JP2008158484A - Insulating liquid, liquid developer, method for manufacturing liquid developer, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid developer and an insulating liquid that are environmentally benign and contain toner particles having a sufficiently small particle diameter; to provide a method for manufacturing the liquid developer; and to provide an image forming apparatus using the above liquid developer and the insulating liquid. <P>SOLUTION: The insulating liquid used for a liquid developer containing toner particles includes a fatty acid triglyceride and a fatty acid monoester, the fatty acid triglyceride and the fatty acid monoester each containing an unsaturated fatty acid as a fatty acid component thereof, and an alcohol component constituting the fatty acid monoester having an alkyl group having from 1 to 8 carbon atoms. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an insulating liquid, a liquid developer, a method for producing a liquid developer, and an image forming apparatus.

For the developer used for developing the electrostatic latent image formed on the latent image carrier, a dry toner using a toner composed of a material containing a colorant such as a pigment and a binder resin in a dry state; and There is a liquid developer (liquid toner) in which a toner as shown in Patent Document 1 is dispersed in an electrically insulating carrier liquid (insulating liquid).
The method using dry toner handles solid-state toner, so there are advantages in handling, but there are concerns about adverse effects on the human body due to powder, as well as contamination due to scattering of toner, and when toner is dispersed There is a problem with uniformity. Further, the dry toner has a problem that the particles are likely to aggregate and it is difficult to sufficiently reduce the size of the toner particles, and it is difficult to form a toner image with high resolution. In addition, when the size of the toner particles is relatively small, the problem due to the powder as described above becomes more remarkable.

On the other hand, in the method using the liquid developer, the toner particles are effectively prevented from aggregating in the liquid developer, so that it is possible to use fine toner particles, and the binder resin has a low softening point. (Low softening temperature) can be used. As a result, in the method using a liquid developer, fine line image reproducibility is good, gradation reproducibility is good, color reproducibility is excellent, and it is also excellent as a high-speed image forming method. It has characteristics.
However, since the insulating liquid that has been used in conventional liquid developers is mainly composed of petroleum-based hydrocarbons, it adversely affects the environment when, for example, it goes out of an image forming apparatus or the like. There was concern.

  As a method for producing such a liquid developer, generally, a toner material is kneaded and pulverized to form toner particles, and then mixed and dispersed with an insulating liquid to obtain a liquid developer (dry pulverization method). ) Is used. However, in such a method, it is difficult to sufficiently make the toner particle size, and the heat generated during the pulverization makes it easy for the toner particles to be fused together. It was difficult to make it small. On the other hand, a wet pulverization method has been studied in which a toner material is pulverized (or pulverized) in an insulating liquid to obtain a liquid developer in which toner particles are dispersed in the insulating liquid. In such a method, since the liquid used for pulverization (or pulverization) becomes an insulating liquid contained in the final liquid developer, the toner material is finally removed in the liquid that needs to be distilled off. The manufacturing cost can be reduced as compared with a method of obtaining toner particles by pulverization and pulverization. However, in such a method, a sufficiently small particle size (specifically, a particle size of 3 μm or less is required due to the affinity between the resin material constituting the toner particles and the insulating liquid and the influence of the viscosity of the insulating liquid. It was difficult to obtain toner particles having a diameter).

JP 7-152256 A

  An object of the present invention is to provide a liquid developer and an insulating liquid which are environmentally friendly and have sufficiently small toner particles, and provide a method for producing such a liquid developer. An object of the present invention is to provide an image forming apparatus using such a liquid developer and insulating liquid.

Such an object is achieved by the present invention described below.
The insulating liquid of the present invention is an insulating liquid used for a liquid developer containing toner particles,
Containing fatty acid triglycerides and fatty acid monoesters,
The fatty acid triglyceride and the fatty acid monoester contain an unsaturated fatty acid as a fatty acid component,
The alcohol component constituting the fatty acid monoester has an alkyl group having 1 to 8 carbon atoms.

In the insulating liquid of the present invention, the alcohol component preferably has a linear alkyl group having 1 to 7 carbon atoms.
In the insulating liquid of the present invention, the alcohol component preferably has a branched alkyl group having 3 to 8 carbon atoms.
In the insulating liquid of the present invention, the fatty acid monoester preferably contains a product produced by a transesterification reaction between natural fats and oils and a secondary alcohol or tertiary alcohol.
In the insulating liquid of the present invention, the fatty acid monoester preferably contains an unsaturated fatty acid having 14 to 22 carbon atoms as a fatty acid component.
In the insulating liquid of the present invention, when the content of the fatty acid triglyceride in the insulating liquid is X [wt%] and the content of the fatty acid monoester is Y [wt%], 1 ≦ X / Y ≦ 19 It is preferable to satisfy this relationship.

The insulating liquid of the present invention preferably contains a hydrolysis inhibitor having a function of suppressing hydrolysis of the fatty acid triglyceride and the fatty acid monoester.
In the insulating liquid of the present invention, the content of the hydrolysis inhibitor in the insulating liquid is preferably 0.01 to 5.0 wt%.
In the insulating liquid of the present invention, the hydrolysis inhibitor is preferably a phenol phosphite compound.

The liquid developer of the present invention has toner particles mainly composed of a resin material and an insulating liquid, and the insulating liquid contains a fatty acid triglyceride and a fatty acid monoester, and the fatty acid triglyceride and the fatty acid monoester. The ester contains an unsaturated fatty acid as a fatty acid component, and the alcohol component constituting the fatty acid monoester has an alkyl group having 1 to 8 carbon atoms.
In the liquid developer of the present invention, the acid value of the resin material constituting the toner particles is preferably 0.1 to 15 mgKOH / g.

  The method for producing a liquid developer of the present invention comprises toner particles containing a fatty acid triglyceride and a fatty acid monoester, wherein the fatty acid triglyceride and the fatty acid monoester contain an unsaturated fatty acid as a fatty acid component, and the fatty acid The alcohol component constituting the monoester is characterized by being pulverized and / or pulverized in an insulating liquid having an alkyl group having 1 to 8 carbon atoms.

An image forming apparatus of the present invention includes a liquid developer storage unit that stores a liquid developer,
A developing unit for developing using the liquid developer supplied from the liquid developer storage unit;
A transfer unit that transfers the image formed by the developing unit onto a recording medium and forms a transfer image;
A collecting unit for collecting the liquid developer remaining in the developing unit and / or the transfer unit;
A transport unit configured to transport the liquid developer recovered from the recovery unit to the liquid developer storage unit;
A fixing unit for fixing the transfer image formed on the recording medium onto the recording medium,
The liquid developer includes toner particles mainly composed of a resin material, and an insulating liquid. The insulating liquid includes a fatty acid triglyceride and a fatty acid monoester, and the fatty acid triglyceride and the fatty acid monoester are The fatty acid component contains an unsaturated fatty acid, and the alcohol component constituting the fatty acid monoester has an alkyl group having 1 to 8 carbon atoms.
In the image forming apparatus of the present invention, it is preferable that the image forming apparatus has an insulating liquid replenishing section that replenishes the liquid developer storing section with the insulating liquid of the present invention.

  By satisfying the above configuration, it is possible to provide an environment-friendly liquid developer and an insulating liquid having sufficiently small toner particles. In addition, a method for producing such a liquid developer can be provided. In addition, an image forming apparatus using the liquid developer and the insulating liquid can be provided.

Hereinafter, preferred embodiments of the present invention will be described in detail.
<Liquid developer>
First, the insulating liquid and liquid developer of the present invention will be described.
The liquid developer of the present invention is one in which toner particles are dispersed in an insulating liquid.
<Insulating liquid>
First, the insulating liquid will be described.
The insulating liquid of the present invention contains a fatty acid triglyceride and a fatty acid monoester having an unsaturated fatty acid as a fatty acid component. In the present specification, the unsaturated fatty acid triglyceride means a fatty acid triglyceride having at least one unsaturated fatty acid in the molecular structure as a fatty acid component.

By the way, in the conventional liquid developer, the insulating liquid leaks out of the image forming apparatus during use (for example, volatilization of the insulating liquid during fixing) or the used liquid developer is discarded. There were concerns about the environmental impact of the liquid. Further, the conventional liquid developer has a problem that the fixing property of the toner particles to the recording medium is hindered (fixing strength is reduced) due to the presence of the insulating liquid adhering to the surface of the toner particles.
In contrast, fatty acid triglycerides and fatty acid monoesters used in the insulating liquid of the present invention are both environmentally friendly components. 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 image forming apparatus and disposal of the used liquid developer. As a result, an environmentally friendly liquid developer can be provided.

  Further, the fatty acid triglyceride and the fatty acid monoester contain an unsaturated fatty acid component. This unsaturated fatty acid component is a component that can contribute to improving the fixability of toner particles to a recording medium. More specifically, since the unsaturated fatty acid component is oxidized (by being oxidized at the time of fixing), the polymerization reaction proceeds, and itself is cured, so that the recording medium and the cured liquid developer The fixing effect of the toner particles can be improved by the anchor effect. As a result, according to the present invention, the fixing characteristics of the toner particles to the recording medium can be improved. 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, the fatty acid monoester contained in the insulating liquid penetrates into the resin particles (toner particles) in the fixing process, and exhibits a plasticizer effect. Due to this plasticizer effect, for example, when paper is used as the recording medium, the toner particles can easily enter the gaps between the paper fibers, so that the fixing strength of the toner particles can be increased. Further, the toner particles can be fixed at a lower temperature due to the plasticizer effect.

  Further, by including both the fatty acid triglyceride and the fatty acid monoester in the insulating liquid, the toner particles are prevented from aggregating during storage, and the storage stability and long-term stability are excellent. At the time of fixing, the fixing strength of the toner particles to the recording medium can be made excellent. This can be explained as follows. That is, the fatty acid triglyceride and the fatty acid monoester contained in the insulating liquid are excellent in affinity with a resin material that is a main component of toner particles as described later. Therefore, the dispersibility of the toner particles in the insulating liquid is good, and during storage, the aggregation (blocking) of the toner particles is effectively prevented, and the storage stability and long-term stability of the liquid developer are It will be excellent. On the other hand, at the time of fixing, heat is applied to the liquid developer, whereby the fatty acid monoester penetrates into the toner particles, and the plasticizer effect as described above is exhibited. Thereby, the toner particles can be firmly fixed on the recording medium.

Further, by using an insulating liquid containing a fatty acid triglyceride and a fatty acid monoester as in the present invention, the toner particles can be fixed to the recording medium at a low temperature and exhibit particularly excellent fixing strength. This can be explained as follows. In general, among fatty acid triglycerides and fatty acid monoesters, fatty acid monoesters have a lower viscosity. Furthermore, by including both fatty acid triglycerides and fatty acid monoesters in the insulating liquid, both the insulating liquid and the liquid developer can have appropriate viscosity, and the liquid developer can penetrate into the recording medium. It can be made suitable. Furthermore, since the insulating liquid is cured in a state containing the toner particles due to the oxidative polymerization reaction of the unsaturated fatty acid component in the insulating liquid, the toner particles are separated by the anchor effect between the hardened liquid developer and the recording medium. It can be firmly fixed on a recording medium.
Moreover, the fatty acid monoester which comprises the insulating liquid of this invention has a C1-C8 alkyl group as an alcohol component.

  As a method for producing such a liquid developer, a liquid developer in which toner material (composition constituting toner particles) is pulverized or disintegrated in an insulating liquid and the toner particles are dispersed in the insulating liquid is used. The method of obtaining is being studied. In such a method, since the toner material is pulverized and pulverized in a liquid, generation of heat during pulverization and pulverization can be suppressed, and the pulverized and pulverized toner particles are aggregated and fused. Can be prevented. In addition, since the liquid used for pulverization and pulverization becomes the insulating liquid contained in the final liquid developer, the toner material is pulverized and pulverized in the liquid that needs to be finally distilled off. Compared with the method of obtaining toner particles, the manufacturing cost can be reduced. However, in such a method, it is difficult to sufficiently reduce the size of the toner particles obtained due to the affinity between the insulating liquid and the resin material constituting the toner particles and the influence of the viscosity of the insulating liquid. It was. For example, an aliphatic hydrocarbon-based liquid that has been widely used as an insulating liquid contained in a liquid developer conventionally has a poor affinity with a resin material constituting toner particles. In such a liquid, even if the toner material is suitably pulverized and pulverized, the pulverized and pulverized particles are likely to aggregate together, and as a result, sufficiently small toner particles cannot be obtained. There was a problem.

  On the other hand, a fatty acid monoester having an alkyl group having 1 to 8 carbon atoms as an alcohol component is a component particularly excellent in affinity with a resin material constituting toner particles as described later. Therefore, when the toner material is pulverized and pulverized in the insulating liquid containing such components, aggregation of the pulverized and pulverized particles is surely suppressed. An insulating liquid containing a fatty acid monoester that satisfies the above conditions and a fatty acid triglyceride has an appropriate viscosity and is a component that is particularly easily compatible with toner particles. Thus, the toner material can be suitably pulverized and pulverized during pulverization and pulverization. As a result, the toner material can be suitably pulverized and pulverized in the insulating liquid, and aggregation of the pulverized and pulverized particles is surely prevented, so that the obtained toner particles have a sufficiently small particle size. Can be. In addition, the liquid developer thus obtained sufficiently satisfies the demand for high resolution.

The excellent effect as described above is an effect obtained by including a fatty acid triglyceride and a fatty acid monoester having an alkyl group having 1 to 8 carbon atoms as an alcohol component in the insulating liquid. On the other hand, even if either the fatty acid triglyceride or the fatty acid monoester having the above characteristics is missing in the insulating liquid, the effect of the present invention cannot be obtained. That is, when fatty acid triglyceride is not contained in the insulating liquid, when the toner material is pulverized and pulverized, a low molecular weight and low viscosity fatty acid monoester is contained in the resin material constituting the toner material. It becomes easy to permeate, and the pulverized and crushed particles tend to aggregate. As a result, it becomes impossible to reduce the particle size of the obtained toner particles, and the liquid developer contains coarse particles. In addition, when the fatty acid monoester having the above characteristics is not contained in the insulating liquid, the viscosity of the insulating liquid is increased and the toner material is suitably pulverized and crushed in the insulating liquid. A sufficient affinity between the toner material and the insulating liquid cannot be maintained. As a result, the toner material cannot be suitably pulverized and crushed, and a liquid developer having sufficiently small toner particles cannot be obtained. Further, even when the insulating liquid contains a fatty acid monoester, when the fatty acid monoester contains only a fatty acid monoester having an alkyl group having 9 or more carbon atoms, the viscosity of the insulating liquid Becomes high, and it becomes difficult to suitably pulverize and disintegrate the toner material.
Thus, in the liquid developer of the present invention, the insulating liquid contains a fatty acid monoester having an alkyl group having 1 to 8 carbon atoms as an alcohol component. Among the fatty acid monoesters satisfying the above conditions, When the alkyl group satisfies the following conditions, the following effects can be obtained in addition to the effects described above.

That is, when the fatty acid monoester constituting the insulating liquid has a linear alkyl group having 1 to 7 carbon atoms as an alcohol component, heat is applied during fixing to the toner particles. The fatty acid monoester permeates rapidly and exhibits a plasticizer effect. Accordingly, it can be suitably used for high-speed image formation in which it is desired to fix the toner particles to the recording medium in a short time, and the fixing strength can be made particularly excellent.
Furthermore, as an insulating liquid, in addition to fatty acid triglycerides and fatty acid monoesters having the characteristics as described above, a hydrolysis inhibitor as described later is included, so that the storage stability of liquid developer, long-term stability, Both the fixing property and the fixing property can be made particularly excellent. This can be explained as follows.

