JP2005181489A - Resin for toner, toner, and image forming method using the toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin for a toner with which an image density is satisfactory, even when print out of multiple sheets is performed, the degradation in inversion fogging can be suppressed and images of satisfactory gradation characteristics can be obtained, to provide a toner and an image forming method which uses the toner. <P>SOLUTION: The resin for the toner, which is a copolymer obtained by copolymerizing at least (M1) methyl (meth)acrylate and (M2) SO<SB>3</SB>x group-containing polymerizable monomer and is 5:95 to 80:20 in mass ratio of the M1 and the M2, is incorporated into the toner; and the toner is used for the image forming method. X represents one or more kinds selected from among H, Na, K, NH<SB>4</SB>, Ca, and Mg. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a toner used in an image forming method such as an electrophotographic method, an electrostatic recording method, a magnetic recording method, and a toner jet method, and an image forming method using the toner.

  Conventionally, a number of methods are known as electrophotographic methods. In general, an electric latent image is formed on an electrostatic image carrier (hereinafter also referred to as a photoreceptor) by various means using a photoconductive substance. Then, the latent image is developed with toner to form a visible image. If necessary, the toner image is transferred to a transfer material such as paper, and then the toner image is fixed on the transfer material by heat and pressure. To obtain a copy.

  As a method of visualizing an electric latent image with toner, a cascade development method, a magnetic brush development method, a pressure development method, a magnetic brush development method using a two-component developer composed of a carrier and a toner, a toner carrier is a photoreceptor. Non-contact one-component development method that causes toner to fly from the toner carrier to the photoconductor in a non-contact manner, a contact one-component development method in which the toner carrier is pressed against the photoconductor and the toner is transferred by an electric field, and magnetic toner is used. A so-called jumping method is also used in which a rotating sleeve having a magnetic pole at the center is used to fly between the photosensitive member and the sleeve by an electric field.

  In the jumping method, an insulating magnetic developer is applied onto a developer carrying member, and this is triboelectrically charged. Then, it is placed in close proximity to the electrostatic latent image under the action of a magnetic field, and is opposed without contact, This is a developing method. According to this method, the insulating magnetic developer is thinly coated on the developer carrying member, thereby enabling sufficient frictional charging of the developer, and in contact with the electrostatic latent image while supporting the developer by magnetic force. Since the development is performed without any problem, the transfer of the developer to the non-image portion, so-called fogging, is suppressed, and a high-definition image can be obtained.

  Such a one-component development method does not require carrier particles such as glass beads and iron powder as in the two-component method, and therefore the development apparatus itself can be reduced in size and weight. Furthermore, since the two-component development method needs to keep the toner concentration in the developer constant, an apparatus that detects the toner concentration and replenishes the necessary amount of toner is required. Therefore, the developing device is also large and heavy here. Since such a device is not necessary in the one-component development method, it is preferable because it can be made small and light.

  By the way, the developer used in the image forming process is composed of a toner mainly composed of a binder resin and a colorant. In addition, in order to bring out characteristics necessary as a toner such as a charge control agent and a release agent. Contains the additive. As a colorant for the magnetic toner, a magnetic material is used as it is, or carbon black or a nonmagnetic inorganic compound, an organic pigment, a dye, or the like is used together with the magnetic material.

  However, the developing method using the insulating magnetic toner has unstable elements related to the insulating magnetic toner to be used. One of them is that a considerable amount of fine powdered magnetic material is mixed and dispersed in the insulating magnetic toner, and a part of the magnetic material is exposed or released on the surface of the toner particles. Since the fluidity and triboelectric chargeability are insufficient, and various performances required for the toner such as development characteristics (particularly, fog suppression) and transferability of the magnetic toner are still unsatisfactory, That is, a large amount of toner tends to remain on the photoreceptor. The remaining toner may scrape the photoconductor in the cleaning unit or contaminate the charging member in the charging unit, causing image defects. In particular, when a contact charging member that generates less ozone in the charging step is used, the member is significantly contaminated, and an extremely poor image may be obtained. Therefore, it is necessary to suppress the amount of toner remaining on the photoreceptor after the transfer process as much as possible.

  When the conventional magnetic toner is used, the above-mentioned problems occur because the transferability and development characteristics of the magnetic toner are still insufficient, and the adhesion force and frictional charging of the magnetic toner to the photoconductor. The amount of non-uniformity is considered to be a major cause. That is, magnetic particles having a relatively low resistance compared to the resin constituting the toner are likely to be exposed or released on the surface of the magnetic toner, so that the toner fluidity is likely to be lowered and the toner charge amount is uneven. In addition to being easily formed, general irregular toner has a large adhesion area with the photosensitive member, and therefore has a large adhesion force. Therefore, image characteristics such as transfer residual toner and fog toner are deteriorated. Such a problem appears particularly conspicuously under high humidity where the triboelectric charge amount tends to decrease. Although means for incorporating a charge control agent is commonly used for improving the triboelectric chargeability, it cannot be said that the adverse effects of the free magnetic powder can be sufficiently excluded.

  By the way, LED and laser beam printers have become the mainstream in the recent market as printer devices, and the direction of technology is higher resolution, that is, the conventional 300, 400 dpi has become 600, 1200 dpi. Accordingly, with this development, higher definition has been demanded. In addition, copiers are also becoming more sophisticated, and therefore are moving toward digitalization. Since this method mainly uses a method of forming an electrostatic latent image with a laser, it is also proceeding in the direction of high resolution, and here again, a high-resolution and high-definition developing method has been required as in the case of a printer. Yes. As one means for satisfying this requirement, toner particle size reduction is progressing, and Japanese Patent Laid-Open Nos. 1-112253, 1-191156, 2-214156, and 2-284158 are disclosed. JP-A-3-181952 and JP-A-4-162048 propose a toner having a specific particle size distribution and a small particle size.

  However, as the toner particle size becomes smaller, stable tribocharging of the toner powder becomes an important technique. In other words, unless the fine individual toner particles have a uniform charge amount, the above-described decrease in image stability is more likely to appear. This is because the toner particle size is simply reduced, and the adhesion force (mirror image force, van der Waals force, etc.) of the toner particles to the photoreceptor is larger than the Coulomb force applied to the toner particles in the transfer process. As a result, in addition to the increase in the residual toner, the reduction in the toner diameter is accompanied by a deterioration in fluidity, so that the charge amount of individual toner particles tends to be non-uniform, resulting in fog and toner particles having poor transferability. This is because it increases.

  On the other hand, the toner is manufactured as a toner having a desired particle size by melting and mixing a binder resin, a colorant, and the like, uniformly dispersing, pulverizing with a fine pulverizer, and classifying with a classifier (pulverization method). However, there is a limit to the range of materials that can be used to reduce the particle size of the toner. For example, the resin colorant dispersion must be sufficiently brittle and capable of being finely pulverized by an economically usable production apparatus. From this requirement, in order to make the resin colorant dispersion brittle, when the resin colorant dispersion is actually finely pulverized at a high speed, particles having a wide particle size range are easily formed, and in particular, a relatively large proportion of fine particles ( There arises a problem that excessively pulverized particles) are included therein. Further, such highly brittle materials are often further pulverized or powdered when used as developing toners in copying machines and the like. In addition, as described above, the adhesion between the pulverized particle surface and the photosensitive member is also large.

  Also, in the pulverization method, it is difficult to completely disperse solid fine particles such as magnetic powder or colorant into the resin, and depending on the degree of dispersion, fogging may increase and image density may decrease. . Furthermore, since the pulverization method essentially releases a large amount of magnetic iron oxide particles on the surface of the toner, problems still remain in the triboelectric charging stability under harsh environments such as toner fluidity and high humidity. .

  That is, in the pulverization method, there is a limit to finer toner particles required for high definition and high image quality, and the powder characteristics, particularly the uniform chargeability and fluidity of the toner are significantly attenuated.

  In order to overcome the problems of the toner by the pulverization method as described above, and further to satisfy the above-described requirements, a toner production method by a suspension polymerization method has been proposed.

  The toner by suspension polymerization (hereinafter referred to as polymerized toner) can be easily finely divided into toner particles. Furthermore, since the shape of the obtained toner is spherical, it has excellent transferability and fluidity, and high image quality. It will be advantageous.

  However, by including a magnetic substance in the polymerized toner, its shape is easily changed from a spherical shape to a distorted one, and fluidity and charging characteristics are greatly reduced, and transferability and frictional charging uniformity are reduced. There is a tendency. This is because suspended particles are easily distorted when a magnetic material having a large specific gravity moves in the polymer material.

  In addition, since magnetic particles are generally hydrophilic, they are easily released from the toner surface during suspension polymerization, and the shape of the surface is distorted, making it difficult to obtain spherical particles. To do. Therefore, 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 for improving the dispersibility of a magnetic substance in a polymerized toner. For example, various silane coupling agent treatment techniques for magnetic materials are disclosed in Japanese Patent Application Laid-Open Nos. 59-200254, 59-2000025, 59-200277, and 59-224102. Japanese Laid-Open Patent Publication Nos. 63-250660 and 10-239897 disclose techniques for treating silicon element-containing magnetic particles with a silane coupling agent.

  However, although the dispersibility in the toner is improved to some extent by these treatments, there is a problem that it is difficult to uniformly hydrophobize the surface of the magnetic material. The generation of the magnetic particles cannot be avoided, and the toner particles are insufficient to make the shape of the toner particles into a good level, and it is also difficult to suppress the release of the magnetic particles from the surface.

  On the other hand, Japanese Patent Application Laid-Open No. 7-209904 discloses a developer technique that completely suppresses exposure of magnetic particles from the surface of toner particles.

  However, in such a toner, the magnetic particles are completely covered, so that the triboelectric charge amount is not moderated moderately. Therefore, the charge amount is likely to be excessive in a low humidity environment, so that it is caused by so-called charge-up. Deterioration of image density and deterioration of fog are likely to occur. In addition, since the charge control agent that should be present on the surface of the toner particles is also completely covered, it is still difficult to control the toner charge amount under high humidity.

  By the way, various methods have been devised for controlling the charge of the toner, and many proposals have been made for charge control agents used as toner raw materials. As a charge control agent, metal complexes mainly composed of heavy metals such as chromium and iron have been mainly studied, but due to environmental considerations, more stable chargeability requirements, manufacturing costs, etc., In recent years, proposals have been actively made to use a resin having a charge control function as a toner raw material.

  For example, Japanese Patent Publication No. 8-12467 discloses a charge control in which the copolymerization ratio of styrene and 2-acrylamido-2-methylpropanesulfonic acid is 98: 2 to 80:20 and the weight average molecular weight is 2000 to 15000. A pulverized toner containing 2 to 10 parts by weight of a functional copolymer is disclosed.

  Japanese Patent No. 2663016 discloses a copolymer having a copolymerization ratio of styrene and 2-acrylamido-2-methylpropanesulfonic acid of 98: 2 to 80:20 and a weight average molecular weight of 2000 to 15000 and a wax. Polymerized toners containing are disclosed.

  According to these publications, a toner having excellent chargeability can be obtained. However, when the present inventors examined these toners, when a large number of printouts were made, the toner charged to a reverse polarity gradually increased in the developing device, and so-called reversal fog rapidly deteriorated. It turns out that it has the problem of doing. In these publications, only a binary copolymer composed of styrene and 2-acrylamido-2-methylpropanesulfonic acid is described, but the glass transition temperature of the binary copolymer described is 90. The temperature was higher than or equal to ℃, and there were cases where problems occurred in low-temperature fixability.

  JP-A-11-184165 discloses a vinyl aromatic hydrocarbon having a weight ratio of sulfonic acid group-containing acrylamide of 0.1 to 1.8% by weight and a weight average molecular weight of 2000 to 15000, (meth) A nonmagnetic polymerization method toner containing 1 to 10 parts by weight of a copolymer composed of acrylate and sulfonic acid group-containing acrylamide is disclosed. According to this publication, a polymerized toner having excellent transparency and a sharp particle size distribution can be obtained. However, by reducing the content of the sulfonic acid group-containing acrylamide, there is a problem that only images with low image density and high fog can be obtained. The (meth) acrylate used in the publication is only used for adjusting the glass transition temperature. As an example of the (meth) acrylate that can be used, methacryl having a high theoretical glass transition temperature of 110 ° C. for homopolymers. Although methyl acid is also exemplified, there is no description in the examples, and there is no description regarding the change in chargeability of the toner by the introduction of methyl methacrylate. Further, this publication describes a nonmagnetic one-component polymerized toner, and no description of a magnetic polymerized toner containing a magnetic powder is found.

  JP-A-11-288129 discloses a co-polymerization of a sulfonic acid group-containing acrylamide and a vinyl monomer having a weight average molecular weight of 17000 to 25000 and a weight ratio of the sulfonic acid group-containing acrylamide of 0.1 to 10% by weight. Polymerized toners for non-magnetic one-component development containing coalescence are disclosed. JP-A-11-327208 discloses a polymerization color toner for non-magnetic one-component development, which contains a copolymer of a sulfonic acid group-containing acrylamide having a weight average molecular weight of 17000 to 25000 and a vinyl monomer. It is disclosed. According to these publications, by using a resin having a high weight average molecular weight, a toner having relatively good pigment dispersion and improved chargeability can be obtained. However, deterioration in low-temperature fixability due to an increase in weight average molecular weight is inevitable. Even if the pigment dispersion is sufficiently improved, the charging stability is still insufficient, and when a large number of sheets are printed out, the image density is lowered and the reversal fog is increased.

  Further, JP-A-2000-56518 discloses a polymerization color toner for non-magnetic one-component development containing a copolymer of a sulfonic acid group-containing acrylamide having a glass transition temperature of 30 to 70 ° C. and a vinyl monomer. Is disclosed. According to this publication, a toner having a low temperature fixability improved to some extent can be obtained. However, no improvement is seen with respect to the chargeability as compared with the prior art.

  Several proposals have been made for improving the chargeability of a resin having a charge control function. For example, Japanese Patent No. 2807795 includes (a) 2-acrylamido-2-methylpropanesulfonic acid, (b) a carboxyl group-containing monomer, (c) styrene, and (d) a hydroxyl group-containing monomer. a): Component (b) = 99: 5-70: 30%, (2) Components (a) and (b): Component (c) = 3: 97-20: 80%, (3) Component (a) , (B) and component (c): component (d) = 100 parts: 0.05 to 2.0 parts, (4) component (a) and component (b): component (d) = 100 parts: 20 parts Hereinafter, a pulverized toner containing 2 to 10 parts of a copolymer having a weight average molecular weight of 2000 to 15000 obtained by copolymerization at the following ratio is disclosed. JP-A-8-30017 discloses a resin charge control agent as a one-component toner used in a developing device in which a charge imparting member is pressed against a developer carrier disposed opposite to a latent image holding member. In this publication, the resin charge control agent contained in the toner includes (a) 2-acrylamido-2-methylpropanesulfonic acid, (b) a carboxyl group-containing monomer, (c) styrene, (D) Hydroxyl group-containing monomers were prepared by (1) component (a): component (b) = 99: 5-70: 30%, (2) components (a) and (b): component (c) = 3: 97-20: 80%, (3) Components (a), (b) and Component (c): Component (d) = 100 parts: 0.05-2.0 parts, (4) Component (a) and components (B): Ratio of component (d) = 100 parts: 20 parts or less Obtained by copolymerizing in a weight average molecular weight of the copolymer of 2,000 to 15,000 is disclosed. According to these publications, it is possible to obtain a toner having a relatively good rise in chargeability and excellent dispersion of various additives in the binder resin. However, there is room for further improvement with respect to the chargeability, and it cannot be said that the low-temperature fixability is sufficient. Furthermore, the toner described in this publication may not have sufficient transferability and may cause problems with image quality.

  JP-A No. 2000-13723 discloses at least one selected from styrene, (meth) acrylic acid ester, (meth) acrylic acid, sulfonic acid group-containing acrylamide, and (meth) acryloyloxyalkyldicarboxylic acid ester, 0.1-15 mass% of 1 or more types chosen from vinyl polycarboxylic acid, vinylsilanes, maleic anhydride, itaconic anhydride, glutaconic anhydride, and 2-carboxycinnamic acid anhydride are contained, and glass transition temperature is 45. A toner containing a resin having a weight average molecular weight of 100,000 or more, a weight average molecular weight to number average molecular weight ratio of 15 to 100, and a resin having a maximum value or a shoulder in each of a low molecular weight region and a high molecular weight region is disclosed. ing. According to this publication, a pulverized toner with improved chargeability can be obtained, but it cannot be said that it is sufficient, and there is room for further improvement. In addition, the toner described in this publication may not have sufficient transferability and may cause problems with image quality. Further, in this publication, (meth) acrylate is used only for adjusting the glass transition temperature, and methyl methacrylate is also exemplified as an example of (meth) acrylate that can be used. In addition, there is no description at all about the change in chargeability of the toner due to the introduction of methyl methacrylate.

  Japanese Patent Application Laid-Open No. 7-77839 discloses a toner having a number average molecular weight of 1500 to 10000 and a copolymer having a sulfonic acid group-containing acrylamide as an essential component as a structural unit as a charge control agent. In this publication, a technique is disclosed in which a fluorinated quaternary ammonium salt is contained in the toner as an auxiliary charge control agent together with the sulfonic acid group-containing acrylamide copolymer. According to this publication, a toner with improved chargeability can be obtained. However, it is not always easy to make a copolymer having a sulfonic acid group-containing acrylamide as a structural unit and a fluorine-containing quaternary ammonium salt in a toner in an extremely good and uniform dispersion state. There has been a problem that an improved toner may not be obtained or the toner may be poorly charged. In addition, the toner described in this publication may not have sufficient transferability and may cause problems with image quality.

