JP2013242495A - Toner for electrostatic charge image development, and electrophotographic image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner for electrostatic charge image development that has good cleanability and charge rising property, and excellent environmental stability, and an electrophotographic image forming method using the toner.SOLUTION: A toner for electrostatic charge image development contains toner base particles containing at least a binder resin, and toner particles containing an external additive. The external additive contains molten silica subjected to hydrophobic treatment with an alkyl alkoxy silane coupling agent represented by the following general formula (1): R-Si(OR); and the number average primary particle diameter of the molten silica is within a range of 60 to 300 nm.

Description

  The present invention relates to an electrostatic image developing toner and an electrophotographic image forming method.

  In recent years, with the spread of digital printing, the demand for image quality of medium and high speed machines and high speed machines is increasing. Along with this, the quality of the developer is required to be higher than before.

  In digital printing, high-quality images are required to be output stably and at high speed. That is, there is a demand for stable images at high speed even when the temperature and humidity environment changes. For this purpose, there is a demand for a developer having stable characteristics even when the temperature and humidity environment changes, such as in a high temperature and high humidity environment or in a low temperature and low humidity environment.

  Conventionally, in order to stably obtain a high-quality image, a toner for developing an electrostatic charge image (hereinafter simply referred to as a toner) is spherical from the viewpoint of improving transferability and cleaning properties as well as improving developability. It is known to add an external additive having a high degree of particle size. For example, Patent Document 1 discloses a technique for improving transferability by using silica produced by a sol-gel method of 80 to 300 nm as an external additive. Patent Document 2 discloses a technique for improving the cleaning property by using silica produced by a sol-gel method as an external additive.

  However, since sol-gel silica is produced by a liquid phase method, it has a high water content due to its manufacturing method. Therefore, when used as an external additive for toner, there is a problem in the rising characteristics of charging and stability against environmental fluctuations. was there.

  Japanese Patent Application Laid-Open No. H10-228688 discloses a technique of using a large particle size silica having a polarity opposite to the charging polarity of the toner as an external additive for the purpose of improving the cleaning property. However, when an external additive having a polarity opposite to that of the toner is used, a charge leaks from the charged toner to the silica having a polarity opposite to that of the toner.

  As described above, the cleaning property and the charge rising property are good, and the environmental stability of the charging property is still not sufficient.

Japanese Patent No. 4390994 JP 2004-53717 A JP 2006-251267 A

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and circumstances, and the problem to be solved thereof is a toner for developing an electrostatic charge image that has good cleaning properties and rising properties of charging, and excellent environmental stability, and the toner. It is an object to provide an electrophotographic image forming method using

  In order to solve the above problems, the present inventor, in the course of studying the cause of the above problems, and the like, a toner using a large particle size fused silica hydrophobized with an alkylalkoxysilane coupling agent as an external additive As a result, it was found that the above problems could be solved, and the present invention was achieved.

  That is, the said subject which concerns on this invention is solved by the following means.

  1. An electrostatic charge image developing toner comprising toner base particles containing at least a binder resin and an external additive, wherein the external additive is at least an alkyl represented by the following general formula (1) A toner for developing electrostatic images, comprising fused silica hydrophobized with an alkoxysilane coupling agent, wherein the fused silica has a number average primary particle size in the range of 60 to 300 nm.

General formula (1)
R ₁ —Si (OR ₂ ) ₃
(In general formula (1), R ₁ represents an alkyl group which may have a substituent having 6 or more carbon atoms, and R ₂ represents an alkyl group having 1 or 2 carbon atoms.)

  2. 2. The electrostatic image developing device according to item 1, wherein the fused silica has a moisture content of less than 3% by mass when the fused silica is left for 48 hours in an environment of 30 ° C. and 80% RH. toner.

  3. 3. The electrostatic image developing toner according to item 1 or 2, wherein the fused silica has an average sphericity of 0.9 to 1.0.

  4). An electrophotographic image forming method for forming an image through at least charging, exposure, development, transfer, and fixing processes, wherein the development process includes any one of items 1 to 3. An electrophotographic image forming method comprising using the toner for developing an electrostatic charge image described above

  By the above means of the present invention, it is possible to provide a toner for developing an electrostatic image having excellent cleaning property and charge rising property and excellent environmental stability, and an electrophotographic image forming method using the toner.

  The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

  Conventionally, it has been known to improve the cleaning property by using spherical large particle diameter silica. However, sol-gel silica having a large particle size is inferior in surface smoothness, so that the fluidity of the toner is lowered when used as an external additive for the toner. When the fluidity of the toner is lowered, the charge rising property is lowered. Moreover, since the sol-gel silica is produced by a liquid phase method, it tends to have a cavity inside, so that the water content becomes high. Therefore, there is a drawback that it is easily affected by moisture.

  The decrease in the charge amount in a high humidity environment is mainly caused by the occurrence of charge leakage starting from the moisture of the toner or external additive. The sol-gel silica has a high water content even if it is hydrophobized from the viewpoint of its production method, so that it becomes a starting point of charge leakage.

  On the other hand, fumed silica (gas phase method), which is a gas combustion method, that is, vaporizes silicon chloride and synthesizes silica fine particles by gas phase reaction in a high-temperature hydrogen flame, is indefinite and may increase the particle size. It has the disadvantage of being difficult.

  On the other hand, the fused silica according to the present invention has a large particle size, good surface properties, and high average sphericity, so that the fluidity of the toner does not deteriorate and the rising of charging is good.

  In addition to the low moisture content of the substrate, the fused silica is heat treated at a high temperature at the time of manufacture, and the silica silanol group is subjected to a hydrophobic treatment with the long-chain alkylalkoxysilane coupling agent of the present invention. Moisture adsorption to the base is reduced, and a high charge amount can be maintained even in a high temperature and high humidity environment. In other words, long-chain alkyl groups with high hydrophobicity are bonded to the outermost surface of silica, and the access of water molecules to unreacted silanol groups is hindered compared to short-chain ones such as hexamethyldisilazane. This is probably because of this.

  As a result, a large particle size fused silica surface-treated with a long-chain alkylalkoxysilane coupling agent is used as an external additive to obtain a toner having good cleaning properties and good rise in charge and excellent environmental stability. Can be considered.

  The toner for developing an electrostatic charge image of the present invention is a toner for developing an electrostatic charge image containing toner particles containing at least a toner base particle containing a binder resin and an external additive, wherein the external additive is at least It contains fused silica hydrophobized with an alkylalkoxysilane coupling agent represented by the following general formula (1), and the number average primary particle size of the fused silica is in the range of 60 to 300 nm. And This feature is a technical feature common to the present invention according to claims 1 to 4.

General formula (1)
R ₁ —Si (OR ₂ ) ₃
(In general formula (1), R ₁ represents an alkyl group which may have a substituent having 6 or more carbon atoms, and R ₂ represents an alkyl group having 1 or 2 carbon atoms.)
Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the present application, “˜” is used in the sense of including the numerical values before and after the lower limit value and the upper limit value.

