JP2009169135A - Image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method which employs a fixing device of a free nip belt system, and suppresses the occurrence of an electrostatic offset phenomenon even when the device is used for a long period of time to form a high-quality image high in resolution and free from image defects. <P>SOLUTION: The image forming method includes fixing a toner image of a toner containing fine particles of an external additive, in a fixing device that includes a heating roller, an endless fixing belt pressed to be in contact with the heating roller, and a press-contact mechanism composed of a press-contact member inside the belt and in a form along the outer form of the heating roller in an active state, and an end part press-contact member disposed in a downstream side of the press-contact member and imparting a release force to the heating roller. The fine particles of the external additive comprise a compound oxide containing silicon atoms and titanium atoms and/or aluminum atoms, in which an abundance ratio of silicon atoms in the surface layer of the particle is higher than an abundance ratio of silicon atoms in the whole particle. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming method using electrophotography.

In recent years, in electrophotographic image forming methods, the range of use has expanded from the act of simple copying to the field of light printing, particularly with the evolution of networks that can easily transmit digital data. In this light printing field, unlike conventional office copying, high print quality is required to add value to the printed matter, and various types of image support can be used, from thick paper to thin paper. Is desired.
However, in an electrophotographic image forming method, a method of fixing toner by using heat at the time of fixing is generally used, and in particular, a contact heating method is most preferably used in order to increase thermal efficiency from the viewpoint of energy saving. However, in this contact heating method, the image support comes into contact with the heating roller, so the adhesion to the fixing member and heat transfer differ depending on the type of image support. For example, in the case of thin paper, the winding around the heating roller occurs. In the case of thick paper, there is a problem that the heat energy for fixing is consumed for heating the paper, the toner is not sufficiently melted, and sufficient fixability cannot be obtained.

In order to solve such a problem, as a fixing device, a nip portion is constituted by a heating roller and a pressure fixing belt, and the width of the nip portion is controlled, so that it is sufficient regardless of the type of the image support. A so-called free nip belt type has been proposed (see, for example, Patent Documents 1 to 3).
In such a fixing device, the pressure of the fixing belt toward the heating roller can be changed depending on the position in the nip portion, and the pressure is increased near the outlet of the nip portion to be peeled off from the heating roller. By applying force, it is possible to make it easy to peel off the heating roller even if it is thin paper at the exit of the nip, and as a result, wrapping of the image support around the heating roller near the exit of the nip is suppressed. There is also an advantage that can be done.

  However, this free nip belt type fixing device has a problem that, when used for a long period of time, toner and toner constituents are accumulated on the heating roller, and so-called electrostatic offset phenomenon occurs.

JP 2006-267860 A JP 09-329980 A Japanese Patent Laid-Open No. 06-214479

  The present invention has been made on the basis of the above-described circumstances, and its object is to provide an electrostatic image forming method that employs a specific free nip belt type fixing device even when used for a long period of time. An object of the present invention is to provide an image forming method in which the occurrence of an offset phenomenon is suppressed, and as a result, a high-quality image having high resolution and no image defects can be formed.

  As a result of detailed analysis of the situation of the fixing device by the present inventors, in the fixing device in which a peeling force is applied near the exit of the nip portion and the peelability of the image support from the heating roller is improved, the image on the fixing belt side As a result of the structure in which the support is pulled and a force acts in the direction of peeling from the heating roller, the image support is rapidly peeled off from the heating roller. As a result, peeling charging occurs. It was estimated that the electrostatic offset phenomenon occurred due to the accumulation of. More specifically, it was estimated that the toner and the toner constituent components are transferred to the heating roller side due to the influence of the charge due to the peeling charging.

  In order to solve this problem, the present inventors have intensively studied. As a result, when the external additive fine particles to be used are overly charged because they are made of a relatively insulating material such as silica, the toner component As a result, the present invention has been completed.

In the image forming method of the present invention, a toner image formed by developing an electrostatic latent image formed on an electrostatic latent image carrier with a toner containing at least colored particles and external additive fine particles, In an image forming method of transferring to an image support and fixing in a fixing device,
The fixing device includes a heating roller, an endless fixing belt press-contacted to the heating roller, a press-contact member configured to conform to the outer shape of the heating roller in an operating state inside the fixing belt, and the press-contact member And a pressure contact mechanism composed of an end pressure contact member that is disposed on the downstream side of the heating roller and applies a peeling force to the heating roller.
The external additive fine particles are composed of a composite oxide containing silicon atoms and titanium atoms and / or aluminum atoms, and the abundance ratio of silicon atoms in the surface layer is greater than the abundance ratio of silicon atoms in the whole. It is also characterized by high.
Here, the composite oxide represents an oxide containing two or more kinds of metal atoms.

In the image forming method of the present invention, the external additive fine particles, when the abundance ratio of silicon in the entire atom R _1, the existence ratio of silicon atoms in the surface layer and the R _2, coefficients (R ₁₎ / (R ₂ ) is preferably 0.7 or less.

In the image forming method of the present invention, the external additive fine particles preferably have a total content mass of titanium atoms and aluminum atoms larger than the content mass of silicon atoms.
The external additive fine particles preferably have a number average primary particle diameter of 20 to 200 nm.

According to the image forming method of the present invention, the toner contains the specific external additive fine particles, and the specific external additive fine particles have an abundance ratio of silicon atoms in the surface layer of the total presence of silicon atoms. Higher than the ratio, and the toner does not migrate to the heating roller due to peeling charging near the exit of the nip portion of the fixing device. Is suppressed, and the occurrence of the electrostatic offset phenomenon can be suppressed.
The reason why the specific external additive fine particles contained in the toner can suppress the occurrence of electrostatic offset phenomenon by suppressing excessive charging while having sufficient chargeability is presumed as follows.
That is, silica, which is an oxide of silicon atoms, has a structure that is easily charged and easily retains charges, but charges are accumulated due to the structure that easily retains charges.
On the other hand, since oxides of titanium atoms and aluminum atoms have relatively low resistance, charges can be leaked, but it is difficult to retain the charges.
The specific external additive fine particles used in the present invention have a sufficient charge-imparting ability for the colored particles because the surface layer has a large number of oxides having silicon atoms (hereinafter referred to as “silica component”) oriented. And a structure in which a relatively low resistance component such as an oxide having a titanium atom and / or an aluminum atom (hereinafter referred to as “titania and / or alumina component”) is oriented. Therefore, excessive charge generated by the silica component in the surface layer can be suppressed by leaking inside the external additive fine particles by the titania and / or alumina component present inside. It is guessed.

  The electrostatic offset phenomenon can be suppressed by using, for example, fine particles having a relatively low resistance due to a metal oxide such as titanium oxide or aluminum oxide as the external additive fine particles, but charging to the colored particles constituting the toner can be suppressed. Good chargeability and fluidity cannot be obtained, for example, the imparting ability varies depending on environmental fluctuations.

  Hereinafter, the present invention will be described in detail.

