JP2020034599A - Two-component developer - Google Patents

Abstract

To provide a two-component developer that can prevent variations in the amount of charge of toner before and after printing of a large number of sheets, while ensuring the amount of charge of toner suitable for image formation.SOLUTION: A two-component developer 100 contains a carrier including carrier particles 10 and a toner including toner particles 20. The carrier particles 10 each include a carrier core 11, a coat layer 12 covering the surface of the carrier core 11, and first resin particles 13 attached to the coat layer 12. The first resin particles 13 each include an embedded portion embedded into the surface of the coat layer 12, and a protruding portion protruding outward in a thickness direction of the coat layer 12. The toner particles 20 each include a toner base particle 21, and an external additive attached to the surface of the toner base particle 21. The external additive includes second resin particles 22. Both the first resin particles 13 and second resin particles 22 include a silicone resin. The mass of the first resin particles 13 is 0.03 parts by mass or more and 0.15 parts by mass or less based on 100 parts by mass of the carrier core 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a two-component developer.

  Resin-coated carriers are known. The carrier particles contained in the resin-coated carrier include a carrier core and a resin layer (coat layer) covering the surface of the carrier core (for example, see Patent Document 1). Further, a two-component developer containing a carrier and a toner is known.

JP 2009-193016 A

  However, using only the technique disclosed in Patent Document 1, it is possible to secure a charge amount of toner suitable for image formation and to suppress a change in charge amount of toner before and after printing a large number of sheets (for example, 100,000 sheets). It is difficult to provide a developer.

  The present invention has been made in view of the above-described circumstances, and it is possible to suppress a change in the charge amount of toner before and after printing a large number of sheets (for example, 100,000 sheets) while securing a charge amount of toner suitable for image formation. It is intended to provide a two-component developer.

  The two-component developer according to the present invention contains a carrier containing carrier particles and a toner containing toner particles. The carrier particles include a carrier core, a coat layer covering a surface of the carrier core, and first resin particles attached to the coat layer. The first resin particles include a buried portion buried in the surface of the coat layer and a protruding portion projecting outward in the thickness direction of the coat layer. The mass of the first resin particles is 0.03 parts by mass or more and 0.15 parts by mass or less based on 100 parts by mass of the carrier core. The toner particles include toner base particles including a binder resin, and an external additive attached to the surface of the toner base particles. The external additive includes second resin particles. Both the first resin particles and the second resin particles include a silicone resin.

  According to the present invention, it is possible to provide a two-component developer capable of suppressing fluctuations in the charge amount of toner before and after printing a large number of sheets (for example, 100,000 sheets) while securing the charge amount of toner suitable for image formation. it can.

FIG. 3 is a diagram illustrating an example of a cross-sectional structure of carrier particles and an example of a cross-sectional structure of toner particles included in a two-component developer according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of a surface layer in a cross section of the carrier particles shown in FIG. 1.

  Hereinafter, preferred embodiments of the present invention will be described. The carrier is an aggregate (for example, powder) of carrier particles. The toner is an aggregate (for example, powder) of toner particles. The external additive is an aggregate (for example, powder) of external additive particles. If the evaluation results (values indicating the shape, physical properties, etc.) of the powder (more specifically, the powder of resin particles, the powder of toner particles, and the powder of carrier particles) are not specified, It is the number average of the values obtained by selecting a considerable number of particles from the body and measuring each of the particles.

The measured value of the volume median diameter (D ₅₀ ) of the powder was measured using a laser diffraction / scattering type particle size distribution analyzer (“LA-950” manufactured by Horiba, Ltd.) unless otherwise specified. Median diameter. Unless otherwise specified, the number average primary particle diameter of the powder is equivalent to the circle equivalent diameter of 100 primary particles measured using a scanning electron microscope (Haywood diameter: having the same area as the projected area of the primary particles). (Diameter of a circle). The number average primary particle diameter of the particles refers to the number average primary particle diameter of the particles in the powder unless otherwise specified.

  Unless the strength of the charging property is specified, frictional charging is easy. For example, a standard carrier (standard carrier for negatively chargeable toner: N-01, standard carrier for positively chargeable toner: P-01) provided by the Imaging Society of Japan and a measurement target (for example, toner) are mixed and stirred. Then, the object to be measured is triboelectrically charged. Before and after the triboelectric charging, the charge amount of the object to be measured is measured with, for example, a Q / m meter (“MODEL 212HS” manufactured by Trek). A measurement object having a larger change in the charge amount before and after the triboelectric charging indicates a higher chargeability.