[Fused silica]
The fused silica according to the present invention is fused silica hydrophobized with the alkylalkoxysilane coupling agent represented by the general formula (1), and the fused silica has a number average primary particle size of 60 to 300 nm. It is characterized by being within the range.

  The fused silica according to the present invention is different from that obtained in a general fused silica production process, and is produced from raw materials via SiO gas, whereby silica particles are obtained as ultrafine powder. is there.

  That is, general fused silica is obtained by pulverizing natural silica raw materials such as silica and flame-melting at a high temperature of about 2000 ° C., while its particle diameter becomes large particles of several μm or more. The fused silica according to the present invention is obtained by heat-treating a mixed raw material composed of finely pulverized silica silica, a reducing agent such as metal silicon powder and carbon powder, and water for forming a slurry at a high temperature in a reducing atmosphere to generate SiO gas. Is characterized in that it is obtained by rapidly cooling it in an atmosphere containing oxygen, and its particle size is submicron or less.

[Method for producing fused silica]
A method for producing fused silica particles according to the present invention will be described.

  Although the kind of raw material silica powder used by this invention is not specifically limited, From the cost surface, the silica powder obtained by grind | pulverizing a silica is preferable. The particle size is preferably from submicron to 100 μm, particularly preferably from 1 to 30 μm, because of the reaction mechanism of the production method of the present invention via SiO gas. If it deviates from this range, it becomes difficult for coarse particles to be gasified to SiO at the heat treatment temperature in the present invention. Further, in the case of fine particles, not only the handleability is deteriorated, but also the particles are aggregated to cause the same obstacle to SiO gasification. The purity is preferably as high as possible.

  In the present invention, there is a great feature in using a mixed raw material in which both a reducing agent composed of metal silicon powder and / or carbon powder and water are mixed with silica powder, and only one of them is sufficient for SiO gasification. In addition, the particle size is not smaller than submicron.

  As in the present invention, when both the reducing agent and water are used, the reason why silica particles having a particle size of submicron or less can be obtained even if the heat treatment is lower than the boiling point of silica is not clear. It is thought that due to the synergistic action of water and water, the bond between Si atoms and O atoms on the surface of the silica particles is first weakened by water vapor, and then the reducing agent acts, resulting in a significant acceleration of gasification to SiO. ing. In addition, the presence of water not only increases the specific surface area but also acts to suppress the residual of the reducing agent.

As the reducing agent used in the present invention, metal silicon powder and / or carbon powder is used. The higher the purity, the better. Among these, metallic silicon is preferable from the viewpoint of promoting the gasification of SiO by reaction heat. The amount of the reducing agent depends on the reaction temperature and cannot be limited, but is generally 0.25 to 1.5 mol with respect to 1 mol of SiO _{2 of the} silica powder raw material.

  The amount of water should not be too great, but it is sufficient that the water content is at least 5% by mass in the mixture of the siliceous raw material powder and the reducing agent. Moreover, you may replace about 30 mass% of water with alcohol, such as ethanol.

  The form of the mixed raw material used in the present invention may be a slurry or a powder. In the case of a slurry, it becomes easy to inject the droplets from the nozzle to the flame, and the productivity can be further improved. As the slurry concentration at that time, the solid content concentration is preferably about 20 to 60% by mass. If it is less than 20% by mass, the productivity is lowered and the amount of heat of evaporation of water is increased, thereby inhibiting gasification to SiO. On the other hand, if it exceeds 60% by mass, it becomes difficult to inject into the flame in the form of droplets, and gasification into SiO is also hindered. As a method for injecting the slurry, a two-fluid nozzle capable of minimizing the droplet diameter as much as possible is preferable, and in particular, a structure having a structure capable of miniaturizing the droplet diameter to several μm is preferable.

  In the present invention, the mixed raw material is subjected to a heat treatment at a high temperature under a reducing atmosphere to generate a SiO-containing gas. The temperature of the heat treatment is preferably 1700 ° C. or higher, particularly preferably 1800 to 2100 ° C. When the heat treatment temperature is extremely low, the gasification reaction to SiO becomes insufficient. Although there is no restriction | limiting in particular in the upper limit of heat processing temperature, When the boiling point (2230 degreeC) of a silica is exceeded, the above-mentioned problem will arise, and 2230 degreeC or less is preferable.

  The high-temperature field of the heat treatment in the present invention can be formed in an electric furnace, a combustion furnace using a flame, etc., but the combustion furnace is used for mass production, easy adjustment of atmosphere, easy provision of local temperature distribution, etc. desirable. As the fuel gas, hydrogen, LPG, natural gas, acetylene gas, propane gas, butane, or the like is used, and as the auxiliary combustion gas, air or oxygen is used.

  In the present invention, the high temperature field of the heat treatment needs to be maintained in a reducing atmosphere in order to promote gasification of the silica powder into SiO. In the case of an electric furnace, it is performed by supplying a reducing gas into a furnace such as hydrogen, hydrocarbon, carbon monoxide or the like, and in the case of a combustion furnace, it is performed by controlling the ratio of the fuel gas to the auxiliary combustion gas. More specifically, the auxiliary combustion gas is supplied in an amount of about 10 to 70% less than the theoretical value. Care should be taken because carbon will remain in the product if it is in an extremely reduced state.

  In the case of using an electric furnace, the supply of the mixed raw material is preferably continuously supplied to a furnace maintained in a high temperature field in the same direction as the flow of the reducing gas or in the opposite direction. In the case of a combustion furnace, it is injected into a flame in a reducing atmosphere. The spraying is performed using a spray atomizer such as a two-fluid nozzle, an ultrasonic atomizer, a rotating disk atomizer, or the like. The two-fluid nozzle is optimal in terms of mass productivity and promotion of gasification to SiO.

  In the case of injection by a two-fluid nozzle, the mixed raw material is desirably supplied as a slurry. In addition, the nozzle structure is preferably one in which droplets formed by slurry spraying are minute and difficult to block. For example, the diameter of the slurry spray tip opening is 2 mm or more, and the nozzle for slurry spray gas at the nozzle tip The gas velocity is preferably 10 m / second or more, particularly preferably 100 to 400 m / second.

  Since the mixed raw material is heat-treated as described above to generate a SiO-containing gas, in the present invention, it is quickly discharged from a high temperature field and cooled in an atmosphere containing oxygen. When the electric furnace is used to discharge the SiO-containing gas, it is mixed with the reducing gas to be exhausted, but can also be actively sucked. In the case of a combustion furnace, it is carried out by positively aspirating as in the case of transporting a melt to a collection system in a normal melting furnace.