That is, the fatty acid monoester having a linear alkyl group as an alcohol component, including the fatty acid monoester having the characteristics as described above, contains moisture present in the air or a slight amount of moisture contained in the insulating liquid. It reacts (hydrolyzes) and is easily decomposed into fatty acid and alcohol. If the liquid developer contains a large amount of the fatty acid thus decomposed (free fatty acid), the free fatty acid penetrates into the toner particles even during storage. As a result, unintentional aggregation of toner particles is caused, and it becomes difficult to obtain sufficiently satisfactory storage stability and long-term stability as a liquid developer. Furthermore, the insulating liquid containing excessive free fatty acids has a poor electrical insulating property, and toner particles are not attached to the electrostatic latent image when developed using an image forming apparatus as described later. It becomes insufficient, and it becomes difficult to obtain a high-definition and high-quality toner image. On the other hand, by including a hydrolysis inhibitor as described later as the insulating liquid, it is possible to suitably suppress the amount of free fatty acids generated in the insulating liquid, and as a result, the liquid developer All of storage stability, long-term stability, and fixing characteristics are particularly excellent.
Moreover, the following effects can be acquired when the fatty acid monoester which comprises an insulating liquid has a C3-C8 linear alkyl group as an alcohol component.

That is, as described above, the fatty acid monoester having a linear alkyl group as the alcohol component is a component that reacts (hydrolyzes) with moisture contained in the insulating liquid to generate free fatty acids. On the other hand, the fatty acid monoester having a branched alkyl group having 3 to 8 carbon atoms as an alcohol component surely exhibits the plasticizer effect as described above at the time of fixing, and the branched alkyl group has steric hindrance. Thus, water molecules are unlikely to approach the ester bond portion of the fatty acid monoester, and hydrolysis of the fatty acid monoester is suppressed. Thereby, the generation amount of the free fatty acid in the insulating liquid can be suitably suppressed over a long period of time. Therefore, by using a combination of such a fatty acid monoester and a fatty acid triglyceride as the insulating liquid constituting the liquid developer, all of the storage stability, long-term stability, and fixing characteristics of the liquid developer are obtained. Is particularly excellent.
The content of fatty acid triglyceride in such an insulating liquid is preferably 55 to 95 wt%, and more preferably 57 to 90 wt%. A liquid developer containing an insulating liquid that satisfies the above conditions is particularly excellent in storage stability and long-term stability.

  Moreover, it is preferable that content of the fatty acid monoester in such an insulating liquid is 5-45 wt%, and it is more preferable that it is 10-43 wt%. As a result, the penetration of the fatty acid monoester into the toner particles at the time of fixing is further improved, and the plasticizer effect is surely exhibited. Thereby, the fixing property of the toner particles to the recording medium can be made particularly excellent.

  Moreover, the ratio of the fatty acid triglyceride and the fatty acid monoester having the above characteristics in the insulating liquid is not particularly limited, but it is preferable that the following relationship is satisfied. That is, when the content of fatty acid triglyceride in the insulating liquid is X [wt%] and the content of the fatty acid monoester in the insulating liquid is Y [wt%], the relationship 1 ≦ X / Y ≦ 19 is satisfied. It is preferable that the relationship is satisfied, and it is more preferable that the relationship of 1.4 ≦ X / Y ≦ 9 is satisfied. As a result, during storage, the fatty acid monoesters are preferably prevented from penetrating into the toner particles, while at the time of fixing, the fatty acid monoesters are sufficiently penetrated into the toner particles to reliably exhibit a plasticizer effect. Can do. As a result, the storage stability and long-term stability of the liquid developer, and the fixing characteristics of the toner particles to the recording medium are further improved.

  Moreover, it is preferable that the acid value of such an insulating liquid is 0.01-1.0 mgKOH / g, and it is more preferable that it is 0.02-0.5 mgKOH / g. As a result, the storage stability and long-term stability of the liquid developer are particularly excellent. In the liquid developer manufacturing method as described later, the material constituting the toner is pulverized or pulverized together with the fatty acid monoester and the fatty acid triglyceride as described above. At this time, since the toner material can be pulverized or crushed more efficiently by using an insulating liquid that satisfies the above conditions, the production time of the toner particles can be shortened and obtained. The particle diameter of the toner particles can be made more uniform.

[Fatty acid triglyceride]
In the present invention, the fatty acid triglyceride in the insulating liquid is a triester (triglyceride) between a fatty acid and glycerin, and contains an unsaturated fatty acid as a fatty acid component.
When the fatty acid triglyceride in the insulating liquid contains an unsaturated fatty acid as the fatty acid component, the toner particles can be firmly fixed on the recording medium while the liquid developer has excellent storage stability and long-term stability. . Examples of such unsaturated fatty acid components include monovalent unsaturated fatty acids such as oleic acid, palmitoleic acid, myristoleic acid, linoleic acid, α-linolenic acid, γ-linolenic acid, arachidonic acid, docosahexaenoic acid ( DHA), eicosapentaenoic acid (EPA), and the like, polyvalent unsaturated fatty acids having a plurality of double bonds in the molecule, and conjugated unsaturated fatty acids thereof.

  Among the unsaturated fatty acid components described above, monovalent unsaturated fatty acids have particularly excellent chemical stability. Therefore, when the fatty acid triglyceride in the insulating liquid contains a monovalent unsaturated fatty acid as the fatty acid component, the storage stability and long-term stability of the liquid developer are particularly excellent. On the other hand, polyunsaturated fatty acids are components having higher reactivity (oxidation reactivity) than monovalent unsaturated fatty acids. Therefore, when the fatty acid triglyceride in the insulating liquid contains a polyunsaturated fatty acid as the fatty acid component, the oxidative polymerization reaction of the insulating liquid at the time of fixing suitably proceeds, and the toner particles are separated from the recording medium. It can be firmly fixed.

  In addition, when fatty acid triglyceride contains saturated fatty acid in addition to unsaturated fatty acid as a fatty acid component, the chemical stability and electrical insulation of the liquid developer can be kept high. And the electrical resistance can be kept high, and the storage stability and long-term stability of the liquid developer can be improved. Examples of such saturated fatty acids include butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid.

  Fatty acid triglycerides as described above are, for example, plant-derived oils such as soybean oil, rapeseed oil, safflower oil, sunflower oil, linseed oil, olive oil, corn oil, coconut oil, cottonseed oil, dehydrated castor oil, palm kernel oil, coconut oil, It can be efficiently obtained by purifying naturally-derived fats and oils such as animal-derived fats and oils such as herring oil and sardine oil. Examples of the purification method include a method in which unrefined fats and oils are mixed with boiled water, and after the mixed solution is completely separated into three layers, components to be frozen in the freezer are removed. Moreover, fatty acid triglyceride with higher purity can be obtained by repeating this method.

The fatty acid triglyceride preferably contains 5 to 80 mol%, more preferably 15 to 80 mol% of a monovalent unsaturated fatty acid with respect to all fatty acid components constituting the fatty acid triglyceride. As a result, the storage stability and long-term stability of the liquid developer can be made particularly excellent.
In addition, the fatty acid triglyceride preferably contains 15 to 80 mol% of polyunsaturated fatty acid, more preferably 20 to 70 mol%, based on all fatty acid components constituting the fatty acid triglyceride. Thereby, the toner particles can be firmly fixed on the recording medium.
In addition, the fatty acid triglyceride preferably contains 5 to 20 mol%, more preferably 10 to 18 mol% of a saturated fatty acid component with respect to all fatty acid components constituting the fatty acid triglyceride. As a result, the storage stability and long-term stability of the liquid developer can be made particularly excellent.

[Fatty acid monoester]
In the present invention, the fatty acid monoester in the insulating liquid is a monoester between a fatty acid and a monohydric alcohol, and contains an unsaturated fatty acid as a fatty acid component.
Such a fatty acid monoester preferably contains an unsaturated fatty acid having 14 to 22 carbon atoms as the fatty acid component. As a result, the unsaturated fatty acid monoester permeates into the toner particles at the time of fixing more suitably, and the effect as a plasticizer is sufficiently exhibited. Further, the penetration of the insulating liquid into the recording medium is suitable, and the liquid developer is more suitably cured by the oxidative polymerization reaction. Due to these effects, the fixing characteristics of the toner particles to the recording medium become more excellent. Examples of such unsaturated fatty acid components include monovalent unsaturated fatty acids such as oleic acid, palmitoleic acid, myristoleic acid, linoleic acid, α-linolenic acid, γ-linolenic acid, arachidonic acid, docosahexaenoic acid ( Examples thereof include polyunsaturated fatty acids having a plurality of double bonds in the molecule, such as DHA) and eicosapentaenoic acid (EPA), and conjugated unsaturated fatty acids thereof.

  The fatty acid component of the fatty acid monoester is mainly an unsaturated fatty acid, but may partially contain a saturated fatty acid. As a result, the storage stability and long-term stability of the insulating liquid are further improved. Examples of such saturated fatty acids include butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristylic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid.

  The fatty acid monoester is a monoester between a fatty acid and a monovalent alcohol, but the alcohol component constituting the fatty acid monoester has an alkyl group having 1 to 8 carbon atoms. When the insulating liquid contains the fatty acid monoester having such characteristics and the fatty acid triglyceride described above, the toner material can be suitably pulverized and pulverized in the insulating liquid, and pulverized and pulverized. Aggregation of the particles is reliably prevented, and the toner particles obtained can be sufficiently small in particle size. In addition, the liquid developer thus obtained sufficiently satisfies the demand for high resolution. As an alcohol that becomes an alkyl group having 1 to 8 carbon atoms by transesterification with a natural oil (for example, fatty acid triglyceride), methanol (C1), ethanol (C2), propanol (C3), butanol (C4), Pentanol (C5), hexanol (C6), heptanol (C7), octanol (C8), alcohol which becomes a linear alkyl group by transesterification reaction with natural fats and oils, isopropanol (C3), 2-butanol (C4), Isobutanol (C4), tert-butanol (C4), 2-pentanol (C5), 3-pentanol (C5), 2,2-dimethyl-1-propanol (C5), 2-hexanol (C6), 3- Methyl-3-pentanol (C6), 2,3-dimethyl-2-butanol (C6), 2-he Butanol (C7), 2,4-dimethyl-3-pentanol (C7), 2-octanol (C8), 2-ethyl-1-hexanol (C8), 1,1-diethyl-3-methyl-1-propanol (C8) ) And the like, and alcohols that become branched alkyl groups by transesterification with natural fats and oils can be mentioned, and one or more selected from these can be used in combination.

Among such alcohols, an insulating liquid containing a fatty acid monoester having an alcohol component that becomes a linear alkyl group having 1 to 7 carbon atoms by transesterification with natural fats and oils, By infiltrating the toner particles, a plasticizer effect is suitably exhibited. Thereby, the fixing property of the toner particles to the recording medium can be improved.
Moreover, although the alcohol component which comprises a fatty acid monoester has the linear alkyl group having 1 to 7 carbon atoms, the above-described effects can be obtained. Is more preferably 1 to 5, and still more preferably 1 to 3. Thereby, the effect as described above becomes more remarkable.

  When the insulating liquid contains a fatty acid monoester having an alcohol component that becomes a branched alkyl group having 3 to 8 carbon atoms by transesterification with natural fats and oils among such alcohols, Such effects can be obtained. That is, the amount of free fatty acid generated in the insulating liquid is suitably suppressed over a long period of time, and the storage stability and long-term stability of the liquid developer are excellent. Further, at the time of fixing, such a fatty acid monoester permeates into the toner particles, thereby suitably exhibiting a plasticizer effect. Thereby, the fixing property of the toner particles to the recording medium can be improved.

  Further, when the alcohol component constituting the fatty acid monoester has a branched alkyl group having 3 to 8 carbon atoms, such an alcohol may be a secondary alcohol or a tertiary alcohol. preferable. Thereby, generation | occurrence | production of a free fatty acid in an insulating liquid can be suppressed more suitably, and the preservability and long-term stability of a liquid developer become further excellent. This is considered to be due to the following reasons. The alcohol component of the fatty acid monoester produced by transesterification of a secondary alcohol or tertiary alcohol with a fatty acid has two or three alkyl groups bonded to the carbon closest to the ester bond. It has a structure. A branched alkyl group having such a structure is a linear alkyl group in which only one alkyl group is bonded to the carbon closest to the ester bond (generated by a transesterification reaction between a fatty acid and a primary alcohol). Compared to the alcohol component of the fatty acid monoester, the steric hindrance around the ester bond is increased, and water molecules and the like can be more effectively suppressed from approaching the ester bond. For this reason, it is thought that the effect as mentioned above can be acquired.

Moreover, although the alcohol component which comprises a fatty acid monoester has the branched alkyl group having 3 to 8 carbon atoms, the effects as described above can be obtained. 3 to 5 is more preferable. Thereby, the effect as described above becomes more remarkable.
Moreover, it is preferable that the fatty acid monoester which comprises an insulating liquid is produced | generated by transesterification with the fatty acid triglyceride mentioned above and C1-C8 monohydric alkyl alcohol. Thereby, the toner particles in the liquid developer can be sufficiently reduced in particle size.

Moreover, it is preferable to contain 10-75 wt% of the fatty acid monoester comprised by the monovalent unsaturated fatty acid as a fatty acid component in all the fatty acid monoesters, and it is more preferable to contain 15-65 wt%. As a result, the storage stability and long-term stability of the liquid developer can be made particularly excellent.
Moreover, it is preferable that 15-80 wt% of the fatty acid monoester comprised by the polyunsaturated fatty acid is included as a fatty-acid component in all the fatty acid monoesters, and it is more preferable that 20-70 wt% is included. Thereby, the toner particles can be firmly fixed on the recording medium.
Moreover, it is preferable that 5-20 wt% of the fatty acid monoester comprised by the saturated fatty acid is included as a fatty-acid component in all the fatty acid monoesters, and it is more preferable that 10-18 wt% is included. As a result, the storage stability and long-term stability of the liquid developer can be made particularly excellent.

The insulating liquid may contain a hydrolysis inhibitor having a function of suppressing hydrolysis of fatty acid triglycerides and fatty acid monoesters.
By including such a hydrolysis inhibitor as a component constituting the insulating liquid, it is possible to effectively suppress the generation of free fatty acids from fatty acid triglycerides and fatty acid monoesters. As a result, the toner particles are excellently fixed on the recording medium, and the toner particles are prevented from unintentionally agglomerating during storage, so that the storage stability and long-term stability of the liquid developer are excellent.

  Examples of the function of such a hydrolysis inhibitor include inhibition of hydrolysis reaction of fatty acid triglyceride and fatty acid monoester, termination, delay, etc., recombination of a cleaved ester bond, etc. What is necessary is just to have a function which suppresses the production amount of a hydrolysis product (free fatty acid and alcohol). Such hydrolysis inhibitors include 2,6-di-tert-butyl-p-cresol, pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, hexamethylene bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], benzenepropanoic acid, 3 , 5-bis (1,1-dimethyl-ethyl) -4-hydroxy-, C7-C9 side chain alkyl ester and other phenol compounds, thiodiethylene bis [3- (3,5-tert-butyl-4-hydroxy Phenyl) propionate] and the like, N-phenyl-1,1,3,3-tetramethyl Butylnaphthalen-1-amine, reaction product of N-phenylbenzene and 2,4,4-trimethylpentene, aromatic amine compounds such as N-isopropyl-N′phenyl-p-phenylenediamine, triphenyl phosphite Tris (biphenyl-2-yl) phosphite, tris (biphenyl-4-yl) phosphite, tris (2-cyclohexylphenyl) phosphite, diphenyl phosphite, cyclic neopentanetetraylbis (2, 6-di-t-butyl-4-methylphenyl) phosphite, irgaphos 168, tris (2,5-di-t-butyl-4-hydroxyphenyl) phosphite, tetrakis [O- (phenyltridecyl phosphite) Methyl] methane, tris (4-nonylphenyl) phosphite, tris (2,4-di-tert-butyl) Ruphenyl) phosphite, bis (nonylphenyl) (biphenyl-2-yl) phosphite, tris (α-methylbenzylphenyl) phosphite, bis (cyclohexylphenyl) phosphite, tetraalkyl-4,4′-butylidenebis (2 -T-butyl-5-methylphenyl) diphosphite, phosphite tris (2,4-di-tert-butylphenyl) = irgaphos 168, phosphite tris (2,5-di-tert-butyl-4-hydroxy) Phenyl), diphenylalkyl (C = 12-20) phosphite, tris phosphite (2,5-di-tert-butyl-4-hydroxyphenyl), [dialkyl (C = 8-18) bis [alkyl (C = 8-18) phenyl]], or tetraalkyl (C = 8-18) 4,4'-isopropyl Pyridene dicyclohexyl diphosphite, alkyl (C = 8-12) [or alkyl (C = 8-12) phenyl] cyclohexyl phenyl phosphite, di (or mono) isopropylbenzyl mono (or di) phenyl phosphite, di (Or mono) (isopropylbenzyl) mono (or di) phenyl phosphite, diphenylisoalkyl (C = 17-25) phosphite, hexaalkyl or [trialkyl (C = 8-18) tris (alkyl (C = 8 , 9) phenyl)] 1,1,3-tris (3-tert-butyl-6-methyl-4-oxyphenyl) -3-methylpropane triphosphite, tetra (2nonylphenyl) diisopropylene glycol diphosphite Tetra (3-noniphenyl) diisopropylene glycol difo Phenol phosphite compounds such as phyte, tetra (4-nonylphenyl) diisopropylene glycol diphosphite, di (lauroxyethyl) phenyl phosphite, N, N′dicyclohexylcarbodiimide (DCC), N, N′-diisopropyl Examples thereof include compounds having a carbodiimide group such as carbodiimide and N-ethyl-N ′-(3-dimethylaminoprolyl), compounds having an acyl group and an isocyanate group, and tocopherols.

