JP2016170234A - Two-component toner for electrostatic image development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-component toner that can suppress the occurrence of fogging on an image, dirt due to a toner remaining on a photoreceptor and charging roller, and the occurrence of filming resulting from the dirt.SOLUTION: There is provided a toner for electrostatic charge image development including toner base particles and an external additive, where the external additive includes boron nitride particles having an average primary particle diameter of 300 nm or more and less than 1000 nm and resin fine particles having an average primary particle diameter of 80 to 500 nm, and the content of the boron nitride particles is 0.01 to 0.60 parts by mass relative to 100 parts by mass of the toner base particles.SELECTED DRAWING: None

Description

  The present invention relates to a two-component toner for developing an electrostatic image.

  The electrophotographic image forming method can obtain high-quality printed matter (images, prints, etc.) at a high speed, so various printers, copiers, facsimiles, etc. (hereinafter these electrophotographic methods are summarized) Are also widely used. In this image forming method, an electrostatic charge image is formed by performing exposure according to a desired image on the surface of a charged photoreceptor, and then the electrostatic charge image developing toner (hereinafter simply referred to as an electrostatic charge image developing toner). (Also referred to as “toner”) is electrostatically attached to form a toner image on the surface of the photoconductor, and then this image is transferred to a recording medium such as paper, thereby forming a desired image on the recording medium. An image is formed.

  The image formed by the toner formed on the recording medium is in a powder form immediately after the image is formed, but is fixed on the recording medium through a fixing process of being heated and pressurized by a fixing roller. At this time, a resin component (referred to as a binder resin or a binder) and a release agent (wax) contained in the toner are once melted by heat, so that the powdered toner becomes a liquid melt, which is then By cooling, a film adhered to the surface of the recording medium is formed. This film corresponds to an image, printing, or the like fixed on a recording medium.

  Such image forming methods are classified into a one-component developing method and a two-component developing method depending on a method of charging toner particles for developing an electrostatic image. In the two-component development method, the toner particles and the carrier particles are agitated in the toner box, thereby causing friction between them and charging the toner particles. In the one-component development method, the toner particles are charged by friction between a charging blade provided near the outlet of the toner box and the toner particles without using carrier particles. Regardless of the method, it is important to stably charge the toner particles in order to stabilize the image quality. However, components such as wax contained in the toner particles adhere to the carrier and the charging blade and become dirty. If generated, the toner particles may become unstablely charged, causing fogging and an increase in the amount of toner used. In addition, since the toner is a fine particle, it easily aggregates. When such agglomeration occurs in the two-component toner, the mixing of the carrier and the toner particles becomes uneven, and the charging of the toner particles becomes unstable. In this case, as in the previous case, problems such as fogging and an increase in toner use amount occur.

  In addition, after the toner image formed on the surface of the photoconductor is transferred to the recording medium, cleaning is performed by using an elastic cleaning blade to remove the toner remaining on the surface of the photoconductor without being transferred. Is done. However, for example, after a long period of use, toner that has not been removed tends to remain on the surface of the photoreceptor after cleaning due to deterioration of the cleaning member, and the photoreceptor and the charging roller in contact with the photoreceptor are likely to remain. Filming may occur where film-like toner adheres to the surface. In this case, the charging of the photosensitive member becomes unstable, or contamination due to partial peeling of the film-like toner is caused, which also causes an image defect and an increase in the amount of toner used.

  From such a background, Patent Document 1 proposes that an inorganic layered substance is internally added in the toner base particles to suppress contamination of the photoreceptor, the developing blade, the cleaning blade, and the like even when used for a long time. Has been. Here, the internal addition means that a component is contained in the toner base particles, and is different from the external addition in which components are added separately from the toner base particles.

  Patent Document 2 discloses that 0.01 to 1.0 parts by mass of a compound having a plate-like shape is externally added to 100 parts by mass of toner particles, so that negative ghosts can be suppressed while keeping the toner tap density small. It has been proposed to do. In the toner proposed here, the increase in tap density is suppressed by utilizing the bulkiness of the compound, and therefore particles having a relatively large average particle diameter are selected. In fact, paragraph 0041 of Patent Document 2 mentions that if the average particle size of the plate-like fine particles is less than 1.0 μm, there is no effect in preventing negative ghosts. Relatively large particles having a diameter of 6 μm are used.

