JP2009288379A - Image-forming method, fixing method, and toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image-forming method which satisfies both low-temperature fixability and low temperature-offset resistance even if a fixing member having a mold-releasing layer is used. <P>SOLUTION: The image-forming method has a fixing process in which a recording material carrying a toner image passes through a nip part, which is formed with a pressing member 63 and a rotatable image heating member 30, and thereby the toner image is heated, pressed and then fixed. In this case, the image heating member is a roller having a mold-releasing layer as an uppermost layer, a heat accumulating layer 33 under the mold-releasing layer, and an elastic layer 32 under the heat accumulating layer. The image heating member includes a heat-conductive filler having thermal conductivity of 5.0 W/mK or larger. The heat-conductive filler is Al and/or a Zn compound. The activation energy Ea of the toner which is found from a shift factor is 110 kJ/mol or smaller in a master curve at 120°C as a reference temperature. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming method, a fixing method, and a toner used for electrophotography, electrostatic recording, magnetic recording, and the like.

  Conventionally, in an image forming apparatus, a contact heating type apparatus has been widely used as an apparatus for heating and fixing an unfixed toner image formed and supported on a recording material as a permanently fixed image. In this contact heating type fixing device, a rotating member (hereinafter referred to as a fixing roller) whose surface temperature in contact with a recording material is heated to a predetermined fixing temperature is brought into contact with the recording material at a nip portion to perform recording. The unfixed toner image on the material is heat-fixed as a permanently fixed image.

  The fixing process for fixing the developer such as toner to the recording material requires a lot of energy and is the final process that is actually output at hand, and is therefore an important process for determining the image quality of the obtained image.

  In general, when the toner fixing property and releasability from the fixing member are not sufficient, or when the toner passes through the fixing portion without being sufficiently melted and fixed, a phenomenon of scattering to the rear end side of the recording material occurs. In some cases (hereinafter referred to as “fixing tail” in the present invention).

  In the method for developing the toner, a magnetic one-component development system using a magnetic toner is preferably used because it does not require a carrier and is advantageous for downsizing the apparatus. The magnetic toner used in the magnetic one-component development system contains a considerable amount of fine powdery magnetic powder, wax, and the like mixed and dispersed. Therefore, the presence of the magnetic substance, wax, and binder resin determines the toner fixability. The structure control is important because it greatly affects the releasability.

  In this way, by optimizing the fixing system including the image forming method and the toner structure control, it is possible to shorten the warm-up time, improve the fixing property, and to prevent the image defects such as the low temperature offset resistance and the fixing tailing. In order to reduce energy consumption and improve image quality, further improvements are desired.

  As a heating method for the fixing roller, there is a conventional internal heating method. In this method, heating means (heating source: heater or the like) is disposed inside the fixing roller, and the fixing roller is heated from the inside to heat the surface of the fixing roller to a predetermined fixing temperature. However, the internal heating method takes time because the entire roller needs to be heated, and is inferior in on-demand performance.

  Various studies have been made in order to cope with the on-demand property, and the film heat fixing method is a useful fixing method. This is a system in which the heater directly heats through the film, so that the heat of the heater can be efficiently applied to the recording material. However, since film heat fixing uses a film, the film may be broken during long-term use.

  As a new fixing method to eliminate such concerns, an external heating method (surface heating method) has been studied.

  Since the external heating type apparatus directly heats the fixing roller from the outside with a ceramic heater, a halogen heater, or the like, the surface of the fixing roller can be rapidly heated. Therefore, the warm-up time compared to the internal heating system and the time from when a print signal is received until the recording material on which the unfixed toner image is formed is heated and fixed (hereinafter referred to as the first printout time). Can be shortened. Along with these, on-demand is also improved, which is preferable. Moreover, since the above-mentioned malfunction does not arise from not using a film, it is preferable.

  As a technique related to such an external heating method, for example, there is a technique in which the inside of the fixing roller is thermally insulated and the outermost layer is made highly thermally conductive by inserting a heat conductive filler (see Patent Documents 1 and 2). However, although this technology shortens the warm-up time and increases on-demand, such a heat conductive filler has a very high affinity with toner, so it is disadvantageous for wrapping, and low temperature offset is likely to occur. There is room for improvement.

  In order to improve wrapping and low temperature offset, in Patent Document 3, PFA (copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether) having high releasability is arranged on the surface layer to reduce the adhesiveness to paper. Techniques for making them disclosed are disclosed. However, if the surface layer portion is covered with PFA, the heat transfer efficiency is lowered, the fixing temperature becomes high and the on-demand property is inferior, so there is room for further improvement.

  Further, in order to improve the wrapping resistance, it is very effective to provide a release layer having excellent releasability from the recording material on the surface of the image heating member, and various studies have been made (Patent Documents). 4, 5, 6). However, the heat transfer efficiency from the image heating member to the recording material decreases due to the reduction of the heat capacity of the surface layer. Therefore, the heating device needs to give high energy to the image heating member. In addition, low temperature offset resistance is not sufficient, and fixing tailing reduction is not sufficient, leaving room for improvement.

  Accordingly, there is a need for an image forming method capable of fixing at a lower temperature and improving low-temperature offset resistance and fixing tailing.

  In response to such a demand, for example, Patent Document 7 uses 12-hydroxystearic acid as a styrene-based resin, thereby making it possible to increase the production stability at the time of toner kneading, and serving as a fixing aid to fix the toner. Attempts have been made to improve.

  In Patent Document 8, emulsion polymerization is carried out using wax as a seed, and the wax is encapsulated and finely dispersed to try to improve the fixing property.

  In Patent Document 9, the activation energy of the toner is controlled to 30 kcal / mol or more and 45 kcal / mol or less to improve low-temperature fixing as a color toner.

  However, even in such a case, there is still room for improvement from the viewpoint of achieving both high image quality such as reduction of energy during fixing and reduction of fixing tail.

  Patent Documents 10 and 11 attempt to increase the releasability between the toner and the pressure member by including the thermal conductivity of the pressure member and the toner containing a hydrophobic metal oxide. There is still room for improvement in terms of both energy reduction and image quality.

  Patent Document 12 attempts to improve the low-temperature fixability and high-temperature offset resistance of the toner by controlling the THF-insoluble content and rheological properties of the toner. There is still room for improvement in terms of high releasability by controlling the structure of the resin component.

  Patent Documents 13, 14, and 15 attempt to reduce fixing tail by using two types of external additives having different particle diameters or controlling the molecular weight of a resin in a fixing system using film heating. However, even if it is applied as it is to an external heating type fixing system as in the present invention, it is difficult to obtain a great effect.

  In Patent Document 16, an attempt is made to reduce the toner scattering and tailing by melting the toner by using a core-shell structure for the toner and including a preheating device in the image forming apparatus. This is disadvantageous in terms of cost, and there is still room for improvement in terms of high releasability from the fixing roller.

  Therefore, in the image forming method using the image heating member having the release layer, the image forming method and the toner are improved to improve the low temperature fixing property, the low temperature offset resistance, and the image defect such as the fixing tail. There is a need for technology that makes it possible.

JP 2004-317788 A JP 2007-121441 A JP 2004-86202 A JP 2003-173096 A JP 2002-278338 A JP 2003-186327 A JP 2001-305791 A Japanese Patent Laid-Open No. 2002-082487 Japanese Patent Laid-Open No. 06-011898 JP 2002-040708 A JP 2002-148845 A JP-A-11-143127 JP 2002-23416 A JP 2003-207930 A JP 2004-53622 A JP 2006-154244 A

  An object of the present invention is to provide an image forming method and a toner which solve the above-mentioned problems. That is, an object of the present invention is to provide an image forming method, a fixing method, and a toner that can achieve both low-temperature fixability, low-temperature offset resistance, and further reduction in fixing tail even when a fixing member having a release layer is used. It is.

  As a result of intensive studies, the present inventors have optimized the image forming method, the fixing method, and the toner configuration, and the image heating member has a release layer and is heated from the outside, so that a short first printout time can be obtained. Achieve a synergistic effect by improving the releasability without impairing the fixability and further improving the fixability and releasability by controlling the structure of the toner used as the developer. It has been found that it is effective for fixing property, low-temperature offset resistance, and fixing tailing suppression.

That is, a charging step of charging the electrostatic latent image carrier with a charging means, an exposure step of exposing the charged electrostatic latent image carrier to form an electrostatic latent image, and developing the electrostatic latent image with toner A developing process for forming a toner image, a transfer process for transferring the toner image to a recording material with or without an intermediate transfer member, and an image that can rotate the recording material carrying the toner image with a pressure member. In an image forming method including a fixing step of fixing by heating and pressing by passing a nip formed by a heating member,
The image heating member is heated from the outermost surface by an external heating means,
The image heating member is a roller having a release layer having a thickness of 5 μm or more and 200 μm or less as an outermost layer, a heat storage layer as a lower layer, and an elastic layer as a lower layer,
The image heating member contains a heat conductive filler having a heat conductivity of 5.0 W / mK or more,
The thermally conductive filler is Al and / or Zn compound,
When the surface of the image heating member is measured by EPMA (electron beam microanalyzer), the abundance ratio of Al and / or Zn elements derived from the heat conductive filler is set to 0. 0 with respect to the total amount of elements detected by EPMA. 10 mass% or more and 3.00 mass% or less,
Heat capacity per unit area of the heat storage layer is not more than 100 J / m ² K or more 600J / m ² K,
The toner is an image forming method in which the activation energy Ea (kJ / mol) obtained from the shift factor aT at that time is 110 (kJ / mol) or less in the master curve when the reference temperature is 120 ° C. Features.

  In the image forming method, it is desirable that the surface roughness Rz of the image heating member is 1.0 μm or more and 10.0 μm or less.

  In the image forming method, it is preferable that the release layer of the image heating member is a solid rubber layer mainly containing fluororubber.

  In the image forming method, it is desirable that the heat storage layer of the image heating member contains a heat conductive filler in an amount of 10% by mass to 50% by mass.

  In the image forming method, the image heating member preferably has a micro hardness of 30 ° or more and 68 ° or less.

  In the image forming method, the elastic layer preferably has a thermal conductivity of 0.15 W / mK or less.

In the image forming method, in the master curve when the toner is 120 ° C. as the reference temperature, the activation energy obtained from the shift factor aT at that time is Ea (kJ / mol), and the toner is tetrahydrofuran (THF). It is desirable that the following relational expression (1) is satisfied when A% of the THF-insoluble component derived from the component of the binder resin when the Soxhlet extraction is performed is performed.
Ea / A ≦ 5.0 (Formula 1)

  In the image forming method, it is preferable that the molecular weight of the peak top is 15000 or more and 30000 or less in gel permeation chromatography (GPC) measurement of THF soluble matter of the toner.

  In the image forming method, the average circularity of the toner is preferably 0.950 or more.

  In the image forming method, the toner is preferably a toner obtained by polymerizing a polymerizable monomer composition in an aqueous medium.

  In the image forming method, it is preferable that the toner contains at least a binder resin, a wax, and a magnetic material.

Further, in a fixing method in which a toner image formed on a recording material is heated and pressed and fixed by passing through a nip formed by a pressure member and a rotatable image heating member.
The image heating member is heated from the outermost surface by an external heating means,
The image heating member is a roller having a release layer having a thickness of 5 μm or more and 200 μm or less as an outermost layer, a heat storage layer as a lower layer, and an elastic layer as a lower layer,
The image heating member contains a heat conductive filler having a heat conductivity of 5.0 W / mK or more,
The thermally conductive filler is Al and / or Zn compound,
When the surface of the image heating member is measured by EPMA (electron beam microanalyzer), the abundance ratio of Al and / or Zn elements derived from the heat conductive filler is set to 0. 0 with respect to the total amount of elements detected by EPMA. 10 mass% or more and 3.00 mass% or less,
Heat capacity per unit area of the heat storage layer is not more than 100 J / m ² K or more 600J / m ² K,
The toner is preferably a fixing method in which the activation energy Ea (kJ / mol) obtained from the shift factor aT at that time is 110 (kJ / mol) or less in the master curve when the reference temperature is 120 ° C. .

In the fixing method, in the master curve of the toner at 120 ° C. as the reference temperature, the activation energy obtained from the shift factor aT at that time is Ea (kJ / mol), and the toner is tetrahydrofuran (THF). It is desirable that the following relational expression (1) is satisfied when A% of the THF-insoluble component derived from the binder resin component obtained by Soxhlet extraction is contained.
Ea / A ≦ 5.0 (Formula 1)

  In the fixing method, it is preferable that the molecular weight of the peak top is 15000 or more and 30000 or less in gel permeation chromatography (GPC) measurement of the THF soluble content of the toner.

  In the fixing method, the toner preferably has an average circularity of 0.950 or more.

  In the fixing method, the toner is preferably a toner obtained by polymerizing a polymerizable monomer composition in an aqueous medium.

  In the fixing method, the toner preferably contains at least a binder resin, a wax, and a magnetic material.

In addition, a charging step of charging the electrostatic latent image carrier with a charging means, an exposure step of exposing the charged electrostatic latent image carrier to form an electrostatic latent image, and developing the electrostatic latent image with toner A developing step for forming a toner image, a transfer step for transferring the toner image to a transfer material with or without an intermediate transfer member, and an image that can rotate a recording material carrying the toner image with a pressure member. Having a fixing step of fixing by heating and pressing by passing through a nip formed by a heating member;
The image heating member is heated from the outermost surface by an external heating means,
The image heating member is a roller having a release layer having a thickness of 5 μm or more and 200 μm or less as an outermost layer, a heat storage layer as a lower layer, and an elastic layer as a lower layer,
The amount of the filler having a thermal conductivity of 5.0 W / mK or more in the surface portion of the image heating member is 0.10% by mass or more and 3.00% by mass or less,
In the toner the heat capacity per unit area of the heat storage layer is applied to an image forming method is not more than 100 J / m ² K or more 600J / m ² K,
The toner is a toner characterized in that the activation energy Ea (kJ / mol) obtained from the shift factor aT at that time is 110 (kJ / mol) or less in the master curve when the reference temperature is 120 ° C. It is desirable to be.

In the master curve of the toner at 120 ° C. as the reference temperature, the activation energy obtained from the shift factor aT at that time is Ea (kJ / mol), and the toner is subjected to Soxhlet extraction with tetrahydrofuran (THF). It is desirable that the following relational expression (1) is satisfied when A% of the THF-insoluble component derived from the binder resin component is contained.
Ea / A ≦ 5.0 (Formula 1)

  Further, in gel permeation chromatography (GPC) measurement of the THF soluble content of the toner, the peak top molecular weight is desirably 15000 or more and 30000 or less.

  The average circularity of the toner is desirably 0.950 or more.

  Further, it is desirable that the toner is a toner obtained by polymerizing a polymerizable monomer composition in an aqueous medium.

  The toner preferably contains at least a binder resin, a wax, and a magnetic material.

  According to the present invention, it is possible to provide an image forming method, a fixing method, and a toner that are excellent in low-temperature fixing property, low-temperature offset resistance, and fixing tailing suppression even when a fixing member having a release layer is used.

  Hereinafter, the present invention will be described in detail.

  The present invention relates to an image forming method, a fixing method, and a toner, and includes a charging step for uniformly charging an image carrier, a latent image forming step for forming a latent image by exposing the charged image carrier, A conventionally known electrophotographic process can be applied to the developing process for developing the electrostatic latent image to form a toner image and the transferring process for transferring the developed image onto a recording material, and there is no particular limitation.

The image forming method of the present invention comprises a charging step of charging an electrostatic latent image carrier with a charging means, an exposure step of exposing the charged electrostatic latent image carrier to form an electrostatic latent image, and the electrostatic A development process for developing a latent image with toner to form a toner image, a transfer process for transferring the toner image to a recording material with or without an intermediate transfer member, and pressurizing the recording material carrying the toner image In an image forming method having a fixing step of fixing by heating and pressing by passing a nip formed by a member and a rotatable image heating member,
The image heating member is heated from the outermost surface by an external heating means,
The image heating member is a roller having a release layer having a thickness of 5 μm or more and 200 μm or less as an outermost layer, a heat storage layer as a lower layer, and an elastic layer as a lower layer,
The image heating member contains a heat conductive filler having a heat conductivity of 5.0 W / mK or more,
The thermally conductive filler is Al and / or Zn compound,
When the surface of the image heating member is measured by EPMA (electron beam microanalyzer), the abundance ratio of Al and / or Zn elements derived from the heat conductive filler is set to 0. 0 with respect to the total amount of elements detected by EPMA. 10 mass% or more and 3.00 mass% or less,
Heat capacity per unit area of the heat storage layer is not more than 100 J / m ² K or more 600J / m ² K,
The toner has an activation energy Ea (kJ / mol) calculated from a shift factor aT at that time, which is 110 (kJ / mol) or less in a master curve when 120 ° C. is a reference temperature. Is the method.

  As described above, in the external heating method, the image heating member is provided with a release layer containing a highly heat-conductive filler in the outermost layer so as not to prevent heat conduction, and a heat storage layer having a sufficient heat capacity is provided in the lower layer. In addition, it is possible to have a short first printout time and releasability by having a heat insulating layer that does not escape the heat energy stored in the lower layer.

  Further, by combining a roller having both high releasability and low-temperature fixability with a toner whose activation energy is controlled low, that is, a toner that can be deformed and fixed with low energy, the desired low-temperature fixability in the present invention can be obtained. It becomes possible to combine low-temperature offset resistance and fixing tailing.

  That is, the present invention controls the structure and properties of the fixing roller and controls the structure of the binder resin and magnetic material of the toner used, thereby improving the releasability and the low-temperature fixability, and the effects of the present invention are improved. It is what has come to obtain.

  First, the image heating member of the present invention will be described.