  The present invention is to solve the above problems. That is, an object of the present invention is to provide a resin for toner, a toner, and a toner that can obtain an image having a good image density even when a large number of sheets are printed out, a deterioration in reversal fogging, and a good gradation property. An object of the present invention is to provide an image forming method using toner.

The present invention, at least M1) (meth) acrylate and M2) SO ₃ X (X represents H, Na, K, and NH _4, Ca, 1 or more selected from Mg) group-containing polymerizable monomer A toner resin, wherein the mass ratio of M1 to M2 is 5:95 to 80:20.

The present invention also provides a toner having inorganic fine powder on the surface of toner particles containing at least a binder resin and a colorant, wherein the toner particles include at least methyl (meth) acrylate and SO ₃ X (X is H A copolymer obtained by copolymerizing a group-containing polymerizable monomer at a mass ratio of 5:95 to 80:20 (which represents one or more selected from Na, K, NH ₄ , Ca, and Mg) A toner characterized by comprising

  The present invention further includes a charging step of applying a voltage to the charging member to charge the image carrier, an electrostatic latent image forming step of forming an electrostatic latent image on the charged image carrier, and an image carrier. A developing process in which the toner carried on the toner carrier is transferred to the formed electrostatic latent image to develop the toner image on the image carrier, and the toner image formed on the image carrier is used as a transfer material. In the image forming method in which image formation is repeatedly performed on the image carrier, the toner on the toner carrier in the development step is the toner of the present invention, and the charging step The image forming method is characterized in that the image carrier is charged by applying a voltage to a contact charging member that forms a contact portion with the image carrier and comes into contact therewith.

  According to the present invention, it is possible to obtain an image that has a good image density even when a large number of printouts are performed, suppresses the deterioration of inversion fog, and has a good gradation.

<1> Toner Resin of the Present Invention When the toner resin of the present invention is contained in a toner, it exhibits an excellent charge control function, and deterioration of reversal fog at the time of printing a large number of prints, which has been a problem in the past. Can be suppressed, and an image with good gradation can be obtained.

The resin for toner of the present invention represents at least M1) (meth) acrylate and M2) SO ₃ X (X is _{H, Na, K, NH 4} , Ca, 1 or more selected from Mg) group-containing It is a copolymer obtained by copolymerizing a polymerizable monomer, and it is essential that the mass ratio of M1 and M2 is 5:95 to 80:20. Here, SO ₃ X group of the SO ₃ X group-containing polymerizable monomer, believed to be the site expressing charging, the (meth) inversion fog upon a large number of sheets printed out methyl acrylate It is considered that the site has an effect of suppressing deterioration. The toner of the present invention contains the toner resin of the present invention in which the mass ratio of M1 and M2 is in the range of 5:95 to 80:20. Even when printed out, it is possible to obtain toner with very little reversal fog. If the mass ratio of M2 is smaller than this range and the ratio of M1 is larger than this range, there is a problem that the image density is low and fog is large because the charge amount is not sufficiently generated, and the mass ratio of M2 is within this range. If the ratio of M1 is larger than this range and the ratio of M1 is smaller than this range, the rise of charging is quick and the image density increases from the beginning, but the problem arises that inversion fog deteriorates when a large number of sheets are printed out.

Also, the toner resin of the present invention represents at least M1) (meth) acrylate, M2) SO ₃ X (X is _{H, Na, K, NH 4} , Ca, 1 or more selected from Mg) A group-containing polymerizable monomer, M3) styrene, and M4) a copolymer obtained by copolymerizing (meth) acrylic acid esters other than methyl (meth) acrylate, and the glass transition of the copolymer It is preferable that the temperature is 40 to 110 ° C., and the mass ratio of M1, M2, M3, and M4 satisfies the following relationship.
M1: M2 = 5: 95-80: 20
(M1 + M2): M3 = 0.1: 99.9 to 20:80
(M1 + M2 + M3): M4 = 70: 30 to 95: 5
The reason for introducing a (meth) acrylic acid ester other than styrene and methyl (meth) acrylate as a copolymerization component into the resin for toner of the present invention is that the polymerizable monomer containing methyl (meth) acrylate and SO ₃ X group In the binary copolymer consisting of only the polymer, uniform random copolymerization hardly occurs during polymerization, and the effect of suppressing deterioration of SO ₃ X group as a charging site and inversion fog is in the molecule. However, these comonomer ((meth) acrylic acid esters other than styrene and methyl (meth) acrylate) may cause the problem that the chargeability becomes unstable as a result. ) to be to coexist in the polymerization system at a specific ratio, can be easily introduced uniformly sO ₃ X group-containing polymerizable monomer and a (meth) acrylate in the molecule The effect of the present invention of suppressing reversal fog and excellent gradation is more easily manifested, and the compatibility with the binder resin, which is the raw material of the toner, is improved by introducing a specific ratio of the comonomer. The distribution of the resin for the toner among the toner particles becomes more uniform, and it is easy to obtain a toner with less fog, and the introduction of a comonomer improves the compatibility with the wax in the toner, resulting in a toner having excellent low-temperature fixability. It is easy to be done.

  These introduced comonomers M3 and M4 are (M1 + M2): M3 = 0.1: 99.9 to 20:80 and (M1 + M2 + M3): M4 = 70: 30 to 95: 5 It is preferable that the above-mentioned effects are difficult to obtain if these ranges are exceeded.

  In order to exhibit excellent low-temperature fixability and charging stability, the glass transition temperature of the resin for toner of the present invention is preferably in the range of 40 to 110 ° C, more preferably 50 to 80 ° C.

Further, the resin for toner according to the present invention has an SO ₃ X (X represents at least one selected from H, Na, K, NH ₄ , Ca, and Mg) group-containing polymerizable monomer. One or more selected from 2-methylpropanesulfonic acid (salt), sulfoalkyl (meth) acrylic acid (salt), allylsulfonic acid (salt), vinylsulfonic acid (salt), and styrenesulfonic acid (salt) Among them, acrylamide-2-methylpropanesulfonic acid (salt) and sulfoalkyl (meth) acrylic acid (salt) are more likely to cause more uniform random copolymerization, resulting in improved charging stability. It is particularly preferable because it is excellent.

  The peak molecular weight calculated by gel permeation chromatography (GPC) of a component soluble in tetrahydrofuran (THF) of the resin for toner of the present invention is preferably in the range of 2000 to 50000. The rise may be slow, and if it is larger than 50000, there may be a problem in low-temperature fixability.

  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 dissolving the toner resin in THF at room temperature for 24 hours is filtered through a solvent-resistant membrane filter having a pore diameter of 0.2 μm to obtain a sample solution, which is measured under the following conditions. In the sample preparation, the amount of THF is adjusted so that the concentration of the toner resin is 0.4 to 0.6% by mass.
Apparatus: High-speed GPC HLC8120 GPC (manufactured by Tosoh Corporation)
Column: Shodex KF-801, 802, 803, 804,
Seven series of 805, 806, 807 (made by Showa Denko KK)
Eluent: Tetrahydrofuran 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 (TSO standard polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F- manufactured by Tosoh Corporation) was used. 10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500).

M1) methyl (meth) acrylate, M2) SO ₃ X (X represents one or more selected from H, Na, K, NH ₄ , Ca, Mg) group-containing polymerizable monomer, and necessary As polymerization initiators that can be used when copolymerizing (meth) acrylic acid esters other than M3) styrene and M4) methyl (meth) acrylate according to the conditions, peroxide-based polymerization initiators, azo-based polymerization starts A variety of agents can be used.

  Examples of the peroxide polymerization initiator that can be used include peroxyesters, peroxydicarbonates, dialkyl peroxides, peroxyketals, ketone peroxides, hydroperoxides, diacyl peroxides, and inorganic ones. Examples of the system include persulfate and hydrogen peroxide. Specifically, t-butyl peroxyacetate, t-butyl peroxylaurate, t-butyl peroxypivalate, t-butyl peroxy- 2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxyneodecanoate, t-hexylperoxyacetate, t-hexylperoxylaurate, t-hexylperoxypivalate, t -Hexylperoxy-2-ethylhexanoate, t- Xylperoxyisobutyrate, t-hexylperoxyneodecanoate, t-butylperoxybenzoate, α, α'-bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, 1, 1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate Ate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxyisopropyl monocarbonate , T-butyl peroxyisopropyl monocarbonate, t-butyl -Oxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxy-m-toluoylbenzoate, bis (t-butylperoxy) Oxy) isophthalate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, 2,5-dimethyl-2,5-bis (m-toluoylperoxy) Peroxyesters such as hexane; diacyl peroxides such as benzoyl peroxide, lauroyl peroxide and isobutyryl peroxide; peroxydicarbons such as diisopropyl peroxydicarbonate and bis (4-t-butylcyclohexyl) peroxydicarbonate Ne 1,1-di-t-butylperoxycyclohexane, 1,1-di-t-hexylperoxycyclohexane, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, , 2-di-t-butylperoxybutane and other peroxyketals; di-t-butyl peroxide, dicumyl peroxide and t-butylcumyl peroxide and other dialkyl peroxides; A monocarbonate etc. are mentioned. Examples of the azo polymerization initiator that can be used include 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.

  If necessary, two or more of these polymerization initiators can be used simultaneously.

  The amount of the polymerization initiator used in this case is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the monomer, and when used in this range, the toner used is soluble in THF. The peak molecular weight calculated by GPC of the component can be 2000 to 50000.

  In addition, as the polymerization method, any method such as solution polymerization, suspension polymerization, emulsion polymerization, dispersion polymerization, precipitation polymerization, bulk polymerization and the like can be used, and although not particularly limited, methanol, isopropanol, It is particularly preferable to employ a solution polymerization method in which these monomer mixtures are copolymerized in an organic solvent containing a lower alcohol such as butanol.

<2> Toner of the Present Invention The toner of the present invention contains the resin for toner of the present invention described above, so that the image density is good even when a large number of sheets are printed out, and deterioration of reversal fog is suppressed. An image with good gradation can be obtained.

  The content of the resin for toner of the present invention is 0.1 to 20 parts by weight, preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the toner. Performance may not be obtained, and if it is more than 20 parts by mass, it is economically disadvantageous.

  The toner of the present invention may be used in combination with other charge control agents as necessary. 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. Further, when the toner is 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 and 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.

  The amount of the charge control agent used in combination 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. The binder resin is used in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

  The binder resin that is a constituent material of the toner of the present invention is arbitrarily selected from conventionally known materials, and examples thereof include styrene-acrylic copolymers, polyester resins, and epoxy resins.

  The glass transition temperature (Tg) of the binder resin is preferably 50 to 70 ° C. If the temperature is lower than 50 ° C., the storage stability of the toner is lowered, and if it is higher than 70 ° C., the fixability tends to be inferior. is there.

  The glass transition temperature (Tg) of the binder resin can be measured in the same manner as the endothermic peak obtained by differential thermal analysis of the wax described later. That is, the glass transition temperature (Tg) is determined in accordance with “ASTM D3418-8” using DSC-7 manufactured by PerkinElmer. 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. The measurement can be carried out by using an aluminum pan as a measurement sample, setting an empty pan for control, and measuring at a heating rate of 10 ° C./min.

  The peak molecular weight calculated by GPC of the resin component soluble in THF of the toner of the present invention is preferably in the range of 2000 to 50000, and if it is smaller than 2000, there may be a problem in chargeability, and it is larger than 50000. It becomes difficult to fix at low temperature. The method for measuring the peak molecular weight is the same as the method for measuring the molecular weight of the toner resin described above.

  Further, in the present invention, the content of the THF-insoluble content of the toner (a binder resin component that is three-dimensionally rendered insoluble in THF) is not particularly limited, but is usually 0 to 50% by mass, preferably based on the binder resin. Is in the range of 2-40% by weight, more preferably 5-30% by weight. The THF-insoluble matter is effective for high-temperature offset resistance, but it also has a serious detrimental effect on low-temperature fixability. If it exceeds 50% by mass, there are many problems with low-temperature fixability.

  The THF insoluble matter is measured as follows.

  Toner particles or 1 g of toner are precisely weighed and charged on a cylindrical filter paper, and Soxhlet extracted with 200 ml of THF for 20 hours. Thereafter, the cylindrical filter paper is taken out and vacuum-dried at 40 ° C. for 20 hours, and the weight of the residue is measured. Since the toner contains components other than the binder resin, such as a colorant, a wax component, and an external additive, the content of these toners and whether these are soluble or insoluble in THF are used as a reference. Calculate the THF-insoluble content. When a component other than the binder resin that is soluble in THF (for example, wax soluble in THF) is used, the content of the component is separately calculated and analyzed. It is converted to how much of the resin component is insoluble in THF.

  When the toner of the present invention contains a magnetic powder to form a magnetic toner, it is preferable that the magnetic powder is not substantially exposed on the toner surface. When the magnetic powder is exposed on the toner surface, stable chargeability cannot be obtained, and the members of the image forming apparatus are easily worn or scraped.

  Here, substantially no magnetic powder is present on the surface of the toner particles, for example, in the case of a toner containing iron oxide, carbon present on the surface of the toner particles measured by X-ray photoelectron spectroscopic analysis described later. The ratio (B / A) of the iron element content (B) to the element content (A) is less than 0.001.

  When the magnetic powder is contained in the toner of the present invention, it is preferable that the toner particles have a high charge amount, and for this purpose, it is necessary that the magnetic powder serving as a charge leakage site is not exposed on the surface. is there. Further, when a magnetic toner having a magnetic powder exposed on the surface of the toner particles is used, the photoconductor scraping due to the exposed magnetic powder becomes more prominent and tends to appear. However, if (B / A) as described above is less than 0.001, that is, a magnetic toner in which the magnetic powder is not substantially exposed on the surface of the toner particles is used, the abrasion of the photoreceptor can be significantly reduced. Is possible. Of course, the image forming method combined with the contact transfer process is also extremely effective, and it is possible to obtain a very high-definition image over a long period of time. Furthermore, it is more preferable that (B / A) is less than 0.0005, since the high image quality and durability stability are significantly improved.

  When the toner of the present invention is a magnetic toner containing magnetic powder, the ratio (B / A) of the content (B) of iron element to the content (A) of carbon element present on the surface of the magnetic toner particles is The surface composition analysis can be performed by ESCA (X-ray photoelectron spectroscopy).

In the present invention, the ESCA apparatus and measurement conditions are as follows.
Equipment used: PHI 1600S type X-ray photoelectron spectrometer Measurement conditions: X-ray source MgKα (400 W)
Spectral region 800μmφ
In the present invention, the surface atomic concentration is calculated from the measured peak intensity of each element using a relative sensitivity factor provided by PHI. The peak top range of each element is as follows.
C: 283-293 eV
Fe: 706 to 730 eV
In this measurement, the inorganic fine powder adhering to the toner particle surface is removed from the toner, and the toner particle is analyzed. Specifically, the magnetic toner is placed in a solvent that does not dissolve magnetic toner particles such as isopropyl alcohol, and ultrasonically cleaned, and the magnetic toner particles and the inorganic fine powder adhering to the surface of the magnetic toner particles are removed in the solvent. After the separation, decantation is repeatedly performed using a magnet or the like, the inorganic fine powder is removed together with the supernatant, the remaining toner particles are dried, and the ESCA is measured. The same measurement can be performed in the present embodiment described later.

  In the present invention, the magnetic powder contained in the toner particles to make the toner a magnetic toner includes magnetic iron oxides such as magnetite, maghematite, and ferrite, metals such as iron, cobalt, and nickel, or these metals and aluminum, cobalt, Examples include alloys of metals such as copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, and mixtures thereof.

  Among these, those mainly composed of magnetic iron oxide such as triiron tetroxide, γ-iron oxide, which may contain elements such as phosphorus, cobalt, nickel, copper, magnesium, manganese, aluminum, and silicon, can be mentioned. These may be used alone or in combination of two or more. These magnetic powders preferably have a Mohs hardness of 5-7.

  The shape of the magnetic powder includes octahedrons, hexahedrons, spheres, needles, flakes, and the like, but those having less anisotropy such as octahedrons, hexahedrons, spheres, and irregular shapes increase the image density. Preferred above. The shape of such magnetic powder can be confirmed by SEM or the like.

Further, the magnetic properties of the magnetic powder in the present invention include a saturation magnetization of 10 to 200 Am ² / kg, a residual magnetization of 1 to 100 Am ² / kg, and a coercive force of 1 to 30 kA / m under a magnetic field of 795.8 kA / m. Are preferably used.

  In the present invention, the magnetic properties of the magnetic powder can be measured by a method of measuring using an oscillating magnetometer VSMP-1-10 (manufactured by Toei Kogyo Co., Ltd.) at a room temperature of 25 ° C. and an external magnetic field of 796 kA / m. is there.

  When the toner of the present invention is a magnetic toner containing magnetic powder, the volume average particle size of the magnetic powder used is preferably 0.01 to 1.0 μm, more preferably 0.05 to 0.5 μm. . When the volume average diameter is less than 0.01 μm, the decrease in blackness becomes remarkable, the coloring power is insufficient as a colorant for black and white toner, and the agglomeration of magnetic powder particles becomes strong. Tend to get worse. On the other hand, when the volume average particle diameter exceeds 1.0 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 toners, it is probabilistically difficult to disperse the same number of magnetic powders in individual toner particles, and the dispersibility tends to deteriorate.

  The volume average particle size of the magnetic powder can be measured using a transmission electron microscope (TEM). Specifically, a powder sample of the toner to be measured is observed with a transmission electron microscope (TEM), and the diameter of 100 magnetic powder particles in the field of view is measured to obtain the volume average particle diameter.

