JP3714916B2 - Toner for developing electrostatic latent image and image forming method using the same - Google Patents

Description

＊比較例３の評価において、連続印刷５万枚で感光体に現像剤が顕著に付着し、安定した画質が得られなくなったため、評価を中止した。
＊実施例４の評価において、約5000枚後にトナー薄層が乱れ、安定した画質が得られなくなったため、評価を中止した。
【００６２】
【発明の効果】
本発明の静電潜像現像用トナーおよびそれを用いた画像形成方法によれば、バインダー樹脂および磁性粉を含むトナー粒子に対して、疎水化度が異なる第１の疎水性無機金属研磨剤としての酸化チタンと、第２の疎水性無機金属研磨剤としての酸化チタンと、を外添処理することにより、高温高湿条件および低温低湿条件のいずれの環境条件においても、帯電特性が安定するとともに、感光体に対する優れた研磨効果を発揮することができるようになり、また、均一な薄層を形成することができるようになった。したがって、均一な帯電特性やチャージアップ防止性をいずれの環境条件下でも発揮することができ、結果として、高画質の画像が長期間にわたって安定して得られるようになった。
【００６３】
【図面の簡単な説明】
【図１】 プリンターの内部構造や動作を説明するために供する図である。
【００６４】
【符号の説明】
１：画像形成装置
２：ポリゴンミラー
５：光学電送機構
７：上部扉
９：感光体
１０：現像器
３１：トナーコンテナ
３２：現像ローラ
３３：供給ローラ
３９：トナーセンサ
４７：表示部[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a toner for developing an electrostatic latent image containing external additive particles and an image forming method using the same, and more specifically, excellent in high temperature and high humidity conditions and low temperature and low humidity conditions, that is, in all environments. The present invention relates to an electrostatic latent image developing toner having charging characteristics and charge-up prevention properties, and an image forming method using the same.
[0002]
[Prior art]
  In electrophotography, the toner used to make an electrostatic latent image a visible image is generally premixed with thermoplastic resin (binder resin), waxes, charge control agent, magnetic powder, and other additives. After that, the toner is manufactured as a toner having a desired particle diameter through each of the manufacturing steps of the melt kneading step, the pulverizing step, and the classification step. As shown in FIG. 1, the toner manufactured in this way accumulates a certain amount of electric charge by frictional charging, and then develops the electrostatic latent image on the photoconductor to obtain a desired visible image. It is provided.
  Here, the charge accumulated in the toner due to frictional charging needs to be either positive or negative depending on the type of the photoreceptor on which the electrostatic latent image is formed. Further, the charge amount of the toner by frictional charging needs to be a sufficient amount to make the electrostatic latent image visible more accurately. Further, in recent years, as a photoconductive photoconductor for forming an electrostatic latent image, in place of a selenium photoconductor or an organic photoconductive photoconductor, it is pollution-free and has high sensitivity, and further has a Vickers strength of 1500 to 1500. Amorphous silicon photoconductors (hereinafter referred to as a-Si photoconductors) are frequently used because they have characteristics such as 2000 being very hard. Therefore, in order to develop the electrostatic latent image formed on the a-Si photoreceptor, it is desired to use a toner having excellent chargeability and durability.
  For this reason, not only a charge control agent and a conductive substance are added to the binder resin, but also inorganic oxides (fine powder) such as silica, aluminum oxide, titanium oxide, and zinc oxide are added to the toner (toner particles). Externally added, the polarity of the charge and the charge amount are controlled, and the durability and polishing properties are also controlled.
  However, these inorganic oxides are very hydrophilic because of the hydroxyl groups present on the surface. As a result, when added to toner, the fluidity and charge rise characteristics of the toner change due to the influence of humidity, and printing In some cases, there were adverse effects such as durability and reduced image density.
[0003]
  Therefore, in order to prevent the influence of such environmental conditions as humidity, the inorganic oxide is treated with a hydrophobizing agent or a polar group is introduced. For example, Japanese Patent No. 3101783 proposes a technique using titanium oxide treated with a hydrophobizing agent such as a silane coupling agent or a titanium coupling agent. Further, Japanese Patent Laid-Open Nos. 52-135739 and 10-3177 propose a technique using titanium oxide treated with a silane coupling agent such as an aminosilane compound in order to introduce a polar group. Yes.
  Further, JP-A-5-181306 discloses an electrostatic latent image in which abrasive fine particles such as alumina and zirconia are fixed on the surface of toner particles, and the ratio between the particle size of the toner particles and the particle size of the abrasive fine particles is controlled. Image developers have been proposed. According to this method, it is possible to obtain an excellent polishing effect on the surface of the photosensitive member, it is not necessary to incorporate a large system such as a cleaning brush, and the apparatus can be miniaturized, and against image flow, image density, fog, etc. effective.
[0004]
  However, this conventional technique has the following problems.
(1) In the prior art disclosed in Japanese Patent No. 3101783 and Japanese Patent Application Laid-Open No. 52-135739, etc., the polishing ability with respect to the surface of the photoreceptor is insufficient, and charge up is easily caused by polar groups. In particular, under low temperature and low humidity conditions, there are cases where problems such as a decrease in image density and fogging occur.
(2) Although the conventional technique disclosed in Japanese Patent Laid-Open No. 5-181306 can exhibit an appropriate polishing ability for the surface of the photoreceptor, charging characteristics are obtained under both high temperature and high humidity conditions and low temperature and low humidity conditions. May be unstable, or image defects such as a decrease in image density may occur.
[0005]
[Problems to be solved by the invention]
  As a result of diligent investigation of conventional problems, a plurality of hydrophobic inorganic metal abrasives having different degrees of hydrophobicity as external additivesTitanium oxide asCan be used to exhibit an appropriate polishing ability for the surface of the photoreceptor, and not only under high temperature and high humidity conditions (for example, 33 ° C., 85% RH) but also under low temperature and low humidity conditions (for example, 10 ° C., The inventors have found that an electrostatic latent image developing toner excellent in charging characteristics can be obtained even at 15% RH) and completed the present invention.
  That is, the object of the present invention is to exhibit an appropriate polishing ability for the surface of the photoreceptor, and the charge amount distribution is uniform even under high temperature and high humidity conditions and low temperature and low humidity conditions. An object of the present invention is to provide a toner for developing an electrostatic latent image that can provide stable image characteristics with little charge-up and an image forming method using the same.
