JP2007086550A - Electrostatic charge image developing toner, electrostatic charge image developer, and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic charge image developing toner capable of effectively preventing the occurrence of photoreceptor contamination and flaws on a photoreceptor surface, suppressing an image quality defect for a long period, and providing excellent fixability and blocking resistance. <P>SOLUTION: The electrostatic charge image developing toner is characterized by containing porous silicon nitride fine powder of volume average grain size 50 to 200 nm and BET specific surface area 40 to 120 m<SP>2</SP>/g as an external additive on a toner base particle surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a toner for developing an electrostatic image used for developing an electrostatic image in an electrophotographic apparatus utilizing an electrophotographic process such as a copying machine, a printer, and a facsimile, and an electrostatic image developer using the same. The present invention relates to an image forming method.

  An electrophotographic method for visualizing image information through an electrostatic latent image (see, for example, Patent Document 1 or 2) is currently used in various fields. In the electrophotographic method, generally, an electrostatic latent image is formed on a photoreceptor in a charging / exposure process, and a toner image is formed by developing the electrostatic latent image using a developer containing toner in a developing process. In the transfer step, the toner image is transferred onto a transfer medium such as paper or sheet, and in the fixing step, the toner image is fixed on a transfer material using heat, solvent, pressure, or the like to obtain a permanent image. Is the method. Therefore, the toner needs to satisfy the required characteristics in each of these steps.

  In general, toner is subjected to stress or impact force due to contact with a charging member or other members in a developing machine during repeated copying, which may cause structural and characteristic deterioration and affect image quality. . Therefore, in order to ensure a reliable image quality over a long period of time, it is necessary to design a tough binder that can withstand mechanical impact force. Therefore, in many cases, it is conceivable to increase the molecular weight of the binder resin. However, a resin having a high molecular weight has a high softening temperature, which causes concern in the fixing process. That is, in the non-contact type fixing method such as oven fixing or radiant fixing, thermal efficiency is low and sufficient fixing ability cannot be expected. Even in the heat roller system with relatively good thermal efficiency, it is necessary to increase the temperature of the heat roller in order to sufficiently fix the toner, and the toner is strongly desired as the speed and size of recent copying machines increase. This greatly contradicts the low temperature fixability.

  On the other hand, a fixing method using a heat roller, or a fixing method in which one or both of the rolls are replaced with a belt as a similar technique, has a high thermal efficiency because the surface of the heat roller and the toner surface of the fixing member are in pressure contact, and is widely used. However, when the surface of the heat roller and the surface of the toner come into contact with each other, a so-called offset phenomenon may occur in which the toner adhering to the surface of the heat roller moves to a transfer member such as paper that is fed later. In general, the offset that occurs when paper or other material is not sufficiently fixed on the transfer material is called cold offset, and the offset that occurs when the toner on the transfer material is overheated is called hot offset. Since the lower limit temperature is between the cold offset and the hot offset, the actual fixable temperature range is between the fixing lower limit temperature and the hot offset, and the fixing lower limit temperature is lowered as much as possible to raise the hot offset occurrence temperature as much as possible. As a result, it is possible to expand the fixing temperature region and to impart low-temperature fixability. Therefore, the toner is always required to have a low temperature fixability and an offset resistance.

  More recently, full-color copiers have attracted attention, and there has been a need for satisfying full-color specific requirements from the standpoint of fixing properties. An image forming method for full-color copying is based on a three-color composition method such as a subtractive coloring method. Specifically, first, at least three types of electrostatic latent images are formed on the photosensitive member by exposure, and then the toner is developed and transferred multiple times for each color, and at least three types of electrostatic latent images are formed on the same transfer material such as paper. A toner layer is formed. Next, the superposed images are fixed at once using a heat roller or the like. In this case, compared with black and white development in which the development and transfer processes are performed once, in color development, the thickness of the fixed image is increased by the overlapping of several types of toner layers, and an offset is generated during the fixing. Cheap. Also, in the case of a color image, the image area on the transfer medium increases, so if the film strength of the fixed image is low, the image may be cracked, the gloss may be lost, or image loss may occur when folded. There is. Therefore, the color toner to be fixed needs cohesive force at the time of heat melting, excellent film strength, and appropriate gloss.

Polyester resins are effective from the viewpoint of film strength, and various techniques for using them in combination with crystalline resins have been devised for improving the low-temperature fixability. However, in the kneading and pulverization method, it is difficult to use a crystalline resin that is effective for low-temperature fixability and offset resistance, and sufficient performance can be obtained even if a resin having a high molecular weight or a crosslinked structure is used. There are problems such as not. Furthermore, since the pulverization is performed, it is difficult to control the shape of the toner particles. In particular, it is difficult to make the toner particles spherical, and it is difficult to reduce the toner particle size for the purpose of improving the image quality.
As a toner manufacturing method for solving the above-mentioned problem, there is a wet manufacturing method in which toner particles are prepared by polymerization such as suspension polymerization (see, for example, Patent Document 3). When a wet manufacturing method such as a suspension polymerization method is used, toner particles that are difficult to knead and pulverize can be easily manufactured, and the shape of the toner particles can be controlled, and spherical toner particles can be easily prepared. it can. In addition, the particle size distribution of the toner particles can be controlled. Therefore, there is no need to provide a classification step which is essential for the purpose of homogenizing the toner particles obtained by the kneading and pulverizing method described above.

  On the other hand, the demand for higher image quality such as obtaining halftone gradation and graininess of digital images has been reduced, and it is known that the preferred toner particle size is 9 μm or less. Yes. However, the smaller the particle size of the toner, the larger the van der Waals force, the toner aggregates, the classification efficiency deteriorates in the toner production process by the kneading and pulverization method, and in the wet production method such as the emulsion aggregation method, There is a concern that the drying process becomes complicated, and as a result, there is a problem that the production efficiency is lowered and the manufacturing cost is increased.

  Therefore, in order to ensure powder flowability, methods for adding inorganic or organic fine particles to the toner have been proposed. However, although these methods are effective initially, if copying is repeated over a long period of time, the fine particles on the toner surface are gradually embedded in the toner due to the stirring stress of the developing machine, and the density of the image accompanying the decrease in the charge amount There is a concern that the developability deteriorates due to the decrease or developer fluidity deterioration. In addition, when developing and transferring a plurality of times like a color image, the surface of the photoconductor is exposed to a deteriorated toner surface release agent or a free external additive. In some cases, toner components and external additives adhere to the surface of the photosensitive member, causing image defects, shortening the life of the photosensitive member, and deteriorating toner transferability.

Therefore, for the purpose of improving the above-mentioned photoreceptor contamination, it is a common practice to include an abrasive in the developer. As for the abrasive, various improvement proposals have been conventionally made, such as materials to be used, combinations of specific abrasives, and combinations with other components.
For example, an attempt has been made to add both a friction reducing substance and an abrasive to the toner (see, for example, Patent Document 4). This method can effectively avoid the toner fixing phenomenon to the electrostatic latent image carrier. However, if a friction reducing substance is added to the extent that the toner fixing phenomenon can be avoided, the electrostatic latent image can be repeatedly used. It is difficult to remove low electrical resistance substances such as paper dust and ozone adducts that are generated or adhered to the surface of the carrier, and the latent image on the photoconductor is affected by low electrical resistance, especially in high temperature and high humidity environments. There is a disadvantage that it is significantly damaged. In addition, the addition amount of the friction reducing material and the abrasive is subtle, and adding a sufficient amount of abrasive material so that the deposits on the photoreceptor can be removed stably may damage the photoreceptor. A phenomenon occurs in which the cleaning blade is damaged, resulting in poor cleaning. As abrasives, colloidal silica, surface-modified lipophilic silica, aluminum silicate, surface-treated aluminum silicate, titanium dioxide, alumina, calcium carbonate, antimony trioxide, barium titanate, calcium titanate, strontium titanate, Calcium silicate, magnesium oxide, zinc oxide, zirconium oxide and the like (see, for example, Patent Document 5) are also cerium oxide, aluminum oxide, silicon oxide, zinc oxide, chromium oxide, aluminum sulfate, calcium sulfate, barium sulfate, magnesium sulfate. , Calcium carbonate and the like (for example, see Patent Document 6). Further, a method of forming an image using a developer containing an inorganic fine powder having a BET specific surface area of 0.2 to 30 m ² / g by a nitrogen adsorption method generated by a sintering method (see, for example, Patent Document 7) However, a method for forming an image using a developer containing an oxide ceramic fine powder and a non-oxide ceramic fine powder is disclosed (for example, see Patent Document 8). However, in these conventionally proposed methods, for example, when a photosensitive member such as amorphous silicon is used as the electrostatic latent image carrier, a sufficient cleaning effect cannot be obtained, or the toner is fixed to the photosensitive member. In order to avoid this problem and obtain a sufficient cleaning effect, it is necessary to include a large amount of inorganic fine powder in the developer, or the photoreceptor may be damaged in repeated use. It was.

Further, in recent years, copying machines and developers have been actively exported with the advancement of copying machine technology overseas. Most of the exports are made by inexpensive shipping services. However, depending on the destination of shipping, depending on the export destination, the toner is aggregated in the copier or cartridge during transportation because it crosses the equator or is transported under conditions of high temperature and humidity on the bottom of the ship for several tens of days. There is also a problem that the copy image does not appear in the copy test at the export destination.
Accordingly, from the viewpoint of storage stability of the toner, a material design that can withstand such severe stress as described above is required.
US Patent No. 2,297,691 U.S. Pat. No. 2,357,809 Japanese Patent Publication No.58-49863 JP-A-48-47345 Japanese Patent Laid-Open No. 50-120631 JP 55-57874 A JP-A-60-136752 JP 61-112153 A

  Accordingly, the present invention has been made in view of the above-described circumstances, and its object is to effectively prevent photoconductor contamination and scratches on the photoconductor surface, and to prevent image quality defects for a long time. It is an object of the present invention to provide an electrostatic charge image developing toner excellent in fixing ability and blocking resistance, an electrostatic charge image developer using the toner, and an image forming method using the developer.