  Next, the SiO-containing gas is oxidized in an atmosphere containing oxygen, and SiO becomes silica fine particles and is collected. In either case of an electric furnace or a combustion furnace, this operation is preferably performed by transporting the SiO-containing gas with a gas containing oxygen such as air to a collection system such as a bag filter. In this case, the average particle diameter and specific surface area can be adjusted by the gas introduction position and flow rate. In particular, in the case of using a combustion furnace, the SiO-containing gas that has passed through the flame is still at a high temperature of about 1600 ° C or higher, so a gas containing oxygen is supplied from a portion slightly away from the end of the flame and forced cooling is performed. It is preferable to make it. As described above, the fused silica particles of the present invention can be obtained.

[Hydrophobic treatment]
The fused silica according to the present invention is hydrophobized with an alkylalkoxysilane coupling agent represented by the following general formula (1).

General formula (1)
R ₁ —Si (OR ₂ ) ₃
In the above formula (1), R ₁ is an alkyl group having 6 or more carbon atoms. This is because if the number of carbon atoms is smaller than 6, the hydrophobic effect is reduced. R ₁ is preferably an alkyl group having 20 or less carbon atoms. When it is less than 20, the viscosity of the treatment agent is low, and a uniform surface treatment can be performed.

More preferably, R ₁ has 8 to 16 carbon atoms. R ₂ represents an alkyl group having 1 or 2 carbon atoms, and the alkyl group of R ₂ preferably has 1 carbon atom from the viewpoint of reactivity. The alkyl group for R ₁ may have a substituent, and the substituent for the alkyl group for R ₁ is preferably a hydrophobic group. Among the hydrophobic groups, a halogen atom is more preferable, and a fluorine atom is particularly preferable.

The alkyl group for R _{1 is} an alkyl group having 6 or more carbon atoms which may have a substituent. This alkylalkoxysilane coupling agent having a long-chain alkyl group having 6 or more carbon atoms can improve the hydrophobicity of silica when it is surface-treated and reduce the environmental dependency of the charge amount. it is conceivable that. In addition, hydrophobization with a long alkyl chain alkyl silane coupling agent is considered to exhibit the effect of making it difficult to adsorb moisture to unreacted silanol groups remaining on the silica surface due to the long alkyl chain. It is done.

[Alkylalkoxysilane coupling agent]
Examples of the alkoxysilane compound represented by the above formula (1) include CH ₃ — (CH ₂ ) ₅ —Si (OCH ₃ ) ₃ , CH ₃ — (CH ₂ ) ₅ —Si (OC ₂ H ₅ ) _{3. , CH 3 - (CH 2)} 7 -Si (OCH 3) 3, CH 3 - (CH 2) 7 -Si (OC 2 H 5) 3, CH 3 - (CH 2) 9 -Si (OCH 3) 3 _{, CH 3 - (CH 2)} 9 -Si (OC 2 H 5) 3, CH 3 - (CH 2) 11 -Si (OCH 3) 3, CH 3 - (CH 2) 11 -Si (OC 2 H 5 _{) 3, CH 3 - (CH} 2) 13 -Si (OCH 3) 3, CH 3 - (CH 2) 13 -Si (OC 2 H 5) 3, CH 3 - (CH 2) 15 -Si (OCH 3 ) ₃ , CH ₃ — (CH ₂ ) ₁₅ —Si (OC ₂ H ₅₎ ) ₃ , CH ₃ — (CH ₂ ) ₁₇ —Si (OCH ₃ ) ₃ , CH ₃ — (CH ₂ ) ₁₇ —Si (OC ₂ H ₅ ) ₃ , CH ₃ — (CH ₂ ) ₁₉ —Si (OCH ₃ ) ) ₃ , CH ₃ — (CH ₂ ) ₁₉ —Si (OC ₂ H ₅ ) ₃ , CF ₃ — (CF ₂ ) ₃ —CH ₂ CH ₂ —Si (OC ₂ H ₅ ) ₃ , CF ₃ — (CF _{2) ) 5 -CH 2 CH 2 -Si (} OCH 3) 3, CF 3 - (CF 2) 5 -CH 2 CH 2 -Si (OC 2 H 5) 3, CF 3 - (CF 2) 7 -CH 2 CH _{2 -Si (OCH 3) 3,} CF 3 - (CF 2) 7 -CH 2 CH 2 -Si (OC 2 H 5) 3, CF 3 - (CF 2) 9 -CH 2 CH 2 -Si (OCH 3 ) _3, and _{CF 3 - (CF 2) 9} -CH 2 CH 2 - and the like i _{(OC 2} H _{5) 3,} but satisfy the above equation (1), but is not limited thereto.

Of _{these, CH 3 - (CH 2)} 7 -Si (OCH 3) 3, CH 3 - (CH 2) 9 -Si (OCH 3) 3, CH 3 - (CH 2) 11 -Si (OCH 3) ₃ , CH _3- (CH ₂ ) ₁₃ -Si (OCH ₃ ) ₃ , CH _3- (CH ₂ ) ₁₅ -Si (OCH ₃ ) ₃ , and CF _3- (CF ₂ ) ₇ -CH ₂ CH ₂ -Si (OCH ₃ ) ₃ is preferred.

  The hydrophobizing treatment can be performed by a commonly performed method, and for example, a dry method or a wet method can be used.

  The dry method is performed by stirring or mixing the silica powder and the alkylalkoxysilane represented by the general formula (1) in a fluidized bed reactor.

  In the wet method, silica powder is dispersed in a solvent to form a slurry of silica particles, and then the alkylalkoxysilane represented by the general formula (1) is added to the slurry, and the surface of the silica particles is alkylalkoxylated. Modified with silane.

  Furthermore, it can also be hydrophobized using a batch or continuous process in which the dry silica powder is in contact with a liquid or vapor alkylalkoxysilane with thorough mixing.

  The mixture of silica particles and alkylalkoxysilane can be effectively modified with alkylalkoxysilane on the silica particle surface by heating for 0.5 to 5 hours in the range of 100 to 200 ° C. .

  In addition, as a quantity of the said alkyl alkoxysilane which is a surface treating agent, the range of 5-30 mass parts is preferable with respect to 100 mass parts of silica particles, and the range of 8-20 mass parts is more preferable.

[Number average primary particle diameter of fused silica]
In the present invention, the number average primary particle diameter of the fused silica particles is in the range of 60 to 300 nm.

  By making the number average primary particle diameter of the fused silica particles in the range of 60 to 300 nm, the cleaning property is excellent, and the fluidity is secured, so that the rising of the charge is also good. This is because if the thickness is smaller than 60 nm, poor cleaning tends to occur, and if it is larger than 300 nm, the fluidity may not be sufficiently secured. Further, the number average primary particle diameter of the fused silica particles is more preferably in the range of 80 to 150 nm from the viewpoint that the cleaning property and fluidity can be maintained throughout the durable life.