  The image heating member of the present invention has a three-layer structure of a release layer, a heat storage layer, and an elastic layer in order from the surface of the image heating member, and the release layer has a thickness of 5 μm to 200 μm. This release layer is an important configuration in using various media and toners in combination in order to remarkably enhance the release effect between the image heating member and the toner. However, since the thermal conductivity of the release layer is low, the amount of heat required for fixing increases due to loss when the amount of heat is applied by the heater. According to the study by the present inventors, the range of the release layer thickness capable of suppressing the loss of heat while providing high release properties was 5 μm or more and 200 μm or less. If the thickness of the release layer is less than 5 μm, the releasability between the image heating member and the toner is lowered, and problems during fixing such as low temperature offset occur. If it exceeds 200 μm, the low temperature offset is improved, but the heat capacity of the surface is lowered, so the temperature of the heater must be increased. For this reason, it is important that the thickness of the release layer is 5 μm or more and 200 μm or less, and more preferably 5 μm or more and 100 μm or less.

  In such an image heating member configuration, as a result of repeated investigations for lowering the fixing temperature, it has been important to control the physical properties and existence state of the heat conductive filler and the physical properties of the heat storage layer. In addition, the heat conductive filler of this invention contains Al and / or Zn. This is because when Al and / or Zn is contained, the filler easily obtains high thermal conductivity, and is very easy to apply to the image heating member of the present invention.

That is, in the present invention, (A) the presence ratio of Al and / or Zn elements derived from the heat conductive filler when the surface of the image heating member is measured by EPMA (electron beam microanalyzer) is detected by EPMA. It is 0.10 mass% or more and 3.00 mass% or less with respect to element amount, (B) The thermal conductivity of a heat conductive filler is 5.0 W / mK or more, (C) The heat capacity of a thermal storage layer is 100 J /. It was important to control to m ² K or more and 600 J / m ² K or less.

  First, (A) will be described. The image heating member of the present invention has a three-layer structure of a release layer, a heat storage layer, and an elastic layer. However, as described above, since there is a release layer having a low thermal conductivity, the thermal conductivity of the surface is lowered, so that the fixing temperature is raised. Then, when examination which raises the heat conductivity of a mold release layer was conducted, it discovered that fixing temperature could be lowered significantly by making a small amount of heat conductive fillers exist in the mold release layer surface. In the present invention, EPMA was used as a method for detecting the heat conductive filler on the surface of the release layer. EPMA measures an element existing at a depth of several μm from the surface, and detected Al and Zn elements correspond to the amount of thermally conductive filler existing at a depth of several μm from the surface. According to the study by the present inventors, the above effect was obtained when the ratio of Al and / or Zn detected by EPMA measurement was 0.10% by mass or more based on the total amount of elements detected. As the reason for this, the present inventors consider as follows. When the release layer receives heat from the heater, the heat reaches the heat storage layer through the release layer and is stored. At this time, since the release layer has low thermal conductivity, a heat loss is generated. Here, if there is a heat conductive filler in an amount such that the Al and / or Zn abundance ratio is 0.10% by mass or more on the surface of the release layer, the heat is efficiently supplied to the heat storage layer via the highly heat conductive filler. Communicated. Thus, it is considered that heat loss is unlikely to occur, and the image heating member can be heated to a desired temperature at the minimum necessary heater temperature.

  For this reason, the greater the amount of the heat conductive filler on the releasable surface, the higher the thermal conductivity and the greater the effect of lowering the fixing temperature. However, in general, the heat conductive filler containing Al and / or Zn has a higher affinity with the toner than the rubber forming the roller. For this reason, if a large amount is contained in the release layer, the release effect is lost and a low temperature offset occurs. According to the study by the present inventors, when the Al and / or Zn presence ratio detected by EPMA measurement is 3.00 mass% or less, the low temperature offset resistance can be satisfied while lowering the fixing temperature.

  Therefore, the surface of the image heating member is 0.10% by mass or more and 3.00% by mass with respect to the total amount of elements in which the presence ratio of Al and / or Zn elements is measured when the surface of the image heating member is measured by EPMA. The following amount of thermally conductive filler is required. If it is less than 0.10% by mass, there is not enough filler to mediate the surface and the heat storage layer, and the amount of heat received from the heater is greatly lost before being transferred to the heat storage layer, and the fixing temperature rises. On the other hand, if it exceeds 3.00% by mass, the amount of the heat conductive filler is large, so that the adhesive force between the release layer and the toner is increased, and the low temperature offset resistance is remarkably deteriorated.

  Next, the thermal conductivity of the thermal conductive filler (B) will be described. The heat conductive filler in the image heating member configuration of the present invention needs to efficiently transfer heat from the release layer surface to the heat storage layer. For this reason, it is necessary to have a high thermal conductivity. Specifically, if it is 5.0 W / mK or more, heat can be efficiently transferred to the heat storage layer even with a small amount of filler on the surface. If it is less than 5.0 W / mK, the heat loss increases with a decrease in heat transfer efficiency, and the fixing temperature increases.

  When the heat conductive filler is slightly present on the surface of the image heating member by (A) and the heat conductivity of the heat conductive filler is adjusted to be high by (B), the surface of the heat conductive filler as described in (A). And the effect of thermally mediating the heat storage layer is greatly increased. Due to the synergistic effect of (A) and (B), the image heating member can achieve both high releasability and high heat transfer efficiency between the surface and the heat storage layer, thereby improving low temperature offset resistance and lowering the fixing temperature. I can do it.

The heat capacity of the heat storage layer (C) will be described. The image heating member in the present invention comprises means for heating from the outside. Here, considering the movement of heat, the heat generated by the heater is received by the image heating member and further applied to the toner on the recording material to be fixed. However, since the heater and the recording material fixing portion are separated from each other, heat must be held in the heat storage layer until the portion heated by the heater reaches the fixing portion. Therefore, it was necessary to increase the heat capacity of the heat storage layer. Specifically, 100 J / m ² K or more was necessary. On the other hand, if the heat capacity is too large, the temperature rise on the surface of the image heating member becomes slow. Therefore, the on-demand property is inferior, and the amount of heat necessary for fixing increases. In order to eliminate such harmful effects, the heat capacity of the heat storage layer was required to be 600 J / m ² K or less. Therefore, heat of the heat storage layer is important to the 100 J / m ² K or more 600 J / m ² K or less. When the heat capacity is less than 100 J / m ² K, the amount of heat radiation increases and the recording material is easily deprived of heat. For this reason, the heat energy required by the image heating member during fixing increases. Exceeding 600 J / m ² K is not preferable because the temperature rise rate of the image heating member decreases and the warm-up time is extended, resulting in poor on-demand performance.

  As described above, in the image heating member of the present invention, it is important to adjust the amount of filler on the surface, adjust the thermal conductivity of the filler, and control the heat capacity of the heat storage layer after the image heating member has a three-layer structure. The object of the present invention can be achieved by an image heating member satisfying all of these.

  Hereinafter, preferred embodiments of the image heating member of the present invention (hereinafter also referred to as a fixing roller) will be described.

  As shown in FIG. 1, the image heating member 30 of the present invention forms an elastic layer (hereinafter, also referred to as a heat insulating elastic layer) 32 having a low thermal conductivity and elasticity on the outer periphery of a cored bar 31. A heat storage layer 33 is formed outside the heat insulating elastic layer 32, and a release layer (not shown) is further formed outside.

  The metal core 31 of the image heating member of the present invention is formed of, for example, a metal material such as aluminum, iron, or SUM material, or another rigid material such as ceramic. Since the core 31 is insulated from the surface of the fixing roller by the heat insulating elastic layer 32, it may have low thermal conductivity and low heat capacity. The form may be a hollow cylinder.

  The heat insulating elastic layer 32 formed on the outer periphery of the cored bar 31 is a rubber layer having a low thermal conductivity, and the thermal conductivity is adjusted to be smaller than that of the heat storage layer 33. In the present invention, it is preferable that the elastic layer has a thermal conductivity of 0.15 W / mK or less because the heat quantity of the heat storage layer is difficult to escape to the cored bar and there is no loss of heat quantity.

  The thickness of the heat insulating elastic layer 32 is not particularly limited, but is 1.0 mm or more and 5.0 mm or less in order to configure the fixing roller 30 having a small diameter without having an effective heat insulating property and a large heat capacity. Preferably it is 2.0 mm or more and 4.0 mm or less.

  From the viewpoint of durability and heat insulating properties, the heat-insulating elastic layer is fired after forming a compound in which a hollow filler is blended with an organopolysiloxane composition or a compound in which a water-absorbing polymer and water are blended in an organopolysiloxane composition. And what was formed by hardening is preferable.

  A method for forming the heat insulating elastic layer 32 will be exemplified below.

  For example, a silicone rubber composition, which is formed by blending 0.1 to 200.0 parts by mass of a hollow filler having an average particle size of 500 μm or less with 100 parts by mass of a thermosetting organopolysiloxane composition. A balloon rubber layer formed by heat curing the product.

  Here, as the hollow filler, there is a microballoon material or the like that reduces the thermal conductivity like sponge rubber by having a gas portion in the cured product. Examples of the microballoon material include glass balloons, silica balloons, carbon balloons, phenol balloons, acrylonitrile balloons, vinylidene chloride balloons, alumina balloons, zirconia balloons, and shirasu balloons.

  The amount of the hollow filler is 0.1 to 200.0 parts by mass, preferably 0.2 to 150.0 parts by mass, with respect to 100 parts by mass of the thermosetting organopolysiloxane composition. Hereinafter, it is more preferably 0.5 parts by mass or more and 100.0 parts by mass or less. In this case, it is preferable to blend so that the content of the hollow filler in the silicone rubber composition for a fixing roller is 10% to 80%, particularly 15% to 75% by volume. If the volume ratio is too small, the decrease in thermal conductivity tends to be insufficient, and if it is too large, molding and blending are difficult, and the molded product may be brittle without rubber elasticity.

  Alternatively, for example, the silicone rubber heat insulating layer 32 may be formed by a method of adding a water-absorbing polymer and water. Examples of the silicone rubber composition include 100 parts by mass of an organopolysiloxane composition, 0.1 to 50.0 parts by mass of a water-absorbing polymer, 10 to 200 parts by mass of water, and other platinum compound catalysts. To form a composition to which a curing catalyst such as SiH and a crosslinking agent such as SiH polymer are added. Thereafter, this may be thermoformed to form the heat insulating elastic layer 32.

  In this case, heating is performed in the following three or two stages. That is, in the first stage, the silicone base polymer is not substantially cured and does not evaporate, and is heated at 100 ° C. or less, preferably 50 ° C. or more and 80 ° C. or less for 10 hours or more and 30 hours or less. Mold molding. Next, in the second stage, the molded product is heated at 120 ° C. or more and 250 ° C. or less, preferably 120 ° C. or more and 180 ° C. or less for 1 to 5 hours, and the contained water and impurities contained in water Evaporate moisture. And in the final third stage, the obtained porous body is heated at 180 ° C. or higher and 300 ° C. or lower, preferably 200 ° C. or higher and 250 ° C. or lower for 2 to 8 hours to advance the curing, thereby achieving the desired porous property. A silicone rubber layer of a rubbery elastic body is completed.

  Therefore, it is desirable that the heat insulating elastic layer 32 is formed of a liquid silicone composition mainly composed of a balloon such as a microballoon or an organopolysiloxane containing a water-absorbing polymer. The heat insulating elastic layer thus obtained is superior in heat insulation and durability and has less thermal expansion than the sponge silicone rubber heat insulating layer or the solid rubber heat insulating layer.

  Next, the heat storage layer 33 formed on the outer periphery of the heat insulating elastic layer 32 will be described. The heat storage layer 33 is a solid rubber layer in which a layer in which a powdery heat conductive filler (hereinafter also simply referred to as “filler”) is mixed with, for example, silicone rubber or fluororubber is formed on the heat insulating elastic layer 32. It is mentioned as a suitable form. It is preferable for the heat storage layer to have the above configuration because the amount of heat applied to the heat storage layer via the release layer diffuses quickly throughout the heat storage layer.

  It is important that the thermal conductivity of the heat storage layer is higher than that of the heat insulating elastic layer 32. Preferably, the thermal conductivity is higher than that of general solid rubber, and it is desirable to set it to 0.30 W / m · K or more.

  By making the thermal conductivity of the internal heat insulating layer lower than the thermal conductivity of the heat storage layer, the heat transferred from the surface of the fixing roller is unevenly distributed in the heat storage layer near the surface, thereby making it easy to maintain. Further, by increasing the thermal conductivity of the heat storage layer, heat can be absorbed and released quickly in the heat storage layer.

  The thickness of the heat storage layer 33 is preferably 20 μm or more and 500 μm or less.

  The heat storage layer 33 in which the filler is dispersed and the heat capacity is increased has elasticity while having elasticity. For this reason, if the heat storage layer is too thick, the surface of the fixing roller becomes hard and the adhesion to the recording material is deteriorated. Therefore, it becomes difficult to perform uniform toner image fixing. For this reason, as for the thermal storage layer 33, 500 micrometers or less are desirable.

  On the other hand, if the heat storage layer is too thin, it is difficult to uniformly disperse the filler and make the heat capacity uniform, which causes uneven fixing. Therefore, the heat storage layer 33 is preferably 20 μm or more.

  The heat conductive filler used in the present invention has a heat conductivity of 5.0 W / mK or more. The shape of the filler may be any shape. In the present invention, the heat conductive filler contains Al and / or Zn. These are essential because they have high thermal conductivity and tend to lower the fixing temperature. Examples of the heat conductive filler that can be used in the present invention include powdered heat conductive fillers such as alumina, zinc oxide, aluminum nitride, zinc nitride, metal aluminum, metal zinc, an aluminum-containing alloy, and a zinc-containing alloy. .

  The amount of the heat conductive filler mixed is preferably 10% by mass or more and 50% by mass or less because the on-demand property is enhanced and heat can be easily retained. When the mixing amount of the heat conductive filler is 10% by mass or more, the heat capacity of the heat storage layer is sufficiently increased, so that the fixing temperature of the image heating member tends to be lowered. . On the other hand, when it is 50% by mass or less, the heat capacity of the heat storage layer becomes appropriate, so that the rate of temperature increase increases and the warm-up time tends to be shortened.

  Any method can be used as the method for producing the heat storage layer of the present invention. For example, methods such as dipping coating, spray coating, and ring coating in which a liquid resin is coated and formed using a cylindrical coating head around a cylindrical core metal. In particular, ring coating can be preferably used because the heat storage layer can be formed uniformly.

  FIG. 2 shows an example of a ring coating apparatus. A column 72 is vertically mounted on the gantry 71, and a precision ball screw 73 is vertically mounted on the gantry 71 and the column 72. Two linear guides 84 are attached to the column 72 in parallel with the precision ball screw 73. The LM guide 74 is connected to a linear guide 84 and a precision ball screw 73 so that a rotary motion is transmitted from a servo motor 75 via a pulley 76 so that the LM guide 74 can be raised and lowered. A ring-shaped coating head 78 for discharging the coating liquid is attached to the column 72 on the outer peripheral surface of the cylindrical core body 85. Further, a bracket 77 is mounted on the LM guide 74, and a workpiece lower holder 79 that holds and fixes the core body 85 is vertically mounted on the bracket 77, and the workpiece upper holder that holds the opposite core body 85. A central axis 80 is attached to the upper portion of the bracket 77, and the work upper holding tool is disposed so as to be concentric with the work lower holding tool 79 and holds the core body 85.

  The center axis of the ring-shaped coating head 78 is supported so as to be parallel to the moving direction of the workpiece lower holder 79 and the workpiece upper holder 80. Further, when the workpiece lower holder 79 and the workpiece upper fixture 80 are moved up and down, the center axis of the discharge port that is an annular slit opened inside the coating head 78, the workpiece lower holder 79, and the workpiece upper holder are held. The center axis of the tool 80 is adjusted to be concentric. With such a configuration, the central axis of the discharge port formed as an annular slit of the coating head 78 can be aligned with the central axis of the core body 85, and the inner peripheral surface of the ring-shaped coating head and the core body A uniform gap is formed between the outer peripheral surface of 85.

  The coating solution supply port 81 is connected to a material supply valve 83 via a coating solution conveying pipe 82. The material supply valve 83 includes a mixing mixer, a material supply pump, a material fixed amount discharge device, a material tank, and the like in front of the material supply valve 83, and can discharge a fixed amount (a constant amount per unit time) of the coating liquid.

  In order to keep the temperature in the circumferential direction constant in the process of semi-curing the unvulcanized liquid rubber formed on the outer periphery of the core body and the process of curing and bonding the semi-cured liquid rubber and the resin liquid after application lamination It is preferable to use a method of heating while rotating the rubber roller. As the heat source, a far-infrared ceramic heater, a near-infrared heater, a lamp heater, a UV heater, a micro heater, or the like that can heat the rubber roller without contact is desirable.

  A plurality of these heat sources are arranged at regular intervals in the longitudinal direction of the rubber roller in order to continuously change the heating temperature from both ends of the rubber roller toward the center. The number of heat sources is appropriately determined according to the heating temperature change pattern in the longitudinal direction of the rubber roller, but as the number increases, the temperature change in the longitudinal direction of the rubber roller can be controlled delicately and accurately. It becomes possible.

  The image heating member of the present invention forms a release layer (not shown) on the outer periphery of the heat storage layer 33. The release layer is often formed of silicone rubber, fluororubber, fluororesin or the like. In the present invention, a solid rubber layer mainly composed of fluororubber is preferable because it has high releasability from the toner and stability of the surface of the release layer. The “main component” mentioned here refers to a component occupying 70% by mass or more with respect to all components of the release layer.