As a result of intensive studies to search for a toner having excellent fixability, image quality characteristics, and anti-blocking properties, the present inventors have achieved the above object by using a toner having a silica thin film layer on the particle surface. The present invention was completed by finding out what can be done.
That is, the present invention
<1> An electrostatic charge image developing toner comprising, on the toner base particle surface, porous silicon nitride fine powder having a volume average diameter of 50 to 200 nm and a BET specific surface area of 40 to 120 m ² / g as an external additive. It is.

  <2> The electrostatic charge image developing toner according to <1>, wherein the porous silicon nitride fine powder has an average pore diameter of 0.5 to 20 nm.

  <3> The toner for developing an electrostatic charge image according to <1> or <2>, wherein the toner base particles contain crystalline polyester as a binder resin.

  <4> A release agent is contained in the toner base particles, the melting point of the release agent is in the range of 50 to 110 ° C., and the content of the release agent is the total amount in the toner base particles. The toner for developing an electrostatic charge image according to any one of <1> to <3>, wherein the toner is in a range of 2 to 30 parts by mass with respect to 100 parts by mass of the binder resin component.

  <5> The electrostatic image developing toner according to any one of <1> to <4>, wherein the porous silicon nitride fine powder is treated with an organosilane.

  <6> An electrostatic image developer comprising the electrostatic image developing toner according to any one of <1> to <5>.

  <7> A latent image forming step for forming an electrostatic latent image on the surface of the latent image holding member, and a toner image is formed by developing the electrostatic latent image formed on the surface of the latent image holding member with a developer containing toner. An image development process, a transfer process for transferring the toner image formed on the surface of the latent image carrier to the surface of the transfer target, and a fixing process for fixing the toner image transferred to the surface of the transfer target. A method for forming an image, wherein the developer for electrostatic image according to <6> is used as the developer.

  According to the present invention, it is possible to effectively prevent photoconductor contamination and the occurrence of scratches on the photoconductor surface, suppress image quality defects due to transfer defects and the like, and as a synergistic effect using porous silicon nitride, carrier contamination The electrostatic charge image developing toner that can maintain excellent developability over a long period of time and that has excellent fixability and blocking resistance, and an electrostatic charge image developer using the toner And an image forming method using the developer.

  Hereinafter, the present invention will be described in the order of an electrostatic charge image developing toner, an electrostatic charge image developer, and an image forming method.

<Toner for electrostatic image development>
The toner for developing an electrostatic charge image of the present invention (hereinafter sometimes abbreviated as “toner”) has a volume average diameter of 50 to 200 nm and a BET specific surface area of 40 to 120 m ² / g as an external additive on the surface of the toner base particles. It contains porous silicon nitride fine powder.

  When the volume average diameter of the porous silicon nitride fine powder is less than 50 nm, the porous silicon nitride fine powder on the toner surface may be embedded in the toner due to mechanical stress in the developing machine like other external additives. The effect of improving the contamination of the photoconductor by being detached cannot be expected. On the other hand, when the volume average diameter exceeds 200 nm, the surface of the photoreceptor is damaged.

Further, when the BET specific surface area is less than 40 m ² / g, the specific gravity becomes high. Therefore, when the toner is cleaned, particularly when the blade is cleaned, the photosensitive member is damaged by the frictional force between the cleaning member and the toner. Occurs. Further, when the BET specific surface area exceeds 120 m ² / g, the specific gravity is too low when being mixed with the toner, and there is a problem that it is not externally added to the toner surface as charged. Therefore, by setting the above-mentioned particle diameter and BET specific surface area, the photoreceptor contamination can be effectively improved.

-Measurement of volume average diameter-
Here, the volume average diameter was measured using a laser diffraction particle size distribution analyzer (LA-700: manufactured by Horiba, Ltd.). As a measurement method, 2 g of a measurement sample is added to 50 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate), and dispersed for 2 minutes with an ultrasonic disperser (1,000 Hz) to prepare a sample. The sample in the state of dispersion is adjusted so as to have a solid content of about 2 g, and ion exchange water is added thereto to make about 40 ml. This is put into the cell until an appropriate concentration is reached, waits for about 2 minutes, and is measured when the concentration in the cell becomes almost stable. The obtained volume average diameter for each channel was accumulated from the smaller volume average diameter, and the volume average diameter was determined to be 50%.

-Measuring method of BET specific surface area-
The BET specific surface area was measured by the following method.
Measuring device: BET specific surface area meter SA3100 (manufactured by Beckman Coulter, Inc.), about 0.1 g of porous silicon nitride fine powder as a measurement sample is precisely weighed, put into a sample tube, degassed, It is set as the BET specific surface area of the sample using the numerical value obtained by the automatic measurement of the method.

Moreover, the porous silicon nitride fine powder in the present invention preferably has an average pore diameter of 0.5 to 20 nm, more preferably 1 to 18 nm, and particularly preferably 2 to 15 nm.
Since the specific gravity of the silicon nitride fine powder is reduced by being 0.5 nm or more, when externally added to the toner, there is an advantage that embedding on the surface of the toner due to stress in the developing machine can be reduced, while at 20 nm or less. There is an advantage that the effect of the external additive can be exhibited independently without the other external additive used together being buried in the pores.

-Measurement method of average pore diameter-
The average pore diameter was measured by the following method.
SEM (scanning electron microscope S4700: manufactured by Hitachi, Ltd.) image of porous silicon nitride fine powder photographed at a magnification of 1,000,000 times is binarized with an image analysis device LUZEX FT (manufactured by Nicole Corp.), and 1000 pore diameters are counted. The average diameter was defined as the average pore diameter of the fine powder.

  In addition, as a control method in which the volume average diameter, the BET specific surface area, and the average pore diameter are within the above ranges, for example, when a polysilazane precursor oligomer solution described later is used as a raw material, The average pore diameter of the resulting porous silicon nitride fine powder can be controlled by controlling the degree of pressure reduction of the flow coater when spraying and spraying. In addition, the volume average diameter of the fine powder can be controlled by controlling the amount of the polysilazane solution to be charged and the inlet diameter, and the BET specific surface area can be controlled.

  The porous silicon nitride fine powder used in the present invention is preferably prepared from a precursor oligomer of polysilazane, and its structural formula is represented by the following formula (1).

(However, R ¹ , R ² and R ³ each independently represents a hydrogen atom, an alkyl group, an alkylsilyl group or an alkoxy group. However, at least one of R ¹ , R ² and R ³ is a hydrogen atom. X and Y each independently represent a terminal group selected from a hydrogen atom, an alkyl group, an alkylsilyl group, and an alkoxy group, or bonded to R ¹ , R ^2, or R ³ to form a partial ring, Alternatively, X and Y are combined to form a ring as a whole, and n is an integer between 7 and 50.)

In the formula (1), the alkyl group represented by R ¹ , R ² , R ³ , and X and Y preferably has 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms. The alkyl group may be linear or branched, and may be substituted with a substituent or unsubstituted.
Preferred examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a t-butyl group. Among these, a methyl group and an ethyl group are more preferable.

As the alkyl group in the alkylsilyl group represented by R ¹ , R ² , R ³ , and X and Y, those having 1 to 6 carbon atoms are preferable, and 1 to 4 is particularly preferable. The alkyl group may be linear or branched, and may be substituted with a substituent or unsubstituted.
Preferred examples of the alkylsilyl group include a methylsilyl group, an ethylsilyl group, a propylsilyl group, an isopropylsilyl group, a butylsilyl group, a t-butylsilyl group, a pentylsilyl group, and a hexylsilyl group. Among these, a methylsilyl group, an ethylsilyl group, etc. The group, t-butylsilyl group, is more preferable.

As an alkyl group in the alkoxy group represented by said R < ¹ >, R < ² >, R < ³ > and X and Y, a C1-C4 thing is preferable and 1-3 are especially preferable. The alkyl group may be linear or branched, and may be substituted with a substituent or unsubstituted.
As a preferable alkoxy group, a methoxy group and an ethoxy group are preferable.

Typical examples of the polysilazane precursor oligomer to be used include, but are not limited to, the following. In the general formula (1), those having hydrogen atoms in R ¹ , R ² and R ³ are perhydropolysilazane, and the production method thereof is described in, for example, JP-A-60-145903, D.I. Seyferth et al. Communication of Am. Cer. Soc. , C-13, January 1983. What is obtained by these methods is a mixture of polymers having various structures, but basically includes a chain portion and a cyclic portion in the molecule and can be represented by the following formula (2).

  An example of the structure of perhydropolysilazane is as follows.

A method for producing a polysilazane having a hydrogen atom in R ¹ and R ² and a methyl group in R ³ in the general formula (1) is described in D.C. See Seyferth et al., Polym. Prepre. Am. Chem. Soc. , DIV. Polym. Chem,. 25, 10 (1984). The polysilazane obtained by this method is a chain polymer having a repeating unit of — (SiH ₂ NCH ₃ ) — and a cyclic polymer, and neither has a crosslinked structure.

A method for producing a polyorgano (hydro) silazane having a hydrogen atom in R ¹ and R ³ and an organic group in R ² in the general formula (1) is described in D.C. See Seyferth et al., Polym. Prepre. Am. Chem. Soc. DIV. Polym. Chem,. 25, 10 (1984) and JP-A-61-89230. The polysilazanes obtained by these methods include those having a cyclic structure having a degree of polymerization of 3 to 5 with-(R ² SiHNH)-as the repeating unit, and (R ³ SiHNH) _X [(R ² SiH) _1.5 N _1-X (0.4 <X <1) Some molecules have a chain structure and a ring simultaneously in the molecule.

In the general formula (1), a polysilazane having a hydrogen atom in R ¹ and an organic group in R ² and R ³ , an organic group in R ¹ and R ² , and a hydrogen atom in R ³ are represented by — (R ¹ R ² SiNR ³ ) It has a cyclic structure mainly having a degree of polymerization of 3 to 5, with-as a repeating unit.

  Next, typical examples of polysilazanes to be used are those other than the general formula (1). Some polyorgano (hydro) silazanes include D.I. Seyferth et al. Communication of Am. Cer. Soc. , C-132, July 1984. Some have a cross-linked structure in the molecule as reported. An example is as follows.

Further, polysilazane R ¹ Si (NH) X having a crosslinked structure obtained by ammonolysis of R ¹ SiX ₃ (X: halogen) as reported in JP-A-49-69717, or R ¹ SiX ₃ , R ¹ Polysilazane having the following structure obtained by co-ammonolysis of R ² SiX ₂ can also be used as a starting material.