  Hereinafter, a compound and its derivative may be generically referred to by adding “system” after the compound name. When a polymer name is represented by adding “system” after the compound name, it means that the repeating unit of the polymer is derived from the compound or its derivative.

<Two-component developer>
The two-component developer according to this embodiment (hereinafter, sometimes referred to as a developer) contains a carrier containing carrier particles and a toner containing toner particles. The developer according to the exemplary embodiment can be suitably used for developing an electrostatic latent image. The toner included in the developer according to the exemplary embodiment can be used, for example, as a positively chargeable toner. The positively chargeable toner is positively charged due to friction with the carrier by being stirred together with the carrier.

  In the developer according to this embodiment, the carrier particles include a carrier core, a coat layer covering the surface of the carrier core, and first resin particles attached to the coat layer. The first resin particles include a buried portion buried in the surface of the coat layer and a protruding portion projecting outward in the thickness direction of the coat layer. The mass of the first resin particles is 0.03 parts by mass or more and 0.15 parts by mass or less based on 100 parts by mass of the carrier core. In the developer according to the exemplary embodiment, the toner particles include toner base particles including a binder resin and an external additive attached to the surface of the toner base particles. The external additive contains the second resin particles. Each of the first resin particles and the second resin particles contains a silicone resin.

  The developer according to the present exemplary embodiment has the above-described configuration, so that the variation in the charge amount of the toner before and after printing a large number of sheets (for example, 100,000 sheets) is ensured while securing the charge amount of the toner suitable for image formation. Can be suppressed. The reason is presumed as follows.

  In the developer according to the present embodiment, the first resin particles are partially embedded in the surface of the coat layer covering the carrier core. The mass of the first resin particles is 0.03 parts by mass or more based on 100 parts by mass of the carrier core. And the 1st resin particle contains silicone resin excellent in durability. Therefore, in the developer according to the present embodiment, peeling of the coat layer is suppressed even during printing of a large number of sheets (for example, 100,000 sheets). As a result, in the developer according to the exemplary embodiment, a decrease in the charge-imparting ability of the carrier during printing of a large number of sheets is suppressed. Further, in the developer according to the exemplary embodiment, the toner particles include an external additive including the second resin particles. And the 2nd resin particle contains a silicone resin. Therefore, in the developer according to the present embodiment, even when the first resin particles (resin particles including a silicone resin) migrate from the carrier particles to the toner particles during printing of a large number of sheets, the change in the chargeability of the toner particles is suppressed. Is done. Therefore, according to the developer according to the present embodiment, it is possible to suppress a change in the charge amount of the toner before and after printing a large number of sheets.

  In the developer according to the exemplary embodiment, the mass of the first resin particles is 0.15 parts by mass or less based on 100 parts by mass of the carrier core. As described above, in the developer according to the exemplary embodiment, the upper limit of the mass of the first resin particles is set so as not to hinder the charging of the toner. Therefore, according to the developer according to the exemplary embodiment, a charge amount of the toner suitable for image formation can be secured.

  In order to further suppress the variation in the charge amount of the toner before and after printing a large number of sheets, the mass of the coat layer is preferably 2 parts by mass or more and 10 parts by mass or less, and more preferably 3 parts by mass with respect to 100 parts by mass of the carrier core. It is more preferable that the amount is not less than 5 parts by mass and not more than 5 parts by mass.

  In order to easily secure the charge amount of the toner suitable for image formation and further suppress the fluctuation of the charge amount of the toner before and after printing a large number of sheets, the mass of the second resin particles is set to 100 parts by mass of the toner base particles. On the other hand, the amount is preferably 0.5 parts by mass or more and 1.5 parts by mass or less.

  The number average primary particle diameter of the first resin particles should be 40 nm or more and 200 nm in order to easily secure the charge amount of the toner suitable for image formation and further suppress the fluctuation of the charge amount of the toner before and after printing a large number of sheets. The following is preferred. For the same reason, the number average primary particle diameter of the second resin particles is preferably 40 nm or more and 200 nm or less. The first resin particles and the second resin particles may be resin particles of the same type or different resin particles. In order to further suppress the fluctuation of the charge amount of the toner before and after printing a large number of sheets, it is preferable that the first resin particles and the second resin particles are the same type of resin particles.

  Hereinafter, details of the developer according to the exemplary embodiment will be described with reference to the drawings as appropriate. In the drawings to be referred to, the respective components are schematically illustrated mainly for easy understanding, and the size, number, etc. of the illustrated components may be different from actual ones for the sake of drawing convenience. May be different.