(Image forming method)
In the image forming method of the present invention, a toner image formed by developing an electrostatic latent image formed on an electrostatic latent image carrier with a toner containing at least colored particles and external additive fine particles, In the image forming method of transferring to an image support and fixing in a fixing device, the fixing device includes a heating roller, an endless fixing belt pressed against the heating roller, and an operating state inside the fixing belt. A pressure contact member having a shape that conforms to the outer shape of the heating roller, and a pressure contact mechanism that is disposed downstream of the pressure contact member and includes an end pressure contact member that applies a peeling force to the heat roller. The fine particles are composed of a composite oxide containing silicon atoms and titanium atoms and / or aluminum atoms, and the silicon atoms are present in the surface layer. , It is higher than the abundance ratio of silicon atoms in its entirety.
Hereinafter, such external additive fine particles are also referred to as “specific external additive fine particles”.
Since the specific external additive fine particles are those in which silicon atoms are surface-oriented, the toner obtained by externally adding the colored particles to the colored particles does not cause a packing phenomenon or the like even when stored still, It exhibits excellent flow characteristics similar to that of a toner externally treated with silica.

[Specific external additive fine particles]
In specific external additive fine particles, “the presence ratio of silicon atoms in the surface layer is higher than the existence ratio of silicon atoms in the whole” means that more silicon atoms are present on the surface. Specifically, the coefficient (R ₁ ) / (R ₂ ) is less than ₁ when the abundance ratio of silicon atoms in the whole is R ₁ and the abundance ratio of silicon atoms in the surface layer is R _2. Say.
The coefficient (R ₁ ) / (R ₂ ) of the silicon atom is preferably 0.7 or less, more preferably 0.5 or less, and particularly preferably 0.25 or less.

The abundance ratio R ₁ of silicon atoms in the whole specific external additive fine particles is determined by the XRF (XRF) apparatus “XRF-1800” (Shimadzu Corporation) for the contained mass of silicon atoms, titanium atoms and / or aluminum atoms in the whole. ) And calculated as a mass fraction.
Specifically, the following steps (1) to (3) are performed.
(1) First, as a sample for preparing a calibration curve, a known amount of silicon dioxide is added to 100 parts by mass of styrene powder to produce a pellet for measuring silicon atoms. Similarly, a known amount of oxidation is added to 100 parts by mass of styrene powder. A titanium atom measurement pellet to which titanium is added and / or an aluminum atom measurement pellet in which a known amount of aluminum oxide is added to 100 parts by mass of styrene powder is prepared.
(2) Next, each of the produced silicon atom measurement pellets, titanium atom measurement pellets and / or aluminum atom measurement pellets was subjected to X-ray fluorescence analysis, and each silicon pellet, titanium oxide or aluminum oxide in styrene powder was analyzed. A calibration curve is created based on the peak intensity obtained from
(3) Thereafter, the sample of the specific external additive fine particles is subjected to fluorescent X-ray analysis, and the obtained peak intensity is collated with a calibration curve, whereby the content of silicon atoms, titanium atoms and / or aluminum atoms is quantified. The
In this measurement, the Kα peak angle of the element to be measured was determined from the 2θ table and used. The X-ray generation part conditions are target: Rh, tube voltage: 40 kV, tube current: 95 mA, filter: none, and spectroscopic system conditions are slit: standard, attenuator: none, spectral crystal: (Si = PET, Ti = LiF, Al = PET), detector: (Si = FPC, Ti = SC, Al = FPC).

On the other hand, the abundance ratio R ₂ of silicon atoms in the surface layer of the specific external additive fine particles is determined by the inclusion of silicon atoms, titanium atoms and aluminum atoms in the surface layer from the surface to a depth of several nanometers (about 10 atomic layers). The mass is measured by an X-ray photoelectron spectrometer “ESCA-1000” (manufactured by Shimadzu Corporation), and is calculated as a mass fraction.
Specifically, calibration curves were created for silicon atoms, titanium atoms, and aluminum atoms in the same manner as in (1) and (2) of the measurement using the X-ray fluorescence (XRF) apparatus, and the following measurement conditions were used. Samples of specific external additive fine particles were measured by X-ray photoelectron spectroscopy.
-Measurement conditions-
X-ray intensity: 30 mA, 10 kV
Analytical depth; Normal mode Quantitative element; Si, Ti and Al elements simultaneously quantitatively analyzed

In the specific external additive fine particles, the abundance ratio of silicon atoms in the whole is preferably 1 to 49%, more preferably 1 to 20%.
Moreover, in the specific external additive fine particles, the abundance ratio of silicon atoms in the surface layer from the surface to a depth of several nanometers is preferably 70 to 100%, more preferably 80 to 100%.
If the abundance ratio of silicon atoms in the whole external additive fine particles is less than 1%, the resulting external additive fine particles may not have sufficient chargeability, or toner obtained by external addition treatment to colored particles On the other hand, if the existing ratio of silicon atoms in the entire external additive fine particles exceeds 49%, the resulting external additive fine particles may not be able to sufficiently suppress overcharge. is there. Moreover, when the abundance ratio of silicon atoms in the surface layer is less than 70%, the charge imparting ability to the colored particles may be low.

[Average particle diameter of external additive fine particles]
The specific external additive fine particles preferably have a number average primary particle size of 10 to 500 nm, more preferably 20 to 300 nm, and particularly preferably 20 to 200 nm.
When the number average primary particle diameter is in the above range, the charge on the surface of the colored particles can be stabilized, and the specific external additive fine particles themselves can be held on the surface of the colored particles with high stability.

The number average primary particle size of the specific external additive fine particles is measured using a scanning electron microscope (SEM).
Specifically, an SEM photograph magnified 30,000 times is captured by a scanner, and external additive fine particles present on the toner surface of the SEM photograph image are analyzed by an image processing analyzer “LUZEX AP” (manufactured by Nireco). Binarization is performed, and the horizontal ferret diameter is calculated for 100 external additive fine particles, and the average value is taken as the number average primary particle diameter.
When the number average primary particle diameter of the external additive fine particles is small and exists as an aggregate on the toner surface, the particle diameter of the primary particles forming the aggregate is measured.

[Specific surface area of external additive fine particles]
The specific external additive fine particles preferably have a BET specific surface area of ² to 100 m ² / g.
Note that the BET specific surface area is a specific surface area calculated by using a BET adsorption isotherm from an adsorption amount of gas molecules having a known adsorption occupation area such as nitrogen gas.
When the BET specific surface area of the external additive fine particles is within the above range, the external additive fine particles can stably act as an external additive without being excessively embedded in the colored particles or detached from the surface of the colored particles. An environment is formed.

The BET specific surface area of the specific external additive fine particles is a value measured by a multipoint method (7-point method) using an automatic specific surface area measuring device “GEMINI 2360” (manufactured by Shimadzu Micromeritics).
Specifically, first, 2 g of the external additive fine particles are filled into a straight sample cell, and the inside of the cell is replaced with nitrogen gas (purity 99.999%) for 2 hours as a pretreatment, and then the external additive is added by the measuring apparatus main body. It is calculated by adsorbing and desorbing nitrogen gas (purity 99.999%) on the fine particles.

[Bulk density of external additive fine particles]
The specific external additive fine particles preferably have a bulk density of 100 to 400 g / L.
The bulk density is a value obtained by dividing the mass of the filled external additive fine particles by the volume when the external additive fine particles are filled in a container having a known volume. This means the degree of existence of voids formed between the external additive fine particles per unit volume when the agent fine particles are filled.
When the bulk density of the specific external additive fine particles is within the above range, the obtained toner ensures a space between the toner particles, so that packing due to stationary storage is unlikely to occur. Sufficient fluidity can be reliably maintained.

