JP5482813B2 - Fixing solution and 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 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 for softening 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 becomes longer and the fixing responsiveness is lowered (see Patent Documents 1 and 2). In addition, there is a problem that a noticeable residual liquid feeling (stickiness when the paper is touched by hand) occurs on the paper.
Further, for example, when an oil-in-water type in which an organic compound that is insoluble or hardly soluble in water is dispersed and mixed in water is used as the fixing solution, when a large amount of the fixing solution is supplied, an image such as paper The support absorbs the moisture of the fixing solution, and the image support is wrinkled and curled. 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 lowered (see Patent Document 3).
Regarding the fixing responsiveness, when the softening speed of the fixing liquid with respect to the toner is low, it is necessary to delay the image processing speed of the image forming apparatus, and there is a problem that the image processing ability inherent in the image forming apparatus cannot be exhibited. In particular, when performing image formation using color toner, the toner particles of different colors are overlapped to increase the thickness, and it is necessary to increase the softening speed of the fixing liquid with respect to the toner (see Patent Document 4). .

  As described above, the fixing solution used in the wet fixing method can increase the fixing speed and the drying speed while reducing the supply amount of the fixing liquid, and the stickiness in the formed image is reduced. In addition, excellent fixing properties such as high fixing strength are required.

Japanese Patent No. 43219105 Japanese Patent No. 4358896 Japanese Patent No. 3290513 JP 2011-128457 A

  The present invention has been made on the basis of the above-described circumstances, and it is possible to increase the fixing speed and the drying speed while reducing the supply amount of the fixing liquid, and to reduce the sticky feeling in the formed image. Another object of the present invention is to provide a fixing solution and an image forming method having high fixing strength.

The fixing liquid of the present invention is a fixing liquid that softens toner and fixes a toner image composed of the toner on an image support.
It contains an ester compound represented by the following general formula (1).

Formula (1): R ¹ — (CO) —O—R ²

[In General Formula (1), R ¹ represents a linear or branched alkyl group having 2 to 11 carbon atoms having at least one hydroxyl group, and R ² represents a linear or branched group having 1 to 4 carbon atoms. A branched alkyl group is shown. ]

In the fixing solution of the present invention, the ester compound represented by the general formula (1) preferably has a hydroxyl group at the β-position with respect to the carbonyl group in R ¹ in the general formula (1).

  In the fixing solution of the present invention, the ester compound represented by the general formula (1) is preferably ethyl 3-hydroxyhexanoate.

  The fixing solution of the present invention preferably further contains a diluent and a surfactant.

  In the fixing solution of the present invention, the ester compound represented by the general formula (1) is preferably contained in a proportion of 1 to 30% by mass with respect to the fixing solution.

The image forming method of the present invention includes an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image carrier,
A developing step of developing the electrostatic latent image with a dry developer containing toner to form a toner image;
A transfer step of transferring the toner image to an image support;
A fixing solution supplying step of supplying a fixing solution for softening the toner to the toner image transferred to the image support;
As the fixing solution, the above-described fixing solution is used.

  In the image forming method of the present invention, the toner is preferably composed of toner particles containing a polyester resin as a binder resin.

  According to the fixing solution of the present invention, since the ester compound represented by the general formula (1) (hereinafter also referred to as “specific ester compound”) is contained, the fixing speed is reduced while reducing the supply amount of the fixing solution. In addition, a high drying speed is realized, and a sticky feeling is reduced in the formed image, and a high fixing strength is obtained.

  Further, according to the image forming method of the present invention, in the wet fixing method, by using the fixing solution of the present invention, it is possible to increase the fixing speed and the drying speed while reducing the supply amount of the fixing liquid, An image having a high fixing strength can be formed while the sticky feeling is reduced in the formed image.

FIG. 3 is an explanatory cross-sectional view illustrating an example of a configuration of a fixing solution supply unit used when supplying the fixing solution of the present invention. FIG. 3 is an explanatory cross-sectional view illustrating an example of a configuration of a fixing solution supply unit and a pressure application unit used when supplying the fixing solution of the present invention. FIG. 6 is an explanatory cross-sectional view illustrating another example of the configuration of a fixing solution supply unit used when supplying the fixing solution of the present invention. FIG. 10 is an explanatory cross-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. FIG. 10 is an explanatory cross-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. 1 is a schematic diagram illustrating an example of a configuration of an image forming apparatus used in an image forming method of the present invention.