  Patent Document 3 proposes a one-component toner characterized by externally adding boron nitride having an average primary particle size of 1 to 40 μm. According to Patent Document 3, a fatty acid metal salt conventionally used for imparting lubricity between a cleaning blade and an image carrier (photoreceptor) imparts charge with a toner for one-component development. The problem is that the charge imparting member (charging blade) is contaminated and the chargeability is lowered, and lubricating with boron nitride instead of such components is the main point of the toner. In other words, the reason why boron nitride is used in this toner is to solve the problem that is a problem with a one-component toner, and a relatively large particle size of 1 μm or more is employed (for example, Patent Documents). 3 (see Table 1).

Japanese Patent No. 4863107 Japanese Patent No. 3457729 Japanese Patent No. 5598242

  As described above, the toner has been devised on various prescriptions in order to stabilize the chargeability of the toner to prevent image defects such as fogging, and to suppress contamination and filming of the photoreceptor and the charging roller. Has been proposed. The present invention has been made in view of the above circumstances, and a two-component toner capable of suppressing the occurrence of fog in an image, the stain due to the toner remaining on the photoreceptor or the charging roller, and the occurrence of filming associated with the stain. The purpose is to provide.

  As a result of intensive studies in order to solve the above problems, the present inventors have found that it is effective to add very fine resin fine particles having an average primary particle diameter of 50 to 500 nm as an external additive to suppress fogging. I found out. However, since the resin fine particles are fine spherical, it is difficult to collect what remains on the surface of the photoconductor by the cleaning blade, and the resin fine particles remaining on the surface of the photoconductor may newly cause filming. It also becomes a factor which contaminates a charging member. That is, even if the fog is eliminated by the addition of the resin fine particles, a new problem occurs. Under such circumstances, the present inventors use very fine boron nitride particles having an average primary particle diameter of 300 nm or more and less than 1000 nm as external additives in addition to the resin fine particles described above, and use them as toner base particles 100. It has been found that when 0.01 part by mass to 0.50 part by mass is added with respect to part by mass, both fogging and filming are suppressed, and the above-described problems in the two-component toner are solved. That is, the above-mentioned problems are solved for the first time by using resin fine particles having a predetermined primary particle diameter and boron nitride particles in combination. The present invention has been made based on the above findings, and specifically provides the following.

  The present invention is an electrostatic charge image developing toner comprising toner base particles and an external additive, wherein the external additive comprises boron nitride particles having an average primary particle diameter of 300 nm or more and less than 1000 nm, and an average primary particle diameter. A two-component toner for developing an electrostatic charge image, which contains resin fine particles of 80 to 500 nm and the content of the boron nitride particles is 0.01 to 0.60 parts by mass with respect to 100 parts by mass of the toner base particles. .

  The content of the boron nitride particles is preferably 0.15 parts by mass to 0.50 parts by mass with respect to 100 parts by mass of the toner base particles.

  The resin fine particles are preferably a copolymer of styrene and (meth) acrylic acid or an ester thereof.

  According to the present invention, there is provided a two-component toner capable of suppressing the occurrence of fog in an image, contamination of a charging roller, and the occurrence of filming in a photoreceptor.

  Hereinafter, an embodiment of the two-component toner for developing an electrostatic charge image of the present invention will be described.

  The two-component toner for developing an electrostatic image of the present invention (also simply referred to as “toner” as described above) is used in an image forming method in an electrophotographic system and used together with a carrier. The carrier is a particle in which a magnetic material such as magnetite is coated with a resin, and is stored in the toner box in a state of being mixed with the toner. When a plurality of carriers mixed with the toner are combined in a brush shape by the magnetic action on the surface of the magnetic roller adjacent to the photoconductor, and the surface of the photoconductor is boiled, the toner adhering to the surface of the carrier is removed. The electrostatic charge image is developed by transferring to the surface of the photoreceptor. The carrier content in the toner varies depending on the model, but is approximately several mass%.

  The carrier also has a role of charging the toner particles by causing friction with the toner particles by being stirred together with the toner in the toner box. However, as already described, since the toner particles are fine particles, they tend to aggregate. When such aggregation occurs in the toner box, the mixing between the carrier and the toner particles becomes uneven. There is a tendency that the charged state of the toner particles becomes unstable. In this case, an undesirable phenomenon associated with charging failure, such as fogging, is caused.

  The toner of the present invention comprises toner base particles and an external additive. In the present invention, by using a specific component as an external additive, fogging due to poor charging of the toner, contamination of the photoreceptor or charging roller, and filming in the photoreceptor or charging roller due to the contamination are generated. Since it has a feature in terms of suppression, conventional toner mother particles can be used. First, an example of such toner base particles will be described.