The bulk density of the specific external additive fine particles is a value measured by a Kawakita-type bulk density measuring device “IH-2000 type” (manufactured by Seishin Enterprise Co., Ltd.).
Specifically, a sample (specific external additive fine particles) is placed on a 120-mesh sieve, the sieve is vibrated for 90 seconds at a vibration strength of 6, and the sample is dropped into a container with a known volume. After stopping and allowing to stand for 30 seconds, the container is ground and the mass is measured to calculate the bulk density.

[Hydrophobicity of external additive fine particles]
The specific external additive fine particles preferably have a hydrophobicity of 30% or more.
When the degree of hydrophobicity of the specific external additive fine particles is 30% or more, there is an advantage that sufficient chargeability can be obtained even in a high temperature and high humidity environment.

The degree of hydrophobicity of specific external additive fine particles is a value measured as follows.
That is, 50 mL of water is put into a 200 mL beaker, and 0.2 g of external additive fine particles (sample) are added, and methanol is added from a burette whose tip is immersed in water at the time of dropping while stirring with a magnetic stirrer. From the amount (Me) of methanol dropped when the external additive fine particles (sample) that initially floated completely settled, calculation is performed using the following formula (1).
Formula (1): Degree of hydrophobicity (%) = [Me (mL) / (50 + Me (mL))] × 100

The specific external additive fine particles have a higher proportion of silicon atoms in the surface layer than the whole.
As specific external additive fine particles, specifically, those having a structure in which a surface layer made of a silica component is formed on the surface of a core particle made of titania and / or an alumina component are structurally effective. It is preferable because it tends to be obtained. In addition, it is preferable that the said core particle consists of an oxide also containing a silicon atom.
In such a form, the surface layer of the silica component does not necessarily have to completely cover the core particles, and the abundance ratio of the silica component measured by mass with an X-ray photoelectron spectrometer is 30 to 99%. It is preferable that it is preferably 55 to 96%.

The abundance ratio of silica is specifically determined by a method for measuring the abundance ratio R ₂ of silicon atoms in the surface layer of the specific external additive fine particles described above using an X-ray photoelectron spectrometer “ESCA-1000” (manufactured by Shimadzu Corporation). It is measured in the same manner as above.

[Method for producing external additive fine particles]
The method for producing the specific external additive fine particles used in the image forming method of the present invention is not particularly limited, and examples thereof include pyrogenic processes such as a gas phase method and a flame hydrolysis method; a sol-gel method. A plasma method; a precipitation method; a hydrothermal method; a mining process (bergmaennische Verfahren); and a combination of these methods. In terms of easy adjustment of the site where atoms are present, a thermal decomposition method Is preferable, and in particular, a production method employing a gas phase method disclosed in Japanese Patent No. 32025573 can be given.
The method for producing external additive fine particles by the vapor phase method is a method for producing external additive fine particles by introducing raw materials of external additive fine particles into a high-temperature flame in a vapor state or a powder state and oxidizing them. is there.

When the specific external additive fine particles having silicon atoms oriented on the surface are produced by a method in which the raw material is introduced into a high-temperature flame in a vapor state (hereinafter, also referred to as “vapor phase method using vapor”), for example, a high temperature In the flame, steam vaporized by heating the titanium atom source and / or aluminum atom source is introduced in advance, and after vapor growth to some extent, vapor vaporized by heating the silicon atom source is introduced. Is preferable from the viewpoint of production stability.
Examples of the silicon atom source include silicon halides such as silicon tetrachloride, or organosilicon compounds. Examples of the titanium atom source include titanium sulfate and titanium tetrachloride. Further, examples of the aluminum atom source include , Aluminum chloride, aluminum sulfate, sodium aluminate and the like.

On the other hand, in the case of producing specific external additive fine particles having silicon atoms oriented on the surface by a method of introducing raw materials into a high-temperature flame in a powder state (hereinafter also referred to as “powder vapor phase method”). For example, a powder that forms core particles in a high-temperature flame (hereinafter also referred to as “core particle-forming powder”) and a powder that is modified on the surface to form a surface layer (hereinafter referred to as “modifying powder”) In other words, it is preferable to make the core particle-forming powder larger than the modifying powder from the viewpoint of production stability.
This is because the core particle-forming powder and the modifying powder are introduced into the same high-temperature flame, and a plurality of powders aggregate and grow in the high-temperature flame, and grow into particles having a large diameter. It is considered that by making the modifying powder fine particles, the heat receiving area of the modifying powder is increased, and the modifying powder is more easily melted. Therefore, for example, by controlling the temperature of the high temperature flame, the degree of association / growth of the core particle forming powder can be suppressed to a small level, and the conditions for melting and adhering the modifying powder can be found without any special trial and error. it can.
In the above, it is considered that the core particle-forming powder and the modifying powder are simultaneously introduced into a high-temperature flame to modify the surfaces of each other.

In this production method, particles made of a metal oxide such as titania and / or an alumina component are used as the core particle forming powder. The core particle forming powder may be made of an oxide containing silicon atoms.
The core particle-forming powder using a metal oxide can be obtained, for example, by burning a raw material of the metal oxide in a flame. Examples of the metal oxide raw material include those mentioned above as the titanium atom source and the aluminum atom source. These can be used alone or in combination in any combination.
On the other hand, as the modifying powder, one made of silica is used, and specifically, one obtained by burning the silicon atom source mentioned above in a high temperature flame is preferably used. In addition, it is preferable to use an amorphous thing from a viewpoint of environmental safety as a silica.
It is preferable that the silica is bonded and fused before the prototype of the silica cannot be observed on the surface of the core particle by heat.

FIG. 1 is a schematic view showing an example of a production facility for producing external additive fine particles constituting the toner used in the image forming method of the present invention by a powder vapor phase method. The production equipment for producing the specific external additive fine particles according to the present invention by a vapor phase method using powder is not limited to this.
In the case of producing the external additive fine particles by the gas phase method using this powder, for example, when producing the external additive fine particles containing silicon atom, titanium atom and aluminum atom, specifically, as follows: Can get to.

That is, first, the core particle forming powder A housed in the core particle forming powder A tank 21A and the modifying powder B housed in the tank 21B for modifying powder B, respectively, It is introduced into a main burner 26 having a spray nozzle attached to its tip through introduction pipes 23A and 23B by fixed supply pumps 22A and 22B, and further sprayed into a combustion furnace 27 together with an oxygen / steam mixed gas D and ignited by an auxiliary flame. Thus, the high temperature flame 28 is formed.
Then, external additive fine particles are generated by combustion, and the external additive fine particles are cooled in the flue 29 together with the exhaust gas, separated from the exhaust gas by the cyclone 30 and the bag filter 32, and collected by the collectors 31 and 33, respectively. . The exhaust gas separated from the external additive fine particles is exhausted by the exhaust fan 34.
In FIG. 1, 21D is a tank for oxygen / water vapor mixed gas D, and 23D is an introduction pipe for oxygen / water vapor mixed gas.

FIG. 2 is a schematic view showing an example of a production facility for producing the external additive fine particles constituting the toner used in the image forming method of the present invention by a vapor phase method using steam. The production equipment for producing the specific external additive fine particles according to the present invention by the vapor phase method using steam is not limited to this.
In the case of producing external additive fine particles by the vapor phase method using vapor, for example, when producing external additive fine particles containing silicon atoms, titanium atoms, and aluminum atoms, specifically, as follows: Obtainable.