[Measurement method of number average primary particle size]
The number average primary particle diameter of the silica particles is measured by an image analysis method. Specifically, using a scanning electron microscope, a photograph of the toner is taken at a magnification of 3 to 50,000 times, and the photograph image is captured by a scanner, and the image processing analysis apparatus “LUXEX AP (manufactured by Nireco)” is used. The silica particles present on the surface of the toner particles on the photographic image are binarized, the horizontal ferret diameter is calculated for 100 arbitrary silica particles, and the average value is taken as the number average primary particle diameter. Here, the horizontal ferret diameter refers to the length of a side parallel to the x-axis of the circumscribed rectangle when the image of the external additive is binarized.

  When the number average primary particle diameter of the external additive is small and exists as an aggregate on the toner surface, the number average primary particle diameter of the primary particles forming the aggregate is measured.

[Average sphericity of silica]
Moreover, it is preferable that the average sphericity of a fused silica exists in the range of 0.9-1.0. It is preferable that the average sphericity is in the above-mentioned range since fluidity can be ensured and the rising of charging becomes good.

[Measurement method of average sphericity]
The average sphericity was measured by image analysis of a particle image photographed at a magnification of 50,000 with a scanning electron microscope “FE-SEM model JSM-6301F” manufactured by JEOL. That is, the projected area (A) and the perimeter (PM) of the particle are measured from the photograph. When the area of a perfect circle corresponding to the perimeter (PM) is (B), the roundness of the particle is expressed as A / B. Therefore, assuming a perfect circle having the same circumference as the circumference of the sample particle (PM), it is represented by PM = 2πr and B = πr ² , so that B = π × (PM / 2π) ² . The sphericity of the particles can be calculated as sphericity = A / B = A × 4π / (PM) ² . Thus, the sphericity of arbitrary 200 silica particles was determined, and the average value was defined as the average sphericity of silica.

[Moisture content of fused silica]
When the fused silica according to the present invention has a moisture content of less than 3% by mass when left in an environment of 30 ° C. and 80% RH for 48 hours, a toner having excellent environmental stability of charging characteristics can be obtained. Therefore, it is preferable. Furthermore, it is more preferable that it is less than 1.5 mass%. The fused silica according to the present invention is prepared by subjecting the fused silica produced as described above to a hydrophobic treatment with an alkylalkoxysilane coupling agent represented by the general formula (1), thereby providing an environment of 30 ° C. and 80% RH. The moisture content when allowed to stand below for 48 hours can be less than 3% by mass.

[Measurement of moisture content]
The measurement of the moisture content of fused silica is performed as follows. That is, it is performed by the Karl Fischer coulometric titration method. Specifically, using an automatic heat-vaporization moisture measurement system (AQS-724, Hiranuma Sangyo Co., Ltd.), the fused silica left for 48 hours in a 30 ° C / 80% RH environment is accurately weighed into a 20 ml glass sample tube. And then sealed with a Teflon-coated silicone rubber packing. In order to correct the moisture present in the sealed environment, two empty samples are measured simultaneously. The measurement is performed for 1 minute under the conditions of heating temperature = 110 ° C./carrier gas (nitrogen) flow rate = 150 ml / min. Hydranal Aqualite RS (manufactured by Riedel de Haen) and Aqualite C (manufactured by Kanto Chemical Co., Inc.) are used as reagents.

[Other external additives]
In the present invention, other known external additives can be added to the extent that the characteristics of the fused silica according to the present invention are not impaired. These external additives are not particularly limited, and various inorganic fine particles, organic fine particles and lubricants can be used.

  As the inorganic fine particles, it is preferable to use inorganic oxide particles such as silica, titania, or alumina, and these inorganic fine particles are preferably hydrophobized with a silane coupling agent or a titanium coupling agent. . As the organic fine particles, spherical particles having a number average primary particle diameter of about 10 to 2000 nm can be used.

  As the organic fine particles, polymers such as polystyrene, polymethyl methacrylate, and styrene-methyl methacrylate copolymer can be used.

  The total amount of external additives added is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, with respect to 100 parts by mass of toner base particles.

[Toner base particles]
As the toner base particles constituting the toner for developing an electrostatic charge image (hereinafter also simply referred to as “toner”) of the present invention, known toner base particles can be used. Such toner base particles are specifically composed of toner base particles containing at least a resin (hereinafter also referred to as “toner resin”) and, if necessary, a colorant. Further, the toner base particles may further contain other components such as a release agent and a charge control agent, if necessary.

[Toner resin]
As the binder resin constituting the toner, it is preferable to use a thermoplastic resin.

  As such a binder resin, those generally used as a binder resin constituting a toner can be used without particular limitation. Specifically, for example, styrene resins, alkyl acrylates, alkyl methacrylates, and the like can be used. Examples thereof include acrylic resins, styrene acrylic copolymer resins, polyester resins, silicone resins, olefin resins, amide resins, and epoxy resins.

  Among these, a styrene resin, an acrylic resin, a styrene acrylic copolymer resin, and a polyester resin, which have low melt viscosity and high sharp melt properties, are preferable. It is preferable to use 50% or more of a styrene acrylic copolymer resin as the main resin. These can be used alone or in combination of two or more.

  Examples of the polymerizable monomer for obtaining the binder resin include styrene monomers such as styrene, methylstyrene, methoxystyrene, butylstyrene, phenylstyrene, chlorostyrene; methyl (meth) acrylate, ethyl ( (Meth) acrylate ester monomers such as (meth) acrylate, butyl (meth) acrylate and ethylhexyl (meth) acrylate; use of carboxylic acid monomers such as acrylic acid, methacrylic acid and fumaric acid Can do.

  These can be used alone or in combination of two or more.

  The binder resin constituting the toner preferably has a glass transition temperature (Tg) of 30 to 50 ° C. from the viewpoint of low-temperature fixing. When the glass transition temperature is within this range, the low-temperature fixing property and the heat-resistant storage property are good.

  The measurement of the glass transition temperature of the binder resin can be performed using “Diamond DSC” (manufactured by Perkin Elmer).

  As a measurement procedure, 3.0 mg of toner is sealed in an aluminum pan and set in a holder. The reference uses an empty aluminum pan. The measurement conditions were a measurement temperature of 0 to 200 ° C., a temperature increase rate of 10 ° C./min, a temperature decrease rate of 10 ° C./min, and heat-cool-heat temperature control. Analysis is performed based on the data in Heat.

  The glass transition temperature draws an extension of the baseline before the rise of the first endothermic peak and a tangent line indicating the maximum slope between the rise of the first peak and the peak apex, and the intersection is taken as the glass transition point. Show.

  Furthermore, the softening point temperature of the binder resin is preferably 80 to 130 ° C, more preferably 90 to 120 ° C.

[Colorant]
As the colorant constituting the toner, a known inorganic or organic colorant can be used.

  The addition amount of the colorant is in the range of 1 to 30% by mass, preferably 2 to 20% by mass with respect to the whole toner.

〔Release agent〕
The toner may contain a release agent. Here, the release agent is not particularly limited. For example, hydrocarbon waxes such as polyethylene wax, oxidized polyethylene wax, polypropylene wax, oxidized polypropylene wax, carnauba wax, fatty acid ester wax, sacrificial wax. Examples thereof include sol wax, rice wax, candelilla wax, jojoba oil wax, and beeswax wax.