<Toner base particles>
The toner base particles are the main components of the toner containing a binder resin, a colorant, and a release agent. The toner base particles are mixed with the external additive as described above to form a toner. First, each component constituting the toner base particles will be described.

[Binder resin]
The binder resin is also called a binder and is one of the components contained in the toner base particles. The binder resin disperses the colorant contained in the toner base particles and solidifies after being melted on the surface of the recording medium by the heat of the fixing roller in the fixing process during printing, thereby fixing the colorant on the surface of the recording medium. Let

  The binder resin used in the toner of the present invention is not particularly limited, and conventionally known resins can be exemplified. Examples of such a binder resin include styrene copolymers such as polystyrene, styrene-methyl acrylate copolymer, styrene-acrylonitrile copolymer, and resin materials such as polyester and epoxy resin. These binder resins can be used alone or in combination of two or more. Among these binder resins, polyester can be preferably exemplified from the viewpoint of being easily colored and obtaining a clear color toner.

  The polyester can be obtained by polymerizing a monomer composition comprising a dihydric or higher polyhydric alcohol and a polybasic acid.

  Examples of the dihydric alcohol used for polyester polymerization include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1 Diols such as 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, bisphenol A alkylene such as bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A An oxide adduct etc. can be mentioned.

  Examples of the trihydric or higher polyhydric alcohol include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4. -Butanetriol, 1,2,5-pentanetriol, glycerin, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxy Mention may be made of methylbenzene and the like.

  Examples of the divalent polybasic acid include maleic acid, fumaric acid, citraconic acid, itaconic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, and anhydrides of these acids. .

  Examples of the tribasic or higher polybasic acid include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, and 2,5,7-naphthalenetricarboxylic acid. Acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2, Examples include 7,8-octanetetracarboxylic acid and anhydrides of these acids.

  The addition amount of the binder resin in the toner base particles may be appropriately set in consideration of the performance required for the toner, but as an example, it is 65 to 95 parts by weight in 100 parts by weight of the toner base particles. Can be mentioned.

[Colorant]
The colorant gives coloring power to the toner and is one of the components contained in the toner base particles. The colorant used in the toner of the present invention is not particularly limited, and various conventionally known pigments can be exemplified.

  Specifically, carbon black, black magnetic powder, etc. are exemplified as the black colorant, and copper phthalocyanine, methylene blue, Victoria blue, etc. are exemplified as the material of the cyan colorant, and the magenta colorant. Examples include rhodamine dyes, dimethylquinacridone, dichloroquinacridone, and carmine red. Examples of yellow colorants include benzidine yellow, chrome yellow, naphthol yellow, and disazo yellow. In addition, a colorant according to a desired color can be appropriately selected and used.

  The addition amount of the colorant in the toner base particles may be appropriately set in consideration of performance such as coloring power required for the toner, etc. As an example, 1 to 15 masses per 100 mass parts of the toner base particles. Part. Various master batches in which a high-concentration pigment is dispersed in advance in the resin are commercially available, and may be purchased and used as a colorant. In this case, the usage amount may be determined in consideration of the concentration of the pigment contained in the master batch so that the concentration of the pigment contained in the toner base particles is in the above range.

[Release agent]
The release agent is also called a wax and is one of the components contained in the toner base particles. The release agent is used to improve the release property between the fixing roller and the printing surface (more precisely, toner existing on the surface of a recording medium such as paper) in the fixing process during printing. .

  As the release agent, those usually used as a release agent for toner base particles can be used without particular limitation. Examples of such a release agent include polyolefin waxes such as polyethylene and polypropylene, hydrocarbon waxes such as Fischer-Tropsch wax, microcrystalline wax, and paraffin wax, pentaerythritol behenate, behenyl behenate, behenyl citrate, Examples include ester waxes such as montan ester wax, carnauba wax, rice wax, and Fischer tropish wax. These release agents can be used alone or in combination of two or more. Among these release agents, hydrocarbon waxes can be preferably exemplified.