A preferable polysilazane to be used has a main skeleton composed of the unit represented by the general formula (1) as described above, but the unit represented by the general formula (1) may be cyclized as apparent from the above. When such cyclization does not occur, the terminal of the main skeleton can be the same group as R ¹ , R ² , R ³ or hydrogen.

  Although only some polymers have been described, almost all polysilazane precursors can be used in the preparation of the porous silicon nitride fine powder of the present invention. Moreover, it is preferable that the number average molecular weight of this polysilazane is an oligomer state of 500-2500. If the number average molecular weight is less than 500, even if a silica thin film is formed on the surface of the toner particles, the thin film itself is brittle, so that sufficient effects can be obtained for toner storage stability, blocking properties, and photoreceptor contamination. There may not be. On the other hand, when the number average molecular weight of the polysilazane exceeds 2500, it is not preferable because the porous silicon nitride fine powder may not be uniformly porous when fired.

  When the polysilazane precursor oligomer prepared as described above is put into a flow coater-type pressure type high-temperature baking machine and the oligomer is sprayed in a spray form under a reduced pressure, a small particle size firing ceramic is obtained. This foaming ceramic is heat-treated at 1100 ° C. and then at 1400 ° C. in a nitrogen atmosphere, whereby the porous silicon nitride fine powder is fired.

  The addition amount of the porous silicon nitride fine powder is preferably 0.2 to 15% by mass, and particularly preferably 0.5 to 10% by mass with respect to the toner base particles.

-Binder resin-
-Binder resin: (crystalline) polyester resin-
The polyester resin including the crystalline polyester resin used in the toner of the present invention and all other polyester resins are synthesized from a polyvalent carboxylic acid component and a polyhydric alcohol component. In the present invention, a commercially available product may be used as the polyester resin, or an appropriately synthesized product may be used.

  Examples of the polyvalent carboxylic acid component include oxalic acid, succinic acid, fumaric acid, glutaric acid, adipic acid, peric acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, Aliphatic dicarboxylic acids such as 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malonic acid , Aromatic dicarboxylic acids such as dibasic acids such as mesaconic acid, and alicyclic carboxylic acids such as cyclohexanedicarboxylic acid, and these anhydrides and lower alkyl esters thereof are also included. .

  Examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, and the like, and anhydrides thereof. And lower alkyl esters. These may be used individually by 1 type and may use 2 or more types together.

  Moreover, as an acid component, it is preferable that the dicarboxylic acid component which has a sulfonic acid group other than the above-mentioned aliphatic dicarboxylic acid and aromatic dicarboxylic acid is contained. The dicarboxylic acid having a sulfonic acid group is effective in that it can favorably disperse a coloring material such as a pigment. Further, when the entire resin is emulsified or suspended in water to form fine particles, if there are sulfonic acid groups, as described later, emulsification or suspension can be performed without using a surfactant.

  Examples of the dicarboxylic acid having a sulfone group include, but are not limited to, 2-sulfoterephthalic acid sodium salt, 5-sulfoisophthalic acid sodium salt, and sulfosuccinic acid sodium salt. Moreover, these lower alkyl esters, acid anhydrides, etc. are also mentioned. The divalent or higher carboxylic acid component having a sulfonic acid group is contained in an amount of 1 to 15 mol%, preferably 2 to 10 mol%, based on all carboxylic acid components constituting the polyester. When the content is low, the stability of the emulsified particles with time deteriorates. On the other hand, when the content exceeds 15 mol%, not only the crystallinity of the polyester resin is deteriorated but also the process of coalescing the particles after aggregation is adversely affected. There is a problem that it becomes difficult to adjust.

  Furthermore, it is more preferable to contain a dicarboxylic acid component having a double bond in addition to the aforementioned aliphatic dicarboxylic acid and aromatic dicarboxylic acid. A dicarboxylic acid having a double bond can be suitably used to prevent hot offset at the time of fixing in that it can be radically cross-linked through the double bond. Examples of such dicarboxylic acids include, but are not limited to, maleic acid, fumaric acid, 3-hexenedioic acid, and 3-octenedioic acid. In addition, these lower esters, acid anhydrides and the like are also included. Among these, fumaric acid, maleic acid and the like are mentioned in terms of cost.

  Examples of polyhydric alcohol components include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentylglycol, glycerin, and other aliphatic diols, cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A. And aromatic diols such as bisphenol A ethylene oxide adduct and bisphenol A propylene oxide adduct. One or more of these polyhydric alcohols can be used. Among these polyhydric alcohols, in the case of an amorphous polyester resin, among these polyhydric alcohols, aromatic diols and alicyclic diols are preferable, and among these, aromatic diols are more preferable.

On the other hand, in the case of crystalline polyester, an aliphatic diol is preferable, and a linear aliphatic diol having 7 to 20 carbon atoms in the main chain portion is more preferable. When the aliphatic diol is branched, the crystallinity of the polyester resin is lowered and the melting point is lowered, so that toner blocking resistance, image storage stability, and low-temperature fixability may be deteriorated. Further, when the number of carbon atoms is less than 7, when the polycondensation with aromatic dicarboxylic acid is performed, the melting point becomes high and fixing at low temperature may be difficult. On the other hand, when the number exceeds 20, it is difficult to obtain practical materials. easy. The carbon number is more preferably 14 or less.

  Specific examples of the aliphatic diol suitably used for the synthesis of the crystalline polyester used in the toner of the present invention include ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,5. -Pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12- Examples include, but are not limited to, dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,14-eicosandecanediol, and the like. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferable in view of availability.

  Examples of the trivalent or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and the like. These may be used individually by 1 type and may use 2 or more types together.

  Of the polyhydric alcohol components suitably used for the synthesis of the crystalline polyester used in the toner of the present invention, the content of the aliphatic diol component is preferably 80 mol% or more, more preferably 90% or more. It is. If the content of the aliphatic diol component is less than 80 mol%, the crystallinity of the polyester resin is lowered and the melting point is lowered, so that toner blocking resistance, image storage stability, and low-temperature fixability may be deteriorated. is there.

  If necessary, monovalent acids such as acetic acid and benzoic acid, and monovalent alcohols such as cyclohexanol and benzyl alcohol can be used for the purpose of adjusting the acid value and the hydroxyl value.

The polyester resin can be produced by subjecting the polyhydric alcohol and polyhydric carboxylic acid to a condensation reaction according to a conventional method. For example, the above polyhydric alcohol and polyvalent carboxylic acid, if necessary, a catalyst, and blended in a reaction vessel equipped with a thermometer, a stirrer, a flow-down condenser, and in the presence of an inert gas (such as nitrogen gas), Heat at 150 to 250 ° C. to continuously remove by-product low-molecular compounds out of the reaction system, stop the reaction when a predetermined acid value is reached, cool, and obtain the desired reactant Can be manufactured.

  Examples of the catalyst used for the synthesis of this polyester resin include esterification catalysts such as organic metals such as dibutyltin dilaurate and dibutyltin oxide, and metal alkoxides such as tetrabutyl titanate. The addition amount of such a catalyst is preferably 0.01 to 1% by mass with respect to the total amount of raw materials.

  The amorphous polymer used in the toner of the present invention has a weight average molecular weight (Mw) of 5,000 to 1,000,000 as measured by a gel permeation chromatography (GPC) method in which tetrahydrofuran (THF) is soluble. More preferably, it is 7000-500000, the number average molecular weight (Mn) is preferably 2000-100000, the molecular weight distribution Mw / Mn is preferably 1.5-100, more preferably 2-60. It is.

  When the weight average molecular weight and the number average molecular weight are smaller than the above ranges, while effective for low-temperature fixability, not only the hot offset resistance is remarkably deteriorated, but also the glass transition point of the toner is lowered. The storage stability such as toner blocking is also adversely affected. On the other hand, if the molecular weight is larger than the above range, the hot offset resistance can be sufficiently provided, but the low-temperature fixability is deteriorated and the oozing of the crystalline polyester phase present in the toner is inhibited, so that the document storage stability is reduced. May be adversely affected. Therefore, it becomes easy to satisfy both the low-temperature fixability, the hot offset resistance, and the document storage stability by satisfying the above conditions.

  In the present invention, the molecular weight of the resin is measured with a THF solvent using a TSO gel GPC / HLC-8120, a Tosoh column / TSKgel SuperHM-M (15 cm), and a monodisperse polystyrene standard sample. The molecular weight was calculated using the prepared molecular weight calibration curve.

  The acid value of the polyester resin (the number of mg of KOH required to neutralize 1 g of resin) is easy to obtain the molecular weight distribution as described above, and is easy to ensure the granulation property of the toner particles by the emulsion dispersion method. From the standpoint of easy maintenance of the environmental stability (chargeability stability when the temperature and humidity are changed) of the obtained toner, it is preferably 1 to 30 mgKOH / g. The acid value of the polyester resin can be adjusted by controlling the carboxyl group at the terminal of the polyester according to the blending ratio of the raw polyhydric carboxylic acid and polyhydric alcohol and the reaction rate. Or what has a carboxyl group in the principal chain of polyester is obtained by using trimellitic anhydride as a polyvalent carboxylic acid component.

  The glass transition temperature of the amorphous polymer and the crystalline polyester resin used in the present invention is preferably 35 to 100 ° C., and is 50 to 80 ° C. from the viewpoint of the balance between storage stability and toner fixing property. More preferably. When the glass transition temperature is less than 35 ° C., the toner tends to be blocked during the storage or in the developing machine (a phenomenon in which toner particles are aggregated into a lump). On the other hand, if the glass transition temperature exceeds 100 ° C., the fixing temperature of the toner becomes high, which is not preferable.

-Colorant-
The colorant used in the toner of the present invention is not particularly limited as long as it is a known colorant, and examples thereof include carbon black such as furnace black, channel black, acetylene black, and thermal black, bengara, bitumen, and titanium oxide. Inorganic pigments, fast yellow, disazo yellow, pyrazolone red, chelate red, brilliant carmine, para brown and other azo pigments, copper phthalocyanine, metal-free phthalocyanine and other phthalocyanine pigments, flavantron yellow, dibromoanthrone orange, perylene red, quinacridone red, Examples thereof include condensed polycyclic pigments such as dioxazine violet.