  The content ratio of the release agent in the toner base particles is usually 1 to 30 parts by weight, and more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the toner base particle forming binder resin. The

[Charge control agent]
The toner may contain a charge control agent. For example, metal complexes (salicylic acid metal complexes) of salicylic acid derivatives such as zinc and aluminum, calixarene compounds, organic boron compounds, and fluorine-containing quaternary ammonium salt compounds can be used.

  The content ratio of the charge control agent in the toner base particles is usually in the range of 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the binder resin.

[Method for producing toner base particles]
The toner of the present invention is obtained by adding an external additive to toner base particles. The toner base particles can be produced by a kneading pulverization method, a suspension polymerization method, an emulsion aggregation method, a dissolution suspension. Method, polyester elongation method, and dispersion polymerization method.

  Among these, it is preferable to employ the emulsion aggregation method from the viewpoints of particle size uniformity, shape controllability, and ease of core-shell structure formation, which are advantageous for high image quality and high stability.

  In the emulsion aggregation method, a dispersion of resin fine particles dispersed with a surfactant or a dispersion stabilizer is mixed with a dispersion of toner base particle constituents such as colorant fine particles, if necessary, and a flocculant is added. In this method, toner base particles are produced by agglomerating until the desired toner particle diameter is obtained, and thereafter or simultaneously with the aggregation, fusion between resin fine particles is performed, and shape control is performed.

  Here, the resin fine particles may optionally contain internal additives such as a release agent and a charge control agent, and are formed of a plurality of layers composed of two or more layers made of resins having different compositions. It can also be.

  In addition, it is also preferable from the viewpoint of toner structure design to add different types of resin fine particles during aggregation to form toner base particles having a core-shell structure.

  The resin fine particles can be produced, for example, by an emulsion polymerization method, a miniemulsion polymerization method, a phase inversion emulsification method, or the like, or can be produced by combining several production methods. When an internal additive is contained in the resin fine particles, it is preferable to use a miniemulsion polymerization method.

(External additive addition method)
The external additive adding step is a step of preparing toner particles by adding and mixing external additives as necessary to the dried toner base particles.

  The toner base particles prepared through the steps up to the drying step can be used as toner particles as they are, but are known on the surface from the viewpoint of improving charging performance, fluidity, or cleaning properties as a toner. Particles such as inorganic fine particles and organic fine particles, and a lubricant are added as external additives.

  Examples of the method of adding the external additive include a dry method in which the external additive is added in powder form to the dried toner base particles. Examples of the mixing device include mechanical mixing devices such as a Henschel mixer and a coffee mill. It is done.

[Particle size of toner particles]
The toner particles according to the present invention preferably have a volume-based median diameter (D ₅₀ ) of 3 to 8 μm.

The volume-based median diameter (D ₅₀ ) of the toner particles is a measuring device in which a computer system equipped with data processing software “Software V3.51” is connected to “Coulter Multisizer 3” (manufactured by Beckman Coulter). Is to be measured.

Specifically, 0.02 g of toner is added to 20 ml of a surfactant solution (for example, a surfactant solution in which a neutral detergent containing a surfactant component is diluted 10 times with pure water for the purpose of dispersing the toner). Then, ultrasonic dispersion was performed for 1 minute to prepare a toner dispersion, and this toner dispersion was placed in a beaker containing “ISOTON II” (manufactured by Beckman Coulter) in a sample stand. Pipette until the indicated concentration is 8%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measurement apparatus, the measurement particle count is 25000, the aperture diameter is 50 μm, the frequency value is calculated by dividing the measurement range of 1 to 30 μm into 256, and the volume integrated fraction is 50 % Particle diameter is defined as the volume-based median diameter (D ₅₀ ).

(Developer)
The toner of the present invention can be used as a magnetic or nonmagnetic one-component developer, but may be mixed with a carrier and used as a two-component developer. When this toner is used as a two-component developer, the carrier may be a magnetic material made of a conventionally known material such as a metal such as iron, ferrite, or magnetite, or an alloy of such a metal with a metal such as aluminum or lead. Particles can be used, and ferrite particles are particularly preferable. Further, as the carrier, a coat carrier in which the surface of the magnetic particles is coated with a coating agent such as a resin, a binder type carrier in which a magnetic fine powder is dispersed in a binder resin, or the like may be used.

  The coating resin constituting the coat carrier is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene-acrylic resins, acrylic resins, silicone resins, ester resins, and fluorine resins. Moreover, it does not specifically limit as binder resin which comprises a binder type carrier, A well-known thing can be used, For example, a styrene-acrylic-type resin, a polyester resin, a fluororesin, a phenol resin etc. can be used. . Among these, a coat carrier coated with a styrene-acrylic resin or an acrylic resin is preferable from the viewpoint of chargeability and durability.

  The carrier preferably has a volume average particle size of 20 to 100 μm, more preferably 25 to 80 μm, since a high-quality image can be obtained and carrier fog is suppressed. The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS (manufactured by SYMPATEC)” equipped with a wet disperser.

[Electrophotographic image forming method]
The toner according to the present invention can be suitably used in an electrophotographic image forming method including a fixing step by a contact heating method. Specifically, as the image forming method, an electrostatic latent image electrostatically formed on, for example, an electrostatic latent image carrier (also referred to as a photoreceptor) using the above-described toner is developed into a developing device. The toner is made visible by charging the developer with a frictional charging member in FIG. Then, this toner image is transferred onto a sheet, and then the toner image transferred onto the sheet is fixed on the sheet by a contact heating type fixing process, thereby obtaining a visible image.

[Electrophotographic image forming apparatus]
The toner of the present invention can be used in a general electrophotographic image forming apparatus. As an image forming apparatus in which such an image forming method is performed, for example, a photosensitive member that is an electrostatic latent image carrier, A charging means for applying a uniform potential to the surface of the photoconductor by corona discharge having the same polarity as that of the toner, and an electrostatic latent image by performing image exposure on the surface of the uniformly charged photoconductor based on image data. An exposure means for forming an image; a developing means for conveying the toner to the surface of the photoreceptor to visualize the electrostatic latent image to form a toner image; and passing the toner image through an intermediate transfer member as necessary. For example, a transfer unit that transfers to a transfer material and a fixing unit that fixes a toner image on the transfer material can be used. Among image forming apparatuses having such a configuration, a color image forming apparatus having a configuration in which image forming units related to a plurality of photoconductors are provided along the intermediate transfer body, in particular, the photoconductors are arranged in series on the intermediate transfer body. It can be suitably used for the tandem type color image forming apparatus.

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

[1. Toner Production Example 1]
(1) Production Step of Core Part Resin Fine Particles [1] Core part resin fine particles [1] having a multilayer structure were produced through the first stage polymerization, second stage polymerization and third stage polymerization shown below.