[0006]
[Means for Solving the Problems]
  According to the present invention, for toner particles containing a binder resin and magnetic powder,Titanium oxide as a first hydrophobic inorganic metal abrasive having a different degree of hydrophobicity, and titanium oxide as a second hydrophobic inorganic metal abrasive,A toner for developing an electrostatic latent image that has been externally treated,The hydrophobicity of the first hydrophobic inorganic metal abrasive is set to a value within the range of 40 to 90, and the hydrophobicity of the second hydrophobic inorganic metal abrasive is set to a value within the range of less than 10-40. didAn electrostatic latent image developing toner is provided, which can solve the above-mentioned problems.
  That is, the first hydrophobic inorganic metal abrasiveTitanium oxide asBy adding, the toner charge amount distribution is uniform and the triboelectric charge amount is less reduced under high temperature and high humidity conditions. The second hydrophobic inorganic metal abrasiveTitanium oxide asIn addition to making the toner charge amount distribution uniform under low-temperature and low-humidity conditions, an appropriate polishing ability can be exerted on the photoreceptor surface, and a uniform thin layer can be formed on the developer carrier. Therefore, stable image characteristics can be obtained without charging up.
  The hydrophobicity of the hydrophobic inorganic metal abrasive can be measured by a methanol method.
[0007]
  In constructing the electrostatic latent image developing toner of the present invention, the difference between the hydrophobicity of the first hydrophobic inorganic metal abrasive and the hydrophobicity of the second hydrophobic inorganic metal abrasive is 10. A value in the range of ~ 70 is preferred.
  With this configuration, for electrostatic latent image development, the toner charge amount distribution is more uniform and less charged up in both high temperature and high humidity conditions and low temperature and low humidity conditions. Toner can be obtained.
[0008]
  Further, in constituting the electrostatic latent image developing toner of the present invention, the volume specific resistance of the first hydrophobic inorganic metal abrasive is set to a value of 6 MΩ · cm or more, and the second hydrophobic inorganic metal abrasive is used. It is preferable to make the volume resistivity of this value less than 6 MΩ · cm.
  With this configuration, for electrostatic latent image development, the toner charge amount distribution is more uniform and less charged up in both high temperature and high humidity conditions and low temperature and low humidity conditions. Toner can be obtained.
[0009]
  In forming the electrostatic latent image developing toner of the present invention, the average particle diameter of the first hydrophobic inorganic metal abrasive is set to a value less than 0.25 μm, and the second hydrophobic inorganic metal abrasive is used. It is preferable to set the average particle size of 0.25 μm or more.
  With this configuration, for electrostatic latent image development, the toner charge amount distribution is more uniform and less charged up in both high temperature and high humidity conditions and low temperature and low humidity conditions. Toner can be obtained.
[0010]
  Further, in constituting the electrostatic latent image developing toner of the present invention, the amount of the first hydrophobic inorganic metal abrasive added in the range of 0.01 to 10 parts by weight with respect to 100 parts by weight of the toner particles. It is preferable to set the amount of the second hydrophobic inorganic metal abrasive to a value within the range of 0.01 to 5 parts by weight.
  With this configuration, for electrostatic latent image development, the toner charge amount distribution is more uniform and less charged up in both high temperature and high humidity conditions and low temperature and low humidity conditions. Toner can be obtained.
[0011]
  Further, in constituting the electrostatic latent image developing toner of the present invention, the total amount of the first hydrophobic inorganic metal abrasive and the second hydrophobic inorganic metal abrasive is added to 100 parts by weight of the toner particles. The value is preferably in the range of 0.5 to 7 parts by weight.
  With this configuration, for electrostatic latent image development, the toner charge amount distribution is more uniform and less charged up in both high temperature and high humidity conditions and low temperature and low humidity conditions. Toner can be obtained.
[0012]
  Further, in constituting the electrostatic latent image developing toner of the present invention, the second hydrophobic inorganic metal polishing is performed with respect to the addition ratio of the first hydrophobic inorganic metal abrasive and the second hydrophobic inorganic metal abrasive. The addition amount of the agent is preferably set to a value within the range of 10 to 200 parts by weight with respect to 100 parts by weight of the first hydrophobic inorganic metal abrasive.
  With this configuration, for electrostatic latent image development, the toner charge amount distribution is more uniform and less charged up in both high temperature and high humidity conditions and low temperature and low humidity conditions. Toner can be obtained.
[0013]
  In forming the electrostatic latent image developing toner of the present invention, the first hydrophobic inorganic metal abrasive is anatase-type titanium oxide that has been hydrophobized, and the second hydrophobic inorganic metal abrasive. Is preferably a hydrophobized rutile-type titanium oxide.
  With this configuration, it is possible to obtain a toner for developing an electrostatic latent image that has a more uniform charge amount distribution in a high-temperature and high-humidity condition and a low-temperature and low-humidity condition and that is less likely to be charged up. it can.
[0014]
  In constituting the electrostatic latent image developing toner of the present invention, it is preferable to further contain silica fine particles as an external additive.
  With this configuration, an electrostatic latent image developing toner having excellent fluidity can be obtained.
[0015]
  Another aspect of the present invention provides a toner particle containing a binder resin and magnetic powder.Titanium oxide as a first hydrophobic inorganic metal abrasive having a different degree of hydrophobicity, and titanium oxide as a second hydrophobic inorganic metal abrasive,An image forming method using an electrostatic latent image developing toner externally treated,The hydrophobicity of the first hydrophobic inorganic metal abrasive is set to a value within the range of 40 to 90, and the hydrophobicity of the second hydrophobic inorganic metal abrasive is set to a value within the range of less than 10-40. didAn image forming method using an electrostatic latent image developing toner.
  By carrying out in this way, even under high temperature and high humidity conditions and low temperature and low humidity conditions, an image composed of toner for developing an electrostatic latent image can be obtained in which the toner charge amount distribution is more uniform and charging is less likely to occur. Obtainable.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the toner for developing an electrostatic latent image and an image forming method using the same according to the present invention will be described in detail. Needless to say, the present invention is not limited to these descriptions.
[0017]
[First embodiment]
  In the first embodiment, a first hydrophobic inorganic metal abrasive and a second hydrophobic inorganic metal abrasive having different degrees of hydrophobicity are externally added to toner particles containing a binder resin and magnetic powder. This is a processed electrostatic latent image developing toner.
