JP5958351B2 - Fixing solution and electrophotographic image forming method - Google Patents

Description

  The present invention relates to a fixing solution used in an electrophotographic wet-fixing type image forming method and an electrophotographic image forming method using the fixing solution.

2. Description of the Related Art Image forming apparatuses such as printers, facsimile machines, and copiers are apparatuses that form images including characters and symbols on image supports such as paper, cloth, and OHP sheets based on image information.
In particular, an electrophotographic image forming apparatus can form high-definition images on plain paper at high speed, and is therefore widely used in offices, for example. In such an electrophotographic image forming apparatus, the toner constituting the toner image on the image support is heated and melted, and the melted toner is pressurized to fix the toner image on the image support. The thermal fixing method is widely used. This thermal fixing method can provide high fixing speed and high image quality.

  However, about half or more of the power consumption in such a heat fixing type image forming apparatus is consumed for heating the toner. On the other hand, from the viewpoint of countermeasures for environmental problems in recent years, a fixing method with low power consumption (energy saving) is desired. That is, there is a demand for a fixing method that does not require drastically lowering the temperature at which the toner is heated in order to fix the toner, or heating the toner. In particular, a non-heat fixing method in which a toner image is fixed on an image support without heating the toner is ideal in terms of low power consumption.

As a non-heat fixing method, there is known a wet fixing method in which a fixing liquid containing a softening agent that softens toner is supplied to a toner image and fixed on an image support. However, there are some problems in the wet fixing method.
For example, in order to obtain high fixing strength, when a large amount of fixing liquid is applied on an image support such as paper, the toner particles constituting the toner image flow on the image support due to excessive fixing liquid, resulting in image quality deterioration. And the problem that the drying time is prolonged and the fixing responsiveness is lowered (see Patent Document 1). In addition, there is a problem that a noticeable residual liquid feeling (stickiness when the paper is touched by hand) occurs on the paper.

  For example, when an oil-in-water type in which an organic compound (softener) insoluble or hardly soluble in water is dispersed and mixed in water (diluent) is used as the fixing solution, a large amount of fixing solution is used. When supplied, the image support such as paper absorbs moisture of the fixing solution, and wrinkles and curls are generated on the image support. As a result, there is a problem in that the transportability of the stable and high-speed image support required for the image forming apparatus is reduced (see Patent Document 2).

  Therefore, when fixing the toner image while minimizing the amount of fixing liquid while maintaining the fixing strength, the amount of fixing liquid applied per unit area is reduced, so the fixing liquid is uniformly applied to the toner image. Can not be supplied to. In particular, as disclosed in the above-mentioned Patent Document 2, when water is used as a diluent, since water has a high surface tension, wettability is deteriorated, and a fixing solution can be uniformly supplied to a toner image. The image defect that a part of the image cannot be missed becomes a problem.

Japanese Patent No. 4358896 Japanese Patent No. 3290513

  The present invention has been made in view of the above problems and situations, and a solution to the problem is that the amount of the fixing liquid supplied can be reduced while maintaining the fixing strength, and the toner image can be supplied uniformly. Therefore, it is possible to form a good image without image defects. It is another object of the present invention to provide a fixing solution and an electrophotographic image forming method that can increase the fixing speed and the drying speed, and can reduce stickiness in the formed image.

In order to solve the above problems, the present inventor, in the process of examining the cause of the above problems, the softener is an ester compound having a hydroxy group, and the diluent is a substance having a lower surface tension than the softener. Thus, it has been found that the fixing solution can be uniformly supplied to the toner image while reducing the supply amount of the fixing solution while maintaining the fixing strength, and as a result, a good image can be formed. It is up to.
That is, the said subject which concerns on this invention is solved by the following means.
1. A fixing liquid for fixing a toner image composed of toner on an image support by softening the toner,
Contains at least a softener and a diluent,
The softener is a compound represented by the following general formula (1):
_A fixing solution characterized by satisfying the following formulas (2) and (3) when the surface tension at 20 ° C. of the softener and the diluent is γ _A and γ _B (mN / m), respectively.
Formula (1): R ¹ —COO—R ²
[In General Formula (1), R ¹ and R ² represent a linear or branched aliphatic hydrocarbon group, aryl group or heterocyclic group having 1 to 15 carbon atoms which may have a substituent, and R ¹ And at least one of R ² has a hydroxy group. ]
Formula (2): γ _B <γ _A
Formula (3): γ _B ≦ 30

2. 2. The fixing solution according to claim 1, wherein a surface tension γ _B (mN / m) of the diluent satisfies the following formula (4).
Formula (4): 20 ≦ γ _B ≦ 30

3. An electrophotographic image forming method having at least an electrostatic latent image forming step, a developing step, a transfer step, and a fixing solution supplying step,
An electrophotographic image forming method, wherein the fixing solution according to item 1 or 2 is used as a fixing solution for softening toner in the fixing solution supply step.

4). 4. The electrophotographic image forming method according to claim 3, wherein the toner comprises toner particles containing a polyester resin or a styrene acrylic resin as a binder resin.

By the above means of the present invention, it is possible to reduce the supply amount of the fixing solution while maintaining the fixing strength and to supply the toner image uniformly, and as a result, it is possible to form a good image without image defects. In addition, it is possible to provide a fixing solution and an electrophotographic image forming method that can increase the fixing speed and the drying speed, and can reduce stickiness in the formed image.
The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.
In the fixing solution of the present invention, since the relationship between the surface tension γ _A of the softener and the surface tension γ _B of the diluent satisfies the above formulas (2) and (3), the surface tension as the fixing solution is decreased. The fixing liquid can be wetted and spread on the toner image within a good range, and even a small amount of a softening agent can be uniformly supplied onto the toner image. As a result, the toner swollen by contact with the softening agent forms a uniform image surface, and as a result, the voids on the image support are covered with the toner, and a good image can be formed. Further, since the supply amount of the fixing liquid can be reduced, it is considered that the fixing speed and the drying speed are increased, and the sticky feeling is reduced in the formed image.
Further, when the compound represented by the general formula (1) is contained as a softening agent, when the fixing solution is supplied to the toner image, the intramolecular structure of the compound represented by the general formula (1) The ester bond (group) of the toner and the toner molecule are affinityd by an intermolecular hydrogen bond, the toner particles are softened, and the hydroxy group in the molecule of the compound represented by the general formula (1) and the toner molecule It is considered that the softening of the toner particles is promoted by intermolecular hydrogen bonding. Further, the toner particles softened by intermolecular hydrogen bonding between the hydroxyl group in the molecule of the compound represented by the general formula (1) and the fiber cellulose of the image support such as paper are adsorbed to the paper fiber and are high. Adhesiveness is considered to be obtained. That is, since these hydrogen bonds are considered to be effective in “softening of toner particles” and “affinity (adhesion) with paper”, also in this respect, the fixing speed and the fixing speed are reduced. Higher drying speed is realized, and the stickiness in the formed image is reduced and the fixing strength is high. The softening of the toner particles by the hydroxy group is considered to be the same mechanism (solvation) as, for example, low-molecular alcohol or THF (tetrahydrofuran) dissolves the toner resin.