  As a method for forming the release layer, any method such as dipping coating using a dispersion, spray coating, ring coating, etc. can be used as in the case of the heat storage layer. Among them, ring coating can be preferably used because the filler can be unevenly distributed in the vicinity of the surface of the heat storage layer when the release layer is formed.

  In the image heating member of the present invention, it is also important to control the roughness of the image heating member surface. Specifically, the surface roughness Rz of the image heating member is preferably 1.0 μm or more and 10.0 μm or less. When Rz is 1.0 μm or more and 10.0 μm or less, the specific surface area of the surface of the image heating member increases, and heat can be efficiently stored in the image heating member during heating from the outside. Further, since moderate unevenness exists, the releasability from the toner can be improved.

  When the Rz on the surface of the image heating member is 1.0 μm or more, the contact area between the toner and the image heating member is optimized, so that the low temperature offset tends to be improved. Further, if the Rz on the surface of the image heating member is 10.0 μm or less, the unevenness on the surface of the image heating member can be made appropriate, so that uniform and efficient heat can be applied to the toner, so that the fixing temperature can be kept low. There is a trend.

  As a method of controlling Rz, a method of mechanically polishing the surface can be mentioned. As the surface roughening method, a known polishing method such as polishing by adhering abrasive particles or abrasive particles to a tape or paper and pressing it can be used. Further, a sand blasting method in which abrasive particles are hit against the surface can be used. Among these, when polishing is performed using polishing paper, the control of Rz is easy and can be preferably used.

  The image heating member of the present invention preferably has an appropriate hardness. When the image heating member has an appropriate hardness, the releasability from the toner is enhanced. Specifically, the micro hardness of the heating member is preferably 30 ° or more and 68 ° or less. When it is 30 ° or more, the nip area can be maintained in an appropriate region even when the pressure at the fixing nip portion is set to a desired value, so that the low temperature offset tends to be improved. When the angle is 68 ° or less, the hardness of the image heating member is optimized, the fixing nip area is also optimized, and the fixing temperature tends to be lowered.

  The image heating member of the present invention preferably has a configuration capable of quickly applying heat to the recording material after receiving the amount of heat from the heater. Therefore, it is desirable that the fixing roller 30 has a small diameter, and the outer diameter is preferably in the range of 5 mm to 20 mm.

  Next, an image forming apparatus for carrying out the image forming method of the present invention will be described.

(1) Example of Image Forming Apparatus FIG. 3 is a schematic cross-sectional view showing a schematic configuration of a laser beam printer (hereinafter abbreviated as a printer) 1 as an example that suitably illustrates the image forming apparatus of the present embodiment.

  Image information is input to the printer 1 from an image information providing device (not shown) such as a host computer provided outside the printer body. The printer 1 performs a series of image forming processes in which an image corresponding to the input image information is formed and recorded on a sheet-like recording material (recording medium) P according to a known electrophotographic system.

  The printer 1 includes a process cartridge 4 that holds a drum-like rotatable electrophotographic photosensitive member (hereinafter abbreviated as a photosensitive member) 2 as a latent image carrier, a primary charging mechanism 8, and a developing device 3. I have. Further, a laser scanner unit (hereinafter abbreviated as “scanner”) 5 for forming an electrostatic latent image corresponding to the image information on the outer peripheral surface of the photoreceptor 2 by an exposure processing step corresponding to the image information input from the image information providing apparatus. It has. Further, a roll-shaped rotatable transfer body 6 that performs a process of transferring an image to the recording material P, and a fixing device 7 as an image heating apparatus that performs a fixing process on the recording material P that has undergone the image transfer process by heating and pressing. It has.

  The process cartridge 4 is detachably supported with respect to the printer body. When maintenance such as repair of the photosensitive member 2 or supply of developer to the developing device 3 is necessary, the maintenance is performed by opening the cover 9 that is supported by the main body so as to be freely opened and closed and then replacing the process cartridge 4 together. Speeding up and simplification.

  The primary charging mechanism 8 is configured to charge the outer peripheral surface of the rotating photosensitive member 2 to a specified potential distribution by applying a specified bias before the exposure processing step by the scanner 5.

  The scanner 5 outputs a laser La corresponding to the image information from the image information providing apparatus. The laser La scans and exposes the charged outer peripheral surface of the photoreceptor 2 through a window 4a provided in the process cartridge body. As a result, an electrostatic latent image corresponding to the image information is formed on the outer peripheral surface of the photoreceptor 2.

  Next, a series of image forming processes in the printer 1 will be described. When the start button or the like (not shown) provided on the printer main body is pressed, the rotation of the photosensitive member 2 is started. The photoreceptor 2 is driven to rotate at a specified peripheral speed in the clockwise direction indicated by the arrow K1. At the same time, the outer peripheral surface of the photoreceptor 2 is charged to a specified potential distribution by the primary charging mechanism 8 to which a specified bias is applied.

  Next, the charged portion of the outer peripheral surface of the photoconductor 2 is scanned and exposed by the scanner 5 in accordance with image information from the image information providing apparatus. Thereby, an electrostatic latent image corresponding to the image information is formed on the portion of the photoreceptor 2. The electrostatic latent image is developed by the developer of the developing device 3 to be visualized as a toner image.

  On the other hand, the recording material P is fed from the paper feed cassette 11 by the paper feed roller 12 driven at a predetermined timing. The recording material P fed from the paper feed cassette 11 is fed to a transfer nip portion formed between the photosensitive member 2 and the transfer member 6 by a registration roller pair 12a at a predetermined control timing, and the transfer nip portion. Is being nipped and conveyed. In this nipping and conveying process, the toner image on the photosensitive member 2 side is sequentially transferred to the recording material P side by the transfer member 6.

  The recording material P that has been subjected to the transfer process is subjected to heat fixing processing of the toner image by the fixing device 7 and then passes through the fixing paper discharge unit 10 that is rotatably supported by the printer main body. 13 is discharged outside the apparatus. The discharged recording material P is stacked on a tray 14 attached to the upper surface of the printer main body. As described above, a series of image forming processes is completed.

(2) Fixing device 7
FIG. 4 is a schematic cross-sectional view of a fixing device 7 which is an image heating device of an external heating system as an example that suitably illustrates the present embodiment.

  Reference numeral 30 denotes a fixing roller (fixing rotating body) as a rotatable heating member that heats an image on the recording material at the nip portion. Reference numeral 63 denotes a rotatable pressure roller as a pressure member. The pressing member 63 may be a fixed pad.

  The fixing roller 30 and the pressure roller 63 are arranged substantially in parallel in the vertical direction, and are pressed against each other by a pressure spring (not shown) at the end. Thus, a fixing nip portion (pressure nip portion) Nt having a predetermined width is formed between them in the recording material conveyance direction.

  The fixing roller 30 is rotationally driven by a driving means (not shown) in a clockwise direction indicated by an arrow at a predetermined peripheral speed. The pressure roller 63 rotates following the rotation of the fixing roller 30. Note that the fixing roller 30 and the pressure roller 63 may be separately rotated.

  Reference numeral 21 denotes a heating means (heating source) for heating the fixing roller 30 from the outside thereof. In this embodiment, the heating means 21 is a plate heater (hereinafter abbreviated as a heater). The heater 21 is fixedly held on the heater holder 24 and arranged in parallel on the upper side of the fixing roller 30. The holder 24 is pressed with a constant pressure by a pressurizing mechanism (not shown), and the heater 21 is adjusted so as to come into pressure contact with the upper surface of the fixing roller 30 with a predetermined pressure. The heater 21 is always in contact with the fixing roller 30 at the same position, and forms a heating nip portion Nh having a predetermined width in the rotational direction of the fixing roller 30 with the fixing roller 30.

  The rotating fixing roller 30 is heated from the outside by the heater 21 at the heating nip portion Nh, and is given a necessary and sufficient amount of heat to fix the unfixed toner image T on the recording material P at the fixing nip portion Nt. .

  As described above, after the toner image T is formed in the image forming portion, the recording material P is sent to the fixing device 7 and introduced into the fixing nip portion Nt formed by the fixing roller 30 and the pressure roller 63. It is nipped and conveyed. In the process in which the recording material P is nipped and conveyed through the fixing nip portion Nt, the recording material P is heated by the fixing roller 30 and receives the nip portion pressure so that the unfixed toner image T is thermally pressed as a permanently fixed image on the recording material P surface. It is fixed.

[Developer]
The inventors of the present invention have also studied the constituent materials and the manufacturing method relating to the toner, and by controlling the activation energy (Ea) value of the toner at 120 ° C. to 110 kJ / mol or less, energy-saving low-temperature fixability on paper. It has been found that the desired low-temperature fixability, low-temperature offset resistance, and reduction in fixing tailing during energy-saving fixing can be suppressed by combining with the fixing roller having high releasability according to the present invention.

  Furthermore, the present inventors have found that these activation energies are made possible by controlling the cross-linked state in the binder resin and the presence state of the binder resin and magnetic substance in the toner.

  In general, it is known that activation energy is energy necessary for a substance to transition from a ground state to a transition state. In the case of the present invention, this is considered to be energy necessary for changing the state of the toner. That is, the lower the activation energy of the toner, the easier the deformation due to heat or physical energy, and conversely, the higher the activation energy, the greater the energy required for deformation, that is, a structure that is difficult to deform.

  The activation energy obtained from the shift factor by creating the master curve at the time of measuring the frequency dispersion viscoelasticity of the toner is the activation energy at the temperature that is the reference for creating the master curve. For this reason, generally, in the case of a high reference temperature, the energy difference between the ground state and the transition state is relatively small, and the value of the activation energy tends to be small.

  Conversely, when the reference temperature is low, the difference between the energy of the ground state and the transition state becomes relatively large, so that the value of the activation energy tends to increase.

  However, in the present invention, a toner that can be quickly deformed with respect to energy such as heat and pressure can be obtained by controlling the crosslinked state of the resin structure composed of molecules in the binder resin and their continuous structure. Became possible.

  As described above, the fixing roller used in the present invention has a filler having a thermal conductivity of 5.0 W / mK or more on the surface of 0.1 to 3.0% by mass.

  That is, it is one of the factors that achieve the fixing property of the present invention by using a filler having a thermal conductivity of 5.0 W / mK or more and having a filler amount of 0.1% by mass or more and 3.0% by mass or less. It is possible to combine a certain high thermal conductivity and releasability by preventing the filler from being excessively present.

  By combining this with a toner whose activation energy is controlled to 110 kJ / mol or less, such as the toner of the present invention, it is possible to achieve low temperature fixability, fixing tailing reduction, and low temperature offset required for the present invention.

  The inventor considers this reason as follows.

  By containing a filler having a high thermal conductivity as in the present invention, the effect of efficiently transferring the heat of the external heating system to the heat storage layer and the action of transferring the stored heat to the toner are quickly performed, and further the activation energy Therefore, the toner is rapidly deformed. As described above, the heat conduction from the fixing roller to the toner and the process until the toner is deformed and fixed on the recording medium such as paper are promptly performed, resulting in insufficient fixing and low releasability. It is possible to suppress fixing tailing. Furthermore, it is possible to obtain desired low-temperature fixability and low-temperature offset resistance from a fixing system having both efficient thermal conductivity and high releasability and low energy required for toner deformation.

  When the activation energy is larger than 110 kJ / mol, it indicates that the energy required for the deformation of the toner is large, which is disadvantageous for low-temperature fixability, inferior to quick fixing to a recording medium, and easily causes fixing tailing. Become.

  A specific method for measuring the activation energy is described below.

  As the measuring device, a rotating plate type rheometer ARES (trade name, manufactured by TA INSTRUMENTS) is used.

As a measurement sample, a disk-shaped sample having a diameter of 25 mm and a thickness of 2.0 ± 0.3 mm obtained by press-molding toner with a tablet molding machine at 25 ° C. is used.
Mounted on a parallel plate and heated from room temperature (25 ° C.) to 100 ° C. over 15 minutes to adjust the shape of the disk, and then start measurement.

In particular, it is important to set the sample so that the initial normal force is 0,
As will be described below, in the subsequent measurement, the effect of the normal force can be canceled by performing automatic tension adjustment (Auto Tension Adjustment ON).

The measurement is performed under the following conditions.
1. A parallel plate with a diameter of 25 mm is used.
2. The frequency (Frequency) is 0.1 Hz (Initial) and 100 Hz (Final).
3. The applied strain initial value (Strain) is set to 0.1%.
4). The measurement is started with a start temperature of 100 ° C., an end temperature of 160 ° C., a heating step of 10 ° C., and a holding time (SOAK TIME) of 1 minute.

  In the measurement, the following automatic adjustment mode setting conditions are used.

In the measurement, an automatic tension adjustment mode (Auto Tension) is adopted.
5. Automatic tension direction (Auto Tension Direction) is set as compression (Compression).
6). The initial static force (Initial Static Force) is set to 0 g, and the automatic tension sensitivity (Auto Tension Sensitivity) is set to 10.0 g.
7). The operation condition of the automatic tension (Auto Tension) is when the sample modulus is smaller than 1.0 × 10 ⁶ (Pa).

  As a result of the storage elastic modulus G ′ measured in the range of 0.1 to 100 Hz and 100 ° C. to 160 ° C. measured as described above, a master curve can be created by the following method. In the present invention, the actual heat transfer to the toner is lower than that of the fixing device main body, and assuming that the fixing temperature on the fixing material such as continuous paper is severe, 120 ° C. is set as one reference temperature. A master curve was created. As for the shifting method, TWO Dimensional Minimization is selected to optimize by shifting the length and breadth, and the calculation method is selected as Guess Mode so that the gradient of the shift factor is given priority. Further, the activation energy can be calculated from an Arrhenius plot in which the logarithm of the shift factor aT obtained when creating the master curve is plotted on the vertical axis and the reciprocal of the measured temperature T at that time is plotted on the horizontal axis.

  In addition, the toner of the present invention increases the deformability of the toner by setting the activation energy to 110 kJ / mol or less, and in combination with the thermal conductivity of the fixing roller of the present invention, a quick heat transfer system is constructed to achieve the desired fixing. Performance can be obtained. When the THF insoluble content derived from the binder resin component when subjected to Soxhlet extraction with tetrahydrofuran (THF) is defined as A%, Ea / A ≦ 5.0, more preferably Ea / A ≦ 4.0, still more preferably It is important to satisfy Ea / A ≦ 3.0. By appropriately controlling the ratio between the gel amount and the activation energy, it becomes possible to achieve both fixing properties and high release properties.

  In general, the THF-insoluble matter, which is a resin crosslinking component, becomes a factor that gives elasticity to the toner. Therefore, it is essential to contain an appropriate amount for the toner releasability.

  On the other hand, the THF-insoluble matter having such elasticity tends to be disadvantageous in the fixability where it is important to lower the melt viscosity.

  In the present invention, by controlling the structure of the THF-insoluble matter, Ea / A ≦ 5.0 is set, and a toner having a low activation energy is designed while maintaining the amount of THF-insoluble matter for maintaining elasticity to some extent. In other words, in the toner resin design, it is possible to achieve both releasability due to elasticity of THF-insoluble matter and fixing property due to high deformability.

  When Ea / A is greater than 5.0, the activation energy is high, indicating that the THF insoluble matter is small. This is the case when the absolute amount of THF insoluble matter is small, or the THF insoluble matter is very dense, hard, and elastic. Happens if the is too high. If the absolute amount of THF-insoluble matter is small, it is disadvantageous for high-temperature offset resistance and storage stability. If the THF-insoluble matter is too hard, it is advantageous for high-temperature offset resistance and releasability, but it is disadvantageous for low-temperature fixing and low-temperature offset. Thus, the desired performance balanced as the toner of the present invention cannot be obtained.

  In the present invention, it is possible to apply heat energy to the fixing member with a small amount of energy by using a fixing system by external heating, and further, a large amount of energy saving fixing, that is, low-temperature fixing by using a toner that can be deformed with a small amount of energy. An effect can be obtained. Furthermore, in addition to improving the fixability by a quick heat transfer system, as described above, the balance between the activation energy and the THF-insoluble content is controlled by optimizing the structure of the THF-insoluble content, so that the high releasability effect becomes more prominent. Therefore, it is possible to obtain fixing tail reduction and low-temperature offset resistance, which are the effects of the present invention.

  A component insoluble in THF (hereinafter referred to as a gel component in the present invention) is considered to have high elasticity because it has a high cross-linking density and forms a strong entanglement compared to the soluble component. By making a large amount of such an insoluble component present in the binder resin, it becomes possible to obtain high mold releasability, low-temperature offset resistance, and storage stability. However, normally, if a large amount of gel component is present, its high elasticity can cause adverse effects on low-temperature fixing. In the present invention, the crosslink density and entanglement are controlled in a moderate state, and the branched chain forming the crosslink is made flexible to form a soft gel having both elasticity and plasticity, and combined with the fixing roller of the present invention. Thus, it has been found that it is possible to combine fixing tailing suppression, low temperature offset resistance, and storage stability without inhibiting the low temperature fixing property.

  The present inventors consider that the points important for the formation of the soft gel in the binder resin component are summarized as follows. One is the control of the crosslinking state necessary for gel formation. In general, a polymer component that can be a gel forms a crosslink between molecules. Therefore, by increasing the distance between cross-linking points, it becomes possible to form a so-called sparse gel, and the long-chain cross-linked structure is unlikely to be strong, and is easily deformable for given energy. It is easy to become.

  In addition, the gel structure formed from the highly deformable cross-linkage with respect to the energy of the present invention becomes more prominent by having a portion different from a normal carbon chain bond in the cross-linked chain. An example of such a structure is considered to be a structure containing a functional group such as an ether bond contained in the carbon chain.