  As the hydrolysis inhibitor contained in the insulating liquid, one or two or more of the above-mentioned compounds can be used in combination. Among these compounds, phenol is used as the hydrolysis inhibitor. It is preferable to use a phosphite compound. By containing such a hydrolysis inhibitor in the insulating liquid, an appropriate amount of free fatty acid should be present in the insulating liquid while suppressing the generation of free fatty acids from fatty acid triglycerides and fatty acid monoesters. Can do. In the liquid developer using such an insulating liquid, the storage property and long-term stability of the liquid developer can be improved, and the fixing characteristics of the toner particles to the recording medium can be further improved. . Furthermore, the odor generated from the fatty acid triglyceride and fatty acid monoester generated during fixing can be more effectively prevented. The above effect is considered to be obtained for the reasons described below.

  That is, during storage, the amount of free fatty acid in the insulating liquid is an appropriate amount, so such free fatty acid does not adversely affect the liquid developer, and the storage stability and long-term stability of the liquid developer are It will be excellent enough. On the other hand, at the time of fixing, the free fatty acid penetrates into the toner particles together with the fatty acid monoester. Such a free fatty acid has a lower molecular weight than the fatty acid monoester before being decomposed, and is excellent in permeability to toner particles. Therefore, compared to an insulating liquid containing no free fatty acid, an insulating liquid containing an appropriate amount of free fatty acid strongly develops a plasticizer effect on the toner particles and can quickly fix the toner particles on the recording medium. Therefore, it can be suitably used for image formation.

  Furthermore, at the time of fixing, heat is applied to the liquid developer, but this heat weakens the function of the phenol phosphite compound to suppress hydrolysis, and fatty acid triglycerides and fatty acid monoesters are fatty acids (free fatty acids). It is thought that it is easily decomposed into alcohol. As described above, the free fatty acid generated in the insulating liquid at the time of fixing promotes the plasticizer effect on the toner particles and can firmly fix the toner particles on the recording medium. Furthermore, such free fatty acids are components that have a high affinity and reactivity with the paper constituent material (cellulose), which is a recording medium. This free fatty acid is considered to react with a hydroxyl group of cellulose to form an ester bond. Since the ester-bonded free fatty acid does not volatilize, the fixing characteristics can be made particularly excellent, and as a result, the components of the insulating liquid that volatilizes during fixing can be reduced. It is considered that the discharged odor can be effectively suppressed.

  Furthermore, since the phenol phosphite compound continues to maintain its function as a hydrolysis inhibitor for a long period of time, for example, free fatty acids are contained in the liquid developer even when the storage period of the liquid developer is long. Can be more efficiently prevented from occurring excessively. Thereby, the toner particles can be firmly fixed on the recording medium, and the storage stability and long-term stability of the liquid developer can be made particularly excellent.

  Further, the phenol phosphite compound is generally a transparent or light white compound, and even when used for toner, it hardly affects the color tone of the formed toner image. In addition, the phenol phosphite compound is stable to heat and is not easily broken by heat due to fixing at the time of image formation. For this reason, even after fixing, the phenol phosphite compound does not change due to heat and hardly affects the color tone of the fixed toner image.

  The molecular weight of such a phenol phosphite compound is preferably 173 to 2000, and more preferably 200 to 1500. When the molecular weight of the phenol phosphite compound is in such a range, the phenol phosphite compound has excellent affinity with the insulating liquid, so that the environmental stability of the liquid developer is particularly excellent. Can do.

  Further, among the above-described phenol phosphite compounds, tetraalkyl-4,4′-butylidenebis (2-t-butyl-5-methylphenyl) diphosphite is preferably used, and among the above compounds, tetratridecyl is used. It is more preferable to use -4,4'-butylidenebis (2-t-butyl-5-methylphenyl) diphosphite. Thereby, the effect as described above appears more remarkably.

  Moreover, it is preferable that the content of the hydrolysis inhibitor in such an insulating liquid is 0.01 to 5.0 wt% in the total insulating liquid, and 0.05 to 2.0 wt%. Is more preferable. In the insulating liquid that satisfies the above conditions, the generation of free fatty acids from fatty acid triglycerides and fatty acid monoesters as described above can be more effectively suppressed. Accordingly, the storage property and long-term stability of the liquid developer are particularly excellent while the toner particles are excellently fixed on the recording medium.

Further, the liquid developer (insulating liquid) may contain a dispersant that improves the dispersibility of the toner particles.
As such a dispersant, for example, polyvinyl alcohol, carboxymethyl cellulose, polyethylene glycol, Solsperse (trade name of Nippon Lubrizol Co., Ltd.), polycarboxylic acid and its salt, polyacrylic acid metal salt (for example, sodium salt), Polymethacrylic acid metal salt (for example, sodium salt), polymaleic acid metal salt (for example, sodium salt), acrylic acid-maleic acid copolymer metal salt (for example, sodium salt), polystyrene sulfonic acid metal salt (for example, , Sodium salts, etc.), polymer dispersants such as polyamine fatty acid condensation polymers, viscosity minerals, silica, tricalcium phosphate, tristearic acid metal salts (for example, aluminum salts), distearic acid metal salts (for example, aluminum salts, Barium salts), metal stearates (e.g. Calcium salt, lead salt, zinc salt, etc.), linolenic acid metal salt (eg, cobalt salt, manganese salt, lead salt, zinc salt, etc.), octanoic acid metal salt (eg, aluminum salt, calcium salt, cobalt salt, etc.), Oleic acid metal salt (for example, calcium salt, cobalt salt, etc.), palmitic acid metal salt (for example, zinc salt), dodecylbenzenesulfonic acid metal salt (for example, sodium salt), naphthenic acid metal salt (for example, calcium salt) , Cobalt salts, manganese salts, lead salts, zinc salts, etc.), resinic acid metal salts (for example, calcium salts, cobalt salts, manganese lead salts, zinc salts, etc.) and the like.

Among the above-described dispersants, when a polyamine fatty acid condensation polymer is used, the polyamine fatty acid condensation polymer can be attached to the surface of the toner particles, thereby preventing unintentional aggregation of the toner particles. it can. Further, the permeability of the fatty acid monoester to the toner particles can be increased, and the plasticizer effect by the fatty acid monoester can be made more remarkable. As a result, the toner particles can be more firmly fixed to the recording medium. Further, the charging characteristics of the toner particles can be made higher.
When the polyamine fatty acid condensation polymer is used, the content of the polyamine fatty acid condensation polymer in the liquid developer is preferably 0.5 to 7.5 parts by weight with respect to 100 parts by weight of the toner particles. More preferably, it is ˜5 parts by weight. Thereby, the effect by using a polyamine fatty acid condensation polymer can be made more remarkable.

The liquid developer (insulating liquid) may contain a charge control agent.
Examples of the charge control agent include metal oxides such as zinc oxide, aluminum oxide, and magnesium oxide, metal salts of benzoic acid, metal salts of salicylic acid, metal salts of alkyl salicylic acid, metal salts of catechol, metal-containing bisazo dyes, nigrosine Examples thereof include dyes, tetraphenylborate derivatives, quaternary ammonium salts, alkylpyridinium salts, chlorinated polyesters, and nitrofunnic acid.
The electrical resistance of the insulating liquid as described above at room temperature (20 ° C.) is preferably 1 × 10 ¹² Ωcm or more, and more preferably 7 × 10 ¹² Ωcm or more.
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 (toner material)]
In the liquid developer of the present invention, toner particles are dispersed in the insulating liquid as described above.
The toner particles (toner) constituting the liquid developer of the present invention include at least a 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 this invention, resin (binder resin) is not specifically limited, For example, although well-known resin can be used, it is preferable to use a polyester resin. Like the fatty acid monoester and fatty acid triglyceride described above, the polyester resin has an ester component in the molecular structure, so it has a high affinity with the insulating liquid, and the toner particles are dispersed in the liquid developer. The property can be made particularly excellent. Further, at the time of fixing, the fatty acid monoester easily permeates, and the plasticizer effect as described above can be surely expressed. As a result, aggregation of the toner particles during storage is more effectively prevented, and the storage stability and long-term stability of the liquid developer are particularly excellent, and the fixing characteristics of the toner particles to the recording medium are further improved. It can be excellent. Furthermore, the polyester resin has high transparency, and when used as a binder resin, the color developability of the obtained image can be made high.

  Moreover, it is preferable that the acid value of such resin is 0.1-15 mgKOH / mg, it is more preferable that it is 1-10 mgKOH / mg, and it is further more preferable that it is 3-8 mgKOH / mg. Toner particles made of a resin material that satisfies the above conditions are particularly excellent in affinity with the insulating liquid as described above. Thereby, during storage, the dispersibility of the toner particles in the liquid developer becomes better, and the aggregation of the toner particles can be more efficiently prevented over a long period of time. Further, at the time of fixing, the penetration of the insulating liquid into the toner particles becomes more suitable, the plasticizer effect is expressed more strongly, and the toner particles can be firmly fixed on the recording medium.

  The softening temperature of such a resin (resin material) is not particularly limited, but is preferably 50 to 130 ° C, more preferably 50 to 120 ° C, and further preferably 60 to 115 ° C. preferable. 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. The colorant is not particularly limited, and for example, known pigments and dyes can be used.
3. Other Components The toner may contain components other than those described above. Examples of such components include known waxes and magnetic powders.
In addition to the materials described above, for example, zinc stearate, zinc oxide, cerium oxide, silica, titanium oxide, iron oxide, fatty acid, fatty acid metal salt, and the like are used as toner constituent materials (components). Also good.

[Toner particle shape, etc.]
As the toner particles applied to the liquid developer of the present invention, those having fine irregularities on the surface are preferably used. By having such minute irregularities, the above-mentioned fatty acid monoester can be more effectively unevenly distributed (adsorbed) near the surface of the toner particles.
The average particle size of the toner particles composed of the above materials is preferably 0.1 to 3 μm, more preferably 0.5 to 2.5 μm, and 0.5 to 2.0 μm. More preferably. When the average particle diameter 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. Further, by using the insulating liquid of the present invention, the particle size of the toner particles pulverized and pulverized in the insulating liquid surely has a particle size within the above range. In the present specification, “average particle diameter” refers to an average particle diameter based on volume.

The standard deviation of the particle size between toner particles constituting the liquid developer is preferably 1.0 μm or less, more preferably 0.1 to 1.0 μm, and more preferably 0.1 to 0. More preferably, it is 8 μm. As a result, the variation in characteristics among the toner particles becomes particularly small, and the reliability of the entire liquid developer is further improved.
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 preferably 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 in 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%.

  In addition, the viscosity (the viscosity measured according to JIS Z8809 using a vibration viscometer at 25 ° C.) of the liquid developer (liquid developer of the present invention) composed of each component as described above is 50 to 1000 mPa · s, more preferably 100 to 900 mPa · s, and still more preferably 150 to 800 mPa · s. Thereby, since the penetration of the liquid developer into the recording medium becomes more suitable, the fixing characteristics of the toner particles to the recording medium become more excellent. In addition, the image obtained on the recording medium becomes clear with no unevenness, and is particularly suitable as a liquid developer suitable for image formation at high speed. However, when the fatty acid monoester is not included, the viscosity of the insulating liquid becomes too high, and the toner liquid is fixed on the recording medium in a state where a large amount of the insulating liquid is adhered to the surface of the toner particles. When a large amount of insulating liquid is present on the surface of the toner particles as described above, the insulating liquid having a high viscosity hardly penetrates into the recording medium, so that the fixing characteristics of the toner particles to the recording medium are deteriorated, and the high-speed image is obtained. Formation can also be difficult. Further, the plasticizer effect as described above is not sufficiently exhibited, and excellent fixing characteristics and glossiness of the formed image cannot be obtained. In addition, when the fatty acid triglyceride is not included, the viscosity of the insulating liquid becomes too low. For example, in an image forming apparatus as described later, the liquid developer can be pumped out of the developer container with a coating roller. The toner particles cannot be uniformly fixed on the recording medium, resulting in unevenness in the obtained image, the image density becomes low, and the fixing characteristics of the toner particles to the recording medium. May become insufficient.

Further, the electric resistance of the liquid developer (the liquid developer of the present invention) composed of the above-described components is preferably 1.5 × 10 ¹² Ωcm or more, and 2.0 × 10 ¹² Ωcm or more. It is more preferable that
The insulating liquid as described above can be produced, for example, by mixing the fatty acid triglyceride and the fatty acid monoester as described above. A liquid developer can be produced by mixing such an insulating liquid and toner particles, but can also be produced using the following method.

<< Method for Producing Liquid Developer >>
Next, a preferred embodiment of the method for producing a liquid developer of the present invention will be described.
<First Embodiment>
First, a first embodiment of a method for producing a liquid developer according to the present invention will be described.
In the method for producing a liquid developer according to the present embodiment, in a toner material preparation step for obtaining a toner material composed of a resin material and a colorant, and in a mixed solution of a fatty acid monoester or a fatty acid monoester and a part of a fatty acid triglyceride And a pulverizing step of pulverizing the coarsely pulverized product composed of the toner material to obtain a pulverized product dispersion, and a mixing step of mixing the pulverized product dispersion and fatty acid triglyceride.

[Toner material preparation process]
First, an example of a method for preparing a toner material mainly composed of a resin material will be described.
Such a toner material may be prepared by any method, but in this embodiment, the toner material such as a known resin material and a colorant as described above is kneaded to constitute the toner material. After obtaining the kneaded material, the kneaded material is coarsely pulverized to obtain a coarsely pulverized material composed of the toner material.

  Thus, by kneading the resin material and the colorant, the kneading obtained can be obtained even in the case where the components constituting the toner particles include components that are difficult to disperse or compatible with each other in the pulverization step described later. In the product, each component can be sufficiently dissolved and finely dispersed. As a result, the variation in characteristics among the toner particles can be made sufficiently small. In addition, by kneading the kneaded material composed of the toner material before the pulverization process described later, the particle diameter of the toner particles can be reduced more effectively in the pulverization process.

[Crushing process]
In this step, the constituent material (toner material) of the toner particles as described above is a combination of the fatty acid monoester having the characteristics as described above or the fatty acid monoester having the characteristics as described above and a part of the fatty acid triglyceride. A pulverized dispersion is obtained by wet pulverization in a mixed liquid (hereinafter also referred to as pulverizing fatty acid ester liquid).