(1) First, a silicon atom source, a titanium atom source, and an aluminum atom source are introduced from a raw material inlet 1 and heated in an evaporator 2 to be vaporized to be vapor related to silicon, vapor related to titanium, and aluminum Get steam.
(2) Next, these vapors are introduced into the mixing chamber 3 together with an inert gas (not shown) such as nitrogen, and then dry air and / or oxygen gas and hydrogen gas are mixed at a predetermined ratio. Thus, a mixed gas is obtained, and this mixed gas is introduced from the combustion burner 4 into a combustion flame (not shown) formed in the reaction chamber 5.
(3) A particle containing silicon atoms, titanium atoms and aluminum atoms is generated by performing a combustion treatment at a temperature of 1000 ° C. to 3000 ° C. in the combustion flame.
(4) After the produced particles are cooled in the cooler 6, the gaseous reaction product is separated and removed in the separator 7. At this time, in some cases, hydrogen chloride adhering to the particle surface is removed in wet air. further,
In the treatment chamber 8, the hydrogen chloride is deoxidized, and is collected by a filter, and the composite oxide particles are collected in the silo 9.

In the manufacturing method as described above, the flow rate ratio of the steam related to silicon introduced into the combustion flame, the steam related to titanium and the steam related to aluminum, the timing of introduction of each steam into the combustion flame, the combustion time, the combustion Since the influence of temperature, combustion atmosphere, and other combustion conditions is reflected in the state of orientation of silicon atoms on the surface of specific external additive fine particles, in the present invention, titanium atoms and aluminum atoms are oriented inside. In order to orient the silicon atoms on the surface, it is preferable to adjust these conditions in a complex manner.
The state in which the silicon atoms are oriented on the surface is, for example, that the timing of introduction of the steam related to silicon introduced into the combustion flame is delayed, or the concentration of the steam related to silicon in all the flowing steam is reacted. It is obtained by making it high in the second half.
Specifically, in the combustion flame, the concentration of the steam related to silicon in the steam having a relatively low electrical resistance preceded by the steam related to titanium and / or the steam related to aluminum (or the total steam flowing in the first half of the reaction). After the crystal has grown to some extent, the silicon-related vapor having a relatively high electrical resistance is introduced (the concentration of the silicon-related vapor in the whole vapor flowing in the second half of the reaction is increased). Is preferable from the viewpoint of production stability.

Although the obtained composite oxide particles may be used as external additive fine particles as they are, it is preferable to subject the composite oxide particles to a hydrophobization treatment.
Examples of the hydrophobic treatment method include the following dry methods.
That is, the hydrophobizing agent is diluted with a solvent such as tetrahydrofuran (THF), toluene, ethyl acetate, methyl ethyl ketone, acetone ethanol and hydrogen chloride saturated ethanol, and the composite oxide particles are forcibly stirred with a blender, etc. Add the diluted solution by dripping or spraying, and mix well. In that case, apparatuses such as a kneader coater, a spray dryer, a Kalmar processor, and a fluidized bed can be used.
Next, the obtained mixture is transferred to a vat and heated in an oven to be dried. Then, it is sufficiently crushed again by a mixer or jet mill. The obtained crushed material is preferably classified as necessary. In the above-described method, when a hydrophobic treatment is performed using a plurality of types of hydrophobizing agents, the treatment may be performed using each of the hydrophobizing agents simultaneously or separately.
In addition to such a dry method, the composite oxide particles are immersed in an organic solvent solution of a coupling agent and then dried; the composite oxide particles are dispersed in water to form a slurry, and then hydrophobic. A hydrophobizing treatment may be performed using a wet method such as a method in which an aqueous solution of an agent is dropped and then the composite oxide particles are precipitated, dried by heating, and crushed.
In the hydrophobization treatment as described above, the temperature during heating is preferably 100 ° C. or higher. When the temperature at the time of heating is less than 100 ° C., the condensation reaction between the composite oxide particles and the hydrophobizing agent becomes difficult to complete.

  Examples of the hydrophobizing agent used in the hydrophobizing treatment include those used as usual surface treating agents such as silane coupling agents such as hexamethyldisilazane, titanate coupling agents, silicone oil, and silicone varnish. . Furthermore, a fluorine-based silane coupling agent, a fluorine-based silicone oil, a coupling agent having an amino group or a quaternary ammonium base, a modified silicone oil, or the like can also be used. These hydrophobizing agents are preferably used in a state dissolved in a solvent such as ethanol.

[Other external additive fine particles]
The external additive fine particles contained in the toner used in the image forming method of the present invention are not limited to the specific external additive fine particles as described above, and other external additive fine particles may be used in combination. .
When other external additive fine particles are used in combination, 50% by mass or more of all external additive fine particles are the specific external additive fine particles according to the present invention. When the specific external additive fine particles are less than 50% by mass of the total external additive fine particles, the high chargeability or excessive antistatic property of the specific external additive fine particles is offset by the influence of the other external additive fine particles. There is a risk of being.

As other external additive fine particles, various inorganic fine particles, organic fine particles and lubricants can be used. For example, inorganic fine particles such as silica, titania, and alumina are preferably used as the inorganic fine particles, and these inorganic fine particles are hydrophobized with a silane coupling agent or a titanium coupling agent. Is preferred. As the organic fine particles, spherical particles having a number average primary particle diameter of about 10 to 2,000 nm can be used. As the organic fine particles, polymers such as polystyrene, polymethyl methacrylate, and styrene-methyl methacrylate copolymer can be used.
As these other external additive fine particles, various types may be used in combination.

[Addition treatment of external additive fine particles]
The toner can be obtained by adding the external additive fine particles as described above to the colored particles to form the toner.
In the addition of the external additive fine particles, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used as a mixing device used for adding the external additive fine particles.

[Addition ratio of external additive fine particles]
The addition ratio of the external additive fine particles is preferably 0.1 to 2.0% by mass with respect to the colored particles.

〔toner〕
The toner used in the image forming method of the present invention contains colored particles and specific external additive fine particles.

[Method for producing colored particles]
The method for producing the colored particles constituting the toner is not particularly limited, and includes a pulverization method, a suspension polymerization method, an emulsion polymerization aggregation method, a dissolution suspension method, a polyester molecular extension method, and other known methods. Can be mentioned. The colored particles constituting the toner are preferably obtained by an emulsion aggregation method, and in particular, miniemulsion polymerization aggregation in which miniemulsion polymerization particles are associated (aggregated / fused) with resin particles having a multistage polymerization configuration by emulsion polymerization. It is preferably obtained by the method.