Cross-sectional view for explaining an example of the configuration of a fixing solution supply means used when supplying the fixing solution of the present invention FIG. 7 is a cross-sectional view for explaining an example of the configuration of a fixing solution supply unit and a pressure applying unit used when supplying the fixing solution of the present invention. Sectional drawing for description which shows the other example of a structure of the fixing solution supply means used when supplying the fixing solution of this invention Sectional drawing for description which shows the further another example of a structure of the fixing solution supply means used when supplying the fixing solution of the present invention Sectional drawing for description which shows the further another example of a structure of the fixing solution supply means used when supplying the fixing solution of the present invention Schematic showing an example of the configuration of an image forming apparatus used in the electrophotographic image forming method of the present invention

The fixing solution of the present invention is a fixing solution for fixing a toner image composed of toner on an image support by softening the toner, and contains at least a softening agent and a diluent. It is a compound represented by the general formula (1), and when the surface tension at 20 ° C. of the softener and the diluent is γ _A and γ _B (mN / m), respectively, the above formula (2) and formula (3) is satisfied.
This feature is a technical feature common to the inventions according to claims 1 to 4.

As an embodiment of the present invention, from the viewpoint of manifesting the effect of the present invention, it is possible that the surface tension γ _{B of the} diluent satisfies the above formula (4) to improve the wettability to the toner image. It is preferable in that it can be performed.

The electrophotographic image forming method of the present invention is an electrophotographic image forming method having at least an electrostatic latent image forming step, a developing step, a transferring step, and a fixing solution supplying step, wherein the toner is softened in the fixing solution supplying step. As the fixing solution to be used, the softener is a compound represented by the above general formula (1), and the surface tensions of the softener and the diluent at 20 ° C. are γ _A and γ _B (mN / m), respectively. In this case, a fixing solution satisfying the above formulas (2) and (3) is used. Accordingly, it is possible to uniformly supply the toner image by reducing the supply amount of the fixing solution while maintaining the fixing strength. As a result, it is possible to form a good image free from image defects, to increase the fixing speed and the drying speed, and to reduce stickiness in the formed image.

  Further, the toner is composed of toner particles containing a polyester resin or a styrene acrylic resin as a binder resin, thereby improving the affinity with the fixing solution and paper (faster fixing speed), improving the fixing strength, and feeling of stickiness. It is preferable at the point which can make suppression of both compatible.

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

[Fixing solution]
The fixing solution of the present invention is used in a wet fixing type image forming method, and is constituted by the toner by dissolving or swelling at least a part of the binder resin contained in the toner particles constituting the toner and softening. The toner image to be fixed is fixed to the image support. The fixing solution of the present invention contains at least a softener and a diluent, and the softener is a compound represented by the following general formula (1) (hereinafter also referred to as an ester compound represented by the general formula (1)). When the surface tensions of the softener and diluent at 20 ° C. are γ _A and γ _B (mN / m), respectively, the following expressions (2) and (3) are satisfied.
Formula (1): R ¹ —COO—R ²
[In General Formula (1), R ¹ and R ² represent a linear or branched aliphatic hydrocarbon group, aryl group or heterocyclic group having 1 to 15 carbon atoms which may have a substituent, and R ¹ And at least one of R ² has a hydroxy group. ]
Formula (2): γ _B <γ _A
Formula (3): γ _B ≦ 30
The fixing solution of the present invention contains the above softener and diluent as essential components, and may contain other components such as a dispersant as necessary.

<Softener>
The fixing liquid of the present invention contains a softening agent that dissolves or swells at least a part of the binder resin contained in the toner particles constituting the toner.
The softener used in the present invention is an ester compound represented by the general formula (1). The ester compound represented by the general formula (1) is an ester compound of hydroxycarboxylic acid (hydroxyalkanoate) or an ester compound of carboxylic acid, and a dehydration condensation reaction between a carboxylic acid having a hydroxyl group and an alcohol or a carboxylic acid It is obtained by a dehydration condensation reaction with a polyhydric alcohol having two or more hydroxyl groups.

In the general formula (1), R ¹ and R ² represent a linear or branched aliphatic hydrocarbon group, aryl group or heterocyclic group having 1 to 15 carbon atoms which may have a substituent, and R ^At least one of ¹ and R ² has a hydroxy group.
Examples of the substituent that can be substituted with a linear or branched aliphatic hydrocarbon group, aryl group or heterocyclic group having 1 to 15 carbon atoms include alkyl groups, alkynyl groups, alkenyl groups, alkoxy groups, alkoxyalkyl groups, and halogen groups. , Hydroxy group, amino group, nitro group, nitroso group, azo group, diazo group and the like.
Examples of the aryl group include cyclic substituents derived from aromatic hydrocarbons such as a phenyl group, a benzyl group, and a tolyl group.
Examples of the heterocyclic group include cyclic functional groups composed of two or more elements such as azole, oxole, and thiol.
Among these, an unsubstituted straight-chain or branched aliphatic hydrocarbon group having 1 to 15 carbon atoms is preferable in that the viscosity and boiling point can be adjusted without changing the affinity with toner and paper.
R ¹ is preferably a linear or branched alkyl group having 5 carbon atoms. R ² is preferably a linear or branched alkyl group having 2 carbon atoms.
The ester compound represented by the general formula (1), specifically, ethyl lactate as an ester compound of a hydroxycarboxylic acid, lactic acid isoamyl, 3-hydroxybutyrate, ethyl 2-hydroxybutyrate, methyl 2-hydroxyisobutyrate , Ethyl 3-hydroxyvalerate, ethyl 2-hydroxyvalerate, ethyl 2-hydroxy-4-methylvalerate, ethyl 3-hydroxyhexanoate, ethyl 2-hydroxyhexanoate, ethyl 5-hydroxyhexanoate, 3-hydroxy Examples thereof include ethyl octoate and ethyl 5-hydroxyoctanoate, and hydroxypropyl caprylate and hydroxy laurate as a hydroxyl group-containing ester compound obtained by a dehydration condensation reaction between a carboxylic acid and a polyhydric alcohol having two or more hydroxyl groups. Propyl, enanthate hydride Roxypropyl, or the compounds (A-6 to A-16) having the structures shown in the following (i) to (iv) are mentioned. These can be used individually by 1 type or in combination of 2 or more types.

(I) Compound example of R ¹ —COO—R ² in which R ¹ and R ² are branched aliphatic hydrocarbon groups

(Ii) examples of the compound R ¹ -COO-R ² R ¹ and R ² is a linear aliphatic hydrocarbon radical

(Iii) Compound of R ¹ -COO-R ² R ¹ and R ² are aryl groups Examples

(Iv) Compound examples of R ¹ —COO—R ² wherein R ¹ and R ² are heterocyclic groups

In the present invention, the ester compound represented by the general formula (1) preferably has a hydroxy group located at the β-position relative to the carbonyl group in R ¹ in the general formula (1). Since the hydroxy group is located at the β-position with respect to the carbonyl group, the carbonyl group and the hydroxy group are easily located on the same side (same plane) in terms of molecular skeleton (stereoscopic). It is thought that a large number of hydrogen bond formations with the toner or fiber cellulose per molecule of the ester compound represented by This is not limited to the β position, and the σ position is considered to show the same tendency. On the other hand, when the hydroxy group is located at the α-position, the carbonyl group and the hydroxy group are likely to face each other, so the number of hydrogen bonds with the toner or fiber cellulose is considered to be smaller than that at the β-position. In view of the above, the structure in which the hydroxy group is located at the β-position is preferable because the affinity between the fixing solution, the toner and the image support is considered to be high.

The ester compound represented by the general formula (1) is preferably contained in a proportion within a range of 5 to 50% by mass, more preferably within a range of 10 to 30% by mass with respect to the fixing solution.
When the content ratio of the ester compound represented by the general formula (1) is within the above range, high affinity for the binder resin contained in the toner particles can be obtained, and high fixing strength and fixing speed can be obtained. At the same time, the sticky feeling after fixing is suppressed.