[Configuration of developer]
The developer according to the exemplary embodiment contains a carrier containing carrier particles and a toner containing toner particles. FIG. 1 shows an example of a cross-sectional structure of carrier particles and an example of a cross-sectional structure of toner particles included in the developer according to the exemplary embodiment. FIG. 2 is a partially enlarged view of a surface layer in a cross section of the carrier particles shown in FIG.

  As shown in FIG. 1, the developer 100 contains a carrier containing carrier particles 10 and a toner containing toner particles 20. The carrier particles 10 include a carrier core 11, a coat layer 12 covering the surface of the carrier core 11, and first resin particles 13 (for example, a plurality of first resin particles 13) attached to the coat layer 12. The toner particles 20 include toner base particles 21 containing a binder resin, and an external additive attached to the surface of the toner base particles 21. The external additive includes the second resin particles 22 (for example, a plurality of second resin particles 22). Each of the first resin particles 13 and the second resin particles 22 contains a silicone resin. The mass of the first resin particles 13 is 0.03 parts by mass or more and 0.15 parts by mass or less based on 100 parts by mass of the carrier core 11.

  The toner particles 20 may be toner particles having no shell layer, or may be toner particles having a shell layer (hereinafter sometimes referred to as capsule toner particles). In the capsule toner particles, the toner base particles 21 include a toner core containing a binder resin and a shell layer covering the surface of the toner core. The shell layer contains a resin. For example, by covering a toner core that melts at a low temperature with a shell layer having excellent heat resistance, it is possible to achieve both heat-resistant storage stability and low-temperature fixability of the toner. The additive may be dispersed in the resin constituting the shell layer. The shell layer may cover the entire surface of the toner core, or may partially cover the surface of the toner core.

In order to obtain a toner suitable for image formation, the volume median diameter (D ₅₀ ) of the toner base particles 21 is preferably 4 μm or more and 9 μm or less.

  The toner base particles 21 may contain an internal additive (for example, at least one of a colorant, a release agent, and a charge control agent) as necessary in addition to the binder resin.

  As shown in FIG. 2, the first resin particles 13 include a buried portion 13 </ b> A buried in the surface of the coat layer 12 and the outside in the thickness direction Dr of the coat layer 12 (in the coat layer 12, the carrier core 11 side). Protruding portion 13B protruding to the opposite side). The protruding portion 13B is a portion of the surface of the coat layer 12 that protrudes outward in the thickness direction Dr of the coat layer 12 from a surface to which the first resin particles 13 are not attached (for example, the surface 12A shown in FIG. 2). It is.

In order to easily secure the charge amount of the toner suitable for image formation and further suppress the fluctuation of the charge amount of the toner before and after printing a large number of sheets, it is preferable that the first resin particles 13 satisfy the following conditions. That is, in the cross section of the first resin particles 13, the maximum length of the buried portion 13A in the thickness direction Dr of the coat layer 12 is L ^A, and the maximum length of the protruding portion 13B in the thickness direction Dr of the coat layer 12 is L. when is ^B, preferably satisfy the relation of ^{0.1 ≦ L a / (L a} + L B) ≦ 0.5. For the same reason, in the cross section of the first resin particles 13, the maximum length L ^A of the immersed part 13A, and a maximum length L ^B of the projecting portion 13B ^{is, 0.2 ≦ L A / (L} A + L B) It is more preferable to satisfy the relationship of ≦ 0.5. Hereinafter, L ^A / (L ^A + L ^B ) may be described as the burial ratio. The method of measuring the burial ratio is the same method as the embodiment described later or an alternative method thereof.

Note that L ^A corresponds to the maximum length of the buried portion 13A from the boundary 13C between the buried portion 13A and the protruding portion 13B in the thickness direction Dr of the coat layer 12. Further, L ^B is in the thickness direction Dr of the coating layer 12 corresponds to the maximum length of the projecting portion 13B of the boundary 13C between buried portion 13A and the projecting portion 13B. In FIG. 2, the surface 12 </ b> A is described as a straight line, but in actual carrier particles, the surface of the coat layer has a curved shape.

  The thickness of the coat layer 12 is not particularly limited as long as the coat layer 12 can cover the carrier core 11, but the toner charge amount before and after printing a large number of sheets while easily securing a charge amount of the toner suitable for image formation. Is preferably 30 nm or more and 5,000 nm or less in order to further suppress the occurrence of the light emission. In addition, the thickness of the coat layer 12 refers to the thickness of a portion of the coat layer 12 where the first resin particles 13 are not attached.