  Specifically, for example, the miniemulsion polymerization aggregation method is a polymerization property in which a release agent is dissolved in a polymerizable monomer in an aqueous medium in which a surfactant having a critical micelle concentration or less is dissolved. The monomer solution is formed into oil droplets (10 to 1000 nm) using mechanical energy to prepare a dispersion, and a water-soluble polymerization initiator is added to the obtained dispersion to cause radical polymerization. This is a method of obtaining colored particles by associating (aggregating / fusing) the obtained binder resin fine particles. In this miniemulsion polymerization aggregation method, instead of adding a water-soluble polymerization initiator, or while adding the water-soluble radical polymerization initiator, the oil-soluble radical polymerization initiator is added to the monomer solution. It may be added inside. Further, the binder resin fine particles can be composed of two or more layers made of binder resins having different compositions. In this case, the first prepared by miniemulsion polymerization treatment (first-stage polymerization) according to a conventional method. It is possible to employ a method in which a polymerization initiator and a polymerizable monomer are added to a dispersion of resin particles, and this system is polymerized (second-stage polymerization).

As a method for producing colored particles, specifically showing an example of using a miniemulsion polymerization aggregation method,
(1) Dissolving / dispersing a colorant and, if necessary, a toner particle constituent material such as a release agent and a charge control agent in a polymerizable monomer serving as a binder resin to obtain a polymerizable monomer solution Dispersion step (2) Polymerization step in which a polymerizable monomer solution is converted into oil droplets in an aqueous medium and a dispersion of binder resin fine particles is prepared by a mini-emulsion method (3) Salting out of the binder resin fine particles in an aqueous medium Agglomeration and fusing step for agglomerating and fusing to form agglomerated particles (4) aging step for aggregating the agglomerated particles with thermal energy to adjust the shape and obtaining a dispersion of colored particles (5) a dispersion of colored particles Cooling step for cooling (6) Filtration and washing step for solid-liquid separation of the colored particles from the cooled dispersion of colored particles and removal of the surfactant from the colored particles (7) Washed colored particles It is comprised from the drying process which dries.

  Here, the “aqueous medium” means that the main component (50% by mass or more) is made of water. Examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Among these, alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol, which are organic solvents that do not dissolve the resin, are particularly preferable.

[Binder resin]
When the colored particles constituting the toner of the present invention are produced by a pulverization method, a dissolution suspension method or the like, various known resins can be exemplified as the binder resin constituting the colored particles of the toner.
In addition, when the colored particles constituting the toner of the present invention are produced by a suspension polymerization method, a miniemulsion polymerization aggregation method, an emulsion polymerization aggregation method, or the like, a polymerizable monomer for obtaining each resin constituting the toner Examples of the body include various known polymerizable monomers such as vinyl monomers. Moreover, as a polymerizable monomer, it is preferable to use what has an ionic dissociation group in combination. Furthermore, as the polymerizable monomer, a cross-linked binder resin can be obtained using a polyfunctional vinyl monomer.

[Colorant]
As the colorant constituting the colored particles of the toner of the present invention, a known inorganic or organic colorant can be used.
The amount of the colorant added is 1 to 30% by mass, preferably 2 to 20% by mass, based on the colored particles.

(Internal additive)
The colored particles constituting the toner of the present invention may contain a release agent and a charge control agent as necessary. Various known compounds can be used as the release agent and charge control agent.

[Particle size of colored particles]
The particle diameter of the colored particles constituting the toner particles used in the image forming method of the present invention is preferably 3 to 8 μm in number average particle diameter. In the case of forming colored particles by a polymerization method, the particle size is controlled by the concentration of the aggregating agent, the amount of the organic solvent added, the fusing time, and the composition of the polymer itself in the above-described toner production method. can do.
The number average particle size is 3 to 8 μm, so that reproducibility of fine lines and high image quality of photographic images can be achieved, and the amount of toner consumption can be reduced as compared with the case of using a large particle size toner. Can do.

(Developer)
The toner used in the image forming method of the present invention can be used as a magnetic or non-magnetic one-component developer, but may be used as a two-component developer by mixing with various known carriers.
The volume average particle diameter of the carrier is preferably 20 to 100 μm, more preferably 25 to 80 μm. The volume average particle 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.

[Fixing device]
The developer described above is used in an image forming method for fixing in the following fixing device.
FIG. 3 is an explanatory diagram showing an example of the configuration of the fixing device used in the image forming method of the present invention.
The fixing device includes a heating roller 12 in contact with one surface of the image support P on which the toner image T is formed, an end pressing member 17, belt guide members 18a and 18b, the end pressing member 17, and a belt guide member 18a. , 18b, an endless fixing belt 15 stretched around the fixing belt 15, and a pressure rotating body 13 including a pressure contact mechanism 16 disposed inside the fixing belt 15. The heating roller 12 and the heating roller 12 A nip portion N is formed by a pressure contact portion between the pressure rotating body 13 and the pressure contact mechanism 16 of the pressure rotating body 13.
In the fixing device provided with such a fixing belt 15, since the nip portion N is configured to be wide, stable fixing performance can be ensured.

  The heating roller 12 includes a heating source H made of, for example, a halogen heater. The heating roller 12 includes a metal cylindrical core 121 having the heating source H disposed therein, and an outer periphery of the cylindrical core 121. It is composed of a cylindrical roll composed of a heat-resistant elastic body layer 122 formed on the surface and a release layer 123 formed on the outer peripheral surface of the heat-resistant elastic body layer 122, for example, 194 mm / sec. Rotated at linear speed.

The cylindrical metal core 121 constituting the heating roller 12 is formed of a metal having high thermal conductivity such as iron, aluminum, stainless steel (SUS), and the outer diameter is, for example, 30 mm, and the wall thickness is, for example, 1 .8 mm, and the length is, for example, 360 mm.
The heat-resistant elastic body layer 122 is composed of an elastic body having high heat resistance, and it is particularly preferable to use an elastic body such as rubber or elastomer having a JIS-A hardness of 15 to 45 °, such as silicone rubber or fluororubber. Specifically, for example, a silicone HTV rubber having a JIS-A hardness of 35 ° can be coated on the cylindrical metal core 121 with a thickness of 600 μm.
As the release layer 123, for example, a heat-resistant resin such as a silicone resin or a fluororesin is used, and it is particularly preferable to use a fluororesin from the viewpoint of the releasability to the toner and the wear resistance. Examples of the fluororesin include tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). The thickness of the release layer 123 is preferably 5 to 30 μm, and the surface thereof is preferably in a mirror state.

  Further, a temperature sensor 19 is disposed in contact with the surface of the heating roller 12, and based on a temperature measurement value by the temperature sensor 19, a control unit (not shown) of the image forming apparatus controls the heating source H. By controlling lighting-off, the surface temperature of the heating roller 12 is maintained at a predetermined set temperature (for example, 175 ° C.).

  The fixing belt 15 constituting the pressure rotator 13 is formed of an endless belt having a seam formed in a cylindrical shape so that an image defect caused by a seam does not occur in an output image. The pressure contact member 16A and the end pressure contact member 17 constituting the pressure contact mechanism 16 disposed on the inner side of the belt 15, belt guide members 18a and 18b, and edge guide members (not shown) disposed on the side end portions of the fixing belt 15. Z)) is supported in a freely circulating manner. Then, in the nip portion N, the heat roller 12 is circulated and moved.

  The fixing belt 15 can be constituted by, for example, a base layer and a release layer formed on the outer peripheral surface or both surfaces of the base layer. The base layer is formed of thermosetting polyimide, thermoplastic polyimide, polyamide, polyamideimide, or the like, and has a thickness of, for example, 30 to 200 μm. The release layer is made of, for example, a fluororesin such as PFA, PTFE, FEP, and the thickness thereof is, for example, 5 to 100 μm. As an example of the fixing device, for example, a configuration in which a release layer made of PFA having a thickness of 30 μm is laminated on a base layer made of thermosetting polyimide having a peripheral length of 94 mm, a thickness of 75 μm, and a width of 320 mm can be exemplified. .