<Diluent>
The fixing solution of the present invention contains a diluent for diluting and dispersing the ester compound represented by the general formula (1).
The diluent used in the present invention satisfies the formulas (2) and (3) when the surface tension at 20 ° C. of the softener and the diluent is γ _A and γ _B (mN / m), respectively.
Formula (2): γ _B <γ _A
Formula (3): γ _B ≦ 30
By mixing a diluent having a surface tension lower than that of the softening agent, particularly a diluent having a sufficiently low surface tension of 30 mN / m or less, the surface tension as the fixing solution is lowered, and the fixing solution is applied onto the toner image. Can be spread in a good range.
In addition, when the fixing solution is supplied by a nozzle, such as by coating with an inkjet, if the fixing solution is excessively lowered in surface tension, it is difficult to form a uniform liquid at the nozzle portion, and the difficulty of supplying a stable solution increases. Therefore, it is more preferable that the surface tension γ _{B of the} diluent satisfies the formula (4).
Formula (4): 20 ≦ γ _B ≦ 30
The method for measuring surface tension is described in general interface chemistry and colloid chemistry reference books. Specifically, the Wilhelmy method (for example, Kyowa Interface Chemical Co., Ltd., surface Tension meter CBVP-Z type).
Specific examples of such diluents include, for example, alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol Ether compounds such as diethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ester compounds such as allyl acetate, butyl acetate, ethyl propionate, ethyl butyrate, ethyl valerate, diethylene glycol monobutyl ester, polydimethylsiloxane And hydrocarbon solvents such as silicone oil and isoparaffin. These can be used individually by 1 type or in combination of 2 or more types.
The diluent is preferably contained in a proportion in the range of 50 to 95% by mass with respect to the fixing solution, and more preferably in the range of 70 to 90% by mass.

<Dispersant>
In the fixing solution of the present invention, a dispersant may be contained as necessary to improve the solubility or dispersibility of the ester compound represented by the general formula (1) in the diluent.
Examples of the dispersant used in the present invention include a surfactant, specifically, an anionic surfactant, a cationic surfactant, and a nonionic surfactant.
Examples of the anionic surfactant as the activator include higher fatty acid salts such as sodium laurate, sodium myristate, and sodium oleate; alkyl aryl sulfonates such as sodium dodecylbenzenesulfonate; alkyl such as sodium lauryl sulfate Sulfate esters; polyoxyethylene alkyl ether sulfate salts such as sodium polyethoxyethylene lauryl ether sulfate; polyoxyethylene alkyl aryl ether sulfate salts such as sodium polyoxyethylene nonylphenyl ether sulfate; sodium monooctylsulfosuccinate, dioctylsulfosuccinate Alkylsulfosuccinic acid ester salts such as sodium acid, sodium polyoxyethylene lauryl sulfosuccinate, and the like And the like derivatives.
Examples of the cationic surfactant include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts, and the like.
Examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether, polyoxyethylene alkyl phenyl ethers such as polyoxyethylene nonylphenyl ether, and sorbitan monolaurate. Sorbitan higher fatty acid esters such as sorbitan monostearate and sorbitan trioleate; polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate; polyoxyethylene monolaurate, polyoxyethylene monostearate and the like Polyoxyethylene higher fatty acid esters; glycerol higher fatty acid esters such as oleic acid monoglyceride and stearic acid monoglyceride Polyoxyethylene - polyoxypropylene - block copolymers, sucrose esters such as sucrose laurate ester and sucrose stearic acid ester, and the like.

  The dispersant is preferably contained at a ratio in the range of 0 to 10% by mass, more preferably in the range of 1 to 5% by mass with respect to the fixing solution.

[Supply amount of fixer]
The supply amount of the fixing solution of the present invention is, for example, preferably 0.4 g or less, more preferably 0.1 g or less per A4 size image support.

[Method for producing fixing solution]
As a method for producing the fixing solution of the present invention, for example, an ester compound represented by the general formula (1) and a dispersant as necessary are sequentially added to a fixing solution supply tank, and then the above-described diluent is added. And stirring at room temperature. Thereby, the fixing solution containing the ester compound represented by the general formula (1) can be prepared.

[Fixing liquid supply method]
Examples of the method for supplying the fixing solution of the present invention include a method of spraying, spraying or applying the fixing solution in a liquid or foam form using a fixing solution supply unit.
Examples of the fixing liquid supply unit include an inkjet nozzle, a sprayer using an ultrasonic vibrator, a sprayer using compressed air, a sprayer that electrostatically drops liquid droplets, or a roller.

Hereinafter, the fixing solution supply method of the present invention will be described in detail.
FIG. 1 is an explanatory cross-sectional view showing an example of the configuration of a fixing solution supply means used when supplying the fixing solution of the present invention.
The fixing liquid supply unit 50A is composed of a line-type inkjet nozzle, and is disposed on the downstream side of the toner image carrier 31.
In such a fixing solution supply means 50A, the droplets of the fixing solution F are supplied to the toner image T according to the region of the toner image T transferred onto the image support P.

It is preferable that the line type ink jet constituting the fixing solution supply unit 50A has a resolution of 300 dpi or more. Moreover, it is preferable that the droplet size of an inkjet is in the range of 0.5-50 pl.
In the case where an ink jet nozzle is used as the fixing solution supply means 50A, the fixing solution needs to have solvent resistance.
Further, when the fixing solution is not liquid at room temperature or higher, or when the viscosity of the fixing solution is high, a heater may be provided in the fixing solution supply unit 50A.

In addition, it is preferable to perform a pressure applying step of applying a pressure to the toner image T supplied with the fixing solution F after the fixing solution supplying step. Specifically, as shown in FIG. 2, after the fixing liquid supply step, pressure is applied to the toner image T supplied with the fixing liquid F by the pressure applying means 70 including a pair of pressure rollers. I can.
As the pressure applying means, for example, a roller having a releasable surface can be used. The applied pressure is not particularly limited, but is preferably in the range of 50 kPa to 1 MPa, for example.
By performing this pressure application step, higher fixing strength can be obtained in the formed image.

FIG. 3 is an explanatory cross-sectional view showing another example of the configuration of the fixing solution supply means used when supplying the fixing solution of the present invention.
The fixing solution supply means 50 </ b> B includes a fixing solution application roller 51 and a pressure roller 52 provided to face the fixing solution application roller 51. A part of the fixing liquid application roller 51 is immersed in, for example, a liquid fixing liquid F. Further, a metering blade 53 for controlling the amount of the fixing liquid F to be supplied onto the toner image T is provided in a state in which the tip portion is separated from the surface of the fixing liquid application roller 51.
In such a fixing liquid supply means 50B, the fixing liquid F is rotated by the fixing liquid application roller 51 and the pressure roller 52, and the supply amount of the liquid fixing liquid F on the fixing liquid application roller 51 is metered. While being regulated by the blade 53, the liquid film M is supplied to the entire surface of the image support P onto which the toner image T has been transferred, and pressure is applied by the pressure roller 52.
Although the film thickness of the liquid film M is not specifically limited, For example, the inside of the range of 1-100 micrometers is preferable.
Further, the pressing force of the pressure roller 52 is preferably within a range of 150 to 250 MPa, for example.