  Such a fatty acid ester liquid for pulverization has a relatively low viscosity, and the degree of freedom of movement of the toner material in these liquids is high, so that the coarsely pulverized product can be efficiently pulverized. The fatty acid ester liquid for pulverization has high affinity with the above-mentioned known resin materials and has a relatively low viscosity, so that it can enter into fine cracks of the toner material caused by pulverization or the like. As a result, it can be efficiently pulverized and toner particles having a sufficiently small particle diameter can be efficiently formed. Further, the pulverization rate can be improved. Further, by grinding in a fatty acid ester liquid for pulverization having a relatively low viscosity, the energy applied for pulverization can be efficiently used for pulverizing the toner material, so that the temperature of the fatty acid ester liquid for pulverization rises. Can be prevented. As a result, even if the resin material constituting the toner material has a low melting point, it can be efficiently pulverized.

  In addition, by crushing the toner material in the pulverizing fatty acid ester solution, the fatty acid monoester contained in the pulverizing fatty acid ester solution is unevenly distributed (adsorbed) near the surface of the toner particles in the liquid developer finally obtained. ). Thus, by making the fatty acid monoester unevenly distributed near the surface of the toner particles, the plasticizer effect as described above can be made more remarkable. As a result, the toner particles can easily enter through the gaps in the paper fibers (recording medium), so that the fixing strength of the toner particles can be made particularly excellent.

The method of wet pulverization is not particularly limited, and can be performed using various pulverizers and crushers such as a ball mill, a vibration mill, a jet mill, and a pin mill.
The wet pulverization step may be performed in multiple steps.
Before mixing the pulverizing fatty acid ester solution and the toner material, a dispersant as described above may be added to the pulverizing fatty acid ester solution. As a result, the dispersant acts as a pulverization aid, and the toner material can be pulverized more efficiently and the dispersibility of the resulting toner particles can be made higher.
Further, when the toner material is pulverized in a state where the fatty acid ester liquid for pulverization contains the dispersant, the dispersant easily adheres to the surface of the toner particles, and the charging characteristics of the finally obtained liquid developer Can be improved.

  Among the dispersants described above, when a polyamine fatty acid condensation polymer is used, the pulverization efficiency can be effectively increased. Further, when the polyamine fatty acid polycondensation polymer is present when pulverized with the fatty acid ester liquid for pulverization, the polyamine fatty acid polycondensation polymer can be suitably present (entangled) on the surface of the toner particles. When mixed with triglyceride, the fatty acid monoester can be more effectively retained near the surface of the toner particles. As a result, the dispersibility of the toner particles in the finally obtained liquid developer can be further improved, and the fixing characteristics can be further improved.

[Mixing process]
Next, the obtained pulverized product dispersion and the fatty acid triglyceride are mixed (mixing step).
As described above, the liquid developer of the present invention in which toner particles are dispersed in an insulating liquid containing a fatty acid triglyceride and a fatty acid monoester is obtained.

<Second Embodiment>
Next, a second embodiment of the method for producing a liquid developer according to the present invention will be described.
The method for producing a liquid developer according to the present embodiment includes an association particle forming step of associating resin fine particles mainly composed of a resin material to obtain association particles, a fatty acid monoester, or a part of a fatty acid monoester and a fatty acid triglyceride. In which the associated particles are crushed in a mixed liquid (hereinafter also referred to as a pulverizing fatty acid ester liquid) to obtain a toner particle dispersion in which toner particles are dispersed in the pulverizing fatty acid ester liquid, and the obtained toner A mixing step of mixing the particle dispersion and the fatty acid triglyceride.

[Preparation of associated particles]
First, an example of a method for preparing associated particles in which resin fine particles mainly composed of a resin material are associated will be described.
The association particles may be prepared by any method, but in this embodiment, a dispersoid (fine particles) mainly composed of a resin material (toner material) in an aqueous dispersion medium composed of an aqueous liquid. ) Is dispersed, and the dispersoids in the aqueous emulsion are associated to obtain associated particles.

(Preparation of aqueous dispersion)
Hereinafter, the preparation of the aqueous dispersion will be described.
The aqueous dispersion may be prepared by any method, but in this embodiment, first, the toner material as described above is dissolved in a solvent to obtain a toner material solution, and the toner material solution, By mixing with an aqueous dispersion medium composed of an aqueous liquid, an aqueous emulsion in which the dispersoid (liquid dispersoid) containing the toner material is dispersed is obtained, and then at least one of the solvents contained in the aqueous emulsion is obtained. An aqueous dispersion is obtained by removing the part.

The aqueous emulsion can be prepared, for example, as follows (aqueous emulsion preparation step).
First, an aqueous dispersion medium is prepared.
The aqueous dispersion medium is composed of an aqueous liquid.
In the present invention, the “aqueous liquid” refers to a liquid that is excellent in water and / or water compatibility (for example, a liquid having a solubility in 100 g of water at 25 ° C. of 30 g or more). As described above, the water-based liquid is composed of water and / or a liquid having excellent compatibility with water, but is preferably composed mainly of water. In particular, the water content is 70 wt%. % Or more is preferable, and 90% by weight or more is more preferable. By using such a material, for example, the dispersibility of the dispersoid in the aqueous dispersion medium can be improved, and the dispersoid in the aqueous emulsion can have a relatively small particle size and a variation in size. It can be less. As a result, the toner particles in the finally obtained liquid developer have a small variation in size and shape between the particles, and have a high degree of circularity.

Specific examples of the aqueous liquid include, for example, water, alcohol solvents such as methanol, ethanol and propanol, ether solvents such as 1,4-dioxane and tetrahydrofuran (THF), and aromatic heterocycles such as pyridine, pyrazine and pyrrole. Compound solvents, amide solvents such as N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMA), nitrile solvents such as acetonitrile, and aldehyde solvents such as acetaldehyde.
Further, an emulsifying dispersant may be added to the aqueous dispersion medium as necessary. By adding an emulsifying dispersant, an aqueous emulsion can be prepared more easily.
The emulsifying dispersant is not particularly limited, and for example, a known emulsifying dispersant can be used.

On the other hand, the toner material as described above is dissolved in a solvent to prepare a toner material solution.
Any solvent can be used as long as it dissolves at least a part of the toner material, but it is preferable to use a solvent having a boiling point lower than that of the aqueous liquid described above. Thereby, a solvent can be removed easily.
Moreover, it is preferable that a solvent is a thing with low compatibility with the aqueous dispersion medium (aqueous liquid) mentioned above (for example, a thing with the solubility with respect to 100 g of aqueous dispersion media at 25 degreeC is 30 g or less). Thereby, the toner material can be finely dispersed in a stable state in the aqueous emulsion.
In addition, the composition of the solvent can be appropriately selected according to, for example, the known resin and colorant composition as described above, the composition of the aqueous dispersion medium, and the like.
Such a solvent is not particularly limited, and examples thereof include ketone solvents such as MEK and aromatic hydrocarbon solvents such as toluene.

  In preparing the toner material solution, for example, a kneaded material obtained by kneading a toner material such as a resin material or a colorant may be used. By using such a kneaded product, each component in the kneaded product obtained by kneading can be obtained even when the constituent materials of the toner contain components that are hardly dispersed or compatible with each other. It can be in a sufficiently compatible and finely dispersed state. In particular, when a pigment (colorant) having a relatively low dispersibility in the solvent as described above is used, the resin component or the like is effective around the pigment particles by being kneaded in advance before being dispersed in the solvent. Thus, the dispersibility of the pigment in the solvent is improved (particularly fine dispersion in the solvent is possible), and the color developability of the finally obtained toner is also improved. For this reason, in the case where the constituent material of the toner contains a component that is poor in dispersibility in the aqueous dispersion medium of the aqueous emulsion or a component inferior in solubility in the solvent contained in the dispersion medium of the aqueous emulsion. Even so, the dispersibility of the dispersoid in the aqueous emulsion can be made particularly excellent.

Next, the toner material solution is gradually added dropwise to the stirred aqueous dispersion medium to obtain an aqueous emulsion in which the dispersoid containing the toner material is dispersed in the aqueous dispersion medium. It is done. Note that when the toner material solution is dropped, the aqueous dispersion medium and / or the toner material solution may be heated.
Thereafter, the obtained aqueous emulsion is heated or placed in a reduced-pressure atmosphere to remove at least part of the solvent contained in the dispersoid, and the dispersoid (fine particles) composed of the toner material is dispersed. An aqueous dispersion is obtained.

The content of the dispersoid in the aqueous dispersion is not particularly limited, but is preferably 5 to 55 wt%, and more preferably 10 to 50 wt%. Thereby, the productivity of toner particles (liquid developer) can be made particularly excellent while more surely preventing unintentional aggregation of dispersoids in the aqueous dispersion.
The average particle size of the dispersoid in the aqueous dispersion is not particularly limited, but is preferably 0.01 to 3 μm, and more preferably 0.1 to 2 μm. Thereby, the size of the toner particles finally obtained can be optimized. In the present specification, “average particle diameter” refers to an average particle diameter based on volume.

(Association particle formation process)
Next, an electrolyte is added to the aqueous dispersion obtained as described above, and the dispersoid is associated to form associated particles (associated particle forming step).
Examples of the electrolyte to be added include acidic substances such as hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, and oxalic acid, sodium sulfate, ammonium sulfate, potassium sulfate, magnesium sulfate, sodium phosphate, sodium dihydrogen phosphate, sodium chloride, and chloride. Organic and inorganic water-soluble salts such as potassium, ammonium chloride, calcium chloride, and sodium acetate can be used, and one or more of these can be used in combination. Among these, monovalent cation sulfates such as sodium sulfate and ammonium sulfate can be suitably used for promoting uniform association.
In addition, before adding electrolyte etc., you may add inorganic dispersion stabilizers, such as a hydroxyapatite, and an ionic and nonionic surfactant as a dispersion stabilizer. By adding an electrolyte in the presence of a dispersion stabilizer (emulsifier), non-uniform association can be prevented.

  Examples of such a dispersion stabilizer include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene Examples include ethylene sorbitan fatty acid esters, various pluronic nonionic surfactants, alkyl sulfate salt type anionic surfactants, quaternary ammonium salt type cationic surfactants, and the like. Among these, anionic and nonionic surfactants are effective in dispersion stability even when added in a small amount, and can be suitably used. The cloud point of the nonionic surfactant is preferably 40 ° C. or higher.

The amount of the electrolyte added is preferably 0.5 to 15 parts by weight, more preferably 1 to 12 parts by weight, with respect to 100 parts by weight of the solid content in the aqueous dispersion. More preferably. When the amount of electrolyte added is less than the lower limit, dispersoid association may not proceed sufficiently. Further, when the amount of electrolyte added exceeds the upper limit, dispersoids are not uniformly associated with each other and coarse particles may be generated, and there is a possibility that the size of finally obtained toner particles may vary. is there.
Then, after associating, the associated particles are obtained by filtration, washing, drying and the like.
The average particle size of the obtained associated particles is preferably 0.1 to 7 μm, and more preferably 0.5 to 3 μm. Thereby, the particle diameter of the toner particles finally obtained can be made moderate.

[Crushing process]
Next, the associated particles obtained as described above are crushed in a crushing fatty acid ester solution (pulverization step). As a result, a toner particle dispersion in which toner particles are dispersed in the pulverizing fatty acid ester solution is obtained. Moreover, such a fatty acid ester liquid for crushing contains a fatty acid monoester having the characteristics as described above. As a result, the associated particles can be suitably crushed, and the toner particles obtained can have a sufficiently small particle size.

In addition, the fatty acid contained in the pulverizing fatty acid ester solution in the vicinity of the surface of the toner particles in the liquid developer finally obtained by pulverizing the associated particles in the pulverizing fatty acid ester solution as described above. Monoester can be unevenly distributed (adsorbed). Thus, by making the fatty acid monoester unevenly distributed near the surface of the toner particles, the plasticizer effect as described above can be made more remarkable. As a result, the toner particles can easily enter through the gaps in the paper fibers (recording medium), so that the fixing strength of the toner particles can be made particularly excellent.
Further, since the pulverization is performed in a liquid called a fatty acid ester liquid for pulverization, it is possible to prevent generation of toner particles coarsened due to aggregation or the like.
Further, the obtained toner particles have irregularities derived from the fine particles (dispersoid) on the surface thereof, so that the fatty acid monoester can be reliably retained on the irregularities.

Further, in the present embodiment, toner particles are obtained by crushing the associated particles, so that fine particles (particles extremely smaller than particles of a target size) are obtained as compared with conventional pulverization methods and wet pulverization methods. Generation | occurrence | production can be prevented effectively. As a result, it is possible to effectively prevent a decrease in charging characteristics of the liquid developer due to fine powder.
Further, since the fatty acid ester liquid for crushing has a relatively low viscosity, it easily enters between the fine particles (dispersoids) constituting the associated particles, and can suitably break up the associated particles.

[Mixing process]
Next, the toner particle dispersion obtained as described above and fatty acid triglyceride are mixed to disperse the toner particles in the insulating liquid (mixing step).
As described above, the liquid developer of the present invention in which toner particles are dispersed in an insulating liquid containing a fatty acid triglyceride and a fatty acid monoester is obtained.

≪Image forming device≫
Next, a preferred embodiment of the image forming apparatus to which the liquid developer of the present invention as described above is applied <first embodiment>
First, a first embodiment of an image forming apparatus to which the liquid developer of the present invention is applied will be described.

FIG. 1 is a diagram illustrating an example of a first embodiment of a contact-type image forming apparatus to which a liquid developer of the present invention is applied.
As shown in FIG. 1, the image forming apparatus P100 uses an image (toner image) by using a liquid developer reservoir P1 that stores the liquid developer 1 and the liquid developer 1 stored in the liquid developer reservoir P1. ), A transfer unit P3 that transfers the image formed by the development unit P2 to the recording medium 2, and a development unit liquid collection unit P4 that collects the liquid developer 1 that is no longer needed in the development unit P2. And a transfer part liquid recovery part P5 for recovering the liquid developer 1 that is no longer necessary in the transfer part P3, and the liquid developer 1 recovered by the development part liquid recovery part P4 and the transfer part liquid recovery part P5. The recovered liquid developer transport section (transport section) P6 transported to the storage section P1, the circulation section P7 for circulating the liquid developer 1 in the liquid developer storage section P1, and the liquid developer storage section P1 are stored. Supply replenishment insulating liquid 10 to liquid developer 1 And a sex liquid supply portion P8.

The liquid developer storage part P1 has a function of storing the liquid developer 1 in which toner particles are dispersed in the insulating liquid 10 as described above.
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.

  Further, in such a photoreceptor 10Y, it is preferable that the photosensitive layer is made of a material such as amorphous silicon. Amorphous silicon has a very high hardness compared to a conventional organic photoconductor (OPC) and is excellent in friction resistance. Therefore, it is possible to suitably prevent the surface of the photoreceptor P21 from being damaged by the contact between the surface of the photoreceptor P21 and the toner particles. Furthermore, the deterioration of the member due to the insulating liquid in the liquid developer can be minimized. The photoreceptor P21 having such characteristics has a long life and is suitable for long-term use. In addition, it is excellent in repeated stability of electrical characteristics and environmental resistance (temperature and humidity in use environment), and can maintain the development accuracy on the recording medium for a long time.

  The surface of the photoreceptor P21 is uniformly charged by a charger P211 composed of epichlorohydrin rubber or the like, and then exposed in accordance with information to be recorded by a line head exposure unit P212 composed of an organic EL element 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.

Here, the line head exposure unit P212 will be described with reference to the drawings.
FIG. 2 is a schematic perspective view showing the line head exposure part P212 in an enlarged manner.
The line head exposure unit P212 mounts a light emitting element array P2121 made of organic EL elements on a glass substrate P2122, and is driven by a thin film transistor (TFT) P2127 formed on the same glass substrate P2122. The gradient index rod lens array P2124 constitutes an imaging optical system, and a gradient index rod lens P2124 ′ disposed in front of the light emitting unit is stacked. The housing P2120 covers the periphery of the glass substrate P2122, and the side facing the photoreceptor P21 is open. In this way, the light beam is emitted from the gradient index rod lens P2124 ′ to the photoreceptor P21. A light-absorbing member (paint) is provided on the surface of the housing P2120 that faces the end surface of the glass substrate P2122.