  As a specific observation method by the above-mentioned TEM, after sufficiently dispersing particles to be observed in a room temperature curable epoxy resin, a cured product obtained by curing in an atmosphere at a temperature of 40 ° C. for 2 days, The method of observing as a flaky sample with a microtome equipped with diamond teeth is exemplified.

  In addition, when the toner of the present invention contains magnetic iron oxide particles and the toner is produced by a suspension polymerization method, the magnetic iron oxide particles to be used are preferably subjected to hydrophobic treatment on the particle surface in advance. When the surface of the iron oxide particles is hydrophobized, the magnetic iron oxide particles are hydrolyzed in a water-based medium while the coupling agent is hydrolyzed while the magnetic iron oxide particles are dispersed to have a primary particle size. This is particularly preferable because the surface of the particles is uniform and is appropriately hydrophobized. This hydrophobic treatment method is less likely to cause coalescence between the magnetic iron oxide particles than the dry treatment method in the gas phase, and the magnetic repulsion action between the magnetic iron oxide particles due to the hydrophobic treatment works. Is surface-treated in the form of primary particles.

  The method of treating the surface of magnetic iron oxide particles while hydrolyzing the coupling agent in an aqueous medium does not require the use of a coupling agent that generates gas, such as chlorosilanes and silazanes. In the gas phase, the magnetic iron oxide particles can be easily combined with each other, and a highly viscous coupling agent that has been difficult to be treated can be used, so that the hydrophobizing effect is great.

Examples of the coupling agent that can be used in the surface treatment of the magnetic iron oxide particles used in the present invention include a silane coupling agent and a titanium coupling agent. More preferably used are silane coupling agents, which are represented by the general formula (1).
R _m SiY _n (1)
[Wherein, 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 methacryl 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 (1) include vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, and methyltriethoxy. Examples include silane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, and n-octadecyltrimethoxysilane. it can.

In particular, the magnetic iron oxide particles are preferably hydrophobized in an aqueous medium using an alkyltrialkoxysilane coupling agent represented by the general formula (2).
_{C p H 2p + 1 -Si- (} OC q H 2q + 1) 3 (2)
[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 hydrophobizing treatment is easy, but it is difficult to sufficiently impart hydrophobicity, and it becomes difficult to suppress the exposure of the magnetic iron oxide particles from the toner particles. Further, when p is larger than 20, the hydrophobicity is sufficient, but the coalescence of the magnetic iron oxide particles increases, and it becomes difficult to sufficiently disperse the magnetic iron oxide particles in the toner. Tends to deteriorate.

  On the other hand, when q is larger than 3, the reactivity of the silane coupling agent is lowered and the hydrophobicity is not sufficiently performed. In particular, p in the formula 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 to 20 parts by mass, preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the magnetic iron oxide particles.

  In the present invention, the magnetic iron oxide particles are preferably hydrophobized in an aqueous medium. An “aqueous medium” is a medium containing water as a main component. Specific examples of the aqueous medium include water itself, water added with a small amount of a surfactant, water added with a pH adjusting agent, and water added with an organic solvent.

  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 parts by mass with respect to 100 parts by mass of water. Examples of the pH adjusting agent include inorganic acids such as hydrochloric acid. Examples of the organic solvent include methanol, and 0 to 500% of water may be added.

  In order to treat the magnetic iron oxide particles with the coupling agent in the aqueous medium, a method of stirring an appropriate amount of the magnetic iron oxide particles and the coupling agent in the aqueous medium can be mentioned. For example, in a mixer having a stirring blade (specifically, a high shear force mixing device such as an attritor or a TK homomixer), the magnetic powder particles are sufficiently made to become primary particles in an aqueous medium. Is good.

  The surface-treated magnetic iron oxide particles obtained in this way have no aggregation of particles and the surface of each particle is uniformly hydrophobized, so when used as a material for polymerized toner, Dispersibility is very good. Moreover, there is no exposure from the surface of the toner particles, and a polymer toner that is almost spherical can be obtained.

  The magnetic powder used in the present invention preferably uses 10 to 200 parts by mass with respect to 100 parts by mass of the binder resin. More preferably, 20 to 180 parts by mass are used. If it is less than 10 parts by mass, the coloring power of the toner is poor, and it is difficult to suppress fogging. On the other hand, when the amount exceeds 200 parts by mass, not only the retention by the magnetic force on the toner carrier is increased and the developability is lowered, but it is difficult not only to uniformly disperse the magnetic powder into individual toner particles, but also the fixability. May fall.

  The toner of the present invention may use other known colorants other than the magnetic powder. Known colorants include pigments and pigments that can be used. These colorants may be used alone or in combination of two or more. Moreover, it is preferable that 1-20 mass parts is used for the addition amount of coloring agents other than these magnetic powders with respect to 100 mass parts of binder resin, and when less than 1 mass part, coloring power will run short, 20 If the amount is more than part by mass, the fixability may deteriorate.

  Examples of the colorant other than the magnetic powder include, in addition to nigrosine dye / pigment, carbon black, and the like, the following cyan colorant, magenta colorant, and yellow colorant.

  As the cyan colorant, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66 and the like can be used particularly preferably.

  As the yellow colorant, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, allylamide compounds, and the like are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168, 180, etc. are preferably used.

  As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds, and the like are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48; 2, 48; 3, 48; 4, 57; 1, 81; 1, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254 are particularly preferred.

  These colorants may be those having a hydrophobic surface as in the case of the magnetic powder.

  Although the toner of the present invention can be produced by a pulverization method, it is more convenient and preferable to obtain the toner of the present invention by a polymerization method. When the toner of the present invention is obtained by a polymerization method, a polymerizable composition containing at least the resin for the toner of the present invention, a polymerizable monomer, a wax and a colorant is granulated in water, and a polymerization initiator is used. Can be obtained by suspension polymerization. Examples of polymerizable monomers that can be used in this case include styrene, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, and acrylic acid. 2-ethylhexyl, stearyl acrylate, 2-chloroethyl acrylate, acrylic esters such as phenyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacrylic acid Methacrylates such as n-octyl, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and other acrylics Nitrile, methacrylonitrile, are arbitrarily selected from monomers of acrylamide.

  Examples of the polymerization initiator that can be used include peroxide polymerization initiators, azo polymerization initiators, and the like. Use of a peroxide polymerization initiator is preferred because a more stable toner can be easily obtained. Used for. Examples of the peroxide polymerization initiator that can be used include peroxyesters, peroxydicarbonates, dialkyl peroxides, peroxyketals, ketone peroxides, hydroperoxides, diacyl peroxides, and inorganic ones. Examples of the system include persulfate and hydrogen peroxide. Specifically, t-butyl peroxyacetate, t-butyl peroxylaurate, t-butyl peroxypivalate, t-butyl peroxy- 2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxyneodecanoate, t-hexylperoxyacetate, t-hexylperoxylaurate, t-hexylperoxypivalate, t -Hexylperoxy-2-ethylhexanoate, t- Xylperoxyisobutyrate, t-hexylperoxyneodecanoate, t-butylperoxybenzoate, α, α'-bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, 1, 1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate Ate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxyisopropyl monocarbonate , T-butyl peroxyisopropyl monocarbonate, t-butyl -Oxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxy-m-toluoylbenzoate, bis (t-butylperoxy) Oxy) isophthalate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, 2,5-dimethyl-2,5-bis (m-toluoylperoxy) Peroxyesters such as hexane; diacyl peroxides such as benzoyl peroxide, lauroyl peroxide and isobutyryl peroxide; peroxydicarbons such as diisopropyl peroxydicarbonate and bis (4-t-butylcyclohexyl) peroxydicarbonate Ne 1,1-di-t-butylperoxycyclohexane, 1,1-di-t-hexylperoxycyclohexane, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, , 2-di-t-butylperoxybutane and other peroxyketals; di-t-butyl peroxide, dicumyl peroxide and t-butylcumyl peroxide and other dialkyl peroxides; A monocarbonate etc. are mentioned. Examples of the azo polymerization initiator that can be used include 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.

  If necessary, two or more of these polymerization initiators can be used simultaneously.

  The polymerization initiator used in the present invention is a polymer having a maximum between 10,000 and 50,000 when the polymerization reaction is carried out at an addition amount of 0.5 to 20 parts by weight with respect to 100 parts by weight of the monomer. To give the toner a desired strength and suitable melting characteristics.

  The toner according to the present invention preferably has an endothermic peak at 40 to 110 ° C., more preferably 45 to 90 ° C. when the temperature is increased, in the DSC curve of the toner measured by a differential scanning calorimeter.

  The toner image transferred onto the transfer material is then fixed on the transfer material with energy such as heat and pressure to obtain a semi-permanent image. At this time, heat roll type fixing is generally used.

  If toner with a volume average particle size of 10 μm or less is used, a very high-definition image can be obtained. However, toner particles with a small particle size can enter the gaps in the paper fibers when a transfer material such as paper is used. Further, heat reception from the heat fixing roller becomes insufficient, and low temperature offset is likely to occur.

  However, if the toner is designed to have an endothermic peak in the range of 40 to 110 ° C. in the DSC curve of the toner measured by a differential scanning calorimeter when the temperature is raised, the photosensitivity is achieved while achieving both high resolution and offset resistance. It becomes possible to prevent the body from being scraped. When the endothermic peak of the toner is less than 40 ° C., there may be a problem in storage stability and chargeability. When the endothermic peak is greater than 110 ° C., it is difficult to prevent the photoconductor from being scraped. There is.

  In a DSC curve of a toner measured by a differential scanning calorimeter, there are various methods for expressing an endothermic peak in the range of 40 to 110 ° C. when the temperature is raised. This can easily be achieved by using known waxes as part of the raw material.

  Note that the endothermic peak temperature of toner and wax is measured according to “ASTM D 3418-8”. For the measurement, for example, DSC-7 manufactured by PerkinElmer 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, an empty pan is set as a control, and measurement is performed at a heating rate of 10 ° C./min. Further, the glass transition temperature (Tg) of the binder resin component or the like can also be measured by the measuring device.

  Examples of the wax usable in the toner of the present invention include petroleum waxes such as paraffin wax, microcrystalline wax, petrolactam and derivatives thereof, montan wax and derivatives thereof, hydrocarbon waxes and derivatives thereof according to the Fischer-Tropsch method, and polyethylene. Polyolefin waxes and derivatives thereof, natural waxes such as carnauba wax and candelilla wax and derivatives thereof, and the derivatives include oxides, block copolymers with vinyl monomers, and graft modified products. Furthermore, fatty acids such as higher aliphatic alcohols, stearic acid, palmitic acid, or compounds thereof, acid amide waxes, ester waxes, ketones, hydrogenated castor oil and derivatives thereof, plant waxes, animal waxes, etc. In any case, the endothermic peak in the differential thermal analysis is preferably 40 to 110 ° C, more preferably 45 to 90 ° C.

  The wax used in the toner of the present invention preferably has a content in the range of 0.5 to 50 parts by mass with respect to 100 parts by mass of the binder resin. If the content is less than 0.5 parts by mass, the effect of suppressing low temperature offset is not sufficient, and if it exceeds 50 parts by mass, the long-term storage stability is deteriorated and the dispersibility of other toner materials is deteriorated. It may lead to deterioration of fluidity and deterioration of image characteristics.

  The average circularity of the toner of the present invention is preferably 0.970 or more.

  A toner having an average circularity of 0.970 or more is very excellent in transferability. This is presumably because the contact area between the toner particles and the photoconductor is small, and the adhesion force of the toner particles to the photoconductor due to mirror image force, van der Waals force, or the like is reduced.

  When the toner of the present invention contains magnetic iron oxide particles as a magnetic toner and the average circularity is 0.970 or more, the toner forms a thin spike at the developing portion because the circularity is very high, By making the charging of each magnetic toner uniform, a good image with very little fogging can be obtained.

  At this time, the mode circularity is more preferably 0.99 or more in the circularity distribution of the toner. When the mode circularity is 0.99 or more, it means that most of the toner particles have a shape close to a true sphere, and the transferability is further improved.

The average circularity and the mode circularity in the present invention are used as an index for quantitatively expressing the shape of the particles. In the present invention, the flow type particle image analyzer “FPIA-1000” manufactured by Toa Medical Electronics is used. Then, the circularity (ai) of the measured particles is obtained by the following formula (I), and the total roundness of all the particles measured as shown by the following formula (II) is calculated as the total number of particles (m ) Is defined as the average circularity (am).
Circularity (ai) = L0 / L Formula (I)
(In the formula, L0 represents the perimeter of a circle having the same projected area as the dry toner particle image, and L represents the perimeter of the dry toner particle projected image.)

  The mode circularity is a circularity of 0.40 to 1.00, 0.400 or more and less than 0.410, 0.410 or more and less than 0.420, ... 0.990 or more and 1 This is the peak circularity at which the frequency value is maximum in the circularity frequency distribution by dividing 61 parts every 0.01, such as less than .000 and 1.000, and assigning the measured circularity to each divided range. .

  In addition, "FPIA-1000" 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 of 0.40 to 1.. A calculation method is used in which 00 is divided into 61 classes, and the average circularity is calculated using the center value and frequency of the division points. However, there is very little error between each value of the average circularity calculated by this calculation method and each value of the average circularity calculated by the above-described calculation formula that directly uses the circularity of each particle. In the present invention, the calculation formula directly using the circularity of each particle described above is used for reasons of data handling such as shortening the calculation time and simplifying the calculation formula. Such a calculation method that is partially changed using the concept may be used.

  The measurement procedure is as follows.

  A dispersion is prepared by dispersing about 5 mg of toner in 10 ml of water in which about 0.1 mg of a surfactant is dissolved. Ultrasonic waves (20 kHz, 50 W) are irradiated on the dispersion for 5 minutes, and the concentration of the dispersion is 5000. Measurement is performed with the above apparatus at 20,000 / μl, and the average circularity and mode circularity of a particle group having an equivalent circle diameter of 3 μm or more are obtained.

  The average circularity in the present invention is an index of the degree of unevenness of the toner, and indicates 1.000 when the toner is a perfect sphere, and the average circularity becomes smaller as the toner surface shape becomes more complicated.

  In this measurement, the reason why the circularity is measured only for a particle group having an equivalent circle diameter of 3 μm or more is that particles of an external additive that exist independently of the toner particles in the particle group having an equivalent circle diameter of less than 3 μm This is because a large number of groups are included, and the circularity of the toner particle group cannot be accurately estimated due to the influence.

  In the present invention, as a method of setting the average circularity of the toner to 0.970 or more, a method of directly producing toner particles by the suspension polymerization method described above, in a solvent in which the monomer is dissolved but the resin is not dissolved. , A method of obtaining a spherical toner by a dispersion polymerization method in which a monomer is polymerized in the presence of a dispersion stabilizer, a method of spheroidizing toner particles produced by a pulverization method, a molten mixture or a solution of a toner raw material in air It can be achieved by various methods such as a method of producing a spherical toner by spraying inside. Among these toner production methods, the spray method is easy to obtain a spherical toner, but the particle size distribution of the obtained toner tends to be wide. On the other hand, in the dispersion polymerization method, a spherical toner can be easily obtained, and the obtained toner shows a very sharp particle size distribution. However, the selection of materials to be used is narrow, and the use of organic solvents makes it possible to treat waste solvents or remove solvents. From the viewpoint of flammability, the manufacturing apparatus is complicated and complicated. In addition, in the manufacturing method by smoothing and spheroidizing the pulverized toner, it is not always easy to set the average circularity to 0.970 or more. Decrease may occur. On the other hand, the method for producing the toner of the present invention by the suspension polymerization method is a particularly preferred production method because it is very easy to control the circularity and circularity standard deviation of the toner particles. In addition, in the case where the toner of the present invention contains magnetic iron oxide particles to form a magnetic toner, if magnetic iron oxide particles whose surface is uniformly hydrophobized are used as the toner material, the surface of the toner particles is substantially magnetic. Since it is easy to obtain a toner in which the iron oxide particles are not exposed and the magnetic iron oxide particles are encapsulated in the toner particles, the wear and wear of the members that come into contact with the toner, such as the photosensitive drum, the fixing roller, and the fixing film, are suppressed. In view of this, the suspension polymerization method is a particularly advantageous production method.

  In the image forming method of the present invention, in order to further develop finer latent image dots for higher image quality, the toner has a volume average particle diameter of 3 to 10 μm, more preferably 4 to 8 μm. preferable. In a toner having a volume 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 photoconductor scraping and toner fusion. In addition to increasing the surface area of the toner as a whole, the fluidity and stirrability of the powder decreases, so fogging and transferability tend to deteriorate, causing non-uniformity in images other than scraping and fusing. Since it is easy, it is not preferable for the toner used in the present invention.

  When the volume average particle diameter of the toner exceeds 10 μm, the characters and line images are likely to be scattered and it is difficult to obtain high resolution. Further, as the device becomes higher in resolution, toner of 8 μm or more tends to deteriorate the reproduction of one dot. In order to maintain more stable chargeability and developability, the volume average particle size of the toner is preferably 4 μm or more and 8 μm or less.