That is, with respect to toner particles containing a binder resin and magnetic powder, titanium oxide as a first hydrophobic inorganic metal abrasive having a different degree of hydrophobicity and as a second hydrophobic inorganic metal abrasive And an electrostatic latent image developing toner externally treated with titanium oxide, wherein the hydrophobicity of the first hydrophobic inorganic metal abrasive is set to a value within the range of 40 to 90, and the second The toner for developing an electrostatic latent image, wherein the hydrophobicity of the hydrophobic inorganic metal abrasive is a value within the range of less than 10-40.
[0018]
1. Toner particles
  In the toner used in the first embodiment, an inorganic oxide is externally added to toner particles composed of, for example, a binder resin, waxes, a charge control agent, and magnetic powder according to actual conditions. Preferably it is.
[0019]
(1) Binder resin
  The type of the binder resin used for the toner used in the first embodiment is not particularly limited. For example, a styrene resin, an acrylic resin, a styrene-acrylic copolymer, a polyethylene resin, and a polypropylene resin are used. It is preferable to use thermoplastic resins such as resins, vinyl chloride resins, polyester resins, polyamide resins, polyurethane resins, polyvinyl alcohol resins, vinyl ether resins, N-vinyl resins, styrene-butadiene resins.
  The binder resin preferably has two molecular weight peaks (referred to as a low molecular weight peak and a high molecular weight peak). Specifically, the low molecular weight peak is in the range of 3,000 to 20,000, the other high molecular weight peak is in the range of 300,000 to 1,500,000, and Mw / Mn is 10 or more. Those are preferred. If the molecular weight peak is within such a range, the toner can be easily fixed, and offset resistance can be improved. The molecular weight of the binder resin can be determined by measuring the elution time from the column using a molecular weight measuring device (GPC) and comparing it with a calibration curve prepared in advance using a standard polystyrene resin. it can.
[0020]
  Moreover, in a binder resin, it is preferable to make a softening point into the value within the range of 110-150 degreeC, and it is more preferable to set it as the value within the range of 120-140 degreeC. This is because when the softening point of the binder resin is less than 110 ° C., the obtained toners are fused to each other, and the storage stability may be lowered. On the other hand, if the softening point of the binder resin exceeds 150 ° C., the toner fixability may be poor.
  Moreover, it is preferable to make the glass transition point (Tg) of binder resin into the value within the range of 55-70 degreeC, and it is more preferable to set it as the value within the range of 58-68 degreeC. This is because when the glass transition point of the binder resin is less than 55 ° C., the obtained toners are fused to each other, and the storage stability may be lowered. On the other hand, if the glass transition point of the binder resin exceeds 70 ° C., the toner fixability may be poor.
  The softening point and glass transition point of the binder resin can be determined from the endothermic peak position and the specific heat change point using a differential scanning calorimeter (DSC).
[0021]
(2) Waxes
  In addition, it is preferable to add waxes in order to obtain the effect of fixing property and offset property in the toner.
  The type of such wax is not particularly limited, but for example, one type of polyethylene wax, polypropylene wax, Teflon wax, Fischer Trop wax, paraffin wax, ester wax, montan wax, rice wax, etc. Single or 2 or more types of combinations are mentioned.
  In addition, when using Fischer-Tropsch wax, the thing whose molecular weight is a value of 1000 or more and has the endothermic bottom peak by DSC in the range of 100-120 degreeC is more preferable. As such Fischer-Tropsch wax, Sazol wax C1 (high molecular weight grade by crystallization of H1, endothermic bottom peak: 106.5 ° C.) available from Sazol, Sazol wax C105 (by fractional distillation of C1) Refined product, endothermic bottom peak: 102.1 ° C.), Sazol wax SPRAY (C105 fine particles, endothermic bottom peak: 102.1 ° C.), and the like.
  Also, the amount of added wax is not particularly limited. For example, when the total amount of toner is 100% by weight, the added amount of wax is set to a value in the range of 1 to 15 parts by weight. Is preferred.
  The reason for this is that when the amount of the wax added is less than 1 part by weight, offset to the fixing roll (fixing device) or image smearing may not be effectively prevented. This is because if the added amount of the wax exceeds 15 parts by weight, the toners are fused together, and the storage stability may be lowered.
[0022]
(3) Charge control agent
  In addition, in the toner, charge control and charge rising characteristics (indicator of whether to charge to a constant charge level in a short time) are remarkably improved, and charge control is performed from the viewpoint of obtaining excellent durability and stability characteristics. It is preferable to add an agent.
  The type of the charge control agent is not particularly limited. For example, positive charge such as nigrosine, a quaternary ammonium salt compound, a resin type charge control agent in which an amine compound is bonded to a resin, and the like. It is preferable to use a charge control agent exhibiting properties.
[0023]
  Further, when the total amount of toner is 100 parts by weight, the amount of charge control agent added is preferably set to a value in the range of 1.5 to 15 parts by weight.
  The reason for this is that when the amount of the charge control agent added is less than 1.5 parts by weight, it becomes difficult to stably impart charging characteristics to the toner, resulting in low image density and low durability. Tend. In addition, poor dispersion tends to occur, so-called fogging tends to occur, and photoconductor contamination tends to increase. On the other hand, when the addition amount of the charge control agent exceeds 15 parts by weight, there is a tendency that environmental resistance, in particular, charging failure and image failure under high temperature and high humidity, and defects such as photoconductor contamination tend to occur.
[0024]
(4) Magnetic powder
  In the toner, a known magnetic powder can be dispersed in the toner to constitute a magnetic toner. Preferred magnetic powder is a metal or alloy exhibiting ferromagnetism such as ferrite, magnetite, iron, cobalt, nickel, etc., a compound containing these ferromagnetic elements, or an appropriate heat treatment without containing ferromagnetic elements. An alloy that exhibits ferromagnetism can be cited. Moreover, it is preferable to make the average particle diameter of magnetic powder into the value within the range of 0.1-1 micrometer, and it is more preferable to set it as the value within the range of 0.1-0.5 micrometer. This is because the magnetic powder having such an average particle diameter is easy to handle, but can be uniformly dispersed in the toner binder in the form of fine powder.
  Moreover, it is preferable to surface-treat the surface of magnetic powder with surface treatment agents, such as a titanium coupling agent and a silane coupling agent. This is because the surface treatment can improve the hygroscopicity and dispersibility of the magnetic powder.