  FIG. 3 is a cross-sectional view of the line head exposure unit P212 in the sub-scanning direction. In the line head exposure part P212, a light emitting element array P2121 made of organic EL elements attached facing the rear surface of the gradient index rod lens array P2124 in the housing P2120, and a sealing member P2123 covering the light emitting element array P2121. And an opaque cover P2125 for shielding the light emitting element array P2121 made of organic EL elements therein from the back surface of the housing P2120.

  Further, the cover P2125 is pressed against the back surface of the housing P2120 by the fixed plate spring P2126, and the inside of the housing P2120 is sealed in a light-tight manner. That is, the glass substrate P2122 is optically sealed by the housing P2120 by the fixed plate spring P2126. For this reason, total reflection at the end face of the glass substrate P2122 can be prevented, and light can be efficiently absorbed. A plurality of fixed leaf springs P2126 are provided in the longitudinal direction of the housing P2120 (not shown in FIG. 3).

  In FIG. 3, the housing P2120 made of an opaque member is made of a material that absorbs light, for example, a synthetic resin such as black polystyrene, anodized aluminum, or the like. Further, a black paint is applied to the thickness direction end faces on both sides of the glass substrate P2122, that is, the surface of the housing P2120 facing the thickness direction end faces in the sub-scanning direction to enhance the light absorption characteristics. Thus, by using an organic EL element as a light emitting element, the light emitting element can be easily manufactured on a glass substrate. Therefore, the shape of the light-emitting element can be made arbitrary, so that the price can be reduced. Further, by using such a line head exposure unit P212 in an image forming apparatus, it is possible to provide an image forming apparatus with little image deterioration even if it is used for a long time.

The liquid supply roller P22 has a function of supplying the liquid developer to the liquid thickness regulating roller P23 by rotating.
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 P60. By this pump P60, 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 to the liquid developer storage part P1.

  In this way, the liquid developer 1 recovered by the developing unit liquid recovery unit P4 and the transfer unit liquid recovery unit P5 is exposed to heat generated by the operating state inside the apparatus. Therefore, in the conventional liquid developer, even if the recovered liquid developer is transported to the liquid developer reservoir, the liquid developer in a deteriorated state is transported, and the liquid developer in the liquid developer reservoir is transported. There was a possibility of deteriorating the storage stability and long-term stability. On the other hand, the insulating liquid constituting the liquid developer 1 of the present invention suppresses hydrolysis of fatty acid triglycerides and fatty acid monoesters even at high temperatures, and the toner particles are preferably aggregated in the liquid developer. Is prevented. Therefore, the liquid developer 1 of the present invention can be suitably used in the image forming apparatus having the recovery unit as described above, and the storage stability and long-term stability of the liquid developer 1 in the liquid developer storage unit P1 are improved. While being able to make it excellent, a liquid developer can be used more wastefully.

Further, the recovered liquid developer transport part P6 has a filtration filter (impurity removing means) P61 as shown in FIG.
The filtration filter P61 has a function of removing impurities contained in the conveyed liquid developer 1 (for example, coarse toner particles, pieces of recording medium, and the like). Thereby, deterioration of the liquid developer can be prevented, and the image quality of the formed toner image can be made particularly excellent.

The liquid developer storage part P1 is provided with a circulation part P7 for circulating the liquid developer 1 in the liquid developer storage part P1.
The circulation part P7 joins with the recovered liquid developer transport part P6 at the joining part P71, and the liquid developer 1 transported through the circulation part P7 is liquid developer 1 by the filtration filter (impurity removing means) P61. Impurities accumulated therein (for example, coarse toner particles and pieces of recording media) can be removed.
The insulating liquid replenishing part P8 has a replenishing insulating liquid storage part P81 and a supply part P82 for storing the replenishing insulating liquid 10, and the replenishing insulating liquid 10 stored in the replenishing insulating liquid storage part P81. Is supplied to the liquid developer 1 in the liquid developer storage part P1 through the supply part P82.

  In the present invention, the insulating liquid contained in the liquid developer 1 is transferred to the recording medium 2 together with the toner particles in the transfer portion P3. For this reason, the insulating liquid and the toner particles in the liquid developer 1 in the liquid developer reservoir P1 are consumed by performing image formation. At this time, the insulating liquid in the liquid developer 1 in the liquid developer reservoir P1 and the toner particles may differ in consumption due to image formation, and the concentration of the toner particles in the liquid developer 1 may be different. May change. In this case, the concentration of the toner particles in the liquid developer 1 can be maintained within a predetermined range by replenishing the replenishing insulating liquid 10 with the insulating liquid replenishing portion P8. Further, by replenishing the fresh replenishing insulating liquid 10, it is possible to prevent the insulating liquid in the liquid developer 1 from deteriorating for a longer period.

The replenishing insulating liquid 10 contains a fatty acid triglyceride and a fatty acid monoester, and usually has the same composition as the insulating liquid contained in the liquid developer 1. Thereby, aggregation of the toner particles in the liquid developer reservoir P1 can be prevented more effectively, and the quality of the liquid developer can be kept high for a long time.
Further, the replenishing insulating liquid 10 may have a composition different from that of the insulating liquid contained in the liquid developer.

  Further, the replenishing insulating liquid 10 may contain toner particles. Thereby, it becomes easier to keep the toner particles in the liquid developer 1 within a predetermined range by replenishing the liquid developer 1 with the replenishing insulating liquid 10 containing the toner particles. Further, the concentration of the toner particles in the replenishing insulating liquid 10 may be higher, lower, or the same as the concentration of the toner particles contained in the liquid developer 1. Good.

Moreover, although not shown in figure, you may have the some reserve storage tank which stores the component of the replenishment insulating liquid 10 in the replenishment insulating liquid storage part P81. The constituent components in each preliminary storage tank may be the same composition as the constituent components of other preliminary storage tanks, or may be different components. In the case of different components, the replenishing insulating liquid 10 having an arbitrary composition can be easily manufactured by mixing the constituent components of the plurality of preliminary storage tanks in the replenishing insulating liquid storage part P81.
In FIG. 1, image formation using a single color liquid developer has been described. However, when an image is formed using a plurality of color toners, an image of each color is formed by using a plurality of color developing devices. An image can be formed.

FIG. 4 is a diagram illustrating an example of the fixing device.
The fixing device (fixing unit) F40 fixes the unfixed toner image 2a formed in the developing unit P2, the transfer unit P3, and the like on the recording medium 2.
As shown in FIG. 4, 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 ultraviolet irradiation means 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.
Further, the pressure roller F2 has 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.

  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 pressure roller F2 is disposed so as to face the heat fixing roller F1, and is configured to apply pressure to a recording medium F5 on which an unfixed toner image is formed via a heat-resistant belt F3 described later. ing. By applying pressure, the insulating liquid as described above can be more efficiently permeated into the recording medium F5. As a result, the unsaturated fatty acid component contained in the insulating liquid can be more reliably cured inside the recording medium F5 by heat, ultraviolet irradiation, which will be described later, and the toner image F5a is more formed on the recording medium F5 by the anchor effect. It can be firmly fixed.
Further, the pressure roller F2 has 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 or the recording medium F5 described later with respect to the peripheral speed of the heat fixing roller F1, extremely stable image fixing can be performed.
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 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 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 inserted 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 (the heat-resistant belt F3 is a belt). Sliding on the tension member F4). The 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 F5 on which the unfixed toner image F5a is formed enters the fixing nip portion from the nip initial position and passes between the heat-resistant belt F3 and the heat fixing roller F1, and the nip end position. As a result, the unfixed toner image F5a formed on the recording medium F5 is thermally fixed, and then discharged in the tangential direction L of the pressing portion of the pressure roller F2 to the heat fixing roller F1.

  The ultraviolet irradiation means F8 has a function of irradiating the surface of the recording medium F5 ejected as described above on which the toner image F5a is formed with ultraviolet rays. By adopting such a configuration, the unsaturated fatty acid component contained in the insulating liquid can be solidified more strongly by heat and ultraviolet irradiation, and as a result, the toner particles are more firmly fixed on the recording medium. Can be made. Further, since the toner particles can be firmly fixed on the recording medium without being heated to a particularly high temperature by the heat fixing roller F1 due to the irradiation of ultraviolet rays, the effect of using the liquid developer of the present invention can be obtained. Due to this synergistic effect, the toner particles can be fixed to the recording medium at a lower temperature and at a higher speed, and the toner particles can be more firmly fixed to the recording medium. Furthermore, since a large amount of heat is not required for fixing, the toner particles can be sufficiently fixed on the recording medium by irradiation with ultraviolet rays 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. As a result, an environmentally friendly fixing device can be provided.

The cleaning member F6 is disposed between the pressure roller F2 and the belt stretching member F4.
The cleaning member F6 is in slidable contact with the inner peripheral surface of the heat-resistant belt F3 and cleans foreign matter, wear powder, and the like on the inner peripheral surface of the heat-resistant belt F3. In this way, by cleaning the foreign matter, wear powder, and the like, the heat-resistant belt F3 is refreshed, and the above-described instability factor 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, or the like removed from the heat-resistant belt F3.

  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 when the time required for the toner particles to pass through the fixing nip portion is such a short time, the liquid developer of the present invention as described above can be sufficiently fixed, and the printing speed can be reduced. Further speedup can be achieved.
Specifically, the heat (fixing temperature) applied by the heat fixing roller F1 is preferably 80 to 200 ° C, and more preferably 100 to 180 ° C. When such a fixing temperature is a value within the above range, the oxidative polymerization reaction (curing reaction) of the unsaturated fatty acid component contained in the insulating liquid can be more effectively advanced.

<Second Embodiment>
Next, a second embodiment of the image forming apparatus to which the liquid developer of the present invention is applied will be described.
Note that the image forming apparatus of the present embodiment forms a color image on a recording medium using the liquid developer of the present invention as described above.

  FIG. 5 is a schematic diagram showing an example of a second embodiment of an image forming apparatus to which the liquid developer of the present invention is applied. FIG. 6 is an enlarged view of a part of the image forming apparatus shown in FIG. 7 is a conceptual perspective view showing an application roller provided in the image forming apparatus shown in FIG. 5, FIG. 8 is an enlarged schematic view of the application roller shown in FIG. 7, and FIG. 9 is a toner in a liquid developer layer on the development roller. It is a schematic diagram which shows the state of particle | grains.

As shown in FIG. 5, the image forming apparatus 1000 includes four developing units 30Y, 30M, 30C, and 30K, an intermediate transfer unit 40, a secondary transfer unit (secondary transfer unit) 60, and a first image forming apparatus. And a fixing unit (fixing device) F40 used in the embodiment.
The developing units 30Y, 30M, and 30C develop a latent image with a yellow liquid developer (Y), a magenta liquid developer (M), and a cyan liquid developer (C), respectively, and correspond to each color. It has a function of forming a single color image. The developing unit 30K has a function of developing a latent image with a black liquid developer (K) to form a black monochrome image.

Since the developing units 30Y, 30M, 30C, and 30K have the same configuration, the developing unit 30Y will be described below.
As shown in FIG. 6, the developing unit 30Y includes a photoconductor 10Y as an example of an image carrier, a charging roller 11Y, an exposure unit 12Y, a development unit 100Y, and a photoconductor along the rotation direction of the photoconductor 10Y. The image forming apparatus includes a body squeeze device 101Y, a primary transfer backup roller 51Y, a charge removal unit 16Y, a photoreceptor cleaning blade 17Y, and a developer recovery unit 18Y.

The photoreceptor 10Y has a cylindrical base material and a photosensitive layer formed on the outer peripheral surface thereof, and is rotatable about a central axis. In this embodiment, as shown by an arrow in FIG. Rotate clockwise.
Further, in such a photoreceptor 10Y, it is preferable that the photosensitive layer is made of a material such as amorphous silicon. Amorphous silicon has a very high hardness compared to a conventional organic photoconductor (OPC) and is excellent in friction resistance. Therefore, it is possible to suitably prevent the surface of the photoreceptor P21 from being damaged by the contact between the surface of the photoreceptor P21 and the toner particles. Furthermore, the deterioration of the member due to the insulating liquid in the liquid developer can be minimized. The photoreceptor P21 having such characteristics has a long life and is suitable for long-term use. In addition, it is excellent in repeated stability of electrical characteristics and environmental resistance (temperature and humidity in use environment), and can be maintained for a long time with high development accuracy on a recording medium.
The photoreceptor 10Y is supplied with a liquid developer by a developing unit 100Y described later, and a layer of the liquid developer is formed on the surface.

The charging roller 11Y is a device for charging the photoconductor 10Y, and the exposure unit 12Y is a device for forming a latent image on the photoconductor 10Y charged by irradiating a laser. The exposure unit 12Y includes a semiconductor laser, a polygon mirror, an F-θ lens, and the like, and charges a modulated laser based on an image signal input from a host computer (not shown) such as a personal computer or a word processor. Irradiate onto the photoconductor 10Y.
The developing unit 100Y is a device for developing the latent image formed on the photoreceptor 10Y using the liquid developer of the present invention. Details of the developing unit 100Y will be described later.

  The photoconductor squeeze device 101Y is disposed on the downstream side of the developing unit 100Y in the rotation direction so as to face the photoconductor 10Y. The photoconductor squeeze roller 13Y and the photoconductor squeeze roller 13Y are pressed and slidably attached to the surface. The cleaning blade 14Y removes the liquid developer and the developer collection unit 15Y that collects the removed liquid developer. The photoreceptor squeeze device 101Y has a function of collecting excess carrier (insulating liquid) and originally unnecessary fog toner from the developer developed on the photoreceptor 10Y, and increasing the ratio of toner particles in the visible image.

The primary transfer backup roller 51Y is a device for transferring a single color image formed on the photoreceptor 10Y to an intermediate transfer unit 40 described later.
The neutralization unit 16Y is a device that removes residual charges on the photoreceptor 10Y after the intermediate transfer image is transferred onto the intermediate transfer unit 40 by the primary transfer backup roller 51Y.
The photoconductor cleaning blade 17Y is a rubber member that is in contact with the surface of the photoconductor 10Y and remains on the photoconductor 10Y after the image is transferred onto the intermediate transfer portion 40 by the primary transfer backup roller 51Y. It has a function of scraping off and removing the liquid developer.
The developer recovery unit 18Y has a function of recovering the liquid developer removed by the photoconductor cleaning blade 17Y.

The intermediate transfer unit 40 is an endless elastic belt member, is wound around a belt driving roller 41 and a tension roller 42, and is stretched by the primary transfer backup rollers 51Y, 51M, 51C, and 51K. The belt drive roller 41 is rotationally driven while abutting 10M, 10C, and 10K.
A single color image corresponding to each color formed by the developing units 30Y, 30M, 30C, and 30K is sequentially transferred to the intermediate transfer unit 40 by the primary transfer backup rollers 51Y, 51M, 51C, and 51K, and a single color corresponding to each color is transferred. The images are superimposed. As a result, a full-color developer image (intermediate transfer image) is formed on the intermediate transfer portion 40.

  In the intermediate transfer unit 40, the single-color images formed on the plurality of photoconductors 10Y, 10M, 10C, and 10K are secondarily transferred and superposed one after another, and recorded on paper, film, cloth, and the like in a lump. Secondary transfer is performed on the medium F5. Therefore, when the toner image is transferred to the recording medium F5 in the secondary transfer process, even if the surface of the recording medium F5 is a sheet material that is not smooth due to fiber or the like, the secondary transfer characteristics follow the surface of the non-smooth sheet material. An elastic belt member is employed as means for improving the above.