  Hereinafter, the present invention will be described in detail.

(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 on the image support, and contains a specific ester compound as a softening agent.
The fixing solution of the present invention contains a diluent such as water as an essential component, and may contain other components such as a dispersant as necessary.

[Ester Compound Represented by General Formula (1)]
The ester compound represented by the general formula (1) constituting the fixing solution of the present invention is a hydroxycarboxylic acid ester compound (hydroxyalkanoate), which is obtained by a dehydration condensation reaction between a carboxylic acid having a hydroxyl group and an alcohol. Is.
When the specific ester compound is contained in the fixing solution of the present invention, when the fixing solution is supplied to the toner image, the ester bond (group) in the molecule of the specific ester compound and the toner molecule are intermolecular. It is thought that the toner particles are softened by affinity through hydrogen bonding, and softening of the toner particles is promoted by intermolecular hydrogen bonding between the hydroxyl group and the toner molecule in the molecule of the specific ester compound. It is done. Further, it is considered that the softened toner particles are adsorbed to the paper fiber by intermolecular hydrogen bonding between the hydroxyl group in the molecule of the specific ester compound and the fiber cellulose of the image support such as paper, and high adhesiveness is obtained. It is done. That is, since these hydrogen bonds are considered to be effective for “softening of toner particles” and “affinity (adhesion) with paper”, the fixing solution of the present invention reduces the supply amount of the fixing solution. However, the fixing speed and the drying speed are increased, and the stickiness in the formed image is reduced and the fixing strength is high. The softening of the toner particles by the hydroxyl group is considered to be the same mechanism (solvation) as, for example, low-molecular alcohol or THF (tetrahydrofuran) dissolves the toner resin.

In general formula (1), R ¹ represents a linear or branched alkyl group having 2 to 11 carbon atoms and having at least one hydroxyl group. R ¹ preferably has 5 carbon atoms.
R ² represents a linear or branched alkyl group having 1 to 4 carbon atoms. R ² preferably has 2 carbon atoms.
Specific examples of the ester compound represented by the general formula (1) include ethyl lactate, isoamyl lactate, ethyl 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, ethyl 3-hydroxyoctanoate, 5-hydroxyoctane Examples include ethyl acid. These can be used individually by 1 type or in combination of 2 or more types.
In the present invention, the specific ester compound is preferably such that in R ¹ in the general formula (1), a hydroxyl group is located at the β-position with respect to the carbonyl group. Since the hydroxyl group is located at the β-position with respect to the carbonyl group, the carbonyl group and the hydroxyl group are likely to be located on the same side (same plane) in terms of molecular skeleton (stereoscopic). It is considered that a large number of hydrogen bond formations with the toner and fiber cellulose per molecule of the ester compound represented are secured. 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 hydroxyl group is located at the α-position, the carbonyl group and the hydroxyl 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. From the above, the structure in which the hydroxyl 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 specific ester compound is preferably contained in a proportion of 1 to 30% by mass, more preferably 5 to 20% by mass with respect to the fixing solution.
When the content of the specific ester compound is within the above range, high affinity for the binder resin contained in the toner particles is obtained, high fixing strength and fixing speed are obtained, and stickiness after fixing. Is suppressed.
When the content of the specific ester compound is less than 1% by mass, high affinity for the binder resin contained in the toner particles cannot be obtained, and the fixing strength and fixing speed may be reduced. On the other hand, when the content ratio of the specific ester compound exceeds 30% by mass, the sticky feeling after fixing remains, which may adversely affect the drying speed and the sticky feeling.

[Diluent]
The fixing solution of the present invention contains a diluent that dilutes and disperses a specific ester compound. Examples of the diluent include water, specifically ion exchange water. A solvent capable of dissolving a specific ester compound, specifically, isoparaffin, silicone oil, or the like can also be used.
The diluent is preferably contained in a proportion of 50 to 90% by mass with respect to the fixing solution, and more preferably 80 to 90% by mass.