[0025]
2. External additive
(1) First hydrophobic inorganic metal abrasive
(1) -1 type
  As a kind of 1st hydrophobic inorganic metal abrasive | polishing agent,Although it is characterized by using titanium oxide, a combination of two or more of aluminum oxide, zirconium oxide and the like is also included.
  Titanium oxide includes anatase-type titanium oxide and rutile-type titanium oxide, both of which can be used favorably, but because an improvement in charging characteristics under high-temperature and high-humidity conditions, anatase-type titanium oxide is used. It is preferable to do.
[0026]
(1) -2 Hydrophobization degree
  Moreover, it is preferable to make the degree of hydrophobicity of the first hydrophobic inorganic metal abrasive a value within the range of 40 to 90.
  The reason for this is that when the degree of hydrophobicity is less than 40, there is a relationship with the degree of hydrophobicity of the second hydrophobic inorganic metal abrasive, but the charging characteristics of the toner under high temperature and high humidity conditions are significantly reduced. It is because there is a case to do. On the other hand, if the degree of hydrophobicity exceeds 90, charge-up is likely to occur, and problems such as a decrease in image density and fogging may occur under low temperature and low humidity conditions.
  Accordingly, the degree of hydrophobicity of the first hydrophobic inorganic metal abrasive is more preferably set to a value within the range of 45 to 75, and further preferably set to a value within the range of 50 to 70.
[0027]
(1) -3 average particle size
  The average particle diameter of the first hydrophobic inorganic metal abrasive is preferably less than 0.25 μm.
  This is because, when the average particle size is 0.25 μm or more, the variation in charge amount becomes large, which may cause a decrease in image density and a decrease in durability. Further, if the average particle size is 0.25 μm or more, the charging characteristics under high temperature and high humidity conditions may be significantly deteriorated.
  However, if the average particle size of the first hydrophobic inorganic metal abrasive is excessively small, the particles may be easily aggregated or the handling itself may be difficult.
  Accordingly, the average particle diameter of the first hydrophobic inorganic metal abrasive is preferably set to a value within the range of 0.01 to 0.22 μm, and more preferably within the range of 0.05 to 0.20 μm. Is more preferable.
[0028]
(1) -4 Surface treatment
  Moreover, it is preferable to treat the surface of the first hydrophobic inorganic metal abrasive with a silane compound or a titanium compound. This is because a hydrophobic group can be easily introduced onto the surface of the inorganic metal abrasive by performing such a surface treatment. Therefore, by using the first hydrophobic inorganic metal abrasive thus surface-treated, it is possible to prevent deterioration of charging characteristics particularly under high temperature and high humidity conditions.
  Here, preferable silane compounds include vinyltrimethoxysilane, naphthyltrimethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, isobutyltrimethoxysilane, octadecyltrimethoxysilane, naphthyl. Examples include triethoxysilane, phenyltriethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, isobutyltriethoxysilane, and octadecyltriethoxysilane.
  Preferred titanium compounds include isopropyl triisostearoyl titanium, vinyl trimethoxy titanium, naphthyltrimethoxy titanium, phenyl trimethoxy titanium, methyl trimethoxy titanium, ethyl trimethoxy titanium, propyl trimethoxy titanium, isobutyl trimethoxy titanium, octadecyl. Examples include trimethoxy titanium.
[0029]
(1) -5 Volume resistivity
  Further, the volume specific resistance of the first hydrophobic inorganic metal abrasive is preferably set to a value of 6 MΩ · cm or more.
  The reason for this is that if the volume resistivity is less than 6 MΩ · cm, there is a relationship with the volume resistivity of the second hydrophobic inorganic metal abrasive, but the charging characteristics of the toner under high temperature and high humidity conditions are also related. This is because there may be a significant decrease.
  However, if the volume specific resistance of the first hydrophobic inorganic metal abrasive becomes excessively large, charge-up is likely to occur or problems such as a decrease in image density and fogging may occur under low temperature and low humidity conditions. It is.
  Therefore, the volume resistivity of the first hydrophobic inorganic metal abrasive is more preferably set to a value in the range of 6.3 MΩ · cm to 10 MΩ · cm, and more preferably in the range of 6.6 MΩ · cm to 8 MΩ · cm. More preferably, it is a value.
[0030]
(1) -6 addition amount
  In addition, the amount of the first hydrophobic inorganic metal abrasive added is preferably set to a value in the range of 0.01 to 10 parts by weight with respect to 100 parts by weight of the toner particles.
  The reason for this is that when the amount added is less than 0.01 parts by weight, there is a relationship with the amount added of the second hydrophobic inorganic metal abrasive, but the charging characteristics under high temperature and high humidity conditions are significantly reduced. This is because the polishing ability to the original photoconductor may be reduced. On the other hand, when the added amount exceeds 10 parts by weight, charge-up is likely to occur, and troubles such as photoconductor contamination may occur. This is because it may cause
  Therefore, the amount of the first hydrophobic inorganic metal abrasive added is more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner particles. More preferably, the value is within the range of parts.
[0031]
(2) Second hydrophobic inorganic metal abrasive
(2) -1 type
  Similar to the type of the first hydrophobic inorganic metal abrasive,Although it is characterized by using titanium oxide, a combination of two or more of aluminum oxide, zirconium oxide and the like is also included.
  Further, when using titanium oxide, it is preferable to use rutile type titanium oxide because the charging characteristics under low temperature and low humidity conditions can be further improved.
[0032]
(2) -2 Hydrophobization degree
  Moreover, it is preferable to make the degree of hydrophobicity of the second hydrophobic inorganic metal abrasive a value within the range of less than 10-40.
  The reason for this is that when the degree of hydrophobicity is less than 10, there is a relationship with the degree of hydrophobicity of the first hydrophobic inorganic metal abrasive, but the charging characteristics under high temperature and high humidity conditions are significantly reduced. Because there is. On the other hand, if the degree of hydrophobicity exceeds 40, charge-up may easily occur.
  Accordingly, the degree of hydrophobicity of the second hydrophobic inorganic metal abrasive is more preferably set to a value within the range of 13 to 35, and further preferably set to a value within the range of 15 to 30.
[0033]
(2) -3 Average particle size
  The average particle diameter of the second hydrophobic inorganic metal abrasive is preferably 0.25 μm or more.
  This is because, when the average particle diameter is less than 0.25 μm, charge-up is likely to occur, and problems such as a decrease in image density and fogging may occur under low temperature and low humidity conditions.