On the side of the tension roller 42 that stretches the intermediate transfer unit 40 together with the belt driving roller 41, a cleaning device including a cleaning blade 46 and a developer recovery unit 47 is disposed.
The cleaning blade 46 has a function of scraping and removing the liquid developer adhering to the intermediate transfer portion 40 after the image is transferred onto the recording medium F5 by the secondary transfer roller 61.

The developer recovery unit 47 has a function of recovering the liquid developer removed by the cleaning blade 46.
An intermediate transfer unit squeeze device 52Y is disposed downstream of the primary transfer backup roller 51Y in the moving direction of the intermediate transfer unit 40.
The intermediate transfer unit squeeze device 52Y is provided as a means for removing excess insulating liquid from the transferred liquid developer when the liquid developer transferred onto the intermediate transfer unit 40 has not reached the desired dispersion state. ing.

The intermediate transfer unit squeeze device 52Y is in slidable contact with the intermediate transfer unit squeeze roller 53Y, the backup roller 54Y disposed opposite to the intermediate transfer unit squeeze roller 53Y across the intermediate transfer unit 40, and the intermediate transfer unit squeeze roller 53Y. It comprises a cleaning blade 55Y for cleaning the surface and a developer recovery unit 15M.
The intermediate transfer unit squeeze device 52Y has a function of recovering excess carrier from the developer primarily transferred to the intermediate transfer unit 40, increasing the toner particle ratio in the visible image, and recovering originally unwanted toner. . The developer recovery unit 15M provides a carrier recovery mechanism that is recovered by the cleaning blade 14M of the magenta photosensitive member squeeze roller disposed downstream in the moving direction of the intermediate transfer unit 40 to the cleaning blade 55Y of the intermediate transfer unit squeeze roller 53Y. Is also used. In this way, in the developer recovery unit 15 (M, C, K) of the image carrier squeeze device for the second and subsequent colors, the intermediate transfer unit 40 from the primary transfer backup roller 51 (Y, M, C) of the previous color. The intermediate transfer unit squeeze device 52 (Y, M, C) disposed downstream in the movement direction can also be used as a developer recovery unit, so that the interval between them can be regulated constant, and the structure can be simplified. Miniaturization can be achieved.

The secondary transfer unit 60 includes a cleaning device including a secondary transfer roller 61 facing the belt driving roller 41 with the intermediate transfer unit 40 interposed therebetween, and a cleaning device including a cleaning blade 62 and a developer recovery unit 63 of the secondary transfer roller 61. Be placed.
In the secondary transfer unit 60, the recording medium F5 is conveyed and supplied in accordance with the timing at which the intermediate transfer image formed on the intermediate transfer unit 40 by overlapping colors reaches the transfer position of the secondary transfer unit 60. The intermediate transfer image is secondarily transferred to the recording medium F5.
The toner image (transfer image) F5a transferred onto the recording medium F5 by the secondary transfer unit 60 is sent to a fixing unit F40, which will be described later, and is fixed.

The cleaning blade 62 has a function of scraping and removing the liquid developer adhering to the secondary transfer roller 61 after the image is transferred onto the recording medium F5 by the secondary transfer roller 61.
The developer recovery unit 63 has a function of recovering the liquid developer removed by the cleaning blade 62.

Next, the developing units 100Y, 100M, 100C, and 100K will be described in detail. In the following description, the developing unit 100Y will be typically described.
As shown in FIG. 6, the developing unit 100Y includes a liquid developer storage unit 31Y, a coating roller 32Y, a regulating blade 33Y, a developer stirring roller 34Y, a developing roller 20Y, a developing roller cleaning blade 21Y, and a developing unit. Agent compression roller (compression means) 22Y.
The liquid developer storage unit 31Y has a function of storing a liquid developer for developing the latent image formed on the photoreceptor 10Y.

The coating roller 32Y has a function of supplying a liquid developer to the developing roller 20Y.
As shown in FIG. 7, the application roller 32Y is a so-called anilox roller in which a groove 32Ya is formed in a uniform and spiral shape on the surface of a metallic roller such as iron and is plated with nickel. The diameter is about 25 mm. In the present embodiment, as shown in FIG. 7, a plurality of grooves 32Ya are formed obliquely with respect to the rotation direction D2 of the application roller 32Y by so-called cutting or rolling.
The application roller 32Y contacts the liquid developer while rotating clockwise, thereby supporting the liquid developer in the liquid developer storage unit 31Y in the groove 32Ya and supplying the supported liquid developer to the developing roller. Transport to 20Y. Accordingly, the application roller 32Y can apply the liquid developer to the developing roller 20Y with a width in the X direction in which the groove 32Ya is formed.

Note that the groove pitch (in the X direction in FIG. 8, the period between the crests forming the groove 32 Ya) is preferably about 55 to 250 μm depending on the required film thickness of the liquid developer. In this embodiment, the groove pitch P is about 80 μm, the crest width is about 40 μm, the top width PI1 of the groove 32Ya is about 50 μm, the bottom surface width PI2 is about 30 μm, the depth He of the groove 32Ya is about 20 μm, and the crest. The height Hc of 32Yb is configured to be about 30 μm, and an inclined portion SL that is monotonously formed from the center of the peak 32Yb to the bottom of the groove 32Ya is formed. In the present embodiment, the surface roughness Rz of the peak 32Yb is R1a≈1.0 μm, and the surface roughness Rz of the groove 32Ya is R2a≈1.0 μm.
When an image is formed by applying a conventional liquid developer to an image forming apparatus having a coating roller having a groove as described above, there is a problem that the above-described image unevenness appears remarkably in the formed image. However, application of the liquid developer of the present invention as described above can effectively prevent or suppress the occurrence of image unevenness.

  The regulating blade 33Y is in contact with the surface of the coating roller 32Y and regulates the amount of the liquid developer D on the coating roller 32Y. That is, the regulation blade 33Y plays a role of scraping off excess liquid developer on the application roller 32Y and measuring the liquid developer D on the application roller 32Y supplied to the development roller 20Y. The restriction blade 33Y is made of urethane rubber as an elastic body, and is supported by a restriction blade support member made of metal such as iron. Further, the regulating blade 33Y is provided on the side where the coating roller 32Y rotates and advances from the liquid developer D as viewed from the vertical surface A (that is, the left side in FIG. 6 as viewed from the vertical surface A). . The rubber hardness of the regulation blade 33Y is about 77 degrees according to JIS-A, and the hardness (about 77 degrees) of the contact portion of the regulation blade 33Y with the surface of the coating roller 32Y is about the elasticity of the developing roller 20Y described later. It is lower than the hardness (about 85 degrees) of the pressure contact portion of the body layer to the surface of the application roller 32Y.

The developer stirring roller 34Y has a function of stirring the liquid developer in a uniformly dispersed state.
In the liquid developer storage unit 31Y, the toner particles in the liquid developer have a positive charge, and the liquid developer is agitated by the developer agitation roller 34Y to be in a uniformly dispersed state. By rotating, it is pumped up from the liquid developer reservoir 31Y, the amount of liquid developer is regulated by the regulating blade 33Y, and supplied to the developing roller 20Y.

The developing roller 20Y carries the liquid developer and conveys it to the developing position facing the photoconductor 10Y in order to develop the latent image carried on the photoconductor 10Y with the liquid developer.
The developing roller 20Y forms a liquid developer layer 201Y on the surface thereof by supplying the liquid developer from the coating roller 32Y described above.
The developing roller 20Y includes a conductive elastic layer on the outer peripheral portion of an inner core made of metal such as iron, and has a diameter of about 20 mm. The elastic layer has a two-layer structure. As an inner layer, urethane rubber having a rubber hardness of about 30 degrees and a thickness of about 5 mm is used. As a surface layer (outer layer), the rubber hardness is JIS. -A urethane rubber having a thickness of about 30 μm at about 85 degrees A is provided. The developing roller 20Y is in pressure contact with the application roller 32Y and the photoreceptor 10Y in a state of elastic deformation with the surface layer serving as a pressure contact portion.

  Further, the developing roller 20Y can rotate around its central axis, and the central axis is below the rotational central axis of the photoconductor 10Y. Further, the developing roller 20Y rotates in a direction (counterclockwise in FIG. 6) opposite to the rotation direction of the photoreceptor 10Y (clockwise in FIG. 6). When developing the latent image formed on the photoconductor 10Y, an electric field is formed between the developing roller 20Y and the photoconductor 10Y.

  The developer compression roller 22Y is a device having a function of compressing the liquid developer toner carried on the development roller 20Y. In other words, the developer compression roller 22Y applies an electric field having the same polarity as that of the toner particles 1 to the liquid developer layer 201Y described above, thereby developing the liquid developer layer 201Y in the liquid developer layer 201Y as shown in FIG. This is a device having a function of unevenly distributing the toner particles 1 near the surface of the roller 20Y. By unevenly distributing the toner particles in this way, the development density (development efficiency) can be improved, and as a result, a clear image with high quality can be obtained.

The developer compression roller 22Y is provided with a cleaning blade 23Y.
The cleaning blade 23Y has a function of removing the liquid developer adhering to the developer compression roller 22Y.
Further, the developing unit 100Y includes a rubber developing roller cleaning blade 21Y that is in contact with the surface of the developing roller 20Y. The developing roller cleaning blade 21Y is a device for scraping off and removing the liquid developer remaining on the developing roller 20Y after development is performed at the developing position. The liquid developer removed by the developing roller cleaning blade 21Y is collected in the liquid developer storage unit 31Y and reused.

In addition, the image forming apparatus 1000 includes a reuse device that reuses the insulating liquid in the liquid developer collected in each developer collection unit (15, 18, 47, 63).
The recycling apparatus includes a transport path 70 that transports the recovered liquid developer from each developer recovery unit, a filter unit 77 that removes the solid content (toner particles and the like) of the transported liquid developer, And an insulating liquid storage part 74 for storing the insulating liquid from which the solid content has been removed by the filter means 77.

A pump 76 is provided in the conveyance path 70, and the liquid developer collected in each developer collection unit is conveyed to the insulating liquid storage unit 74 by the pump 76.
The insulating liquid stored in the insulating liquid storage unit 74 is appropriately transported to each developing unit and reused by a transport unit (not shown).
The solid content removed by the filter unit 77 is detected by a filter state detection unit (not shown). Then, the filter means 77 is replaced based on the detection result. Thereby, the filtering function of the filter means 77 can be maintained stably.

As mentioned above, although this invention was demonstrated based on suitable embodiment, this invention is not limited to these.
The insulating liquid of the present invention may contain components other than the above-described fatty acid triglycerides and fatty acid monoesters. Examples of such a component may include a diester (diglyceride) of a diol represented by ethylene glycol, propylene glycol and the like and a fatty acid. Further, it may contain a diester (diglyceride) composed of one molecule of glycerin and two molecules of fatty acid, or a monoester (monoglyceride) composed of one molecule of fatty acid in one molecule of glycerin. Even if the insulating liquid contains these components, it is possible to provide a liquid developer that sufficiently satisfies the above-described effects.

Further, for example, the liquid developer of the present invention is not limited to those applied to the image forming apparatus and the fixing apparatus as described above.
Further, the liquid developer of the present invention is not limited to those produced by the production method as described above.
In the above-described embodiment, it has been described that an aqueous dispersion is obtained and an association particle is obtained by adding an electrolyte to the aqueous emulsion. However, the present invention is not limited to this. For example, the associating particles are prepared by dispersing a colorant, a monomer, a surfactant, and a polymerization initiator in an aqueous liquid, preparing an aqueous dispersion by emulsion polymerization, and adding an electrolyte to the aqueous dispersion to be associated. It may be prepared using an emulsion polymerization association method, or may be obtained by spray-drying the obtained aqueous dispersion to obtain associated particles.

[1] Production of liquid developer (Example 1)
First, polyester resin (softening temperature: 99 ° C., acid value: 7.0 mg KOH / g): 80 parts by weight, 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.
The kneaded product cooled as described above was coarsely pulverized to obtain a powder (coarse pulverized 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 and a soybean oil transesterification solution produced by a transesterification reaction between soybean oil and methanol (manufactured by Nisshin Oilio Co., Ltd., trade name “soybean oil”) Fatty acid methyl ”, acid value 0.1 mg KOH / g): 160 parts by weight, polyamine fatty acid polycondensation polymer as a dispersant (trade name“ Solsperse 13940 ”manufactured by Nippon Lubrizol Co., Ltd.): 2.5 parts by weight, water Phenol phosphite compound a (tetratridecyl-4,4′-butylidenebis (2-tert-butyl-5-methylphenyl) diphosphite) as a decomposition inhibitor: 2.0 parts by weight was prepared. In addition, content of the fatty acid monoester in soybean oil transesterification liquid was 99.9 wt% or more.
These components were put into a ball mill and wet pulverized for 200 hours to obtain a pulverized dispersion.
Thereafter, 264.5 parts by weight of the obtained pulverized dispersion liquid and 240 parts by weight of soybean oil (Nisshin Oilio Co., Ltd.) were mixed to obtain a liquid developer. In addition, content of the fatty acid triglyceride contained in soybean oil was 99.9 wt% or more.

The average particle diameter of the toner particles in the obtained liquid developer was 1.5 μm, and the standard deviation of the particle diameter between the toner particles was 0.65 μm. Further, the viscosity of the liquid developer measured in accordance with JIS Z8809 using a vibration viscometer at 25 ° C. was 233 mPa · s. Further, an acid obtained by separately measuring a liquid obtained by separately mixing soybean oil transesterification liquid, soybean oil, and phenol phosphite compound a in a liquid developer at a blending ratio contained in the liquid developer in accordance with JIS K2501. The value of the value was 0.07 mg KOH / g. Further, the electric resistance of the liquid developer was 2.1 × 10 ¹² Ωcm. The average particle size of each toner particle in each example and comparative example is a volume-based average particle size, and the average particle size and particle size distribution of these particles are determined by a Mastersizer 2000 particle analyzer (manufactured by Malvern Instruments Ltd.). Measurements were made at

(Examples 2 to 4)
A liquid developer was produced in the same manner as in Example 1 except that the contents of the soybean oil transesterification solution and soybean oil were adjusted to the values shown in Table 1.
(Example 5)
Instead of soybean oil fatty acid methyl, rapeseed oil transesterification liquid produced by transesterification of rapeseed oil and ethanol (Nisshin Oilio Co., Ltd., trade name “rapeseed oil fatty acid ethyl”, acid value 0.08 mg KOH / g) was used. A liquid developer was produced in the same manner as in Example 1 except for the above.

(Example 6)
A soybean oil transesterification solution (acid value 0.07 mgKOH / g) produced by a transesterification reaction between soybean oil and n-propanol was used in the same manner as in Example 1 except that the soybean oil fatty acid methyl was used. Thus, a liquid developer was produced.
(Example 7)
A liquid developer was produced in the same manner as in Example 1, except that HO rapeseed oil (manufactured by Nisshin Oillio Co., Ltd.) was used instead of soybean oil.

(Example 8)
Example 1 except that soybean oil and soybean oil fatty acid methyl were changed to safflower oil (manufactured by Nissin Oilio Co., Ltd.) and soybean oil transesterification solution produced by transesterification of soybean oil and heptanol, respectively. A liquid developer was produced in the same manner as described above.
Example 9
The same as in Example 1 except that phenol phosphite compound b (tris (2,4-di-tert-butylphenyl) phosphite) was used in place of phenol phosphite compound a as the hydrolysis inhibitor. Thus, a liquid developer was produced.

(Example 10)
A liquid developer was produced in the same manner as in Example 7 except that the amount of the phenol phosphite compound a introduced into the ball mill was changed to 0.1 parts by weight.
(Example 11)
A liquid developer was produced in the same manner as in Example 1 except that the amount of the phenol phosphite compound a introduced into the ball mill was changed to 22.0 parts by weight.

