JP2004110008A - Electrostatic charge image developing toner and image forming method using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic charge image developing toner which can form good images free from dark dots without causing fogging even after repeated printing, provides the absence of leakage of the electrostatic charge quantity at and under a high temperature and high humidity, the absence of an increase in the electrostatic charge quantity at and under a low temperature and low humidity, the long lifetime of a developer, the absence of contamination outside the machine, a good preservability, the absence of elimination of external additives, and high transferability, and has the high adaptability to a cleanerless process and high-speed machine and an image forming method using the electrostatic charge image developing toner. <P>SOLUTION: The electrostatic charge image developing toner contains metal oxide particles including at least a resin, coloring matter and ≥2 metal elements. The metal oxide particles have a domain matrix structure, in which the particles having the above domains are 5 to 49number% in the metal oxide particles. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an electrostatic latent image developing toner and an image forming method using the electrostatic latent image developing toner.

Conventionally, as an electrophotographic image forming method using an electrostatic image developing toner, a dry developing method using a magnetic brush or the like is generally used from the viewpoint of simplicity. In the technical field of electrophotography, the development competition for color printers that are small in size, capable of high-speed image formation, and have high image quality is intensifying.

As a technology for realizing the miniaturization of color printers, for example, a so-called cleanerless process that enables the removal of the cleaner unit by devising the charging and developing bias while designing the transfer device simply and compactly is known. (For example, see Patent Document 1).

As a typical example of the above-mentioned problem in the apparatus, there is an image forming method using a polymerized toner produced by a polymerization method, and an image is formed using a polymerized toner having a small particle diameter and a sharp particle size distribution and shape distribution. Attention has been paid to the fact that a high-quality toner image having excellent fine line reproducibility can be obtained when formed.

重合 In addition, in the case of the polymerized toner, the charge of the toner particles is uniform, so that high transferability can be obtained, and since the polymerized toner is compatible with a cleanerless process, it is advantageous in achieving miniaturization of the apparatus.

From the viewpoint of cleanerlessness, an increasing number of manufacturers adopt an external additive having a relatively large particle diameter (an external additive having a large particle diameter whose average primary particle diameter is as large as about 300 nm) (for example, Patent Document 3). reference.). The purpose of using an external additive having a large particle size is to stabilize development and to exhibit high transferability.

Therefore, a technique of combining the above-described polymerized toner and a large particle size external additive, each of which is a technique for improving the toner transferability, is disclosed. There is a problem that the adhesion and fixation strength of the large particle size external additive to the particle surface is weak, and the large particle size external additive is easily detached from the toner particle surface (for example, see Patent Document 4).

It is considered that the reason for this is that many of the toner particles produced by the polymerization method have no corners on the particle surface, and thus cannot physically strongly trap the external additive.

問題 Further, problems caused by detachment of the external additive from the toner particles include the following.

(A) For example, in the case of a two-component developer, the detached external additive is transferred to the surface of the developing roller on which the carrier and the frictional charging member are provided, and the external additive is contaminated, so that the triboelectric charge is reduced. It is hindered and poor charging easily occurs. As a result, the life of the developer and the developing device is reduced.

(B) The detached external additive pierces or polishes the surface of the heating roll of the developing device or the surface of the photoreceptor to generate an abnormal point (for example, a scratch). In the area where the abnormality has occurred, black spots or white spots occur in the art because toner offset occurs or the potential does not decrease.

(C) The detached external additive contaminates a charging device (mainly, a charging wire of a charging device), thereby causing a poor charging to occur at a contaminated place. Streaks occur.

(D) The detached external additive contaminates the carrier surface of the developer and fluctuates or increases the charge amount (especially in a low-temperature and low-humidity environment) to cause image fog.

Large particle size silica (for example, refer to Patent Document 3) is effective in increasing the adhesion / fixing strength of the external additive to the toner particles. However, when the large particle size silica particles are used, the chargeability is strong. However, there is a problem that the charge amount of the toner may increase.In addition, large-diameter silica, which has high chargeability, enhances transferability in a low humidity environment, but when combined with a small-diameter photoreceptor, peeling discharge occurs when separated from the transfer material. There is a problem that the halftone tends to be uneven due to discharge (often referred to by those skilled in the art as transfer repelling).

further,
(E) There is also a problem that when the developer is left at a high temperature and a high humidity, a charge amount leaks and an image fog occurs.
JP-A-2002-132015 JP 2000-214629 A JP 2001-66820 A JP 2002-287410 A

The present invention has been made in view of the above problems.

A first object of the present invention is to provide a toner for developing an electrostatic image capable of prolonging the life of a developer by finding toner particles and an external additive in which the external additive does not separate from the surface of the toner particles. (Hereinafter simply referred to as toner) and an image forming method using the toner.

A second object of the present invention is to prevent the occurrence of abnormal points on the surface of the fixing roll or the photoreceptor by preventing the external additive from separating from the surface of the toner particles, and to use a toner that does not generate black spots or white spots. To provide an image forming method.

A third object of the present invention is to prevent the external additive from being detached from the surface of the toner particles, thereby preventing the charging wire of the charger from being contaminated and causing uneven discharge, and a toner which does not generate halftone white streaks. An object of the present invention is to provide an image forming method using the toner.

A fourth object of the present invention is to provide a toner which exhibits little change or increase in chargeability due to the addition of an external additive, exhibits good transferability without causing transfer repellency, and has compatibility with a cleanerless process, and a toner having the same. To provide an image forming method using the same.

A fifth object of the present invention is to use an external additive having a large particle size so that the external additive does not become buried in the toner particles, and the fluidity of the toner can be ensured even when left at a high temperature. An object of the present invention is to provide a toner having excellent storage stability and an image forming method using the toner.

A sixth object of the present invention is to provide a toner which does not cause a charge leakage of the developer even when the developer is left at high temperature and high humidity, and an image forming method using the toner.

The present inventors assumed that the structure of the external additive exerts some action as a factor for exhibiting a stable trapping performance of the external additive on the toner particle surface. The present inventors have found that stable trapping performance is exhibited when metal oxide particles having a domain matrix structure are used as an external additive, thereby achieving the present invention.
(Claim 1)
In a toner for developing an electrostatic image containing at least a resin, a colorant and metal oxide particles containing two or more metal elements, the metal oxide particles have a domain-matrix structure, and the particles having the domains are made of metal. 5 to 49% by number of oxide particles in the toner for developing an electrostatic image.

In the present invention, attention has been paid to the presence of particles having domains in metal oxide particles having a domain matrix structure. When the ratio of the particles having domains to the metal oxide particles is 5 to 49% by number, the metal oxide particles exhibit stable traps with respect to the toner particles, and the metal oxide particles separate from the toner particles. Made it possible not to.
(Claim 2)
The electrostatic image developing toner according to claim 1, wherein the matrix of the metal oxide particles is silica.
(Claim 3)
2. The electrostatic image developing toner according to claim 1, wherein the domain is formed of a titanium compound.
(Claim 4)
2. The electrostatic image developing toner according to claim 1, wherein the domain is made of an aluminum compound.
(Claim 5)
The toner according to claim 1, wherein the domain comprises a zirconium compound.
(Claim 6)
The average primary particle diameter based on the number of the metal oxide particles is in a range of 10 to 300 nm, and the average horizontal Feret diameter based on the number of the domains is in a range of 1 to 60 nm. For developing electrostatic images.
(Claim 7)
The ratio of toner particles having no corners among the toner particles constituting the toner for developing an electrostatic charge image is 50% by number or more, and the number variation coefficient in the number particle size distribution is 27% or less. Item 4. The toner for developing an electrostatic image according to Item 1.
(Claim 8)
2. The electrostatic image developing toner according to claim 1, wherein the electrostatic image developing toner is encapsulated or surface-modified with different resin compositions. 3.
(Claim 9)
Forming a toner image composed of an electrostatic image developing toner on an image forming support, and fixing the toner image on the image forming support by passing the toner image between a heating member and a pressing member; 2. An image forming method according to claim 1, wherein said electrostatic image developing toner is the electrostatic image developing toner according to claim 1.

The metal oxide particles used in the toner according to the present invention are not buried in the toner particles or separated from the surface of the toner particles, so that fog does not occur even if the printing is repeatedly performed, black spots, white spots and halftones. It is possible to form a good image without generating white streaks, and there is no increase in charge amount even at low temperature and low humidity (for example, 10 ° C. and 20% RH), and the developer can be used at high temperature and high humidity (for example, 30 ° C. and 85% RH). There is no charge leakage, the life of the developer is long, the preservability is good, there is no detachment of external additives, the transferability is high, and the suitability for a cleaner-less process is high.

Specifically, since the metal oxide particles are trapped on the surface of the toner particles and do not separate, the metal oxide particles do not scatter and do not adhere to the carrier surface of the developer, so that the life of the developer is long and good.

Further, since the electric resistance of the metal oxide particles used in the present invention does not cause the leakage of the charge amount of the developer at high temperature and high humidity and is suitable for increasing the transfer rate, it is necessary to clean the transfer residual toner. It has high compatibility with cleanerless processes.

In addition, since the metal oxide particles hardly migrate to the carrier surface of the developer, the charge amount of the developer and the toner can be stably maintained even when printing is repeated, and the charge amount does not increase even at a low temperature and a low humidity. Generation is suppressed.

Further, since the metal oxide particles used in the present invention have low abrasiveness, polishing scratches are less likely to occur on the surface of the photoreceptor and the surface of the fixing roll, and the generation of white spots and black spots due to the polishing scratches can be suppressed.