  As the crosslinking agent, a compound having two or more polymerizable double bonds is mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, and the like; Divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone and the like are used alone or as a mixture. In the present invention, since it is important to control the cross-linked structure loosely in order to form a soft gel, it is desirable to have a long distance between cross-linking points and a linear structure. In order to obtain a flexible structure in the linear structure, it is more preferable to have a functional group such as an ether group.

  The number of polymerizable double bonds is preferably 2 in order to obtain a moderately crosslinked structure.

  When the magnetic toner of the present invention is produced by a polymerization method, it is important to control the constitution and amount of the THF insoluble matter. As a preferable addition amount of the crosslinking agent used in the present invention, although depending on the kind of the crosslinking agent, it is 0.001 part by mass or more and 15 parts by mass or less, more preferably 100 parts by mass with respect to the polymerizable monomer. 0.01 parts by mass or more and 10 parts by mass or less, more preferably 0.05 parts by mass or more and 5 parts by mass or less, and particularly preferably 0.1 parts by mass or more and 2 parts by mass or less.

  In the present invention, it is desirable to control the reaction temperature in the toner reaction process in order to prevent the gel structure from becoming too tightly entangled.

  In other words, it is possible to prevent a rapid reaction by suppressing a rapid temperature rise from the initial stage of the reaction, and to suppress the formation of a short and strongly entangled molecular structure.

  Specifically, the initial reaction is preferably controlled to 40 ° C. or higher and 70 ° C. or lower, more preferably 40 ° C. or higher and 60 ° C. or lower, and still more preferably 40 ° C. or higher and 50 ° C. or lower.

  More preferably, the temperature is gradually raised to a predetermined temperature from the beginning of the reaction to 1 hour.

  This makes it possible to suppress the formation of an excessively entangled gel by slowing the reaction in the stage from the initial reaction to 1 hour when the reaction is considered to occur most actively. This is because such a flexible gel structure having a low activation energy can be controlled.

  The amount of insoluble matter in the Soxhlet extraction of THF derived from the binder resin in the toner obtained in the present invention is preferably about 5% to 50%, more preferably 10% to 45% in the binder resin. More preferably, it is 15% or more and 40% or less.

  When the THF-insoluble content is less than 5%, the structural change with respect to heat is very likely to occur, and the high releasability required in the present invention is inferior. Also, fixing member contamination and high temperature offset are likely to occur. Furthermore, the strength of the toner itself is likely to decrease, and the long-term durability of the toner under high temperature and high humidity tends to decrease, which is not preferable. If it is contained in an amount of more than 50%, the elasticity tends to be too high, so that the desired low-temperature fixability and low-temperature offset resistance are poor.

  The THF insoluble content of the binder resin component of the toner is measured as follows.

Toner particles or 1 g of toner is precisely weighed and charged into a cylindrical filter paper, and Soxhlet extracted with 200 ml of THF for 16 hours. Thereafter, the cylindrical filter paper is taken out, vacuum-dried at 40 ° C. for 20 hours, and the residue mass is measured to calculate from the following formula (4). The binder resin component of the toner is a component obtained by removing the magnetic material, the charge control agent, the release agent component, the external additive, and the pigment from the toner. In view of whether it is soluble or insoluble, the THF-insoluble matter is calculated based on the binder resin component.
THF insoluble matter (%) = (W2-W3) / (W1-W3-W4) × 100 Formula (4)
(Wl is the toner mass, W2 is the residue mass, W3 is the mass of components insoluble in THF other than the binder resin component of the toner, and W4 is the mass of components soluble in THF other than the resin component of the toner)

  Further, in gel permeation chromatography (GPC) measurement of THF soluble matter at room temperature, the molecular weight of the peak top is 15000 or more and 30000 or less, preferably 17000 or more and 27000 or less, more preferably 18000 or more and 25000 or less. It is preferable for optimally controlling the amount of soft gel and soluble components produced and combining low temperature fixability, low temperature and high temperature resistance, and storage stability.

  Further, the average circularity of the toner of the present invention is preferably 0.950 or more, more preferably 0.960 or more. This is because the pressure is uniformly applied to the toner particles during fixing, and the fixing surface uniformity is excellent. When the average circularity is less than 0.950, the pressure applied to the toner becomes non-uniform, so that it is liable to cause deterioration in image quality such as fixing tailing. It tends to cause a decrease in concentration.

  In the present invention, in order to obtain an image faithful to the latent image for improving the image quality, the weight average diameter of the toner is preferably 3 μm or more and 10 μm or less, and more preferably 4 μm or more and 9 μm or less.

  In a toner having a weight average particle size of less than 3 μm, the transfer residual toner on the photoconductor increases due to a decrease in transfer efficiency, and it becomes difficult to suppress the photoconductor scraping and toner fusion in the contact charging step. Furthermore, in addition to an increase in the entire surface area of the toner, the fluidity and agitation as a powder decrease, and it becomes difficult to uniformly charge individual toner particles, so fog and transferability tend to deteriorate, Besides shaving and fusion, it tends to cause non-uniformity in the image. When the weight average particle diameter of the magnetic toner exceeds 10 μm, the characters and line images are likely to be scattered and high resolution is difficult to obtain.

  In the magnetic toner of the present invention, the uniformity of the toner particles is important in order to obtain high image quality and uniform fixability. That is, the ratio of weight average particle diameter / number average particle diameter (D4 / D1) is preferably 1.40 or less, more preferably 1.35 or less, and still more preferably 1.30 or less. desirable. When the ratio of the weight average particle diameter / number average particle diameter is greater than 1.40, it means that there are many fine powders and coarse particles in the toner, and the uniformity of heat and pressure applied to the toner particles is inferior. Further, the charge amount distribution is widened, which is not preferable.

  When the toner is produced by the suspension polymerization method used as a preferred production method of the toner of the present invention, the particle size distribution (D4 / D1) of the toner indicates the uniformity of the treatment of the magnetic material used, the degree of hydrophobicity, It can be controlled by the amount and granulation conditions (type of dispersant, granulation method, granulation time).

  Here, the average particle size and particle size distribution of the toner can be measured by various methods such as Coulter Counter TA-II type or Coulter Multisizer (manufactured by Coulter Co.). In the present invention, Coulter Multisizer (manufactured by Coulter Co.). Are connected to an interface (manufactured by Nikka) and a PC9801 personal computer (manufactured by NEC), and a 1% NaCl aqueous solution is prepared using first grade sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used.

  For example, as a measurement method, 0.5 ml of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant to 100 ml of the electrolytic aqueous solution, and 5 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is dispersed for 2 minutes with an ultrasonic disperser, and the volume and number of toner particles of 2 μm or more are measured using the 100 μm aperture as an aperture with the Coulter Multisizer. Calculate the distribution. Then, the volume-based weight average particle diameter (D4) obtained from the volume distribution and the number-based length average particle diameter obtained from the number distribution, that is, the number average particle diameter (D1) are obtained. The same measurement was performed in the examples described later.

  When it is important to control the toner structure as in the present invention, a method for producing a toner (hereinafter referred to as a heavy polymer) obtained by directly polymerizing a polymerizable monomer system (polymerizable monomer composition) in an aqueous medium. The suspension polymerization method is particularly preferably used. Thereby, the magnetic property for obtaining the effect by the characteristic activation energy of the toner of the present invention by controlling the localization / separation between the polar and nonpolar components from the viewpoint of the affinity with the aqueous medium. The body and the binder resin can be unevenly distributed, and the resulting thermal conductivity can be improved.

  However, even if a normal magnetic material is included in the polymerized toner, dispersion is poor, and the amount of the magnetic material in the toner varies, such as a toner containing a large amount of magnetic material or a toner containing almost no magnetic material. In addition, it is difficult to control the toner configuration such as the uneven distribution of the magnetic substance and the binder resin, and not only the desired low-temperature fixing property and low-temperature offset property but also the charging characteristics of the toner particles are significantly reduced. Furthermore, due to the strong interaction between the magnetic substance and water during the production of the suspension polymerization toner, it is difficult to obtain a toner having a circularity of 0.950 or more, and the toner has a wide particle size distribution. The cause of these problems is that the magnetic substance is generally hydrophilic and therefore tends to be present on the toner surface. Also, the magnetic substance moves randomly when the aqueous medium is agitated, and the surface of the suspended particles composed of the monomer is dragged. This is considered to be caused by the fact that the shape is distorted and is difficult to be circular. In order to solve these problems, it is important to modify the surface characteristics of the magnetic material.

  Many proposals have been made regarding surface modification of magnetic materials used in polymerized toners. Various silane coupling agent treatment techniques for magnetic materials have been proposed in Japanese Patent Application Laid-Open Nos. 59-200254, 59-2000025, 59-200277, 59-224102, etc. JP-A-63-250660 discloses a technique for treating silicon element-containing magnetic particles with a silane coupling agent. However, the uniformity of hydrophobicity on the surface of the magnetic material is not sufficient, it is not possible to avoid the unification of the magnetic materials and the generation of the non-hydrophobized magnetic material, the dispersibility of the magnetic material is not sufficient, and the particle size distribution Will also be wide.

  Therefore, it is preferable that the magnetic fine particles used in the magnetic toner of the present invention are uniformly hydrophobized with a coupling agent. When hydrophobizing the surface of the magnetic material, it is very preferable to use a method in which the surface treatment is performed while hydrolyzing the coupling agent while dispersing the magnetic material to have a primary particle size in an aqueous medium. This hydrophobization treatment method is less likely to cause coalescence between the magnetic materials than the treatment in the gas phase, and the repulsive action between the magnetic materials due to the hydrophobization treatment works, and the magnetic material is surface-treated in the form of primary particles. Is done.

  The method of treating the surface of the magnetic material while hydrolyzing the coupling agent in an aqueous medium does not require the use of a coupling agent that generates a gas, such as chlorosilanes and silazanes, and further, In the phase, it is easy to combine the magnetic materials, and it becomes possible to use a high-viscosity coupling agent that has been difficult to treat well, and the hydrophobizing effect is very large.

Examples of the coupling agent that can be used in the surface treatment of the magnetic fine particles according to the present invention include a silane coupling agent and a titanium coupling agent. More preferably used is a silane coupling agent, which is represented by the general formula (formula a).
RmSiYn (Formula a)
[In the formula, R represents an alkoxy group, m represents an integer of 1 to 3, Y represents a hydrocarbon group such as an alkyl group, a vinyl group, a glycidoxy group or a nucryl group, and n represents an integer of 1 to 3. Show. However, m + n = 4. ]

  Examples of the silane coupling agent represented by the general formula (I) include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, β- (3,4 epoxy cyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, Vinyltriacetoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyl Diethoxy silane, n- butyl trimethoxysilane, isobutyl trimethoxysilane, trimethyl methoxysilane, hydroxypropyl Ritori silane, hexadecyl trimethoxy silane to n-, can be mentioned n- octadecyl trimethoxysilane.

Among these, it is more preferable to use an alkyltrialkoxysilane coupling agent represented by the following general formula (formula b).
_{C p H 2p + 1 -Si- (} OC q H 2q + 1) 3 ( formula b)
[Wherein, p represents an integer of 2 to 20, and q represents an integer of 1 to 3. ]

  When p in the above formula is smaller than 2, the hydrophobic treatment is easy, but it is difficult to sufficiently impart hydrophobicity, and it is difficult to suppress the exposure or release of the magnetic material from the toner particles. . On the other hand, when p is larger than 20, the hydrophobicity is sufficient, but the coalescence of the magnetic materials increases, and it becomes difficult to sufficiently disperse the magnetic materials in the toner, and fog and transferability tend to deteriorate. Become. In the present invention, it is possible to control the magnetic material in the vicinity of the toner surface by reducing the hydrophobicity of the magnetic material as much as possible and relatively increasing the affinity for the aqueous medium.

  On the other hand, when q is smaller than 3, the reactivity of the silane coupling agent is lowered and the hydrophobicity is not sufficiently performed. Particularly, alkyltrialkoxysilane in which p represents an integer of 2 to 20 (more preferably, an integer of 3 to 15) and q represents an integer of 1 to 3 (more preferably, an integer of 1 or 2). A coupling agent should be used. The treatment amount is 0.05 parts by mass or more and 20 parts by mass or less, preferably 0.1 parts by mass or more and 10 parts by mass or less, and the surface area of the magnetic substance with respect to 100 parts by mass of the magnetic substance. It is preferable to adjust the amount of the treatment agent according to the reactivity of the coupling agent.

  In order to sufficiently obtain the effects of the present invention, it is important that the magnetic material is unevenly distributed in the vicinity of the surface. Therefore, p in the formula is more preferably 3 to 10, and the treatment amount is 0.1 parts by mass or more and 5 masses. It is more preferable that the amount is not more than parts.

  In order to treat the coupling agent in the aqueous medium as the surface treatment of the magnetic substance, a method of stirring an appropriate amount of the magnetic substance and the coupling agent in the aqueous medium can be mentioned. Stirring is preferably carried out sufficiently using, for example, a mixer having stirring blades so that the magnetic material becomes primary particles in the aqueous medium.

  Here, the aqueous medium is a medium containing water as a main component. Specifically, water itself, water added with a small amount of a surfactant, water added with a pH adjusting agent, water added with an organic solvent can be raised as an aqueous medium. As the surfactant, a nonionic surfactant such as polyvinyl alcohol is preferable.

  The surfactant is preferably added in an amount of 0.1% to 5% by mass with respect to water. Examples of the pH adjuster include inorganic acids such as hydrochloric acid. Examples of the organic solvent include alcohols.

  In the magnetic material thus obtained, no particle aggregation is observed, and the surface of each particle is uniformly hydrophobized, so that when used as a material for polymerized toner, the uniformity of the toner particles is good. .

  Further, the magnetic material used in the magnetic toner of the present invention includes iron oxide such as triiron tetroxide, γ-iron oxide, etc., which may contain elements such as phosphorus, cobalt, nickel, copper, magnesium, manganese, aluminum, and silicon. The main component is used alone or in combination of two or more thereof.

These magnetic materials preferably have a BET specific surface area of 2 m ² / g or more and 30 m ² / g or less, more preferably 3 m ² / g or more and 28 m ² / g or less by a nitrogen adsorption method. Further, those having a Mohs hardness of 5 or more and 7 or less are preferable. The shape of the magnetic body includes a polyhedron, an octahedron, a hexahedron, a sphere, a needle, a scale, and the like, but a polyhedron, an octahedron, a hexahedron, a sphere, and the like having low anisotropy increase the image density. Is preferable. The shape of such a magnetic material can be confirmed by SEM or the like.

  The volume average particle size of the magnetic material is preferably 0.05 μm or more and 0.40 μm or less, more preferably 0.10 μm or more and 0.30 μm or less.

  When the volume average particle size is less than 0.05 μm, the decrease in blackness becomes remarkable, the coloring power as a colorant for black and white toners decreases, and the aggregation of the composite oxide particles becomes strong, so the dispersibility decreases. To do. Furthermore, if the volume average particle size of the magnetic material is smaller than 0.05 μm, the magnetic material itself is easily affected by oxidation and the like, and becomes reddish, and the resulting image is also reddish. The image quality tends to deteriorate.

  On the other hand, when the volume average particle diameter exceeds 0.40 μm, the coloring power becomes insufficient as in the case of a general colorant. In addition, particularly when used as a colorant for small-diameter toner, it is stochastically difficult to uniformly disperse the magnetic material in individual toner particles, and the dispersibility tends to be lowered, which adversely affects toner developability. Can happen.

  The volume average particle diameter of the magnetic material can be measured using a transmission electron microscope. Specifically, after sufficiently dispersing toner particles to be observed in an epoxy resin, a cured product obtained by curing for 2 days in an atmosphere at a temperature of 40 ° C. is used as a sample on a thin piece by a microtome. In an electron microscope (TEM), 100 magnetic particle diameters in the field of view are measured with a photograph with an enlargement magnification of 10,000 to 40,000 times. Then, the volume average particle diameter is calculated based on the equivalent diameter of a circle equal to the projected area of the magnetic material. The same measurement was performed in the examples described later.

  In the present invention, other colorants may be used in addition to the magnetic substance. Examples of the colorant that can be used in combination include magnetic or nonmagnetic inorganic compounds and known dyes and pigments. Specifically, for example, ferromagnetic metal particles such as cobalt and nickel, or alloys obtained by adding chromium, manganese, copper, zinc, aluminum and rare earth elements to these, particles such as hematite, titanium black, nigrosine dye / pigment , Carbon black, phthalocyanine and the like. These may also be used after treating the surface.

  The degree of hydrophobicity of the magnetic material used in the present invention is preferably 35% or more and 90% or less, more preferably 40% or more and 80% or less. The degree of hydrophobicity can be arbitrarily changed depending on the kind and amount of the treatment agent on the surface of the magnetic material. The degree of hydrophobicity indicates the hydrophobicity of the magnetic substance, and a substance having a low degree of hydrophobicity means that the hydrophilicity is high. Therefore, when a magnetic material having a low degree of hydrophobicity is used, the suspension polymerization method suitably used for producing the toner of the present invention causes the magnetic material to move to an aqueous system during granulation, resulting in a particle size distribution. As a result, the average circularity of the toner particles decreases. This occurs because a magnetic material that is insufficiently hydrophobized is likely to be exposed on the toner surface. Also, those having a low degree of hydrophobicity are not preferable because the liberation rate of iron and iron compounds is high. On the other hand, in order to make the degree of hydrophobicity 95%, it is necessary to use a large amount of a treatment agent on the surface of the magnetic material. In such a state, the magnetic materials are likely to be coalesced, and the uniformity of the treatment is impaired. Cheap.

  The degree of hydrophobicity in the present invention is measured by the following method. The degree of hydrophobicity of the magnetic material is measured by a methanol titration test. The methanol titration test is an experimental test for confirming the degree of hydrophobicity of a magnetic material having a hydrophobic surface.

