performed. For example, fixing may be performed by ultraviolet irradiation.

  Further, the fixing device of the present invention is not limited to the device described above. For example, as shown in FIG. 5, the oxidation polymerization accelerator applying roller (oxidation polymerization accelerator applying means) F8 may be arranged so as to be in contact with the heat-resistant belt F3 (pressure roller F2). In other words, the oxidation polymerization accelerator is applied to the pressure roller F2 side in the fixing unit including the heat fixing roller F1 and the pressure roller F2. In such a configuration, an oxidation polymerization accelerator is applied from the surface (hereinafter also referred to as the back surface) opposite to the surface (hereinafter also referred to as the front surface) on which the unfixed toner image F5a of the recording medium F5 is formed. To be. For example, when a solution obtained by dispersing or dissolving an oxidative polymerization accelerator in a liquid is applied on the heat-resistant belt F3, the oxidative polymerization accelerator is infiltrated from the back surface, and the liquid in the insulating liquid that has infiltrated from the front surface side. Contacting with the saturated fatty acid component, the oxidative polymerization reaction of the unsaturated fatty acid component can proceed. Therefore, with such a configuration, the toner image is firmly fixed on the recording medium, and the unsaturated fatty acid and the oxidation polymerization accelerator do not come into contact with each other on the surface of the fixing roller. It is possible to effectively prevent the deposited material from adhering. The same applies to the pressure roller side.

[1] Manufacture of liquid developer (Manufacture of liquid developer A)
First, as a self-dispersing resin, a polyester resin having a large number of —SO ₃ ^— groups (sulfonic acid Na group) in the side chain (glass transition point: 55 ° C., softening temperature: 123 ° C.): 80 parts by weight; A cyan pigment (manufactured by Dainichi Seika Co., Ltd., Pigment Blue 15: 3): 20 parts by weight as a colorant was 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: 40 parts by weight, dehydrated castor oil as an insulating liquid (manufactured by Ito Oil Co., Ltd.): 160 parts by weight, polyamine aliphatic polycondensation polymer as a dispersant (manufactured by Nippon Lubrizol Co., Ltd., trade name “ Solsperse 11200 "): 4 parts by weight and magnesium stearate as a charge control agent: 0.56 parts 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.
In the obtained liquid developer A, the average particle diameter of the toner particles was 1.0 μm, and the standard deviation of the particle diameter between the toner particles was 0.45 μm.

(Manufacture of liquid developer B)
First, an epoxy resin as a resin material (Epicoat 1004, softening temperature T _f : 128 ° C.): 80 parts by weight and a cyan pigment as a coloring agent (Pigment Blue 15: 3, manufactured by Dainichi Seika Co., Ltd.): 20 parts by weight And 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 using a cooling machine. The cooled kneaded product was pulverized to obtain a powder (ground product) 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 obtained as described above, 100 parts by weight of methyl oleate as the first liquid, and a polyamine aliphatic polycondensate as a dispersant (manufactured by Nippon Lubrizol Co., Ltd.) , Trade name “Solsperse 11200”): 10 parts by weight and magnesium stearate as a charge control agent: 1.4 parts by weight were prepared.

These components were put into a ball mill and wet pulverized for 200 hours to obtain a pulverized dispersion. Thereafter, 100 parts by weight of the obtained pulverized dispersion was mixed with 400 parts by weight of safflower oil (Nisshin Oilio Co., Ltd.) as the second liquid to obtain a liquid developer B.
In the obtained liquid developer B, the average particle diameter of the toner particles was 1.5 μm, and the standard deviation of the particle diameter between the toner particles was 0.48 μm.