In addition, since the metal oxide particles used in the present invention have a large particle size, the toner using the metal oxide particles as an external additive has good fluidity and generates granules even when stored in a high-temperature and high-humidity environment. Can be prevented.

ト ナ ー The toner according to the present invention contains at least a resin, a colorant, and two or more metal elements, and contains metal oxide particles having a domain matrix structure. The metal oxide particles have a large particle size, are hardly buried in the toner particles, and have a property that they are not detached from the surface of the toner particles because they are firmly trapped on the surface of the toner particles.

As described above, in the present invention, when the metal oxide particles having a domain matrix structure are used as an external additive and the ratio of the particles having the domain in the metal oxide particles is 5 to 49% by number, the surface of the toner particles is reduced. It was confirmed that separation of the metal oxide particles did not occur.

As described above, it is not clear why the metal oxide particles do not detach from the surface of the toner particles by setting the ratio in the metal oxide particles having the domain matrix structure within a specific range. Particles with low resistance and domains with high dielectric properties are contained in matrices with high electrical resistance, so the metal oxide particles themselves have strong trapping properties for toner particles due to the dielectric action of the particles with domains. It is presumed that it came to have.

{Circle around (5)} It is presumed that the metal oxide particles did not detach from the surface of the toner particles due to the strong and stable trapping action.

Hereinafter, the present invention will be described in detail.

《Metal oxide particles》
(Metal oxide particles having a domain matrix structure)
The metal oxide particles having a domain matrix structure according to the present invention will be described with reference to FIG.

FIG. 1 is a cross-sectional view of a metal oxide particle having a domain matrix structure.

に お い て In FIG. 1, 1 indicates metal oxide particles, 2 indicates a matrix (also referred to as the sea) which is a continuous phase region, and 3 indicates a domain (also referred to as an island).

The domain matrix structure is also called a sea-island structure. As shown in FIG. 1, a closed interface (a boundary between phases) is formed in a continuous phase (a continuous phase is a matrix and a region representing the sea). Having an island-like phase having the following structure.

In other words, the metal oxide particles according to the present invention contain, in the metal oxide particles, components that form independent phases (domain (island) and matrix (sea)) without being mutually compatible with each other. One forms an island-like phase and the other forms a sea-like phase to form metal oxide particles having a domain matrix structure (sea-island structure).

(Observation of domain matrix structure)
In the observation of the domain matrix structure of the metal oxide particles according to the present invention, the particles are observed using a field emission transmission electron microscope (FE-TEM), and at the same time, the target element is mapped. It can be done by doing.

(Number of particles having domains in metal oxide particles%)
The number% of particles having domains in the metal oxide particles is 5 to 49% by number, preferably 10 to 40% by number.

個数 Calculation of the number% of the particles having domains in the metal oxide particles is performed by obtaining the element ratio between the metal elements in the domains and the metal elements constituting the matrix by commercially available X-ray fluorescence analysis.

For example, when the domain is titanium oxide (TiO ₂ ) and the matrix is silica (SiO ₂ ), elemental analysis using X-rays is performed by focusing on Ti in the domain and Si in the matrix. each amount of TiO _2, in terms of SiO ₂ amount is calculated using the following equation.

(formula)
(TiO ₂ ) / (TiO ₂ + SiO ₂ ) × 100 (number%)
The metal oxide particles according to the present invention include two or more metal elements, and preferable metal elements include Si, Ti, Mg, Al, Sn, Ge, Zr, Zn, and the like. Examples of the element include Si and Ti.

個数 The number-based average primary particle diameter of the metal oxide particles according to the present invention is preferably 10 to 300 nm, more preferably 35 to 180 nm, and still more preferably 60 to 140 nm.

平均 The average Feret horizontal diameter based on the number of domains is preferably 1 to 60 nm, more preferably 2 to 60 nm, and still more preferably 4 to 20 nm.

フ ェ The horizontal Feret horizontal diameter of the domain and the average primary particle diameter of the metal oxide particles having the domain matrix structure can be determined by a transmission electron microscope. At this time, it can also be determined by using a commercially available image analyzer “Luzex F” (manufactured by Nikol Japan Co., Ltd.).

Here, the Feret horizontal diameter indicates the horizontal length of the particles when the particles are placed on the horizontal in an arbitrary state, and the Feret horizontal diameter of the island part is arbitrarily set in this way. The horizontal length of each island present inside the metal oxide particles.

Next, a method for producing metal oxide particles will be described.

金属 The metal oxide particles according to the present invention can be produced by a flame combustion method or a wet method, but are preferably produced by a flame combustion method.

The basic manufacturing method for forming a domain matrix structure is a method in which a silane coupling agent containing no halogen and a metal coupling agent are mixed in a liquid state and sprayed from a burner into a flame.

The domain diameter can be controlled by the amount of halogen contained in the raw material. When the amount of halogen is increased, the domain becomes finer. The halogen content is preferably from 2 to 14% by mass. The number% of the particles having domains in the metal oxide particles can be changed by the mixing ratio of the silane coupling agent and the metal coupling agent used as a raw material. In order to reduce the number% of the particles having domains, that is, to make the number within the range of the present invention, it is possible to reduce the mixing ratio of the metal coupling agent to less than 50% by mass.

FIG. 2 is a flowchart showing an example of a production apparatus for producing metal oxide particles.

In FIG. 2, a raw material (mixture of a metal coupling agent) 21 is guided from a raw material tank 22 to a main burner 26 having a spray nozzle at the tip thereof through a feed pipe 25 by a constant-rate supply pump 23 and sprayed. The raw material 21 is sprayed into a combustion furnace 27 and ignited by an auxiliary flame to form a combustion flame 28. The metal oxide particles generated by the combustion are cooled together with the exhaust gas in the flue 29, separated by the cyclone 30 and the bag filter 33, and collected in the collectors 31 and 33. The exhaust gas is exhausted by the exhaust fan 34.

《Toner particles》
The resin and the colorant constituting the toner particles according to the present invention will be described in a later-described manufacturing method. Here, preferred features of the toner particles will be described.

(Toner particles without corners)
The toner particles according to the present invention are preferably “tonerless toner particles” as the particle shape from the viewpoint of reducing the cohesiveness of the toner particles.

(4) The ratio of toner particles having no corners in the toner particles is preferably at least 50% by number, more preferably from 60 to 95% by weight, and even more preferably from 65 to 85% by number.

When the ratio of the toner particles having no ５０ angle is 50% by number or more, the gap of the transferred toner layer (powder layer) is reduced, the fixing property is improved, and the offset is hardly generated. In addition, the amount of toner particles that are liable to be worn or broken and the number of toner particles having a portion where charges are concentrated are reduced, the charge amount distribution is sharpened, the chargeability is stabilized, and good image quality can be formed over a long period of time. it can.

Here, the “toner particles having no corners” refer to toner particles having substantially no protrusions on which electric charges are concentrated or protrusions that are easily worn out by stress. Are called toner particles having no corners.

FIG. 3 is a diagram showing an example of toner particles having no corners.

As shown in FIG. 3A, when the major axis of the toner particle T is L, a circle C having a radius (L / 10) is in contact with the peripheral line of the toner particle T at one point and the inside is inward. A case where the circle C does not substantially protrude outside the toner particle T when the roller is rolled is referred to as a “toner particle having no corner”. “Case where the protrusion does not substantially protrude” refers to a case where the protrusion where the protruding circle exists is one or less. Further, the “longer diameter of the toner particle” refers to the width of the particle at which the interval between the parallel lines becomes maximum when the projected image of the toner particle on the plane is sandwiched between two parallel lines. FIGS. 2B and 2C show projected images of toner particles having corners, respectively.

The measurement of the ratio of the toner particles having no angle was performed as follows. First, a photograph in which toner particles are enlarged by a scanning electron microscope is taken, and further enlarged to obtain a photographic image of 15,000 times. Next, the presence or absence of the corners is measured for this photographic image. This measurement was performed for 100 toner particles.

There is no particular limitation on a method for producing toner particles having no angle. Specifically, a method of spraying the toner particles into a hot air flow, a method of repeatedly applying mechanical energy by an impact force in a gas phase, or a method of adding a toner particle to a solvent that does not dissolve the toner particles and rotating Can be produced by a method of imparting

(Number variation coefficient in number flow rate distribution of toner particles)
The toner particles according to the present invention preferably have a number variation coefficient of 27% or less in the number particle size distribution, more preferably 9 to 25%, and still more preferably 12 to 21%. When an image is formed using toner particles having a number variation coefficient of 27% or less in the number particle size distribution, effects such as stable charging characteristics of the toner and less occurrence of cleaning failure are exhibited.

個数 The “number variation coefficient in number particle size distribution”, which is one variable indicating the uniform shape of toner particles, can be measured with “Coulter Counter TA” or “Coulter Multisizer” (manufactured by Coulter Corporation). In the present invention, measurement was performed using a “Coulter Multisizer” with an interface for outputting a particle size distribution (manufactured by Nikkaki Co., Ltd.) and a personal computer connected. The particle size distribution and the number average particle size were calculated by measuring the volume and number of toner particles having a particle size of 1 μm or more using an aperture of 100 μm as the aperture used in the “Coulter Multisizer”. The number particle size distribution represents the relative frequency of the toner particles with respect to the particle size, and the number average particle size represents the median size in the number particle size distribution. The “number variation coefficient in the number particle size distribution” of the toner particles (hereinafter, also referred to as the number variation coefficient of the toner particles) is calculated from the following equation.