  However, if the average particle size of the second hydrophobic inorganic metal abrasive is excessively large, it may be difficult to uniformly adhere to the toner particles.
  Therefore, the average particle diameter of the second hydrophobic inorganic metal abrasive is more preferably set to a value in the range of 0.27 to 1.0 μm, and a value in the range of 0.30 to 0.7 μm. Is more preferable.
[0034]
(2) -4 Surface treatment
  Moreover, it is preferable to treat the surface of the second hydrophobic inorganic metal abrasive with a silane compound or a titanium compound. This is because such a surface treatment can easily introduce a polar group and a hydrophobic group on the surface of the inorganic metal abrasive. Therefore, by using the second hydrophobic inorganic metal abrasive thus surface-treated, it is possible to prevent the charging characteristics from being deteriorated particularly under low temperature and low humidity conditions.
  Here, preferable silane compounds include vinyltrimethoxysilane, naphthyltrimethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, isobutyltrimethoxysilane, octadecyltrimethoxysilane, naphthyl. Triethoxysilane, phenyltriethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, isobutyltriethoxysilane, octadecyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxy Examples include silane, γ-methacryloxypropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane.
  Preferred titanium compounds include isopropyl triisostearoyl titanium, vinyl trimethoxy titanium, naphthyltrimethoxy titanium, phenyl trimethoxy titanium, methyl trimethoxy titanium, ethyl trimethoxy titanium, propyl trimethoxy titanium, isobutyl trimethoxy titanium, octadecyl. Examples include trimethoxy titanium.
[0035]
(2) -5 Volume resistivity
  Further, the volume specific resistance of the second hydrophobic inorganic metal abrasive is preferably set to a value less than 6 MΩ · cm.
  The reason for this is that when the volume resistivity is a value of 6 MΩ · cm or more, there is a relationship with the volume resistivity of the first hydrophobic inorganic metal abrasive, but charge-up is likely to occur, and under low temperature and low humidity conditions. This is because troubles may occur in the toner thin layer formation, and troubles such as a decrease in image density and fogging may occur.
  However, if the volume resistivity of the second hydrophobic inorganic metal abrasive is excessively small, it may be difficult to uniformly adhere to the toner particles. In addition, the charge amount of the toner may be reduced, resulting in problems such as durability stability and image density reduction.
  Therefore, the volume resistivity of the second hydrophobic inorganic metal abrasive is more preferably set to a value within the range of 0.00001 to 5 MΩ · cm, and more preferably within a range of 0.00001 to 3 MΩ · cm. Is more preferable.
[0036]
(2) -6 addition amount
  Further, the amount of the second hydrophobic inorganic metal abrasive added is preferably set to a value within the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the toner particles.
  The reason for this is that when the added amount is less than 0.01 parts by weight, there is a relationship with the added amount of the first hydrophobic inorganic metal abrasive, but a decrease in image density, fogging, etc. under low temperature and low humidity conditions. This is because there are cases in which the above-mentioned problems may occur. On the other hand, when the added amount exceeds 5 parts by weight, charge-up is likely to occur or excessive charging may occur under high temperature and high humidity conditions.
  Therefore, the amount of the second hydrophobic inorganic metal abrasive added is more preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the toner particles. More preferably, the value is within the range of parts.
[0037]
(3) Addition ratio
  Further, regarding the addition ratio of the first hydrophobic inorganic metal abrasive and the second hydrophobic inorganic metal abrasive, the addition amount of the second hydrophobic inorganic metal abrasive is set to the first hydrophobic inorganic metal abrasive. It is preferable to set it as the value within the range of 10-200 weight part with respect to 100 weight part of agents.
  The reason for this is that when the added amount of the second hydrophobic inorganic metal abrasive is less than 10 parts by weight, polishing is insufficient, image flow occurs at high temperature and high humidity, and at low temperature and low humidity, This is because the charge amount of the toner exceeds an appropriate value, fogging is likely to occur, and it is difficult to form a thin toner layer, and image defects are likely to occur.
On the other hand, when the added amount of the second hydrophobic inorganic metal abrasive exceeds 200 parts by weight, the toner tends to be poorly charged at high temperature and high humidity, and image defects such as a decrease in image density and contamination of the drum are caused. This is because there is a case where it is mixed. On the contrary, when the temperature is low and the humidity is low, the charge amount of the toner exceeds an appropriate value, which easily causes charge-up. As a result, the image density may be lowered and the durability may be deteriorated.
  Therefore, the amount of the second hydrophobic inorganic metal abrasive added is more preferably set to a value in the range of 20 to 100 parts by weight with respect to 100 parts by weight of the first hydrophobic inorganic metal abrasive. More preferably, the value is in the range of -70 parts by weight.
[0038]
(4) Total amount added
  Further, the total amount of addition of the first hydrophobic inorganic metal abrasive and the second hydrophobic inorganic metal abrasive is set to a value within the range of 0.5 to 15 parts by weight with respect to 100 parts by weight of the toner particles. It is preferable.
  The reason for this is that when the total addition amount is less than 0.5 parts by weight, the photoconductor drum is insufficiently polished or the charge amount is insufficient. For example, image flow occurs at high temperature and high humidity and low temperature and low humidity. This is because defects may easily occur. Further, when the total addition amount is less than 0.5 parts by weight, durability stability, image density reduction, and the like may occur. On the other hand, when the total addition amount exceeds 15 parts by weight, the fluidity of the toner is extremely deteriorated, which may cause a problem of image density reduction and durability deterioration. Furthermore, there are cases in which defects in peripheral parts such as contamination of the photosensitive drum may occur.
  Therefore, the total addition amount of the first hydrophobic inorganic metal abrasive and the second hydrophobic inorganic metal abrasive is a value within the range of 0.7 to 5.0 parts by weight with respect to 100 parts by weight of the toner particles. It is more preferable that the value be in the range of 0.9 to 4.0 parts by weight.
[0039]
3. Average particle size
  Further, the average particle diameter of the toner is not particularly limited, but for example, a value within the range of 5 to 12 μm is preferable.
  The reason for this is that when the average particle size of the toner is less than 5 μm, the charging characteristics and flow characteristics of the toner are lowered, and the liberation rate of the externally added particles may be increased. This is because if the average particle diameter of the toner exceeds 12 μm, the fluidity of the toner may be reduced due to insufficient external additives or image quality may be deteriorated.