  The thickness of the coat layer 12 can be measured by analyzing a TEM (transmission electron microscope) photographed image of the cross section of the carrier particles 10 using commercially available image analysis software (for example, “WinROOF” manufactured by Mitani Corporation). The cross section of the carrier particles 10 can be manufactured using, for example, a cross section sample manufacturing apparatus (“Cross Section Polisher (registered trademark)” manufactured by JEOL Ltd.). The cross section of the carrier particles 10 may be dyed. If the thickness of the coat layer 12 is not uniform in one carrier particle 10, four evenly spaced portions (specifically, two straight lines orthogonal to each other at substantially the center of the cross section of the carrier particle 10 are drawn and the two straight lines are drawn) The thickness of the coat layer 12 is measured at each of the four points where the straight line intersects the coat layer 12, and the arithmetic average of the four measured values is used as the evaluation value of the carrier particles 10 (thickness of the coat layer 12). ).

  In order to easily secure the charge amount of the toner suitable for image formation and further suppress the fluctuation of the charge amount of the toner before and after printing a large number of sheets, the coat layer 12 must be 90% or more of the surface area of the carrier core 11. It preferably covers an area of 100% or less.

  The area ratio (coverage) occupied by the region covered by the coat layer 12 in the surface region of the carrier core 11 can be obtained by photographing a cross section of the carrier particles 10 (for example, the carrier particles 10 dyed in advance) with an electron microscope. The obtained captured image can be measured by analyzing the image using commercially available image analysis software (for example, “WinROOF” manufactured by Mitani Corporation).

In order to obtain good developability, the volume median diameter (D ₅₀ ) of the carrier core 11 is preferably from 15 μm to 150 μm, more preferably from 20 μm to 100 μm.

In order to obtain good developing property, the saturation magnetization of the applied magnetic field 3000 of the carrier core ^{11 (10 3 / 4π · A} / m) are the following 30A · m ² / kg or more 90A · m ² / kg It is more preferably 40 Am · m ² / kg or more and 80 Am · m ² / kg or less.

  The example of the configuration of the carrier particles and the example of the configuration of the toner particles included in the developer according to the exemplary embodiment have been described above with reference to FIGS. 1 and 2.

[Elements of developer]
Next, the components of the developer according to the exemplary embodiment will be described.

[Career element]
(Carrier core)
The carrier core preferably contains a magnetic material. The carrier core may be particles of a magnetic material, or a carrier core including a binder resin for a carrier core and particles of a magnetic material dispersed in the binder resin for a carrier core (hereinafter referred to as a resin carrier core). May be used.)

  Examples of the magnetic material contained in the carrier core include ferromagnetic metals (more specifically, iron, cobalt, nickel, and alloys containing one or more of these metals), and ferromagnetic metal oxides (more specifically, Include ferrite and the like. Preferred examples of ferrite include Ba ferrite, Mn ferrite, Mn-Zn ferrite, Ni-Zn ferrite, Mn-Mg ferrite, Ca-Mg ferrite, Li ferrite, Cu-Zn ferrite, and Mn-Mg-Sr ferrite. No. Further, as a preferred example of the ferromagnetic metal oxide, magnetite, which is a kind of spinel ferrite, may be mentioned. As the material of the carrier core, one type of magnetic material may be used alone, or two or more types of magnetic materials may be used in combination. As a method for producing the carrier core, for example, a method including a step of pulverizing and firing a magnetic material can be mentioned. In addition, you may use a commercial item as a carrier core.

  When the carrier core is particles of a magnetic material, preferred examples of the particles of the magnetic material include ferrite particles (ferrite core). Ferrite particles tend to have sufficient magnetism for image formation.

  When the carrier core is a resin carrier core, the binder resin for the carrier core contained in the resin carrier core is preferably at least one resin selected from the group consisting of a polyester resin, a urethane resin, and a phenol resin, and a phenol resin. Is more preferred. Examples of the particles of the magnetic material dispersed in the binder resin for a carrier core include particles containing at least one selected from the magnetic materials mentioned as examples of the magnetic material.

(Coat layer)
The coat layer is made of, for example, a resin. As the resin constituting the coat layer, a thermoplastic resin or a thermosetting resin may be used. Further, a thermoplastic resin and a thermosetting resin may be used in combination. Note that additives may be added to the coat layer. Examples of the additive include carbon black for adjusting the electric resistivity of the coat layer.