(Example 12)
As a hydrolysis inhibitor, a phenol phosphite compound c (triphenyl phosphite) was used instead of the phenol phosphite compound a, and the amount charged into the ball mill was changed to 7.0 parts by weight. A liquid developer was produced in the same manner as in Example 1.
(Example 13)
As the hydrolysis inhibitor, instead of phenol phosphite compound a, phenol phosphite compound d (diphenyl phosphite) was used, except that the amount charged to the ball mill was changed to 10.0 parts by weight. A liquid developer was produced in the same manner as in Example 1.
(Example 14)
A liquid developer was produced in the same manner as in Example 1 except that the polyester resin was changed to an epoxy resin (Epicoat 1004, softening temperature: 128 ° C.).

(Example 15)
First, 80 parts by weight of a polyester resin (softening temperature: 99 ° C.) and 20 parts by weight of a cyan pigment as a coloring agent (Pigment Blue 15: 3, manufactured by Dainichi Seika Co., Ltd.) 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 (coarse pulverized 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 of the kneaded product was added to 250 parts by weight of toluene, and the polyester resin of the kneaded product was dissolved by treating with an ultrasonic homogenizer (output: 400 μA) for 1 hour. A solution (toner material solution) was obtained. In this solution, the pigment was uniformly finely dispersed.
On the other hand, an aqueous liquid in which sodium dodecylbenzenesulfonate as a dispersant: 1 part by weight and ion-exchanged water: 700 parts by weight were uniformly mixed was prepared.
The aqueous liquid was stirred with a homomixer (made by Tokushu Kika Kogyo Co., Ltd.) while adjusting the stirring rotation speed.
The toner material solution was dropped into the agitated aqueous liquid. As a result, an aqueous emulsion in which the dispersoid having an average particle size of 0.5 μm was uniformly dispersed was obtained.

  Thereafter, the toluene in the aqueous emulsion is removed under the conditions of temperature: 100 ° C. and atmospheric pressure: 80 kPa, and after cooling to room temperature, the concentration of the solid fine particles is adjusted by adding a predetermined amount of water. A dispersed aqueous dispersion was obtained. In the resulting aqueous dispersion, substantially no toluene remained. The obtained aqueous dispersion had a solid content (dispersoid) concentration of 20 wt%. The average particle size of the dispersoid (solid fine particles) dispersed in the suspension was 0.5 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.).

Next, 0.35 part by weight of a nonionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., trade name “Epan 450”) is added to 100 parts by weight of the obtained aqueous dispersion while stirring. did.
Next, while adjusting the stirring speed and setting the temperature to 30 ° C., 35 parts by weight of 3% aqueous ammonium sulfate solution was added dropwise to 100 parts by weight of the aqueous dispersion. As a result, an associated particle dispersion in which associated particles are dispersed was obtained.
From the obtained associated particle dispersion, the associated particles were separated by a centrifugal separator, washed, and then dried by a vacuum dryer to obtain associated particles. The average particle diameter of the obtained associated particles was 5.2 μm.

  Next, 4 mm carbon chrome beads are put into a 500 mL container, and then a soybean oil transesterification solution produced by a transesterification reaction between soybean oil and methanol (manufactured by Nisshin Oilio Co., Ltd., trade name “methyl soybean oil fatty acid”). ”, Acid value 0.1 mg KOH / g): 150 parts by weight, and polyamine fatty acid condensation polymer (trade name“ Solsperse 13940 ”, manufactured by Nippon Lubrizol Co., Ltd.) as a dispersant: 2.5 parts by weight.

Next, 100 parts by weight of the obtained associated particles were added, mixed for 10 minutes with a ball mill, and then crushed with a ball mill for 200 hours to obtain a toner dispersion.
After pulverization, HO rapeseed oil: 225 parts by weight, zinc oxide as a charge control agent (average particle size: 1.0 μm): 1.4 parts by weight, and phenol phosphite compound a as a hydrolysis inhibitor: 2.0 parts by weight were charged to disperse the toner particles. Dispersion was carried out for 24 hours by adding 1 mm beads using a ball mill. As a result, a liquid developer was obtained.
The average particle size of the toner particles in the obtained liquid developer was 1.2 μm, and the standard deviation of the particle size between the toner particles was 0.50 μm. Moreover, the viscosity of the liquid developer measured according to JIS Z8809 using a vibration viscometer at 25 ° C. was 219 mPa · s. Further, the electric resistance of the liquid developer was 2.1 × 10 ¹² Ωcm.

(Example 16)
A liquid developer was produced in the same manner as in Example 15 except that a safflower oil transesterification solution produced by transesterification of safflower oil and methanol was used instead of soybean oil fatty acid methyl.
(Example 17)
First, soybean oil transesterification liquid used in Example 15: 150 parts by weight, HO rapeseed oil: 225 parts by weight, polyamine fatty acid stagnation polymer: 2.5 parts by weight, and phenol phosphite compound a: 2.0 Part by weight and 1.4 parts by weight of zinc oxide were mixed to obtain an insulating liquid. Next, the insulating liquid thus obtained: 380.9 parts by weight and the associated particles obtained in Example 15: 100 parts by weight were mixed with the ball mill used in Example 15 for 10 minutes, and then And pulverized with a ball mill for 400 hours to obtain a liquid developer.

(Example 18)
A liquid developer was produced in the same manner as in Example 1 except that the phenol phosphite compound a was not added to the ball mill.

(Example 19)
A liquid developer was produced in the same manner as in Example 18 except that methyl soybean oil fatty acid having an acid value of 20 mgKOH / g was used as soybean oil fatty acid methyl.
(Example 20)
A liquid developer was produced in the same manner as in Example 15 except that a soybean oil transesterification solution produced by a transesterification reaction between soybean oil and n-octyl alcohol was used in place of the soybean oil fatty acid methyl.

(Example 21)
A liquid developer was produced in the same manner as in Example 1 except that a soybean oil transesterification solution produced by a transesterification reaction between soybean oil and n-octyl alcohol was used in place of the soybean oil fatty acid methyl.
(Example 22)
A liquid developer was produced in the same manner as in Example 7 except that the phenol phosphite compound a was not added to the ball mill.
(Example 23)
Example 22 except that ethyl linoleate (acid value 0.2 mg KOH / g) produced by transesterification of linoleic acid and primary alcohol ethanol was used instead of soybean oil fatty acid methyl. A liquid developer was produced in the same manner.

(Example 24)
First, polyester resin (softening temperature: 99 ° C., acid value: 7.0 mg KOH / g): 80 parts by weight, 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.
The kneaded material cooled as described above was coarsely pulverized to obtain a powder having an average particle size of 1.0 mm or less (coarse pulverized product). 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, and a soybean oil transesterification solution produced by a transesterification reaction between soybean oil and isopropanol, which is a secondary alcohol (soybean oil fatty acid isopropyl, An acid value of 0.1 mg KOH / g): 160 parts by weight and a polyamine fatty acid polycondensation polymer (trade name “Solsperse 13940” manufactured by Nippon Lubrizol Co., Ltd.) as a dispersing agent: 2.5 parts by weight were prepared. The content of fatty acid monoester in the transesterification liquid was 99.9 wt% or more.
These components were put into a ball mill and wet pulverized for 200 hours to obtain a pulverized dispersion.
Thereafter, the obtained pulverized dispersion liquid: 264.5 parts by weight and HO rapeseed oil (Nisshin Oilio Co., Ltd.): 240 parts by weight were mixed to obtain a liquid developer. In addition, content of the fatty acid triglyceride contained in soybean oil was 99.9 wt% or more.
The average particle size of the toner particles in the obtained liquid developer was 1.5 μm, and the standard deviation of the particle size between the toner particles was 0.65 μm. The viscosity of the liquid developer measured in accordance with JIS Z8809 using a vibration viscometer at 25 ° C. was 312 mPa · s. Moreover, the value of the acid value measured in accordance with JIS K2501 for a liquid obtained by separately mixing soybean oil transesterification liquid in liquid developer and HO rapeseed oil at a blending ratio contained in the liquid developer is 0. 1 mg KOH / g. The electric resistance of the liquid developer was 3.1 × 10 ¹² Ωcm.
(Examples 25-32)
A liquid developer was produced in the same manner as in Example 24 except that at least one of the fatty acid monoester, the amount of fatty acid triglyceride used, and the raw material used in the production thereof was changed.

(Example 33)
First, 80 parts by weight of a polyester resin (softening temperature: 99 ° C.) and 20 parts by weight of a cyan pigment as a coloring agent (Pigment Blue 15: 3, manufactured by Dainichi Seika Co., Ltd.) 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 (coarse pulverized 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 of the kneaded product was added to 250 parts by weight of toluene, and the polyester resin of the kneaded product was dissolved by treating with an ultrasonic homogenizer (output: 400 μA) for 1 hour. A solution (toner material solution) was obtained. In this solution, the pigment was uniformly finely dispersed.
On the other hand, an aqueous liquid in which sodium dodecylbenzenesulfonate as a dispersant: 1 part by weight and ion-exchanged water: 700 parts by weight were uniformly mixed was prepared.
The aqueous liquid was stirred with a homomixer (made by Tokushu Kika Kogyo Co., Ltd.) while adjusting the stirring rotation speed.
The toner material solution was dropped into the agitated aqueous liquid. As a result, an aqueous emulsion in which the dispersoid having an average particle size of 0.5 μm was uniformly dispersed was obtained.

  Thereafter, the toluene in the aqueous emulsion is removed under the conditions of temperature: 100 ° C. and atmospheric pressure: 80 kPa, and after cooling to room temperature, the concentration of the solid fine particles is adjusted by adding a predetermined amount of water. A dispersed aqueous dispersion was obtained. In the resulting aqueous dispersion, substantially no toluene remained. The obtained aqueous dispersion had a solid content (dispersoid) concentration of 20 wt%. The average particle size of the dispersoid (solid fine particles) dispersed in the suspension was 0.5 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.).

Next, 0.35 part by weight of a nonionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., trade name “Epan 450”) is added to 100 parts by weight of the obtained aqueous dispersion while stirring. did.
Next, while adjusting the stirring speed and setting the temperature to 30 ° C., 35 parts by weight of 3% aqueous ammonium sulfate solution was added dropwise to 100 parts by weight of the aqueous dispersion. As a result, an associated particle dispersion in which associated particles are dispersed was obtained.
From the obtained associated particle dispersion, the associated particles were separated by a centrifugal separator, washed, and then dried by a vacuum dryer to obtain associated particles. The average particle diameter of the obtained associated particles was 5.2 μm.

  Next, 4 mm carbon chromium beads are put into a 500 mL container, and then a soybean oil transesterification solution (soybean oil fatty acid isopropyl, acid value 0.1 mgKOH / g) produced by a transesterification reaction between soybean oil and isopropanol. : 150 parts by weight and polyamine fatty acid polycondensate as a dispersant (manufactured by Nippon Lubrizol Corporation, trade name “Solsperse 13940”): 2.5 parts by weight were charged.

Next, 100 parts by weight of the obtained associated particles were added, mixed for 10 minutes with a ball mill, and then crushed with a ball mill for 200 hours to obtain a toner dispersion.
After pulverization, 225 parts by weight of HO rapeseed oil was added to disperse the toner particles. Dispersion was carried out for 24 hours by adding 1 mm beads using a ball mill. As a result, a liquid developer was obtained.
The average particle size of the toner particles in the obtained liquid developer was 1.2 μm, and the standard deviation of the particle size between the toner particles was 0.50 μm. Moreover, the viscosity of the liquid developer measured according to JIS Z8809 using a vibration viscometer at 25 ° C. was 232 mPa · s. Further, the electric resistance of the liquid developer was 2.6 × 10 ¹² Ωcm.

(Example 34)
Instead of soybean oil fatty acid isopropyl, safflower oil transesterification liquid (safflower oil) produced by transesterification of safflower oil and tertiary alcohol 1,1-dimethyl-1-propanol (tert-pentanol). A liquid developer was produced in the same manner as in Example 33 except that flower oil fatty acid tert-pentyl, acid value 0.08 mgKOH / g) was used.

(Example 35)
First, soybean oil fatty acid isopropyl used in Example 33: 150 parts by weight, HO rapeseed oil: 225 parts by weight, polyamine fatty acid condensation polymer: 2.5 parts by weight, and zinc oxide: 1.4 parts by weight And an insulating liquid was obtained. Next, the insulating liquid thus obtained: 380.9 parts by weight and the associated particles obtained in Example 10: 100 parts by weight were mixed with the ball mill used in Example 10 for 10 minutes, and then And pulverized with a ball mill for 400 hours to obtain a liquid developer.
(Examples 36 and 37)
A liquid developer is produced in the same manner as in Example 7 except that the type and content of the fatty acid monoester contained in the insulating liquid and the content of the phenol phosphite compound a are changed as shown in Table 1. did.

(Comparative Example 1)
A liquid developer was produced in the same manner as in Example 1 except that a soybean oil transesterification solution produced by a transesterification reaction between soybean oil and n-nonyl alcohol was used in place of the soybean oil fatty acid methyl.
(Comparative Example 2)
A liquid developer was produced in the same manner as in Example 24 except that the type of fatty acid monoester used was changed as shown in Table 2.

(Comparative Example 3)
A liquid developer was produced in the same manner as in Example 30 except that the soybean oil fatty acid isopropyl was replaced with soybean oil.
(Comparative Example 4)
A liquid similar to Example 24 except that the HO rapeseed oil was replaced with a soybean oil transesterification solution (soybean oil fatty acid isopropyl, acid value 0.1 mg KOH / g) produced by a transesterification reaction between soybean oil and isopropanol. A developer was produced.

(Comparative Example 5)
A coarsely pulverized product was obtained in the same manner as in Example 1.
Next, the obtained coarsely pulverized product: 100 parts by weight, soybean oil (manufactured by Nissin Oilio Co., Ltd.): 160 parts by weight, and polyamine fatty acid condensation polymer (manufactured by Nippon Lubrizol Co., Ltd., trade name “Solsperse 13940”) ]): 2.5 parts by weight and phenol phosphite compound a: 2.0 parts by weight were prepared.
These components were put into a ball mill and wet pulverized for 400 hours to obtain a pulverized dispersion.
Thereafter, the obtained pulverized dispersion liquid: 264.5 parts by weight, soybean oil: 240 parts by weight, and zinc oxide as a charge control agent (average particle size: 1.0 μm): 1.4 parts by weight are mixed. As a result, a liquid developer was obtained.
The average particle diameter of the toner particles in the obtained liquid developer was 4.8 μm, and the standard deviation of the particle diameter between the toner particles was 2.92 μm. Moreover, the viscosity of the liquid developer measured according to JIS Z8809 using a vibration viscometer at 25 ° C. was 595 mPa · s. In addition, the electrical resistance of the insulating liquid was 1.6 × 10 ¹³ Ωcm, and the electrical resistance of the liquid developer was 4.6 × 10 ¹² Ωcm.
(Comparative Example 6)
A liquid developer was produced in the same manner as in Example 1 except that the soybean oil and soybean oil transesterification solution were all replaced with Isopar H (Exxon Chemical Co., Ltd.).

  For each of the above Examples and Comparative Examples, the type of resin used, the raw material of the fatty acid triglyceride, the content in the insulating liquid, and the type and content of the fatty acid component included, the raw material of the fatty acid monoester, the insulating liquid Tables 1 and 2 show the content, the type and content of the fatty acid component contained therein, the type of the alcohol component contained, the viscosity of the liquid developer, the electrical resistance of the liquid developer, and the like.

Moreover, in Table 1, polyester resin is PEs, epoxy resin is EP, methanol is MeOH, ethanol is EtOH, n-propanol is n-PrOH, heptanol is HepOH, n-octyl alcohol is OctOH, n-nonyl alcohol is NonOH, Isopropanol is i-PrOH, 2-butanol (sec-butanol) is 2-BuOH, 1,1-diethyl-3-methyl-1-propanol (tert-octanol) is tert-OctOH, 1,1-dimethyl-1- Propanol (tert-pentanol) is t-PeOH, methanol is MeOH, ethanol is EtOH, 7-methyl-1-octanol is 7-Me-1-OctOH, and phenol phosphite compound a is used as a hydrolysis inhibitor. a, phenolphos Aito compound b to b, and phenol phosphite compound c c, phenol phosphite compound d shown d. In
In addition, the viscosity and electrical resistance in Tables 1 and 2 were expressed according to the following four-stage criteria.