  The press contact mechanism 16 that constitutes the pressurizing rotating body 13 is composed of a press contact member 16A and an end press contact member 17, and the press contact member 16A that constitutes the press contact mechanism 16 holds the heating roller 12 by a spring or an elastic body. For example, it is supported by a holder (not shown) in a state of being pressed with a load of 350 N.

The pressure contact mechanism 16 is disposed inside the fixing belt 15 so as to be pressed against the heating roller 12 via the fixing belt 15.
As the pressure contact member 16A, an elastic body such as silicone rubber or fluorine rubber can be used, and the shape of the pressure contact member 16A on the side of the heating roller 12 is a shape that follows the outer peripheral surface of the heat roller 12 in the operating state. .

  The end pressure contact member 17 constituting the pressure contact mechanism 16 is disposed on the exit side of the nip portion N and applies a peeling force to the heating roller 12, thereby forming a down curl on the image support P to form the image support P. This makes it easy to peel from the heating roller 12. Specifically, the surface of the heating roller 12 is distorted (dented) by locally pressing the surface of the heating roller 12 with a pressure larger than the pressure at the central portion of the nip N by the end pressure contact member 17. Thus, the image support P can be easily peeled off from the heating roller 12.

  The end pressure contact member 17 is formed of a heat-resistant resin such as polyphenylene sulfide (PPS), polyimide, polyester, polyamide, or a metal such as iron, aluminum, SUS, and the shape of the end pressure contact member 17 is as follows. The outer surface shape of the nip portion N is formed as a convex curved surface having a constant radius of curvature. The end pressure member 17 is disposed at a position where the fixing belt 15 is wrapped around the heating roller 12 at a winding angle of about 40 ° by the pressure mechanism 16A. The load is preferably larger than the pressing load of the pressure contact mechanism 16, and is preferably 1.1 times or more, for example.

  In the fixing device as described above, when the heating roller 12 is connected to a drive motor (not shown) and rotated in the direction of arrow C, the fixing belt 15 is a nip where the fixing belt 15 is in contact with the heating roller 12 following this rotation. When the image support P that has moved in the same direction at the portion N and is transferred with the toner image is conveyed to the nip portion N and passes through the nip portion N, the toner image T on the image support P is transferred to the nip portion N. And the heat applied from the heating roller 12 for fixing. The image support P is peeled away from the heating roller 12 by passing through the nip N while being pressed by the end pressure contact member 17 at the outlet of the nip N.

(Image support)
The image support used in the image forming method of the present invention is a support for holding a toner image, and specifically, coating of plain paper, fine paper, art paper, coated paper, etc. from thin paper to thick paper. Various kinds of printed paper, commercially available Japanese paper, postcard paper, plastic films for OHP, cloth, and the like can be used, but the invention is not limited to these.

According to the image forming method as described above, the toner contains specific external additive fine particles, and the specific external additive fine particles have an abundance ratio of silicon atoms in the surface layer of the silicon atoms in the whole. It is higher than the abundance ratio and does not shift to the heating roller due to peeling charging near the exit of the nip portion of the fixing device, so that the toner component does not shift, and as a result, excessive charging is performed while having sufficient chargeability. The occurrence of the electrostatic offset phenomenon can be suppressed.
The reason why the specific external additive fine particles contained in the toner can suppress the occurrence of electrostatic offset phenomenon by suppressing excessive charging while having sufficient chargeability is that the specific external additive fine particles are While the silica is easily charged by the silicon atoms present in the surface layer and has sufficient chargeability due to the property of easily retaining the charge, the charge of the particles inside the particles due to the titanium atoms and / or aluminum atoms present therein can be obtained. It is assumed that excessive charging can be suppressed by leakage.

  As mentioned above, although embodiment of this invention was described concretely, embodiment of this invention is not limited to said example, A various change can be added.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

[Production Example 1 of resin particle dispersion]
(First stage polymerization)
A 5 L reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device was charged with a solution prepared by dissolving 8 g of sodium dodecyl sulfate in 3 L of ion-exchanged water and stirred at a stirring speed of 230 rpm under a nitrogen stream. The internal temperature was raised to 80 ° C. After the temperature rise, a solution in which 10 g of potassium persulfate was dissolved in 200 g of ion-exchanged water was added, the temperature was again set to 80 ° C., 480 g of styrene, 250 g of n-butyl acrylate, 68.0 g of methacrylic acid and n-octyl-3- Polymeric monomer solution containing 16.0 g of mercaptopropionate was added dropwise over 1 hour, then polymerized by heating and stirring at 80 ° C. for 2 hours, and resin particle dispersion containing resin particles (1h) A liquid (1H) was prepared.

(Second stage polymerization)
A 5 L reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introducing device was charged with a solution prepared by dissolving 7 g of sodium polyoxyethylene-2-dodecyl ether sulfate in 800 ml of ion-exchanged water and heated to 98 ° C. , 260 g of the above resin particle dispersion (1H), 245 g of styrene, 120 g of n-butyl acrylate, 1.5 g of n-octyl-3-mercaptopropionate, 67 g of the release agent “HNP-11” at 90 ° C. Add the dissolved polymerizable monomer solution, and mix and disperse for 1 hour using a mechanical disperser “CREARMIX” (M Technique Co., Ltd.) with a circulation path to prepare a dispersion containing emulsified particles (oil droplets). did.
Next, an initiator solution in which 6 g of potassium persulfate was dissolved in 200 ml of ion-exchanged water was added to this dispersion, and the system was heated and stirred at 82 ° C. for 1 hour to polymerize the resin particles (1 hm ) Containing resin particle dispersion (1HM) was prepared.

(3rd stage polymerization)
A solution prepared by dissolving 11 g of potassium persulfate in 400 ml of ion-exchanged water was added to the above resin particle dispersion (1HM), and styrene 435 g, n-butyl acrylate 130 g, methacrylic acid 33 g and n were added at a temperature of 82 ° C. -A polymerizable monomer solution consisting of 8 g of octyl-3-mercaptopropionate was added dropwise over 1 hour. After completion of the dropwise addition, polymerization was carried out by heating and stirring for 2 hours, followed by cooling to 28 ° C. to obtain a resin particle dispersion [A] containing resin particles a. The particle diameter of the resin particles a in the resin particle dispersion [A] was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.). The volume-based median diameter was 150 nm. It was. Moreover, it was 45 degreeC when the glass transition point temperature of this resin particle a was measured.

[Production Example 1 of Colorant Fine Particle Dispersion]
While stirring a solution obtained by dissolving 90 g of sodium dodecyl sulfate in 1600 ml of ion-exchanged water, 420 g of carbon black “Regal 330R” (manufactured by Cabot) is gradually added, and then a stirrer “Clearmix” (M Technique Co., Ltd.). Dispersion of colorant fine particles [Bk] was prepared.

[Production Examples 2 to 4 of Colorant Fine Particle Dispersion]
In Production Example 1 of a dispersion of colorant fine particles, 420 g of carbon black was added to each of C.I. I. Pigment Yellow 74, 310 g, C.I. I. Pigment Red 122 310g, C.I. I. Colorant fine particle dispersions [Y], [M], and [C] were prepared in the same manner except that Pigment Blue 15 was replaced with 310 g.