[Dispersant]
In the fixing solution of the present invention, a dispersant may be contained as needed to improve the solubility or dispersibility of a specific ester compound in a diluent.
Examples of the dispersant include surfactants, specifically, anionic surfactants, cationic surfactants, nonionic surfactants, and the like.
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 Acid sulfos, alkylsulfosuccinic acid ester salts such as sodium polyoxyethylene lauryl sulfosuccinate, and And the like of 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 in a proportion of 0 to 10% by mass, more preferably 1 to 5% by mass with respect to the fixing solution.

[Fixing solution supply amount]
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.

[Fixing solution production method]
As a method for producing the fixing solution of the present invention, for example, a specific ester compound and a dispersant as necessary are sequentially added to a tank for supplying a fixing solution, and then a diluent is added and an ultrasonic homogenizer is used. And stirring for 5 minutes. Thereby, it is possible to prepare a fixing solution having a dispersed particle diameter of a specific ester compound of 150 to 250 μm.

[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 means include an inkjet nozzle, a sprayer using an ultrasonic vibrator, a sprayer using compressed air, a sprayer that electrostatically drops liquid droplets, and 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 0.5-50pl.
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 whose surface has releasability can be used. The applied pressure is not particularly limited, but is preferably 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 liquid supply unit 50B includes a fixing liquid application roller 51 and a pressure roller 52 provided to face the fixing liquid 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 where 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, 1-100 micrometers is preferable.
Further, the pressing force of the pressure roller 52 is preferably 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 the form of foam, 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 in which the tip portion is separated from the surface of the fixing liquid application roller 55.
In such a fixing solution supply means 50C, the supply amount of the fixing solution F is controlled by the rotation of the fixing solution application roller 55 and the pressure roller 56, and the supply amount of the foam-like fixing solution F on the fixing solution application roller 55 is regulated. It is regulated by the blade 57 and supplied as a foam film B to the entire surface of the image support P to which the toner image T has been transferred, 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, 50-80 micrometers is preferable.
Further, the pressing force of the pressure roller 56 is preferably 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 specific ester compound, so that the fixing rate and the drying rate can be increased while reducing the supply amount of the fixing solution, and in the formed image. The sticky feeling is reduced and high fixing strength is obtained.

(Image forming method)
The 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 dry process including a toner containing at least a binder resin. A developing step of developing with a developer to form a toner image, a transferring step of transferring the toner image to the image support, and a fixing solution for supplying a fixing solution for softening the toner to the toner image transferred to the image support A fixing step of using the fixing solution of the present invention as a 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 is not particularly limited, and examples thereof include an inorganic photoreceptor such as amorphous silicon and selenium, or a drum-like one made of an organic photoreceptor such as polysilane and phthalopolymethine.
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 agitated, and the toner is charged by friction at that time, and is held on the surface of the rotating magnet roller to form 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 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. An additive may be externally added.

The toner used in the image forming method of the present invention preferably has a particle size of 3.5 to 7.0 μm, more preferably 5.0 to 6.5 μm as a volume-based median diameter.
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.
When the volume-based median diameter of the toner is less than 3.5 μm, the formed image may become sticky. On the other hand, when the volume-based median diameter of the toner exceeds 7.0 μm, the specific surface area of the toner is small, and the contact area with the fixing liquid is not sufficiently ensured in the fixing liquid supply process described later, and the toner image is not captured. There is a risk that it cannot be reliably fixed to the image support.

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 measurement apparatus, the measurement particle count is 25000, the aperture diameter is 50 μm, the frequency value is calculated by dividing the measurement range of 1 to 30 μm into 256, and the volume integrated fraction is 50 % Particle size is the volume-based median diameter.

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

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 image forming method of the present invention preferably has a glass transition point of 30 to 70 ° C., more preferably 35 to 50 ° C., from the viewpoints of heat storage stability and blocking resistance.