Coefficient of variation in number of toner particles = (S2 / Dn) × 100 (%)
In the formula, S2 indicates the standard deviation in the number particle size distribution, and Dn indicates the number average particle size (μm).

個数 The control of the number variation coefficient of the toner particles can be performed by a known method. For example, a method of classifying toner particles by wind force can be used, but classification in a liquid is effective for further reducing the number variation coefficient. As a method of classifying in a liquid, there is a method of separating and collecting toner particles according to a difference in sedimentation speed caused by a difference in toner particle diameter by controlling a rotation speed by using a centrifugal separator.

In particular, in the case of producing toner particles by a suspension polymerization method or the like, a classification operation is indispensable in order to reduce the number variation coefficient in the number particle size distribution to 27% or less. In the suspension polymerization method, it is necessary to disperse the polymerizable monomer into oil droplets of a desired size as toner particles in an aqueous medium before polymerization. That is, mechanical shearing by a homomixer, a homogenizer, or the like is repeated on a large oil droplet of the polymerizable monomer to reduce the oil droplet to a size of about a toner particle. In the method using the shearing method, the number and particle size distribution of the obtained oil droplets becomes wide, and therefore, the particle size distribution of toner particles obtained by polymerizing the oil droplets becomes wide. Therefore, it is preferable to perform a classification operation.

ト ナ ー The toner particles according to the present invention are encapsulated or surface-modified by different resin compositions.

Here, encapsulation and surface modification means measuring the viscoelastic image of the cross section of the toner particle using a commercially available scanning atomic force microscope, and the hardness or viscoelastic behavior of the inside and the surface side of the toner particle are different. Is referred to as encapsulation, and a case where the hardness is partially different or the viscoelastic behavior is different is defined as surface-modified.

As a means for producing the encapsulated toner particles and the surface-modified toner particles, a resin having a higher Tg (glass transition point) on the surface side than the resin inside the toner particles is used to cover the entire surface (encapsulation). ) Or partial coating (surface modification).

方法 The method for producing the toner particles according to the present invention is not particularly limited, and can be produced by a known method.

Hereinafter, resin particles are formed in the absence of a colorant, a dispersion of the colorant particles is added to a dispersion of the resin particles, and the resin particles and the colorant particles are salted out, aggregated, and fused. A method for producing toner particles will be described.

According to the above-described production method, the resin particles are prepared in a system in which no colorant is present, so that the polymerization reaction for obtaining the composite resin particles is not hindered. Therefore, when an image is formed using the toner particles, the toner has excellent offset resistance and does not cause contamination of the fixing device or image stain due to accumulation of toner.

Further, as a result of the polymerization reaction for obtaining the resin particles being reliably performed, no monomer or oligomer remains in the obtained toner particles, and a large number of prints are performed using the toner particles. No odor is generated from the heat fixing device.

Further, the surface characteristics of the obtained toner particles are uniform and the charge amount distribution is sharp, so that an image having excellent sharpness can be formed over a long period of time.

One or more coating layers made of a resin having a different molecular weight and / or composition from the resin forming the core particles are formed so that the resin particles constituting the toner particles cover the surfaces of the core particles made of the resin. Preferred are resin particles having a multilayer structure.

That is, the molecular weight distribution of the resin particles is not monodisperse, and the resin particles usually preferably have a molecular weight gradient from the center (nucleus) to the outer layer (shell).

(4) It is preferable to use the “multi-stage polymerization method” to obtain resin particles from the viewpoint of controlling the molecular weight distribution, that is, from the viewpoint of securing fixing strength and offset resistance. In the present invention, the “multi-stage polymerization method” for obtaining resin particles refers to a method in which a monomer (n) is subjected to polymerization treatment (n-th stage), (N + 1) is subjected to a polymerization treatment (the (n + 1) th step), and a polymer of the monomer (n + 1) (dispersion and / or composition of the resin of the resin particle (n) is formed on the surface of the resin particle (n)) A method for forming a coating layer (n + 1) made of different resins) will be described.

Here, when the resin particles (n) are core particles (n = 1), a “two-stage polymerization method” is performed. When the resin particles (n) are composite resin particles (n ≧ 2), It becomes a multi-stage polymerization method of three or more stages.

複合 In the composite resin particles obtained by the multi-stage polymerization method, a plurality of resins having different compositions and / or molecular weights exist. Therefore, the toner obtained by salting out, aggregating, and fusing the composite resin particles and the colorant particles has extremely small variations in composition, molecular weight, and surface characteristics among the toner particles.

According to such a toner having a uniform composition, molecular weight, and surface characteristics among toner particles, good adhesion (high fixing strength) to an image support is maintained in an image forming method including a fixing step by a contact heating method. Meanwhile, the offset resistance and the anti-winding property can be improved, and an image having an appropriate gloss can be obtained.

Specifically showing an example of a method for producing toner particles according to the present invention,
(1) a polymerization step for obtaining resin particles,
(2) salting out, aggregating, and fusing the resin particles and the colorant particles to obtain toner particles (II);
(3) a filtration and washing step of filtering the toner particles from the dispersion system of the toner particles and removing a surfactant and the like from the toner particles;
(4) a drying step of drying the washed toner particles;
And (5) a step of adding an external additive to the dried toner particles.

Hereinafter, each step will be described.

As a method of including the release agent in the resin particles (core particles), the release agent is dissolved in a monomer, the resulting monomer solution is dispersed in oil droplets in an aqueous medium, and this system is subjected to polymerization treatment. Thereby, a method of obtaining latex particles can be adopted.

The step (II) of salting out, coagulation and fusion is performed by salting out, coagulation and fusion of the resin particles obtained in the polymerization step (I) and the colorant particles (simultaneously with salting out and fusion). Is a process of obtaining non-spherical toner particles.

In the salting-out, agglomeration, and fusion step (II), together with the composite resin particles and the colorant particles, a releasing agent such as an ester wax, and an internal additive particle such as a charge control agent (the number average primary particle diameter is 10%). (Fine particles having a size of about 1000 nm) may be added, and then salted out, aggregated, and fused.

Colorant particles may be surface-modified. Here, conventionally known surface modifiers can be used.

The colorant particles are subjected to salting out, coagulation, and fusion treatment in a state of being dispersed in an aqueous medium. Examples of the aqueous medium in which the colorant particles are dispersed include an aqueous solution in which a surfactant is dissolved at a concentration equal to or higher than the critical micelle concentration (CMC).

に As the surfactant, the same surfactant as that used in the multi-stage polymerization step (I) can be used.

The disperser used for the dispersion treatment of the colorant particles is not particularly limited, but is preferably a stirrer “CLEARMIX” (manufactured by M Technique Co., Ltd.) equipped with a high-speed rotating rotor, an ultrasonic disperser, Examples include a pressure disperser such as a mechanical homogenizer, a Manton-Gaulin, a pressure homogenizer, and a medium disperser such as a Getzman mill and a diamond fine mill.

In order to salt out, agglomerate, and fuse the resin particles and the colorant particles, in a dispersion in which the resin particles and the colorant particles are dispersed, a coagulant having a critical aggregation concentration or higher is added, and the dispersion is performed. The liquid is preferably heated to a temperature equal to or higher than the glass transition temperature (Tg) of the resin particles.

More preferably, an aggregation terminator is used at the stage when the composite resin particles reach a desired particle size by the aggregation agent. As the aggregation terminator, a monovalent metal salt, particularly, sodium chloride is preferably used.

(4) The temperature range suitable for salting out, agglomeration, and fusion is (Tg + 10) to (Tg + 50 ° C.), and particularly preferably (Tg + 15) to (Tg + 40 ° C.). In addition, an organic solvent that is infinitely soluble in water may be added in order to effectively perform fusion.

Here, examples of the “coagulant” used in salting out, coagulation, and fusion include the above-described alkali metal salts and alkaline earth metal salts.

塩 The salting out and aggregation according to the present invention will be described.

In the present invention, “salting out, agglomeration and fusion” means that salting out (aggregation of particles) and fusion (loss of interface between particles) occur simultaneously, or that salting out and fusion occur simultaneously. The act of causing

In order to simultaneously carry out the salting-out and the fusion, it is preferable that the particles (composite resin particles, colorant particles) are aggregated under a temperature condition not lower than the glass transition temperature (Tg) of the resin constituting the composite resin particles. .

重合 Thus, by performing the preparation of the resin particles in a system in which no colorant is present, the polymerization reaction for obtaining the composite resin particles is not hindered. For this reason, according to the toner of the present invention, excellent offset resistance is not impaired, and contamination of the fixing device and image contamination due to accumulation of toner do not occur.

In addition, as a result of reliably performing the polymerization reaction for obtaining the composite resin particles, no monomer or oligomer remains in the obtained toner particles, and the heat fixing step of the image forming method using the toner. Does not cause off-flavors.

Further, the surface characteristics of the obtained toner particles are uniform and the charge amount distribution is sharp, so that an image having excellent sharpness can be formed over a long period of time. According to such a toner having a uniform composition, molecular weight, and surface characteristics among toner particles, good adhesion (high fixing strength) to an image support is maintained in an image forming method including a fixing step by a contact heating method. Meanwhile, the offset resistance can be improved, and an image having an appropriate gloss can be obtained.