(Manufacture of liquid developer C)
First, an epoxy resin as a resin material (Epicoat 1004, softening temperature T _f : 128 ° C.): 80 parts by weight and a cyan pigment as a coloring agent (Pigment Blue 15: 3, manufactured by Dainichi Seika Co., Ltd.): 20 parts by weight And 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 using a cooling machine. The cooled kneaded product was pulverized to obtain a powder (ground product) having an average particle size of 1.0 mm or less. A hammer mill was used for coarse pulverization of the kneaded product.
Next, the coarsely pulverized product obtained as described above: 100 parts by weight, Isopar H (trade name of Exxon Chemical Co., Ltd.): 100 parts by weight, and polyamine aliphatic polycondensate (Nippon Lubrizol as a dispersant) 10 parts by weight, and 1.4 parts by weight of magnesium stearate as a charge control agent were prepared.

These components were put into a ball mill and wet pulverized for 200 hours to obtain a pulverized dispersion. Thereafter, 100 parts by weight of the obtained pulverized material dispersion and 400 parts by weight of Isopar H were mixed to obtain a liquid developer C.
In the obtained liquid developer C, the average particle diameter of the toner particles was 1.5 μm, and the standard deviation of the particle diameter between the toner particles was 0.48 μm.

[2] Fixing to recording medium (Example 1)
The liquid developer A obtained as described above was put into the image forming apparatus shown in FIG. 2, and an unfixed toner image was formed on a recording medium (J paper manufactured by Fuji Xerox Office Supply).
The formed unfixed toner image was fixed on a recording medium using a fixing device as shown in FIG.

The fixing device includes a heat fixing roller having a 30 μm PFA coating on the surface of an aluminum core (outer diameter φ30 mm, length 240 mm, wall thickness 1 mm), and an outer diameter formed of heat vulcanizing silicone rubber. A roller having a pressure roller having a diameter of 30 mm, a length of 240 mm, and a thickness of 7 mm was used. Further, as a heating source in the heat fixing roller, a halogen lamp having a light emitting part length of 240 mm, a total length of 292 mm, and 850 watts was used. The pressure contact force of the pressure roller was 4 kg, and the nip width was about 8 mm. The fixing temperature was set to 160 ° C. The conveyance speed of the recording medium of the fixing device was 200 mm / second.
In addition, an oxidation polymerization accelerator-containing liquid in which cobalt octylate as an oxidation polymerization accelerator was dissolved in saturated fatty acid triglyceride (manufactured by NOF Corporation, trade name “Panasate 800”) was added to the oxidation polymerization accelerator supply unit. The content of cobalt octylate in the oxidative polymerization accelerator-containing liquid was 1 wt%.

(Example 2)
As the oxidation polymerization accelerator-containing liquid, the same as Example 1 except that an oxidation polymerization accelerator-containing liquid (trade name “Octolife Co 8%” manufactured by Shinto Fine Co., Ltd.) in which cobalt octylate was dissolved in mineral oil was used. Fixing was performed.
(Example 3)
Fixing was performed in the same manner as in Example 1 except that the liquid developer B obtained as described above was used as the liquid developer.

Example 4
Fixing was carried out in the same manner as in Example 1 except that cobalt linolenate was used as the oxidative polymerization accelerator.
(Example 5)
The liquid developer A obtained as described above was put into the image forming apparatus shown in FIG. 2, and an unfixed toner image was formed on a recording medium (J paper manufactured by Fuji Xerox Office Supply).
The formed unfixed toner image was fixed on a recording medium using a fixing device as shown in FIG.

The fixing device includes a heat fixing roller having a 30 μm PFA coating on the surface of an aluminum core (outer diameter φ30 mm, length 240 mm, wall thickness 1 mm), and an outer diameter formed of heat vulcanizing silicone rubber. A roller having a pressure roller having a diameter of 30 mm, a length of 240 mm, and a thickness of 7 mm was used. Further, as a heating source in the heat fixing roller, a halogen lamp having a light emitting part length of 240 mm, a total length of 292 mm, and 850 watts was used. The pressure contact force of the pressure roller was 4 kg, and the nip width was about 8 mm. The fixing temperature was set to 160 ° C. The conveyance speed of the recording medium of the fixing device was 200 mm / second.
Further, cobalt octylate powder as an oxidative polymerization accelerator was charged into the oxidative polymerization accelerator supply section.