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 image forming method of the present invention preferably has a softening point of 90 to 120 ° C., more preferably 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” ( (Shimadzu Corporation) pressurizes with a force of 3820 kg / cm ² for 30 seconds to make a cylindrical molded sample with a diameter of 1 cm. Then, the molded sample is subjected to an environment of temperature 24 ± 5 ° C. and humidity 50 ± 20% RH. Below, with a flow tester “CFT-500D” (manufactured by Shimadzu Corporation), a cylindrical die hole (with a load of 196 N (20 kgf), a starting temperature of 60 ° C., a preheating time of 300 seconds and a heating rate of 6 ° C./min) 1 mm diameter x 1 mm) from the end of preheating using a 1 cm diameter piston, offset temperature T _off measured with a melt temperature measurement method of the temperature rising method with an offset value of 5 mm Measured with _set 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, a 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 carboxyl 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, neopentyl A binder resin having a crosslinked structure can also be obtained using a polyfunctional vinyl such as 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 of 120 to 250 ° C. in an inert gas atmosphere. In the condensation polymerization, a known esterification catalyst may be used as necessary.

  The proportion of the dissociated acid monomer in the binder resin is preferably 0 to 20% when using a styrene- (meth) acrylic resin, more preferably 5 to 15%, and 10 when using a polyester resin. It is preferable that it is -50%, More preferably, it is 20-50%.

The binder resin preferably has a glass transition point of 30 to 70 ° C, more preferably 35 to 45 ° C.
When the glass transition point of the binder resin is less than 30 ° C., the heat resistant storage property may not be 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.

The binder resin preferably has a weight average molecular weight of 3,000 to 100,000, more preferably 5,000 to 50,000.
When the weight average molecular weight of the binder resin is less than 3,000, the strength of the toner particles is reduced, which causes toner scattering. On the other hand, when the weight average molecular weight of the binder resin exceeds 100,000, there is a possibility that high fixing strength cannot be obtained in the formed image.

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 was flowed at a flow rate of 0.2 mL / min, and the sample (binder resin) was dissolved in THF to a concentration of 1 mg / mL under a dissolution condition in which treatment was performed for 5 minutes using an ultrasonic disperser at room temperature. A sample solution is obtained by processing with a 2 μm membrane filter, and 10 μL of this sample solution is injected into the apparatus together with the carrier solvent described above, detected using a refractive index detector (RI detector), and the molecular weight distribution of the sample Is calculated using a calibration curve measured using 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, and 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, 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, 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, C.I. I. And CI Pigment Green 7.
These colorants can be used alone or in combination of two or more.

  It is preferable that the content rate of a coloring agent is 1-10 mass parts with respect to 100 mass parts of binder resin, More preferably, it is 2-9 mass parts.

(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 is 0-10 mass parts with respect to 100 mass parts of binder resin, More preferably, it is 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 10 to 500 parts by mass, more preferably 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 0.1 to 10 parts by mass, more preferably 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., external additives such as so-called fluidizing agents and cleaning aids are added to the toner particles. It can be used in a state where is 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 and the like.
These inorganic fine particles are preferably subjected to a surface treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil or the like in order to improve the dispersibility of the toner particles on the surface and the environmental stability. .
Examples of the cleaning aid include polystyrene fine particles and 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 0.05 to 5 parts by mass, more preferably 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, and a dissolution suspension method.

(Dry developer)
The developer used in the image forming method of the present invention is a dry-type developer, and is a two-component developer in which a toner and a carrier are mixed even if it is a one-component developer composed only of magnetic or non-magnetic toner. It may be.
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 of 15 to 100 μm, more preferably 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, a transfer roller, or the like 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. And 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 image forming method of the present invention can be executed by, for example, the following image forming apparatus.
FIG. 6 is a schematic diagram showing an example of the configuration of an image forming apparatus used in the 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 member 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 image forming method of the present invention, in the wet fixing method, by using the fixing solution of the present invention, the fixing rate and the drying rate can be increased and formed while reducing the supply amount of the fixing solution. It is possible to form an image having reduced stickiness and high fixing strength.