<Viscosity>
A: 150 mPa · s or more and 800 mPa · s or less.
B: 100 mPa · s or more and 900 mPa · s or less. (Except 150mPa · s to 800mPa · s)
C: 50 mPa · s or more and 1000 mPa · s or less. (Except 100mPa · s to 900mPa · s)
D: Less than 50 mPa · s or more than 1000 mPa · s.

<Electric resistivity>
A: 2.0 × 10 ¹² Ωcm or more.
B: 1.5 × 10 ¹² Ωcm or more and less than 2.0 × 10 ¹² Ωcm.
C: 1.0 × 10 ¹² Ωcm or more and less than 1.5 × 10 ¹² Ωcm.
D: Less than 1.0 × 10 ¹² Ωcm.

[2] Evaluation Each liquid developer obtained as described above was evaluated as follows.
[2.1] Fine character printing performance Using the image forming apparatus as shown in FIG. 1 and the fixing device as shown in FIG. Monochromatic two-point characters were formed on recording paper (quality paper LPCPPA4 manufactured by Seiko Epson Corporation), and heat fixing was performed.
Thereafter, the obtained toner image (two-point characters) was visually observed and evaluated according to the following five criteria.

A: 2 point characters can be seen very clearly.
B: 2 point characters can be clearly seen.
C: Two-point characters can be visually recognized with a slight blur.
D: Two-point characters can be visually recognized with blur.
E: 2 point characters cannot be visually recognized.

[2.2] Environmental stability (long-term stability)
The liquid developers obtained in the respective Examples and Comparative Examples were allowed to stand for 6 months in an environment of 35 ° C. and a relative humidity of 65%. Thereafter, the state of the liquid developer was observed, and changes in the viscosity, color, acid value, and electrical resistance value before and after being allowed to stand were evaluated according to the following five criteria. The acid value was measured according to JIS K2501. The change in color of the liquid developer was evaluated visually. The viscosity was measured according to JIS Z8809 using a vibration viscometer. In addition, the electrical resistance value was measured using a universal electrometer MMAII-17B, a liquid electrode LP-05, and a shield box P-618 (manufactured by Kawaguchi Electric Manufacturing Co., Ltd.).

A: No change in viscosity / color / acid value / electric resistance value of the liquid developer is observed.
B: Almost no change in viscosity / color / acid value / electric resistance value of the liquid developer is observed.
C: A slight change in viscosity / color / acid value / electric resistance value of the liquid developer is observed, but it is in a range where there is no problem as a liquid developer.
D: A change in viscosity / color / acid value / electric resistance value of the liquid developer is clearly recognized.
E: A change in the viscosity / color / acid value / electric resistance value of the liquid developer is noticeable.

[2.3] Preservability The liquid developers obtained in the respective Examples and Comparative Examples were allowed to stand for 6 months in an environment at a temperature of 15 to 25 ° C. Thereafter, the state of the toner in the liquid developer was visually confirmed and evaluated according to the following five-step criteria.
A: No toner particle floating or coagulation sedimentation is observed.
B: Floating and coagulation sedimentation of toner particles are hardly observed.
C: Slight floating or coagulation sedimentation of toner particles is observed, but as a liquid developer
There is no problem.
D: Floating or coagulation sedimentation of toner particles is clearly observed.
E: Suspension and coagulation sedimentation of toner particles are remarkably observed.

[2.4] Fixing Strength Using an image forming apparatus as shown in FIG. 1, an image of a predetermined pattern with a liquid developer obtained in each of the above examples and each of the comparative examples was recorded on a recording paper (manufactured by Seiko Epson Corporation). It was formed on fine paper LPCPPA4). Thereafter, heat fixing was performed using a fixing device as shown in FIG.
Thereafter, after confirming the non-offset area, the fixed image on the recording paper is erased twice (rubber eraser “LION 261-11” manufactured by Lion Business Machine Co., Ltd.) with a pressing load of 1.0 kgf, and the residual ratio of image density Was measured by “X-Rite model 404” manufactured by X-Rite Inc, and evaluated according to the following five-step criteria.

A: Image density remaining rate is 95% or more.
B: Image density remaining ratio is 90% or more and less than 95%.
C: Image density remaining rate is 80% or more and less than 90%.
D: Image density remaining ratio is 70% or more and less than 80%.
E: Image density remaining rate is less than 70%.

[2.5] Peel Strength Using an image forming apparatus as shown in FIG. 1, images of a predetermined pattern with a liquid developer obtained in each of the examples and the comparative examples were recorded on a recording paper (manufactured by Seiko Epson Corporation, It was formed on fine paper LPCPPA4). Thereafter, thermal fixing was performed using a fixing device as shown in FIG. 4 at a set temperature of the heat fixing roller of 180 ° C.
After confirming the non-offset area, a Scotch mending tape 10 mm width 810-1-18 was applied to the fixed image on the recording paper, and the tape was peeled off at a speed of 5 cm / s in a direction of 170 ° with respect to the recording paper surface. The residual ratio of image density was measured by “X-Rite model 528” manufactured by X-Rite Inc, and evaluated according to the following five-step criteria.

A: Image density remaining rate is 95% or more.
B: Image density remaining ratio is 90% or more and less than 95%.
C: Image density remaining rate is 80% or more and less than 90%.
D: Image density remaining ratio is 70% or more and less than 80%.
E: Image density remaining rate is less than 70%.

[2.6] Durability The image forming apparatus as shown in FIG. 1 and the image forming apparatus as shown in FIG. In each image forming apparatus, 8000 sheets of a predetermined pattern (5% printing) were continuously printed on a recording medium (Seiko Epson, A4 fine plain paper). The degree of image defects such as blurring was visually evaluated and evaluated according to the following five-step criteria. In the image forming apparatus as shown in FIG. 1, as the insulating liquid in the replenishing insulating liquid reservoir, the resin material and the colorant among the components constituting the liquid developer of each of the embodiments and the comparative examples are used. What mixed the component except was used.

A: Image defects such as blurring were not recognized at all in 8000 images formed.
B: Image defects such as blurring were first recognized in the image formed on the 7000th to 7999th sheets.
C: Image defects such as blurring were first recognized in the image formed on the 6000th to 6999th sheets.
D: Image defects such as blurring were first recognized in the image formed on the 4000th to 5999th sheets.
E: Image defects such as blurring were observed in the image formed on the 1st to 3999th sheets.
These results are shown together with the average particle diameter of the toner particles contained in each liquid developer obtained in each Example and each Comparative Example, and the standard deviation of the particle diameter between toner particles constituting each liquid developer. 3 and shown in Table 4.

As apparent from Tables 3 and 4, the toner particles contained in the liquid developer of each example have a sufficiently small particle size, and as a result, formed using the liquid developer of each example. The toner image had excellent resolution. On the other hand, satisfactory results could not be obtained with the liquid developers of the comparative examples. Further, when the liquid developer of each comparative example was produced, the pulverization and pulverization time of the toner material was further extended, but the pulverization did not proceed, and the obtained toner particles contained a large amount of coarse particles. It was.
Further, the liquid developers in Examples 1 to 17 and Examples 24 to 36 were excellent in environmental stability (long-term stability), storage stability, fixing characteristics, and durability.

Further, for each of the liquid developers obtained in Example 24, Example 28, Example 30, and Example 33, when evaluating the storage stability of the liquid developer of [2.3], the temperature was higher (40- Even at 45 ° C., no toner particle floating or coagulation sedimentation was observed after standing for 6 months. Furthermore, when evaluating the environmental stability in [2.2], these liquid developers were left to stand for 6 months under the same conditions and evaluated in the same manner. No change in color, acid value or electrical resistance was observed.
In addition, the liquid developer was manufactured and evaluated in the same manner as described above except that Pigment Red 122, Pigment Yellow 180, and Carbon Black (Printex L, manufactured by Degussa) were used as the colorant instead of the cyan pigment. As a result, the same result as above was obtained.

1 is a cross-sectional view illustrating an example of an image forming apparatus to which a liquid developer of the present invention is applied. FIG. 4 is a perspective view illustrating an example of a line head exposure unit of an image forming apparatus to which the liquid developer of the present invention is applied. FIG. 4 is a cross-sectional view in the sub-scanning direction of a line head exposure unit of an image forming apparatus to which the liquid developer of the present invention is applied. FIG. 3 is a cross-sectional view illustrating an example of a fixing device to which the liquid developer of the present invention is applied. It is a schematic diagram showing an example of a second embodiment of an image forming apparatus to which the liquid developer of the present invention is applied. FIG. 6 is an enlarged view of a part of the image forming apparatus shown in FIG. 5. FIG. 6 is a perspective conceptual diagram illustrating a coating roller included in the image forming apparatus illustrated in FIG. 5. It is an expansion schematic diagram of the application | coating roller shown in FIG. FIG. 6 is a schematic diagram illustrating a state of toner particles in a liquid developer layer on a developing roller.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid developer 2 ... Recording medium 2a ... Toner image 10 ... Replenishment insulating liquid P100 ... Image forming apparatus P1 ... Liquid developer storage part P2 ... Development part P21 ... Photoconductor P211 ... Charger P212 ... Line head exposure part P2120 ... Housing P2121 ... Light emitting element array P2122 ... Glass substrate P2123 ... Sealing member P2124 ... Refractive index distribution type rod lens array P2124 '... Refractive index distribution type rod lens P2125 ... Cover P2126 ... Fixed plate spring P2127 ... Thin film transistor P213 ... Static electricity removal P22 ... Liquid supply roller P23 ... Liquid thickness regulating roller P231 ... Liquid thickness regulating blade P24 ... Developing roller P3 ... Transfer part P31 ... Intermediate transfer belt P32 ... Secondary transfer roller P4 ... Developing part liquid collecting part P41 ... Developing roller upper liquid collecting part P411 ... cleaning blade P42 ... photosensitive member liquid recovery part P421 ... cleaning blade P5 ... transfer part liquid recovery part P51 ... cleaning blade P6 ... recovered liquid developer transport part P60 ... pump P61 ... filtration filter (impurity removing means) P7 ... circulation part P71 ... Junction part P8 ... Insulating liquid supply part P81 ... Replenishment insulating liquid storage part P82 ... Supply part F40 ... Fixing device F1 ... Heat fixing roller (heating roller) F1a ... Columnar halogen lamp F1b ... Roller base material F1c ... Elastic body F2 ... Pressure roller F2a ... Rotating shaft F2b ... Roller base material F2c ... Elastic body F3 ... Heat-resistant belt F4 ... Belt tension member F4a ... Protruding wall F4f ... Concavity F5 ... Recording medium F5a ... Toner image F6 ... Cleaning member F7 ... Frame F8 ... UV irradiation means F9 ... Spring 1000: Image forming apparatus 10Y, 10M, 10C, 10K ... Photoconductors 11Y, 11M, 11C, 11K ... Charging rollers 12Y, 12M, 12C, 12K ... Exposure unit 13Y ... Photoconductor squeeze rollers 14M, 14Y ... Cleaning blade 15Y ... Development Agent recovery unit 16Y: Static elimination unit 17Y ... Photoconductor cleaning blade 18Y ... Developer recovery unit 20Y, 20M, 20C, 20K ... Development roller 201Y ... Liquid developer layer 21Y ... Development roller cleaning blade 22Y ... Developer compression roller 23Y ... Development Agent compression roller cleaning blades 30Y, 30M, 30C, 30K ... developing unit 31Y ... liquid developer storage unit 32Y ... application roller 33Y ... regulating blade 34Y ... stirring roller 40 ... intermediate transfer unit 41 ... belt drive roller 42 Tension roller 46 ... Intermediate transfer part cleaning blade 47 ... Developer recovery part 51Y, 51M, 51C, 51K ... Primary transfer backup roller 52Y, 52M, 52C, 52K ... Intermediate transfer part squeeze device 53Y ... Intermediate transfer part squeeze roller 54Y ... Intermediate transfer unit squeeze backup roller 55Y ... Intermediate transfer unit squeeze roller cleaning blade 56Y ... Developer recovery unit 60 ... Secondary transfer unit 61 ... Secondary transfer roller 62 ... Secondary transfer roller cleaning blade 63 ... Developer recovery unit 70 ... Conveyance Path 74: Insulating liquid reservoir 76 ... Pump 77 ... Filter means 100Y ... Development unit 101Y ... Photoconductor squeeze device

Claims (14)

An insulating liquid used in a liquid developer containing toner particles,
Containing fatty acid triglycerides and fatty acid monoesters,
The fatty acid triglyceride and the fatty acid monoester contain an unsaturated fatty acid as a fatty acid component,
An insulating liquid, wherein the alcohol component constituting the fatty acid monoester has an alkyl group having 1 to 8 carbon atoms.   The insulating liquid according to claim 1, wherein the alcohol component has a linear alkyl group having 1 to 7 carbon atoms.   The insulating liquid according to claim 1, wherein the alcohol component has a branched alkyl group having 3 to 8 carbon atoms.   The insulating liquid according to claim 3, wherein the fatty acid monoester includes a product produced by a transesterification reaction between a natural fat and oil and a secondary alcohol or a tertiary alcohol.   The insulating liquid according to claim 1, wherein the fatty acid monoester contains an unsaturated fatty acid having 14 to 22 carbon atoms as a fatty acid component.   2. The relation of 1 ≦ X / Y ≦ 19 is satisfied, where the content of the fatty acid triglyceride in the insulating liquid is X [wt%] and the content of the fatty acid monoester is Y [wt%]. The insulating liquid according to any one of 5 to 5.   The insulating liquid according to claim 1, comprising a hydrolysis inhibitor having a function of suppressing hydrolysis of the fatty acid triglyceride and the fatty acid monoester.   The insulating liquid according to claim 7, wherein a content of the hydrolysis inhibitor in the insulating liquid is 0.01 to 5.0 wt%.   The insulating liquid according to claim 7 or 8, wherein the hydrolysis inhibitor is a phenol phosphite compound.   Toner particles mainly composed of a resin material and an insulating liquid, and the insulating liquid includes a fatty acid triglyceride and a fatty acid monoester, and the fatty acid triglyceride and the fatty acid monoester are not fatty acid components. A liquid developer containing a saturated fatty acid, wherein the alcohol component constituting the fatty acid monoester has an alkyl group having 1 to 8 carbon atoms.   The liquid developer according to claim 10, wherein an acid value of a resin material constituting the toner particles is 0.1 to 15 mg KOH / g.   The toner particles contain a fatty acid triglyceride and a fatty acid monoester, the fatty acid triglyceride and the fatty acid monoester contain an unsaturated fatty acid as a fatty acid component, and the alcohol component constituting the fatty acid monoester has a carbon number Pulverizing and / or crushing in an insulating liquid having an alkyl group of 1-8. A liquid developer reservoir for storing the liquid developer;
A developing unit for developing using the liquid developer supplied from the liquid developer storage unit;
A transfer unit that transfers the image formed by the developing unit onto a recording medium and forms a transfer image;
A collecting unit for collecting the liquid developer remaining in the developing unit and / or the transfer unit;
A transport unit configured to transport the liquid developer recovered from the recovery unit to the liquid developer storage unit;
A fixing unit for fixing the transfer image formed on the recording medium onto the recording medium,
The liquid developer includes toner particles mainly composed of a resin material, and an insulating liquid. The insulating liquid includes a fatty acid triglyceride and a fatty acid monoester, and the fatty acid triglyceride and the fatty acid monoester are An image forming apparatus comprising an unsaturated fatty acid as a fatty acid component, wherein the alcohol component constituting the fatty acid monoester has an alkyl group having 1 to 8 carbon atoms.   The image forming apparatus according to claim 13, further comprising an insulating liquid replenishing portion that replenishes the liquid developer storage portion with the insulating liquid according to claim 1.

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