(A) First stage polymerization (resin fine particles [A1])
A surfactant solution prepared by dissolving 4 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate in 3040 parts by mass of ion-exchanged water in a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction apparatus. The internal temperature was raised to 80 ° C. while stirring and stirring at a stirring speed of 230 rpm under a nitrogen stream. To this surfactant solution, a polymerization initiator solution in which 10 parts by mass of a polymerization initiator (potassium persulfate: KPS) was dissolved in 400 parts by mass of ion-exchanged water was added to a temperature of 75 ° C., and then 532 masses of styrene. A monomer mixture consisting of 1 part by weight, 200 parts by weight of n-butyl acrylate, 68 parts by weight of methacrylic acid, and 16.4 parts by weight of n-octyl mercaptan was dropped over 1 hour, and this system was kept at 75 ° C. for 2 hours. Polymerization (first stage polymerization) was carried out by heating and stirring to produce resin fine particles [A1]. The mass average molecular weight (Mw) of the resin fine particles [A1] produced by the first stage polymerization was 16,500.

The mass average molecular weight (Mw) was measured using “HLC-8220” (manufactured by Tosoh Corporation) and the column “TSKguardcolumn + TSKgelSuperHZM-M3 series” (manufactured by Tosoh Corporation) while maintaining the column temperature at 40 ° C. and tetrahydrofuran as a carrier solvent. (THF) was allowed to flow at a flow rate of 0.2 ml / min, and the measurement sample was dissolved in tetrahydrofuran to a concentration of 1 mg / ml under a dissolution condition in which treatment was performed for 5 minutes using an ultrasonic disperser at room temperature. A sample solution is obtained by treatment with a 2 μm membrane filter, and 10 μl of this sample solution is injected into the apparatus together with the carrier solvent described above, detected using a refractive index detector (RI detector), and the molecular weight of the measurement sample Using a calibration curve whose distribution was measured using monodisperse polystyrene standard particles To calculate. As a standard polystyrene sample for calibration curve measurement, the molecular weights manufactured by Pressure Chemical are 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1 .1 × 10 ⁵ , 3.9 × 10 ⁶ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ , and at least about 10 standard polystyrene samples were measured, and a calibration curve It was created. A refractive index detector was used as the detector.

(B) Second stage polymerization (resin fine particles [A2]: formation of intermediate layer)
In a flask equipped with a stirrer, a monomer mixture comprising 101.1 parts by mass of styrene, 62.2 parts by mass of n-butyl acrylate, 12.3 parts by mass of methacrylic acid, and 1.75 parts by mass of n-octyl mercaptan In addition, 93.8 parts by mass of paraffin wax “HNP-57” (manufactured by Nippon Seiki Co., Ltd.) was added as a release agent, and the mixture was heated to 90 ° C. and dissolved.

  On the other hand, a surfactant solution in which 3 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate was dissolved in 1560 parts by mass of ion-exchanged water was heated to 98 ° C., and the resin fine particles [A1 ] 32.8 parts by mass (in terms of solid content) was added, and the monomer solution containing the paraffin wax was mixed and dispersed for 8 hours using a mechanical disperser “CLEAMIX” (manufactured by M Technique Co., Ltd.) having a circulation path. And a dispersion containing emulsified particles having a dispersed particle diameter of 340 nm was prepared. Next, a polymerization initiator solution in which 6 parts by mass of potassium persulfate was dissolved in 200 parts by mass of ion-exchanged water was added to this emulsified particle dispersion, and the system was polymerized by heating and stirring at 98 ° C. for 12 hours. (Second-stage polymerization) was performed to produce resin particles [A2]. The Mw of the resin fine particles [A2] prepared by the second stage polymerization was 23,000.

(C) Third-stage polymerization (core resin fine particles [1]: formation of outer layer)
A polymerization initiator solution in which 5.45 parts by mass of potassium persulfate was dissolved in 220 parts by mass of ion-exchanged water was added to the resin fine particles [A2], and 293.8 parts by mass of styrene under a temperature condition of 80 ° C., A monomer mixed solution consisting of 154.1 parts by mass of n-butyl acrylate and 7.08 parts by mass of n-octyl mercaptan was added dropwise over 1 hour. After completion of dropping, the mixture was heated and stirred for 2 hours to perform polymerization (third stage polymerization), and then cooled to 28 ° C. to obtain core part resin particles [1]. In addition, Mw of the resin particle for core part [1] was 26,800. The volume average particle diameter of the core part resin particles [1] was 125 nm. Furthermore, the glass transition temperature (Tg) of the resin fine particles for core part [1] was 28.1 ° C.

(2) Production process of resin fine particles for shell layer [1] In the first stage polymerization of the resin fine particles for core part [1], 548 parts by mass of styrene, 156 parts by mass of 2-ethylhexyl acrylate, and 96 of methacrylic acid. Resin fine particles for shell layer [1] are produced in the same manner except that a monomer mixed solution in which n-octyl mercaptan is changed to 16.5 parts by mass is used. did. The Tg of the resin fine particles for shell layer [1] was 53.0 ° C.

(3) Preparation of Colorant Fine Particle Dispersion [1] 90 parts by mass of sodium dodecyl sulfate was added to 1600 parts by mass of ion-exchanged water, and while stirring this solution, carbon black “Regal 330R” (manufactured by Cabot Corporation) 420 parts by mass The colorant fine particle dispersion liquid [1] in which the colorant fine particles are dispersed was prepared by performing a dispersion treatment using a stirrer “Clearmix” (manufactured by M Technique Co., Ltd.). .

  The particle diameter of the colorant fine particles in this colorant fine particle dispersion [1] was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.) and found to be 110 nm.

(4) Preparation of toner base particle [1] (a) Formation of core part [1] 420 parts by mass of fine resin fine particles for core part [1] (in terms of solid content), 900 parts by mass of ion-exchanged water, and coloring 100 parts by mass of the agent fine particle dispersion [1] was placed in a reaction vessel equipped with a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device and stirred. After adjusting the temperature in the reaction vessel to 30 ° C., 5 mol / liter sodium hydroxide aqueous solution was added to this solution to adjust the pH to 8-11.

Next, an aqueous solution obtained by dissolving 60 parts by mass of magnesium chloride hexahydrate in 60 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, the heating was started, and the system was heated to 80 ° C. (core formation temperature) over 80 minutes. In this state, the particle diameter of the particles was measured with “Coulter Multisizer 3” (manufactured by Coulter Inc.). When the median diameter (D ₅₀ ) on the volume basis of the particles became 5.8 μm, sodium chloride 40.2 Add an aqueous solution in which parts by mass are dissolved in 1000 parts by mass of ion-exchanged water to stop particle size growth,
Furthermore, as the aging treatment, the fusion was continued by heating and stirring at a liquid temperature of 80 ° C. (core aging temperature) for 1 hour to form the core part [1]. The circularity of the core [1] was 0.930 as measured by “FPIA2100” (manufactured by Sysmex Corporation). In addition, using a field emission scanning electron microscope JSM-7401F (manufactured by JEOL Ltd.), the core part [1] was observed at a magnification of 10,000 by scanning transmission electron microscopy, and the colorant was dissolved in the binder resin. It was confirmed that no colorant-dispersed fine particles remained.