[Production Example 1 of colored particles]
In a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction device, 300 g of resin particle dispersion [A], 1400 g of ion-exchanged water, and dispersion of colorant fine particles [Bk ] And 120 g of sodium polyoxyethylene-2-dodecyl ether sulfate dissolved in 120 ml of ion-exchanged water, the temperature of the solution was adjusted to 30 ° C., and 5N sodium hydroxide aqueous solution was added to adjust the pH. Adjusted to 10. Next, an aqueous solution in which 35 g of magnesium chloride was dissolved in 35 ml of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring, and the temperature was raised after holding for 3 minutes. The particle growth reaction was continued while maintaining the temperature at 90 ° C. In this state, the particle size of the associated particles is measured with “Coulter Multisizer III”, and when the desired particle size is reached, an aqueous solution in which 150 g of sodium chloride is dissolved in 600 ml of ion-exchanged water is added to increase particle growth. Further, the fusion between the particles was allowed to proceed until the average circularity was 0.965 as measured by “FPIA-2100” by heating and stirring at a liquid temperature of 98 ° C. as a fusion step. Thereafter, the solution was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 4.0, and stirring was stopped.

  The colored particles produced in the above process are solid-liquid separated with a basket-type centrifuge “MARK III model number 60 × 40” (Matsumoto Kikai Co., Ltd.) to form a wet cake of colored particles. Was washed with ion exchange water at 45 ° C. until the electrical conductivity of the filtrate reached 5 μS / cm using the basket-type centrifuge, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). It dried until it became 5 mass%, and colored particle [Bk] was obtained.

[Production Examples 2 to 4 of colored particles]
In Production Example 1 of colored particles, coloring was performed in the same manner except that the dispersions [Y], [M], and [C] of the colorant fine particles were used instead of the dispersion [Bk] of the colorant fine particles, respectively. Particles [Y], [M], and [C] were prepared.

[Production Example 1 of External Additive Fine Particles]
Using the production apparatus shown in FIG. 2, silicon tetrachloride vapor [A], titanium tetrachloride vapor [B], and aluminum chloride vapor [C] are not flowed at the flow rates shown in the initial introduction amount column of Table 1. A composite containing silicon atoms, titanium atoms and aluminum atoms introduced into a reaction chamber together with an active gas and burned for 0.3 seconds at a combustion temperature of 2,000 ° C. with a mixture of hydrogen and air mixed at a predetermined ratio Particles were generated and collected by a filter after cooling.
The obtained composite particles were dechlorinated by heating at 500 ° C. for 1 hour in an oven in an air atmosphere, and 500 parts by mass of this was charged into a high-speed stirring mixer equipped with a jacket for heating and stirring at 500 rpm. Then, 25 parts by mass of pure water was sprayed and supplied under sealing, and the mixture was further stirred for 10 minutes. Subsequently, 25 parts by mass of hexamethyldisilazane was added, and the mixture was stirred for 60 minutes in a sealed state, and then aerated with nitrogen at 150 ° C. with stirring to remove the generated ammonia gas and the remaining treatment agent. External additive fine particles [1] comprising composite oxide particles were obtained.
Table 1 shows the coefficient (R ₁ ) / (R ₂ ), number average primary particle size, BET specific surface area, bulk density, and degree of hydrophobicity of the obtained external additive fine particles [1]. The coefficient (R ₁ ) / (R ₂ ), number average primary particle size, BET specific surface area, bulk density, and degree of hydrophobicity are calculated based on the above measurement procedure.

[Production Examples 2 to 5 of external additive fine particles]
In Production Example 1 of the external additive fine particles, silicon tetrachloride vapor [A], titanium tetrachloride vapor [B] and aluminum chloride vapor [C] were initially introduced from the main route as shown in Table 1 as reaction raw materials. Introduced into the reaction chamber at the flow rate shown in the quantity column, and introduced into the reaction chamber at the flow rate shown in the late introduction quantity column of Table 1 from another route (not shown) as the late raw material of the reaction, to form silicon atoms, titanium atoms and aluminum External additive fine particles [2] to [5] were obtained in the same manner except that composite particles containing atoms were produced.
Table 1 shows the coefficient (R ₁ ) / (R ₂ ), number average primary particle diameter, BET specific surface area, bulk density, and degree of hydrophobicity of the obtained external additive fine particles [2] to [5].

[Production Examples 6 to 10, 13 to 15 of External Additive Fine Particles]
In the external additive fine particle production example 1, the external additive fine particles [6] to [6] to [6] are similarly produced except that the raw material introduced into the reactor of the combustion burner is changed to the raw materials shown in Table 1 and the mixing ratio thereof. 10] and external additive fine particles [13] to [15].
Coefficients (R ₁ ) / (R ₂ ), number average primary particle diameter, BET specific surface area, bulk density of the obtained external additive fine particles [6] to [10] and external additive fine particles [13] to [15] Table 1 shows the degree of hydrophobicity.

[Production Example 11 of External Additive Fine Particles]
Titanium dioxide particles [t] obtained in the same manner as in Production Example 14 of external additive fine particles and silica powder [s] obtained in the same manner as in Production Example 13 of external additive fine particles were previously 9% by mass. 1 is mixed in a resin bag, put into a tank using the manufacturing apparatus shown in FIG. 1, and conveyed through an introduction pipe together with air as a carrier gas at a supply rate of 4 kg / hour, and a nozzle Erupted from. At this time, the flow velocity of the air nozzle was 48 m / sec.
After the reaction, cooling air was introduced into the combustion furnace so that the high-temperature residence time in the combustion furnace was 0.3 seconds or less, and then the fine powder produced using a polytetrafluoroethylene bag filter [P ] Was collected.
The collected fine powder [P] is dechlorinated by heating in an oven at 500 ° C. for 1 hour in an air atmosphere, and 500 parts by mass of this is charged into a high-speed stirring mixer with a jacket for heating and cooling, and 500 rpm While being stirred at 25 ° C., 25 parts by mass of pure water was sprayed in a sealed state, and then stirring was continued for 10 minutes. Subsequently, 25 parts by mass of hexamethyldisilazane was added, and stirring was performed for 60 minutes in a sealed state, followed by stirring and heating to remove the generated ammonia gas and the remaining treating agent while ventilating nitrogen at 150 ° C., External additive fine particles [11] were obtained.
Table 1 shows the coefficient (R ₁ ) / (R ₂ ), number average primary particle diameter, BET specific surface area, bulk density, and degree of hydrophobicity of the obtained external additive fine particles [11].

[Production Example 12 of External Additive Fine Particles]
In the external additive fine particle production example 11, the aluminum dioxide [a] obtained in the same manner as the external additive fine particle production example 15 was used instead of the titanium dioxide particles [t]. External additive fine particles [12] were obtained.
Table 1 shows the coefficient (R ₁ ) / (R ₂ ), number average primary particle size, BET specific surface area, bulk density, and degree of hydrophobicity of the obtained external additive fine particles [12].