  Hydrophobization degree measurement using methanol is performed as follows. 0.1 g of magnetic material is added to 50 ml of water in a 250 ml beaker. Thereafter, methanol is gradually added to the liquid and titration is performed. At this time, methanol is supplied from the bottom of the liquid and is gently stirred. The end of sedimentation of the magnetic substance is the time when the suspended matter of the magnetic substance is no longer confirmed on the liquid surface, and the degree of hydrophobicity is expressed as the volume percentage of methanol in the methanol and water mixture when the end of sedimentation is reached. . The same measurement was performed in the examples described later.

  The magnetic material used in the magnetic toner of the present invention is preferably used in an amount of 10 to 200 parts by mass with respect to 100 parts by mass of the binder resin. More preferably, 20 parts by mass or more and 180 parts by mass or less are used. If the amount is less than 10 parts by mass, the coloring power of the toner is lowered and it is difficult to suppress fogging. On the other hand, when the amount exceeds 200 parts by mass, the holding force by the magnetic force on the toner carrying member is increased and the developing property is lowered, and it is difficult not only to uniformly disperse the magnetic material into individual toner particles, but also the fixing property is lowered. Resulting in.

  Note that the content of the magnetic substance in the toner can be measured using a thermal analyzer, TGA7, manufactured by PerkinElmer. In the measurement method, the toner is heated from room temperature to 900 ° C. at a temperature rising rate of 25 ° C./min in a nitrogen atmosphere, and the weight loss from 100 ° C. to 750 ° C. is defined as the mass of the component excluding the magnetic substance from the toner. The remaining mass is defined as the amount of magnetic material.

  For example, in the case of magnetite, the magnetic material used in the magnetic toner of the present invention is produced by the following method. An aqueous solution containing ferrous hydroxide is prepared by adding an alkali such as sodium hydroxide to the ferrous salt aqueous solution in an amount equivalent to or greater than the iron component. Air was blown in while maintaining the pH of the prepared aqueous solution at pH 7 or higher (preferably pH 8 to 14), and ferrous hydroxide was oxidized while heating the aqueous solution to 70 ° C. or higher. First, a seed crystal to be a core is generated.

  Next, an aqueous solution containing about 1 equivalent of ferrous sulfate is added to the slurry-like liquid containing seed crystals based on the amount of alkali added previously. While maintaining the pH of the liquid at 6 or more and 14 or less, the ferrous hydroxide reaction is promoted while blowing air, and the magnetic iron oxide powder is grown with the seed crystal as the core. As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but the pH of the liquid is preferably not less than 6. Adjust the pH of the solution at the end of the oxidation reaction, stir well so that the magnetic iron oxide becomes primary particles, add the coupling agent, stir well, stir, filter, dry, and lightly crush after stirring By doing so, a magnetically treated magnetic iron oxide powder can be obtained. Alternatively, after the oxidation reaction is completed, the iron oxide powder obtained by washing and filtering is redispersed in another aqueous medium without drying, and then the pH of the redispersion is adjusted and sufficiently stirred. A silane coupling agent may be added to perform the coupling treatment.

  As the ferrous salt, iron sulfate generally produced as a by-product in the production of sulfuric acid titanium, iron sulfate produced as a by-product with the surface cleaning of the steel sheet can be used, and iron chloride or the like can be used. In general, a method for producing magnetic iron oxide by an aqueous solution method uses an iron concentration of 0.5 mol / l or more and 2 mol / l or less from the viewpoint of preventing an increase in viscosity during the reaction and the solubility of iron sulfate. Generally, the lower the iron sulfate concentration, the finer the particle size of the product. Further, in the reaction, the larger the amount of air and the lower the reaction temperature, the easier the atomization.

  By using the magnetic toner made of the hydrophobic magnetic material produced as described above, stable toner charging property can be obtained, transfer efficiency is high, and high image quality and high stability are possible.

The magnetic toner of the present invention is a magnetic toner having a toner magnetization value of 10 Am ² / kg (emu / g) to 50 Am ² / kg (emu / g) in a magnetic field of 79.6 kA / m (1000 oersted). It is preferable. This is because magnetic toner can be prevented from leaking with magnetic toner by providing magnetic force generating means in the developing device, and not only the toner transportability or stirrability can be improved, but also magnetic force acts on the magnetic toner carrier. By providing the magnetic force generating means as described above, the recoverability of the transfer residual toner is further improved, and it becomes easy to prevent the toner from being scattered because the magnetic toner forms a spike. However, if the magnetization value of the toner at a magnetic field of 79.6 kA / m is less than 10 Am ² / kg, the above effect cannot be obtained, and if the magnetic force is applied to the toner carrier, the toner spikes become unstable. In addition, image defects such as fogging, uneven image density, and poor recovery of transfer residual toner due to inability to uniformly charge toner are likely to occur. On the other hand, when the magnetic strength of the toner at a magnetic field of 79.6 kAm is larger than 50 Am ² / kg, when the magnetic force is applied to the toner, the fluidity of the toner is remarkably lowered due to magnetic agglomeration, and the developability is lowered to damage the toner. Susceptible to deterioration.

  Further, due to the magnetic aggregation of the toner, the durability under high temperature and high humidity is inferior. Further, transferability is lowered, and untransferred toner increases.

  The magnetization intensity (saturation magnetization) of the toner can be arbitrarily changed by the amount of the magnetic substance contained and the saturation magnetization of the magnetic substance.

The saturation magnetization of the magnetic material is preferably 30 m ² / kg or more and 120 Am ² / kg or less at a magnetic field of 796 kA / m.

  In the present invention, the strength of saturation magnetization of the magnetic toner is measured using an oscillating magnetometer VSM P-1-10 (manufactured by Toei Kogyo Co., Ltd.) at a room temperature of 25 ° C. and an external magnetic field of 79.6 kA / m. . Further, the magnetic properties of the magnetic material can also be measured with an external magnetic field of 796 kA / m at room temperature of 25 ° C. using a vibration magnetometer VSM P-1-10 (manufactured by Toei Kogyo Co., Ltd.).

  Further, the toner according to the present invention can be obtained by using a disk or a multi-fluid nozzle described in JP-B-56-13945 to atomize the molten mixture into the air to obtain a spherical toner, or to be soluble in the monomer. The emulsion polymerization method represented by the dispersion polymerization method that directly produces toner using an aqueous organic solvent in which the polymer is insoluble or the soap-free polymerization method that directly polymerizes in the presence of a water-soluble polar polymerization initiator to produce the toner The toner can also be manufactured by a method of manufacturing.

  Further, the magnetic toner of the present invention contains a release agent for improving the fixability, but it is preferable to contain 1% by mass or more and 30% by mass or less with respect to the binder resin. More preferably, it is 3 mass% or more and 25 mass% or less. When the content of the release agent is less than 1% by mass, the effect of adding the release agent is reduced, and further, the offset suppressing effect is also reduced. On the other hand, if it exceeds 30% by mass, the long-term storage stability is lowered, leading to deterioration of the fluidity of the magnetic toner and deterioration of image characteristics. Further, exudation of the release agent component is likely to occur, and the durability particularly under high temperature and high humidity is lowered. Further, since a large amount of wax as a release agent is included, the toner shape tends to become distorted.

  Release agents usable for the magnetic toner according to the present invention include petroleum waxes such as paraffin wax, microcrystalline wax, petrolactam and derivatives thereof, montan wax and derivatives thereof, hydrocarbon wax by the Fischer-Tropsch method and Derivatives, polyolefin waxes typified by polyethylene and derivatives thereof, natural waxes and derivatives thereof such as carnauba wax, candelilla wax, etc. The derivatives include oxides, block copolymers with vinyl monomers, and graft modified products. . Furthermore, fatty acids such as higher aliphatic alcohols, stearic acid and palmitic acid, or compounds thereof, acid amide waxes, ester waxes, ketones, hydrogenated castor oil and derivatives thereof, plant waxes, animal waxes and the like can also be used.

  Among these release agent components, those having an endothermic peak by differential thermal analysis of 40 ° C. or more and 110 ° C. or less are preferable.

  That is, the DSC curve measured with a differential differential calorimeter preferably has a maximum endothermic peak in the region of 40 ° C. or higher and 110 ° C. or lower when the temperature is raised, and more preferably in the region of 45 ° C. or higher and 90 ° C. or lower. preferable. By having a maximum endothermic peak in the above temperature range, effects on low-temperature fixing, releasability, and storage stability can be obtained. When the maximum endothermic peak is less than 40 ° C., the high-temperature offset resistance is deteriorated and the fixing member is likely to be contaminated. On the other hand, if the maximum endothermic peak exceeds 110 ° C., the fixing temperature range shifts to the high temperature side, and low temperature offset tends to occur, which is not preferable. Further, when granulation / polymerization is performed in an aqueous medium and a toner is obtained directly by the polymerization method, if the maximum endothermic peak temperature is high, a problem such as precipitation of a release agent component mainly occurs during granulation. Dispersibility of the mold is deteriorated, which is not preferable.

  The endothermic amount of the release agent and the maximum endothermic peak temperature are measured according to “ASTM D 3418-8”. For the measurement, for example, DSC7 manufactured by Perkin Elmer is used. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of heat uses the heat of fusion of indium. An aluminum pan is used as a measurement sample, and an empty pan is set as a control. The sample is heated up to 200 ° C. once to remove the heat history, then rapidly cooled, and again at a heating rate of 10 ° C./min. DSC curve measured when the temperature is raised in the range of 30 ° C. to 200 ° C. is used. The same measurement was performed in the examples described later.

  In addition, what is necessary is just to perform the measurement of the molecular weight of the resin component soluble in THF by GPC as follows.

A solution obtained by allowing the toner to stand in THF at room temperature for 24 hours and dissolving it is filtered through a solvent-resistant membrane filter having a pore diameter of 0.2 μm to obtain a sample solution, and measurement is performed under the following conditions. In addition, sample preparation adjusts the quantity of THF so that the density | concentration of the component soluble in THF may be 0.4 mass% or more and 0.6 mass% or less.
Equipment: High-speed GPC HLC8120 GPC (manufactured by Tosoh Corporation)
Column: Seven series of Shodex KF-801, 802, 803, 804, 805, 806, 807 (manufactured by Showa Denko KK)
Eluent: THF
Flow rate: 1.0 ml / min
Oven temperature: 40.0 ° C
Sample injection amount = 0.10 ml

  In calculating the molecular weight of the sample, standard polystyrene resin (TSK standard polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, manufactured by Tosoh Corporation) F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500) are used.

  In addition, the magnetic toner of the present invention may contain a charge control agent in order to stabilize the charge characteristics. As the charge control agent, a known one can be used, and a charge control agent that has a high charging speed and can stably maintain a constant charge amount is particularly preferable. Furthermore, when the magnetic toner particles are produced using a direct polymerization method, a charge control agent having a low polymerization inhibitory property and substantially free from a solubilized product in an aqueous dispersion medium is particularly preferable. Specific compounds include, as negative charge control agents, metal compounds of aromatic carboxylic acids such as salicylic acid, alkylsalicylic acid, dialkylsalicylic acid, naphthoic acid, dicarboxylic acid, metal salts or metal complexes of azo dyes or azo pigments, sulfones Examples thereof include a polymer compound having an acid or carboxylic acid group in the side chain, a boron compound, a urea compound, a silicon compound, and a calixarene. Examples of the positive charge control agent include a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, a nigrosine compound, and an imidazole compound.

  As a method of incorporating the charge control agent into the toner, there are a method of adding it inside the toner particles and a method of adding it externally. The amount of use of these charge control agents is determined by the toner production method including the type of binder resin, the presence or absence of other additives, and the dispersion method, and is not uniquely limited. When added internally, it is preferably used in the range of 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the binder resin. Further, when externally added, the amount is preferably 0.005 parts by mass or more and 1.0 parts by mass or less, more preferably 0.01 parts by mass or more and 0.3 parts by mass or less with respect to 100 parts by mass of the toner.

  However, in the magnetic toner of the present invention, it is not essential to add a charge control agent, and the toner does not necessarily contain a charge control agent by actively utilizing frictional charging with the toner layer pressure regulating member or the toner carrier. There is no need.

  Next, a method for producing a polymerized toner according to the present invention by suspension polymerization will be described. The polymerized toner according to the present invention is generally a toner, that is, a toner such as a magnetic substance, a release agent, a plasticizer, a charge control agent, a cross-linking agent, and optionally a colorant in a polymerizable monomer that becomes a binder resin. As necessary components and other additives such as polymer polymers, dispersants, etc. are added as appropriate, and the polymerizable monomer system uniformly dissolved or dispersed by a disperser, etc. contains a dispersion stabilizer And suspended in an aqueous medium.

  In the production of the polymerized toner according to the present invention, examples of the polymerizable monomer constituting the polymerizable monomer system include the following.

  Examples of the polymerizable monomer include styrene monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, and p-ethylstyrene, methyl acrylate, ethyl acrylate, acrylic Acrylic esters such as n-butyl acid, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, and phenyl acrylate , Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, Methacrylic acid dimethyl aminoethyl, methacrylic acid esters other acrylonitrile such as diethylaminoethyl methacrylate, methacrylonitrile, and the like monomers acrylamide. These monomers can be used alone or in combination. Of the above monomers, styrene or a styrene derivative is preferably used alone or mixed with other monomers from the viewpoint of the development characteristics and durability of the toner.

  In the production of the polymerized toner according to the present invention, the polymerization may be performed by adding a resin to the polymerizable monomer composition. For example, it contains hydrophilic functional groups such as amino groups, carboxylic acid groups, hydroxyl groups, sulfonic acid groups, glycidyl groups, and nitrile groups that cannot be used because monomers are water-soluble and dissolve in aqueous suspension to cause emulsion polymerization. When it is desired to introduce the polymerizable monomer component into the toner, a random copolymer of these and a vinyl compound such as styrene or ethylene, a block copolymer, or a graft copolymer, and the like, Alternatively, it is preferably used in the form of a polycondensation polyether such as polyester or polyamide, or a polyaddition polymer such as polyimine. When such a polymer containing a polar functional group is allowed to coexist in the toner, the above-described wax component is phase-separated, and the encapsulation becomes stronger, and magnetic toner particles having good blocking resistance and developability are obtained. be able to.

  Among these resins, the effect is greatly increased by containing a polyester resin. I think this is because of the following reasons. Since the polyester resin contains many ester bonds which are functional groups having relatively high polarity, the polarity of the resin itself is increased. Due to its polarity, in the aqueous dispersion medium, there is a strong tendency for the polyester to be unevenly distributed on the surface of the droplets of the polymerizable monomer composition, and polymerization proceeds while maintaining this state, resulting in toner particles. For this reason, the polyester resin is unevenly distributed on the toner surface, resulting in a uniform surface state and surface composition. As a result, the electrification becomes uniform and the inclusion property of the release agent is good. Very good developability can be obtained.

  The polyester resin used in the present invention is, for example, a saturated polyester resin, an unsaturated polyester resin, or both are appropriately selected and used for controlling physical properties such as charging property, durability, and fixing property of the toner. Is possible.

  As the polyester resin used in the present invention, a normal resin composed of an alcohol component and an acid component can be used, and both components are exemplified below.

  Examples of alcohol components include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, and 1,6 hexane. Diol, neopentyl glycol, 2-ethyl-1,3-hexanediol, cyclohexanedimethanol, butenediol, octenediol, cyclohexenedimethanol, hydrogenated bisphenol A, and bisphenol derivatives represented by formula (formula c);

〔式中、Ｒはエチレンまたはプロピレン基を示し、ｘ及びｙはそれぞれ１以上の数であり、かつｘ＋ｙの平均値は２乃至１０である。〕

[Wherein, R represents an ethylene or propylene group, x and y are each a number of 1 or more, and the average value of x + y is 2 to 10. ]

  As the divalent carboxylic acid, benzene dicarboxylic acid such as phthalic acid, terephthalic acid, isophthalic acid, phthalic anhydride or the anhydride thereof; alkyl dicarboxylic acid such as succinic acid, adipic acid, sebacic acid, azelaic acid or the anhydride, Further, succinic acid or anhydride thereof substituted with an alkyl group having 6 to 18 hydrocarbons or an alkenyl group having 6 to 18 carbon atoms; an unsaturated dicarboxylic acid such as fumaric acid, maleic acid, citraconic acid or itaconic acid, or anhydride thereof. Such as things.

  In addition, polyhydric alcohols such as glycerin, pentaerythritol, sorbit, sorbitan, and oxyalkylene ethers of novolac type phenol resins can be cited as the alcohol component, and trimellitic acid, pyromellitic acid, 1,2,3,4- Examples thereof include polyvalent carboxylic acids such as butanetetracarboxylic acid, benzophenonetetracarboxylic acid and anhydrides thereof.

  Among the polyester resins, the alkylene oxide adduct of bisphenol A, which is excellent in charging characteristics and environmental stability and balanced in other electrophotographic characteristics, is preferably used. In the case of this compound, the average added mole number of alkylene oxide is preferably 2 to 10 in terms of fixing property and toner durability.

  It is preferable that 45 mol% or more and 55 mol% or less of the polyester resin in the present invention is an alcohol component, and 55 mol% or more and 45 mol% or less is an acid component.

  The polyester resin is present on the surface of the toner particles in the method for producing a magnetic toner of the present invention, and in order for the obtained toner particles to exhibit stable chargeability, an acid of 0.1 KOH / resin 1 g or more and 50 mg KOH / resin 1 g or less is used. It is preferable to have a valence. If it is less than 0.1 mg KOH / resin 1 g, the amount existing on the toner surface is absolutely insufficient, and if it exceeds 50 mg KOH / resin 1 g, the chargeability of the toner tends to be adversely affected. Furthermore, in the present invention, an acid value range of 5 KOH / resin 1 g or more and 35 mg KOH / resin 1 g or less is more preferable.