The coefficient of variation in the number distribution of the toner of the present invention is preferably 35% or less. If the coefficient of variation exceeds 35%, fusion to the surface of the photoreceptor, the toner layer thickness regulating member and the like is likely to occur, and image defects may occur. The variation coefficient S1 in the toner particle number distribution is calculated from the following equation (III).
Coefficient of variation S1 = (S / D1) × 100 Formula (III)
(In the formula, S represents a standard deviation value in the number distribution of toner particles, and D1 represents a number-average number average particle diameter (μm) obtained from the number distribution.)
Here, the volume average particle diameter, number average particle diameter, 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, a Coulter Multisizer (manufactured by Coulter) is connected to an interface (manufactured by Nikkiki) that outputs a number distribution and volume distribution, and a PC 9801 personal computer (manufactured by NEC). Use to prepare 1% NaCl aqueous solution. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolyte in which the sample is suspended is dispersed for about 1 to 3 minutes using an ultrasonic disperser, and the volume distribution is determined by measuring the volume and number of toner particles of 2 μm or more using the 100 μm aperture as the aperture by the Coulter Multisizer. And the number distribution.

  Then, the volume-based volume average particle diameter obtained from the volume distribution according to the present invention (D4: the median value of each channel is the representative value of the channel), and the number-based number average particle diameter obtained from the number distribution ( D1) and the number variation coefficient (S1) can be obtained. The same measurement can be performed in the present embodiment described later.

  In the present invention, when magnetic particles are contained in toner particles and used as a magnetic toner, the equivalent diameter of the projected area of the magnetic toner particles is C, and the magnetic powder particles in cross-sectional observation of the toner using a transmission electron microscope (TEM) When the minimum distance from the toner surface is D, the number of toner particles satisfying the relationship of D / C ≦ 0.02 is preferably 50% or more, more preferably 65% or more, and 75% or more. Is more preferable.

  When the number of toner particles satisfying the relationship of D / C ≦ 0.02 is less than 50%, at least the majority of toner particles have magnetic powder particles outside the boundary line of D / C = 0.02. Will not. In this case, assuming that the toner particles are spherical, at least 11.5% of the space where the magnetic powder particles do not exist when one toner particle is the entire space is present on the surface side of the toner particles. . Actually, the magnetic powder particles are not uniformly arranged at the closest position so as to form an inner wall inside the toner particles, so that it is obvious that it becomes 12% or more. In the magnetic toner composed of such particles, various problems as described above are likely to occur.

  In the present invention, as a specific method for measuring D / C by TEM, particles to be observed can be sufficiently dispersed in a room temperature curable epoxy resin and then cured in an atmosphere at a temperature of 40 ° C. for 2 days. The cured product is preferably observed as it is or as a flaky sample with a microtome equipped with diamond teeth after freezing.

  A specific method for determining the ratio of the number of corresponding particles is as follows.

  Particles for determining D / C by TEM are obtained by calculating the equivalent circle diameter from the cross-sectional area in the micrograph, and the value included in the width of ± 10% of the number average particle diameter is the corresponding particle. For the corresponding particles, the minimum value (D) of the distance between the magnetic powder particle surface and the magnetic toner particle surface is measured, and D / C is calculated. The ratio of particles having a D / C value calculated in this way of 0.02 or less is defined as being obtained by the following formula (IV). In this case, a magnification of 10,000 to 20,000 times is suitable for the microphotograph to perform highly accurate measurement.

  In the present invention, a transmission electron microscope (Hitachi model H-600) is used as an apparatus, observed at an accelerating voltage of 100 kV, and observed / measured using a microphotograph having a magnification of 10,000. The same measurement can be performed in the examples described later.

  In the present invention, in order for the number of toner particles satisfying the relationship of D / C ≦ 0.02 to be 50% or more, particles having a particle size in the range of 0.03 to 0.1 μm contained in the magnetic powder and 0. Examples thereof include reducing the ratio of particles having a particle diameter of 3 μm or more, and controlling the kind of surface treatment agent for magnetic powder and the uniformity of treatment.

In the present invention, when the magnetic particles are used as a magnetic toner in the toner particles, the magnetic toner has a magnetization intensity of 10 to 50 Am ² / kg (emu / mm) at a magnetic field of 79.6 kA / m (1000 oersted). g) is preferred.

  Magnetic toner can prevent leakage of toner by providing magnetic force generating means in the developing device, and can improve toner transportability or agitation. Further, by providing the magnetic force generating means so that the magnetic force acts on the toner carrying member, it becomes easy to prevent the toner from being scattered because the magnetic toner forms spikes.

  In the present invention, the reason why the strength of magnetization at a magnetic field of 79.6 kA / m is specified is that the amount of magnetization in magnetic saturation (saturated magnetization) is used as the quantity representing the magnetic characteristics of the magnetic powder. This is because the strength of magnetization of the magnetic toner in the magnetic field that actually acts on the magnetic toner in the image forming apparatus is important. When magnetic toner is applied to an image forming apparatus, the magnetic field acting on the magnetic toner is not limited to the leakage of the magnetic field to the outside of the image apparatus or in order to keep the cost of the magnetic field generation source low. In the image forming apparatus, a magnetic field of 79.6 kA / m (1000 oersted) is selected as a representative value of the magnetic field actually acting on the magnetic toner in the image forming apparatus. The strength of magnetization at 79.6 kA / m was defined.

As a means for obtaining such a magnetic toner, the toner particles may contain magnetic powder and the amount of magnetic powder added may be adjusted. When the strength of magnetization in the magnetic field of the toner of 79.6 kA / m is less than 10 Am ² / kg, the above effect cannot be obtained, and when the magnetic force is applied to the toner carrier, the rising of the toner becomes unstable. Image defects such as fog and uneven image density are likely to occur due to the fact that charging cannot be uniformly applied to the toner. When the magnetic toner has a magnetization intensity of 79.6 kA / m greater 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 aggregation, and the transferability is lowered. Since the amount of residual toner after transfer increases and the amount of magnetic powder contained in the toner particles is large, the fixability deteriorates.

  In the present invention, the toner is preferably produced by a polymerization method, particularly a suspension polymerization method. In this suspension polymerization method, the monomer resin composition of the present invention is prepared by uniformly dissolving or dispersing the resin for the toner, the polymerizable monomer, the colorant, the wax, and if necessary, the crosslinking agent and other additives. Then, the monomer composition is dispersed in an aqueous medium containing a dispersion stabilizer (for example, an aqueous phase) using an appropriate stirrer, and at the same time, a suspension polymerization reaction is performed using a polymerization initiator. A toner having a desired particle diameter is obtained. The polymerized toner obtained by this suspension polymerization method has individual toner particle shapes that are substantially spherical, so that the physical property requirement essential for the present invention that the circularity is 0.970 or more, and the mode circularity is 0. It is easy to obtain a toner satisfying more preferable physical properties of 99 or more, and such a toner has a high transferability because the distribution of charge amount is relatively uniform.

  By using the magnetic powder surface-treated with the above-mentioned coupling agent, the surface of the toner having a circularity of 0.970 or more, further a mode circularity of 0.99 or more, and measured by X-ray photoelectron spectroscopy analysis It is possible to obtain a magnetic toner having a ratio (B / A) of the content (B) of iron element to the content (A) of carbon element present in the toner. When used in the method, stabilization of high image quality can be achieved. Furthermore, if (B / A) is less than 0.0005, the image quality and durability stability are significantly improved.

  Next, a method for producing a polymerized toner according to the present invention by suspension polymerization will be described. In the production method of the polymerized toner, the toner particles are directly obtained by polymerizing the monomer composition containing the monomer.

  In the production of the polymerized toner according to the present invention, a resin may be added to the monomer composition composed of the polymerizable monomer for polymerization. Examples of the resin that can be used in this case include homopolymers of styrene such as polystyrene and polyvinyltoluene and substituted products thereof; styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene- Methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene-methacrylic acid Methyl copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether Copolymer, styrene Nylmethyl ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-maleic acid copolymers, styrene-maleic acid ester copolymers, and other styrene copolymers; polymethyl methacrylate, poly Butyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, silicone resin, polyester resin, polyamide resin, epoxy resin, polyacrylic acid resin, rosin, modified rosin, temper resin, phenol resin, aliphatic or alicyclic hydrocarbon Resins, aromatic petroleum resins and the like can be used alone or in combination.

  As addition amount of these resin, 1-20 mass parts is preferable with respect to 100 mass parts of monomers. 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 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.

  When the toner of the present invention is produced by a polymerization method, a crosslinking agent may be added, and the preferable addition amount is 0.001 to 5 parts by mass with respect to 100 parts by mass of the monomer.

  Here, as the crosslinking agent, a compound having two or more polymerizable double bonds is mainly used, for example, an aromatic divinyl compound such as divinylbenzene, divinylnaphthalene, etc .; for example, ethylene glycol diacrylate, ethylene glycol diester Carboxylic acid ester having two double bonds such as methacrylate, 1,3-butanediol dimethacrylate, etc .; Divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone, etc .; and having three or more vinyl groups Are used alone or as a mixture.

  When the toner of the present invention is produced by a polymerization method, generally, the above-described toner composition, that is, the resin for the toner of the present invention, a colorant, a wax, an optional cross-linking agent, and other additives are added to the polymerizable monomer. Add a suitable agent and suspend the monomer composition, which is uniformly dissolved or dispersed by a disperser such as a homogenizer, ball mill, colloid mill, or ultrasonic disperser, in an aqueous medium containing a dispersion stabilizer. To do. 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 all at once.

  When the toner is produced by a polymerization method, it is preferable to use a polymerization initiator. However, the timing of addition of the polymerization initiator may be added simultaneously with addition of other additives to the polymerizable monomer. Alternatively, it may be mixed immediately before being suspended in the aqueous medium. Also, 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.

  In addition, as the dispersion stabilizer used when the toner of the present invention is produced by a polymerization method, known surfactants and organic / inorganic dispersants can be used. Among them, when an inorganic dispersant is used, it causes image defects. The generation of ultrafine particles that can be reduced is suppressed, the dispersion stability is good even when the reaction temperature is changed, the washing is easy, and the toner is not adversely affected. 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.

  As for these inorganic dispersing agents, it is desirable to use 0.2-20 mass parts independently with respect to 100 mass parts of polymerizable monomers. Moreover, you may use 0.0001-0.1 mass part surfactant in combination with these inorganic dispersing agents.

  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.

  When the inorganic dispersant is used, a commercially available one may be used as it is, but fine particles of the inorganic dispersant may be produced in an aqueous medium and used as a dispersion stabilizer. 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 fine particles. Toner particles having a sharp particle size distribution are easily obtained in the range of 10 μm. At the same time, a water-soluble sodium chloride salt is by-produced at the same time. However, if a water-soluble salt is present in the aqueous medium, the dissolution of the polymerizable monomer in water is suppressed, and the submicron-size due to emulsion polymerization is suppressed. Since it becomes difficult to generate ultrafine particles, it is more convenient.

  In addition, when a dispersion stabilizer is used, it is desirable to remove the dispersant after the production of the toner, and if the dispersant remains on the toner surface, there may be a serious problem in chargeability, particularly environmental stability. Since there are many, it is preferable to remove as much as possible.

  For example, when tricalcium phosphate is used as a dispersant, tricalcium phosphate is added by adding an acid to the suspension after polymerization by utilizing the property of the dispersant being acidic and soluble in water. It is possible to remove the tricalcium phosphate almost completely by repeating dissolution and subsequent filtration and washing with water. When tricalcium phosphate is dissolved, tricalcium phosphate can be removed in a short time by setting the pH of the aqueous medium in which the toner particles are suspended to less than 4, more preferably less than 2. Examples of acids that can be used at this time include hydrochloric acid, nitric acid, and sulfuric acid.

  In the polymerization step, the polymerization is performed at a polymerization temperature of 40 ° C. or higher, generally 50 to 120 ° C. When the polymerization is carried out in this temperature range, the waxes to be sealed inside are preferably precipitated by phase separation and the encapsulation is more complete.

  The polymerized toner particles are filtered, washed, and dried by a known method after the polymerization is completed, and the toner can be obtained by mixing and adhering the inorganic fine powder 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.

  The toner of the present invention has inorganic fine powder on the surface of toner particles.

  The inorganic fine powder is added to and mixed with toner particles to improve the fluidity of the toner and make the charge uniform, and the added inorganic fine powder exists in a state of being uniformly attached to the surface of the toner particles.

  The inorganic fine powder in the present invention has a number average primary particle size of 4 to 80 nm. When the number average primary particle size of the inorganic fine powder is larger than 80 nm, or when the inorganic fine powder of 80 nm or less is not added, good toner fluidity cannot be obtained, and charging is imparted to the toner particles. Are likely to be non-uniform, and problems such as increased fog, decreased image density, and toner scattering may be unavoidable. When the number average primary particle size of the inorganic fine powder is smaller than 4 nm, the agglomeration of the inorganic fine powder is strengthened, and the aggregate is not a primary particle but an aggregate with a wide particle size distribution having a strong agglomeration property that is difficult to break even by crushing treatment. And image defects due to development of the aggregate, damage to the image carrier or development carrier, and the like. 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 to 35 nm.

  In the present invention, the number average primary particle size of the inorganic fine powder is measured by a photograph of the toner magnified by a scanning electron microscope, and further by an elemental analysis means such as XMA attached to the scanning electron microscope. Measure 100 or more primary particles of inorganic fine powder adhering to or leaving the toner particle surface while comparing photographs of toner mapped with the elements contained in the body, and determine the number average diameter. It is obtained by.

  As the inorganic fine powder used in the present invention, an inorganic fine powder selected from silica, alumina, titania or a double oxide thereof can be used. Examples of the double oxide of silica include silicate fine powder.

As the silicic acid fine powder, both so-called dry process 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. . Dry silica is preferred because it has few silanol groups on the surface and inside of the silicate fine powder and little production residue such as Na ₂ O, SO ₃ ^2- . 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. They are also included.

  The addition amount of the inorganic fine powder having a number average primary particle size of 4 to 80 nm is preferably 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the toner particles. If the addition amount is less than 0.1 parts by mass, the effect is not sufficient, and if it is 5.0 parts by mass or more, the fixability may be deteriorated.

  The inorganic fine powder in the present invention is added to improve the fluidity of the toner and to make the charge of the toner particles uniform. The adjustment of the charge amount of the toner and the environmental stability by a treatment such as a hydrophobic treatment of the inorganic fine powder. It is also a preferable form to provide a function such as improvement.

  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.

  Hydrophobizing agents for hydrophobizing inorganic fine powder include silicone varnish, various modified silicone varnishes, silicone oils, various modified silicone oils, silane compounds, silane coupling agents, other organic silicon compounds, and organic titanium compounds. You may process an agent individually or in combination.

  Among them, those treated with the above silicone oil are preferable, and more preferably, when the inorganic fine powder is treated with the silicone oil at the same time or after the hydrophobic treatment, the magnetic toner particles are used even in a high humidity environment. It is sufficient to keep the charge amount of the toner particles high and prevent toner scattering.

  As the treatment conditions for such inorganic fine powder, for example, a silylation reaction is carried out with the above-mentioned hydrophobization treatment agent as a first-stage reaction, and silanol groups are eliminated by chemical bonds, followed by a hydrophobization treatment. There is a method of forming a hydrophobic thin film on the surface with oil, whereby the hydrophobicity can be further increased. A more preferable treatment method includes a method in which a silane compound is used as a hydrophobizing treatment agent in the first stage reaction and a silicone oil treatment is used in the second stage reaction.

  As a method for treating the 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 silicone oil is sprayed onto the inorganic fine powder. A method may be used. Alternatively, after dissolving or dispersing silicone oil in a suitable 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 silicone oil preferably has a viscosity at 25 ° C. of 10 to 200,000 mm ² / s, and more preferably 3,000 to 80,000 mm 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 such silicone oil, 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.

  The treatment amount of the silicone oil is 1 to 23 parts by mass, preferably 5 to 20 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 may occur.

  Examples of the silane compound for treating the inorganic fine powder include organosilicon compounds such as hexamethyldisilazane.

The inorganic fine powder used in the present invention preferably has a specific surface area in the range of 20 to 300 m ² / g by nitrogen adsorption measured by the BET method.

  The specific surface area can be obtained by adsorbing nitrogen gas on the sample surface using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics) according to the BET method and calculating the specific surface area using the BET multipoint method. . The same measurement can be performed in the present embodiment described later.

The toner of the present invention has a primary particle size of more than 30 nm (preferably a specific surface area of less than 50 m ² / g), more preferably a primary particle size of 50 nm or more (preferably a specific surface area) for the purpose of improving cleaning properties. It is also a preferable form to add inorganic particles or organic particles close to a sphere having a particle size of less than 30 m ² / g). Specifically, for example, spherical silica particles, spherical polymethylsilsesquioxane particles, spherical resin particles and the like are preferably used.

  Further, the toner used in the present invention may further contain other additives, for example, a lubricant powder such as Teflon (registered trademark) powder, zinc stearate powder, polyvinylidene fluoride powder, or the like within a range that does not substantially adversely affect the toner. Development of abrasives such as cerium oxide powder, silicon carbide powder, strontium titanate powder, fluidity-imparting agents such as titanium oxide powder and aluminum oxide powder, anti-caking agent, and organic and / or inorganic fine particles of opposite polarity A small amount can be used as a property improver. These additives can also be used after hydrophobizing the surface.

<3> Image Forming Method Using Toner of the Present Invention The details thereof will be described below as an example of the image forming method of the present invention. The following image forming method includes a charging step, an electrostatic latent image forming step, a developing step, This is an example in which a magnetic toner containing a magnetic powder is used as the toner of the present invention. Embodiments of the image forming method of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

  In FIG. 1, a charging roller 117 as a contact charging member, a developing device 140 as a developing unit, a transfer roller 114 as a transfer unit, a cleaner 116, a register roller 124, and the like are provided around a photosensitive drum 100 as an image carrier. It has been. The photosensitive drum 100 is charged to −700 V by the charging roller 117. (Applied voltage is AC voltage -2.0 kVpp (Vpp: potential between peaks), DC voltage -700 Vdc), and the laser generator 121 irradiates the photosensitive drum 100 with laser light 123 for exposure. The electrostatic latent image on the photosensitive drum 100 is developed with a one-component magnetic toner by the developing device 140 and is transferred onto the transfer material by the transfer roller 114 in contact with the photosensitive drum via the transfer material. The transfer material on which the toner image is placed is conveyed to the fixing device 126 by the conveyance belt 125 or the like and fixed on the transfer material.