Examples of the resin used for forming the resin particles described above include a thermoplastic binder resin, and specifically, a homopolymer or a copolymer of styrenes such as styrene and α-methylstyrene (styrene). Methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, methacrylic acid Homopolymer or copolymer (vinyl resin) of an ester having a vinyl group such as lauryl or 2-ethylhexyl methacrylate (vinyl resin); homopolymer or copolymer of a vinyl nitrile such as acrylonitrile or methacrylonitrile (vinyl resin) Resins); vinyl methyl ether, vinyl isobutyl ether, etc. Homopolymers or copolymers of vinyl ethers (vinyl resins); homopolymers or copolymers of vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone (vinyl resins); ethylene, propylene, Homopolymers or copolymers of olefins such as butadiene and isoprene (olefin resins); non-vinyl condensation resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins and polyether resins; Examples include a graft polymer of a non-vinyl condensation resin and a vinyl monomer. These resins may be used alone or in combination of two or more.

ビ ニ ル Among these resins, vinyl resins are particularly preferred. A vinyl resin is advantageous in that a resin particle dispersion can be easily prepared by emulsion polymerization or seed polymerization using an ionic surfactant or the like. Examples of the vinyl monomer include acrylic acid, methacrylic acid, maleic acid, cinnamic acid, fumaric acid, vinyl sulfonic acid, ethylene imine, vinyl pyridine, vinyl polymer acid such as vinyl amine and vinyl polymer base. Examples of the starting material include monomers. In the present invention, the resin particles preferably contain the vinyl monomer as a monomer component. In the present invention, among these vinyl monomers, vinyl polymer acids are more preferable in terms of easiness of a reaction for forming a vinyl resin, and specific examples thereof include acrylic acid, methacrylic acid, maleic acid, and cinnamic acid. Dissociable vinyl monomers having a carboxyl group as a dissociating group, such as acid and fumaric acid, are particularly preferred in terms of controlling the degree of polymerization and the glass transition point.

The concentration of the dissociating group in the dissociable vinyl monomer can be determined by, for example, dissolving particles such as toner particles from the surface as described in Polymer Latex Chemistry (Polymer Publishing Association). Can be determined. In addition, the molecular weight and the glass transition point of the resin from the surface to the inside of the particles can also be determined by the above method and the like.

The number average particle diameter of the resin particles is usually at most 1 μm (1 μm or less), preferably 0.01 to 1 μm. When the number average particle size exceeds 1 μm, the particle size distribution of the finally obtained toner is widened, or free particles are generated, and the performance and reliability are easily lowered. On the other hand, when the number average particle size is within the above range, the above-mentioned disadvantages are eliminated, and uneven distribution among toners is reduced, dispersion in toner particles is improved, and variations in performance and reliability are advantageously reduced. is there. The number average particle size can be measured using, for example, a Coulter counter.

(4) The colorant dispersion is obtained by dispersing at least a colorant. Examples of the coloring agent include carbon black, chrome yellow, Hansa yellow, benzidine yellow, slen yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliant carmine 3B, and brilliant carmine 6B. , DuPont Oil Red, Pyrazolone Red, Risor 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 Pigments: acridine, xanthene, azo, benzoquinone, azine, anthraquinone, dioxa And various dyes such as thiazine, azomethine, indico, thioindico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, thiazine, thiazole, and xanthene dyes. . These colorants may be used alone or in combination of two or more.

The number average particle size of the colorant is usually at most 1 μm (ie, 1 μm or less), preferably at most 0.5 μm (ie, 0.5 μm or less), particularly preferably 0.01 to 0.5 μm. When the number average particle size exceeds 1 μm, the particle size distribution of the finally obtained toner particles is widened, or free particles are generated, which tends to cause deterioration in performance and reliability. On the other hand, when the number average particle size is within the above range, the above-mentioned disadvantages are eliminated, the uneven distribution between toner particles is reduced, the dispersion in the toner particles is improved, and the dispersion in performance and reliability is reduced. It is. Further, when the number average particle diameter is 0.5 μm or less, the obtained toner particles are advantageous in that they are excellent in color development, color reproducibility, OHP transparency and the like. The number average particle size can be measured using, for example, a microtrack.

ト ナ ー It is preferable that the toner particles according to the present invention contain a release agent.

As the release agent, known compounds and compounds represented by the following general formula can be used, and among these, compounds represented by the following general formula are preferable.

General formula R ^1- (OCO-R ² ) _n
n is an integer of 1 to 4, preferably 2 to 4, more preferably 3 to 4, and particularly preferably 4.

R ¹ and R ² represent a hydrocarbon group which may have a substituent.

R ¹ preferably has 1 to 40 carbon atoms, more preferably has 1 to 20 carbon atoms, and particularly preferably has 2 to 5 carbon atoms.

R ² preferably has 1 to 40 carbon atoms, more preferably 16 to 30 carbon atoms, and particularly preferably 18 to 26 carbon atoms.

<4> Representative representative compounds are described below.

The amount of the release agent added is preferably 1 to 30% by mass, more preferably 3 to 25% by mass, based on the whole toner particles.

In addition, the toner particles according to the present invention may contain an antistatic agent.

Examples of the charge control agent include a quaternary ammonium salt compound, a nigrosine compound, a dye composed of a complex of aluminum, iron, chromium, and the like, and a triphenylmethane pigment.

<< Preparation of toner >>
The toner of the present invention can be prepared by mixing an external additive such as metal oxide particles with the toner particles. The apparatus to be prepared is not particularly limited, and can be performed using a known apparatus. Specific examples include various mixing apparatuses such as a turbular mixer, a Henschel mixer, a Nauta mixer, and a V-type mixer. it can. Of these devices, the Henschel mixer is preferred.

量 The amount of the external additive added to the toner particles is preferably 0.1 to 4% by mass, more preferably 0.5 to 2% by mass, based on the toner particles.

公 知 As the external additive, a known external additive can be used in addition to the metal oxide particles according to the present invention.

As the known external additives, fine particles of titanium oxide, alumina and the like (specific surface area by nitrogen adsorption measured by the BET method of 50 to 400 m ² / g), organic fine particles and the like can be used.

Examples of the titanium oxide fine particles include commercially available products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., and commercially available products MT-100S, MT-100B, MT-500BS, MT-600, MT-600SS, and JA manufactured by Teica. -1, commercial products TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T manufactured by Fuji Titanium Co., Ltd., commercial products IT-S, IT-OA, IT-OB, IT manufactured by Idemitsu Kosan Co., Ltd. —OC and the like.

Examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd., and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.

Moreover, as the organic fine particles, spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm can be used. As this, a homopolymer such as styrene or methyl methacrylate or a copolymer thereof can be used.

で は In the present invention, a lubricant as an external additive may be added. For example, salts of zinc, aluminum, copper, magnesium, calcium, etc. of stearic acid, salts of zinc, manganese, iron, copper, magnesium, etc. of oleic acid, salts of zinc, copper, magnesium, calcium, etc. of palmitic acid, linoleic acid Metal salts of higher fatty acids, such as salts of zinc, calcium and the like, and salts of zinc, calcium and the like of ricinoleic acid, but are not limited thereto.

《Developer》
The toner of the present invention can be used as a one-component developer or a two-component developer, but is preferably used as a two-component developer.

When used as a one-component developer, there is a method in which the toner is used as it is as a non-magnetic one-component developer, but usually, magnetic particles of about 0.1 to 5 μm are contained in toner particles to form a one-component magnetic developer. Used. As a method of containing the same, it is common to include the same in the toner particles as in the case of the colorant.

In addition, when used as a two-component developer by being mixed with a carrier that is a magnetic particle, as the magnetic particle, a metal such as iron, ferrite, magnetite, or an alloy of such a metal with a metal such as aluminum or lead is used. Known materials can be used. Among these, ferrite particles are preferred. The volume average particle size of the carrier is preferably from 15 to 100 μm, more preferably from 25 to 60 μm.

体積 Typically, the volume average particle size of the carrier can be measured by a laser diffraction type particle size distribution analyzer “Heros” (manufactured by Sympathic Co., Ltd.) equipped with a wet disperser.

As the carrier, a carrier in which magnetic particles are further coated with a resin or a so-called resin-dispersed carrier in which magnetic particles are dispersed in a resin can also be used. The resin composition for coating is not particularly limited, but, for example, an olefin resin, a styrene resin, a styrene / acrylic resin, a silicone resin, an ester resin, or a fluorine-containing polymer resin is used. Further, the resin for constituting the resin dispersion type carrier is not particularly limited, and a known resin can be used. For example, a styrene / acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to.

Next, an image forming method will be described.

《Image forming method》
According to the image forming method of the present invention, a toner image composed of toner is formed on an image forming support (photoreceptor), and the toner image is formed between a heating member (heating roller) and a pressing member (pressure roller). And fixing the toner image on the image forming support by passing the toner image through the support.

FIG. 4 is a sectional view of an image forming apparatus showing an example of an image forming method using the toner of the present invention.

The image forming apparatus shown in FIG. 4 is a digital image forming apparatus, and includes an image reading unit A, an image processing unit B (not shown), an image forming unit C, and a transfer paper transport unit D as a transfer paper transport unit. It is configured.

An automatic document feeder for automatically transporting a document is provided above the image reading unit A. The document placed on the document placing table 111 is separated and transported one by one by a document transport roller 112, and is moved to a reading position 113a. Image is read. The document for which reading of the document has been completed is discharged onto the document discharge tray 114 by the document conveying roller 112.

On the other hand, when the image of the original placed on the platen glass 113 is read by the speed v of the first mirror unit 115 including the illumination lamp and the first mirror constituting the scanning optical system, and the V-shaped Reading is performed by moving the second mirror unit 116 including the second mirror and the third mirror in the same direction at the speed v / 2.