  In the present invention, two or more kinds of polyester resins are used in combination as long as the physical properties of the obtained magnetic toner particles are not adversely affected, or modified with, for example, a silicone compound or a fluoroalkyl group-containing compound. Preparation is also preferably performed.

  Moreover, when using the high molecular polymer containing such a polar functional group, the average molecular weight is preferably 5,000 or more. When the average molecular weight is less than 5,000, especially 4,000 or less, the low molecular weight component of the high molecular weight polymer is likely to concentrate near the surface of the toner particles, which is liable to adversely affect developability, blocking resistance, etc. Absent.

  Further, a resin other than those described above may be added to the monomer composition for the purpose of improving the dispersibility and fixing properties of the material, or image characteristics. Examples of the resin used include polystyrene and polyvinyltoluene. Styrene and its substituted homopolymers: styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer Polymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer , Styrene-butyl methacrylate copolymer, styrene-dimethyl methacrylate Ethyl copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid Styrene copolymers such as copolymers, styrene-maleic acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, silicone resin, polyester resin, polyamide resin, epoxy resin Polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin and the like can be used alone or in combination. As addition amount of these resin, it is preferable to add 1 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer. If the amount is less than 1 part by mass, the effect of addition is small, while if it is added in an amount of 20 parts by mass or more, various physical properties of the polymerized toner tend to be difficult to design.

  Furthermore, if a polymer having a molecular weight different from the molecular weight range of the toner obtained by polymerizing the polymerizable monomer is dissolved in the monomer and polymerized, a toner having a wide molecular weight distribution and high offset resistance can be obtained. I can do it.

  The polymerization initiator used in the production of the polymerized toner related to the magnetic toner of the present invention has a half-life of 0.5 to 30 hours during the polymerization reaction, and 0.5 parts by mass relative to the polymerizable monomer. When the polymerization reaction is carried out in an addition amount of 20 parts by mass or less, a polymer in which the peak top of the main peak in GPC exists between 15000 and 30000 in molecular weight can be obtained.

  Examples of the polymerization initiator used in the present invention include conventionally known azo polymerization initiators and peroxide polymerization initiators. As the azo polymerization initiator, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile) ), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile and the like, and examples of peroxide polymerization initiators include t-butyl peroxyacetate, t- Butyl peroxylaurate, t-butyl peroxypivalate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxyisobutyrate, t-butyl peroxyneodecanoate, t-hexyl per Oxyacetate, t-hexylperoxylaurate, t-hexylperoxypivalate, t-hexylperoxy-2-ethyl Xanoate, t-hexylperoxyisobutyrate, t-hexylperoxyneodecanoate, t-butylperoxybenzoate, α, α'-bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecano 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylper Oxyneodecanoate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylper Oxyisopropyl monocarbonate, t-butyl peroxyisopropyl monocar Nate, t-butylperoxy 2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxy-m-toluoylbenzoate, Bis (t-butylperoxy) isophthalate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, 2,5-dimethyl-2,5-bis (m -Toluoyl peroxide) Peroxyesters such as hexane, diacyl peroxides such as benzoyl peroxide, lauroyl peroxide, isobutyryl peroxide, diisopropyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate Such as -Oxydicarbonate, 1,1-di-t-butylperoxycyclohexane, 1,1-di-t-hexylperoxycyclohexane, 1,1-di-t-butylperoxy-3,3,5-trimethyl Peroxyketals such as cyclohexane and 2,2-di-t-butylperoxybutane, dialkyl peroxides such as di-t-butyl peroxide, dicumyl peroxide and t-butylcumyl peroxide, and t-butyl as others Examples include peroxyallyl monocarbonate. If necessary, two or more of these initiators can be used.

  In the method for producing the magnetic toner of the present invention by a polymerization method, generally a composition containing at least the above-mentioned magnetic substance, polymerizable monomer, and release agent is appropriately added, and a homogenizer, ball mill, colloid mill, ultrasonic disperser is added. A polymerizable monomer composition uniformly dissolved or dispersed by a dispersing machine such as the like is suspended in an aqueous medium containing a dispersion stabilizer. At this time, the particle size of the obtained toner particles becomes sharper by using a high-speed disperser such as a high-speed stirrer or an ultrasonic disperser to obtain a desired toner particle size at a stretch.

  The polymerization initiator may be added at the same time when other additives are added to the polymerizable monomer, or may be mixed immediately before being suspended in the aqueous medium. In addition, a polymerization initiator dissolved in a polymerizable monomer or solvent can be added immediately after granulation and before starting the polymerization reaction.

  After granulation, stirring may be performed using a normal stirrer to such an extent that the particle state is maintained and particle floating and sedimentation are prevented.

  When the magnetic toner of the present invention is produced by a polymerization method, a known surfactant, organic dispersant or inorganic dispersant can be used as a dispersion stabilizer. In particular, inorganic dispersants are less likely to produce harmful ultrafine powders, and because of their steric hindrance, dispersion stability is obtained, so even if the reaction temperature is changed, stability is not easily lost, and washing is easy and does not adversely affect the toner. Therefore, it can be preferably used. Examples of such inorganic dispersants include polyvalent metal phosphates such as calcium phosphate, magnesium phosphate, aluminum phosphate and zinc phosphate, carbonates such as calcium carbonate and magnesium carbonate, calcium metasuccinate, calcium sulfate and barium sulfate. Inorganic oxides such as inorganic salts, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, silica, bentonite and alumina can be mentioned.

  When these inorganic dispersants are used, they may be used as they are, but in order to obtain finer particles, the inorganic dispersant particles can be generated and used in an aqueous medium. For example, in the case of calcium phosphate, a sodium phosphate aqueous solution and a calcium chloride aqueous solution can be mixed with high-speed stirring to produce water-insoluble calcium phosphate, which enables more uniform and fine dispersion. At the same time, a water-soluble sodium chloride salt is produced as a by-product. However, if a water-soluble salt is present in the aqueous medium, dissolution of the polymerizable monomer in water is suppressed, and an ultrafine toner based on emulsion polymerization is produced. Since it becomes difficult to generate | occur | produce, it is more convenient. Since it becomes an obstacle when removing the remaining polymerizable monomer at the end of the polymerization reaction, it is better to replace the aqueous medium or desalinate with an ion exchange resin. The inorganic dispersant can be almost completely removed by dissolving with an acid or alkali after completion of the polymerization.

  These inorganic dispersants are preferably used alone in an amount of 0.2 parts by mass or more and 20 parts by mass or less based on 100 parts by mass of the polymerizable monomer. Since the atomization is slightly weak, 0.001 part by mass or more and 0.1 part by mass or less of a surfactant may be used in combination.

  Examples of the surfactant include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, sodium stearate, potassium stearate and the like.

  In the polymerization step, the polymerization is performed at a polymerization temperature set to 40 ° C. or higher. When the polymerization is carried out in this temperature range, the release agent or wax to be sealed inside is precipitated by phase separation, and the encapsulation becomes more complete. In order to consume the remaining polymerizable monomer, it is possible to raise the reaction temperature to 90 ° C. or more and 150 ° C. or less at the end of the polymerization reaction.

  The polymerized toner particles are filtered, washed and dried by a known method after the polymerization is completed, and the magnetic toner of the present invention can be obtained by mixing inorganic fine powders if necessary and adhering them to the surface. Moreover, it is one of the desirable forms of this invention to put a classification process in a manufacturing process and to cut coarse powder and fine powder.

  In the present invention, the toner is preferably added with an inorganic fine powder having a number average primary particle size of 4 nm to 80 nm as a fluidizing agent. The inorganic fine powder is added to improve the fluidity of the toner and to make the charge of the toner particles uniform. However, adjustment of the charge amount of the toner, improvement of environmental stability, etc. by treatment such as hydrophobizing the inorganic fine powder. It is also a preferable form to provide the function.

  When the number average primary particle size of the inorganic fine powder is larger than 80 nm, or when no inorganic fine powder of 80 nm or less is added, when the transfer residual toner adheres to the charging member, it easily adheres to the charging member. Therefore, it is difficult to stably obtain good charging characteristics. In addition, good toner fluidity cannot be obtained, charging to toner particles is likely to be uneven, and problems such as increased fog, decreased image density, and toner scattering are likely to occur. When the number average primary particle size of the inorganic fine powder is smaller than 4 nm, the cohesiveness of the inorganic fine powder is increased, and the particle size distribution is wide and has strong cohesiveness that is difficult to break even by crushing treatment instead of the primary particles. It tends to behave as an agglomerate and easily causes image defects such as development of the agglomerate and damage to the image carrier or magnetic toner carrier. In order to make the charge distribution of the toner particles more uniform, the number average primary particle size of the inorganic fine powder is more preferably 6 nm or more and 35 nm or less.

  In the present invention, the method of measuring the number average primary particle size of the inorganic fine powder is a photograph of the toner magnified by a scanning electronic forehead mirror, and further by an elemental analysis means such as XMA attached to the scanning electron microscope. While contrasting the photograph of the toner mapped with the elements contained in the inorganic fine powder, 100 or more primary particles of the inorganic fine powder present on the toner surface adhering to or separating from the toner surface were measured, and the average of the number basis was 1 It can be measured by determining the secondary particle size and the number average primary radius.

As the inorganic fine powder used in the present invention, silica fine powder, titanium oxide fine powder, alumina fine powder and the like can be used, and they may be used alone or in combination. As the silica, for example, both a so-called dry method produced by vapor phase oxidation of silicon halide or dry silica called fumed silica, and so-called wet silica produced from water glass or the like can be used. Further, dry silica having less silanol groups on the surface and inside of the silica fine powder and less production residue such as Na ₂ O and SO ₃ ^2- is preferred. In dry silica, it is also possible to obtain composite fine powders of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds in the production process. Is also included.

  The addition amount of the inorganic fine powder having a number average primary particle size of 4 nm or more and 80 nm or less is preferably 0.1% by mass or more and 3.0% by mass or less with respect to the toner particles, and the addition amount is 0.1% by mass. If it is less than%, it is difficult to exhibit the effect, and if it exceeds 3.0% by mass, it is likely to be liberated and easily causes development member contamination.

  The content of the inorganic fine powder can be quantified using a calibration curve prepared from a standard sample using fluorescent X-ray analysis.

  In the present invention, the inorganic fine powder is preferably a hydrophobized product in view of characteristics in a high temperature and high humidity environment. When the inorganic fine powder added to the toner absorbs moisture, the charge amount of the toner particles is remarkably reduced, and the toner is easily scattered.

  As the treating agent used for the hydrophobizing treatment, treating agents such as silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane compounds, silane coupling agents, other organosilicon compounds, organotitanium compounds or the like alone or You may process together.

  Among them, those treated with silicone oil are preferable, and more preferably, the inorganic particles are hydrophobized with a silane compound, or are treated with silicone oil and then treated with silicone oil, even in a high humidity environment. Is more preferable in order to keep the toner high and prevent toner scattering.

  As a method for treating such inorganic fine powder, for example, as a first-stage reaction, a silanization reaction is performed with a silane compound and silanol groups are eliminated by chemical bonding, and then a hydrophobic reaction is performed on the surface with silicone oil as a second-stage reaction. The thin film can be formed.

The silicone oil may have a viscosity less of 10 mm ² / s or more 200,000 mm ² / s at 25 ° C., and more preferably the following 3,000 mm ² / s or more 80,000mm ² / s. If it is less than 10 mm ² / S, the inorganic fine powder is not stable and the image quality tends to deteriorate due to heat and mechanical stress. If it exceeds 200,000 mm ² / s, uniform processing tends to be difficult.

  As the silicone oil used, for example, dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil, fluorine modified silicone oil and the like are particularly preferable.

  As a method for treating the inorganic fine powder with silicone oil, for example, the inorganic fine powder treated with the silane compound and the silicone oil may be directly mixed using a mixer such as a Henschel mixer, or the inorganic fine powder may be mixed with the inorganic fine powder. A method of spraying silicone oil may be used. Alternatively, after dissolving or dispersing silicone oil in an appropriate solvent, inorganic fine powder may be added and mixed to remove the solvent. A method using a sprayer is more preferable in that the formation of inorganic fine powder aggregates is relatively small.

  The treatment amount of the silicone oil is 1 to 40 parts by mass, preferably 3 to 35 parts by mass with respect to 100 parts by mass of the inorganic fine powder. If the amount of silicone oil is too small, good hydrophobicity cannot be obtained, and if it is too large, problems such as fogging tend to occur.

The inorganic fine powder used in the present invention is preferably silica, alumina, titanium oxide, or a combination thereof in order to impart good fluidity to the toner, and among them, silica is particularly preferable. Furthermore, the specific surface area of silica measured by the BET method by nitrogen adsorption is preferably 20 m ² / g or more and 350 m ² / g or less, more preferably 25 m ² / g or more and 300 m ² / g or less.

  In accordance with the BET method, the specific surface area is obtained by adsorbing nitrogen gas to the sample surface using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics) and calculating the specific surface area using the BET multipoint method.

  In the magnetic toner used in the present invention, other additives such as carbon black and graphite, such as carbon black and graphite, and metals such as copper, gold, silver, aluminum, and nickel, within a rolling range that does not substantially adversely affect the toner. Fine powder: Zinc oxide, titanium oxide, tin oxide, aluminum oxide, indium oxide, silicon oxide, magnesium oxide, barium oxide, molybdenum oxide, metal oxide such as tungsten oxide; metal such as molybdenum sulfide, cadmium sulfide, potassium titanate A compound or a composite oxide thereof can be used by adjusting the particle size and particle size distribution as required. Also, lubricant powder such as Teflon (registered trademark) powder, zinc stearate powder, polyvinylidene fluoride powder, or abrasive such as cerium oxide powder, silicon carbide powder, strontium titanate powder, or titanium oxide powder, aluminum oxide powder, etc. A small amount of anti-caking agent, anti-caking agent, and organic fine particles having opposite polarity and inorganic fine particles can also be used as a developability improver. These additives can also be used after hydrophobizing the surface.

  Further, for the purpose of improving developability, it is also possible to add a conductive inorganic oxide. Metal oxides doped with elements such as antimony and aluminum, and fine powders having a conductive material on the surface can also be used. For example, a fine powder of titanium oxide surface-treated with tin oxide / antimony, a fine powder of stannic oxide doped with antimony, or a fine powder of stannic oxide.

  Examples of commercially available tin oxide / antimony-treated conductive titanium oxide fine powders include EC-300 (Titanium Industry Co., Ltd.), ET-300, HJ-1, HI-2 (above, Ishihara Sangyo Co., Ltd.), W -P (Mitsubishi Materials Corporation).

  Examples of commercially available antimony-doped conductive tin oxide include T-1 (Mitsubishi Materials Corporation) and SN-100P (Ishihara Sangyo Co., Ltd.), and examples of commercially available stannic oxide include SH-S (Japan). Chemical Industry Co., Ltd.).

  As a method for externally adding the inorganic fine powder, the conductive fine powder and the like to the toner, the toner and the fine powder are mixed and stirred. Specific examples include mechano-fusion, I-type mill, hybridizer, turbo mill, Henschel mixer and the like, and it is particularly preferable to use a Henschel mixer from the viewpoint of preventing the generation of coarse particles.

  The magnetic toner of the present invention has excellent durability, low fog, and high transferability. Therefore, the magnetic toner can be suitably used in an image forming method using a contact charging process, and can also be used in a cleanerless image forming method. . In an image forming method including a contact charging process, reduction of magnetic toner (that is, transfer residual toner) and fog toner that are transferred to the charging process without being transferred is a key technology, but by using the magnetic toner of the present invention. It is possible to obtain an image that is superior in environmental stability and superior in the long term.

  A method for measuring each physical property of the toner in the present invention will be described in detail below.

{Measuring method}
(1) EPMA (Electron Beam Microanalyzer) Measurement of Fixing Roller Surface In the present invention, Al and / or Zn elements are measured with respect to the total amount of elements detected when the surface of the fixing roller is measured by an electron beam microanalyzer (EPMA). The existence ratio is prescribed. At this time, the Al element and the Zn element are derived from the heat conductive filler. EPMA measures elements existing to a depth of several μm from the surface, and the ratio of Al and Zn to the total amount of elements corresponds to the amount of thermally conductive filler existing at a depth of several μm from the surface. Therefore, when the abundance ratio of Al or Zn is high, it indicates that more heat conductive filler exists in the surface portion.

<Measurement conditions>
Apparatus: Electron beam microanalyzer EPMA-1610 (manufactured by Shimadzu Corporation)
Acceleration voltage: 15 kV
Irradiation current: 20 nA
Measurement time: 500msec
Beam diameter: 10 μm

(2) Thermal conductivity measurement of heat conductive filler, heat storage layer, heat insulation elastic layer and heat capacity per unit area of heat storage layer ○ Measurement of heat capacity per unit area of heat storage layer In the present invention, the heat capacity per unit area of the heat storage layer is It prescribes. Here, the surface area of the heat storage layer refers to the area of the surface of the heat storage layer that appears when all the release layers are peeled off. Therefore, the “surface area of the test piece” also represents only the area of the surface that appears when peeling as described above.

The heat capacity per unit area of the heat storage layer is obtained by the following equation.
Heat capacity per unit area of fixing roller = volume of test piece × volume heat capacity ÷ surface area of test piece, or
= Volume heat capacity x specific heat capacity x heat storage layer 33 thickness Formula (A)

  Therefore, in order to calculate the heat capacity per unit area of the heat storage layer, it is necessary to first measure the specific heat capacity and the volume heat capacity. Specific heat capacity and volumetric heat capacity were determined as follows.