  Therefore, the average particle diameter of the toner is more preferably set to a value within the range of 6 to 11 μm, and further preferably set to a value within the range of 7 to 10 μm.
[0040]
[Second Embodiment]
  The second embodiment is an image forming method using toner for developing an electrostatic latent image composed of toner particles and externally added particles, and a binder resin and magnetic powder are used as the toner for developing an electrostatic latent image. The toner for electrostatic latent image development in which a first hydrophobic inorganic metal abrasive having a different degree of hydrophobicity and a second hydrophobic inorganic metal abrasive are externally added to the toner particles contained therein are used. This is a featured image forming method.
That is, with respect to toner particles containing a binder resin and magnetic powder, titanium oxide as a first hydrophobic inorganic metal abrasive having a different degree of hydrophobicity, and titanium oxide as a second hydrophobic inorganic metal abrasive, Forming an electrostatic latent image developing toner subjected to external addition treatment, wherein the hydrophobicity of the first hydrophobic inorganic metal abrasive is set to a value within the range of 40 to 90, and the second An electrostatic latent image developing toner in which the hydrophobicity of the hydrophobic inorganic metal abrasive is set to a value in the range of less than 10 to 40 is used.
  Hereinafter, the contents already described in the first embodiment will be omitted, and different points will be described as the second embodiment.
[0041]
1. Image forming apparatus
(1) Configuration
  In carrying out the image forming method, the image forming apparatus 1 can be suitably used as shown in FIG. That is, the image forming apparatus 1 includes a developing device 10, a transfer roller 19, a cleaning blade 13, and the like around a charging type photosensitive drum (photosensitive member) 9 that rotates clockwise in the drawing along the rotation direction. A charging unit 8 is provided. The developing device 10 is provided with a developing roller 32. The surface of the developing roller 32 is spaced from the surface of the photosensitive member 9 by a predetermined distance. It is preferable that a predetermined amount of toner is appropriately supplied.
  Further, an optical transmission mechanism 5 for forming image dots on the surface of the photoconductor 9 is provided above the photoconductor 9. Although this optical transmission mechanism 5 is not shown, the polygon mirror 2 for reflecting the laser light from the laser light source, and the laser light on the surface of the photoreceptor between the charging unit 8 and the developing roller 32 via the reflection mirror 4. An optical system 3 for forming an image dot is preferably configured.
  In addition, a base portion 54 in which a control circuit 71 for controlling the device, which will be described later, is housed is provided at the lower portion of the image forming apparatus 1. It is arranged to be detachable. The recording paper container 55 is preferably provided with a storage 14 for storing recording paper before transfer.
  The recording paper placed on the pressing spring 52 is transported by the transport rollers 53 and 15 to the registration roller 18 provided facing the auxiliary roller 30 through the passages 16 and 17. Has been.
[0042]
  Further, a front door 50 is disposed on the right side of the image forming apparatus 1 so as to be openable and closable, and the recording paper placed on the front door is configured to be conveyed to the passage 17 by the conveyance roller 51. On the left side of the image forming apparatus 1, a fixing unit is configured by fixing rollers 23 and 24, and the recording paper that has passed between the photoreceptor 9 and the transfer roller 19 is fixed by these fixing rollers 23 and 24. In addition, it is preferable that the recording paper after fixing passes through the passage 27 by the conveying rollers 25 and 26 and is further accumulated in the transferred recording paper accumulator 6 by the rollers 28 and 29.
  Furthermore, it is preferable that a display unit 47 for displaying various information, an installation switch 48, and a power switch 49 are provided on the upper part of the image recording apparatus 1.
[0043]
(2) Operation
  In the image recording apparatus 1 configured as described above, the main motor (not shown) starts driving by opening and closing the power switch 49, and the photosensitive member 9 is rotated clockwise by the start switch (not shown). The optical transmission mechanism 5 is preferably configured so that an image can be formed on the surface of the photoreceptor 9.
  The formed image is developed by the developing roller 32 of the developing device 10, and the developed toner image is transferred to the recording paper by the transfer roller 19. Further, the recording paper onto which the toner has been transferred is fixed and fixed by the fixing rollers 23 and 24, and is conveyed to the stacker 6 by the rollers 25, 27, 28, and 29 and is collected. The toner that has not been developed by the developing roller 32 is collected by the cleaning blade 13.
  Therefore, in particular, in a positively charged type photoconductor such as an a-Si photoconductor, an image using the toner to which the first hydrophobic inorganic metal abrasive and the second hydrophobic inorganic metal abrasive are externally added in this way is used. By forming the toner, it is possible to effectively prevent toner adhesion and image flow over a long period of time under both environmental conditions of high temperature and high humidity and low temperature and low humidity.
[0044]
2. Toner for electrostatic latent image development
  The electrostatic latent image developing toner used in the second embodiment includes a first hydrophobic inorganic metal abrasive having a different degree of hydrophobicity and a second hydrophobicity with respect to toner particles containing a binder resin and magnetic powder. As long as it is an electrostatic latent image developing toner externally treated with a conductive inorganic metal abrasive, it can be preferably used, but the details are the same as those described in the first embodiment. Can do.
[0045]
【Example】
  Hereinafter, the present invention will be described in more detail based on examples. Needless to say, the following description exemplifies the present invention, and the scope of the present invention is not limited to the following description without any particular reason.
[0046]
[Example 1]
1. Toner creation
(1) Preparation of toner particles
  Styrene / acrylic resin, polyethylene wax, magnetite, and charge control agent were melt-kneaded with a twin screw extruder so as to have the following blending ratio, and then cooled. Subsequently, toner particles having an average particle size of 7 μm were obtained through a pulverization step and a classification step.
1) 50 parts by weight of styrene / acrylic resin
2) 2.5 parts by weight of low molecular weight polyethylene wax
3) Magnetite 45 parts by weight
4) Nigrosine compound 2.5 parts by weight
[0047]
(2) Addition of external additive particles
  The amount of the first hydrophobic inorganic metal abrasive is 1 part by weight and the second hydrophobic inorganic metal abrasive is 0.4 part by weight based on 100 parts by weight of the obtained toner particles. Thus, the toner of Example 1 was prepared by external addition.