[Toner Production Examples Bk1 to Bk15]
Toner particles [Bk1] to [Bk15] were prepared by adding external additive fine particles [1] to [15] to the colored particles [Bk] so as to have the addition amounts shown in Table 2 and mixing with a Henschel mixer. . Note that the shape and particle size of these toner particles did not change depending on the addition of the external additive fine particles. The toners [Bk1] to [Bk4] and [Bk6] to [Bk12] are toners according to the present invention, and the toners [Bk5] and [Bk13] to [Bk15] are comparative toners.

[Toner Production Examples Y1 to Y15]
Toner particles [Y1] to [Y15] were prepared by adding external additive fine particles [1] to [15] to the colored particles [Y] so as to have the addition amounts shown in Table 2 and mixing with a Henschel mixer. . Note that the shape and particle size of these toner particles did not change depending on the addition of the external additive fine particles. Toners [Y1] to [Y4] and [Y6] to [Y12] are toners according to the present invention, and toners [Y5] and [Y13] to [Y15] are toners for comparison.

[Toner Production Examples M1 to M15]
External additive fine particles [1] to [15] were added to the colored particles [M] so as to have the addition amounts shown in Table 2, and mixed by a Henschel mixer to prepare toners [M1] to [M15]. . Note that the shape and particle size of these toner particles did not change depending on the addition of the external additive fine particles. Toners [M1] to [M4] and [M6] to [M12] are toners according to the present invention, and toners [M5] and [M13] to [M15] are toners for comparison.

[Toner Production Examples C1 to C15]
Toner particles [C1] to [C15] were prepared by adding external additive fine particles [1] to [15] to the colored particles [C] so as to have the addition amounts shown in Table 2 and mixing with a Henschel mixer. . Note that the shape and particle size of these toner particles did not change depending on the addition of the external additive fine particles. Toners [C1] to [C4] and [C6] to [C12] are toners according to the present invention, and toners [C5] and [C13] to [C15] are toners for comparison.

[Production Examples of Developers Bk1 to Bk15, Y1 to Y15, M1 to M15, C1 to C15]
Each of toners [Bk1] to [Bk15], [Y1] to [Y15], [M1] to [M15], and [C1] to [C15] are coated with a silicone resin and have a volume average particle diameter of 60 μm. Developers [Bk1] to [Bk15], [Y1] to [Y15], [M1] to [M15], and [C1] to [C15] are prepared by mixing the carrier so that the toner concentration is 6%. did.

[Examples 1-11, Comparative Examples 1-4]
The developers [Bk1] to [Bk15], [Y1] to [Y15], [M1] to [M15], and [C1] to [C15] obtained as described above ((Bk1) / [Y1] / [M1] / [C1]) to ([Bk15] / [Y15] / [M15] / [C15]) in combination with the digital copier “bizhub PRO C450” (manufactured by Konica Minolta) The following live-action test was performed using a device equipped with a fixing device, and the occurrence of electrostatic offset phenomenon described in detail below was evaluated. The results are shown in Table 2.

[Fixing device]
・ Heat source: halogen heater lamp, rated power: 600W
・ Cylinder core of heating roller: Material: Iron, Dimensions: Outer diameter 30mm, Wall thickness 1.8mm, Length 360mm
Heat-resistant elastic layer of heating roller: material: silicone HTV rubber with JIS-A hardness 35 °, dimensions: thickness 600 μm
・ Releasing layer of heating roller: Material: PFA, Dimensions: Thickness 30 μm, Surface state: Mirror surface ・ Rotating speed of heating roller: Linear speed: 194 mm / sec
Fixing belt base layer: Material: Thermosetting polyimide, Dimensions: Perimeter 94 mm, thickness 75 μm, width 320 mm
-Release layer of fixing belt: material: PFA, dimensions: thickness 30 μm
・ Pressure contact member: Material: Silicone, Load: 350N
-End pressure contact member: Material: Polyphenylene sulfide (PPS), winding angle: 40 ° C., load: 700 N
-Nip part: Width: 10mm

[Evaluation of electrostatic offset phenomenon]
Under a low-temperature and low-humidity environment (10 ° C., 15% RH), after outputting 50 halftone solid images having a relative image density of 0.6, a blank image was output, and the blank image was visually observed.
When no contamination due to toner and toner components has occurred, “◎”,
If the toner and toner components are contaminated but the level is almost inconspicuous,
When the contamination due to the toner and the toner component is periodically observed, it is a level where there is no practical problem.
“X” indicates that the contamination due to the toner and the toner component is periodically observed as a belt-like shape and cannot be used.
As evaluated.

  As is clear from the results in Table 2, in Examples 1 to 11 according to the image forming method of the present invention, it was confirmed that the occurrence of electrostatic offset phenomenon was suppressed while sufficient chargeability was obtained. .

It is the schematic which shows an example of the manufacturing equipment which manufactures the external additive fine particle which comprises the toner used for the image forming method of this invention by the gaseous-phase method by powder. It is the schematic which shows an example of the manufacturing equipment which manufactures the external additive fine particle which comprises the toner used for the image forming method of this invention by the vapor phase method by a vapor | steam. FIG. 2 is a cross-sectional view illustrating an example of a configuration of a fixing device used in the image forming method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw material inlet 2 Evaporator 3 Mixing chamber 4 Combustion burner 5 Reaction chamber 6 Cooler 7 Separator 8 Processing chamber 9 Silo 12 Heating roller 121 Cylindrical metal core 122 Heat-resistant elastic body layer 123 Release layer 13 Pressing rotary body 15 Fixing belt 16 Pressure contact mechanism 16A Pressure contact member 17 End pressure contact members 18a, 18b Belt guide member 19 Temperature sensor H Heating source N Nip part P Image support T Toner images 21A, 21B, 21D Tanks 22A, 22B Constant supply pumps 23A, 23B , 23D Introduction tube A Core particle forming powder B Modification powder D Oxygen / steam mixed gas 26 Main burner 27 Combustion furnace (reaction tube)
28 High-temperature flame 29 Flue 30 Cyclone 32 Bag filter 31, 33 Recovery unit 34 Blower

Claims (4)

A toner image formed by visualizing the electrostatic latent image formed on the electrostatic latent image carrier with a toner containing at least colored particles and external additive fine particles is transferred to an image support and fixed. In an image forming method for fixing in an apparatus,
The fixing device includes a heating roller, an endless fixing belt press-contacted to the heating roller, a press-contact member configured to conform to the outer shape of the heating roller in an operating state inside the fixing belt, and the press-contact member And a pressure contact mechanism composed of an end pressure contact member that is disposed on the downstream side of the heating roller and applies a peeling force to the heating roller.
The external additive fine particles are composed of a composite oxide containing silicon atoms and titanium atoms and / or aluminum atoms, and the abundance ratio of silicon atoms in the surface layer is greater than the abundance ratio of silicon atoms in the whole. An image forming method characterized by being high.   The image forming method according to claim 1, wherein the external additive fine particles have a total content mass of titanium atoms and aluminum atoms larger than a content mass of silicon atoms. The external additive fine particles, the abundance ratio of silicon in the entire atoms when R _1, the existence ratio of silicon atoms in the surface layer and R _2, the coefficient _{(R 1) / (R 2} ) is 0.7 or less The image forming method according to claim 1, wherein the image forming method is provided.   The image forming method according to claim 1, wherein the external additive fine particles have a number average primary particle diameter of 20 to 200 nm.