  First, a test piece having a length of 5 mm and a width of 5 mm is cut out from the heat storage layer 33 of the fixing roller 30, and the test piece is measured with a dry automatic densimeter (model number AccuPyc1330, Shimadzu Corporation) to obtain a mass density.

  Next, the test piece is measured with a differential scanning calorimeter (model number DSC8240, manufactured by Rigaku Corporation) to determine the specific heat capacity.

Since the volumetric heat capacity is obtained from the following equation, it is calculated from the value obtained above.
Volumetric heat capacity = mass density x specific heat capacity

  The heat capacity per unit area of the heat storage layer was calculated by substituting the specific heat capacity and the volume heat capacity thus obtained into the formula (A).

○ Measurement of thermal conductivity of thermal conductive filler / heat storage layer / adiabatic elastic layer The thermal diffusivity is measured with a Fourier transform type thermal thermal diffusivity measuring device (model number FTC-1, manufactured by ULVAC-RIKO Co., Ltd.). When measuring a heat storage layer or a heat insulating elastic layer, measurement in the thickness direction is performed. And from the following formula | equation, the heat conductivity of the heat conductive filler and the heat conductivity of the thickness direction of a thermal storage layer or a heat insulation elastic layer are calculated | required.
Thermal conductivity = thermal diffusivity x mass density x specific heat capacity

(3) Rz measuring method on the surface of the image heating member Measurement was performed at a measuring distance of 4 mm with Surfcoder SE-3300 (manufactured by Kosaka Laboratory). The measurement locations were both end portions at a position 30 mm to 40 mm from the rubber end of the image heating member and a central portion at a position 110 mm to 120 mm from the rubber end. Measurements were made in the axial direction and the circumferential direction at each location, and the average value of the six measured values was defined as Rz.

(4) Measurement of micro hardness of image heating member The micro hardness of the image heating member is measured in a peak hold mode in a 23 ° C./55% RH environment using a micro hardness meter MD-1 type (manufactured by Kobunshi Keiki Co., Ltd.). Value. Specifically, the image heating member is placed on a metal plate, and a metal block is placed on the image heating member so that the image heating member does not roll. Press the measuring terminal accurately at the center and read the value after 5 seconds. A total of three points are measured at both ends and the center of the image heating member at a position of 30 mm or more and 40 mm or less from the rubber end of the image heating member. The average value of the measured values obtained in total of 6 points was defined as micro hardness.

(5) Measurement of Toner Average Circularity The average circularity of toner is measured using a flow type particle image measuring device “FPIA-2100 type” (manufactured by Sysmex Corporation), and is calculated using the following formula.

  Here, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the toner particle image. Define. The measurement uses the perimeter of the particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm).

  In the present invention, the circularity is an index indicating the degree of unevenness of the toner particles, and is 1.000 when the toner particles are completely spherical. The more complicated the surface shape, the smaller the circularity.

  The average circularity C, which means the average value of the circularity frequency distribution, is calculated from the following equation, where ci is the circularity (center value) at the dividing point i of the particle size distribution and m is the number of measured particles.

  Further, the circularity standard deviation SD is calculated from the following equation where the average circularity C, the circularity ci of each particle, and the number of measured particles are m.

  In addition, “FPIA-2100”, which is a measuring apparatus used in the present invention, calculates the circularity of each particle, and then calculates the average circularity and the circularity standard deviation. The degrees 0.4 to 1.0 are divided into classes equally divided every 0.01, and the average circularity and circularity standard deviation are calculated using the center value of the division points and the number of measured particles.

  As a specific measuring method, 10 ml of ion-exchanged water from which impure solids have been removed in advance is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, followed by further measurement. Add 0.02 g of sample and disperse uniformly. As a means for dispersion, an ultrasonic disperser “Tetora 150 type” (manufactured by Nikka Ki Bios Co., Ltd.) is used, and dispersion treatment is performed for 2 minutes to obtain a dispersion for measurement. In that case, it cools suitably so that the temperature of this dispersion may not be 40 degreeC or more. In order to suppress variation in circularity, the installation environment of the apparatus is controlled at 23 ° C. ± 0.5 ° C. so that the temperature inside the flow type particle image analyzer FPIA-2100 is 26 to 27 ° C. Preferably, autofocus is performed using 2 μm latex particles every 2 hours.

  To measure the circularity of the toner particles, the flow type particle image measuring device is used, and the concentration of the dispersion is readjusted so that the toner particle concentration at the time of measurement is 3000 particles / μl or more and 10,000 particles / μl. 1000 or more particles are measured. After the measurement, using this data, data having an equivalent circle diameter of less than 2 μm is cut to determine the average circularity of the toner particles.

  Furthermore, “FPIA-2100”, which is a measuring apparatus used in the present invention, improves the magnification of the processed particle image as compared with “FPIA-1000” conventionally used for calculating the shape of the toner. Furthermore, the accuracy of toner shape measurement has been improved by improving the processing resolution of the captured image (256 × 256 → 512 × 512), thereby achieving more reliable capture of fine particles. Therefore, when it is necessary to measure the shape more accurately as in the present invention, the FPIA 2100 that can obtain information on the shape more accurately is more useful.

  Hereinafter, the present invention will be described more specifically with reference to production examples and examples, but these do not limit the present invention in any way.

◎ Manufacture of fixing roller (Manufacture of heat storage layer coating liquids 1 to 4)
As a silicone rubber raw material composition, 70 parts by mass of addition-type silicone rubber (manufactured by Toray Dow Corning Silicone Co., Ltd. (trade name: DY35-561A / B)) and alumina as a filler (trade name of Showa Denko Co., Ltd. (trade name) : Alumina beads CB-A50S)) was mixed in an amount of 30 parts by mass. This was diluted with methyl ethyl ketone so as to have a solid content concentration of 10%, and kneaded to obtain a heat storage layer coating solution 1. The liquid viscosity was 3.0 × 10 ⁻² Pa · s. Further, as shown in Table 1, the filler type was selected and the blending ratio was adjusted to obtain heat storage layer coating solutions 1 to 4. “Alumina” in the table is Showa Denko Co., Ltd. alumina (trade name: Alumina Beads CB-A50S), “Zinc Oxide” is Sakai Chemical Industry Co., Ltd. zinc oxide (trade name: LPZINC-11), “Zirconia” indicates zirconia (trade name: AZI) manufactured by Aszac Co., Ltd.

(Manufacture of dispersion for release layer)
-Manufacture of release layer dispersions 1, 3 and 4 For PFA dispersion (trade name: NEOFLON AD-2CR, Daikin Industries, Ltd.), alumina (Showa Denko Co., Ltd. (trade name: Alumina beads) as a filler) CB-A50S)) was blended so that the content of PFA with respect to the solid content was 1.00% by mass to obtain a release layer dispersion 1. The same operations were carried out with the content ratios being 0.05% by mass and 3.00% by mass to prepare release layer dispersions 3 and 4. Table 2 shows the main component and filler content.

-Manufacture of Release Layer Dispersion 2 Addition-type silicone rubber (Toray Dow Corning Silicone Co., Ltd. (trade name: DY35-561A / B)) 99 parts by weight alumina as filler (Showa Denko Co., Ltd.) (Product name: Alumina Beads CB-A50S) was blended in an amount of 1 part by mass. This was diluted with methyl ethyl ketone so as to have a solid content concentration of 10% to obtain a release layer dispersion 2. Table 2 shows the main component and filler content.

(Method for manufacturing fixing roller 1)
[1] Manufacture of elastic layer 50 parts each of addition-curable liquid silicone rubber material KE1218A liquid (main agent) / B liquid (curing agent) manufactured by Shin-Etsu Chemical Co., Ltd., as a hollow filler, Microballoon F80S manufactured by Matsumoto Yushi Seiyaku (material: 3 parts by weight of acrylonitrile (softening temperature: 160 ° C. or higher and 170 ° C. or lower) and 1 part of polyethylene glycol were added, and stirring was continued for 15 minutes to obtain a silicone rubber.

  The silicone rubber obtained above was cast on a SUM metal core having an outer diameter of 8 mm, subjected to primary vulcanization at 150 ° C. for 1 hour, and then removed from the mold and taken out. Next, after secondary vulcanization at 200 ° C. for 4 hours, heat treatment was further performed at 230 ° C. for 4 hours, thereby producing a fixing roller precursor 1-1 having an elastic layer having a thickness of 2 mm. . This elastic layer was balloon rubber, and the thermal conductivity was 0.12 W / mK.

[2] Production of heat storage layer The heat storage layer coating solution 1 was applied to the fixing roller precursor 1-1 using a ring coating apparatus, and the thickness of the heat storage layer was adjusted to 150 μm. At this time, the conditions of the ring coating apparatus were a moving speed of 15 mm / s and a material discharge rate of 2100 mm3 / sec. Thereafter, it was heated for 60 minutes in a 300 ° C. hot air circulating heating furnace to obtain a fixing roller precursor 1-2 having a heat storage layer.

The thermal conductivity of the filler was 23.0 W / mK, the heat capacity per unit surface area of the heat storage layer was 250 J / m ² K, the heat conductivity of the heat storage layer was 0.32 W / mK, and the thickness of the heat storage layer was 150 μm.

[3] Production of Release Layer A PFA dispersion (trade name: NEOFLON AD-2CR, Daikin Industries, Ltd.) is applied to the fixing roller precursor 1-2 using a ring coating apparatus, and the release layer is 50 μm. It adjusted so that it might become thickness. The conditions for the ring coating apparatus were a moving speed of 15 mm / s and a material discharge rate of 2100 mm3 / sec. After drying, a release layer is formed by baking at 300 ° C. for 30 minutes, and then the surface is polished with polishing paper (polishing machine: Super Finisher made by Matsuda Seiki, polishing paper: 3M Imperial Lapping Film 30 mic silicon carbide abrasive grains The fixing roller 1 was obtained. The fixing roller 1 had an Rz of 6.0 μm, an outer diameter of 12 mm, a rubber part length of 230 mm, and an outer peripheral surface (shown as a hatched portion S in FIG. 1) of 8671 mm ² . The outline of the produced roller is as shown in Table 3. The “surface existence ratio” in the table indicates the existence ratio of Al and / or Zn with respect to the total amount of elements detected when the fixing roller is measured by EPMA. Here, Al and Zn elements are derived from the heat conductive filler.

(Method for manufacturing fixing roller 2)
By changing the silicone rubber used for the elastic layer to an addition type silicone rubber (manufactured by Toray Dow Corning Silicone Co., Ltd. (trade name: DY35-561A / B)) and adjusting the polishing after forming the release layer, the Rz is 11. A fixing roller 2 was obtained in the same manner as the fixing roller 1 except that the thickness was 0 μm. The thermal conductivity of the elastic layer was 0.25 W / mK. The outline of the produced roller is as shown in Table 3.

(Method for manufacturing fixing roller 3)
When forming the release layer, a layer having a thickness of 60 μm is formed by spray coating, and after drying, a 50 μm layer is further formed by using a ring coating apparatus, so that the release layer has a thickness of 110 μm. A fixing roller 3 was obtained in the same manner as the fixing roller 2 except that polishing was not performed after layer formation. The outline of the produced roller is as shown in Table 3.

(Method for manufacturing fixing roller 4)
When forming a release layer, a layer having a thickness of 140 μm is formed by spray coating, and after drying, a 50 μm layer is further formed using a ring coating apparatus, so that the thickness of the release layer is 190 μm. Was manufactured in the same manner as the fixing roller 1 to obtain the fixing roller 4. The outline of the produced roller is as shown in Table 3.

(Method for Manufacturing Fixing Roller 5)
A fixing roller 5 was obtained in the same manner as the fixing roller 1 except that the thickness of the release layer was changed to 5 μm using a ring coating apparatus. The outline of the produced roller is as shown in Table 3.

(Method for Manufacturing Fixing Roller 6)
A fixing roller 6 was obtained in the same manner as the fixing roller 5 except that the release layer dispersion used in forming the release layer was changed to the release layer dispersion 2. The outline of the produced roller is as shown in Table 3.

(Method for manufacturing fixing roller 7)
The heat storage layer coating solution to be used is changed to the heat storage layer coating solution 2, and when the heat storage layer is formed, a layer having a thickness of 200 μm is formed by spray coating, and after drying, an additional 50 μm is formed using a ring coating device. A fixing roller 7 was obtained in the same manner as the fixing roller 1 except that the thickness of the heat storage layer was changed to 250 μm by forming a layer. The outline of the produced roller is as shown in Table 3.

(Method for manufacturing fixing roller 8)
The heat storage layer coating solution to be used is changed to the heat storage layer coating solution 3, and when the heat storage layer is formed, a layer having a thickness of 50 μm is formed by spray coating, and after drying, an additional 50 μm is formed using a ring coating apparatus. A fixing roller 8 was obtained in the same manner as the fixing roller 1 except that the thickness of the heat storage layer was changed to 100 μm by forming a layer. The outline of the produced roller is as shown in Table 3.

(Method for manufacturing comparative fixing roller 1)
A comparative fixing roller 1 was obtained in the same manner as the fixing roller 8 except that the heat storage layer coating solution used was changed to the heat storage layer coating solution 4. The outline of the produced roller is as shown in Table 3. For the comparative fixing roller 1 only, the “surface existence ratio” in the table indicates the existence ratio of zirconium with respect to the total amount of elements detected by EPMA measurement. Zirconium is derived from zirconia used in the comparative fixing roller 1 instead of the heat conductive filler.

(Method for manufacturing comparative fixing roller 2)
A fixing roller is formed except that when the heat storage layer is formed, a layer having a thickness of 220 μm is formed by spray coating, and after drying, a layer having a thickness of 50 μm is further formed by using a ring coating apparatus to thereby set the thickness of the heat storage layer to 270 μm. The fixing roller 2 for comparison was obtained. The outline of the produced roller is as shown in Table 3.

(Manufacturing method of comparative fixing roller 3)
A fixing roller is formed except that when the heat storage layer is formed, a layer having a thickness of 30 μm is formed by spray coating, and after drying, a layer having a thickness of 50 μm is further formed by using a ring coating apparatus so that the thickness of the heat storage layer is 80 μm. 8 was manufactured in the same manner as described above to obtain a comparative fixing roller 3. The outline of the produced roller is as shown in Table 3.

(Method for manufacturing comparative fixing roller 4)
When forming a release layer, a layer having a thickness of 170 μm is formed by spray coating, and after drying, a 50 μm layer is further formed by using a ring coating apparatus, so that the release layer has a thickness of 220 μm. Was manufactured in the same manner as the fixing roller 1 to obtain a comparative fixing roller 4. The outline of the produced roller is as shown in Table 3.

(Method for manufacturing comparative fixing roller 5)
A comparative fixing roller 5 was obtained in the same manner as the fixing roller 1 except that a 3 μm layer was formed using a ring coating apparatus when forming the release layer. The outline of the produced roller is as shown in Table 3.

(Method for manufacturing comparative fixing roller 6)
A comparative fixing roller 6 was obtained in the same manner as the fixing roller 1 except that the release layer dispersion used in forming the release layer was changed to the release layer dispersion 3. The outline of the produced roller is as shown in Table 3.

(Method for manufacturing comparative fixing roller 7)
A comparative fixing roller 7 was obtained in the same manner as the fixing roller 1 except that the release layer dispersion used in forming the release layer was changed to the release layer dispersion 4. The outline of the produced roller is as shown in Table 3.

  Hereinafter, the present invention will be described with reference to toners used in production examples and examples, but the present invention is not limited in any way as long as desired performance is satisfied. In addition, all the parts in the following mixing | blending are a mass part.

<1> Magnetic material (Production Example 1 of surface-treated magnetic material)
An aqueous solution containing ferrous hydroxide was prepared by mixing 1.0 to 1.1 equivalents of caustic soda solution with ferrous sulfate aqueous solution.

  While maintaining the pH of the aqueous solution at around 9, air was blown, and an oxidation reaction was performed at 80 ° C. or higher and 90 ° C. or lower to prepare a slurry liquid for generating seed crystals.

Subsequently, after adding ferrous sulfate aqueous solution to this slurry liquid so that it may become 0.9 equivalent or more and 1.2 equivalent or less with respect to the initial amount of alkali (sodium component of caustic soda), the slurry liquid was maintained at about pH 8. Then, the oxidation reaction was promoted while blowing air, and the magnetic iron oxide particles generated after the oxidation reaction were washed, filtered and once taken out. At this time, a small amount of water-containing sample was collected and the water content was measured. Next, this water-containing sample was re-dispersed in another aqueous medium without drying, and then the pH of the re-dispersed liquid was adjusted to about 6, and the silane coupling agent (n-C ₄ H _{9 was} thoroughly stirred. 1.0 part by mass of Si (OC ₂ H ₅ ) ₃ ) is added to 100 parts by mass of magnetic iron oxide (the amount of magnetic iron oxide is calculated as a value obtained by subtracting the water content from the water-containing sample), and the coupling treatment is performed. went. The produced hydrophobic iron oxide particles were washed, filtered and dried by a conventional method, and then the slightly agglomerated particles were crushed to obtain a surface-treated magnetic body 1. The degree of hydrophobicity of this magnetic material was 55%.

(Production Example 2 of Surface-treated Magnetic Material)
In the same manner as in Production Example 1 of the surface-treated magnetic material, except that the silane coupling agent is changed to (n-C ₂₂ H ₄₅ Si (OC ₂ H ₅ ) ₃ ) and the number of added parts is 1.5 parts by mass. Thus, the surface-treated magnetic body 2 was obtained. The degree of hydrophobicity of this magnetic material was 87%.

(Production Example 1 of Untreated Magnetic Material)
In the same manner as in Production Example 1 of the surface-treated magnetic material, the oxidation reaction proceeds, the magnetic material produced after the oxidation reaction is finished, washed, filtered and dried, and the aggregated particles are crushed to obtain the untreated magnetic material 1 It was.