  In addition, toner partially remaining on the photosensitive drum is cleaned by a cleaner 116 as a cleaning unit. As shown in FIG. 2, the developing device 140 is provided with a cylindrical toner carrier 102 (hereinafter also referred to as “developing sleeve”) made of a nonmagnetic metal such as aluminum or stainless steel in the vicinity of the photosensitive drum 100. The gap between the photosensitive drum 100 and the developing sleeve 102 is maintained at about 300 μm by a sleeve / photosensitive member gap holding member (not shown). This gap can be changed if necessary. A magnet roller 104 is fixed and disposed concentrically with the developing sleeve 102 in the developing sleeve 102. However, the developing sleeve 102 is rotatable. The magnet roller 104 is provided with a plurality of magnetic poles, as shown in the figure, where S1 influences development, N1 restricts the amount of toner coating, S2 takes in / conveys toner, and N2 affects toner blowout prevention.

  The toner is applied to the developing sleeve 102 and adhered and conveyed. An elastic blade 103 is provided as a toner layer thickness regulating member that regulates the amount of magnetic toner to be conveyed, and the amount of toner conveyed to the development region is controlled by the contact pressure of the elastic blade 103 against the developing sleeve 102. In the developing area, a developing bias having a DC voltage and an AC voltage is applied between the photosensitive drum 100 and the developing sleeve 102, and the toner on the developing sleeve 102 flies onto the photosensitive drum 100 in accordance with the electrostatic latent image and is visible. It becomes.

  As an example of the developing method using the toner of the present invention, a system in which the toner carrier and the electrostatic image carrier are not in contact will be described.

  In the non-contact developing method, magnetic toner is applied on the toner carrier at a thickness smaller than the closest distance (between S and D) between the toner carrier and the photoreceptor (electrostatic charge image carrier). Development is performed by applying an electric field. That is, the layer thickness regulating member for regulating the magnetic toner on the toner carrying member sets the toner layer thickness on the toner carrying member to be smaller than the closest gap between the photoreceptor and the toner carrying member. At this time, the layer thickness regulating member for regulating the magnetic toner on the toner carrying member is an elastic member, and it is particularly preferable from the viewpoint of uniformly charging the magnetic toner to be in contact with the toner carrying member via the toner.

  Further, it is preferable that the toner carrying member is disposed to face the photosensitive member with a separation distance of 100 to 1000 μm, and is preferably disposed to face the photosensitive member with a separation distance of 120 to 500 μm. preferable. If the separation distance of the toner carrier from the photosensitive member is smaller than 100 μm, the change in the development characteristics of the toner with respect to the fluctuation of the separation distance becomes large, making it difficult to mass-produce an image forming apparatus that satisfies stable image quality. . If the distance between the toner carrier and the photosensitive member is larger than 1000 μm, the followability of the toner with respect to the latent image on the photosensitive member is deteriorated, leading to deterioration in image quality such as lower resolution and lower image density. There is a tendency to end up.

In the present invention, the toner carrier is preferably laminated so as to form a toner layer of 5 to 50 g / m ² . If the amount of toner on the toner carrier is less than 5 g / m ^2, it is difficult to obtain a sufficient image density, and the toner layer becomes uneven due to excessive charging of the toner. When the amount of toner on the toner carrier exceeds 50 g / m ² , toner scattering tends to occur.

  The surface roughness Ra (JIS centerline average roughness) of the toner carrier used in the present invention is preferably in the range of 0.2 to 3.5 μm. When Ra is less than 0.2 μm, the amount of charge on the toner carrier increases, and the developability tends to be insufficient. On the other hand, when Ra exceeds 3.5 μm, unevenness of toner stacking on the toner carrier is likely to occur, resulting in uneven density on the image. The surface roughness Ra is more preferably in the range of 0.5 to 3.0 μm.

  In the present invention, the surface roughness Ra of the toner carrier is measured using a surface roughness measuring device (Surfcoder SE-30H, manufactured by Kosaka Laboratory Co., Ltd.) based on JIS surface roughness “JIS B 0601”. This corresponds to the centerline average roughness. Specifically, a 2.5 mm portion as the measurement length a is extracted from the roughness curve in the direction of the center line, the center line of this extraction portion is the X axis, the direction of the vertical magnification is the Y axis, and the roughness curve is y When expressed by = f (x), the value obtained by the following formula (V) is expressed in micrometers (μm).

  As the toner carrier having a surface roughness (Ra) in the above range, a conductive cylinder formed of a metal or alloy such as aluminum or stainless steel is preferably used. A conductive cylinder may be formed of a resin composition having sufficient mechanical strength and conductivity, or a conductive rubber roller may be used. Further, the present invention is not limited to the cylindrical shape as described above, and may be an endless belt that is rotationally driven. Moreover, the resin layer may be used for these as a coating layer.

  In order to make the surface roughness (Ra) of the toner carrier in the present invention within the above range, for example, it is possible to change the polishing state of the surface layer of the toner carrier. That is, if the surface of the toner carrier is roughened, the surface roughness can be increased, and if the surface is finely polished, the surface roughness can be reduced.

  Further, when a resin layer is used, the surface roughness can be adjusted also by adding conductive fine particles and the like, which will be described later, to the resin layer, and the particle size and addition amount.

  Furthermore, since the magnetic toner according to the present invention has a high charging ability, it is preferable to control the total charge amount of the toner during development.

  The surface of the toner carrier according to the present invention is preferably coated with a resin layer in which conductive fine particles and / or a lubricant are dispersed.

  As the conductive fine particles contained in the resin layer covering the surface of the toner carrier, conductive metal oxides such as carbon black, graphite, and conductive zinc oxide, and metal double oxides are used alone or in combination of two or more. Is preferred. Examples of the resin in which the conductive fine particles and / or the lubricant are dispersed include phenol resins, epoxy resins, polyamide resins, polyester resins, polycarbonate resins, polyolefin resins, silicone resins, fluorine resins, styrene resins. Known resins such as resins and acrylic resins are used. A thermosetting resin or a photocurable resin is particularly preferable.

  In the non-contact developing method, it is preferable that the moving speed of the toner carrying member that carries the toner in the developing process and transports it to the developing unit is different from the moving speed of the photosensitive member. By providing such a speed difference, toner particles can be sufficiently supplied from the toner carrying member side to the photosensitive member side, and a good image can be obtained.

  In the present invention, the surface of the toner carrier that carries the toner may move in the same direction as the moving direction of the image carrier surface, or may move in the opposite direction. When the moving direction is the same direction, it is desirable that the ratio is 70% or more with respect to the moving speed of the image carrier. If it is less than 70%, the image quality may be poor. The higher the moving speed ratio, the more toner is supplied to the development site, the more frequently the toner is desorbed from the latent image, and the unnecessary parts are scraped off and applied to the necessary parts. Thus, an image faithful to the latent image can be obtained. Specifically, the moving speed of the toner carrier surface is preferably 0.7 to 7.0 times the moving speed of the image carrier surface.

In the developing unit, an AC electric field is applied in order to transfer the magnetic toner to an electrostatic latent image and develop it. At this time, the AC electric field has at least a peak-to-peak electric field strength of 3 × 10 ⁶ to. 1 × 10 ⁷ V / m and a frequency of 100 to 5000 Hz are preferable. It is also a preferred form that a DC bias is further superimposed.

  Next, the charging process will be described.

  In the present invention, a non-contact charging step such as a charging step using a charging device using corona discharge may be used, but a contact charging method in which a charging member is brought into contact with the photosensitive member is a preferable charging method. In this case, it is preferable to use a charging roller as the contact charging member.

  As a preferable process condition when using the charging roller as shown in FIG. 1, the contact pressure of the roller member is 4.9 to 490 N / m (5 to 500 g / cm), and the DC voltage or the DC voltage is changed to the AC voltage. Is used. In the case of using a DC voltage superimposed with an AC voltage, AC voltage = 0.5 to 5 kVpp, AC frequency = 50 to 5 kHz, and DC voltage = ± 0.2 to ± 5 kV are preferable.

  Other charging means include a method using a charging blade and a method using a conductive brush. Even when these contact charging means are used, there is an effect that a high voltage becomes unnecessary and generation of ozone is reduced.

  The material of the charging roller and charging blade as the contact charging member is preferably conductive rubber, and a release coating may be provided on the surface thereof. As the releasable coating, nylon resin, PVdF (polyvinylidene fluoride), PVdC (polyvinylidene chloride), and fluorine acrylic resin are applicable.

  Furthermore, by providing a relative speed difference between the moving speed of the surface of the charging member forming the contact portion and the moving speed of the surface of the image carrier, higher contact is achieved at the contact portion between the contact charging member and the image carrier. You can get sex.

  The contact charging member and the image carrier are preferably moved in the opposite directions at the contact portion. For example, it is desirable that the contact charging member is driven to rotate, and the rotation direction of the contact charging member is rotated in the direction opposite to the moving direction of the image carrier surface at the contact portion.

  Although it is possible to move the charging member in the same direction as the moving direction of the surface of the image carrier, a difference in speed is possible, but the contact charging property depends on the ratio between the peripheral speed of the image carrier and the peripheral speed of the charging member. In order to obtain the same peripheral speed ratio as that in the reverse direction, the rotation speed of the charging member in the forward direction is larger than that in the reverse direction. Therefore, it is advantageous in terms of the rotation speed to move the charging member in the reverse direction. The peripheral speed ratio described here can be expressed by the following formula (VI).

  The charging bias applied to the contact charging member can obtain good chargeability only with a DC voltage, but an AC voltage (alternating voltage) may be superimposed on the DC voltage as in the above-described apparatus shown in FIG.

  The alternating voltage at this time preferably has a peak voltage of less than 2 × Vth (Vth: discharge start voltage when a DC voltage is applied) (V).

  If the peak voltage of the AC voltage applied to the DC voltage is not less than 2 × Vth, the potential on the image carrier may become unstable. The AC voltage when applying a bias in which an AC voltage is superimposed on the DC voltage is more preferably a peak voltage less than Vth. As a result, the image carrier can be charged without a substantial discharge phenomenon.

  Next, the transfer process will be described.

  In the present invention, a non-contact transfer step such as a transfer step using a transfer device using corona discharge may be used, but preferably the transfer member is in contact with the photoconductor via a transfer material. This is a contact transfer method in which transfer is performed by the above method.

  The contact pressure of the transfer member is preferably 2.9 N / m (3 g / cm) or more, more preferably 19.6 N / m (20 g / cm) or more. If the linear pressure as the contact pressure is less than 2.9 N / m, it is not preferable because transfer of the transfer material and transfer failure are likely to occur.

Further, as a transfer member in the contact transfer process, an apparatus having a transfer roller or a transfer belt is used. As an example of the transfer roller, it is composed of at least a core metal and a conductive elastic layer, and the conductive elastic layer is an elastic body having a volume resistance of about 10 ⁶ to 10 ¹⁰ Ωcm, such as urethane or EPDM in which a conductive material such as carbon is dispersed. The transfer bias is applied by a transfer bias power source.

  Next, the photoreceptor used in the present invention will be described below.

As the photoreceptor, a photosensitive drum or a photosensitive belt having a photoconductive insulating material layer such as a-Se, CdS, ZnO ₂ , OPC (organic photoreceptor), or a-Si is preferably used.

In particular, in the present invention, it is preferable to use a photoreceptor whose surface is composed mainly of a polymer binder. For example, when a protective film (protective layer) mainly composed of a resin is provided on an inorganic photoreceptor such as selenium or amorphous silicon, or a surface comprising a charge transport material and a resin as a charge transport layer of a function-separated organic photoreceptor When a layer is provided, a protective layer mainly composed of resin may be provided on the surface layer. These surface layers (or protective layers) preferably have releasability, and as means for actually imparting releasability,
(1) Use a resin having a low surface energy as the resin constituting the film.
(2) Add additives that impart water repellency and lipophilicity,
(3) Means such as dispersing a material having high releasability in powder form. An example of (1) is the introduction of a functional group such as a fluorine-containing group or a silicone-containing group into the structure of the structural unit of the resin. Examples of the additive (2) that imparts water repellency and lipophilicity include surfactants. Examples of the material having high releasability (3) include compounds containing fluorine atoms, that is, polytetrafluoroethylene, poly (vinylidene fluoride), and fluorocarbon.

  By these means, the contact angle of water on the surface of the photoreceptor can be 85 degrees or more, and the transferability of toner and the durability of the photoreceptor can be further improved. The contact angle of the photoreceptor surface with water is preferably 90 degrees or more. In the present invention, among the above means (1) to (3), it is preferable to disperse in the outermost surface layer of a releasable powder such as a fluorine-containing resin as in (1). As the conductive powder, it is particularly preferable to use polytetrafluoroethylene.

  In order to contain these releasable powders on the surface, a layer in which the releasable powders are dispersed in a binder resin is provided on the outermost surface of the photoconductor, or the photoconductor itself is mainly composed of resin. In the case of a configured organic photoreceptor, a releasable powder may be dispersed in the uppermost layer without newly providing a surface layer. The addition amount of the releasable powder is preferably 1 to 60% by mass and more preferably 2 to 50% by mass with respect to the total amount of the surface layer. If the amount of the release powder added is less than 1% by mass, the effect of improving the transferability of the toner and the durability of the photoreceptor is insufficient, and if it exceeds 60% by mass, the strength of the protective film is reduced, This is not preferable because the amount of light incident on the body is significantly reduced.

  The contact angle is measured using a drop-type contact angle meter (for example, contact angle meter CA-X type manufactured by Kyowa Interface Science Co., Ltd.) where the free surface of water is in contact with the photoconductor. It is defined by the angle formed by the surface (the angle inside the liquid). In addition, the said measurement shall be performed at room temperature (about 21-25 degreeC).

  In the present invention, the contact charging method in which the charging unit abuts the charging member on the photosensitive member is a preferable charging method, and the load on the surface of the photosensitive member is different from the method using corona discharge in which the charging unit does not contact the photosensitive member. Therefore, providing a protective layer (protective film) on the surface of the photoreceptor has a remarkable effect of improving durability, and is one of the preferred application forms.

  In the present invention, since it is preferable to apply a contact charging method or a contact transfer method, a photoreceptor having a small diameter of 50 mm or less is particularly effectively used. That is, when the diameter of the photoconductor used in image formation is small, the curvature with respect to the same linear pressure is large, and pressure concentration tends to occur at the contact portion. Although it is considered that the same phenomenon occurs in the belt photoreceptor, the present invention is also effective for an image forming apparatus having a radius of curvature of 25 mm or less at the transfer portion.

  One preferred embodiment of the photoreceptor used in the present invention will be described below. Specifically, a laminated photosensitive layer having a structure in which a charge generation layer and then a charge transport layer are laminated in this order on a conductive substrate is one preferred example.

  As the conductive substrate, metal such as aluminum and stainless steel, aluminum alloy, plastic with a coating layer of indium oxide-tin oxide alloy, paper impregnated with conductive particles, plastic, plastic with conductive polymer, cylindrical shape Cylinders and films are used.

  On these conductive substrates, the adhesion of the photosensitive layer is improved, the coating property is improved, the substrate is protected, the defects on the substrate are coated, the charge injection from the substrate is improved, and the photosensitive layer is protected from electrical breakdown. For the purpose, an undercoat layer may be provided.

  Undercoat layer is polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, casein, polyamide, copolymer nylon, glue, gelatin, polyurethane It is made of a material such as aluminum oxide. The thickness of the undercoat layer is usually 0.1 to 10 μm, preferably about 0.1 to 3 μm.

  The charge generation layer is composed of azo pigments, phthalocyanine pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, squarylium dyes, pyrylium salts, thiopyrylium salts, triphenylmethane dyes, selenium, amorphous silicon, etc. A charge generating material such as an inorganic material is dispersed in a suitable binder resin and coated, or is formed by vapor deposition. Examples of the binder resin include polycarbonate resin, polyester resin, polyvinyl butyral resin, polystyrene resin, acrylic resin, methacrylic resin, phenol resin, silicon resin, epoxy resin, and vinyl acetate resin. A binder resin can be arbitrarily selected. The amount of the binder resin contained in the charge generation layer is preferably 80% by mass or less, and more preferably 0 to 60% by mass with respect to the entire charge generation layer. The film thickness of the charge generation layer is preferably 5 μm or less, particularly preferably 0.05 to 2 μm.

  The charge transport layer has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them. The charge transport layer is formed by dissolving a charge transport material in a solvent together with a binder resin, if necessary, and coating. The thickness of the charge generation layer is generally 5 to 40 μm. Examples of the charge transport material include polycyclic aromatic compounds having a structure such as biphenylene, anthracene, pyrene, and phenanthrene in the main chain or side chain, nitrogen-containing cyclic compounds such as indole, carbazole, oxadiazole, and pyrazoline, hydrazone compounds, Examples include styryl compounds, selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide.

  In addition, as a binder resin for dispersing these charge transport materials, polycarbonate resin, polyester resin, polymethacrylic acid ester, polystyrene resin, acrylic resin, polyamide resin, and other organic materials such as poly-N-vinylcarbazole and polyvinyl anthracene are used. A photoconductive polymer is mentioned.