  The amount of the release agent added to the toner base particles may be appropriately set in consideration of the performance required for the toner, but as an example, it is 2 to 12 parts by weight in 100 parts by weight of the toner base particles. Can be mentioned. When the addition amount of the release agent is within this range, good releasability between the fixing roller and the printing surface can be obtained in the fixing process during printing (that is, image formation or printing) and the toner can be separated from the toner base particles. Various troubles such as charging failure and filming due to leaching of the mold can be suppressed. The addition amount of the release agent in the toner base particles is more preferably 2 to 10 parts by weight, and further preferably 3.5 to 8 parts by weight with respect to 100 parts by weight of the toner base particles.

[Preparation of toner base particles]
Toner base particles are prepared from the above components. At this time, other components may be added according to various required aptitudes. In preparing the toner base particles, first, the various components described above are mixed, and then these components are kneaded while being heated to a temperature equal to or higher than the melting temperature of the binder resin. In kneading, a kneader such as a twin-screw extruder or a three-roll mill can be used. The kneaded material thus obtained is cooled and solidified, then pulverized by a pulverizer, and then classified to obtain toner base particles. There is no restriction | limiting in particular as a grinder used for the grinding | pulverization of a kneaded material, For example, a jet mill, a turbo mill, a rotor-type grinder etc. can be mentioned. The volume median particle size (D50) of the toner base particles after pulverization and classification is preferably exemplified by 4 to 10 μm, more preferably 5 to 9 μm.

  The volume median particle diameter (D50) is also called a volume-based median diameter, and the total volume of particles whose diameter is smaller than this value and the total volume of particles whose diameter is larger than this value are the total volume. Each value represents 50% of the total volume. The volume median particle size (D50) can be calculated by performing particle size distribution measurement. An example of such a particle size distribution measuring apparatus is “Multisizer 3” manufactured by Beckman Coulter.

<External additive>
The external additive is a particle component constituting the toner together with the toner base particles by being added to the toner base particles. In the present invention, boron nitride particles having an average primary particle diameter of 300 nm or more and less than 1000 nm are included as at least a part of the external additive.

  As already described, in the two-component toner, the carrier has a function of charging the toner particles by friction with the toner particles. At this time, if the toner particles, which are fine particles, are aggregated in the toner box, the carrier and the toner particles are not uniformly mixed, and the frictional charging of the toner particles becomes unstable. Problems such as fogging and an increase in the amount of toner used occur. As a result of studying measures for solving these problems, the present inventors surprisingly stabilized the charging of toner particles by using extremely fine resin fine particles having an average primary particle diameter of 80 to 500 nm as an external additive of the toner. It has been found that undesirable phenomena such as fogging and the like due to poor charging are suppressed. The reason why such an effect is obtained is not necessarily clear, but the presence of the resin fine particles as an external additive suppresses the aggregation of the toner particles, and the mixing between the carrier and the toner particles is performed uniformly. This is probably because of this.

  However, the extremely fine resin fine particles as described above tend to be difficult to be collected by the cleaning blade because of their fineness and spherical shape, and the resin fine particles remaining without being collected cause filming on the surface of the photoreceptor or the like. It will also be a factor. That is, the resin fine particles used to suppress the phenomenon such as fogging, in turn, cause other problems such as filming and contamination of the charging member. As a result of repeated investigations on a formulation that solves this problem and achieves both suppression of fogging and suppression of filming, the present inventors have found that in addition to the resin fine particles, the average primary particle size is 300 nm or more and less than 1000 nm. It has been found that fine boron nitride particles may be added as an external additive. The present invention has been made based on such knowledge, and the toner provided by the invention has extremely fine boron nitride particles having an average primary particle diameter of 300 nm or more and less than 1000 nm, and an average primary particle diameter of 80 to 500 nm. By including both of these extremely fine resin fine particles as external additives, the occurrence of filming and contamination of the charging member are suppressed, and the occurrence of problems such as image fogging and increased toner usage is suppressed.

  The reason why filming is suppressed by the addition of boron nitride particles is not necessarily clear, but is presumably due to the following reasons. The cleaning blade is made of an elastic body such as rubber, and collects unused toner while making line contact with the surface of the rotating photoreceptor. At this time, friction is generated between the cleaning blade, which is an elastic body, and the photosensitive member. If this friction increases, so-called chattering tends to occur as the cleaning blade tries to move as the photosensitive member rotates. It becomes. When such chattering occurs, the line contact between the cleaning blade and the photoconductor becomes unstable, and the above fine resin particles, which are extremely fine spherical bodies, pass through the cleaning blade and remain on the surface of the photoconductor. This may lead to filming or contamination of the charging member.