(4) The read image is formed on the light receiving surface of the image sensor CCD, which is a line sensor, through the projection lens 117. The linear optical image formed on the image sensor CCD is sequentially subjected to A / D conversion after being photoelectrically converted into an electric signal (luminance signal), and subjected to processing such as density conversion and filter processing in an image processing unit B. After that, the image data is temporarily stored in the memory.

In the image forming unit C, as an image forming unit, a drum-shaped photoconductor (hereinafter, also referred to as a photoconductor drum) 121 serving as an image carrier, a charger 122 serving as a charging unit, and a developing unit serving as a developing unit are provided around the periphery thereof. An apparatus 123, a transfer unit 124 as a transfer unit, a separator 125 as a separation unit, a cleaning device (blade cleaning) 126, and a PCL (precharge lamp) 127 are arranged in the order of operation. The photoreceptor 121 is formed by applying a photoconductive compound on a drum substrate. For example, an organic photoreceptor (OPC) is preferably used, and is driven to rotate clockwise in the drawing.

(4) After the rotating photoconductor 121 is uniformly charged by the charger 122, the exposure optical system 130 performs image exposure based on the image signal called from the memory of the image processing unit B. The exposure optical system 130, which is a writing unit, uses a laser diode (not shown) as a light emission source, passes through a rotating polygon mirror 131, an fθ lens (no sign), and a cylindrical lens (no sign), and the optical path is bent by a reflection mirror 132 to perform main scanning. The image exposure is performed on the photoconductor 121 at the position Ao, and a latent image is formed by rotation (sub-scan) of the photoconductor 121. In an example of the present embodiment, a latent image is formed by exposing a character portion.

The latent image on the photoconductor 121 is subjected to reversal development by the developing device 123, and a visible toner image is formed on the surface of the photoconductor 121. In the transfer paper transport section D, paper feed units 141 (A), 141 (B), and 141 (C) are provided below the image forming unit as transfer paper storage means in which transfer papers P of different sizes are stored. A manual paper feed unit 142 for performing manual paper feed is provided on the side, and the transfer paper P selected from any of them is fed along a transport path 140 by guide rollers 143, and is fed. The transfer paper P is temporarily stopped by a pair of registration rollers 144 that corrects the inclination and deviation of the transfer paper to be fed, and then re-fed, and guided to the transport path 140, the pre-transfer roller 143a, and the transfer entrance guide plate 146. Then, the toner image on the photoconductor 121 is transferred to the transfer paper P by the transfer device 124 at the transfer position Bo, and then the charge is removed by the separator 125 so that the transfer paper P is removed from the surface of the photoconductor 121. Separated, it is conveyed to the fixing device 150 by a conveying device 145.

The fixing device 150 has a heating roller 151 and a pressure roller 152. The transfer paper P is passed between the heating roller 151 and the pressure roller 152, and the toner is fused by heating and pressing. . The transfer paper P on which the toner image has been fixed is discharged onto the discharge tray 164.

す る Hereinafter, the present invention will be described specifically with reference to examples, but embodiments of the present invention are not limited thereto.

Example 1
《Manufacture of metal oxide particles》
The apparatus shown in FIG. 2 was used for producing metal oxide particles.

The raw material liquid prepared by mixing the raw materials shown in Table 1 at room temperature is supplied to a burner provided at the top of the vertical combustion furnace, and the fine liquid is sprayed from the spray nozzle attached to the tip of the burner by the air of the spray medium. It was sprayed as drops and burned with an auxiliary flame from the combustion of propane. Oxygen and air were supplied from the burner as the supporting gas.

“Metal oxide particles 1 to 7” and “Comparative metal oxide particles 1 to 4” were prepared by adjusting the supply amount of the raw material liquid prepared from the raw materials described in Table 1 to 5 to 8 kg / HR and spraying air to 1 to 7 Nm. ³ / HR, the propane amount is controlled to 0.4 Nm ³ / HR, the supply amount of oxygen air is controlled to 15 to 184 Nm ³ / HR, the flame temperature is adjusted to 2500 ° C., and combustion is performed. Manufactured.

The presence / absence of the domain matrix structure of the metal oxide particles produced above, the average primary particle diameter of the particles, and the average Feret horizontal diameter based on the number of domains are observed using a transmission electron microscope. (Manufactured by Nireco Co., Ltd.).

個数 Further, the number% of domains in the metal oxide particles was determined by a fluorescent X-ray analysis method, and specifically, a fluorescent X-ray analyzer manufactured by Rigaku Denki Kogyo KK was used.

Table 1 shows the raw materials used for producing the metal oxide particles, and Table 2 shows the physical property values of the obtained metal oxide particles.

Example 2
<< Manufacture of Toner 1 >>
(Preparation of latex (1HML))
(1) Preparation of core particles (first-stage polymerization): Anionic surfactant (101) is placed in a 5000 ml separable flask equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device.
_{(101) C 10 H 21 (} OCH 2 CH 2) 2 OSO 3 Na
A surfactant solution (aqueous medium) prepared by dissolving 7.08 parts by mass of ion-exchanged water in 3010 parts by mass was charged, and the temperature in the flask was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. Was.

To this surfactant solution was added an initiator solution obtained by dissolving 9.2 parts by mass of a polymerization initiator (potassium persulfate: KPS) in 200 parts by mass of ion-exchanged water. 0.1 part by mass, a monomer mixture of 19.9 parts by mass of n-butyl acrylate and 10.9 parts by mass of methacrylic acid were added dropwise over 1 hour, and the system was heated and stirred at 75 ° C. for 2 hours. Then, polymerization (first-stage polymerization) was performed to prepare a latex (a dispersion of resin particles composed of a high molecular weight resin). This is designated as “latex (1H)”.

(2) Formation of an intermediate layer (second stage polymerization); In a flask equipped with a stirrer, 105.6 parts by mass of styrene, 30.0 parts by mass of n-butyl acrylate, 6.2 parts by mass of methacrylic acid, n- A compound represented by the above formula (19) (hereinafter, also referred to as “exemplary compound (19)”) as a crystalline substance in a monomer mixture solution composed of 5.6 parts by mass of octyl-3-mercaptopropionate. 9) parts by mass were added, and the mixture was heated to 90 ° C. and dissolved to prepare a monomer solution.

On the other hand, a surfactant solution prepared by dissolving 1.6 parts by mass of an anionic surfactant (formula (101)) in 2700 ml of ion-exchanged water is heated to 98 ° C., and the dispersion of the core particles is performed in the surfactant solution. After adding 28 parts by mass of the latex (1H), which is a liquid, in terms of solid content, a mechanical dispersing machine “CLEARMIX (CLEARMIX)” having a circulation path (manufactured by M Technic Co., Ltd.) was used to prepare the above-mentioned compound ( The monomer solution of 19) was mixed and dispersed for 8 hours to prepare a dispersion liquid (emulsion liquid) containing emulsified particles (oil droplets).

Next, to this dispersion liquid (emulsion liquid) were added an initiator solution obtained by dissolving 5.1 parts by mass of a polymerization initiator (KPS) in 240 ml of ion-exchanged water, and 750 ml of ion-exchanged water. Polymerization (second-stage polymerization) by heating and stirring for 12 hours at, to obtain a latex (a dispersion of composite resin particles having a structure in which the surface of resin particles composed of a high molecular weight resin is coated with an intermediate molecular weight resin). Was. This is referred to as “latex (1HM)”.

(4) The latex (1HM) was dried and observed with a scanning electron microscope. As a result, particles (400 to 1000 nm) mainly composed of the exemplary compound (19) not surrounded by the latex were observed.

(3) Formation of outer layer (third stage polymerization): an initiator solution in which 7.4 parts by mass of a polymerization initiator (KPS) is dissolved in 200 ml of ion-exchanged water in the latex (1HM) obtained as described above. And at a temperature of 80 ° C., 300 parts by mass of styrene, 95 parts by mass of n-butyl acrylate, 15.3 parts by mass of methacrylic acid, and 10.4 parts by mass of n-octyl-3-mercaptopropionate. The monomer mixture was added dropwise over 1 hour. After the completion of the dropping, polymerization (third stage polymerization) is carried out by heating and stirring for 2 hours, and then cooled to 28 ° C., and a latex (a central portion composed of a high molecular weight resin, an intermediate layer composed of an intermediate molecular weight resin, A dispersion liquid of composite resin particles having an outer layer made of a molecular weight resin and the intermediate layer containing the exemplified compound (19). This latex is referred to as “latex (1HML)”.

The composite resin particles constituting this “latex (1HML)” have peak molecular weights of 138,000, 80,000 and 13,000, and the mass average particle diameter of the composite resin particles is 122 nm. Was.

59.0 parts by mass of the anionic surfactant (101) was dissolved in 1600 ml of ion-exchanged water while stirring, and 420.0 parts by mass of carbon black “REGAL 330” (manufactured by Cabot) was gradually added while stirring the solution. Then, a dispersion of colorant particles (hereinafter, also referred to as “colorant dispersion 1”) was prepared by performing dispersion treatment using “CLEARMIX” (manufactured by M Technique Co., Ltd.). The particle diameter of the colorant particles in this colorant dispersion was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), and as a result, the mass average particle diameter was 89 nm.