  Furthermore, you may provide a protective layer separately as a surface layer. As the resin for the protective layer, polyester, polycarbonate, acrylic resin, epoxy resin, phenol resin, or curing agents for these resins can be used alone or in combination of two or more.

  In the present invention, the latent image forming means for forming an electrostatic latent image on the charging surface of the image carrier is preferably an image exposure means. The image exposure means for forming the electrostatic latent image is not limited to the laser scanning exposure means for forming a digital latent image, and other light emitting elements such as normal analog image exposure and LEDs may be used. It does not matter as long as it can form an electrostatic latent image corresponding to image information, such as a combination of a light emitting element such as a fluorescent lamp and a liquid crystal shutter.

  Further, the image carrier may be an electrostatic recording dielectric or the like. In this case, the dielectric surface is uniformly primary-charged to a predetermined polarity and potential, and then selectively neutralized by a neutralizing means such as a static elimination needle head or an electron gun to write and form a target electrostatic latent image.

  EXAMPLES Hereinafter, although a manufacture example and an Example demonstrate this invention concretely, this does not limit this invention at all.

<1> Production of Magnetic Powder Surface-treated magnetic powder A and magnetic powder B were obtained as follows.

<Production of surface-treated magnetic powder A>
In a ferrous sulfate aqueous solution, 1.0 to 1.1 equivalents of caustic soda solution with respect to iron element, 1.0 wt% sodium hexametaphosphate with respect to iron element in terms of phosphorus element, silicon element with respect to iron element Was mixed with 1.0 wt% sodium silicate to prepare an aqueous solution containing ferrous hydroxide. Air was blown in while maintaining the pH of the aqueous solution at around 13, and an oxidation reaction was performed at 80 to 90 ° C. 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 ₁₀ H _{21 was} thoroughly stirred. 1.0 part by mass of Si (OCH ₃ ) ₃ ) was added to the magnetic iron oxide particles (the amount of magnetic iron oxide particles was calculated as a value obtained by subtracting the water content from the water-containing sample), and a coupling treatment was performed. Then, the produced hydrophobic magnetic iron oxide particles were washed with water, filtered and dried with hot air at 40 ° C., and then the slightly agglomerated particles were crushed to obtain surface-treated magnetic powder A.

<Manufacture of magnetic powder B>
In the same way as the production of the surface-treated magnetic powder A, the oxidation reaction proceeds, the magnetic iron oxide particles generated after the oxidation reaction are washed, filtered, dried without surface treatment, and the aggregated particles are crushed. Magnetic powder B was obtained.

<2> Manufacture of Toner Resin <Manufacture of Toner Resin A>
A 2 L flask equipped with a stirrer, a condenser, a thermometer, and a nitrogen introduction tube was charged with 400 g of methanol, 300 g of toluene, and 500 g of methyl ethyl ketone, and refluxed under a nitrogen stream. A mixture of 6 g of methyl methacrylate, 30 g of 2-acrylamido-2-methylpropanesulfonic acid, 42 g of n-butyl acrylate, 48 g of stearyl methacrylate, 474 g of styrene and 18 g of azobisisobutyronitrile was added dropwise with stirring. Hold for 10 hours. Thereafter, distillation was performed to distill off the solvent, and the residue was transferred to a stainless steel vat and dried at 50 ° C. under reduced pressure. The obtained solid was pulverized to produce Resin A for Toner of the present invention.

<Manufacture of Resin B for Toner>
Similar to the production of Resin A for toner, except that the monomer component is changed to 15 g of methyl methacrylate, 30 g of 2-acrylamido-2-methylpropanesulfonic acid, 48 g of n-butyl acrylate, 60 g of stearyl methacrylate, and 447 g of styrene. The toner resin B of the present invention was obtained.

<Manufacture of toner resin C>
A toner resin C of the present invention was obtained in the same manner as in the production of the toner resin B except that 2-acrylamido-2-methylpropanesulfonic acid was replaced with sulfooctylacrylic acid.

<Manufacture of Resin D for Toner>
Similar to the production of Resin A for toner, except that the monomer component is changed to 5 g of methyl methacrylate, 57 g of 2-acrylamido-2-methylpropanesulfonic acid, 15 g of n-butyl acrylate, 21 g of stearyl methacrylate, and 502 g of styrene. Thus, a resin D for toner of the present invention was obtained.

<Manufacture of Resin E for Toner>
Similar to the production of Resin A for toner, except that the monomer component is changed to 5 g of methyl methacrylate, 57 g of 2-acrylamido-2-methylpropanesulfonic acid, 50 g of n-butyl acrylate, 75 g of stearyl methacrylate, and 413 g of styrene. Thus, resin E for toner of the present invention was obtained.

<Manufacture of resin F for toner>
The toner resin F of the present invention was obtained in the same manner as in the production of the toner resin A except that the amount of azobisisobutyronitrile added was changed from 18 g to 4 g.

<Manufacture of Resin G for Toner>
Similar to the production of Resin A for toner, except that the monomer component is changed to 3 g of methyl methacrylate, 57 g of 2-acrylamido-2-methylpropanesulfonic acid, 60 g of n-butyl acrylate, 54 g of stearyl methacrylate, and 426 g of styrene. Thus, a resin G for toner of the present invention was obtained.

<Manufacture of Resin H for Toner>
Similar to the production of Resin A for toner, except that the monomer component is changed to 30 g of methyl methacrylate, 30 g of 2-acrylamido-2-methylpropanesulfonic acid, 40 g of n-butyl acrylate, 72 g of stearyl methacrylate, and 428 g of styrene. Thus, the toner resin H of the present invention was obtained.

<Manufacture of Resin I for Toner>
Similar to the production of Resin A for toner, except that the monomer component is changed to 45 g of methyl methacrylate, 15 g of 2-acrylamido-2-methylpropanesulfonic acid, 40 g of n-butyl acrylate, 72 g of stearyl methacrylate, and 428 g of styrene. The toner resin I of the present invention was obtained.

<Manufacture of toner resin J>
Similar to the production of Resin A for toner, except that the monomer component is changed to 30 g of methyl methacrylate, 30 g of 2-acrylamido-2-methylpropanesulfonic acid, 30 g of n-butyl acrylate, 195 g of n-butyl methacrylate, and 315 g of styrene. Thus, the resin J for toner of the present invention was obtained.

<Manufacture of Resin K for Toner>
Similar to the production of Resin A for toner, except that the monomer component is replaced with 80 g of methyl methacrylate, 21 g of 2-acrylamido-2-methylpropanesulfonic acid, 48 g of n-butyl acrylate, 151 g of n-butyl methacrylate, and 300 g of styrene. Thus, the resin K for toner of the present invention was obtained.

<Manufacture of resin L for toner>
A comparative toner resin L was obtained in the same manner as in the production of the toner resin A except that the monomer component was changed to 30 g of sulfooctylacrylic acid, 168 g of n-butyl acrylate, and 402 g of styrene.

<Manufacture of Resin M for Toner>
Toner resin for comparison in the same manner as in the production of toner resin A, except that the monomer component is replaced with 0.6 g of methyl methacrylate, 29.4 g of sulfooctylacrylic acid, 168 g of n-butyl acrylate, and 402 g of styrene. M was obtained.

<Manufacture of Resin N for Toner>
A comparative toner resin N was obtained in the same manner as in the production of the toner resin A except that the monomer component was replaced with 26 g of methyl methacrylate, 4 g of sulfooctylacrylic acid, 145 g of n-butyl acrylate, and 425 g of styrene. .

  Table 1 shows the physical properties of the toner resins A to N.

<3> Manufacture of magnetic toner <Manufacture of magnetic toner A>
To 292 parts by mass of ion-exchanged water, 46 parts by mass of 1.0 M Na ₃ PO ₄ aqueous solution was added and heated to 80 ° C., and then 67 parts by mass of 1.0 M CaCl ₂ aqueous solution was gradually added to form Ca _3. An aqueous medium containing (PO ₄ ) ₂ was obtained.
-Styrene 82 parts by mass-2-ethylhexyl acrylate 18 parts by mass-Saturated polyester resin 10 parts by mass-Unsaturated polyester resin 2 parts by mass-Resin A for toner of the present invention 5 parts by mass-Surface-treated magnetic powder A 90 parts by mass The prescription was uniformly dispersed and mixed using an attritor (Mitsui Miike Chemical Co., Ltd.) to obtain a monomer composition. This monomer composition was heated to 80 ° C., and 12 parts by mass of ester wax having an endothermic peak temperature in differential thermal analysis of 75 ° C. was added and mixed therewith, and 6 parts by mass of benzoyl peroxide as a polymerization initiator was added thereto. Dissolved.

The monomer composition was put into the aqueous medium, and the mixture was granulated by stirring at 10,000 rpm for 10 minutes in a TK homomixer (Special Machine Industries Co., Ltd.) in an N ₂ atmosphere at 80 ° C. . Then, while stirring with a paddle stirring blade, the mixture was reacted at 80 ° C. for 4 hours, and 4 parts by mass of anhydrous sodium carbonate was added to the system. Thereafter, the system was depressurized to -50 KPa and distilled for 4 hours. After completion of the distillation, the suspension was cooled, and the alkaline suspension was filtered. Next, washing of the toner particles with water was repeated three times to obtain a hydrated magnetic toner. Thereafter, the water-containing magnetic toner was added to 1000 parts by mass of dilute hydrochloric acid (pH 1.0) at room temperature while stirring, and stirring was continued for 3 hours. Further, this suspension was filtered, and the toner was washed with water five times. Thereafter, the hydrated magnetic toner was dried with hot air at 40 ° C. for 3 days to obtain magnetic toner particles A having a volume average particle diameter of 7.2 μm.

A Henschel mixer (100 parts by mass of the magnetic toner particles A) and 1 part by mass of hydrophobic silica fine powder having a number average particle diameter of 9 nm and BET of 180 m ² / g, the surface of which was treated with hexamethyldisilazane and then treated with silicone oil. (Mitsui Miike Chemical Co., Ltd.) to obtain magnetic toner A. Table 2 shows the physical properties of the magnetic toner A.

<Manufacture of magnetic toner B>
Magnetic toner B was prepared in the same manner as magnetic toner A except that the amount of resin A for toner of the present invention was changed from 5 parts to 0.5 parts. Table 2 shows the physical properties of Magnetic Toner B.

<Manufacture of magnetic toner C>
A magnetic toner C was prepared in the same manner as the magnetic toner A except that the amount of the resin A for toner of the present invention was changed from 5 parts to 15 parts. Table 2 shows the physical properties of the magnetic toner C.

<Manufacture of magnetic toner D>
A magnetic toner D was prepared in the same manner as the magnetic toner A except that the toner resin B of the present invention was used instead of the toner resin A of the present invention. Table 2 shows the physical properties of the magnetic toner D.

<Manufacture of magnetic toner E>
A magnetic toner E was prepared in the same manner as the magnetic toner A except that the toner resin C of the present invention was used in place of the toner resin A of the present invention. Table 2 shows the physical properties of the magnetic toner E.

<Manufacture of magnetic toner F>
A magnetic toner F was prepared in the same manner as the magnetic toner A except that the toner resin D of the present invention was used instead of the toner resin A of the present invention. Table 2 shows the physical properties of the magnetic toner F.

<Manufacture of magnetic toner G>
A magnetic toner G was prepared in the same manner as the magnetic toner A except that the toner resin E of the present invention was used instead of the toner resin A of the present invention. Table 2 shows the physical properties of the magnetic toner G.

<Manufacture of magnetic toner H>
A magnetic toner H was prepared in the same manner as the magnetic toner A except that the toner resin F of the present invention was used in place of the toner resin A of the present invention. Table 2 shows the physical properties of the magnetic toner H.

<Manufacture of magnetic toner I>
A magnetic toner I was prepared in the same manner as the magnetic toner A except that the toner resin G of the present invention was used in place of the toner resin A of the present invention. Table 2 shows the physical properties of the magnetic toner I.

<Manufacture of magnetic toner J>
A magnetic toner J was prepared in the same manner as the magnetic toner A except that the toner resin H of the present invention was used in place of the toner resin A of the present invention. Table 2 shows the physical properties of the magnetic toner J.

<Manufacture of magnetic toner K>
A magnetic toner K was prepared in the same manner as the magnetic toner A except that the toner resin I of the present invention was used instead of the toner resin A of the present invention. Table 2 shows the physical properties of the magnetic toner K.

<Manufacture of magnetic toner L>
A magnetic toner K was prepared in the same manner as the magnetic toner A except that the toner resin J of the present invention was used in place of the toner resin A of the present invention. Table 2 shows the physical properties of the magnetic toner L.

<Manufacture of magnetic toner M>
A magnetic toner K was prepared in the same manner as the magnetic toner A except that the toner resin K of the present invention was used in place of the toner resin A of the present invention. Table 2 shows the physical properties of the magnetic toner M.

<Manufacture of magnetic toner N>
Magnetic toner N was obtained in the same manner as in the production of magnetic toner A, except that the amount of ester wax used was 0.4 parts by mass. Table 2 shows the physical properties of the magnetic toner N.

<Manufacture of magnetic toner O>
Magnetic toner O was obtained in the same manner as in the production of magnetic toner A, except that the amount of ester wax used was 51 parts by mass. Table 2 shows the physical properties of the magnetic toner O.

<Manufacture of magnetic toner P>
Magnetic toner P was obtained in the same manner as in the production of magnetic toner A, except that 12 parts by mass of low molecular weight polyethylene wax having an endothermic peak temperature of 110 ° C. in differential thermal analysis was used instead of ester wax. Table 2 shows the physical properties of the magnetic toner P.

<Manufacture of magnetic toner Q>
Magnetic toner Q was obtained in the same manner as in the production of magnetic toner A, except that the amount of surface-treated magnetic powder A used was 50 parts by mass. Table 2 shows the physical properties of the magnetic toner Q.

<Manufacture of magnetic toner R>
A magnetic toner R was obtained in the same manner as in the production of the magnetic toner A except that the amount of the surface-treated magnetic powder A was 150 parts by mass. Table 2 shows the physical properties of the magnetic toner R.

<Manufacture of magnetic toner S>
369.5 g of PO adduct of bisphenol A, 146.4 g of EO adduct of bisphenol A, 126.0 g of terephthalic acid, 40.2 g of dodecenyl succinic acid and 77.7 g of trimellitic anhydride are added to a 2-liter 4-neck flask made of glass. A thermometer, a stainless steel stirring bar, a condenser, and a nitrogen introducing tube were attached, and the reaction was carried out at 220 ° C. under a nitrogen stream in a mantle heater. The degree of polymerization was tracked from the softening point according to ASTM E28-67, and the reaction was terminated when the softening point reached 110 ° C. The polyester was then purified by reprecipitation and vacuum dried at 50 ° C. for 3 days.

  Next, 65 parts by mass of styrene, 35 parts by mass of 2-ethylhexyl acrylate, 0.25 parts by mass of divinylbenzene (purity 99% or more), 12 parts by mass of ester wax having an endothermic peak of 75 ° C., 98 parts by mass of surface-treated magnetic powder A In addition, 10 parts by mass of the polyester resin synthesized above, 5 parts by mass of the resin A for toner of the present invention, and 5 parts by mass of benzoyl peroxide are added to an attritor and dispersed at 10 ° C. for 5 hours. A polymerizable composition was obtained.

  Next, 212.3 g of the polymerizable composition is added to 650 g of an aqueous colloidal solution of 4% by mass of tricalcium phosphate prepared in advance in a 2 liter glass separable flask and brought to room temperature using a TK homomixer. And granulated for 2 minutes at a rotational speed of 10,000 rpm.

  Next, a four-necked glass lid was capped, and a reflux condenser, a thermometer, a nitrogen inlet tube, and a stainless steel stirring rod were attached and installed in an electric heating mantle heater. While stirring under nitrogen, the temperature was raised to 80 ° C. as the first stage polymerization, and reacted for 5 hours to obtain seed particles. This was cooled to room temperature to obtain precursor particles. Next, 13 parts by mass of styrene prepared by an ultrasonic oscillator in the aqueous suspension of the precursor particles, 7 parts by mass of 2-ethylhexyl acrylate, 1 part by mass of benzoyl peroxide, 0.10 parts by mass of divinylbenzene, A water emulsion composed of 0.1 parts by mass of sodium lauryl sulfate, 10 parts by mass of sodium carbonate, and 20 parts by mass of water was added dropwise to swell the precursor particles. Then, while continuing stirring under nitrogen, the temperature was raised to 85 ° C. as the second stage polymerization, and the reaction was allowed to proceed for 10 hours. The suspension was cooled and the alkaline suspension was filtered. Next, washing of the toner particles with water was repeated three times to obtain a hydrated magnetic toner. Thereafter, the water-containing magnetic toner was added to 1000 parts by mass of dilute hydrochloric acid (pH 1.0) at room temperature while stirring, and stirring was continued for 3 hours. Further, this suspension was filtered, and the toner was washed with water five times. Thereafter, the water-containing magnetic toner was dried with hot air at 40 ° C. for 3 days to obtain magnetic toner particles S having a volume average particle size of 7.6 μm.

  100 parts by mass of the magnetic toner particles S and 1 part by mass of hydrophobic silica fine powder used in the production of the magnetic toner A were mixed with a Henschel mixer to obtain the magnetic toner S. Table 2 shows the physical properties of the magnetic toner S.

  <Manufacture of Magnetic Toner T> 200 parts by weight of xylene was placed in a reaction vessel and heated to the reflux temperature. A solution mixture of 82 parts by mass of styrene, 18 parts by mass of 2-ethylhexyl acrylate, and 3.0 parts by mass of di-tert-butyl peroxide was added dropwise thereto, and the solution polymerization was completed in 7 hours under reflux of xylene. A molecular weight resin solution was obtained.