(B) Formation of Shell Layer Next, 46.8 parts by mass of resin fine particles for shell layer [1] (in terms of solid content) are added at 65 ° C., and further 2 parts by mass of magnesium chloride hexahydrate is added to ion-exchanged water 60 An aqueous solution dissolved in parts by mass was added over 10 minutes, and then the temperature was raised to 80 ° C. (shell formation temperature), and stirring was continued for 1 hour. Resin fine particles for the shell layer were formed on the surface of the core part [1]. After fusing the particles of [1], aging treatment was performed at 80 ° C. (shell aging temperature) to a predetermined circularity to form a shell layer. Here, an aqueous solution in which 40.2 parts by mass of sodium chloride was dissolved in 1000 parts by mass of ion-exchanged water was added, and the mixture was cooled to 30 ° C. at 8 ° C./min. The toner base material having a shell layer on the surface of the core part and having a shell layer on the surface of the core part and having a median diameter (D ₅₀ ) of 5.9 μm and Tg of 31 ° C. by repeatedly washing with exchange water and then drying with hot air of 40 ° C. Particles [1] were obtained.

(5) Method for producing fused silica external additive (5-1) Silica particle production apparatus Ultrafine silica was produced using a combustion furnace. The combustion furnace is provided with a double-pipe LPG-oxygen mixed burner at the top of the furnace so that an inner flame and an outer flame can be formed, and a two-fluid nozzle for slurry injection at the center of the burner. Is attached. Then, slurry is injected into the flame from the center of the two-fluid nozzle and oxygen is injected from the periphery thereof. The formation of the flame is performed by injecting a mixed gas of LPG-oxygen for forming the outer flame and the inner flame from the pores of the respective injection ports of the double tube structure burner, and the amount of LPG and oxygen gas These temperatures and atmospheres are adjusted by controlling. The part where the flame is formed is a reaction part, and contact with the air layer is cut off by the formation of the flame. Further, the side wall of the reaction part is protected by an alumina heat insulating material, and an air introduction hole is provided near the end of the reaction part, so that the generated gas can be rapidly oxidized. The product is sent to a collection system by a blower and collected by a bug filter.

100 mass of mixed powder consisting of 1.0 mol of metal silicon powder (number average particle size 10 μm, maximum particle size 100 μm) with respect to 1.0 mol of SiO _{2 of} silica powder (number average particle size 2 μm, maximum particle size 60 μm) A portion having a slurry concentration of 50% was prepared. This was injected from the center of a two-fluid nozzle (“Model No. BNH160S-IS” manufactured by Atmax Co., Ltd.) into the flame of the combustion furnace at a rate of 20 kg / h. For injection, oxygen gas having a gauge pressure of 0.3 MPa and a gas amount of about 12 Nm ³ / h was used.

On the other hand, from the burner, for the internal flame, a mixed gas of LPG: 6 Nm ³ / h and oxygen gas: 12 Nm ³ / h (corresponding to 40% of the complete combustion amount) is covered with the reducing flame and the injection portion of the slurry is covered with the reducing flame Injecting a mixture gas of LPG: 4 Nm ³ / h and oxygen gas: 16 Nm ³ / h (equivalent to 80% of the complete combustion amount) from the outermost peripheral space of the burner for external flame Shut off inner flame and external air layer. Moreover, the air supply amount from the air introduction hole is appropriately adjusted within a range of 50 to 200 Nm ³ / h. The temperature of the inner flame part covering the injection part was measured at the center of the flame using a W-Re thermocouple. Furthermore, the determination of the reducibility of the internal flame part was judged by the oxygen concentration, and it was confirmed that the oxygen concentration was always 1% by mass or less.

(5-2) Manufacture of fused silica external additive (a) Manufacture of fused silica base particles In the above manufacturing conditions, the fused silica base particles [1] by combining the internal flame temperature and the amount of cooling air as shown in Table 1 To [7] were produced.

（ｂ）疎水化処理
上記溶融シリカ母体粒子〔１〕１００質量部を反応容器に入れ、窒素雰囲気下、攪拌しながら、水２．５ｇを噴霧した。これに、疎水化処理剤デシルトリメトキシシラン１５質量部、ジエチルアミン１．０質量部を噴霧し、１８０℃で１時間過熱攪拌し、その後冷却し、疎水性の溶融シリカ外添剤（Ａ−１）を得た。

(B) Hydrophobization treatment 100 parts by mass of the fused silica base particles [1] were put in a reaction vessel, and 2.5 g of water was sprayed with stirring in a nitrogen atmosphere. To this, 15 parts by mass of a hydrophobizing agent decyltrimethoxysilane and 1.0 part by mass of diethylamine are sprayed, stirred at 180 ° C. for 1 hour, then cooled, and then a hydrophobic fused silica external additive (A-1 )

  By combining the fused silica base particles shown in Table 1 and the hydrophobizing agent shown in Table 2, the fused silica external additives (A-1) to (A-15) shown in Table 3 in the above production method Was made.

（５−３）ゾルゲルシリカ外添剤の製造方法
（ａ）ゾルゲルシリカ粒子の製造
攪拌機、滴下ロート、温度計をガラス製反応器にセットし、エタノールに、アンモニア水を加え攪拌し、２０℃に保った。次にこの溶液にテトラエトキシシランを６０分間で滴下し反応させた。滴下終了後さらに２０℃にて５時間攪拌を続けシリカゾル懸濁液を得た。つぎにこのシリカゾル懸濁液を加熱し、エタノールを除去した後トルエンを加え更に加熱し、水を除去した。

(5-3) Method for producing sol-gel silica external additive (a) Production of sol-gel silica particles A stirrer, a dropping funnel and a thermometer are set in a glass reactor, and ammonia water is added to ethanol and stirred, and the mixture is heated to 20 ° C. Kept. Next, tetraethoxysilane was dropped into the solution for 60 minutes to react. After completion of the dropwise addition, the mixture was further stirred at 20 ° C. for 5 hours to obtain a silica sol suspension. Next, this silica sol suspension was heated to remove ethanol, and then toluene was added and further heated to remove water.

(B) Hydrophobizing treatment Next, 15 parts by mass of the hydrophobizing agent decyltrimethoxysilane was added to the silica particles in the suspension, followed by reaction at 120 ° C. for 2 hours to hydrophobize the silica. Thereafter, the suspension was heated to remove toluene and dried to obtain a sol-gel silica external additive (B-1) having a number average primary particle size of 120 nm.