(Example 6)
Fixing was performed in the same manner as in Example 6 except that the liquid developer B obtained as described above was used as the liquid developer.
(Example 7)
Fixing was carried out in the same manner as in Example 1 except that zinc naphthenate was used as the oxidative polymerization accelerator.

(Example 8)
The liquid developer A obtained as described above was put into the image forming apparatus shown in FIG. 2, and an unfixed toner image was formed on a recording medium (J paper manufactured by Fuji Xerox Office Supply).
The formed unfixed toner image was fixed on a recording medium using a fixing device as shown in FIG.

The fixing device includes a heat fixing roller having a 30 μm PFA coating on the surface of an aluminum core (outer diameter φ30 mm, length 240 mm, wall thickness 1 mm), and an outer diameter formed of heat vulcanizing silicone rubber. A roller having a pressure roller having a diameter of 30 mm, a length of 240 mm, and a thickness of 7 mm was used. Further, as a heating source in the heat fixing roller, a halogen lamp having a light emitting part length of 240 mm, a total length of 292 mm, and 850 watts was used. The pressure contact force of the pressure roller was 4 kg, and the nip width was about 8 mm. The fixing temperature was set to 160 ° C. The conveyance speed of the recording medium of the fixing device was 200 mm / second.
In addition, an oxidation polymerization accelerator-containing liquid in which cobalt octylate as an oxidation polymerization accelerator was dissolved in saturated fatty acid triglyceride (manufactured by NOF Corporation, trade name “Panasate 800”) was added to the oxidation polymerization accelerator supply unit. The content of cobalt octylate in the oxidative polymerization accelerator-containing liquid was 1 wt%.

(Comparative Example 1)
Fixing was performed in the same manner as in Example 1 except that the oxidation polymerization agent applying means was not used and no oxidation polymerization accelerator was applied on the fixing roller.
(Comparative Example 2)
Fixing was performed in the same manner as in Example 6 except that the oxidation polymerization agent applying means was not used and no oxidation polymerization accelerator was applied on the fixing roller.
(Comparative Example 3)
Fixing was performed in the same manner as in Example 1 except that the liquid developer C obtained as described above was used as the liquid developer.

[3] Fixing strength The fixing toner image on the recording medium obtained in each of the above examples and each comparative example was erased with an eraser (made by Lion Corporation, sand eraser “LION 261-11”) at a pressing load of 1.0 kgf. By rubbing 5 times, the residual ratio of the image density was measured by “X-Rite model 404” manufactured by X-Rite Inc, and evaluated according to the following five criteria.

A: Image density residual ratio is 95% or more.
A: Image density residual ratio is 90% or more and less than 95%.
○: Image density remaining rate is 80% or more and less than 90%.
Δ: Image density remaining rate is 70% or more and less than 80%.
X: Image density remaining rate is less than 70%.

As is apparent from Table 1, those using oxidative polymerization of the insulating liquid were excellent in fixing strength. On the other hand, satisfactory results were not obtained with the liquid developers of the comparative examples.
Further, when the fixing temperature of the fixing device was changed to 140 ° C., 120 ° C., 100 ° C., and 80 ° C. and the fixing strength was evaluated in the same manner as described above, the same results were obtained. This shows that the fixing method and fixing device of the present invention are suitable for low-temperature fixing.
Further, when the recording medium conveyance speed of the fixing device was increased from 200 mm / second to 250 mm / second and 300 mm / second and the fixing strength was evaluated in the same manner as described above, the same result was obtained. This shows that the fixing method and fixing device of the present invention are suitable for high-speed printing.