  On the other hand, 82 parts by mass of styrene, 18 parts by mass of 2-ethylhexyl acrylate, 2 parts by mass of t-butylperoxy-2-ethylhexanoate, 0.2 parts by mass of polyvinyl alcohol, and 200 parts by mass of deaerated water were mixed and suspended. Turbidly dispersed. The suspension dispersion was heated and held at 80 ° C. for 24 hours under a nitrogen atmosphere to complete the polymerization, thereby obtaining a high molecular weight resin.

  25 parts by weight of the high molecular weight resin is put into the solution at the end of the solution polymerization containing 75 parts by weight of the low molecular weight resin, completely dissolved in the solvent and mixed, and then the solvent is distilled off to form a solution. A resin (1) was obtained.

When the binder resin (1) was analyzed, the low molecular weight side peak molecular weight was 9000, the high molecular weight side peak molecular weight was 870000, the weight average molecular weight (Mw) was 400,000, and the number average molecular weight (Mn) was 52,000.
-Binder resin (1) 100 parts by weight-Saturated polyester resin 12 parts by mass-Toner resin A 5 parts by mass of the present invention-Magnetic powder B 90 parts by mass-Ester wax used in the production of magnetic toner A 12 parts by mass The above materials are mixed in a blender, melt kneaded with a biaxial extruder heated to 140 ° C., the cooled kneaded product is coarsely pulverized with a hammer mill, and the coarsely pulverized product is finely pulverized with a jet mill. The pulverized product was subjected to air classification to obtain magnetic toner particles T having a volume average particle size of 7.6 μm. A magnetic toner T was prepared by mixing a mixture of 1 part by mass of hydrophobic silica used in the production of the magnetic toner A with 100 parts by mass of the magnetic toner particles R using a Henschel mixer. Table 2 shows the physical properties of the magnetic toner T.

<Manufacture of magnetic toner U>
In the production of the magnetic toner T, toner particles were obtained by the same method except that the coarsely pulverized product was finely pulverized with a turbo mill (manufactured by Turbo Kogyo Co., Ltd.). Thereafter, magnetic toner particles U having a volume average particle diameter of 7.8 μm and subjected to spheronization treatment were obtained using an impact surface treatment apparatus (treatment temperature 50 ° C., rotary treatment blade peripheral speed 90 m / sec.).

  Next, a mixture obtained by adding 1 part by mass of hydrophobic silica used in the production of the magnetic toner A to 100 parts by mass of the obtained spherical toner particles T is mixed with a Henschel mixer, and magnetically mixed. Toner U was prepared. Table 2 shows the physical properties of the magnetic toner U.

<Manufacture of magnetic toner V>
A comparative magnetic toner V was obtained in the same manner as in the production of the magnetic toner A, except that the toner resin L was used instead of the toner resin A, and the magnetic powder B was used instead of the surface-treated magnetic powder A. Table 2 shows the physical properties of the magnetic toner V.

<Manufacture of magnetic toner W>
A comparative magnetic toner W was obtained in the same manner as in the production of the magnetic toner A, except that the toner resin M was used instead of the toner resin A, and the magnetic powder B was used instead of the surface-treated magnetic powder A. Table 2 shows the physical properties of the magnetic toner W.

<Manufacture of magnetic toner X>
A comparative magnetic toner X was obtained in the same manner as in the production of the magnetic toner A, except that the toner resin N was used instead of the toner resin A, and the magnetic powder B was used instead of the surface-treated magnetic powder A. Table 2 shows the physical properties of the magnetic toner X.

<Manufacture of magnetic toner Y>
A comparative magnetic toner Y was obtained in the same manner as in the production of the magnetic toner T, except that the toner resin L was used instead of the toner resin A, and the magnetic powder B was used instead of the surface-treated magnetic powder A. Table 2 shows the physical properties of the magnetic toner Y.

<Manufacture of magnetic toner Z>
In the production of the magnetic toner Y, toner particles were obtained by the same method except that the coarsely pulverized product was finely pulverized with a turbo mill (manufactured by Turbo Kogyo Co., Ltd.). Thereafter, a comparative magnetic toner Z having a volume average particle diameter of 7.7 μm and subjected to spheronization treatment was obtained using an impact surface treatment apparatus (treatment temperature 50 ° C., rotary treatment blade peripheral speed 90 m / sec.). Table 2 shows the physical properties of the magnetic toner Z.

Incidentally, the intensity of magnetization in a magnetic field 79.6 kA / m of the resulting magnetic toner, the magnetic toner Q is 18.0Am ² / kg, the magnetic toner R was 35.8Am ² / kg, other magnetic toner All were 26-30 Am < ² > / kg.

<4> Manufacture of photoconductor <Manufacture of photoconductor A>
As a photoreceptor, an aluminum cylinder having a diameter of 30 mm was used as a base. 3A and 3B were sequentially laminated by dip coating to prepare a photoreceptor A.
(1) The first layer is a conductive coating layer (conductive layer) mainly composed of a powder of tin oxide and titanium oxide dispersed in a phenol resin. Film thickness 15 μm.
(2) The second layer is an undercoat layer and is mainly composed of modified nylon and copolymer nylon. Film thickness 0.6 μm.
(3) The third layer is a charge generation layer mainly composed of an azo pigment having absorption in a long wavelength region dispersed in a butyral resin. Film thickness 0.6 μm.
(4) The fourth layer is a charge transport layer mainly composed of a hole-transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight of 20,000 by the Ostwald viscosity method) at a mass ratio of 8:10. 10 mass% of fluorinated ethylene powder (volume average particle size 0.2 μm) was added to the total solid content and dispersed uniformly. Film thickness 25 μm. The contact angle with water was 95 degrees.

  The contact angle was measured using pure water, and the device used was Kyowa Interface Science Co., Ltd., contact angle meter CA-X type.

<5> Image forming method using magnetic toner (Examples 1 to 21 and Comparative Examples 1 to 5)
As an image forming apparatus, LBP-1760 (manufactured by Canon Inc.) was remodeled, and an apparatus generally shown in FIG. 1 was used.

  A photoreceptor A (an organic photoreceptor (OPC) drum) was used as the photoreceptor 100 as an image carrier. A charging roller 117 in which conductive carbon is dispersed and coated with nylon resin as a charging member is brought into contact with the photoreceptor 100 (contact pressure 60 g / cm), and an AC voltage of 1.8 kVpp is superimposed on a DC voltage of −700 Vdc. The applied bias is applied to uniformly charge the photosensitive member. Subsequent to charging, the electrostatic latent image is formed by exposing the image portion with laser light. At this time, the dark portion potential Vd = −700 V and the bright portion potential VL = −160 V.

As the toner carrier, a developing sleeve 102 having a resin layer having a layer thickness of about 6 μm and a JIS center line average roughness (Ra) 0.7 μm formed on an aluminum cylinder having a diameter of 16 mm blasted on the surface is used. A development rubber pole of 90 mT (900 gauss) and a urethane rubber blade having a thickness of 1.5 mm and a free length of 0.5 mm as a toner regulating member were brought into contact at a linear pressure of 29.4 N / m (30 g / cm). The gap between the photoreceptor 100 and the developing sleeve 102 was 280 μm.
・ Phenolic resin 100 parts by mass ・ Graphite (volume average particle size of about 7 μm) 90 parts by mass ・ Carbon black 10 parts by mass Next, a DC voltage of −480 V, a frequency of 1900 Hz, and an AC voltage of 1700 V between peaks were superimposed as a developing bias. A thing was used. The peripheral speed of the developing sleeve was 110% (110 mm / sec) in the forward direction with respect to the peripheral speed of the photosensitive member (100 mm / sec).

As the transfer means, a transfer roller 34 as shown in FIG. 4 (volume resistance value of conductive elastic layer 34b made of ethylene-propylene rubber in which conductive carbon is dispersed, 1 × 10 ⁸ Ω · cm, surface rubber hardness is used. 24 degrees, a diameter of 20 mm, a contact pressure of 59 N / m (60 g / cm)) were set at a constant speed with respect to the peripheral speed of the photoreceptor (100 mm / sec), and a transfer bias was set to a DC voltage of 1.5 kV.

  As the fixing means, a fixing device of the type shown in FIG. 5 in which heat and pressure are fixed by a heater through a film having no oil application function is used. The pressure roller 33 is a roller having a diameter of 30 mm having a foam of silicone rubber as a lower layer and a surface layer of a fluororesin. The total pressure between the heating body 31 and the pressure roller 33 is 88.2 N (9 Kg). ) The nip between the pressure roller and the film is 7 mm, and the fixing film 32 has a low resistance release layer in which a conductive material is dispersed in PTEF (high molecular weight type) on the contact surface with the transfer material. A 50 μm heat-resistant polyimide film was used. The surface temperature of the temperature measuring element 31d of the heating body 31 was 190 ° C.

  Using magnetic toners A to U and comparative magnetic toners V to Z as developers, an image pattern consisting of only a vertical line with a printing area ratio of 5% in an environment of normal temperature and normal humidity (25 ° C., 60% RH). In the intermittent mode at a printout speed of 12 sheets / minute (A4 size) (that is, each time one sheet is printed out, the developer is stopped for a certain period of time, and the deterioration of the toner is promoted by the preliminary operation of the developing device at the time of restart. Mode) was performed (printing out a solid black image pattern with a printing area ratio of 100% and a solid white image pattern with a printing area ratio of 0% every 500 sheets).

  Next, after leaving the image forming apparatus in which the process cartridge is set in a low temperature and low humidity (15 ° C., 10% RH) environment for 3 days, an image pattern consisting only of vertical lines with a print area ratio of 2% is set to 5000 in the intermittent mode. A sheet printout test was conducted.

Note that 80 g / m ² of paper was used as the transfer material.

  Each toner was evaluated according to the criteria described below. The evaluation results are summarized in Table 3.

[Evaluation]
1) Image Density With a Macbeth reflection densitometer RD918 (manufactured by Macbeth Co.) on the 2000th and 4000th solid black printout images at room temperature and normal humidity, print a white background portion with a document density of 0.00. The relative density with respect to the out image was measured, the average value was calculated, and evaluated as follows.
A: Very good (above 1.40)
B: Good (less than 1.35 to 1.40)
C: Normal (less than 1.20 to 1.35)
D: Bad (less than 1.20)

2) Fog For the 2001 and 4001 solid white printout images at room temperature and humidity, measure the fog density (%) from the difference between the whiteness of the white area and the whiteness of the transfer paper. The average value was calculated and evaluated as follows. The whiteness was measured with a “reflectometer” (manufactured by Tokyo Denshoku Co., Ltd.).
A: Very good (less than 1.5%)
B: Good (1.5% or more, less than 2.5%)
C: Normal (2.5% or more, less than 4.0%)
D: Poor (4.0% or more)

3) Transferability The image forming apparatus is forcibly stopped during the formation of the 1000th and 5000th solid black images at room temperature and humidity, and the transfer residual toner on the photoconductor is taped with Mylar tape. The numerical values obtained by subtracting the Macbeth concentration of only the Mylar tape stuck on the paper from the Macbeth concentration of the peeled and peeled Mylar tape stuck on the paper were calculated and averaged, and evaluated as follows.
A: Very good (less than 0.05)
B: Good (less than 0.05 to 0.1)
C: Normal (less than 0.1-0.2)
D: Bad (over 0.2)

4) Fixability For the 1000th and 5000th solid black printout images in a low-temperature, low-humidity environment, a load of 50 g / cm ² was applied and the fixed image was rubbed with a soft thin paper before and after rubbing. The reduction rate (%) of the image density (Macbeth density) was calculated and the average value was calculated and evaluated as follows.
A: Very good (less than 5%)
B: Good (less than 5% to 10%)
C: Normal (10% to less than 20%)
D: Bad (more than 20%)

5) Rise of charging For the 1000th and 5000th solid black printout images in a low-temperature and low-humidity environment, the Macbeth reflection densitometer RD918 was used to calculate the relative density with respect to the printout image of the white background portion where the document density was 0.00. Each difference was measured and the difference was calculated and evaluated as follows.
A: Very good (less than 0.05)
B: Good (less than 0.05 to 0.1)
C: Normal (less than 0.1-0.2)
D: Bad (over 0.2)

6) Charging stability For the 1000th and 5000th solid white printout images at low temperature and low humidity, the fog density (%) was measured from the difference in whiteness of the white background and the whiteness of the transfer paper. The difference was calculated and evaluated as follows.
A: Very good (less than 0.3%)
B: Good (0.3% or more, less than 0.8%)
C: Normal (0.8% or more, less than 1.5%)
D: Poor (1.5% or more)

7) Inverted fog When 500 sheets were printed out at normal temperature and humidity, the development bias was temporarily changed to -380V. Next, the image forming apparatus was forcibly stopped during the formation of the solid white image, and the fog toner on the photosensitive member was removed by taping with a Mylar tape. The whiteness of the peeled mylar tape stuck on the paper and the whiteness of the mylar tape alone stuck on the paper were measured, and the fog density was calculated from the difference between these whitenesses. Similarly, after the printout of 5000 sheets, the development bias is changed to −380 V and the fog density is measured, and the fog density at the end of 500 printouts is subtracted from the fog density at the end of 5000 printouts. From the value, it evaluated as follows.
A: Very good (less than 0.5%)
B: Good (0.5% or more, less than 1.0%)
C: Normal (1.0% or more, less than 2.0%)
D: Poor (2.0% or more)

8) Gradation For the evaluation of gradation, 8 types of images with different pattern formation methods shown in FIG. 6 were printed out at normal temperature and humidity after completion of all printout tests, and the Macbeth reflection densitometer. Was determined by measuring the respective image densities.

From the viewpoint of gradation reproducibility, the density range of each pattern image is preferably the following range, and evaluation was performed from this viewpoint.
Pattern 1: 0.10 to 0.15 Pattern 2: 0.15 to 0.20
Pattern 3: 0.20 to 0.30 Pattern 4: 0.25 to 0.40
Pattern 5: 0.55-0.70 Pattern 6: 0.65-0.80
Pattern 7: 0.75 to 0.90 Pattern 8: 1.40 or more Judgment criteria are as follows.

A: Very good (all pattern images satisfy the above density range)
B: Good (one pattern image is out of the above density range)
C: Normal (two or three pattern images deviate from the above density range)
D: Poor (four or more pattern images deviate from the above density range)

[Matching evaluation with image forming device]
1) Matching with sleeve After all the printout tests were completed, the occurrence of scratches on the sleeve surface and the sticking of residual toner and the effect on the printout image were visually evaluated.
A: Not generated B: Scratches are slightly observed C: There are sticking and scratches D: There are many sticking

2) Matching with photoconductor After all the printout tests were completed, the occurrence of scratches on the surface of the photoconductor drum and the sticking of residual toner and the influence on the printout image were visually evaluated.
A: Not generated B: Scratches are slightly observed C: There are sticking and scratches D: There are many sticking

3) Matching with the fixing device After the completion of all the printout tests, the flaws on the surface of the fixing film and the fixing state of the residual toner were visually evaluated.
A: Not generated B: Slightly fixed C: Fixed or scratched D: Many fixed

<6> Manufacture of non-magnetic toner <Manufacture of non-magnetic toner α>
To 292 parts by mass of ion-exchanged water, 46 parts by mass of 1.0 M Na ₃ PO ₄ aqueous solution was added and heated to 80 ° C., and then 67 parts by mass of 1.0 M CaCl ₂ aqueous solution was gradually added to form Ca _3. An aqueous medium containing (PO ₄ ) ₂ was obtained.
-Styrene 82 parts by mass-2-ethylhexyl acrylate 18 parts by mass-Saturated polyester resin 10 parts by mass-Unsaturated polyester resin 2 parts by mass-Toner resin A 5 parts by weight of the present invention-Pigment Blue 15: 3 5 parts by mass Was uniformly dispersed and mixed using an attritor (Mitsui Miike Chemical Co., Ltd.) to obtain a monomer composition. This monomer composition was heated to 80 ° C., and 12 parts by mass of ester wax having an endothermic peak temperature in differential thermal analysis of 75 ° C. was added and mixed therewith, and 6 parts by mass of benzoyl peroxide as a polymerization initiator was added thereto. Dissolved.

The monomer composition was put into the aqueous medium, and the mixture was granulated by stirring at 10,000 rpm for 10 minutes in a TK homomixer (Special Machine Industries Co., Ltd.) in an N ₂ atmosphere at 80 ° C. . Then, while stirring with a paddle stirring blade, the mixture was reacted at 80 ° C. for 4 hours, and 4 parts by mass of anhydrous sodium carbonate was added to the system. Thereafter, the reaction was further continued for 4 hours, and then the suspension was cooled and the alkaline suspension was filtered. Next, washing of the toner particles with water was repeated three times to obtain a water-containing nonmagnetic toner. Thereafter, the water-containing non-magnetic toner was added to 1000 parts by mass of dilute hydrochloric acid (pH 1.0) at room temperature while stirring, and stirring was continued for 3 hours. Further, this suspension was filtered, and the toner was washed with water five times. Thereafter, the water-containing nonmagnetic toner was dried with hot air at 40 ° C. for 3 days to obtain nonmagnetic toner particles α.

100 parts by mass of this non-magnetic toner particle α and 1 part by mass of hydrophobic silica fine powder having a number average particle diameter of 9 nm and BET of 180 m ² / g, the surface of which was treated with hexamethyldisilazane and then treated with silicone oil, were added to a Henschel mixer. To obtain a non-magnetic toner α.