  In this respect, the boron nitride particles have a cleaving property and have an action of being easily cleaved by friction and adhering to the surface of the substance. The boron nitride adhering to the surface of the substance has a surface structure like graphite in which hexagonal meshes formed by alternately bonding nitrogen atoms and boron atoms are spread in a plane, like graphite. Shows lubricity. By adding such particles as an external additive, boron nitride particles cleaved by friction between the cleaning blade and the photoreceptor adhere to the surface of the photoreceptor and lubricate between the photoreceptor and the cleaning blade. It is presumed that chattering of the cleaning blade in the cleaning process is suppressed, the resin fine particle recovery rate is improved, and the occurrence of filming is suppressed. According to the study by the present inventors, such an action tends not to be obtained with a boron nitride particle having a large particle diameter. Therefore, in the present invention, as described above, the average primary particle diameter is 300 nm or more and less than 1000 nm. Very fine boron nitride particles are used.

  The average primary particle diameter of the boron nitride particles is preferably 300 nm to 800 nm, and more preferably 400 nm to 600 nm. The average primary particle size of the boron nitride particles means the volume median particle size (D50) of the primary particles of the particles, and can be known from the specification table of the manufacturer that manufactures the particles, or the toner base particles Can be obtained by a method similar to the calculation of D50.

  The amount of the boron nitride particles added as an external additive is 0.01 parts by mass to 0.60 parts by mass with respect to 100 parts by mass of the toner base particles. The amount of the boron nitride particles is preferably 0.05 parts by mass to 0.60 parts by mass with respect to 100 parts by mass of the toner base particles, and 0.15 parts by mass with respect to 100 parts by mass of the toner base particles. More preferably, it is -0.50 mass part. It is preferable that the amount of the boron nitride particles is 0.01 parts by mass or more with respect to 100 parts by mass of the toner base particles because contamination of the charging member and filming on the photosensitive member are suppressed. Further, it is preferable that the amount of boron nitride particles is 0.60 parts by mass or less with respect to 100 parts by mass of toner base particles because filming can be suppressed.

  The average primary particle diameter of resin fine particles used as an external additive together with the boron nitride particles is 80 to 500 nm, preferably 80 to 400 nm, and more preferably 80 to 300 nm. It is preferable that the average primary particle diameter of the resin fine particles is in the above range since fogging of an image can be satisfactorily suppressed. The average primary particle diameter of the resin fine particles can be obtained in the same manner as the boron nitride particles.

  As the resin fine particles, a copolymer of styrene and (meth) acrylic acid or an ester thereof is preferably selected. “(Meth) acrylic acid” means “acrylic acid or methacrylic acid”.

  The amount of the resin fine particles added as an external additive is preferably 0.3 parts by mass to 0.9 parts by mass with respect to 100 parts by mass of the toner base particles, and 0.4 parts by mass to 0.6 parts by mass. More preferably, it is part by mass.

  In the toner of the present invention, in addition to the above components, other components may be used as external additives. These components have the role of adhering to the surface of the toner base particles to improve the charging characteristics of the toner base particles or being separated from the toner base particles to improve the fluidity of the toner. . As such a component, inorganic oxide particles are preferably used.

  Examples of the inorganic oxide particles include silica, alumina, titania, zirconia, zinc oxide, chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, tellurium oxide, manganese oxide, and boron oxide. Among these, silica can be mentioned preferably. The inorganic oxide particles can be used alone or in combination of two or more.

  The surface of the inorganic oxide particles is preferably subjected to a hydrophobic treatment. As a method of hydrophobizing treatment, a conventionally known hydrophobizing agent is brought into contact with the surface of the inorganic oxide particle before hydrophobizing treatment, and a hydrophobic functional group or component is chemically bonded to the surface of the inorganic oxide particle. The method of making it attach or attach is mentioned. The hydrophobizing agent for hydrophobizing the inorganic oxide particles is not particularly limited, and conventionally known ones can be exemplified. Preferred examples of such a hydrophobizing agent include octyltriethoxysilane, polydimethylsiloxane, dimethyldichlorosilane, hexamethyldisilazane, and the like. These hydrophobizing agents can be used alone or in combination of two or more. Commercially available hydrophobized inorganic oxide particles may be used as the inorganic oxide particles.

  The amount of the inorganic oxide particles added as an external additive can be about 2 to 12 parts by mass with respect to 100 parts by mass of the toner base particles. Can do.

<Preparation of toner>
The toner is prepared by mixing the toner base particles and the external additive. At that time, other components may be appropriately added in order to improve various characteristics of the toner.