  Chrome Yellow, Hansa Yellow, Benzidine Yellow, Slen Yellow, Quinoline Yellow, Permanent Orange GTR, Pyrarozone Orange, Vulcan Orange, Watch Young Red, Permanent Red, Dupont Oil Red, Resol Red, Rhodamine B Lake, Lake Red C, Rose Bengal, aniline blue, ultramarine blue, calco oil blue, methylene blue chloride, phthalocyanine blue, phthalocyanine green, malachite green oxalate, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment 57: 1, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Examples thereof include various pigments such as CI Pigment Blue 15: 3, and these can be used alone or in combination of two or more.

  In the electrophotographic toner of the present invention, the content of the colorant is preferably 1 to 30 parts by mass with respect to 100 parts by mass of the binder resin. It is also effective to use a pigment dispersant. By appropriately selecting the type of the colorant, yellow toner, magenta toner, cyan toner, black toner and the like can be obtained.

-Release agent-
The release agent used in the toner of the present invention is not particularly limited as long as it is a known release agent. For example, natural waxes such as carnauba wax, rice wax, and candelilla wax, low molecular weight polypropylene, and low molecular weight polyethylene. , Sazol wax, microcrystalline wax, Fischer-Tropsch wax, paraffin wax, montan wax and the like, or mineral / petroleum wax, fatty acid ester, montanic acid ester, etc. It is not a thing. Moreover, these mold release agents may be used individually by 1 type, and may be used together 2 or more types.

  The melting point of the release agent is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, from the viewpoint of storage stability. Moreover, it is preferable that it is 110 degrees C or less from a viewpoint of offset resistance, and it is more preferable that it is 100 degrees C or less.

  The content of the release agent is preferably in the range of 2 to 30 parts by mass, and more preferably in the range of 3 to 20 parts by mass with respect to 100 parts by mass of the binder resin. If the content of the release agent is less than 2 parts by mass, the effect of adding the release agent is not obtained, and hot offset at a high temperature may be caused. On the other hand, if it exceeds 30 parts by mass, the chargeability is adversely affected, and the mechanical strength of the toner is reduced. Therefore, the toner is easily destroyed by stress in the developing machine, and may cause carrier contamination.

The volume average particle size of the electrophotographic toner of the present invention is preferably 1 to 20 μm, more preferably 2 to 8 μm, and the number average particle size is preferably 1 to 20 μm and more preferably 2 to 8 μm.
The volume average particle diameter and the number average particle diameter can be measured, for example, by measuring with a Coulter counter [TA-II] type (manufactured by Coulter, Inc.) with an aperture diameter of 50 μm. At this time, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (Isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more.

 The porous silicon nitride fine powder used in the present invention is preferably pretreated with organosilane. The organosilane used for the surface treatment of the porous silicon nitride fine powder is not particularly limited as long as it is a known organosilane used for the hydrophobic treatment of inorganic fine powder such as silica. Disilazane (HMDS), trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dichlorodimethylsilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloro Ethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, organosilyl mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysila Dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinylterolamethyldisiloxane, 1,3-diphenyl, and the like. Among these, hexamethyldisilazane, Dichlorodimethylsilane is particularly preferred.

-Other additives-
In addition to the above-described components, various components such as an internal additive, a charge control agent, inorganic powder (inorganic fine particles), and organic fine particles can be added to the toner of the present invention as necessary. .
Examples of the internal additive include metals such as ferrite, magnetite, reduced iron, cobalt, nickel, and manganese, alloys, and magnetic materials such as compounds containing these metals.

When the magnetic material is used as a magnetic toner, the ferromagnetic material preferably has an average particle size of 2 μm or less, preferably about 0.1 to 0.5 μm. The amount to be contained in the toner is about 20 to 200 parts by mass, particularly preferably 40 to 150 parts by mass with respect to 100 parts by mass of the resin component. Further, it is preferable that the magnetic characteristics when applied with 10K oersted are those having a coercive force (Hc) of 20 to 300 oersted, saturation magnetization (σs) of 50 to 200 emu / g, and residual magnetization (σr) of 2 to 20 emu / g.

Examples of the charge control agent include quaternary ammonium salt compounds, nigrosine compounds, dyes composed of complexes of aluminum, iron, chromium, and triphenylmethane pigments.
The inorganic powder is added mainly for the purpose of adjusting the viscoelasticity of the toner. For example, silica, alumina, titania, calcium carbonate, magnesium carbonate, calcium phosphate, cerium oxide, etc. Examples thereof include all inorganic fine particles used as an external additive on the toner surface.

Examples of inorganic fine particles and organic fine particles that are externally added to the toner surface include the following.
Examples of the inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, cerium chloride, Examples include Bengala, chromium oxide, cerium oxide, antimony trioxide, magnesium oxide, zirconium oxide, silicon carbide, and silicon nitride. Among them, silica fine particles and titanium oxide fine particles are preferable, and hydrophobized fine particles are particularly preferable.

Inorganic fine particles are generally used for the purpose of improving fluidity. The primary particle diameter of the inorganic fine particles is preferably 1 to 200 nm, and the addition amount is preferably 0.01 to 20 parts by mass with respect to 100 parts by mass of the toner.
Organic fine particles are generally used for the purpose of improving cleaning properties and transfer properties. Specifically, for example, fluorine resin powders such as polyvinylidene fluoride and polytetrafluoroethylene, fatty acid metal salts such as zinc stearate and calcium stearate. , Polystyrene, polymethyl methacrylate and the like.

<Method for producing toner for developing electrostatic image>
The method for producing an electrophotographic toner of the present invention is preferably produced by a wet granulation method. Examples of the wet granulation method include known melt suspension methods, emulsion aggregation methods, and dissolution suspension methods. Among these methods, the emulsion aggregation method is preferably used in the present invention.

The method for producing an electrostatic charge image developing toner of the present invention comprises at least a polyester resin, a colorant, a step of dispersing each raw material in an aqueous dispersion, a step of forming aggregated particles from the raw material dispersion, and heating the aggregated particles And at least a step of fusing them to obtain a toner. In addition, a coating step of coating the surface of the aggregated particles with the same or different resin fine particles as the binder resin is included as necessary.
Hereinafter, each step will be described in detail.

-Emulsification process-
In the toner production method of the present invention, since the binder resin and the colorant are mixed as the respective emulsified particles as the raw material dispersion, the emulsification step is a step of preparing the above-mentioned emulsified dispersion of the raw material. Therefore, first, the binder resin needs to be dispersed in advance as resin particles in the raw material dispersion.

  As an average particle diameter of the said resin particle, it is 1 micrometer or less normally, and it is preferable that it is 0.01-1 micrometer. When the average particle size exceeds 1 μm, the particle size distribution of the finally obtained electrostatic image developing toner is broadened or free particles are generated, which tends to deteriorate performance and reliability. On the other hand, when the average particle size is within the above range, there are no disadvantages, and the uneven distribution among the toners is reduced, the dispersion in the toners is improved, and the variation in performance and reliability is advantageous. The average particle diameter can be measured using, for example, a Coulter counter.

  The dispersion medium in the dispersion is preferably an aqueous medium. Examples of the aqueous medium include water such as distilled water and ion exchange water, and alcohols. These may be used individually by 1 type and may use 2 or more types together. In the present invention, it is preferable to add and mix a surfactant in the aqueous medium. Although it does not specifically limit as surfactant, For example, anionic surfactants, such as sulfate ester type, sulfonate type, phosphate ester type, soap type; amine salt type, quaternary ammonium salt type, etc. Nonionic surfactants such as polyethylene glycol-based, alkylphenol ethylene oxide adduct-based, polyhydric alcohol-based, and the like. Among these, anionic surfactants and cationic surfactants are preferable. The nonionic surfactant is preferably used in combination with the anionic surfactant or the cationic surfactant. The said surfactant may be used individually by 1 type, and may use 2 or more types together.

  Specific examples of the anionic surfactant include sodium dodecylbenzenesulfonate, sodium dodecylsulfate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate and the like. Specific examples of the cationic surfactant include alkylbenzene dimethyl ammonium chloride, alkyl trimethyl ammonium chloride, distearyl ammonium chloride and the like. Among these, ionic surfactants such as anionic surfactants and cationic surfactants are preferable.

  When the binder resin particle is a polyester resin as in the present invention, it contains a functional group that can be converted into an anion type by neutralization, has self-water dispersibility, and part or all of the functional group that can be hydrophilic is a base. A stable aqueous dispersion can be formed under the action of an aqueous medium neutralized with. Since functional groups that can become hydrophilic groups by neutralization in polyester resins are acidic groups such as carboxyl groups and sulfone groups, examples of neutralizing agents include sodium hydroxide, potassium hydroxide, lithium hydroxide, and calcium hydroxide. And inorganic bases such as sodium carbonate and ammonia, and organic bases such as diethylamine, triethylamine and isopropylamine.

  Further, when a polyester resin that does not disperse in water, that is, does not have self-water dispersibility, is used as a binder resin, the resin solution and / or an aqueous medium mixed with the resin solution, as described later, 1 μm easily when dispersed with a polymer electrolyte such as a surfactant, polymer acid, polymer base, etc., heated above the melting point, and treated with a homogenizer or pressure discharge type disperser capable of applying a strong shear force The following microparticles can be made. When this ionic surfactant or polymer electrolyte is used, it is appropriate that the concentration in the aqueous medium is about 0.5 to 5 wt%.

As the colorant to be emulsified and dispersed as the raw material dispersion, the colorants described above can be used.
As a method for dispersing the colorant, any method such as a general dispersion method such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, or a dyno mill can be used, and is not limited at all. If necessary, an aqueous dispersion of these colorants can be prepared using a surfactant, or an organic solvent dispersion of these colorants can be prepared using a dispersant. Hereinafter, such a colorant dispersion may be referred to as a “colored particle dispersion”. As the surfactant and the dispersing agent used for dispersion, the same dispersing agents that can be used when dispersing the binder resin can be used.

The addition amount of the colorant is preferably 1 to 20% by mass, more preferably 1 to 10% by mass, and still more preferably 2 to 10% by mass with respect to the total amount of the polymer. 2 to 7% by mass is particularly preferable, and as much as possible is preferable as long as the smoothness of the image surface after fixing is not impaired. When the content of the colorant is increased, the thickness of the image can be reduced when an image having the same density is obtained, which is advantageous in terms of prevention of offset.
These colorants may be added to the mixed solvent at the same time as other fine particle components, or may be divided and added in multiple stages.