1 is a cross-sectional view illustrating a first embodiment of a fixing device of the present invention. 1 is a cross-sectional view illustrating an example of a contact-type image forming apparatus. 1 is a cross-sectional view illustrating an example of a non-contact image forming apparatus. FIG. 6 is a cross-sectional view illustrating a second embodiment of the fixing device of the present invention. It is sectional drawing which shows other embodiment of the fixing device of this invention.

Explanation of symbols

  F40, F40 '... Fusing device F1 ... Heat fixing roller (heating roller) F1a ... Column-shaped halogen lamp F1b ... Roller base material F1c ... Elastic body F11 ... Oxidation polymerization accelerator removing blade F2 ... Pressure roller F2a ... Rotating shaft F2b ... Roller Substrate F2c ... elastic body F3 ... heat-resistant belt F4 ... belt stretching member F4a ... projection wall F4f ... concave F5 ... recording medium F5a ... unfixed toner image F6 ... cleaning member F7 ... frame F8 ... oxidation polymerization accelerator applying roller F8 ' ... Oxidation polymerization accelerator application brush F81... Oxidation polymerization accelerator supply unit F9... Spring P1... Image forming apparatus P2... Photoconductor P3 ... Charger P4 ... Exposure P10 ... Developer P11 ... Developer container P12. Roller P14 ... Liquid developer coating layer P15 ... Metering blade P16 ... roller core P17 ... developing roller cleaning blade P18 ... intermediate transfer roller P181 ... adjustment roller P19 ... secondary transfer roller P21 ... neutralizing light P22 ... cleaning blade P23 ... cleaning blade P24 ... charging blade

Claims (11)

The formed image on a recording medium body using a liquid developer comprising an insulating liquid and toner particles comprising an unsaturated fatty acid component, a fixing method for fixing on the recording medium body by a fixing roller,
An application step of applying an oxidative polymerization accelerator for accelerating the oxidative polymerization reaction of the unsaturated fatty acid component to the fixing roller surface ;
In the fixing step, and the unsaturated fatty acid component contained in the image, the fixing roller is brought into contact with the granted the oxidation polymerization accelerator, and a fixing step of fixing the image on the recording medium body,
Fixing method which is characterized in that have a.   The fixing method according to claim 1, wherein the oxidative polymerization accelerator is a fatty acid metal salt. The oxidation polymerization accelerator, a fixing method according to the oxidation polymerization accelerator to claim 1 or 2 is dispersed or dissolved in an inert liquid. The inert liquid is the oxidation polymerization accelerator, a fixing method according to claim 3, wherein the fat having saturated fatty acid component. The temperature of the fixing roller, the fixing method according to any one of claims 1 to 4 is 80 to 200 ° C.. A fixing roller;
Wherein the fixing low la, the fixing device characterized in that it comprises the oxidation polymerization accelerator imparting unit that imparts oxidation polymerization accelerator, a. The fixing device according to claim 6, further comprising a pressure roller that presses against the fixing roller and applies pressure to the recording medium. The oxidation polymerization accelerator deposition unit includes a fixing device according to claim 6 or 7 is low la. The oxidation polymerization accelerator deposition unit includes a fixing device according to claim 6 or 7 a brush. Wherein the after fixing the image on the recording medium, the fixing device according to any one of claims 6 to 9 with an oxidizing polymerization accelerator removal unit for removing the oxidation polymerization accelerator attached to the fixing low la.   A liquid developer reservoir for storing a liquid developer having an insulating liquid containing an unsaturated fatty acid component and toner particles;
  A developing unit for developing using the liquid developer supplied from the liquid developer storage unit;
  An image carrier;
  A transfer unit for transferring an image developed on the image carrier by the developing unit to a recording medium;
  Fixing roller for fixing the image on the recording medium, a pressure roller for pressing the fixing roller to apply pressure to the recording medium, and an oxidation polymerization accelerator for promoting an oxidation polymerization reaction of the unsaturated fatty acid component A fixing portion having an oxidation polymerization accelerator providing means for providing
An image forming apparatus comprising:

Images