[Toner Preparation Example 1]
(1) Preparation of binder resin particle dispersion C ₁₀ H ₂₁ (OCH ₂ CH ₂ ) ₂ SO ₃ Na anionic surfactant in a reaction vessel equipped with a stirrer, temperature sensor, cooling tube and nitrogen introducing device 4 parts by mass was added together with 3040 parts by mass of ion-exchanged water to prepare an aqueous surfactant solution. 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., 532 parts by mass of styrene, n- A monomer solution consisting of 200 parts by mass of butyl acrylate, 68 parts by mass of methacrylic acid and 16.4 parts by mass of n-octyl mercaptan was dropped into the reaction vessel over 1 hour. After the dropping, polymerization was performed by heating and stirring at 75 ° C. for 2 hours to prepare a binder resin particle dispersion [1] in which the binder resin particles were dispersed. The produced binder resin particles had a glass transition point of 40 ° C. and a weight average molecular weight of 35,000. Further, the ratio of the dissociated acid monomer in the binder resin particles was 5%.

(2) Preparation of Colorant Particle Dispersion Solution 7 parts by mass of “Dowfax 2A-1” (manufactured by Dow Chemical Co., Ltd.) was added to 160 parts by mass of ion-exchanged water, and dissolved and stirred to prepare a surfactant aqueous solution. 20 parts by mass of carbon black was gradually added to this aqueous surfactant solution, and dispersion treatment was performed using “SC Mill” (manufactured by Mitsubishi Mining Co., Ltd.) to prepare a colorant particle dispersion [1]. The colorant particles were measured using “MICROTRAC UPA-150” (manufactured by HONEYWELL), and the particle size was 200 nm in terms of volume-based median diameter.

(3) Preparation of toner particles In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device, 420.7 parts by mass of binder resin particle dispersion [1] (solid content conversion), ion-exchanged water 900 Part by mass and 200 parts by mass of the colorant particle dispersion [1] were added and stirred.
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 raised after standing for 3 minutes, and the temperature of the system was raised 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 21 μm, 40.2 parts by mass of sodium chloride was ionized. An aqueous solution dissolved in 1000 parts by mass of exchange water was added to stop the association.
Thereafter, the liquid temperature was set to 70 ° C. as an aging treatment, and the fusion was continued by heating and stirring for 1 hour. At this time, the average circularity of the particles was 0.940. Further, the mixture was cooled to 30 ° C. at a rate of 8 ° C./min, filtered, washed repeatedly with ion exchange water at 45 ° C., and then dried with hot air at 40 ° C. to obtain toner particles [1]. . The particle diameter of the toner particles [1] was 6.2 μm in terms of volume-based median diameter.
100 parts by mass of the toner particles [1] were treated with 0.6 mass of hexamethylsilazane-treated silica (average primary particle size 12 nm) and n-octylsilane using “Henschel mixer” (manufactured by Mitsui Miike Mining Co., Ltd.). Toner [1] was prepared by adding 0.8 part by mass of titanium dioxide (average primary particle size: 24 nm).

[Toner Preparation Example 2]
Toner [2] was prepared in the same manner as in Toner Preparation Example 1, except that the amount of methacrylic acid added in the preparation of the binder resin particle dispersion was changed to 120 parts by mass. The produced binder resin particles had a glass transition point of 42 ° C. and a weight average molecular weight of 30,000. Further, the ratio of the dissociated acid monomer in the produced binder resin particles was 15%.