As the release agent emulsified and dispersed as the raw material dispersion, the release agent described above can be used.
As with the case of emulsifying and dispersing a polyester resin that does not have self-water dispersibility, the release agent is dispersed together with an ionic surfactant or the like in water, heated above the melting point, and can be applied with a strong shearing force. Using a pressure discharge type disperser, the dispersed fine particle diameter is adjusted to 1 μm or less. As the dispersion medium in the release agent dispersion, the same dispersion medium as that for the binder resin can be used.

  In the present invention, as an apparatus for mixing and dispersing the binder resin, the release agent, and the plasticizer ester compound with an aqueous medium, for example, a homomixer (Special Machine Industries Co., Ltd.) or a slasher (Mitsui Mining Co., Ltd.) Company), Cavitron (Eurotech Co., Ltd.), Microfluidizer (Mizuho Industry Co., Ltd.), Menton Gorin Homizer (Gorin Co., Ltd.), Nanomizer (Nanomizer Co., Ltd.), Static Mixer (Noritake Company), etc. Examples thereof include a disperser.

  The content of the resin particles contained in the binder resin dispersion in the emulsification step and the content of each of the colorant and the release agent in the dispersion of the colorant and the release agent are usually 5 to 50% by mass. The amount is preferably 10 to 40% by mass. When the content is outside the above range, the particle size distribution may be widened and the characteristics may be deteriorated.

In the present invention, other components such as the internal additive, the charge control agent, and the inorganic powder as described above may be dispersed in the binder resin dispersion according to the purpose.
The charge control agent in the present invention is preferably made of a material that is difficult to dissolve in water in terms of controlling ionic strength that affects the stability of the aggregation process and the fusion process and reducing wastewater contamination.

  The volume average particle size of the other components is usually 1 μm or less, preferably 0.01 to 1 μm. When the average diameter exceeds 1 μm, the particle size distribution of the finally obtained electrostatic image developing toner is broadened or free particles are generated, which tends to deteriorate performance and reliability. On the other hand, when the average particle diameter is within the above range, there are no disadvantages, and the uneven distribution among the toners is reduced, the dispersion in the toner is good, and the variation in performance and reliability is advantageous.

-Aggregation process-
In the agglomeration step, the resin particles obtained in the emulsification step and a dispersion such as a colorant and a release agent are mixed (hereinafter, this mixture is referred to as “raw material dispersion”), and the release agent or the plasticizer. Aggregated particles are formed by aggregating the respective dispersed particles by heating to a temperature not higher than the melting point.

  Agglomerated particles can be formed by acidifying the pH of the raw material dispersion and then adding the flocculant at room temperature under high-speed stirring with a rotary shearing homogenizer to make the flocculant uniform in the raw material dispersion thickened by initial aggregation. This is done by dispersing. The pH is preferably 2 to 6 and more preferably 3 to 6 when the binder resin uses a vinyl copolymer.

  On the other hand, when a polyester resin having a self-water dispersibility containing a functional group that can be anionic by neutralization is used as the binder resin, the pH of the emulsified dispersion of the polyester resin before adjusting the raw material dispersion is 7 to Therefore, when the colorant having a pH of 3 to 5 and the release agent dispersion are mixed or adjusted to the above ph for aggregation, the balance of polarity is lost and slow aggregation occurs. Therefore, when the pH of the polyester resin dispersion is on the alkali side, after adding a surfactant in advance at room temperature to blend the surfactant into the surface of the resin fine particles, after mixing the colorant and release agent , Ph adjustment is preferably performed.

  As the aggregating agent used in the aggregating step, a surfactant having a polarity opposite to that of the surfactant used for the dispersing agent, an inorganic metal salt, or a divalent or higher-valent metal complex can be preferably used. In particular, the use of a metal complex is particularly preferable because the amount of the surfactant used can be reduced and the charging characteristics are improved.

  Examples of the inorganic metal salt include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, and polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. Examples thereof include inorganic metal salt polymers. Of these, aluminum salts and polymers thereof are particularly preferred. In order to obtain a sharper particle size distribution, the valence of the inorganic metal salt is bivalent than monovalent, trivalent than bivalent, trivalent than trivalent, and tetravalent than trivalent. The inorganic metal salt polymer is more suitable.

  In the aggregation step, in order to suppress rapid aggregation due to heating, the pH may be adjusted while stirring and mixing at room temperature, and a dispersion stabilizer may be added as necessary.

In the final toner, it is preferable to add a coating step to the latter half of the aggregation step for the purpose of further improving the chargeability and powder flowability. In this coating step, a coating layer is formed by adhering resin fine particles that are the same as or different from the binder resin to the surface of the above-mentioned aggregated particles, and the formation thereof is a dispersion liquid in which aggregated particles are formed in the aggregation process. It can be carried out by additionally adding a dispersion liquid containing a binder resin or other resin fine particles, and other components may be additionally added as necessary. Also in the coating step, the pH and surfactant are selected according to the resin to be used in the same manner as in the aggregation step, and the coated aggregated particles are obtained while taking care not to unevenly adhere to the surface of the aggregated particles. This coating step is also effective in leading the raw material fine particles that have not been taken into the aggregated particles in the aggregation step.

-Fusion process-
In the fusion step, after the agglomeration is stopped by adjusting the pH of the suspension of aggregated particles (or coated aggregated particles) to a range of 7.5 to 9.5 under the same stirring as in the aggregation step. Then, the aggregated particles (or coated aggregated particles) are fused by heating at a temperature equal to or higher than the melting point of the binder resin. Although depending on the liquidity of the dispersion containing the aggregated particles, if the pH at which aggregation is stopped is not appropriate, the aggregated particles may be dispersed during the temperature rising process for fusing, and the yield may deteriorate. However, the aggregation cannot be stopped, and the particle size growth further proceeds, so that the particle size may become large.

  There is no problem if the heating temperature at the time of fusion is not lower than the melting point of the binder resin contained in the aggregated particles. The heating time may be performed so that the fusion is sufficiently performed, and may be performed for about 0.5 to 3 hours. If it takes more time, the release agent contained in the aggregated particles is likely to be exposed on the toner surface. Therefore, although it is effective for fixing properties, it is not preferable to heat for a long time because it adversely affects the storage stability of the toner.

  In the fusion step, a crosslinking reaction may be performed when the binder resin is heated to the melting point or higher, or after the fusion is completed. In addition, a crosslinking reaction can be performed simultaneously with the fusion. When the crosslinking reaction is performed, for example, an unsaturated sulfonated crystalline polyester resin obtained by copolymerizing a double bond component as a binder resin is used, and a radical reaction is caused to the resin to introduce a crosslinked structure. . At this time, the following polymerization initiator is used.

  Examples of the polymerization initiator include t-butyl peroxy-2-ethylhexanoate, cumyl perpivalate, t-butyl peroxylaurate, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, di-t. -Butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane 1,1-bis (t-butylperoxy) cyclohexane, 1,4-bis (t-butylperoxyca) Bonyl) cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl 4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane, , 3-bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylper) Oxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, di-t-butyldiperoxyisophthalate, 2,2-bis (4,4-di-t-butylperoxy) (Cyclohexyl) propane, di-t-butylperoxy α-methylsuccinate, di-t-butylperoxydimethylglutarate, di-t-butylperoxyhexahydrotereph Tartrate, di-t-butylperoxyazelate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, diethylene glycol-bis (t-butylperoxycarbonate), di-t-butylper Oxytrimethyl adipate, tris (t-butylperoxy) triazine, vinyltris (t-butylperoxy) silane, 2,2'-azobis (2-methylpropionamidine dihydrochloride), 2,2'-azobis [N- (2-carboxyethyl) -2-methylpropionamidine], 4,4′-azobis (4-cyanovaleric acid) and the like.

These polymerization initiators can be used alone or in combination of two or more. The amount and type of the polymerization initiator are selected depending on the amount of unsaturated sites in the polymer and the type and amount of the coexisting colorant.
The polymerization initiator may be mixed with the polymer in advance before the emulsification step, or may be incorporated into the aggregate in the aggregation step. Further, it may be introduced after the fusion step or after the fusion step. When the polymerization initiator is introduced after the aggregation step, the coating step, the fusion step, or the fusion step, a solution in which the polymerization initiator is dissolved or emulsified is added to the particle dispersion (resin particle dispersion or the like). These polymerization initiators may be added with known crosslinking agents, chain transfer agents, polymerization inhibitors and the like for the purpose of controlling the degree of polymerization.

  The fused particles obtained by fusing can be made into toner particles through a solid-liquid separation process such as filtration and, if necessary, a washing process and a drying process. In this case, in order to ensure sufficient charging characteristics and reliability as a toner, it is preferable to sufficiently wash in the washing step.

  In the drying process, an arbitrary method such as a normal vibration type fluidized drying method, a spray drying method, a freeze drying method, or a flash jet method can be adopted. It is desirable that the toner particles have a moisture content after drying of 1.0% or less, preferably 0.5% or less.

  As described above, various known external additives such as inorganic fine particles and organic fine particles as described above can be added to the toner particles granulated through the drying step as described above according to the purpose.

<Developer for developing electrostatic image>
The electrostatic image developing toner of the present invention is used as it is as a one-component developer or as a two-component developer. When used as a two-component developer, it is used by mixing with a carrier.
There is no restriction | limiting in particular as a carrier which can be used for a two-component developer, A well-known carrier can be used. Examples thereof include magnetic metals such as iron oxide, nickel and cobalt, magnetic oxides such as ferrite and magnetite, resin-coated carriers having a resin coating layer on the surface of the core material, and magnetic dispersion carriers. Further, a resin-dispersed carrier in which a conductive material or the like is dispersed in a matrix resin may be used.

  Coating resins and matrix resins used for carriers include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic. Examples thereof include, but are not limited to, acid copolymers, straight silicone resins composed of organosiloxane bonds or modified products thereof, fluororesins, polyesters, polycarbonates, phenol resins, epoxy resins and the like.

  Examples of the conductive material include metals such as gold, silver and copper, carbon black, titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, and carbon black. It is not limited.