420.7 parts by mass of “latex (1HML)” (in terms of solid content), 900 parts by mass of ion-exchanged water, and 166 parts by mass of “colorant dispersion liquid 1” were subjected to a temperature sensor, a cooling pipe, a nitrogen introduction device, The mixture was stirred in a reaction vessel (four-necked flask) equipped with a stirrer. After adjusting the temperature in the container to 30 ° C., a 5 mol / L aqueous sodium hydroxide solution was added to the solution to adjust the pH to 10.0.

Next, an aqueous solution in which 12.1 parts by mass of magnesium chloride hexahydrate was dissolved in 1,000 ml of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, heating was started, and the temperature of the system was raised to 90 ° C. over 6 to 60 minutes to form associated particles. In this state, the particle size of the associated particles was measured with a “Coulter counter TA-II”, and when the number average particle size became 4 μm, an aqueous solution in which 80.4 parts by mass of sodium chloride was dissolved in 1,000 ml of ion-exchanged water Was added to stop the grain growth, and the mixture was heated and stirred at a liquid temperature of 98 ° C. for 2 hours as an aging treatment, whereby the fusion of the grains and the phase separation of the crystalline substance were continued.

Thereafter, the mixture was cooled to 30 ° C., the pH was adjusted to 4.0 by adding hydrochloric acid, and the stirring was stopped. The generated associated particles were subjected to solid-liquid separation using a basket-type centrifuge “MARKIII Model No. 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a cake of toner particles. The cake of the toner particles is washed with water in the basket type centrifugal separator, then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.), and dried until the water content becomes 0.5% by mass. 1 "was obtained. To 100 parts by mass of the “toner particles 1”, 1.0 part by mass of “metal oxide particles 1” shown in Table 1 and 0.6 parts by mass of hydrophobic silica having a primary particle diameter of 12 nm were added, and mixed with a “Henschel mixer”. Thereafter, coarse particles were removed using a sieve having 45 μm openings to obtain “Toner 1”.

<< Manufacture of Toner 2 >>
(Preparation of resin fine particle dispersion)
A mixture of 370 parts by mass of styrene, 30 parts by mass of n-butyl acrylate, 8 parts by mass of acrylic acid, 24 parts by mass of dodecanethiol and 4 parts by mass of carbon tetrabromide dissolved therein, 6 parts by mass of a nonionic surfactant and Emulsion polymerization was performed in a flask in which 10 parts by mass of an anionic surfactant (dodecyl) was dissolved in 550 parts by mass of ion-exchanged water, and while slowly mixing for 10 minutes, 50 parts by mass of ion-exchanged water in which 4 parts by mass of ammonium persulfate was dissolved. Part was introduced. After purging with nitrogen, the contents in the flask were heated in an oil bath until the temperature reached 70 ° C. while stirring, and the emulsion polymerization was continued for 5 hours. As a result, a resin fine particle dispersion in which resin particles having a diameter of 150 nm, a T mass part of 58 ° C., and a mass average molecular weight Mw of 11,500 were dispersed was obtained. The solid content concentration of this dispersion was 40% by mass.

(Preparation of release agent dispersion)
100 parts by mass of paraffin wax (HNP0190: manufactured by Nippon Seiro Co., Ltd., melting point 85 ° C.)
5 parts by mass of cationic surfactant (Sanisol B50: manufactured by Kao Corporation)
240 parts by mass of ion-exchanged water The above components were dispersed in a round stainless steel flask using a homogenizer “Ultra Turrax T50” (manufactured by IKA) for 10 minutes, and then dispersed using a pressure discharge type homogenizer. "Release agent dispersion liquid 2" in which release agent particles having a particle size of 550 nm were dispersed was prepared.
(Preparation of aggregated particles)
Resin fine particle dispersion 234 parts Colorant dispersion 1 40 parts Release agent dispersion 2 40 parts Polyaluminum chloride 1.8 parts Ion-exchanged water 600 parts The above components were mixed in a round stainless steel flask with a homogenizer “Ultra Turrax”. After mixing and dispersing using T50 "(manufactured by IKA), the mixture was heated to 55 ° C. while stirring the inside of the flask in a heating oil bath. After holding at 55 ° C. for 30 minutes, it was confirmed that aggregated particles having a D50 of 4.8 μm were formed. Further, the temperature of the additional oil bath was raised and maintained at 56 ° C. for 2 hours, and D50 became 5.9 μm. Then, after adding 32 parts by mass of the resin particle dispersion to the dispersion containing the aggregated particles, the temperature of the oil bath for heating was raised to 55 ° C. and maintained for 30 minutes. The dispersion containing the aggregated particles, 1N sodium hydroxide was added to adjust the pH of the system to 5.0, then the stainless steel flask was sealed, and heated to 95 ° C. while continuing to stir using a magnetic seal. Then, it was kept for 6 hours and cooled to room temperature. Thereafter, solid-liquid separation was performed using a basket-type centrifuge “MARK III Model No. 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a cake of toner particles. The cake of the toner particles is washed with water in the basket type centrifugal separator, then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.), and dried until the water content becomes 0.5% by mass. 2 "was obtained. To 100 parts by mass of the “toner particles 2”, 1.0 part by mass of “metal oxide particles 2” shown in Table 1 and 0.6 part by mass of hydrophobic silica having a primary particle diameter of 12 nm were added, and mixed with a “Henschel mixer”. Thereafter, coarse particles were removed using a sieve having 45 μm openings to obtain “Toner 2”.

<< Manufacture of Toner 3 >>
Styrene = 165 parts by mass, n-butyl acrylate = 35 parts by mass, carbon black = 10 parts by mass, metal di-t-butylsalicylate = 2 parts by mass, styrene-methacrylic acid copolymer = 8 parts by mass, paraffin wax ( (mp = 70 ° C.) = 20 parts by mass was heated to 60 ° C. and uniformly dissolved and dispersed at 12,000 rpm with a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). Azobis (2,4-valeronitrile) = 10 parts by mass was added and dissolved to prepare a polymerizable monomer composition.

Then, 450 parts by mass of a 0.1 M sodium phosphate aqueous solution was added to 710 parts by mass of ion-exchanged water, and 68 parts by mass of 1.0 M calcium chloride was gradually added while stirring at 13000 rpm with a TK homomixer to disperse tricalcium phosphate. A suspension was prepared. The polymerizable monomer composition was added to the suspension, and the mixture was stirred with a TK homomixer at 10,000 rpm for 20 minutes to granulate the polymerizable monomer composition.

Thereafter, the reaction was carried out at 75 to 95 ° C for 5 to 15 hours using a commercially available polymerization reactor. Tricalcium phosphate was dissolved and removed with hydrochloric acid. Thereafter, solid-liquid separation was performed using a basket-type centrifuge “MARKIII Model No. 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a cake of toner particles. The cake of the toner particles is washed with water in the basket type centrifugal separator, then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.), and dried until the water content becomes 0.5% by mass. 3 "was obtained. To 100 parts by mass of the “toner particles 3”, 1.0 part by mass of “metal oxide particles 3” described in Table 1 and 0.6 part by mass of hydrophobic silica having a primary particle diameter of 12 nm were added, and mixed with a “Henschel mixer”. Thereafter, coarse particles were removed using a sieve having 45 μm openings to obtain “Toner 3”.

<< Manufacture of Toner 4 >>
(Preparation of toner dispersion)
8 parts by mass of polyvinyl butyral (polyvinyl acetate unit: 2% by mass, polyvinyl alcohol unit: 19% by mass, polyvinyl acetal unit: 79% by mass, average degree of polymerization: 630)
A mixture of 300 parts by weight of 2-methyl-2-butanol, 82 parts by weight of styrene and 18 parts by weight of n-butyl acrylate was sufficiently dissolved, and 7 parts by weight of carbon black and 500 parts by weight of glass beads (1 mm in diameter) were added. After stirring with a paint shaker for 6 hours, the glass beads were removed with a mesh.

While maintaining a polymerization vessel equipped with a mechanical stirrer and an inlet tube for nitrogen bubbling at 15 ° C., 300 parts by mass of the obtained dispersion and 3.6 parts of 2,2′-azobisisobutyronitrile were added thereto. Parts by mass were gradually added to form a polymerization reaction system. At this time, the pigment dispersion ratio 重合 of the polymerization reaction system was 1.01. The amount of dissolved oxygen in the polymerization reaction system was 8.2 m parts / liter.

(4) While maintaining the polymerization reaction system at 20 ° C., nitrogen was bubbled into the liquid until the amount of dissolved oxygen in the polymerization reaction system reached 0.2 m mass parts / liter. This was heated to 75 ° C. and polymerized for 12 hours with stirring. Nitrogen bubbling was continued during the polymerization.

後 After the completion of the reaction, the resultant was cooled to 20 ° C. while stirring. Thereafter, solid-liquid separation was performed using a basket-type centrifuge “MARKIII Model No. 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a cake of toner particles. The cake of the toner particles is washed with water in the basket type centrifugal separator, then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.), and dried until the water content becomes 0.5% by mass. 4 "was obtained. To 100 parts by mass of the “toner particles 4”, 1.0 part by mass of “metal oxide particles 4” described in Table 1 and 0.6 part by mass of hydrophobic silica having a primary particle diameter of 12 nm were added and mixed with a “Henschel mixer”. Thereafter, coarse particles were removed using a sieve having 45 μm openings to obtain “Toner 4”.

<< Manufacture of Toner 5 >>
(Preparation of pigment dispersion)
50 parts of polyester resin (T parts by mass; 60 ° C, softening point; 98 ° C, mass average molecular weight; 18000)
Carbon black 50 parts Ethyl acetate 100 parts Glass beads were added to the dispersion of the above-mentioned material composition, and the mixture was mounted on a sand mill disperser.