FIG. 4 is an explanatory sectional view showing still another example of the configuration of the fixing solution supply means used when supplying the fixing solution of the present invention.
The fixing liquid supply means 50C includes a foam generating device 54 that jets the fixing liquid in a foam form, a fixing liquid application roller 55, and a pressure roller 56 provided to face the fixing liquid application roller 55. Is done. Further, a regulating blade 57 for controlling the amount of the fixing liquid F to be supplied onto the toner image T is provided in a state where the tip portion is separated from the surface of the fixing liquid application roller 55.
In such a fixing liquid supply means 50C, the supply amount of the fixing liquid F is controlled by the rotational driving of the fixing liquid application roller 55 and the pressure roller 56, and the supply amount of the foam-like fixing liquid F on the fixing liquid application roller 55 is regulated. While being regulated by the blade 57, the whole surface of the image support P onto which the toner image T has been transferred is supplied as a foam film B, and pressure is applied by the pressure roller 56.
Although the film thickness of the foam film | membrane B is not specifically limited, For example, the inside of the range of 50-80 micrometers is preferable.
Further, the pressure applied by the pressure roller 56 is preferably in the range of 150 to 250 MPa, for example.

FIG. 5 is an explanatory sectional view showing still another example of the configuration of the fixing solution supply means used when supplying the fixing solution of the present invention.
The fixing liquid supply unit 50D is a sprayer using compressed air, and is disposed on the downstream side of the toner image carrier 31.
In such a fixing solution supply means 50D, the liquid fixing solution F is sprayed and supplied to the toner image T transferred onto the image support P.

  According to the fixing solution of the present invention, the fixing solution contains a softening agent and a diluent, and the relationship between the surface tension of the softening agent and the diluent at 20 ° C. is expressed by the above formulas (2) and (3), and When the softener contains the ester compound represented by the general formula (1), it is possible to uniformly supply the toner image by reducing the supply amount of the fixing solution while maintaining the fixing strength. A good image free from image defects can be formed. In addition, it is possible to increase the fixing speed and the drying speed, and it is possible to reduce stickiness in the formed image.

[Electrophotographic image forming method]
The electrophotographic image forming method of the present invention includes at least an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image carrier, and a toner containing at least a binder resin. A developing process for forming a toner image by developing with a dry developer, a transfer process for transferring the toner image to the image support, and a fixing liquid for softening the toner to the toner image transferred to the image support A fixing solution supply step, and the fixing solution of the present invention is used as the fixing solution.

[Electrostatic latent image forming process]
The electrostatic latent image forming step is a step of forming an electrostatic latent image on the electrostatic latent image carrier.
The electrostatic latent image carrier used in the present invention is not particularly limited, but for example, an inorganic photoreceptor such as amorphous silicon or selenium, or a drum-like body composed of an organic photoreceptor such as polysilane or phthalopolymethine. Things.
The electrostatic latent image is formed, for example, by uniformly charging the surface of the electrostatic latent image carrier with a charging unit and exposing the surface of the electrostatic latent image carrier imagewise with an exposure unit.
The charging means and the exposure means are not particularly limited, and those generally used in electrophotography can be used.

[Development process]
The developing step is a step of forming a toner image by developing the electrostatic latent image with a dry developer containing toner composed of toner particles containing at least a binder resin.
The toner image is formed using a dry developer containing toner, for example, using a developing unit including a stirrer that frictionally stirs and charges the toner and a rotatable magnet roller. Specifically, in the developing unit, for example, the toner and the carrier are mixed and stirred, and the toner is charged by friction at that time, and is held on the surface of the rotating magnet roller, thereby forming a magnetic brush. Since the magnet roller is arranged in the vicinity of the electrostatic latent image carrier, a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is part of the electrostatic latent image carrier by the electric attractive force. Move to the surface. As a result, the electrostatic latent image is developed with toner, and a toner image is formed on the surface of the electrostatic latent image carrier.

<Toner>
The toner used in the electrophotographic image forming method of the present invention is composed of toner particles containing at least a binder resin. The toner particles may contain an internal additive such as a colorant, a release agent, a magnetic powder, and a charge control agent, if necessary, and an external additive such as a fluidizing agent may be added to the toner particles. An additive may be externally added.

The toner used in the electrophotographic image forming method of the present invention preferably has a particle size in the range of 3.5 to 7.0 μm, more preferably 5.0 to 6.5 μm in terms of volume-based median diameter. Within range.
Since the volume-based median diameter of the toner is within the above range, the specific surface area of the toner is sufficiently ensured, and therefore, the contact area with the fixing solution is sufficiently ensured in the fixing solution supplying process described later. The toner image can be surely fixed on the image support, whereby a sufficient fixing strength can be obtained in the formed image.

In the present invention, the volume-based median diameter of the toner is obtained by using a measuring device in which a computer system equipped with data processing software “Software V3.51” is connected to “Coulter Multisizer 3” (manufactured by Beckman Coulter). Measured and calculated.
Specifically, 0.02 g of a sample (toner) was added to 20 mL of a surfactant solution (for example, a surfactant solution in which a neutral detergent containing a surfactant component was diluted 10 times with pure water for the purpose of dispersing toner particles. ), And ultrasonic dispersion is performed for 1 minute to prepare a dispersion, and this dispersion is measured in a beaker containing “ISOTONII” (manufactured by Beckman Coulter) in the sample stand. Pipette until the indicated concentration on the device is 8%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measuring apparatus, the measurement particle count number is 25000, the aperture diameter is 50 μm, the frequency value is calculated by dividing the range of 1 to 30 μm, which is the measurement range, into 256 parts, and from the larger volume integrated fraction A particle size of 50% is defined as a volume-based median diameter.

  The toner used in the electrophotographic image forming method of the present invention preferably has an average circularity in the range of 0.930 to 1.000, more preferably 0.950 to from the viewpoint of improving transfer efficiency. It is in the range of 0.995.

In the present invention, the average circularity of the toner is measured using “FPIA-2100” (manufactured by Sysmex).
Specifically, the sample (toner) was blended with a surfactant-containing aqueous solution, subjected to ultrasonic dispersion treatment for 1 minute to disperse, and then subjected to measurement condition HPF (“PFIA-2100” (manufactured by Sysmex)). In the high magnification imaging mode, photographing is performed at an appropriate density of 3,000 to 10,000 HPF detections, and the circularity of each toner particle is calculated according to the following formula (T). Is calculated by dividing by the total number of toner particles.
Formula (T): Circularity = (peripheral length of a circle having the same projected area as a particle image) / (peripheral length of a particle role image)

  The toner used in the electrophotographic image forming method of the present invention preferably has a glass transition point in the range of 30 to 70 ° C., more preferably 35 to 50 ° C. from the viewpoints of heat resistant storage resistance and blocking resistance. Is within the range.

In the present invention, the glass transition point of the toner is measured using a differential scanning calorimeter “DSC8500” (manufactured by PerkinElmer).
Specifically, 4.5 mg of sample (toner) is precisely weighed to two digits after the decimal point, sealed in an aluminum pan, and set in a DSC-7 sample holder. For the reference, an empty aluminum pan was used, and heat-cool-heat temperature control was performed at a measurement temperature of 0 to 200 ° C., a temperature increase rate of 10 ° C./min, and a temperature decrease rate of 10 ° C./min. Analysis is performed based on the data in Heat. The glass transition point is defined as the value of the intersection of the extension line of the base line before the rise of the first endothermic peak and the tangent line indicating the maximum slope between the rising portion of the first endothermic peak and the peak apex.

  The toner used in the electrophotographic image forming method of the present invention preferably has a softening point in the range of 90 to 120 ° C., more preferably in the range of 100 to 115 ° C. from the viewpoint of fixing strength.