[Toner Preparation Example 3]
Into a flask equipped with a stirrer, a nitrogen inlet tube, a temperature controller and a rectifying column, the following polyvalent carboxylic acid and polyhydric alcohol were charged, and this reaction solution was heated to 190 ° C. over 1 hour, Was confirmed to be uniformly stirred, and then catalyst Ti (OBu) ₄ (0.003% by mass with respect to the total amount of the carboxylic acid component of the polyester resin) was added.
(Polyvalent carboxylic acid)
Terephthalic acid: 30 parts by mass Isophthalic acid: 3 parts by mass Adipic acid: 3 parts by mass (polyhydric alcohol)
2,2-bis (4-hydroxyphenyl) propanepropylene oxide 2-mole adduct: 75 parts by mass 2,2-bis (4-hydroxyphenyl) propaneethylene oxide 2-mole adduct: 25 parts by mass It took 6 hours from the same temperature while distilling, the temperature was raised to 240 ° C., and the dehydration condensation reaction was continued at 240 ° C. for further 6 hours to carry out polymerization to obtain a polyester resin [1]. This polyester resin [1] had a glass transition point of 40 ° C. and a weight average molecular weight of 40,000. Moreover, the ratio of the dissociated acid monomer of the polyester resin [1] was 26%.
And 400 mass parts of polyester resin [1] was thrown into 1700 mass parts of ethyl acetate, and it heated up to 70 degreeC, melt | dissolved, and mixed, and obtained resin solution [1].
Separately, 2000 parts by mass of ion-exchanged water and 4.8 parts by mass of sodium dodecyl sulfate were stirred and dispersed to prepare an aqueous phase serving as a continuous phase. Into this aqueous phase, the resin solution [1] was added while stirring with a “TK homomixer Mark II 2.5 type” (manufactured by PRIMIX Corporation), and oil droplets were prepared by adjusting the stirring rotation speed. Thereafter, the mixture was distilled off under reduced pressure at 50 ° C. to remove ethyl acetate to obtain a binder resin particle dispersion [3] having a solid content of 20 parts by mass. The volume-based median diameter of the binder resin particles was 180 nm.
Binder resin particle dispersion [3] 272 parts by mass (in terms of solid content), 2200 parts by mass of ion-exchanged water, and 98 parts by mass of colorant particle dispersion were provided with a thermometer, a cooling tube, a nitrogen introducing device, and a stirring device. It put into a separable flask. Furthermore, the pH in which the aqueous sodium hydroxide solution (25% by mass) was added was adjusted to 10 while maintaining the temperature in the system at 30 ° C.
Next, an aqueous solution in which 54.3 parts by mass of magnesium chloride hexahydrate is dissolved in 54.3 parts by mass of ion-exchanged water is added, and then the temperature inside the system is raised to 60 ° C. to bind. The aggregation reaction between the resin particles and the colorant particles was started.
After starting the agglutination reaction, sampling is performed periodically, and using a particle size distribution measuring apparatus “Coulter Multisizer 3” (manufactured by Beckman Coulter, Inc.), the median diameter (D50) of the particles based on volume is 6.0 μm. At that time, 20.1 parts by mass of ethylenediaminetetraacetic acid was added. At this time, the circularity of the particles was 0.92.
The temperature was raised, and when the circularity of the particles reached 0.96, the suspension was cooled to 10 ° C. at 6 ° C./min to obtain a toner particle dispersion.
Next, the produced toner particle dispersion was subjected to solid-liquid separation with a basket-type centrifuge “MARK III type” (model number 60 × 40) (manufactured by Matsumoto Kikai Kogyo Co., Ltd.) to form a toner wet cake. Thereafter, the toner washing and solid-liquid separation were repeated until the electric conductivity of the filtrate reached 15 μS / cm or less.
Subsequently, the wet cake was transferred to an airflow dryer “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.), and dried until the water content reached 0.5% by mass. The drying process was performed by blowing an air current of 40 ° C. and 20% RH. The dried toner particles were allowed to cool to 24 ° C., and 1 part by mass of hydrophobic silica (average primary particle size: 14 nm) was mixed with a Henschel mixer with respect to 100 parts by mass of the toner. 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 produce toner [3].

[Toner Preparation Example 4]
In the same manner as in Preparation Example 3 of the toner, except that the addition amount of terephthalic acid was 55 parts by mass, the addition amount of isophthalic acid was 4 parts by mass, and 41 parts by mass of fumaric acid instead of adipic acid, the toner [4 ] Was produced. The produced polyester resin had a glass transition point of 45 ° C. and a weight average molecular weight of 33,000. Moreover, the ratio of the dissociated acid monomer of the produced polyester resin was 50%.

<Preparation Examples 1-4 of Dry Developer>
Each of toners [1] to [4] is mixed with a silicone carrier coated ferrite carrier having a volume average particle diameter of 60 nm to produce dry developers [1] to [4] having a toner concentration of 6% by mass. did.

<Preparation Example 1 of Fixing Solution>
2 parts by mass of the softening agent [1] shown in Table 1, 1 part by mass of sorbitan monolaurate, and 97 parts by mass of ion-exchanged water were stirred for 5 minutes with an ultrasonic homogenizer to prepare a fixing solution [1].

<Preparation Examples 2-14 of Fixing Solution>
Fixing solutions [2] to [14] were prepared in the same manner except that the softening agent [1] was changed to that shown in Table 1 in Preparation Example 1 of the fixing solution.