<Manufacture of non-magnetic toner β>
-Binder resin used in the production of magnetic toner T (1) 100 parts by weight-Saturated polyester resin 12 parts by mass-Toner resin L 5 parts by weight-Pigment Blue 15: 3 5 parts by mass-In the production of non-magnetic toner α 12 parts by weight of ester wax used The above materials were mixed in a blender, melt kneaded with a twin screw extruder heated to 140 ° C., the cooled kneaded product was coarsely pulverized with a hammer mill, and the coarsely pulverized product was finely pulverized with a turbo mill. did. Thereafter, non-magnetic toner particles β subjected to spheroidizing treatment were obtained using an impact surface treatment apparatus (treatment temperature 50 ° C., rotary treatment blade peripheral speed 90 m / sec.).

  Next, a mixture obtained by adding 1 part by mass of hydrophobic silica used in the production of the non-magnetic toner α to 100 parts by mass of the obtained non-magnetic toner particles β was mixed with a Henschel mixer. Non-magnetic toner β was prepared.

<7> Image forming method using non-magnetic toner (Example 22 and Comparative Example 6)
As an image forming apparatus, a commercially available color copying machine PIXEL L (manufactured by Canon) is used in a single color mode, and the nonmagnetic toner α of the present invention and the nonmagnetic toner β for comparison are used as developers, and evaluated as follows. I did it.

First, a non-magnetic toner was filled in a process cartridge, and a printout test was performed on 5000 image patterns consisting of only vertical lines with a printing area ratio of 5% in a normal temperature and normal humidity (25 ° C., 60% RH) environment. (A solid image pattern with a printing area ratio of 100% and a solid white image pattern with a printing area ratio of 0% were printed every 1000 sheets.) Next, in a low temperature and low humidity (15 ° C., 10% RH) environment. The image forming apparatus in which the process cartridge was set was allowed to stand for 3 days, and then a printout test was performed on 5000 image patterns consisting of only vertical lines with a printing area ratio of 2%. Note that 80 g / m ² of paper was used as the transfer material.

  Each toner was evaluated according to the criteria described below. The evaluation results are summarized in Table 5.

[Evaluation of printout image]
1) Image density With a Macbeth reflection densitometer RD918 (manufactured by Macbeth Co., Ltd.), a document density of 0.00 is printed on a printout image with a printing area ratio of 100% on the 2000th and 4000th sheets in a normal temperature and humidity environment. The relative density with respect to the printout image of the white background part was measured, the average value was calculated, and evaluated as follows.
A: Very good (above 1.40)
B: Good (less than 1.35 to 1.40)
C: Normal (less than 1.20 to 1.35)
D: Bad (less than 1.20)

2) Fog For the 2001 and 4001 solid white printout images at room temperature and humidity, measure the fog density (%) from the difference between the whiteness of the white area and the whiteness of the transfer paper. The average value was calculated and evaluated as follows. The fog density was measured with a “reflectometer” (manufactured by Tokyo Denshoku).
A: Very good (less than 1.5%)
B: Good (1.5% or more, less than 2.5%)
C: Normal (2.5% or more, less than 4.0%)
D: Poor (4.0% or more)

3) Transferability The image forming apparatus is forcibly stopped in the middle of forming a solid image with a printing area ratio of 100% on the 1000th sheet and 5000th sheet in a room temperature and humidity environment, Calculate the average value by measuring the numerical value obtained by subtracting the Macbeth concentration of only the Mylar tape that was pasted on the paper from the Macbeth concentration of the tape where the Mylar tape was taped and peeled off with the Mylar tape, and the following values were calculated. It was evaluated as follows.
A: Very good (less than 0.05)
B: Good (less than 0.05 to 0.1)
C: Normal (less than 0.1-0.2)
D: Bad (over 0.2)

4) Fixability For the 1000th and 5000th printout images in a low-temperature, low-humidity environment, a load of 50 g / cm ² was applied, the fixed image was rubbed with a soft thin paper, and the image density before and after rubbing. The rate of decrease (%) of (Macbeth concentration) was calculated and the average value thereof was calculated and evaluated as follows.
A: Very good (less than 5%)
B: Good (less than 5% to 10%)
C: Normal (10% to less than 20%)
D: Bad (more than 20%)

5) Rise of charging For a solid image with a printing area ratio of 100% on the 1000th sheet and the 5000th sheet in a low-temperature, low-humidity environment, a Macbeth reflection densitometer RD918 applies a printout image of a white background portion with a document density of 0.00. The relative concentration was measured and the difference was calculated and evaluated as follows.
A: Very good (less than 0.05)
B: Good (less than 0.05 to 0.1)
C: Normal (less than 0.1-0.2)
D: Bad (over 0.2)

6) Charging stability For the 1000th and 5000th solid white printout images at low temperature and low humidity, the fog density (%) was measured from the difference between the whiteness of the white background and the whiteness of the transfer paper. The difference was calculated and evaluated as follows.
A: Very good (less than 0.3%)
B: Good (0.3% or more, less than 0.8%)
C: Normal (0.8% or more, less than 1.5%)
D: Poor (1.5% or more)

7) Inverted fog When 500 sheets were printed out at normal temperature and humidity, the development bias was temporarily changed to -380V. Next, the image forming apparatus was forcibly stopped during the formation of the solid white image, and the fog toner on the photosensitive member was removed by taping with a Mylar tape. The whiteness of the peeled mylar tape stuck on the paper and the whiteness of the mylar tape alone stuck on the paper were measured, and the fog density was calculated from the difference between these whitenesses. Similarly, after the printout of 5000 sheets, the development bias is changed to −380 V and the fog density is measured, and the fog density at the end of 500 printouts is subtracted from the fog density at the end of 5000 printouts. From the value, it evaluated as follows.
A: Very good (less than 0.5%)
B: Good (0.5% or more, less than 1.0%)
C: Normal (1.0% or more, less than 2.0%)
D: Poor (2.0% or more)

8) Gradation For the evaluation of gradation, 8 types of images with different pattern formation methods shown in FIG. 6 were printed out at normal temperature and humidity after completion of all printout tests, and the Macbeth reflection densitometer. Was determined by measuring the respective image densities.

From the viewpoint of gradation reproducibility, the density range of each pattern image is preferably the following range, and evaluation was performed from this viewpoint.
Pattern 1: 0.10 to 0.15 Pattern 2: 0.15 to 0.20
Pattern 3: 0.20 to 0.30 Pattern 4: 0.25 to 0.40
Pattern 5: 0.55-0.70 Pattern 6: 0.65-0.80
Pattern 7: 0.75 to 0.90 Pattern 8: 1.40 or more Judgment criteria are as follows.

A: Very good (all pattern images satisfy the above density range)
B: Good (one pattern image is out of the above density range)
C: Normal (two or three pattern images deviate from the above density range)
D: Poor (four or more pattern images deviate from the above density range)
[Matching evaluation with image forming device]
1) Matching with sleeve After all the printout tests were completed, the occurrence of scratches on the sleeve surface and the sticking of residual toner and the effect on the printout image were visually evaluated.
A: Not generated B: Slightly scratched C: Fixed or scratched D: Many fixed 2) Matching with photoconductor After completion of all printout tests, scratches and residual toner on the surface of the photosensitive drum The occurrence of sticking and the effect on the printout image were visually evaluated.
A: Not generated B: Slight scratches are observed C: Fixed or scratched D: Many fixed 3) Matching with the fixing device After all printout tests are completed, scratches on the surface of the fixing roller and residual toner The state of fixation was visually evaluated.
A: Not generated B: Slightly fixed C: Fixed or scratched D: Many fixed

1 is a schematic configuration diagram showing an embodiment of an image forming apparatus of the present invention. It is a figure which shows the developing device shown in FIG. 1, and its periphery. It is a figure which shows a part of cross-sectional structure of the image carrier used for this invention. It is a figure which shows the transfer roller shown in FIG. 1, and its periphery. It is a figure which shows the fixing device of the system which heat-press-fixes with a heater through the film without the oil application function used in Examples 1-21 and Comparative Examples 1-5 of this invention. It is a figure which shows 8 types of image patterns used for evaluation of the gradation property in Examples 1-22 and Comparative Examples 1-6 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Photosensitive drum 102 Toner carrier 114 Transfer roller 116 Cleaner 117 Charging roller 121 Laser generator 123 Laser light 124 Register roller 125 Conveyor belt 126 Fixing device 140 Developer 141 Stirring member 103 Elastic blade 104 Magnet roller 34 Transfer roller 34a Core metal 34b Conductive elastic layer 35 Power supply for transfer bias 31 Heating element 31d Temperature sensing element 32 Fixing film 33 Pressure roller

Claims (39)

Copolymerize at least M1) methyl (meth) acrylate and M2) SO ₃ X (X represents one or more selected from H, Na, K, NH ₄ , Ca, Mg) group-containing polymerizable monomers A toner resin, wherein the mass ratio of M1 to M2 is from 5:95 to 80:20. The copolymer is at least M1) methyl (meth) acrylate, M2) SO ₃ X (X represents one or more selected from H, Na, K, NH ₄ , Ca, Mg) group-containing polymerizability Monomer, M3) styrene, and M4) a copolymer obtained by copolymerizing (meth) acrylic acid esters other than methyl (meth) acrylate, and having a glass transition temperature of 40 to 40 2. The toner resin according to claim 1, wherein the temperature is 110 ° C. and the mass ratios of M1, M2, M3, and M4 satisfy the following relationship.
M1: M2 = 5: 95-80: 20
(M1 + M2): M3 = 0.1: 99.9 to 20:80
(M1 + M2 + M3): M4 = 70: 30 to 95: 5 The SO ₃ X (X represents one or more selected from H, Na, K, NH ₄ , Ca, and Mg) group-containing polymerizable monomers are acrylamide-2-methylpropanesulfonic acid (salt), sulfo 3. One or more selected from alkyl (meth) acrylic acid (salt), allyl sulfonic acid (salt), vinyl sulfonic acid (salt), and styrene sulfonic acid (salt) The toner resin described in 1.   4. The toner resin according to claim 1, wherein a peak molecular weight calculated by gel permeation chromatography of a component soluble in tetrahydrofuran of the copolymer is 2000 to 50000. In a toner having toner particles containing at least a binder resin and a colorant and inorganic fine powder mixed with the toner particles, the toner includes at least M1) methyl (meth) acrylate and M2) SO ₃ X ( X represents one or more selected from H, Na, K, NH ₄ , Ca, and Mg) and is a copolymer obtained by copolymerizing a group-containing polymerizable monomer, And a copolymer obtained by copolymerizing at a mass ratio of 5:95 to 80:20. The copolymer is at least M1) methyl (meth) acrylate, M2) SO ₃ X (X represents one or more selected from H, Na, K, NH ₄ , Ca and Mg). A copolymer obtained by copolymerizing a monomer, M3) styrene, and M4) a (meth) acrylic acid ester other than methyl (meth) acrylate, and having a glass transition temperature of 40 to 110. 6. The toner according to claim 5, wherein the toner has a mass ratio of M1, M2, M3, and M4 satisfying the following relationship.
M1: M2 = 5: 95-80: 20
(M1 + M2): M3 = 0.1: 99.9 to 20:80
(M1 + M2 + M3): M4 = 70: 30 to 95: 5 The SO ₃ X (X represents one or more selected from H, Na, K, NH ₄ , Ca, and Mg) group-containing polymerizable monomers are acrylamide-2-methylpropanesulfonic acid (salt), sulfo 7. One or more selected from alkyl (meth) acrylic acid (salt), allyl sulfonic acid (salt), vinyl sulfonic acid (salt), and styrene sulfonic acid (salt) The toner according to any one of the above.   8. The toner according to claim 5, wherein a peak molecular weight calculated by gel permeation chromatography of a component soluble in tetrahydrofuran of the copolymer is 2000 to 50000.   9. The dry toner according to claim 5, wherein the content of the copolymer is 0.1 to 20 parts by mass with respect to 100 parts by mass of the toner.   The toner according to claim 5, wherein an average circularity of the toner is 0.970 or more.   The toner according to claim 5, wherein the mode circularity of the toner is 0.99 or more.   The toner according to claim 5, wherein the toner contains 0.5 to 50 parts by mass of wax with respect to 100 parts by mass of the binder resin.   13. The toner according to claim 5, wherein the toner has an endothermic peak in a range of 40 to 110 ° C. when the temperature is increased, in a DSC curve of the toner measured by a differential scanning calorimeter.   14. The toner according to claim 5, wherein the toner has an endothermic peak in a range of 45 to 90 ° C. when the temperature is increased, in a DSC curve of the toner measured by a differential scanning calorimeter.   The toner according to claim 13 or 14, wherein the toner particles of the toner further contain a wax, and the endothermic peak obtained by the differential thermal analysis is derived from the wax. The toner is a magnetic toner containing magnetic powder, the toner has a magnetization strength of 10 to 50 Am ² / kg at a magnetic field of 79.6 kA / m, and the inorganic toner adhering to the toner particle surface from the magnetic toner. The ratio of the amount of iron element (B) to the amount of carbon element (A) present on the surface of the magnetic toner particle in the measurement by X-ray photoelectron spectroscopy (ESCA) of the surface of the magnetic toner particle from which the fine powder has been removed. The toner according to claim 5, wherein (B / A) is less than 0.001.   When the diameter corresponding to the projected area of the magnetic toner particles is C, and D is the minimum distance between the magnetic powder particles and the toner surface in the cross-sectional observation of the toner using a transmission electron microscope (TEM), D / C The toner according to claim 16, wherein the toner satisfying the relationship of ≦ 0.02 is 50% by number or more.   The toner according to claim 5, wherein the magnetic toner contains 10 to 200 parts by mass of a magnetic powder with respect to 100 parts by mass of the binder resin.   The toner according to claim 5, wherein the inorganic fine powder is a hydrophobic fine inorganic powder having a number average primary particle size of 4 to 80 nm.   The inorganic fine powder has a number average primary particle size of 4 to 80 nm, and is at least one inorganic fine powder selected from silica, titanium oxide, and alumina or a double oxide thereof. The toner according to any one of 19.   The toner according to claim 5, wherein the inorganic fine powder is treated with at least silicone oil.   The toner according to any one of claims 5 to 21, wherein the inorganic fine powder is treated with silicone oil at the same time as or after the treatment with the silane compound.   A charging step of applying a voltage to the charging member to charge the image carrier, an electrostatic latent image forming step of forming an electrostatic latent image on the charged image carrier, and holding the electrostatic latent image on the surface A developing region is formed by disposing an image carrier to be carried and a toner carrier to carry toner on the surface, and in the development region, the dry toner is transferred to the electrostatic latent image to form a toner image. Image forming that has a development process formed on an image carrier and a transfer process in which a toner image formed on the image carrier is electrostatically transferred to a transfer material, and image formation is repeated on the image carrier In the method, the said toner is the toner as described in any one of Claims 5-22, The image forming method characterized by the above-mentioned.   The charging step is a contact charging member in which the charging member is in contact with the image carrier by forming a contact portion, and the image carrier is charged by applying a voltage to the contact charging member. The image forming method according to claim 23, characterized in that:   The charging step is a step of charging the image carrier with a relative speed difference between the moving speed of the surface of the contact charging member forming the contact portion and the moving speed of the surface of the image carrier. The image forming method according to claim 23 or 24.   The image forming according to any one of claims 23 to 25, wherein the charging step is a step of charging the image carrier while the contact charging member and the image carrier move in opposite directions. Method.   In the charging step, a DC voltage or an AC voltage having a peak-to-peak voltage less than 2 × Vth (Vth: discharge start voltage when DC voltage is applied) (V) is applied to the contact charging member. 27. The image forming method according to claim 23, wherein the image bearing member is charged by the step of charging.   The charging step is a step of charging the image carrier by applying a DC voltage or a voltage obtained by superimposing an AC voltage having a peak-to-peak voltage less than Vth (V) on the DC voltage to the contact charging member. The image forming method according to any one of claims 23 to 27, characterized in that:   29. The image forming method according to claim 23, wherein the image carrier is a photoconductor using a photoconductive substance.   30. The image forming method according to claim 23, wherein the electrostatic latent image forming step forms an electrostatic latent image on an image carrier by image exposure.   31. The developing step according to claim 23, wherein the moving speed of the toner carrier surface in the developing region is 0.7 to 7.0 times the moving speed of the image carrier surface. Image forming method.   32. The image forming method according to claim 23, wherein, in the developing step, the surface roughness (Ra) of the toner carrier is 0.2 to 3.5 [mu] m. In the developing step, the toner carried on the toner carrier, an image forming method according to any one of claims 23 to 32, characterized in that a toner layer of 5 to 50 g / m ^2.   34. The toner amount carried on the toner carrier is regulated by the toner layer thickness regulating member disposed in contact with the toner carrier in the developing step. The image forming method according to item.   35. The image forming method according to claim 34, wherein the toner layer thickness regulating member is an elastic member.   36. The developing step according to any one of claims 23 to 35, wherein the toner carried on the toner carrier has a thickness that is thinner than a gap between the image carrier and the toner carrier. The image forming method described.   37. In the developing step, the image carrier and the toner carrier are arranged so as to face each other with a predetermined gap, and the gap is 100 to 1000 μm. The image forming method according to one item. The developing step is a step of developing an electrostatic latent image on the image carrier with toner by applying at least an alternating electric field as a developing bias between the toner carrier and the image carrier. 38. The image forming method according to claim 23, wherein the peak electric field intensity is 3 × 10 ⁶ to 1 × 10 ⁷ V / m and the frequency is 100 to 5000 Hz.   The transfer step is a step in which the transfer member is in contact with the image carrier through the transfer material during transfer, and the toner image on the image carrier is transferred to the transfer material. The image forming method according to any one of the above.

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