  As the thermoplastic resin for forming the coat layer, for example, a fluororesin, polystyrene, acrylic resin, styrene-acrylic acid copolymer, styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, polyvinyl chloride, Polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, polyvinyl pyrrolidone, novolak resin, low molecular weight polyethylene, aliphatic polyester resin, polyethylene terephthalate, polybutylene terephthalate, aromatic polyester resin (more specifically, polyarylate, etc.), polyamide resin , Polyacetal resin, polycarbonate resin, polyether sulfone resin, polysulfone resin, polyphenylene sulfide resin, and polyether ketone resin.

  As the thermosetting resin for forming the coat layer, for example, silicone resin, phenol resin, modified phenol resin, alkyd resin, epoxy resin, unsaturated polyester, urea resin, melamine resin, urea-melamine resin, guanamine resin, Examples include an acetoguanamine resin, a furan resin, a polyimide resin, a thermosetting polyamideimide resin, and a polyetherimide resin.

  In order to further suppress the fluctuation of the charge amount of the toner before and after printing a large number of sheets, the coat layer preferably contains a silicone resin. In order to further suppress the fluctuation of the charge amount of the toner before and after printing a large number of sheets, the silicone resin is preferably a methyl silicone resin or a methylphenyl silicone resin, and particularly preferably a methyl silicone resin. The silicone resin has a siloxane bond “Si—O—Si” as a main chain and an organic group as a side chain. The methyl silicone resin has only a methyl group as a side chain organic group. The methyl phenyl silicone resin has only a methyl group and a phenyl group as side chain organic groups. In order for the silicone resin to have excellent durability, it is preferable that the main chains (siloxane bonds: Si-O-Si) of the silicone resin are three-dimensionally connected to each other.

  Further, in order to further suppress the fluctuation of the charge amount of the positively chargeable toner before and after printing a large number of sheets, while increasing the charge imparting ability of the carrier particles to the positively chargeable toner, the coat layer contains a fluorine resin and a silicone resin Is preferred. Since the fluororesin has strong negative chargeability, when the coat layer contains the fluororesin, the ability of the carrier particles to charge the positively chargeable toner can be enhanced.

  Examples of the fluorine resin that can be used as the constituent resin of the coat layer include polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene (PTFE), and polytrifluoroethylene (more specifically, polychlorotrifluoroethylene and the like). Examples include polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA). In order to further enhance the charge imparting ability of the carrier particles to the positively chargeable toner, FEP is preferable as the fluororesin that can be used as the constituent resin of the coat layer.

  When the coat layer contains a fluorine resin and a silicone resin, the mass ratio of the fluorine resin to the silicone resin in the coat layer (fluorine resin / silicone resin) is, for example, 1/4 or more and 4/1 or less. Further, when the coating layer contains a fluorine resin and a silicone resin, in order to further suppress the fluctuation of the charge amount of the positively chargeable toner before and after printing a large number of sheets, while further increasing the charge imparting ability of the carrier particles to the positively chargeable toner. It is preferable that the total mass of the fluororesin and the silicone resin in the coat layer is 90% by mass or more and 100% by mass or less based on the whole coat layer.

(First resin particles)
The first resin particles include a silicone resin. In order to further suppress the fluctuation of the charge amount of the toner before and after printing a large number of sheets, the silicone resin contained in the first resin particles is preferably a methyl silicone resin and a methylphenyl silicone resin, and particularly preferably a methyl silicone resin.

  In order to further suppress the fluctuation of the charge amount of the toner before and after printing a large number of sheets, the content of the silicone resin in the first resin particles is 80% by mass or more and 100% by mass or less based on the entire first resin particles. And more preferably 90% by mass or more and 100% by mass or less.

  The method for preparing the first resin particles is not particularly limited as long as the method can prepare resin particles containing a silicone resin. An example of a method for preparing the first resin particles will be described later in Examples. In addition, you may use a commercial item as a 1st resin particle.

(Combination of materials)
In order to easily secure the charge amount of the positively chargeable toner suitable for image formation and further suppress the fluctuation in the charge amount of the positively chargeable toner before and after printing a large number of sheets, the coating layer should be made of a fluororesin or a methyl silicone resin. And the first resin particles preferably include a methyl silicone resin. For the same reason, it is more preferable that the coat layer contains a fluorine resin and a methyl silicone resin, the first resin particles contain a methyl silicone resin, and the number average primary particle diameter of the first resin particles is 40 nm or more and 200 nm or less.

[Toner element]
Next, the components of the toner will be described.