Examples of the core material of the carrier include magnetic metals such as iron, nickel, and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. However, in order to use the carrier for the magnetic brush method, it is a magnetic material. It is preferable.
The volume average diameter of the core material of the carrier is generally 10 to 500 μm, preferably 30 to 100 μm.

  In order to coat the surface of the core material of the carrier with a resin, there may be mentioned a method of coating with a coating layer forming solution in which the coating resin and, if necessary, various additives are dissolved in an appropriate solvent. The solvent is not particularly limited and may be appropriately selected in consideration of the coating resin to be used, coating suitability, and the like.

  Specific resin coating methods include an immersion method in which the carrier core material is immersed in the coating layer forming solution, a spray method in which the coating layer forming solution is sprayed onto the surface of the carrier core material, and the carrier core material is fluidized air. And a kneader coater method in which the carrier core material and the coating layer forming solution are mixed in a kneader coater and the solvent is removed in a kneader coater.

  The mixing ratio (weight ratio) of the toner of the present invention and the carrier in the two-component developer is in the range of toner: carrier = 1: 100 to 30: 100, and about 3: 100 to 20: 100. A range is more preferred.

On the other hand, when using the toner for developing an electrostatic charge image of the present invention as a one-component developer and using a magnetic toner containing a magnetic material in the toner, a magnetic toner incorporated in the developing sleeve is used. There is a method of transporting and charging. When non-magnetic toner containing no magnetic material is used, there is a method in which a blade and a fur brush are used to forcibly frictionally charge with a developing sleeve, and the toner is adhered to the sleeve and conveyed.

<Image forming method>
The image forming method of the present invention includes a latent image forming step of forming an electrostatic latent image on the surface of the latent image holding member, and developing the electrostatic latent image formed on the surface of the latent image holding member with a developer containing toner. A developing step for forming a toner image, a transfer step for transferring the toner image formed on the surface of the latent image holding member to the surface of the transfer target, and a fixing for thermally fixing the toner image transferred to the surface of the transfer target. And an electrostatic charge image developing toner of the present invention as the toner.

  The developer may be either a one-component system or a two-component system. As each of the above steps, a known step in the image forming method can be used. The image forming method of the present invention may include steps other than the steps described above.

As the latent image holding member, for example, an electrophotographic photosensitive member and a dielectric recording member can be used.
In the case of electrophotographic photoreceptors, organic photoreceptors are currently the mainstream, but amorphous silicone photoreceptors are particularly preferred from the viewpoint of improving photoreceptor contamination. Since the amorphous silicone photoreceptor has a harder surface than the organic photoreceptor, combining with the porous silicon nitride fine powder of the present invention is more preferable from the viewpoint of preventing photoreceptor contamination.

In the case of an electrophotographic photosensitive member, the surface of the electrophotographic photosensitive member is uniformly charged by a corotron charger, a contact charger or the like and then exposed to form an electrostatic latent image (latent image forming step). Next, the toner particles are attached to the electrostatic latent image by contacting or approaching a developing roll having a developer layer formed on the surface, thereby forming a toner image on the electrophotographic photosensitive member (developing step). The formed toner image is transferred onto the surface of a transfer medium such as paper using a corotron charger or the like (transfer process). Further, the toner image transferred to the surface of the transfer target is heat-fixed by a fixing device, and a final toner image is formed.
In the heat fixing by the fixing machine, a release agent is usually supplied to a fixing member in the fixing machine in order to prevent an offset or the like.

The release agent is preferably not used from the viewpoint of eliminating oil adhesion to the transfer target and image after fixing. However, when the supply amount of the release agent is 0 mg / cm ² , the fixing agent is fixed during fixing. When the member and the transfer medium such as paper come into contact with each other, the amount of wear of the fixing member may increase and the durability of the fixing member may decrease. It is preferable that the amount used is supplied to the fixing member in a small amount within a range of 8.0 × 10 ⁻³ mg / cm ² or less.

When the supply amount of the release agent exceeds 8.0 × 10 ⁻³ mg / cm ² , the image quality deteriorates due to the release agent adhering to the image surface after fixing, and in particular, transmitted light such as OHP is transmitted. When used, such a phenomenon may be prominent. Further, the adhesion of the release agent to the transfer target becomes remarkable, and stickiness may occur. Furthermore, the larger the supply amount of the release agent, the larger the capacity of the tank for storing the release agent, which causes an increase in the size of the fixing device itself.

  Although there is no restriction | limiting in particular as said mold release agent, For example, liquid mold release agents, such as modified oils, such as dimethyl silicone oil, fluorine oil, fluoro silicone oil, and amino modified silicone oil, are mentioned. Among these, modified oils such as amino-modified silicone oil are preferable because they are adsorbed on the surface of the fixing member and can form a homogeneous release agent layer, because they have excellent wettability to the fixing member. Further, from the viewpoint of forming a homogeneous release agent layer, fluorine oil and fluorosilicone oil are preferable.

  Fluorine oil or fluorosilicone oil is used as the release agent because the toner for electrophotography of the present invention is not used, and the conventional image forming method cannot reduce the supply amount of the release agent itself. Although not practical in terms of cost, when the electrophotographic toner of the present invention is used, since the supply amount of the release agent can be drastically reduced, there is no practical problem in terms of cost.

  The method for supplying the release agent to the surface of the roller or belt, which is a fixing member used for the thermocompression bonding, is not particularly limited. For example, a pad method using a pad impregnated with a liquid release agent, a web method, Examples thereof include a roller method and a non-contact type shower method (spray method). Among these, a web method and a roller method are preferable. These methods are advantageous in that the release agent can be supplied uniformly and it is easy to control the supply amount. In order to supply the release agent uniformly to the entire fixing member by the shower method, it is necessary to use a separate blade or the like.

The supply amount of the release agent can be measured as follows. That is, when a normal paper (typically a copy paper manufactured by Fuji Xerox Co., Ltd., trade name J paper) used in a general copying machine is passed through a fixing member supplied with a release agent on its surface. The release agent adheres to the plain paper. The attached release agent is extracted using a Soxhlet extractor. Here, hexane is used as the solvent.
By quantifying the amount of the release agent contained in the hexane with an atomic absorption analyzer, the amount of the release agent adhering to the plain paper can be quantified. This amount is defined as the amount of release agent supplied to the fixing member.

Examples of the transfer target (recording material) to which the toner image is transferred include plain paper, OHP sheet, and the like used in electrophotographic copying machines and printers.
In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the transfer object is as smooth as possible. For example, coated paper in which the surface of plain paper is coated with a resin or the like, art paper for printing Etc. can be used suitably.

  Since the image forming method of the present invention uses the developer of the present invention (the toner of the present invention), low-temperature fixing is possible and the toner can maintain an appropriate triboelectric charge amount. Therefore, it is excellent in energy saving at the time of image formation, and a good image can be formed while preventing the occurrence of toner scattering and the like.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. In the examples, “parts” and “%” are based on mass unless otherwise specified.
-Synthesis of fine silicon nitride powder (1)-
The inside of the 500 ml four-necked flask equipped with a stirring blade, gas inlet tube, dewar condenser, and dropping funnel was depressurized, and the air in the container was depressurized, replaced with nitrogen gas to make an inert atmosphere, and then deaerated. 240 ml of dry pyridine was added and this was ice-cooled. Then, 26 g of dichlorosilane was added under an inert atmosphere to obtain a white solid reaction mixture. The reaction mixture was ice-cooled, and 25.5 g of purified ammonia gas was blown in through a sodium hydroxide tube and an activated carbon tube with stirring for 30 minutes, followed by heating at 100 ° C.

After completion of the reaction, the product was centrifuged, washed with dry pyridine, and then filtered under a dry nitrogen atmosphere to recover 420 ml of filtrate. When the solvent was further removed from the filtrate under reduced pressure, 8.5 g of resinous perhydropolysilazane was obtained. This was 997 when the number average molecular weight was measured by a freezing point depression method (solvent: benzene). Next, after diluting the perhydropolysilazane with xylene, 8 g of a 0.5% xylene solution of palladium (II) propionate was added to 20 g of this polysilazane-xylene solution, and 6 g of xylene was further added, followed by stirring at 20 ° C. in the atmosphere for 3 hours. The reaction was carried out. The solution was further concentrated to prepare a 20% concentration solution.

This polysilazane solution is put into a pressure type flow coater while reducing the pressure, and sprayed so as to normally spray coat the particle surface. The polysilazane firing ceramic precursor is then dispersed in the flow coater. This foaming ceramic precursor was fired at 1100 ° C. in a nitrogen atmosphere for 2 hours, and then at 1400 ° C. for 3 hours, whereby porous silicon nitride fine particles having a particle size of 80 nm, a BET specific surface area of 60 m ² / g, and an average pore size of 5 nm were obtained. A powder was prepared.

-Synthesis of fine silicon nitride powder (2)-
50 g of porous silicon nitride fine powder obtained by synthesis of silicon nitride fine powder (1) is put in a flow coater, dimethyldichlorosilane as a surface treatment agent is sprayed dry, washed with water, and post-cured at 300 ° C. Thus, a silicon nitride fine powder (2) treated with silane was obtained.

-Synthesis of fine silicon nitride powder (3)-
Single silicon was pulverized and heated and nitrided at 1000 to 1500 ° C. in NH ₃ , and the obtained silicon nitride was pulverized to an average particle size of about 500 to 700 nm to obtain silicon nitride powder. The silicon nitride powder thus obtained is poured into water, wet-treated with the silicon nitride powder, and then heated at 1000 ° C. in the presence of oxygen to obtain a silicon nitride powder having an oxide film on the surface. It was. Since part of silicon nitride is fused by the heat treatment, the silicon nitride powder is crushed again, and a silicon nitride fine powder (3) having an average particle size of 300 nm and a BET specific surface area of 5 m ² / g is obtained. Obtained.

-Synthesis of fine silicon nitride powder (4)-
In the synthesis of silicon nitride fine powder (1), when a polysilazane solution prepared in the course of granulation of silicon nitride using a flow coater, the polysilazane solution is sprayed without depressurizing the flow coater and simultaneously heated at 250 ° C. As a result, a silicon nitride preceramic powder was obtained. This was pulverized and fired at 1000 ° C. to obtain fine silicon nitride powder (4) having an average particle size of 30 nm and a BET specific surface area of 80 m ² / g.