1) 100 parts by weight of toner particles
2) 1st hydrophobic titanium oxide 1 part by weight
(Hydrophobicity 55, volume resistivity 10.9 MΩ · cm, average particle size 0.15 μm)
3) 0.4% by weight of second hydrophobic titanium oxide
(Hydrophobicity 15, volume resistivity 22.5 Ω · cm, average particle size 0.3 μm)
[0048]
2. Toner rating
  The obtained toner was configured as a magnetic one-component developer, and the initial image characteristics, durability, and image flow were evaluated using a Kyocera page printer (FS-3750) equipped with an a-Si photosensitive member. In addition, the charge amount was measured, and the results are shown in Table 1.
[0049]
(1) Solid image density
  After forming the solid image pattern using a Kyocera page printer (FS-3750) equipped with an a-Si photoconductor with toner as a magnetic one-component developer, the solid image density was measured using a Macbeth reflection densitometer (Macbeth). The measurement was performed using More specifically, density measurement was performed at any nine locations in the solid portion of the solid image pattern, and the average value was calculated to obtain the solid image density.
[0050]
(2) Image density
  Using toner as a magnetic one-component developer and forming an image using a Kyocera page printer (FS-3750) equipped with an a-Si photosensitive member, the uniformity of the image density was visually evaluated.
A: Image unevenness is not observed at all.
○: Image unevenness is hardly observed.
Δ: Some image unevenness is observed.
X: Image unevenness is observed remarkably.
[0051]
(3) Background fog
  An image was formed using a Kyocera page printer (FS-3750) equipped with an a-Si photosensitive member using toner as a magnetic one-component developer, and then background fogging was visually evaluated.
  The blocking property and fluidity in a high-temperature and high-humidity environment were determined by checking the operation of the toner sensor in the developing device, replenishment, and the change in image density. The toner thin layer on the developer carrying member in a low temperature and low humidity environment was visually inspected.
A: No background fogging is observed.
○: Background fog is hardly observed.
Δ: Background fog is slightly observed.
X: Background fog is remarkably observed.
[0052]
[Example 2]
1. Toner creation
  The total addition amount and addition ratio of the first hydrophobic inorganic metal abrasive and the second hydrophobic inorganic metal abrasive and the effect of adding silica particles as a fluidizing agent were examined. That is, as shown below, 0.7 parts by weight of the first hydrophobic titanium oxide and 0.7 parts by weight of the second titanium oxide with respect to 100 parts by weight of the toner particles prepared in the same manner as in Example 1. Then, the toner of Example 2 was prepared by externally adding the silica particles as a fluidization improver so as to have a ratio of 1 part by weight.
1) 100 parts by weight of toner particles
2) 0.7 part by weight of first hydrophobic titanium oxide
(Hydrophobicity 55, volume resistivity 10.9 MΩ · cm, average particle size 0.15 μm)
3) Second hydrophobic titanium oxide 0.7 parts by weight
(Hydrophobicity 15, volume resistivity 22.5 Ω · cm, average particle size 0.3 μm)
4) 1.0 part by weight of silica particles
[0053]
2. Toner rating
  The obtained toner was configured as a magnetic one-component developer, and the toner was evaluated in the same manner as in Example 1. As a result, when an image was formed with a printer FS-3750 manufactured by Kyocera, it was confirmed that a clear initial image was obtained. Further, as a result of continuous printing of 300,000 sheets under high temperature and high humidity conditions and low temperature and low humidity conditions, it was confirmed that clear images could be obtained.
[0054]
[Example 3]
1. Toner creation
  The effects of the types of the first hydrophobic inorganic metal abrasive and the second hydrophobic inorganic metal abrasive (hydrophobicity, volume resistivity, average particle diameter) were examined. That is, with respect to 100 parts by weight of toner particles prepared in the same manner as in Example 1, 0.7 parts by weight of the first hydrophobic titanium oxide and 0.7% of the second hydrophobic titanium oxide are shown as follows. The toner of Example 3 was prepared by externally adding parts by weight and silica particles as a fluidization improver in a proportion of 1 part by weight.
1) 100 parts by weight of toner particles
2) 1.0 part by weight of first hydrophobic titanium oxide
(Hydrophobicity 40, volume resistivity 17.9 MΩ · cm, average particle size 0.2 μm)
3) 0.4% by weight of second hydrophobic titanium oxide
(Hydrophobicity 25, volume resistivity 5.3 MΩ · cm, average particle size 0.15 μm)
4) 1.0 part by weight of silica particles
[0055]
2. Toner rating
  The obtained toner was configured as a magnetic one-component developer, and the toner was evaluated in the same manner as in Example 1. As a result, when an image was formed with a printer FS-3750 manufactured by Kyocera, it was confirmed that a clear initial image was obtained. Further, as a result of continuous printing of 300,000 sheets under high temperature and high humidity conditions and low temperature and low humidity conditions, the amount of the second hydrophobic titanium oxide added was slightly larger than the amount of the first hydrophobic titanium oxide added. This is probably due to a slight decrease in concentration.
[0056]
[Example 4]
  The total addition amount and addition ratio of the first hydrophobic inorganic metal abrasive and the second hydrophobic inorganic metal abrasive were examined. That is, the ratio of the first hydrophobic titanium oxide is 1.0 part by weight and the second hydrophobic titanium oxide is 0.1 part by weight with respect to 100 parts by weight of the toner particles prepared in the same manner as in Example 1. Thus, the toner of Example 4 was prepared by external addition.
  Next, when the same toner evaluation as in Example 1 was performed, it seems that the amount of the second hydrophobic titanium oxide added was relatively small, but background fogging occurred after continuous printing of about 10,000 sheets. . In addition, it was confirmed that after printing about 5000 sheets in a low temperature and low humidity environment, the toner thin layer on the developer carrying member is disturbed, and it becomes a little difficult to provide a stable image.
[0057]
[Example 5]
  The total addition amount and addition ratio of the first hydrophobic inorganic metal abrasive and the second hydrophobic inorganic metal abrasive were further examined. That is, the ratio of the first hydrophobic titanium oxide to 0.2 parts by weight and the second titanium oxide to 1.0 parts by weight with respect to 100 parts by weight of toner particles prepared in the same manner as in Example 1. The toner of Example 5 was prepared by adding each externally.
  Next, when the same toner evaluation as in Example 1 was performed, it is considered that the amount of the first hydrophobic titanium oxide added was relatively small, but the image density after continuous printing in a high temperature and high humidity environment decreased. In addition, it was confirmed that the toner fluidity was also lowered.