<2> Production of Magnetic Toner 1 After adding 451 parts by mass of 0.1 mol / liter-Na ₃ PO ₄ aqueous solution to 709 parts by mass of ion-exchanged water and heating to 60 ° C., 1.0 mol / liter-CaCl ₂ aqueous solution 67 7 parts by mass were gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ .

On the other hand, the following prescription was uniformly dispersed and mixed using an attritor (Mitsui Miike Chemical Co., Ltd.).
Styrene 75 parts by mass n-butyl acrylate 25 parts by mass Saturated polyester resin (1) 3 parts by mass (monomer composition; bisphenol A propylene oxide adduct / terephthalic acid / isophthalic acid, acid value; 9 mg KOH / g, Tg (glass Transition temperature) = 69 ° C., Mn (number average molecular weight) = 4200, Mw (weight average molecular weight) = 9000)
Negative charge control agent 2 parts by mass (T-77; monoazo dye-based Fe compound (Hodogaya Chemical Co., Ltd.))
・ Crosslinking agent (1,9-nonanediol dimethacrylate: Kyoeisha Scientific Co., Ltd.)
0.5 parts by mass

・表面処理磁性体１ ９０質量部

・ 90 parts by mass of surface-treated magnetic material 1

  This monomer composition was heated to 60 ° C., and 15 parts by mass of HNP-9 (polyethylene wax, DSC endothermic main peak = 78 ° C.) manufactured by Nippon Seiwa Co., Ltd. was mixed and dissolved therein. A polymerizable monomer system was obtained by dissolving 2 parts by mass of butyl peroxide.

The polymerizable monomer system was put into the aqueous medium, and the mixture was granulated by stirring at 12,000 rpm for 15 minutes with Claremix (manufactured by M Technique) in an N ₂ atmosphere at 60 ° C. Thereafter, while stirring with a paddle stirring blade, the initial reaction temperature was set to 40 ° C., the temperature was raised to 60 ° C. after 0.5 hours and 70 ° C. after 1.0 hour, and then reacted for 3 hours. Thereafter, stirring was continued for another 10 hours. After completion of the reaction, the suspension was cooled, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) ₂ , filtered, washed with water, and dried to obtain a magnetic toner base.

Hydrophobic silica fine powder having a BET specific surface area of 180 m ² / g after treatment with hexamethyldisilazane and then with silicone oil (primary average particle size 10 nm, hydrophobization degree 82). The magnetic toner 1 (weight average particle diameter 7.5 μm) shown in Table 4 was prepared by mixing 1.0 part by mass of the body (1) with a Henschel mixer (Mitsui Miike Chemical Co., Ltd.).

Production of Magnetic Toner 2 Magnetic toner 2 was prepared in the same manner as in Production Example of Magnetic Toner 1 except that the initial reaction temperature was adjusted to 60 ° C. and adjusted to 70 ° C. after 0.5 hours of reaction. Table 5 shows the physical properties of the magnetic toner 2.

Production of magnetic toner 3 Same as the production example of magnetic toner 1 except that 0.4 parts by mass of 1,6-hexanediol diacrylate (1,6-HDDA) was used instead of 1,9-nonanediol dimethacrylate. Thus, magnetic toner 3 was prepared. Table 5 shows the physical properties of the magnetic toner 3.

Production of magnetic toner 4 A magnetic toner 4 was prepared in the same manner as in the production example of the magnetic toner 3 except that 0.15 parts by mass of 1,6-hexanediol diacrylate was used. Table 5 shows the physical properties of the magnetic toner 4.

Production of Magnetic Toner 5 Magnetic toner 5 was prepared in the same manner as in Production Example of Magnetic Toner 1 except that 1.5 parts by mass of PEG # 400 dimethacrylate was used instead of 1,9-nonanediol dimethacrylate. Table 5 shows the physical properties of the magnetic toner 5.
・ Crosslinking agent (PEG # 400 dimethacrylate)

Production of Magnetic Toner 6 Magnetic toner 6 was prepared in the same manner as in Production Example of Magnetic Toner 1 except that 0.02 parts by mass of divinylbenzene was used instead of 1,9-nonanediol dimethacrylate. Table 5 shows the physical properties of the magnetic toner 6.

Production of Magnetic Toner 7 Using 4 parts by mass of polymerization initiator butyl peroxide, adjusting the initial reaction temperature to 60 ° C., adjusting to 70 ° C. after 0.5 hours of reaction, Magnetic toner 6 was prepared in the same manner as in magnetic toner 1 except that 0.1 part by weight of divinylbenzene was used instead of methacrylate. Table 5 shows the physical properties of the magnetic toner 6.

Manufacture of magnetic toner 8 Instead of 1,9-nonanediol dimethacrylate, 2.5 parts by mass of pentaerythritol tetraacrylate represented by the following formula (A) is added, and surface-treated magnetic material is used instead of surface-treated magnetic material 1 No. 2 was used, the initial reaction temperature was 60 ° C., and the temperature was raised to 70 ° C. after 0.5 hours. Table 5 shows the physical properties of the magnetic toner 8.

Production of magnetic toner 9 A magnetic toner 9 was prepared in the same manner as in the production example of the magnetic toner 8 except that the amount of pentaerythritol tetraacrylate added was changed to 0.7 parts by mass. Table 5 shows the physical properties of the magnetic toner 9.

Production of magnetic toner 10 Styrene / n-butyl acrylate copolymer (mass ratio 78/22) 100 parts by weight Saturated polyester resin 1 Number average molecular weight 10,000, acid value 105 parts by weight Negative charge control agent (monoazo dye system) Fe compound) 1 part by weight Untreated magnetic substance 90 parts by weight Ester wax used in toner 1 10 parts by weight The above materials were mixed in a blender, melted and kneaded with a biaxial extruder heated to 130 ° C., and cooled and kneaded. The product was coarsely pulverized with a hammer mill, the coarsely pulverized product was finely pulverized with a jet mill, and the resulting finely pulverized product was air-classified to obtain toner particles having a weight average particle size of 8.1 μm. To 100 parts by mass of the toner particles, 1.0 part by mass of silica used in Production Example 1 of magnetic toner was added, and a Henschel mixer was used to mix the stirring blades at a peripheral speed of 40 m / sec for 3 minutes. Was prepared. Table 5 shows the physical properties of the magnetic toner 10.

  The production methods of toners 1 to 10 are summarized in Table 4. In addition, Table 5 summarizes the physical properties of the toners 1 to 10.

{Evaluation methods}
Example 1 was evaluated under the conditions described below.

<Low temperature fixability>
As an image forming apparatus, LBP3000 (14 sheets / min, manufactured by Canon Inc.) equipped with the fixing roller of the present invention was used. Here, the process speed was set to 140 mm / sec. Under this condition, the magnetic toner 1 was used, and the experiment was started from a state in which the temperature of the entire fixing device was adapted to the ambient temperature (hereinafter, this condition is referred to as a cold start). ). The fixing test was performed in an atmosphere of normal temperature and humidity (23 ° C., 60 RH).

First, a halftone image is formed on the FOX RIVER BOND paper so that the image density is 0.8 or more and 0.85 or less, the first printout time is set to 20 seconds, and the fixing device temperature is set to 150 ° C. to 5 ° C. The image was fixed by raising it step by step. Thereafter, the fixed image was rubbed 10 times with a Sylbon paper to which a load of 55 g / cm ² was applied, and the temperature at which the density reduction rate of the fixed image after the rub was 10% was defined as the fixing start temperature.
A: Less than 165 ° C (good)
B: 165 ° C or higher and lower than 175 ° C (no problem in practical use)
C: 175 ° C. or higher and lower than 185 ° C. (preferably not practically acceptable level)
D: 185 ° C or higher (practical problem)

<Low temperature offset test>
Regarding the low temperature offset resistance, the temperature at which the stain due to the offset phenomenon occurred on the image in the fixing test was visually confirmed. The lower the temperature, the better the low temperature offset resistance.
A: Less than 145 ° C (good)
B: 145 ° C or higher and lower than 155 ° C (no problem in practical use)
C: 155 ° C. or higher and lower than 165 ° C. (preferably not practically acceptable level)
D: 165 ° C or higher (practical problem)

<Image evaluation>
In a low-temperature and low-humidity environment (14 ° C., 10% RH), an image endurance test of 2,000 sheets was performed in an intermittent mode using an 8-point A letter and a print rate of 5%. Note that Xerox letter paper (75 g / m ² ) was used as a recording medium.

Image evaluation 1 [Image density]
The image density formed a solid image portion, and the average density of a total of five points at the four corners and the center of the solid image was measured with a Macbeth reflection densitometer RD918 (manufactured by Macbeth).
A: 1.35 or more B: 1.3 or more and less than 1.35 C: 1.25 or more and less than 1.30 D: less than 1.25

<Fixing trail>
Using a device similar to the development durability test, 10 horizontal ruled lines with a printing rate of 4% were printed continuously, and the 10th image was evaluated according to the following criteria. On the opposite side of the paper traveling direction, tailing was determined based on the level at which a small thorn-like or thread-like scissor line was generated from the horizontal ruled line.
A: There is no tailing at all. (Good)
B: Some minor tailing occurs. (No problem in practical use)
C: Several large tails are mixed with minor tails. (Not preferable, but practically acceptable level)
D: Many large tailings are seen. (There are practical problems)

<Preservability>
10 g of toner was put in a 50 ml polycup and allowed to stand for 3 days in a thermostatic bath at 50 ° C., and the degree of blocking of the toner was evaluated.
A: The fluidity of the toner does not change. B: The fluidity is deteriorated but recovers immediately. C: There is an agglomerate and is not easily loosened.
D: There is no fluidity or caking occurs, and this is an unfavorable level for practical use.

  As for Example 1, all the good results were obtained in the evaluation performed in the present invention.

  Similarly, evaluation was performed on Examples 2 to 14 and Comparative Examples 1 to 10, and the results are summarized in Table 6.

1 is a schematic view of an image heating member (fixing roller) to which the present invention can be applied. It is a schematic diagram explaining the ring coating apparatus which can be preferably used for manufacture of the thermal storage layer of the image heating member of this invention. 1 is a schematic cross-sectional view of an image forming apparatus to which the present invention can be applied. 1 is a schematic cross-sectional view of a fixing device to which the present invention can be applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Photoconductor 7 Heat-fixing apparatus 21 Heater 21a for plate | board heating Substrate 21b Heating resistance layer 21c Insulating protective layer 21d Sliding layer 22 Thermistor 24 Heater holder 30 Fixing roller 31 Core metal 32 Low heat conduction elastic layer 33 High heat conduction Layer 34 High thermal conductivity release layer 41 Core metal 42 Elastic layer 43 Release layer 63 Pressure roller Nh Heating nip Nt Fixing nip P Recording material T Toner

Claims (23)

A charging step of charging the electrostatic latent image carrier with charging means, an exposure step of exposing the charged electrostatic latent image carrier to form an electrostatic latent image, and developing the electrostatic latent image with toner Development process for forming a toner image, transfer process for transferring the toner image to a recording material with or without an intermediate transfer member, and an image heating member capable of rotating the recording material carrying the toner image with a pressure member In an image forming method having a fixing step of fixing by heating and pressing by passing through a nip formed by
The image heating member is heated from the outermost surface by an external heating means,
The image heating member is a roller having a release layer having a thickness of 5 μm or more and 200 μm or less as an outermost layer, a heat storage layer as a lower layer, and an elastic layer as a lower layer,
The image heating member contains a heat conductive filler having a heat conductivity of 5.0 W / mK or more,
The thermally conductive filler is Al and / or Zn compound,
When the surface of the image heating member is measured by EPMA (electron beam microanalyzer), the abundance ratio of Al and / or Zn elements derived from the heat conductive filler is set to 0. 0 with respect to the total amount of elements detected by EPMA. 10 mass% or more and 3.00 mass% or less,
Heat capacity per unit area of the heat storage layer is not more than 100 J / m ² K or more 600J / m ² K,
The toner has an activation energy Ea (kJ / mol) calculated from a shift factor aT at that time, which is 110 (kJ / mol) or less in a master curve when 120 ° C. is a reference temperature. Method.   2. The image forming method according to claim 1, wherein the surface roughness Rz of the image heating member is 1.0 μm or more and 10.0 μm or less.   3. The image forming method according to claim 1, wherein the release layer of the image heating member is a solid rubber layer mainly composed of fluoro rubber.   4. The image forming method according to claim 1, wherein the heat storage layer of the image heating member contains a heat conductive filler in an amount of 10% by mass to 50% by mass.   The image forming method according to claim 1, wherein the image heating member has a micro hardness of 30 ° to 68 °.   The image forming method according to claim 1, wherein the elastic layer has a thermal conductivity of 0.15 W / mK or less. In the master curve of the toner at 120 ° C. as the reference temperature, the activation energy obtained from the shift factor aT at that time is Ea (kJ / mol), and the toner is extracted with Soxhlet extraction with tetrahydrofuran (THF). The image forming method according to any one of claims 1 to 6, wherein the following relational expression (1) is satisfied when THF-insoluble matter derived from a component of the resin is contained in A%.
Ea / A ≦ 5.0 (Formula 1)   The image forming method according to any one of claims 1 to 7, wherein a molecular weight of a peak top is 15000 or more and 30000 or less in gel permeation chromatography (GPC) measurement of a THF soluble content of the toner.   9. The image forming method according to claim 1, wherein an average circularity of the toner is 0.950 or more.   10. The image forming method according to claim 1, wherein the toner is a toner obtained by polymerizing a polymerizable monomer composition in an aqueous medium.   11. The image forming method according to claim 1, wherein the toner contains at least a binder resin, a wax, and a magnetic material. In a fixing method in which a toner image formed on a recording material is heated and pressurized and fixed by passing through a nip formed by a pressure member and a rotatable image heating member.
The image heating member is heated from the outermost surface by an external heating means,
The image heating member is a roller having a release layer having a thickness of 5 μm or more and 200 μm or less as an outermost layer, a heat storage layer as a lower layer, and an elastic layer as a lower layer,
The image heating member contains a heat conductive filler having a heat conductivity of 5.0 W / mK or more,
The thermally conductive filler is Al and / or Zn compound,
When the surface of the image heating member is measured by EPMA (electron beam microanalyzer), the abundance ratio of Al and / or Zn elements derived from the heat conductive filler is set to 0. 0 with respect to the total amount of elements detected by EPMA. 10 mass% or more and 3.00 mass% or less,
Heat capacity per unit area of the heat storage layer is not more than 100 J / m ² K or more 600J / m ² K,
The toner has a master curve when the reference temperature is 120 ° C., and the activation energy Ea (kJ / mol) obtained from the shift factor aT at that time is 110 (kJ / mol) or less. . In the master curve of the toner at 120 ° C. as the reference temperature, the activation energy obtained from the shift factor aT at that time is Ea (kJ / mol), and the toner is extracted with Soxhlet extraction with tetrahydrofuran (THF). The fixing method according to claim 12, wherein the following relational expression (1) is satisfied when a THF-insoluble content derived from a component of the adhesion resin is contained by A%.
Ea / A ≦ 5.0 (Formula 1)   14. The fixing method according to claim 12, wherein a molecular weight of a peak top is 15000 or more and 30000 or less in gel permeation chromatography (GPC) measurement of THF soluble content of the toner.   The fixing method according to claim 12, wherein the toner has an average circularity of 0.950 or more.   The fixing method according to claim 12, wherein the toner is a toner obtained by polymerizing a polymerizable monomer composition in an aqueous medium.   The fixing method according to claim 12, wherein the toner contains at least a binder resin, a wax, and a magnetic material. A charging step of charging the electrostatic latent image carrier with charging means, an exposure step of exposing the charged electrostatic latent image carrier to form an electrostatic latent image, and developing the electrostatic latent image with toner Development process for forming a toner image, transfer process for transferring the toner image to a recording material with or without an intermediate transfer member, and an image heating member capable of rotating the recording material carrying the toner image with a pressure member A fixing step of fixing by heating and pressing by passing through a nip formed by
The image heating member is heated from the outermost surface by an external heating means,
The image heating member is a roller having a release layer having a thickness of 5 μm or more and 200 μm or less as an outermost layer, a heat storage layer as a lower layer, and an elastic layer as a lower layer,
The amount of the filler having a thermal conductivity of 5.0 W / mK or more in the surface portion of the image heating member is 0.10% by mass or more and 3.00% by mass or less,
In the toner the heat capacity per unit area of the heat storage layer is applied to an image forming method is not more than 100 J / m ² K or more 600J / m ² K,
The toner is characterized in that the activation energy Ea (kJ / mol) obtained from the shift factor aT at that time is 110 (kJ / mol) or less in the master curve when the reference temperature is 120 ° C. In the master curve of the toner at 120 ° C. as the reference temperature, the activation energy obtained from the shift factor aT at that time is Ea (kJ / mol), and the toner is extracted with Soxhlet extraction with tetrahydrofuran (THF). The toner according to claim 18, wherein the following relational expression (1) is satisfied when A% of the THF-insoluble component derived from the component of the adhesion resin is contained.
Ea / A ≦ 5.0 (Formula 1)   20. The toner according to claim 18, wherein the toner has a peak top molecular weight of 15000 or more and 30000 or less in gel permeation chromatography (GPC) measurement of THF-soluble matter of the toner.   The toner according to claim 18, wherein the toner has an average circularity of 0.950 or more.   The toner according to claim 18, wherein the toner is a toner obtained by polymerizing a polymerizable monomer composition in an aqueous medium.   The toner according to any one of claims 18 to 22, wherein the toner contains at least a binder resin, a wax, and a magnetic substance.

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