In the present invention, the softening point of the toner is measured as follows.
That is, in an environment of a temperature of 20 ± 1 ° C. and a humidity of 50 ± 5% RH, 1.1 g of a sample (toner) is placed in a petri dish and flattened and left to stand for 12 hours or more, and then the molding machine “SSP-10A” ( Pressed with a force of 3820 kg / cm ² for 30 seconds by Shimadzu Corporation to make a cylindrical molded sample with a diameter of 1 cm. Next, this molded sample was subjected to a load of 196 N (20 kgf), a starting temperature of 60 ° C. and a preheating by a flow tester “CFT-500D” (manufactured by Shimadzu Corporation) in an environment of a temperature of 24 ± 5 ° C. and a humidity of 50 ± 20% RH. Extruding from the hole of the cylindrical die (1 mm diameter x 1 mm) using a piston with a diameter of 1 cm from the end of preheating under the condition of a heating rate of 6 ° C / min for 300 seconds, It is measured using the offset temperature T _offset measured at the setting of the offset value of 5 mm as the softening point.

(Binder resin)
Examples of the binder resin contained in the toner particles according to the present invention include styrene resin, (meth) acrylic resin, styrene- (meth) acrylic resin, polyester resin, polyether polyol resin, and polyvinyl acetate resin. Well-known various resin is mentioned. Among these, styrene- (meth) acrylic resin or polyester resin is preferable from the viewpoint of affinity with the softening agent.

  When a styrene resin, (meth) acrylic resin, or styrene- (meth) acrylic resin is used as the binder resin, examples of the polymerizable monomer that should form the binder resin include styrene and o-methylstyrene. , M-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn -Styrene or styrene derivatives such as octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, methacryl Isobutyl acid, t-butyl methacrylate, n-octyl methacrylate , Methacrylate esters such as 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, isopropyl acrylate, acrylic acid acrylic acid ester derivatives such as n-butyl, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, etc .; olefins such as ethylene, propylene, isobutylene; acrylonitrile, methacrylo Examples thereof include vinyl monomers such as acrylic acid or methacrylic acid derivatives such as nitrile and acrylamide. These vinyl monomers can be used alone or in combination of two or more.

Further, it is preferable to use a combination of the polymerizable monomer having an ionic dissociation group as the polymerizable monomer for forming the binder resin. The polymerizable monomer having an ionic dissociation group has, for example, a substituent such as a carboxy group, a sulfonic acid group, and a phosphoric acid group as a constituent group, and specifically includes acrylic acid, methacrylic acid, maleic acid. Examples include acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrenesulfonic acid, allylsulfosuccinic acid, 2-acrylamido-2-methylpropanesulfonic acid, and the like.
Furthermore, as a polymerizable monomer, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, or neo A binder resin having a crosslinked structure can also be obtained using polyfunctional vinyls such as pentyl glycol diacrylate.

When a polyester resin is used as the binder resin, the polyester resin can be obtained from a known polyhydric alcohol and a known polyvalent carboxylic acid.
Examples of the polyhydric alcohol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8- Octanediol, 1,9-nonanediol, 1,10-dodecanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18- Aliphatic diols such as octadecanediol and 1,20-eicosanediol; bisphenols such as bisphenol A and bisphenol F; and alkylene oxide adducts of bisphenols such as ethylene oxide adducts and propylene oxide adducts. It is done. Examples of the trihydric or higher polyhydric alcohol include glycerin, pentaerythritol, trimethylolpropane, and sorbitol. Examples of the polyhydric alcohol having an unsaturated group include 2-butene-1,4-diol, 3-butene-1,6-diol, 4-butene-1,8-diol, and 9-octadecene-7,12. Those having an unsaturated double bond such as diol; those having an unsaturated triple bond such as 2-butyne-1,4-diol, 3-butyne-1,4-diol, and the like. These polyhydric alcohols can be used alone or in combination of two or more.
Examples of the polyvalent carboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelic acid, sebacic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid. Acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid Aliphatic carboxylic acids such as lower alkyl esters and anhydrides of these aliphatic carboxylic acids; phthalic acid, isophthalic acid, terephthalic acid, orthophthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4 Aromatic carboxylic acids such as' -biphenyldicarboxylic acid; trimet acid, pyromellitic acid Examples thereof include trivalent or higher polyvalent carboxylic acids such as toic acid. Examples of the polyvalent carboxylic acid having an unsaturated group include unsaturated fatty acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, isododecenyl succinic acid, n-dodecenyl succinic acid, and n-octenyl succinic acid. Carboxylic acids; and acid anhydrides or acid chlorides thereof; unsaturated aromatic carboxylic acids such as caffeic acid. These polyvalent carboxylic acids can be used alone or in combination of two or more.

  The polyester resin can be produced, for example, by subjecting the polyhydric alcohol and the polyhydric carboxylic acid to condensation polymerization at a temperature in the range of 120 to 250 ° C. in an inert gas atmosphere. In the condensation polymerization, a known esterification catalyst may be used as necessary.

When the styrene- (meth) acrylic resin is used, the ratio of the dissociated acid monomer in the binder resin is preferably in the range of 0 to 20%, more preferably in the range of 5 to 15%. When using resin, it is preferable to exist in the range of 10 to 50%, and more preferably in the range of 20 to 50%.

  The binder resin preferably has a glass transition point in the range of 30 to 70 ° C in terms of obtaining heat-resistant storage properties, and more preferably in the range of 35 to 45 ° C. By setting the glass transition point within the range of 30 to 70 ° C., heat resistant storage stability is obtained.

  In the present invention, the glass transition point of the binder resin is measured in the same manner except that the sample is used as the binder resin in the method for measuring the glass transition point of the toner described above.

  When the binder resin has a weight average molecular weight in the range of 3,000 to 100,000, the strength of the toner particles can be improved, toner scattering can be prevented, and high fixing strength can be obtained in the formed image. It is preferable at the point which is manufactured, More preferably, it exists in the range of 5,000-50,000.

In the present invention, the weight average molecular weight of the binder resin is measured by GPC.
Specifically, using an apparatus “HLC-8220” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn + TSKgelSuperHZM-M3 series” (manufactured by Tosoh Corporation), while maintaining the column temperature at 40 ° C., tetrahydrofuran (THF) was used as a carrier solvent. The sample is flowed at a flow rate of 0.2 mL / min, and the sample (binder resin) is dissolved in THF to a concentration of 1 mg / mL under a dissolution condition in which treatment is performed for 5 minutes using an ultrasonic disperser at room temperature. Next, a sample solution is obtained by processing with a membrane filter having a pore size of 0.2 μm, and 10 μL of this sample solution is injected into the apparatus together with the above carrier solvent, and is detected using a refractive index detector (RI detector). Is calculated using a calibration curve obtained by measuring monodisperse polystyrene standard particles. Ten polystyrenes are used for calibration curve measurement.

(Coloring agent)
When the toner particles according to the present invention contain a colorant, the colorant is not particularly limited, and a known pigment can be used.
Examples of the black colorant include carbon black such as furnace black, channel black, acetylene black, thermal black, or lamp black.
Examples of the magenta or red colorant include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48; 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, or C.I. I. And CI Pigment Red 222.
Examples of the orange or yellow colorant include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 100, or C.I. I. And CI Pigment Yellow 104.
Examples of the green or cyan colorant include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15; 2, C.I. I. Pigment blue 15; 3, C.I. I. Pigment blue 15; 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment blue 62, C.I. I. Pigment blue 66, or C.I. I. And CI Pigment Green 7.
These colorants can be used alone or in combination of two or more.