(Binder resin)
The binder resin occupies most of the toner base particles (for example, 70% by mass or more) of all components. In order to obtain a toner having excellent low-temperature fixability, the toner base particles preferably contain a thermoplastic resin as a binder resin, and contain a thermoplastic resin in a proportion of 85% by mass or more of the entire binder resin. Is more preferred. Examples of the thermoplastic resin include a styrene resin, an acrylate resin, an olefin resin (more specifically, a polyethylene resin and a polypropylene resin), a vinyl resin (more specifically, a vinyl chloride resin, a polyvinyl resin, and the like). Alcohol, vinyl ether resin, N-vinyl resin, etc.), polyester resin, polyamide resin, and urethane resin. Further, a copolymer of each of these resins, that is, a copolymer in which an arbitrary repeating unit is introduced into the resin (more specifically, a styrene-acrylate resin, a styrene-butadiene resin, etc.) It can be used as a binder resin.

  The thermoplastic resin is obtained by subjecting one or more thermoplastic monomers to addition polymerization, copolymerization, or polycondensation. The thermoplastic monomer is a monomer that becomes a thermoplastic resin by homopolymerization (more specifically, an acrylate monomer or a styrene monomer) or a monomer that becomes a thermoplastic resin by polycondensation (for example, polycondensation). Is a combination of a polyhydric alcohol and a polycarboxylic acid).

  In order to obtain a toner having excellent low-temperature fixability, it is preferable that the toner base particles contain a polyester resin as a binder resin, and the polyester resin is contained in a proportion of 80% by mass or more and 100% by mass or less of the whole binder resin. Is more preferable. The polyester resin is obtained by polycondensing one or more polyhydric alcohols and one or more polyhydric carboxylic acids. Examples of the alcohol for synthesizing the polyester resin include the following dihydric alcohols (more specifically, aliphatic diols and bisphenols), and trihydric or higher alcohols. Examples of the carboxylic acid for synthesizing the polyester resin include a divalent carboxylic acid and a trivalent or higher carboxylic acid as shown below. In place of the polycarboxylic acid, a polycarboxylic acid derivative capable of forming an ester bond by condensation polymerization of a polycarboxylic acid anhydride, a polycarboxylic acid halide, or the like may be used.

  Preferred examples of the aliphatic diol include diethylene glycol, triethylene glycol, neopentyl glycol, 1,2-propanediol, α, ω-alkanediol (more specifically, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,12-dodecanediol, etc.) , 2-butene-1,4-diol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

  Suitable examples of bisphenol include bisphenol A, hydrogenated bisphenol A, bisphenol A ethylene oxide adduct, and bisphenol A propylene oxide adduct.

  Preferred examples of the trihydric or higher alcohol include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butane Triol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5- Trihydroxymethylbenzene.

  Preferred examples of divalent carboxylic acids include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, azelaic acid, malonic acid , 1,10-decanedicarboxylic acid, succinic acid, alkyl succinic acid (more specifically, n-butyl succinic acid, isobutyl succinic acid, n-octyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, etc.), And alkenyl succinic acids (more specifically, n-butenyl succinic acid, isobutenyl succinic acid, n-octenyl succinic acid, n-dodecenyl succinic acid, isododecenyl succinic acid, etc.).

  Preferred examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) Methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empol trimer acid.

(Colorant)
The toner base particles may contain a colorant. As the colorant, a known pigment or dye can be used according to the color of the toner. In order to form a high-quality image using the toner, the amount of the colorant is preferably from 1 part by weight to 20 parts by weight based on 100 parts by weight of the binder resin.

  The toner base particles may contain a black colorant. An example of a black colorant is carbon black. Further, the black colorant may be a colorant that is toned to black using a yellow colorant, a magenta colorant, and a cyan colorant.

  The toner base particles may contain a colorant. Color colorants include yellow, magenta, and cyan colorants.

  As the yellow colorant, for example, one or more compounds selected from the group consisting of condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and arylamide compounds can be used. Examples of the yellow colorant include C.I. I. Pigment Yellow (3, 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155) , 168, 174, 175, 176, 180, 181, 191 and 194), naphthol yellow S, Hansa yellow G, and C.I. I. Bat yellow.

  As the magenta colorant, for example, selected from the group consisting of condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. One or more compounds can be used. Examples of the magenta colorant include C.I. I. Pigment Red (2, 3, 5, 6, 7, 19, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 144, 146, 150, 166, 169, 177) , 184, 185, 202, 206, 220, 221 and 254).