-Synthesis of fine silicon nitride powder (5)-
In the synthesis of the silicon nitride fine powder (1), silicon nitride is used except that the nozzle diameter for spraying the polysilanezan solution to the flow coater is halved compared to the synthesis of the silicon nitride fine powder (1). A foam ceramic precursor is prepared through the same steps as fine powder (1), and further fired under the same conditions. Porous silicon nitride fine particles having a particle size of 25 nm, a BET specific surface area of 130 m ² / g, and an average pore size of 3 nm. A powder (5) was obtained.

<Preparation of polyester resin dispersion (1)>
-Bisphenol A ethylene oxide 2 mol adduct 84.6 parts-Bisphenol A propylene oxide 2 mol adduct 217 parts-Trimellitic acid 21 parts-Fumaric acid 46.4 parts-Terephthalic acid 83 parts-Ti (OBu) ₄ 0. 05 parts After the above raw materials were put into a heat-dried three-necked flask, the air in the container was depressurized by a depressurization operation, and the mixture was further brought into an inert atmosphere with nitrogen gas and refluxed at 180 ° C. for 5 hours with mechanical stirring. . Then, vacuum distillation was performed, the temperature was gradually raised to 230 ° C., and the mixture was stirred for 2 hours. When it became viscous, the molecular weight was confirmed by GPC, and when the weight average molecular weight reached 14200, the vacuum distillation was stopped. Polyester resin (1) was obtained.

Subsequently, this was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. Separately prepared aqueous medium tank is filled with 0.35% diluted aqueous ammonia diluted with ion-exchanged water, and heated at 120 ° C. with a heat exchanger at a rate of 0.1 liter per minute, Simultaneously with the polyester resin melt, it was transferred to the Cavitron (Eurotech Co., Ltd.). In this state, the Cavitron was operated under the conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ² to obtain a polyester resin dispersion (resin particle concentration: 20%) made of polyester having an average particle diameter of 0.21 μm. It was.

<Preparation of polyester resin dispersion (2)>
・ Bisphenol A ethylene oxide 2 mol adduct 70.5 parts ・ Bisphenol A propylene oxide 2 mol adduct 232.5 parts ・ Dodecenyl succinic acid 40.8 parts ・ Terephthalic acid 83 parts ・ Isophthalic acid 58.1 parts ・ Ti (OBu) ₄ 0.06 parts After the above raw materials are placed in a heat-dried three-necked flask, the air in the container is depressurized by a depressurization operation, and is then brought to an inert atmosphere with nitrogen gas and refluxed at 180 ° C. for 5 hours with mechanical stirring Went. Then, vacuum distillation was performed, the temperature was gradually raised to 230 ° C and stirred for 2 hours. When the mixture became viscous, the molecular weight was confirmed by GPC, and when the weight average molecular weight reached 16700, the vacuum distillation was stopped. Polyester resin (2) was obtained.

Subsequently, this was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. Separately prepared aqueous medium tank is filled with 0.37% dilute aqueous ammonia diluted with reagent-exchanged ammonia water with ion-exchanged water, heated at 120 ° C. with a heat exchanger at a rate of 0.1 liter per minute, Simultaneously with the polyester resin melt, it was transferred to the Cavitron (Eurotech Co., Ltd.). In this state, the Cavitron was operated under the conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ² , and a polyester resin dispersion (2) made of polyester having an average particle size of 0.25 μm (resin particle concentration: 20% )

<Preparation of release agent dispersion (1)>
・ Ester wax WEP5 (Nippon Yushi Co., Ltd.): 500 parts ・ Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK): 50 parts ・ Ion-exchanged water: 2000 parts Then, after dispersing using a homogenizer (manufactured by IKA: Ultra Tarrax T50), dispersion processing is performed using a Manton Gorin high-pressure homogenizer (Gorin) to disperse a release agent having an average particle size of 0.24 μm. A release agent dispersion (1) (release agent concentration: 20%) was prepared.

<Preparation of release agent dispersion (2)>
・ Carnauba wax (made by Showa Chemical Co., Ltd.): 500 parts ・ Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK): 50 parts ・ Ion-exchanged water: 2000 parts , Dispersed using a homogenizer (manufactured by IKA: Ultra Tarrax T50), and then dispersed with a Manton Gorin high-pressure homogenizer (Gorin) to disperse a release agent having an average particle size of 0.27 nm. A release agent dispersion (2) (release agent concentration: 20%) was prepared.

<Preparation of Colorant Dispersion (1)>
-Cyan pigment (manufactured by Dainichi Seika Co., Ltd., Pigment Blue 15: 3 (copper phthalocyanine)): 100 parts-Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen R): 15 parts-Ion-exchanged water: 900 Part A colorant dispersion obtained by mixing and dissolving the above components and dispersing the colorant (cyan pigment) by dispersing for about 1 hour using a high-pressure impact disperser Ultimateizer (manufactured by Sugino Machine Co., Ltd., HJP30006). Was prepared. The average particle diameter of the colorant (cyan pigment) in the colorant dispersion was 0.14 μm, and the colorant particle concentration was 25%.

<Preparation of crystalline polyester resin dispersion>
To a heat-dried three-necked flask, an acid component of 98 mol% dimethyl sebacate and 2 mol% dimethyl-5-sulfonate sodium, 1,6 hexanediol (2 mol times the acid component), and Ti (as a catalyst) OBu) ₄ (0.014% with respect to the acid component), and then the pressure in the container is reduced by a pressure reducing operation, and the atmosphere is then inerted with nitrogen gas. Reflux for a period of time. Then, excess ethylene glycol was removed by distillation under reduced pressure, the temperature was gradually raised to 230 ° C., and the mixture was stirred for 2 hours. When the mixture became viscous, the molecular weight was confirmed by GPC, and the weight average molecular weight became 13000. The vacuum distillation was stopped and air-cooled to obtain crystalline polyester (1).
Subsequently, this was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. Separately prepared aqueous medium tank is filled with 0.37% dilute aqueous ammonia diluted with reagent-exchanged ammonia water with ion-exchanged water, heated at 120 ° C. with a heat exchanger at a rate of 0.1 liter per minute, Simultaneously with the polyester resin melt, it was transferred to the Cavitron (Eurotech Co., Ltd.). In this state, the Cavitron was operated under the conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ² , and a crystalline polyester resin dispersion (resin particle concentration: 20) made of crystalline polyester having an average particle size of 0.22 μm. %).

-Production of toner base particles (1)-
-Polyester resin dispersion (1): 637.5 parts-Colorant dispersion: 36.0 parts-Anionic surfactant (20% aqueous solution of dofax2A1): 12.75 parts-Release agent dispersion: 67.5 Parts / ion-exchanged water: 496.3 parts Among the above raw materials, a polyester resin dispersion, ion-exchanged water, and an anionic surfactant are placed in a polymerization kettle equipped with a ph meter, a stirring blade, and a thermometer. The surfactant was blended with the polyester dispersion while stirring for a minute. Subsequently, the colorant dispersion (1) and the release agent dispersion (1) were added to and mixed with this, and then a 0.3 M nitric acid aqueous solution was added to the raw material mixture to adjust ph to 3.0. Next, 24 parts of a 10% nitric acid aqueous solution of polyaluminum chloride as a flocculant is dropped while applying a shear force at 1000 rpm with an Ultraturrax. Since the viscosity of the raw material mixture suddenly increases during the dropping of the flocculant, when the viscosity increases, the dropping speed is slowed so that the flocculant is not biased to one place. When the dropping of the flocculant is completed, the number of rotations is further increased to 6000 rpm and the mixture is stirred for 5 minutes to sufficiently mix the flocculant and the raw material mixture.

  Next, the raw material mixture is stirred at 550 to 650 rpm while being heated to 30 ° C. with a mantle heater. After stirring for 30 to 60 minutes, it was confirmed that the primary particle diameter was stably formed using a Coulter counter [TA-II] type (aperture diameter: 50 μm; manufactured by Coulter, Inc.), and then 0.5% for growing aggregated particles. The temperature was raised to 42-50 ° C at a rate of ° C / min. The growth of the agglomerated particles is confirmed at any time using a Coulter counter. The agglomeration temperature and the number of rotations of stirring were appropriately changed depending on the agglomeration speed. When the aggregated particles reached 5.5 μm, in order to stop the growth of the aggregated particles, 1M sodium hydroxide aqueous solution was added to control the pH of the raw material mixture to 9.0.

Subsequently, after adjusting ph to 9.0, when ph begins to decrease naturally, the rotation speed is reduced to 200 rpm or less to prevent the aggregated particles once formed from being dispersed, and then the aggregated particles are fused. Therefore, the temperature is raised to 85 ° C. at 1 ° C./min. During this temperature increase, as the temperature rises, the ph of the raw material mixture decreases, and the aggregated particles that stopped the particle size growth may grow again. Therefore, if necessary, add 1M sodium hydroxide aqueous solution. It is desirable.
After 30 minutes at 85 ° C., the aggregated particles gradually merged, and when about 1 hour had passed, the aggregated particles became spherical and fused. After confirming this fusion state with a microscope, heating was stopped and the temperature was lowered to room temperature at 1 ° C./min.

  The coalesced particles thus obtained are sieved with a 45 μm mesh, washed repeatedly with water, filtered once to separate into solid and liquid, and ion-exchanged water is added to the particles on the filter paper to correspond to a solid content concentration of 20%. The slurry was adjusted. While stirring this slurry, 1M nitric acid was added to maintain ph3.0, acid washing for 30 minutes, and filtration again. The particles on the filter paper were reslurried and repeatedly washed with water, and then dried with a vacuum dryer. The volume average particle diameter of the toner base particles (1) granulated as described above was 5.7 μm.

-Production of toner base particles (2)-
In the production of the toner mother particles (1), granulation is carried out under the same conditions as in the production of the toner mother particles (1) except that no release agent dispersion is used as a raw material. Toner mother particles (2) having an average particle size of 5.4 μm were obtained.