  The content ratio of the colorant is preferably in the range of 1 to 10 parts by mass, more preferably in the range of 2 to 9 parts by mass with respect to 100 parts by mass of the binder resin.

(Release agent)
In the case where the toner particles according to the present invention contain a release agent, examples of the release agent include wax, and specific examples include the following.
(1) Polyolefin wax Polyethylene wax, polypropylene wax, etc. (2) Long-chain hydrocarbon wax, paraffin wax, sazol wax, etc. (3) Dialkyl ketone wax, distearyl ketone, etc. (4) Ester wax Carnauba wax, Montan Wax, trimethylolpropane tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerol tribehenate, 1,18-octadecanediol di Stearate, behenyl behenate, stearyl stearate, tristearyl trimellitic acid, distearyl maleate, etc. (5) Amide wax Ethylene Diamine dibehenyl amide, trimellitic acid tristearyl amide, and the like.

  It is preferable that the content rate of a mold release agent exists in the range of 0-10 mass parts with respect to 100 mass parts of binder resin, More preferably, it exists in the range of 5-10 mass parts.

(Magnetic powder)
When the toner particles according to the present invention contain magnetic powder, examples of the magnetic powder include magnetite, γ-hematite, and various ferrites.
The content of the magnetic powder is preferably in the range of 10 to 500 parts by mass, more preferably in the range of 20 to 200 parts by mass with respect to 100 parts by mass of the binder resin.

(Charge control agent)
In the case where the toner particles according to the present invention contain a charge control agent, the charge control agent is not particularly limited as long as it is a substance that can give positive or negative charge by frictional charging. A positive charge control agent and a negative charge control agent can be used.
The content ratio of the charge control agent is preferably in the range of 0.1 to 10 parts by mass, more preferably in the range of 0.5 to 5 parts by mass with respect to 100 parts by mass of the binder resin.

(External additive)
The toner particles according to the present invention can be used as a toner as they are, but in order to improve fluidity, chargeability, cleaning properties, etc., an external additive such as a so-called fluidizing agent or cleaning aid is added to the toner particles. It can be used with the agent added.
Examples of the fluidizing agent include silica, alumina, titanium oxide, zinc oxide, iron oxide, copper oxide, lead oxide, antimony oxide, yttrium oxide, magnesium oxide, barium titanate, ferrite, bengara, magnesium fluoride, silicon carbide. Inorganic fine particles made of boron carbide, silicon nitride, zirconium nitride, magnetite, magnesium stearate, or the like.
These inorganic fine particles are surface treated with a silane coupling agent, a titanium coupling agent, a higher fatty acid, or silicone oil to improve the dispersibility of the toner particles on the surface and to improve environmental stability. Is preferred.
Examples of the cleaning aid include polystyrene fine particles or polymethyl methacrylate fine particles.
Various external additives can be used in combination.
The external additive preferably has an average primary particle size of 30 nm or less.
The addition ratio of the external additive is preferably in the range of 0.05 to 5 parts by mass, more preferably in the range of 0.1 to 3 parts by mass with respect to 100 parts by mass of the toner particles.

  Examples of the method for producing the toner as described above include known methods such as a dry method such as a pulverization method and a wet method such as an emulsion association method, a dissolution / dissolution method, or a dissolution suspension method.

(Dry developer)
The developer used in the electrophotographic image forming method of the present invention is a dry type, and even if it is a one-component developer composed only of magnetic or non-magnetic toner, a two-component formed by mixing toner and carrier It may be a developer.
In the case of a two-component developer, as the carrier, magnetic particles made of conventionally known materials such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead are used. In particular, ferrite particles are preferred. Further, as the carrier, a resin-coated carrier in which the surface of magnetic particles is coated with a coating agent such as a resin, a dispersed carrier in which a magnetic fine powder is dispersed in a binder resin, or the like may be used.

The carrier preferably has a volume-based median diameter in the range of 15 to 100 μm, and more preferably in the range of 20 to 80 μm.
The volume-based median diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

[Transfer process]
The transfer process is a process of transferring the toner image to the image support.
Transfer of the toner image to the image support is performed by peeling and charging the toner image to the image support.
As the transfer means, for example, a corona transfer device using corona discharge, a transfer belt, or a transfer roller can be used.
In addition, in the transfer step, for example, an intermediate transfer member is used, and after the toner image is primarily transferred onto the intermediate transfer member, the toner image is secondarily transferred onto the image support. The toner image formed above can also be transferred directly to the image support.

  The image support is not particularly limited, and is a plain paper from thin paper to thick paper, high-quality paper, coated printing paper such as art paper or coated paper, commercially available Japanese paper or postcard paper, and plastic film for OHP. Or various kinds of cloth.

[Fixing solution supply process]
The fixing solution supply step is a step of supplying a fixing solution for softening the toner to the toner image transferred to the image support, and the fixing solution used is the fixing solution of the present invention.

The electrophotographic image forming method of the present invention can be executed by, for example, the following image forming apparatus.
FIG. 6 is a schematic view showing an example of the configuration of an image forming apparatus used in the electrophotographic image forming method of the present invention.
The image forming apparatus 10 is a tandem type full-color image forming apparatus, and includes a plurality of image forming units 30Y, 30M, 30C, and 30K provided along the belt-like intermediate transfer body 20, and the intermediate transfer body 20. A secondary transfer means 40 for transferring the toner image formed by each image forming unit to the image support P, and a fixing liquid supply means 50 for supplying a fixing liquid to the toner image transferred onto the image support P. Is provided.

  The image forming unit 30Y forms a yellow toner image, and includes a drum-shaped photoconductor 31Y that is an electrostatic latent image carrier. Around the photoconductor 31Y, a charging unit 32Y, an exposure unit 33Y, The developing unit 34Y, the primary transfer unit 35Y, and the cleaning unit 36Y are arranged.

  The image forming units 30M, 30C, and 30K have the same configuration as that of the image forming unit 30Y, except that magenta, cyan, and black toner images are formed instead of forming yellow toner images.

  The intermediate transfer body 20 is stretched around a plurality of support rollers 21A, 21B, and 21C, and is supported so as to be able to circulate.

  The secondary transfer means 40 is composed of a transfer device that peels and charges the toner image onto the image support P.

  The fixing liquid supply means 50 supplies the fixing liquid to the toner image as droplets, and is composed of, for example, a line type ink jet nozzle.

In the image forming apparatus 10, the following image forming process is performed.
When the photoreceptor 31Y is rotationally driven in the image forming unit 30Y, the charging unit 32Y applies a uniform potential to the surface of the photoreceptor 31Y by corona discharge having the same polarity as the toner. An electrostatic latent image is formed on the surface of the uniformly charged photoreceptor 31Y based on the image data by scanning with exposure means 33Y parallel to the rotational direction of the photoreceptor 31Y and performing exposure. The
Next, the developing unit 34Y causes the toner charged to the same polarity as the surface potential of the photoconductor 31Y to adhere to the electrostatic latent image on the photoconductor 31Y and performs reversal development, whereby a toner image is formed and circulated. The image is transferred onto the moving intermediate transfer body 20 by the primary transfer means 35Y. These processes are also performed in the image forming units 30M, 30C, and 30K, and the color toner images formed by the image forming units 30Y, 30M, 30C, and 30K are superimposed on the intermediate transfer member 20 to be color toners. An image is formed. The color toner image is secondarily transferred by the secondary transfer unit 40 onto the image support P conveyed at a predetermined timing.
Next, the fixing liquid is supplied to the toner image secondarily transferred to the image support P by the fixing liquid device 50 based on the image data. The toner image supplied with the fixing liquid is fixed on the image support P to form an image.
On the other hand, after the color toner image is transferred to the image support P by the secondary transfer means 40, the cleaning means 60 removes the untransferred toner remaining on the intermediate transfer body 20 from which the image support P is separated by curvature. . In the cleaning units 36Y, 36M, 36C, and 36K, the untransferred toner remaining on the photoreceptors 31Y, 31M, 31C, and 31K is removed.