  Examples of the mixing device used when mixing the toner base particles and the external additive include a Henschel mixer and a super mixer. The mixing apparatus is not limited to these, and any mixing apparatus can be used as long as the apparatus can mix powder.

  Examples The two-component toner for developing an electrostatic charge image of the present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the following description, unless otherwise specified, “%” means “mass%” and “part” means “part by mass”.

[Preparation of toner base particles]
64.5 parts of a commercially available polyester resin (trade name: FC1565, manufactured by Mitsubishi Rayon Co., Ltd.) as a binder resin, and 15.6 of a polyester resin commercially available as a binder resin (trade name: ER561, manufactured by Mitsubishi Rayon Co., Ltd.) Parts, 11.9 parts of a yellow colorant (Pigment Yellow 180 colorant) as a colorant, and a resin charge control agent (trade name: Acrybase FCA-201-PS, manufactured by Fujikura Kasei Co., Ltd.) as a charge control agent 4 parts and 4 parts of fatty acid ester wax (trade name: WE-10, manufactured by NOF Corporation) as a release agent were mixed with a Henschel mixer, and then melt-kneaded using a twin-screw extruder. The obtained kneaded material is melted and solidified, coarsely pulverized with a funnel plex, then finely pulverized with a jet mill, classified using an air classifier, and positively charged toner having a volume median particle size of 7.5 μm. Mother particles were obtained.

[Toner Preparation]
After blending each material with the blending described in Tables 1 and 2, these were mixed for 10 minutes with a Henschel mixer to obtain toners of Examples 1 to 3 and Comparative Examples 1 to 6. In addition, the compounding quantity shown to Table 1 and 2 is a mass part. In Tables 1 and 2, “boron nitride particles A” are boron nitride particles having an average primary particle diameter of 500 nm, “boron nitride particles B” are boron nitride particles having an average primary particle diameter of 1500 nm, and “resin fine particles”. is a commercially available negative polarity styrene-acrylic resin particles having an average primary particle diameter of 100 nm (manufactured by Nippon paint Co., Ltd.), "silica" hexamethyldisilazane surface-treated with a plus polarity silica particles (BET surface area; 50 m ² / g).

[Evaluation of fog occurrence]
Using a non-magnetic two-component positive charging type color printer for evaluation, 13,000 sheets of a 5% printing rate chart were printed in an environment of a temperature of 25 ° C. and a humidity of 50%, and the occurrence of fogging was observed. . In addition, the evaluation when the fogging that is a practical problem is recognized as “×”, the fogging that is not a practical problem is determined as “◯”, and the intermediate evaluation is “△”. The results are shown in the “Fog” column of Tables 1 and 2. The amount of carrier added in the toner was about 4% by mass.

[Evaluation of contamination and filming]
Using the above color printer, after printing 25,000 sheets of a 5% printing chart in an environment of temperature 25 ° C. and humidity 50%, the state of occurrence of dirt and filming on the surface of the photoreceptor and the charging roller was observed. . The state of occurrence of dirt and filming at that time was evaluated according to the following evaluation criteria, and the results are shown in the “dirt / filming” column of Tables 1 and 2.
A: No occurrence of dirt and filming is observed. ○: Slight dirt is observed but there is no problem in printing. Δ: Some dirt is noticeable, but no filming occurs. X: Filming Was observed

  As shown in Tables 1 and 2, according to the two-component toner of the present invention, the occurrence of fogging in the image, the contamination due to the toner remaining on the photoreceptor or the charging roller, and the occurrence of filming due to the contamination are effective. It turns out that it can suppress.

Claims (3)

An electrostatic charge image developing toner comprising toner base particles and an external additive,
The external additive includes boron nitride particles having an average primary particle diameter of 300 nm or more and less than 1000 nm, and resin fine particles having an average primary particle diameter of 80 to 500 nm, and the content of the boron nitride particles is 100 parts by mass of the toner base particles. A two-component toner for developing an electrostatic charge image, in an amount of 0.01 to 0.60 parts by mass.   The two-component toner for developing electrostatic images according to claim 1, wherein the content of the boron nitride particles is 0.15 to 0.50 parts by mass with respect to 100 parts by mass of the toner base particles.   The two-component toner for developing an electrostatic charge image according to claim 1 or 2, wherein the resin fine particles are a copolymer of styrene and (meth) acrylic acid or an ester thereof.