-Production of toner base particles (3)-
Polyester resin dispersion (2): 487.5 parts Crystalline polyester resin dispersion: 150 parts Colorant dispersion: 36.0 parts Anionic surfactant (dowfax2A1 20% aqueous solution): 12.75 parts -Release agent dispersion (2): 67.5 parts-Ion exchange water: 496.3 parts Among the above raw materials, polyester resin dispersion (2) in a polymerization kettle equipped with a ph meter, stirring blades and thermometer. Then, a crystalline polyester resin dispersion, ion-exchange water and an anionic surfactant were added, and the surfactant was blended with the polyester dispersion while stirring at 200 rpm for 15 minutes. Subsequently, the colorant dispersion and the release agent dispersion (2) were added thereto and mixed, and then a 0.3 M nitric acid aqueous solution was added to the raw material mixture to adjust ph to 3.0. Next, 24 parts of a 10% nitric acid aqueous solution of polyaluminum chloride as a flocculant is dropped while applying a shear force at 1000 rpm with an Ultraturrax. Since the viscosity of the raw material mixture suddenly increases during the dropping of the flocculant, when the viscosity increases, the dropping speed is slowed so that the flocculant is not biased to one place. When the dropping of the flocculant is completed, the number of rotations is further increased to 6000 rpm and the mixture is stirred for 5 minutes to sufficiently mix the flocculant and the raw material mixture.

  Next, the raw material mixture is stirred at 550 to 650 rpm while being heated to 30 ° C. with a mantle heater. After stirring for 30 to 60 minutes, it was confirmed that the primary particle diameter was stably formed using a Coulter counter [TA-II] type (aperture diameter: 50 μm; manufactured by Coulter, Inc.), and then 0.5% for growing aggregated particles. The temperature was raised to 42-50 ° C at a rate of ° C / min. The growth of the agglomerated particles is confirmed at any time using a Coulter counter. The agglomeration temperature and the number of rotations of stirring were appropriately changed depending on the agglomeration speed. When the aggregated particles became 5.3 μm, 2.6 parts of anionic surfactant (dowfax2A1 20% aqueous solution) was added and blended for the purpose of coating the aggregated particles, and then the polyester prepared to ph4.0 150 parts of resin dispersion (2) was added dropwise. After the completion of dropping, hold for 5 minutes, and after confirming the adhesion of the resin fine particles to the surface of the aggregated particles with a Coulter counter, in order to stop the growth of the aggregated particles on which the coating layer has been formed, In addition, the pH of the raw material mixture was controlled at 9.0.

  In the subsequent fusing step, in order to fuse the toner together with the coated particles, the temperature is raised to 85 ° C. at 1 ° C./min, held at 85 ° C. for 1 hour, and further held at 95 ° C. for 2 hours to advance the fusion. Was made into a spherical shape and fused. Thereafter, sieving, washing and drying were carried out under the same conditions as for the toner base particles (1) to obtain toner base particles (3) having a volume average diameter of 5.9 μm.

<Examples 1-4 and Comparative Examples 1-6>
To 100 parts of each of the toner base particles (1) to (3), silicon nitride fine powder of the amount shown in Table 1 and titania fine powder and silica fine powder as external additives are added, mixed with a Henschel mixer, and statically mixed. Toners for charge image development (1) to (10) were obtained.

<Evaluation of toner fixing property, document storage property, charging property, storage stability>
(Evaluation of fixability and document preservation)
A two-component developer is prepared by mixing 5 parts of each of the electrostatic charge developing toners (1) to (10) and 100 parts of resin-coated ferrite particles (average particle size 35 μm), which is commercially available for electrophotographic copying. An image was produced using a machine (Fuji Xerox Docucentre color a450) to obtain an unfixed image.

  Next, using a belt nip type external fixing machine, the fixing temperature of the image and the hot offset property were evaluated while gradually increasing the fixing temperature between 100 ° C. and 220 ° C. The low-temperature fixability is determined by fixing an unfixed solid image (25 mm × 40 mm), bending it with a weight under a certain load, grading the degree of image defect at that portion, and fixing temperature at which a certain grade or higher is reached. Was used as an index of low-temperature fixability.

On the other hand, with respect to evaluation of document storability, after fixing two unfixed images created during the fixing evaluation at 160 ° C. with an external fixing machine, the image portion overlaps with the non-image portion and the image portion. Thus, the weight was placed so as to be equivalent to 80 g / cm ^{2 with} respect to the overlapped portion, and left in a constant temperature and humidity chamber at 60 ° C. and 50% humidity for 7 days. After being left, the degree of image loss of the two fixed images superimposed was graded in five stages from “G1” to “G5” shown below.

G1: Since the image portions are adhered to each other, the paper on which the image is fixed is peeled off, image loss is severe, and clear image transfer to the non-image portion is observed.
G2: Since the images are bonded to each other, white spots of image defects are generated in some parts of the image portion.
G3: When separating two superimposed images, image blurring or gloss reduction occurs on the fixing surfaces of each other, but the image has an acceptable level with almost no image loss. Some transition is seen in the non-image area.
G4: When the two overlapped images are separated, a crisp sound is heard, and a slight image shift is observed in the non-image part, but there is no image loss and there is no problem at all. G5: Both the image part and the non-image are completely absent. There is no image loss or image transfer.

(Evaluation of electrification)
Toner for electrostatic charge image development (1) to (10) 1.5 parts each and resin-coated ferrite particles (average particle diameter 35 μm) 30 parts are weighed in a glass bottle with a lid, under high temperature and high humidity (temperature 28). And seasoning for 24 hours under low temperature and low humidity (temperature 10 ° C., humidity 15%), and then shaken with a tumbler mixer for 5 minutes. The charge amount (μc) of the toner in both environments was measured with a blow-off charge amount measuring device.

(Evaluation of storage stability)
Electrostatic charge image developing toners (1) to (10) 100 g each were weighed and left in a chamber at 60 ° C. and 80% humidity for 24 hours. The toner was placed on a 45 μm sieve, and the sieve was vibrated. The amount remaining above was weighed, and the degree of aggregation was evaluated by the percentage of the remaining toner.

<Evaluation of image quality and photoconductor contamination>
A two-component developer was prepared by mixing 8 parts of each of the electrostatic charge developing toners (1) to (10) and 100 parts of resin-coated ferrite particles (average particle size: 35 μm), which was then commercially available for electrophotographic copying. A copy test of 30,000 sheets was performed using a machine (Fuji Xerox Docucentre color a450) to evaluate the image quality of the copied image and at the same time evaluate the contamination of the photoreceptor after 30,000 sheets.
Regarding the contamination of the photoreceptor, the surface of the photoreceptor was visually observed, and the degree of contamination was graded from the following viewpoints.
G1: Many remarkable deposits are observed on the surface of the photoreceptor, and it is confirmed that the entire surface remains in a pattern like a toner streak.
G2: Deposits were observed on the photoreceptor surface in some places.
G3: A level with no problem in image quality although there is a slight amount of deposit on the surface of the photoreceptor.
G4: Although some deposits can be confirmed with a microscope, it is difficult to visually confirm and the contamination is extremely small.

Table 2 shows the fixing characteristics, document storage characteristics, charging characteristics, toner storage stability, image quality, and photoreceptor contamination of the toner shown in Table 1.
From the results shown in Table 2, since Examples 1 to 4 contain porous silicon nitride fine powder, which is a feature of the present invention, as an external additive, both low-temperature fixability and hot offset property are achieved. Excellent characteristics in document storage, chargeability and toner storage. In addition, since porous silicon nitride appropriately scrapes off deposits on the photoconductor, the image quality and photoconductor contamination were excellent without impairing other characteristics. On the other hand, in Comparative Examples 1 to 3, since no silicon nitride was contained, there was no problem in fixability and chargeability, but toner storage, image quality, and photoreceptor contamination were significantly deteriorated. In Comparative Example 4, although porous silicon nitride is used, the particle size is small and the BET specific surface area is large, so that the intended function of the silicon nitride fine powder is not achieved and the toner is embedded in the toner. It caused photoconductor contamination and adversely affected image quality. Further, in Comparative Examples 5 and 6, although silicon nitride is added, it is not a porous structure. In Comparative Example 5, since the particle size is large, although there is an effect of scraping off the adhering matter to the photoreceptor, it is remarkable. In Comparative Example 6, since the particle size is small, the toner particles are buried in the toner surface, and the effect of scraping the expected fixed matter is not exhibited, resulting in deterioration of image quality and occurrence of white spots. I was there.

<Examples 5 and 6>
Similar to the developer used for image quality evaluation in Example 3 and Example 4, electrostatic charge developing toners (3) and (4) are mixed with resin-coated ferrite particles (average particle size of 35 μm) to form two components. A developer was prepared, and an electrophotographic copying machine (Docucentre color a450 manufactured by Fuji Xerox Co., Ltd.) was used to conduct a 50,000-sheet copying test to evaluate photoreceptor wear and scratches.

<Examples 7 and 8>
To 100 parts of each of the toner base particles (3) and (4), 1.2 parts of porous silicon nitride fine powder and 0.5 part of titania fine powder are mixed with a Henschel mixer to obtain an electrostatic charge image developing toner (11 ) And (12) were obtained. A developer is prepared by mixing 1.5 parts of each of the toners for developing electrostatic images (11) and (12) and 30 parts of a ferrite carrier coated with a silicone resin and having an average particle size of 35 μm. In the same manner as described above, a copying test of 50,000 sheets was performed to evaluate photoconductor wear and scratches.

  As a result, in Examples 5 and 6 which are organic photoreceptors, although there was no effect on the image quality, scratches and wear on the photoreceptor were noticeable, but in Examples 7 and 8 using an amorphous silicon photoreceptor, There were no noticeable scratches and little photoreceptor wear.

Claims (3)

A toner for developing an electrostatic charge image, comprising a fine particle of porous silicon nitride having a volume average diameter of 50 to 200 nm and a BET specific surface area of 40 to 120 m ² / g as an external additive on the surface of the toner base particles.   An electrostatic charge image developer comprising the electrostatic charge image developing toner according to claim 1. A latent image forming step for forming an electrostatic latent image on the surface of the latent image holding member, and a developing step for developing the electrostatic latent image formed on the surface of the latent image holding member with a developer containing toner to form a toner image. And a transfer step of transferring the toner image formed on the surface of the latent image carrier to the surface of the transfer target, and a fixing step of fixing the toner image transferred to the surface of the transfer target. There,
An image forming method comprising using the electrostatic charge image developer according to claim 2 as the developer.