  According to the electrophotographic image forming method of the present invention, in the wet fixing method, by using the fixing solution of the present invention, the supply amount of the fixing solution is reduced and the toner image is uniformly supplied while maintaining the fixing strength. As a result, it is possible to form a good image without image defects. In addition, it is possible to increase the fixing speed and the drying speed, and it is possible to reduce stickiness in the formed image.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

[Preparation of Toner [1]]
(1) Preparation of binder resin particle dispersion [1] In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube and a nitrogen introducing device, 4 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate was ion-exchanged water. The solution was added together with 3040 parts by mass to prepare an aqueous surfactant solution, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. To this surfactant aqueous solution, a polymerization initiator solution in which 10 parts by mass of potassium persulfate was dissolved in 400 parts by mass of ion-exchanged water was added, the temperature was raised to 75 ° C., 479 parts by mass of styrene, n- A monomer solution consisting of 144 parts by mass of butyl acrylate, 77 parts by mass of methacrylic acid and 9 parts by mass of n-octyl mercaptan was dropped into the reaction vessel over 1 hour. After the dropping, polymerization was carried out by heating and stirring at 75 ° C. for 2 hours to prepare a binder resin particle dispersion [1] in which binder resin particles made of styrene-acrylic resin were dispersed. The prepared binder resin particles had a glass transition point of 56 ° C. and a weight average molecular weight of 23,000.

(2) Preparation of Colorant Particle Dispersion [1] While stirring an aqueous surfactant solution in which 90 parts by mass of sodium dodecyl sulfate was dissolved in 1600 parts by mass of ion-exchanged water, carbon black “Regal 330” (manufactured by Cabot) 400 parts by mass were gradually added, and dispersion treatment was performed using a stirrer “CLEARMIX” (manufactured by M Technique Co., Ltd.) to prepare a colorant particle dispersion [1] in which colorant particles were dispersed. The colorant particles were measured using an electrophoretic light scatterometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), and the particle size was 110 nm in terms of volume-based median diameter.

(3) Preparation of toner [1] In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube and a nitrogen introduction device, 420 parts by mass of binder resin particle dispersion [1] (in terms of solid content), ion-exchanged water 900 Part by mass and 200 parts by mass of the colorant particle dispersion [1] were added and stirred. After adjusting the temperature in a container to 30 degreeC, 5 mol / liter sodium hydroxide aqueous solution was added and pH was adjusted to 8-11.
Next, an aqueous solution in which 2 parts by mass of magnesium chloride hexahydrate was dissolved in 1000 parts by mass of ion-exchanged water was added with stirring at 30 ° C. over 10 minutes. The temperature was increased by allowing to stand for 3 minutes, and the system was heated to 65 ° C. over 60 minutes to associate the binder resin particles with the colorant particles. In this state, using “Coulter Multisizer 3” (manufactured by Coulter, Inc.), the particle size of the associated particles was measured, and when the volume-based median diameter reached 6.3 μm, 40.2 parts by mass of sodium chloride Was dissolved in 1000 parts by mass of ion-exchanged water to stop the association.
Thereafter, the liquid temperature was set to 70 ° C. as a shape control step, and the fusion was continued by heating and stirring for 1 hour. The average circularity of the particles at this time was 0.960 as measured by “FPIA2100” (manufactured by Systex). Further, the mixture is cooled to 30 ° C. at a rate of 8 ° C./min, filtered, washed repeatedly with ion exchange water at 45 ° C., and dried with warm air at 40 ° C. to obtain toner base particles [1]. It was. The toner base particle [1] had a volume-based median diameter of 6.5 μm.
To 100 parts by mass of the obtained toner base particles [1], 1 part by mass of hydrophobic silica was added and mixed with a Henschel mixer. The peripheral speed of the rotor blades was 24 m / s, and the mixture was mixed for 20 minutes, and then passed through a 400MESH sieve to obtain toner [1].

[Preparation of Toner [2]]
(1) Preparation of binder resin particle dispersion [2]-Ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.): 37 parts by mass-Neopentyl glycol (manufactured by Wako Pure Chemical Industries, Ltd.): 65 parts by mass- 1,9-nonanediol (manufactured by Wako Pure Chemical Industries, Ltd.): 32 parts by mass / terephthalic acid (manufactured by Wako Pure Chemical Industries, Ltd.): 96 parts by mass After raising the temperature to 200 ° C. and confirming that the reaction system was uniformly stirred, 1.2 parts by mass of dibutyltin oxide was added. Further, while distilling off the generated water, the temperature was raised from the same temperature to 240 ° C. over 6 hours, and the dehydration condensation reaction was continued at 240 ° C. for further 4 hours. The acid value was 9.4 mgKOH / g, and the weight average molecular weight. A polyester resin having 13,000 and a glass transition temperature of 62 ° C. was obtained. Next, this was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. A 0.37% by mass diluted ammonia water obtained by diluting reagent ammonia water with ion-exchanged water is placed in a separately prepared aqueous medium tank, and heated at 120 ° C. with a heat exchanger at a rate of 0.1 liter per minute. Simultaneously with the polyester resin melt, it was transferred to the Cavitron. A Cavitron is operated under the conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ² , dispersion of a resin having an average particle size of 160 nm, a solid content of 30%, a glass transition temperature of 62 ° C., and a weight average molecular weight Mw of 13,000. Liquid (binder resin particle dispersion [2] was obtained.

(2) Preparation of mold release agent dispersion [1] Paraffin wax: HNP-9 (Nippon Seiki Co., Ltd.): 19 parts by mass Anionic surfactant: Neogen SC (Daiichi Kogyo Seiyaku Co., Ltd.) Product): 1 part by mass / ion-exchanged water: 80 parts by mass The above components were mixed in a heat-resistant container, heated to 90 ° C., and stirred for 30 minutes. Next, the molten liquid is circulated from the bottom of the container to the gorin homogenizer, and under a pressure condition of 5 MPa, a circulation operation corresponding to 3 passes is performed, then the pressure is increased to 35 MPa, and further a circulation operation corresponding to 3 passes is performed. It was. The emulsion thus prepared was cooled in the heat-resistant solution to 40 ° C. or lower to obtain a release agent dispersion liquid [1].
(3) Preparation of toner [2] Binder resin particle dispersion [2]: 150 parts by weight Colorant particle dispersion [1]: 25 parts by weight Release agent dispersion [1]: 35 parts by weight Polyaluminum chloride: 0.4 parts by mass / ion exchange water: 100 parts by mass The above components were mixed and dispersed for 10 minutes in a round stainless steel flask using IKE Ultra Turrax T50, and then heated. The flask was heated from 30 ° C. to 48 ° C. at 3 ° C./min with stirring in the flask. After maintaining at 48 ° C. for 60 minutes, 70 parts by mass of the binder resin particle dispersion [2] was gradually added thereto. Then, after adjusting the pH in the system to 8.0 using a sodium hydroxide aqueous solution having a concentration of 0.5 mol / L, the stainless steel flask is sealed, and the stirring shaft seal is magnetically sealed while stirring is continued. Heated to 90 ° C. and held for 30 minutes. After completion of the holding, the temperature lowering rate was cooled at 5 ° C./min, filtered, washed with ion-exchanged water, and solid-liquid separation was performed by Nutsche suction filtration. This was further redispersed using 3,000 parts by mass of ion-exchanged water at 30 ° C., and stirred and washed at 300 rpm for 15 minutes. This washing operation was further repeated 6 times, and No. 1 was obtained by Nutsche suction filtration. Solid-liquid separation was performed using 5A filter paper. Next, vacuum drying was continued for 24 hours to obtain toner base particles [2].
The volume average particle size of the toner base particles [2] was measured with a Coulter Multisizer-II type (manufactured by Beckman Coulter, Inc.) and found to be 5.7 μm, and the volume average particle size distribution index GSDv was 1.22.
The toner base particles [2] thus obtained were externally added in the same manner as the toner [1] except that the toner base particles [1] were replaced with the toner base particles [1] to obtain a toner [2].