  As the cyan colorant, for example, one or more compounds selected from the group consisting of copper phthalocyanine compounds, anthraquinone compounds, and basic dye lake compounds can be used. Examples of the cyan colorant include C.I. I. Pigment Blue (1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, and 66), phthalocyanine blue, C.I. I. Bat blue, and C.I. I. Acid Blue.

(Release agent)
The toner base particles may contain a release agent. The release agent is used, for example, to obtain a toner having excellent offset resistance. In order to obtain a toner having excellent offset resistance, the amount of the release agent is preferably from 1 part by weight to 20 parts by weight based on 100 parts by weight of the binder resin.

  Examples of the release agent include ester wax, polyolefin wax (more specifically, polyethylene wax, polypropylene wax, etc.), microcrystalline wax, fluororesin wax, Fischer-Tropsch wax, paraffin wax, candelilla wax, montan wax, And caster wax. Examples of the ester wax include natural ester waxes (more specifically, carnauba wax, rice wax, and the like), and synthetic ester waxes. In the present embodiment, one type of release agent may be used alone, or a plurality of types of release agents may be used in combination.

  In order to improve the compatibility between the binder resin and the release agent, a compatibilizer may be added to the toner base particles.

(Charge control agent)
The toner base particles may contain a charge control agent. The charge control agent is used, for example, to obtain a toner having excellent charge stability or charge rising characteristics. The charge rising characteristic of the toner is an index of whether or not the toner can be charged to a predetermined charge level in a short time.

  By including a positively chargeable charge control agent in the toner base particles, the cationicity (positive chargeability) of the toner base particles can be enhanced. Further, by adding a negatively chargeable charge control agent to the toner base particles, the anionicity (negative chargeability) of the toner base particles can be enhanced.

  Examples of positively chargeable charge control agents include pyridazine, pyrimidine, pyrazine, 1,2-oxazine, 1,3-oxazine, 1,4-oxazine, 1,2-thiazine, 1,3-thiazine, 4-thiazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6- Oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1,2,3,4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1, Azine compounds such as 2,4,6-oxatriazine, 1,3,4,5-oxatriazine, phthalazine, quinazoline, quinoxaline; azine fast red FC, azine fast red 12BK, azine biore Direct dyes such as BO, azine brown 3G, azine light brown GR, azine dark green BH / C, azine deep black EW, azine deep black 3RL; acid dyes such as nigrosine BK, nigrosine NB, nigrosine Z; Amine; alkylamide; quaternary ammonium salts such as benzyldecylhexylmethylammonium chloride, decyltrimethylammonium chloride, 2- (methacryloyloxy) ethyltrimethylammonium chloride, and dimethylaminopropylacrylamide methyl chloride quaternary salt; Resin. One of these charge control agents may be used alone, or two or more thereof may be used in combination.

  Examples of the negatively chargeable charge control agent include an organometallic complex which is a chelate compound. As the organometallic complex, an acetylacetone metal complex, a salicylic acid-based metal complex, and salts thereof are preferable.

  In order to obtain a toner having excellent charge stability, the content of the charge control agent is preferably 0.1 part by mass or more and 10 parts by mass or less based on 100 parts by mass of the binder resin.

(External additives)
The toner particles included in the developer according to the exemplary embodiment include an external additive attached to the surface of the toner base particles. The external additive contains the second resin particles. The second resin particles include a silicone resin. As a silicone resin contained in the second resin particles, a methyl silicone resin and a methyl phenyl silicone resin are preferable, and a methyl silicone resin is particularly preferable, in order to further suppress the fluctuation of the charge amount of the toner before and after printing a large number of sheets.

  In order to further suppress the fluctuation of the charge amount of the toner before and after printing a large number of sheets, the content of the silicone resin in the second resin particles is 80% by mass or more and 100% by mass or less based on the entire second resin particles. And more preferably 90% by mass or more and 100% by mass or less.

  The method for preparing the second resin particles is not particularly limited as long as the method can prepare resin particles containing a silicone resin. An example of a method for preparing the second resin particles will be described later in Examples. In addition, you may use a commercial item as a 2nd resin particle.

  The external additive may include only the second resin particles as the external additive particles, or may include other external additive particles in addition to the second resin particles. In order to maintain good fluidity of the toner, inorganic particles are preferable as other external additive particles. Examples of the inorganic particles include silica particles and particles of a metal oxide (more specifically, titania, alumina, magnesium oxide, zinc oxide, and the like).