分散 While cooling around the dispersion container, the mixture was dispersed in a high-speed stirring mode for 3 hours and diluted with ethyl acetate to prepare a “colorant dispersion 5” having a colorant concentration of 15% by mass.

(Preparation of micronized wax)
Paraffin wax: (melting point: 85 ° C.) 15 parts Toluene 85 parts The above-mentioned materials were charged into a dispersing machine having a function of circulating a heating medium around a vessel equipped with stirring blades. The temperature was gradually increased while stirring at 83 revolutions per minute, and finally, the mixture was stirred at 100 ° C. for 3 hours. Next, the mixture was cooled to room temperature at a rate of about 2 ° C. per minute while stirring was continued to precipitate wax in the form of fine particles. This wax dispersion was again dispersed under high pressure using a high-pressure emulsifier “APVAULIN HOMOGENEZER 15MR type”. When the wax particle size was measured in the same manner, it was 0.69 μm. The dispersion liquid of the prepared micronized wax was diluted with ethyl acetate so that the mass concentration of the wax became 15% by mass.

(Preparation of oil phase)
85 parts of polyester resin (glass transition point; 60 ° C, softening point; 98 ° C, mass average molecular weight; 18000)
Colorant Dispersion 2 50 parts Microparticulate wax dispersion: (wax concentration 15% by mass) 33 parts Ethyl acetate 32 parts The oil phase of the above material composition was prepared after confirming that the polyester resin was sufficiently dissolved. The above oil phase was charged into a homomixer “Ace Homogenizer” (manufactured by Nippon Seiki Co., Ltd.), and stirred at 16,000 rpm for 2 minutes to prepare a uniform oil phase.

(Preparation of aqueous phase)
Calcium carbonate: (average particle size 0.03 μm) 60 parts Pure water 40 parts The aqueous calcium carbonate solution obtained by stirring the above materials for 4 days in a ball mill was used as the aqueous phase.

平均 The average particle size of calcium carbonate measured using a laser diffraction / scattering particle size distribution analyzer “LA-700” (Horiba, Ltd.) was about 0.08 μm.

Carboxymethyl cellulose 2 parts (Selogen BSH; Daiichi Kogyo Pharmaceutical)
Pure water 98 parts Carboxymethylcellulose obtained by stirring the above material with a ball mill was used as an aqueous phase.

(Preparation of spherical particles)
Oil phase 55 parts Aqueous phase (aqueous calcium carbonate solution) 15 parts Aqueous phase (aqueous carboxymethyl cellulose solution) 30 parts The above materials are charged into a colloid mill (manufactured by Nippon Seiki Co., Ltd.), and a gap interval of 1.5 mm is performed at 9,400 revolutions per minute for 40 minutes. Emulsification was performed. Next, the above emulsion was put into a rotary evaporator, and the solvent was removed under reduced pressure at room temperature of 4 kPa for 3 hours. Thereafter, 12 M hydrochloric acid was added until the pH reached 2, and calcium carbonate was removed from the surface of the toner particles. Thereafter, 10N sodium hydroxide was added until the pH reached 10, and stirring was continued for 1 hour while stirring in an ultrasonic cleaning tank.

(5) Solid-liquid separation was performed using a basket type centrifuge “MARK III Model No. 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a cake of toner particles. The cake of the toner particles is washed with water in the basket type centrifugal separator, then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.), and dried until the water content becomes 0.5% by mass. 5 "was obtained. To 100 parts by mass of the “toner particles 5”, 1.0 part by mass of “metal oxide particles 5” shown in Table 1 and 0.6 part by mass of hydrophobic silica having a primary particle diameter of 12 nm were added and mixed with a “Henschel mixer”. Thereafter, coarse particles were removed using a sieve having 45 μm openings to obtain “Toner 5”.

<< Manufacture of Toner 6 >>
(Synthesis of polyether resin (A))
Into a high-pressure reactor equipped with a stirrer, a nitrogen inlet tube, a thermometer, and an inlet for raw materials, etc., 0.5 part of potassium hydroxide and 200 parts of toluene as a solvent were put, the pressure in the system was 100 kPa, and the temperature was 40 ° C. While stirring, a mixed solution consisting of 10.8 parts of propylene oxide and 89.2 parts of styrene oxide was injected little by little, and the state of molecular weight change was tracked by terminal group determination, and the number average molecular weight was increased to 7,000. The reaction was stopped when it became. The total amount of the monomers injected at this time was 8.64 parts of propylene oxide and 71.4 parts of styrene oxide. From the obtained polymer solution, toluene and unreacted monomers were distilled off under reduced pressure of 4 kPa to obtain "polyether resin (A)".

18 parts of "polyether resin (A)", 72 parts of polyester resin, and 10 parts of carbon black were converted into a colored resin melt heated to 180 ° C. using a biaxial continuous kneader, and Cavitron CD1010 (U -Rotek continuous dispersion apparatus) at a rate of 100 parts by weight per minute. A separately prepared aqueous medium tank is charged with 0.37% by mass of diluted ammonia water obtained by diluting reagent ammonia water with ion-exchanged water, and heating at 150 ° C. with a heat exchanger at a rate of 0.1 liter per minute. At the same time as the above colored resin melt, the dispersion was transferred to the Cavitron, and under the operating conditions of a rotor rotation speed of 7500 rpm and a pressure of 50 kPa, a colored liquid spherical fine particle-dispersed dispersion at a temperature of 160 ° C. was obtained. Cooled to a temperature of 40 ° C. Thereafter, solid-liquid separation was performed using a basket-type centrifuge “MARKIII Model No. 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a cake of toner particles. The cake of the toner particles is washed with water in the basket type centrifugal separator, then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.), and dried until the water content becomes 0.5% by mass. “Toner particles 6” were obtained. To 100 parts by mass of the “toner particles 6”, 1.0 part by mass of “metal oxide particles 6” shown in Table 1 and 0.6 part by mass of hydrophobic silica having a primary particle diameter of 12 nm were added and mixed with a “Henschel mixer”. Thereafter, coarse particles were removed using a sieve having 45 μm openings to obtain “Toner 6”.

<< Manufacture of Toner 7 >>
(Preparation of polyester resin B)
715.0 g of dimethyl terephthalate, 95.8 g of dimethyl sodium 5-sulfoisophthalate, 526.0 g of propanediol, 48.0 g of diethylene glycol, 247.1 g of dipropylene glycol, and 1.5 g of butyltin hydroxide catalyst It was placed in a polycondensation reactor. The mixture was heated to 190C and the temperature was slowly raised to about 200-202C while collecting methanol by-product in the distillation receiver. Next, the temperature was increased to about 210 ° C. while the pressure was reduced from atmospheric pressure to about 1067 Pa over about 4.5 hours. The product was taken out, and “polyester resin B” having a glass transition temperature of 53.8 ° C. was prepared.

(Preparation of polyester resin dispersion)
Next, 168 g of the “polyester resin B” was added to 1,232 g of deionized water, and stirred at 98 ° C. for 2 hours to prepare a “polyester resin dispersion liquid 7”.

(Meeting process)
In a reactor, 1,400 g of “polyester resin dispersion liquid 7” and 14.22 g of carbon black were added and dispersed. Next, zinc acetate was dissolved in deionized water to prepare a 5% by mass zinc acetate solution. This solution was placed in a reservoir placed on a balance and connected to a pump capable of accurately feeding the zinc acetate solution at 0.01-9.9 ml / min. The amount of zinc acetate required for association of the dispersion is 10% of the resin mass in the dispersion.

加熱 After the dispersion was heated to 56 ° C., the zinc acetate solution was pumped at 9.9 ml / min to start the association. Once 60% by weight of the total amount of zinc acetate (205 g in a 5% by weight solution) has been added, the pump addition rate is reduced to 1.1 ml / min and the amount of zinc acetate is equal to 10% by weight of the resin in the dispersion ( The addition was continued until it reached 335 g (5% by mass solution), and the mixture was stirred at 80 ° C. for 9 hours.

(5) Thereafter, solid-liquid separation was performed using a basket-type centrifuge “MARK III Model No. 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a cake of toner particles. The cake of the toner particles is washed with water in the basket type centrifugal separator, then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.), and dried until the water content becomes 0.5% by mass. 7 "was obtained. To 100 parts by mass of the “toner particles 7”, 1.0 part by mass of “metal oxide particles 1” shown in Table 1 and 0.6 parts by mass of hydrophobic silica having a primary particle diameter of 12 nm were added, and mixed with a “Henschel mixer”. Thereafter, coarse particles were removed using a sieve having 45 μm openings to obtain “Toner 7”.

<< Production of Comparative Toner 1 >>
"Comparative Toner 1" was used in the same manner except that "Comparative Metal Oxide Particle 1" (hereinafter, also referred to as Comparative 1) was used instead of "Metal Oxide Particle 1" used in the production of "Toner 1." I got it.

<< Production of comparative toner 2 >>
"Comparative toner 2" was used in the same manner except that "comparative metal oxide particles 2" (hereinafter, also referred to as comparative 2) were used instead of "metal oxide particles 1" used in the production of "toner 1." I got it.

<< Production of Comparative Toner 3 >>
"Comparative toner 3" was used in the same manner except that "comparative metal oxide particles 3" (hereinafter, also referred to as comparative 3) were used instead of "metal oxide particles 1" used in the production of "toner 1." I got it.