<Examples 1 to 26, Comparative Examples 1 to 4>
The image forming apparatus “bizhub C 253” (manufactured by Konica Minolta Business Technologies Co., Ltd.) is removed and the fixing device [1] shown below is mounted, and the types of dry developer and fixing solution shown in Table 2 are combined. Then, 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 2. In this image formation, fixing was performed in an unheated state.
・ Fixer [1]
The fixing device [1] is composed of a fixing liquid supply means comprising a line type ink jet nozzle as shown in FIG.
The line-type ink jet constituting the fixing liquid supply means has a resolution of 600 dpi and a droplet size of 10 to 15 pl.
The set supply amount of the fixer is 0.4 g / A4.

<Evaluation of stickiness after standing over time>
The formed solid image part, the non-image part, and the solid image part are overlapped face to face 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 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, image loss is severe, and clear image transfer to the non-image portion is observed.
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 the two superimposed images, image blurring or gloss reduction occurs on the fixing surfaces of each other, but the image level is acceptable with almost no image loss. Some transition is seen in the non-image area.
G4: When the two overlapped images are separated, a crisp sound is heard, and a slight image shift is observed in the non-image part, but there is no image loss and there is no problem at all. G5: Both the image part and the non-image are completely absent. There is no image loss or image transfer.

<Abrasion fixing rate>
Five seconds after fixing, the surface of the solid image was rubbed with a 1 cmφ cotton cloth, and the reflection density before and after rubbing was measured by “RD-918” (manufactured by Macbeth). The rubbing and fixing rate was calculated by the following formula (1) and evaluated according to the following evaluation criteria. It should be noted that if the rubbing and fixing rate is 70% or more, there is no practical problem.
Formula (1): Scratch fixing rate (%) = {reflection density after rubbing / reflection density before rubbing (1.40)} × 100

<Change in the amount of fixing solution with respect to fixing strength>
The rubbing and fixing rate when the initial set supply amount 0.4 g / A4 of the fixing solution is less than 25%, 25 to 50%, 50 to 75%, and 100% is described above. It calculated | required on the conditions similar to Formula (1). The amount of the fixing solution when the rubbing fixing rate was 80% was evaluated according to the following evaluation criteria. The rank “C” or higher is regarded as a pass level.
A (excellent): amount of fixing solution less than 25% B (good): amount of fixing solution of 25% to less than 50% C (practical): amount of fixing solution of 50% to less than 75% D (failed): fixing 75% or more of liquid

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 Regulator blade 60 Cleaning means 70 Pressure applying means B Foam film F Fixing liquid M Liquid film T toner image P image support

Claims (7)

In a fixing solution for fixing a toner image composed of the toner on an image support by softening the toner,
A fixing solution comprising an ester compound represented by the following general formula (1):
Formula (1): R ¹ — (CO) —O—R ²
[In General Formula (1), R ¹ represents a linear or branched alkyl group having 2 to 11 carbon atoms having at least one hydroxyl group, and R ² represents a linear or branched group having 1 to 4 carbon atoms. A branched alkyl group is shown. ] The fixing according to claim 1, wherein the ester compound represented by the general formula (1) has a hydroxyl group at the β-position with respect to the carbonyl group in R ¹ of the general formula (1). liquid.   The fixing solution according to claim 2, wherein the ester compound represented by the general formula (1) is ethyl 3-hydroxyhexanoate.   The fixing solution according to claim 1, further comprising a diluent and a surfactant.   The fixing solution according to any one of claims 1 to 4, wherein the ester compound represented by the general formula (1) is contained in a proportion of 1 to 30% by mass with respect to the fixing solution. An electrostatic latent image forming step of forming an electrostatic latent image on the electrostatic latent image carrier;
A developing step of developing the electrostatic latent image with a dry developer containing toner to form a toner image;
A transfer step of transferring the toner image to an image support;
A fixing solution supplying step of supplying a fixing solution for softening the toner to the toner image transferred to the image support;
An image forming method using the fixing solution according to claim 1 as the fixing solution.   The image forming method according to claim 6, wherein the toner comprises toner particles containing a polyester resin as a binder resin.