[0058]
  [Comparative Example 1]
  The effect of adding the first hydrophobic inorganic metal abrasive was examined. That is, the toner was prepared by adding 1.4 parts by weight of the second hydrophobic titanium oxide without adding the first hydrophobic titanium oxide in Example 1 to 100 parts by weight of the toner particles. .
  Next, the same toner evaluation as in Example 1 was performed. As a result, a clear image was obtained initially, but it was confirmed that the image density decreased significantly after continuous printing in a high temperature and high humidity environment and could not be used. It was done.
[0059]
[Comparative Example 2]
  The effect of adding the second hydrophobic inorganic metal abrasive was examined. That is, the toner was prepared by adding 1.4 parts by weight of the first hydrophobic titanium oxide without adding the second hydrophobic titanium oxide in Example 1 to 100 parts by weight of the toner particles. .
  Subsequently, the same toner evaluation as in Example 1 was performed, and background fogging occurred in the initial image. Further, in continuous printing under low temperature and low humidity conditions, the toner thin layer on the developer carrying member is disturbed, and a stable image cannot be provided.
[0060]
[Comparative Example 3]
  The effect of adding the first and second hydrophobic inorganic metal abrasives was examined. That is, in Example 1, a toner was prepared by adding only silica without adding the first and second hydrophobic titanium oxides.
  Next, the same toner evaluation as in Example 1 was performed, and a clear image was obtained. However, when about 10,000 sheets were printed, the developer adhered to the surface of the photoreceptor.
[0061]
[Table 1]

* In the evaluation of Comparative Example 3, the developer was remarkably adhered to the photoreceptor after continuous printing of 50,000 sheets, and stable image quality could not be obtained.
* In the evaluation of Example 4, the toner thin layer was disturbed after about 5000 sheets, and stable image quality could not be obtained, so the evaluation was stopped.
[0062]
【The invention's effect】
  According to the electrostatic latent image developing toner of the present invention and the image forming method using the same, the first hydrophobic inorganic metal abrasive having a different degree of hydrophobicity with respect to toner particles containing a binder resin and magnetic powderAs titanium oxide and, Second hydrophobic inorganic metal abrasiveAs titanium oxide andBy externally adding, the charging characteristics are stabilized and an excellent polishing effect on the photoconductor can be exhibited under any environmental conditions of high temperature and high humidity conditions and low temperature and low humidity conditions. A uniform thin layer can be formed. Accordingly, uniform charging characteristics and charge-up prevention properties can be exhibited under any environmental conditions, and as a result, high-quality images can be stably obtained over a long period of time.
[0063]
[Brief description of the drawings]
FIG. 1 is a diagram for explaining an internal structure and operation of a printer.
[0064]
[Explanation of symbols]
1: Image forming apparatus
2: Polygon mirror
5: Optical transmission mechanism
7: Upper door
9: Photoconductor
10: Developer
31: Toner container
32: Developing roller
33: Supply roller
39: Toner sensor
47: Display section

Claims (10)

Titanium oxide as a first hydrophobic inorganic metal abrasive having a different degree of hydrophobicity and titanium oxide as a second hydrophobic inorganic metal abrasive are separated from toner particles containing a binder resin and magnetic powder. A toner for developing an electrostatic latent image that has been subjected to an additive treatment,
The hydrophobicity of the first hydrophobic inorganic metal abrasive is set to a value within the range of 40 to 90, and the hydrophobicity of the second hydrophobic inorganic metal abrasive is within the range of less than 10 to 40. A toner for developing an electrostatic latent image, characterized by having a value . Claims, characterized in that a value within the range of the first and hydrophobicity of the hydrophobic inorganic metal abrasives, 10-70 the difference between the hydrophobicity of the second hydrophobic inorganic metal abrasives Item 2. The electrostatic latent image developing toner according to Item 1 . The volume specific resistance of the first hydrophobic inorganic metal abrasive is 6 MΩ · cm or more, and the volume resistivity of the second hydrophobic inorganic metal abrasive is less than 6 MΩ · cm. The electrostatic latent image developing toner according to claim 1 , wherein the toner is an electrostatic latent image developing toner. The average particle diameter of the first hydrophobic inorganic metal abrasive is set to a value of less than 0.25 μm, and the average particle diameter of the second hydrophobic inorganic metal abrasive is set to a value of 0.25 μm or more. The toner for developing an electrostatic latent image according to any one of claims 1 to 3 . The amount of the first hydrophobic inorganic metal abrasive added to 100 parts by weight of the toner particles is set to a value within the range of 0.01 to 10 parts by weight, and the second hydrophobic inorganic metal abrasive is used. The toner for developing an electrostatic latent image according to any one of claims 1 to 4, wherein the additive amount is set to a value within a range of 0.01 to 5 parts by weight. A total addition amount of the first hydrophobic inorganic metal abrasive and the second hydrophobic inorganic metal abrasive is set to a value within a range of 0.5 to 15 parts by weight with respect to 100 parts by weight of the toner particles. The electrostatic latent image developing toner according to claim 1, wherein the toner is an electrostatic latent image developing toner. Regarding the addition amount ratio of the first hydrophobic inorganic metal abrasive and the second hydrophobic inorganic metal abrasive, the addition amount of the second hydrophobic inorganic metal abrasive is set to the first hydrophobic inorganic metal abrasive 100. The electrostatic latent image developing toner according to claim 1, wherein the toner has a value within a range of 10 to 200 parts by weight with respect to parts by weight. The first hydrophobic inorganic metal abrasive is a hydrophobized anatase-type titanium oxide, and the second hydrophobic inorganic metal abrasive is a hydrophobized rutile-type titanium oxide. The toner for developing an electrostatic latent image according to any one of claims 1 to 7 . The electrostatic latent image developing toner according to claim 1 , wherein silica particles are further externally added to the toner particles. Titanium oxide as a first hydrophobic inorganic metal abrasive having a different degree of hydrophobicity and titanium oxide as a second hydrophobic inorganic metal abrasive are separated from toner particles containing a binder resin and magnetic powder. An image forming method using an electrostatic latent image developing toner subjected to an additive process,
The hydrophobicity of the first hydrophobic inorganic metal abrasive is set to a value within the range of 40 to 90, and the hydrophobicity of the second hydrophobic inorganic metal abrasive is within the range of less than 10 to 40. A method for forming an image, wherein the toner for developing an electrostatic latent image is used.

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