<< Production of comparative toner 4 >>
"Comparative toner 4" was used in the same manner except that "comparative metal oxide particles 4" (hereinafter, also referred to as comparative 4) were used instead of "metal oxide particles 1" used in the production of "toner 1." I got it.

<< Production of comparative toner 5 >>
"Comparative toner 5" was used in the same manner except that "comparative metal oxide particles 4" (hereinafter, also referred to as comparative 5) were used instead of "metal oxide particles 1" used in the production of "toner 1." I got it.

<< Production of comparative toner 6 >>
"Comparative toner 6" was used in the same manner except that "comparative metal oxide particles 4" (hereinafter, also referred to as comparative 6) were used instead of "metal oxide particles 1" used in the production of "toner 1." I got it.

Table 3 shows the physical properties of the obtained toner.

<< Preparation of developer >>
A ferrite carrier coated with a silicone resin and having a volume average particle diameter of 60 μm was mixed with each of “Toner 1 to 7” and “Comparative Toner 1 to 6” prepared above so that the toner concentration became 6% by mass. "Developers 1 to 7" and "Comparative developers 1 to 6" were prepared.

《Evaluation》
The following evaluations were performed on each of “Toners 1 to 7” and “Comparative Toners 1 to 6” prepared above. In addition, the developer corresponding to each toner was used.

As an evaluation machine, a commercially available color printer “C-1616” (manufactured by Fuji Xerox Co., Ltd.) employing an electrophotographic system was modified and used with a photoreceptor having a diameter of 20 mm.

評 価 The cleaning brush for the photoconductor and the cleaning mechanism for the intermediate transfer member were removed for evaluation. Further, in order to clearly evaluate the developer performance, the same toner and developer were set in all four color developing units, and the evaluation was performed.

Fog and image density were measured using a Macbeth reflection densitometer “RD-918” (manufactured by Macbeth Corporation).

<Image fog>
Image fog was determined by the solid white image density. The density of unprinted printing paper (blank paper) is measured at 20 locations based on the absolute image density, and the average value is defined as the blank paper density. Next, the absolute white density was similarly measured at 20 white background portions of the evaluation paper on which the image was formed, and a value obtained by subtracting the white paper density from the average density was evaluated as a solid white image density.

(Evaluation criteria)
◎: Solid white image density of 0.005 or less is good. ：: Solid white image density of 0.006 to 0.008 is a level that is not problematic in practical use. X: Solid white image density is more than 0.009, practical. The top problematic level.

<Spot due to scratches>
The evaluation was made based on how many black spots having a major axis of 0.4 mm or more caused by scratches on the surface of the heating roll per white solid image of A4 size. The major axis of the black spot was confirmed with a microscope equipped with a video printer.

(Evaluation criteria)
◎: 3 black spots of 0.4 mm or more / A4 size or less, good without practical problems ○: 4 to 12 black spots of 0.4 mm or more / A4 size, no problem in practical use x: 0. 13 black spots of 4 mm or more / A4 size or more are practically problematic.

<Transfer at low temperature and low humidity>
A total of 32 sheets of Rank Xerox 200 g paper were printed at low temperature and low humidity (10 ° C., 20% RH). Halftone having a relative density of 0.2 to 0.3 was printed, and the occurrence of mottle due to discharge was visually confirmed at the rear end of the image.

(Evaluation criteria)
◎: No spots due to electric discharge (excellent)
：: There are one or two mottles that cannot be detected without staring (good)
X: Three or more clear spots were generated (poor).

<Charge leak at high temperature and high humidity>
The charge amount of the developer before and after standing for 24 hours at high temperature and high humidity (30 ° C., 85% RH) was measured with a suction-type charge amount measuring device. The difference between the charge amount measured before leaving the developer and the charge amount measured after leaving it at high temperature and high humidity was evaluated as a charge amount leak.

(Evaluation criteria)
：: Charge amount leak is less than 3.0 μC / g and good ○: Charge amount leak is 3.0 to 6.0 μC / g and almost good ×: Charge amount leak is larger than 6.0 μC / g and defective.

<Charge rise at low temperature and low humidity>
50,000 prints were made at low temperature and low humidity (10 ° C., 20% RH), and the charge amount and image density at the start and after the completion of 50,000 prints were measured. The charge amount was measured using a blow-off charge amount measuring device “TB-200” (manufactured by Toshiba Chemical Corporation) by sampling the developer in the four developing devices.

(Evaluation criteria)
A: The charge amount rise is less than 3.0 μC / g at the start and after 50,000 prints, and the decrease in image density is less than 0.01 (excellent)
：: The charge amount rises from 3.0 to 6.0 μC / g at the start and after the end of 50,000 prints, and the decrease in image density is less than 0.04 (good).
×: The increase in the charge amount is larger than 6.0 μC / g at the initial stage and after the completion of 50,000 prints, and the decrease in the image density is 0.04 or more (poor).

<Developer life>
Uses 30,000 print cartridges according to the manufacturer's specifications. The developer is replaced with new cartridges one after another after every 30,000 prints. The endurance test of the developer is continued, and the image quality is visually judged and used. Was determined.

(Evaluation criteria)
：: Print quality does not deteriorate up to a total of 600,000 prints or more, and life is very long and good. ○: Print quality deteriorates with a total of 300,000 to 600,000 prints, but life is long and good. Δ: A total of 60,000 to 290,000 prints. The print quality deteriorates and the service life is rather short. X: The print quality deteriorates with a total of 30,000 to 50,000 prints, and the service life is short.

<Storage stability>
1 g of each toner was placed in a glass sample tube and left in a thermostat at 50 ° C. and 90% RH for 48 hours. Thereafter, the particles were passed through a 28-mesh test sieve, the toner granules remaining on the mesh were weighed, and the storage stability was evaluated based on the granule generation rate.

(Evaluation criteria)
：: Granule generation is less than 10% and storage stability is very good. ：: Granule generation is 10% or more and less than 30% and storage stability is good. X: Granule generation is 30% or more and storage stability is practically problematic.

<Removal of external additives>
The surface of the carrier was observed at a magnification of 40,000 with a commercially available field-effect scanning electron microscope, and the evaluation was made based on the state of the external additive attached to the carrier surface.

(Evaluation criteria)
A: Almost no external additives detached from the toner adhered. A: 2 to 10 external additives detached from the toner are present in an area of 1 μm square, but there is no charge inhibition and there is no practical problem. : 30 or more external additives detached from the toner were present in a 1 μm square area, the charge amount was reduced by 10 μC / g or more by mass compared to the initial stage, and toner scattering and fogging occurred.

<Compatibility with cleanerless process>
The following rank evaluation was performed among 30,000 prints specified by the manufacturer.

(Evaluation criteria)
：: No white stripes due to toner contamination of the charging roller and toner of the transfer roller, and none of the fine lines printed immediately before appear in the next image (excellent)
：: White lines due to toner contamination of the charging roller and toner contamination of the transfer roller could not be detected. In rare cases, the fine line printed immediately before appeared in the next image, but it could not be detected without staring and there was no practical problem (good).
X: White streaks occurred due to toner contamination of the charging roller and toner contamination of the transfer roller. Further, the thin line or the like printed immediately before was clearly detected in the next image (defective).

Table 4 shows the evaluation results.

As is clear from Table 4, the “toner 1 to 7” of the present invention does not generate fog even after repeated printing, can form a good image without black spots, and has a charge amount leak at high temperature and high humidity. There is no increase in the charge amount at low temperature and low humidity, the life of the developer is long, the preservability is good, and excellent properties are obtained without detachment of external additives. In addition, the printer can be downsized because it has high transferability and is compatible with a cleanerless process.

1 is a cross-sectional view of a metal oxide particle having a domain matrix structure. It is a flow figure showing an example of a manufacturing device which manufactures metal oxide particles. FIG. 4 is a diagram illustrating an example of toner particles having no corners. FIG. 2 is a cross-sectional configuration diagram of an image forming apparatus showing an example of an image forming method using the toner of the present invention.

Explanation of reference numerals

1 metal oxide particles 2 matrix as a continuous phase region 3 domain

Claims (9)

In a toner for developing an electrostatic image containing at least a resin, a colorant and metal oxide particles containing two or more metal elements, the metal oxide particles have a domain-matrix structure, and the particles having the domains are made of metal. A toner for developing an electrostatic image, comprising 5 to 49% by number of oxide particles. The electrostatic image developing toner according to claim 1, wherein the matrix of the metal oxide particles is silica. 2. The electrostatic image developing toner according to claim 1, wherein the domain is formed of a titanium compound. 2. The electrostatic image developing toner according to claim 1, wherein the domain is made of an aluminum compound. The toner according to claim 1, wherein the domain comprises a zirconium compound. The average primary particle diameter based on the number of the metal oxide particles is in a range of 10 to 300 nm, and the average horizontal Feret diameter based on the number of the domains is in a range of 1 to 60 nm. For developing electrostatic images. The ratio of toner particles having no corners among the toner particles constituting the toner for developing an electrostatic charge image is 50% by number or more, and the number variation coefficient in the number particle size distribution is 27% or less. Item 4. The toner for developing an electrostatic image according to Item 1. 2. The electrostatic image developing toner according to claim 1, wherein the electrostatic image developing toner is encapsulated or surface-modified with different resin compositions. 3. Forming a toner image composed of an electrostatic image developing toner on an image forming support, and fixing the toner image on the image forming support by passing the toner image between a heating member and a pressing member; 2. An image forming method according to claim 1, wherein said electrostatic image developing toner is the electrostatic image developing toner according to claim 1.

Images