[Preparation of dry developer [1]]
The toner [1] was mixed with a ferrite carrier having a volume average particle diameter of 60 nm coated with a silicone resin to produce a dry developer [1] having a toner concentration of 6% by mass.

[Preparation of dry developer [2]]
A dry developer [2] was prepared in the same manner as the dry developer [1] except that the toner [1] in the dry developer [1] was replaced with the toner [2].

[Preparation of Fixing Solution [1]]
30 parts by mass of ethyl 3-hydroxyhexanoate as a softening agent and 70 parts by mass of ethylene glycol diethyl ether as a diluent were added and stirred for 5 minutes with a stirrer to prepare fixing solution [1].

なお、γ_Aとγ_B（ｍＮ／ｍ）は、それぞれ軟化剤と希釈剤の２０℃における表面張力である。 [Preparation of fixing solutions [2] to [7] and [9] to [21]]
In the preparation of the fixing solution [1], fixing solutions [2] to [7] and [9] to [21] were prepared in the same manner except that the softener and diluent were changed to those shown in Table 3 below. did. In Table 3, softeners A-1 to A-5 and diluents B-1 to B-6 are compounds shown in Tables 1 and 2 below.
Moreover, softeners A-6 to A-16 are the compounds shown below.

Γ _A and γ _B (mN / m) are surface tensions at 20 ° C. of the softener and diluent, respectively.

[Preparation of Fixing Solution [8]]
A fixing solution [8] consisting of 100 parts by mass of ethyl 3-hydroxyhexanoate was prepared as a softening agent without using a diluent.

[Evaluation]
The heating fixing device of the image forming apparatus “bizhub C 253” (manufactured by Konica Minolta Business Technologies) is removed, the fixing device [1] shown below is mounted, and the above-mentioned dry developers [1] and [2] are fixed. Using the liquids [1] to [21] in the combinations shown in Table 3, a solid image was formed on the image support “J paper” (manufactured by Konica Minolta) with a toner adhesion amount of 4 g / m ² . The following evaluation was performed on the obtained solid image. The results are shown in Table 3 below. In this image formation, fixing was performed in an unheated state.
・ Fixer [1]
The fixing device [1] is provided with a fixing liquid supply means composed of a line-type ink jet nozzle as shown in FIG. 2 and a pressure applying means composed of a pressure roller.
The line-type ink jet constituting the fixing liquid supply means has a resolution of 600 dpi,
The droplet size is 10-15 pl.
The set supply amount of the fixer is 0.1 g / A4.
The pressure applied by the pressure applying means is 200 MPa.

<Stickness after standing over time>
The formed solid image part, the non-image part, and the solid image part are overlapped so as to overlap each other, and a weight is placed on the overlapped part so as to correspond to 80 g / cm ^2, and a constant temperature of 25 ° C. and a humidity of 30%. It was left for 30 minutes in a constant humidity bath. After being left, the degree of image loss of the two fixed images superimposed was graded in five stages from “G1” to “G5” shown below. In addition, G3 or more is a level which is satisfactory practically.
G1: Since the image portions are adhered to each other, the paper on which the image is fixed is peeled off, the image is severely lost, and the image is clearly transferred to the non-image portion.
G2: Since the images are bonded to each other, white spots of image defects are generated in some parts of the image portion.
G3: When separating two superimposed images, there is an image blur or gloss reduction on the fixing surface of each other, but there is almost no image loss and an acceptable level. Some transition is seen in the non-image area.
G4: When two superimposed images are released, a crisp sound is heard and a slight image shift is seen in the non-image area, but there is no image defect and there is no problem at all.
G5: No image loss or image transfer is seen in both the image portion and the non-image.

<Image loss>
The formed image was observed, and the degree of defect was evaluated according to the following three levels. Note that “Δ” or higher is a level that causes no practical problem.
○: There is no defect in the image portion, and the image is formed uniformly.
Δ: Gloss unevenness occurs on the image, but acceptable level.
X: An image cannot be formed uniformly, and fine white spots are formed in the image portion.

  From the results shown in Table 3, it can be seen that Examples 1 to 19 are superior to Comparative Examples 1 to 3 in terms of stickiness when left standing with time and image defects.

10 Image forming apparatus 20 Intermediate transfer members 21A, 21B, 21C Support rollers 30Y, 30M, 30C, 30K Image forming unit 31 Toner image carriers 31Y, 31M, 31C, 31K Photoconductors 32Y, 32M, 32C, 32K Charging means 33Y, 33M, 33C, 33K Exposure means 34Y, 34M, 34C, 34K Developing means 35Y, 35M, 35C, 35K Primary transfer means 36Y, 36M, 36C, 36K Cleaning means 40 Secondary transfer means 50, 50A, 50B, 50C, 50D Fixing Liquid supply means 51 Fixing liquid application roller 52 Pressure roller 53 Metering blade 54 Foam generator 55 Fixing liquid application roller 56 Pressure roller 57 Regulation blade 60 Cleaning means 70 Pressure applying means B Foam film F Fixing liquid M Liquid film T toner image P image support

Claims (4)

A fixing liquid for fixing a toner image composed of toner on an image support by softening the toner,
Contains at least a softener and a diluent,
The softener is a compound represented by the following general formula (1):
_A fixing solution characterized by satisfying the following formulas (2) and (3) when the surface tension at 20 ° C. of the softener and the diluent is γ _A and γ _B (mN / m), respectively.
Formula (1): R ¹ —COO—R ²
[In General Formula (1), R ¹ and R ² represent a linear or branched aliphatic hydrocarbon group, aryl group or heterocyclic group having 1 to 15 carbon atoms which may have a substituent, and R ¹ And at least one of R ² has a hydroxy group. ]
Formula (2): γ _B <γ _A
Formula (3): γ _B ≦ 30 The fixing solution according to claim 1, wherein a surface tension γ _B (mN / m) of the diluent satisfies the following formula (4).
Formula (4): 20 ≦ γ _B ≦ 30 An electrophotographic image forming method having at least an electrostatic latent image forming step, a developing step, a transfer step, and a fixing solution supplying step,
An electrophotographic image forming method using the fixing solution according to claim 1 or 2 as a fixing solution for softening toner in the fixing solution supply step.   4. The electrophotographic image forming method according to claim 3, wherein the toner comprises toner particles containing a polyester resin or a styrene acrylic resin as a binder resin.

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