(Measurement of number average primary particle diameter of silica external additive)
The number average primary particle size was measured as follows. The silica particles produced as described above were photographed with a scanning electron microscope at a magnification of 50,000 times using a toner produced by mixing with toner base particles [1] as described later, This photographic image is captured by a scanner, and the silica particles existing on the toner particle surface on the photographic image are binarized by an image processing analyzer “LUXEX AP (manufactured by Nireco)”, and any 100 of the silica particles are processed. The horizontal ferret diameter was calculated and the average value was taken as the number average primary particle diameter.

  In combination with the sol-gel silica particles and the hexamethyldisilazane hydrophobizing agent in the method for producing the sol-gel silica external additive (B-1), the sol-gel silica external additive (B- 2) was produced.

  As shown in Table 3, the obtained silica external additives (A-1) to (A-15) and (B-1) and (B-2) are number average primary particles according to the above-described method. Diameter, moisture content, and average sphericity were measured.

（６）外添剤の添加：トナー１の作製
乾燥されたトナー母体粒子〔１〕に、上記表３記載の溶融シリカ外添剤（Ａ−１）を２．５質量％、小径シリカ外添剤ＲＸ−２００（フュームドシリカ ヘキサメチルジシラザン処理 １２ｎｍ 日本アエロジル社製）を０．６質量％添加し、ヘンシェルミキサー「ＦＭ１０Ｂ」（三井三池化工機社製）を用いて撹拌羽根周速を４０ｍ／秒、処理温度３０℃で１５分間混合し、その後、目開き９０μｍの篩いを用いて粗大粒子を除去することにより、トナー１を作製した。

(6) Addition of external additive: preparation of toner 1 2.5% by mass of the fused silica external additive (A-1) shown in Table 3 above and small-diameter silica external addition to the dried toner base particles [1]. Agent RX-200 (fumed silica hexamethyldisilazane treatment 12 nm, manufactured by Nippon Aerosil Co., Ltd.) was added in an amount of 0.6% by mass, and the stirring blade peripheral speed was adjusted to 40 m using a Henschel mixer “FM10B” (Mitsui Miike Chemical Co., Ltd.). The toner 1 was produced by mixing for 15 minutes at a processing temperature of 30 ° C./second, and then removing coarse particles using a sieve having an opening of 90 μm.

[2. Toner Production Examples 2 to 18]
In Toner Production Example 1, Toner 2 was similarly prepared except that the fused silica external additive (A-1) and the small-diameter silica external additive added in the external additive addition step were changed to the combinations shown in Table 4. ~ 18 were obtained.

〔３．現像剤の製造例１〜１８〕
トナー１〜１８の各々に対して、シリコーン樹脂を被覆した体積基準のメディアン径が３５μｍのフェライトキャリア１を、トナー濃度が７．５質量％となるよう混合することにより、現像剤１〜１８を作製した。

[3. Developer Production Examples 1-18]
Each of the toners 1 to 18 is mixed with a ferrite carrier 1 having a volume-based median diameter of 35 μm coated with a silicone resin so that the toner concentration becomes 7.5% by mass. Produced.

<Evaluation>
Table 5 shows the results of determination on the following evaluation items.

[1. (Charge rise)
Developers 1-18 are each placed in a 20 ml glass container, shaken 200 times a minute, with a swing angle of 45 degrees, with an arm of 50 cm for 1 minute and 20 minutes in an environment of 25 ° C. and 40% RH, and then blow-off method The amount of charge was measured with

  The rank was evaluated as follows according to the ratio of “charge amount after shaking for 1 minute / charge amount after shaking for 20 minutes”.

A: 0.9 or more (excellent)
○: 0.8 to less than 0.9 (good)
Δ: 0.6 to less than 0.8 (practical)
×: Less than 0.6 (not practical)
In a color image forming apparatus “bizhub PRO C6500” (manufactured by Konica Minolta Business Technologies), developers 1 to 18 are sequentially loaded, and an image with a pixel rate of 5% is placed on A4 size fine paper (64 g / m ² ). 1000 sheets were output.
The test was carried out in a low temperature and low humidity environment (LL) having a temperature of 10 ° C. and a relative humidity of 10% and in a high temperature and high humidity environment (HH) having a temperature of 30 ° C. and a relative humidity of 80%.

[2. (Environmental stability of charge amount)
In the actual image evaluation, the charge amount was measured as follows, and the environmental stability of the charge amount was measured.

  In a low temperature and low humidity environment (LL) and a high temperature and high humidity environment (HH), the developer on the mag roll after outputting 1,000 sheets is collected and the amount of charge is measured. The rank was evaluated as follows by the difference between the amount and the charge amount under high temperature and high humidity (HH).

A: Less than 2 μC / g (excellent)
○: 2 μC / g to less than 8 μC / g (good)
Δ: 8 μC / g to less than 12 μC / g (practical)
×: 12 μC / g or more (not practical)
[3. (Cleanability)
The ranks of the remaining cleaning wipes on the photosensitive member after outputting 1000 sheets of 5% original under high temperature and high humidity (HH) were evaluated as follows.

表５に示したように、溶融シリカを用いた本発明のトナー１〜１２は帯電立ち上がり性、帯電量の環境安定性及びクリーニング性において優れた性能を発揮するものであるのに対して、比較用のトナー１３〜１８は、帯電立ち上がり性、帯電量の環境安定性、クリーニング性のいずれかの特性において劣っていることが分かる。 ◎: No wiping left (excellent)
○: Almost no wiping left (good)
Δ: Slightly left unwiped (not generated on image) (practical)
×: Wipe left (image noise generated) (not practical)

As shown in Table 5, the toners 1 to 12 of the present invention using fused silica exhibit excellent performance in charge rising property, environmental stability of charge amount and cleaning property, whereas It can be seen that the toners 13 to 18 for use are inferior in any of the characteristics of charge rising property, environmental stability of charge amount, and cleaning property.

Claims (4)

An electrostatic charge image developing toner comprising toner base particles containing at least a binder resin and an external additive, wherein the external additive is at least an alkyl represented by the following general formula (1) A toner for developing electrostatic images, comprising fused silica hydrophobized with an alkoxysilane coupling agent, wherein the fused silica has a number average primary particle size in the range of 60 to 300 nm.
General formula (1)
R ₁ —Si (OR ₂ ) ₃
(In general formula (1), R ₁ represents an alkyl group which may have a substituent having 6 or more carbon atoms, and R ₂ represents an alkyl group having 1 or 2 carbon atoms.)   2. The electrostatic image development according to claim 1, wherein the fused silica has a water content of less than 3% by mass when the fused silica is left for 48 hours in an environment of 30 ° C. and 80% RH. toner.   3. The electrostatic image developing toner according to claim 1, wherein the fused silica has an average sphericity of 0.9 to 1.0.   An electrophotographic image forming method for forming an image through at least each process of charging, exposure, development, transfer, and fixing, wherein the development process includes any one of claims 1 to 3. An electrophotographic image forming method comprising using the toner for developing an electrostatic charge image described above.