  Other external additive particles may be surface-treated. For example, when silica particles are used as other external additive particles, hydrophobicity and / or positive chargeability may be imparted to the surface of the silica particles by a surface treatment agent. Examples of the surface treatment agent include a coupling agent (more specifically, a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, etc.), a silazane compound (more specifically, a chain silazane compound, Cyclic silazane compound) and silicone oil (more specifically, dimethyl silicone oil and the like). As the surface treatment agent, a silane coupling agent and a silazane compound are particularly preferable. Preferred examples of the silane coupling agent include silane compounds (more specifically, methyltrimethoxysilane, aminosilane, and the like). A preferred example of the silazane compound is HMDS (hexamethyldisilazane). When the surface of a silica substrate (untreated silica particles) is treated with a surface treatment agent, a large number of hydroxy groups (—OH) present on the surface of the silica substrate are partially or entirely derived from the surface treatment agent. To a functional group. As a result, silica particles having on the surface functional groups derived from the surface treatment agent (specifically, functional groups that are more hydrophobic and / or positively charged than hydroxy groups) are obtained.

  In order to sufficiently exert the function of the external additive while suppressing the detachment of the external additive from the toner base particles, the amount of the external additive (when using other external additive particles, The total amount of the resin particles and other external additive particles) is preferably 0.5 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the toner base particles.

<Developer manufacturing method>
Next, a preferred method of manufacturing the developer according to the above-described embodiment will be described. Specifically, a method for manufacturing a carrier, a method for manufacturing a toner, and a method for mixing a carrier and a toner will be described. Hereinafter, description of components overlapping with the developer according to the above-described embodiment will be omitted.

[Method for producing carrier]
First, a preferred method for manufacturing a carrier will be described. A preferred method for producing a carrier described below includes a step of preparing a carrier core and a step of forming a coat layer. Further, a preferred method for producing a carrier described below is a method in which the formation of the coat layer and the attachment of the first resin particles to the coat layer are simultaneously performed.

(Process of preparing carrier core)
First, the raw material of the carrier core and water are mixed to obtain a mixture. Next, the raw materials in the mixture are ground using a wet ball mill. Next, the mixture containing the pulverized raw materials is dried and granulated using, for example, a spray drier. Thereafter, the dried granules are fired to obtain a carrier core.

(Coating layer forming step)
First, a liquid containing a coating layer material (coat layer forming solution) is sprayed onto a carrier core in a fluidized bed using a fluidized coating apparatus to form a coating film on the surface of the carrier core. At this time, for example, by changing at least one of the concentration of the raw material in the coat layer forming solution and the spray amount of the coat layer forming solution, the mass of the coat layer with respect to 100 parts by mass of the carrier core in the obtained carrier particles is adjusted. it can.

  Next, the first resin particles containing the silicone resin are charged into the fluid coating apparatus, and the first resin particles are adhered to the coating film (the coating film before the heat treatment) formed on the surface of the carrier core. Since the surface of the coating film before the heat treatment is not cured, the first resin particles adhere to the surface of the coating film in a state where the first resin particles bite. At this time, for example, the burying ratio of the first resin particles can be adjusted by changing the concentration of the raw material in the coating film. Further, by changing the amount of the first resin particles charged, the mass of the first resin particles with respect to 100 parts by mass of the carrier core in the obtained carrier particles can be adjusted.

  Next, a carrier particle comprising a carrier core, a coat layer covering the surface of the carrier core, and first resin particles adhered to the coat layer by heat-treating the fluidized bed in the fluidized coating apparatus and curing the coating film. Powder (carrier) is obtained. According to the method described above, a part of the first resin particles can be embedded in the surface of the coat layer because the coating film is cured in a state where the first resin particles bite into the surface of the coating film.

[Method of Manufacturing Toner]
Next, a preferred method for producing the toner will be described. A preferred method for producing a toner described below includes a step of preparing toner base particles and an external addition step.

(Preparation process of toner base particles)
First, toner base particles are prepared by an aggregation method or a pulverization method.

  The aggregation method includes, for example, an aggregation step and a coalescence step. In the aggregating step, fine particles containing the components constituting the toner base particles are aggregated in an aqueous medium to form aggregated particles. In the coalescing step, the components contained in the aggregated particles are coalesced in an aqueous medium to form toner base particles.

  Next, the pulverization method will be described. According to the pulverization method, the toner base particles can be prepared relatively easily, and the production cost can be reduced. When the toner base particles are prepared by the pulverization method, the preparation step of the toner base particles includes, for example, a melt-kneading step and a pulverizing step. The step of preparing the toner base particles may further include a mixing step before the melt-kneading step. The step of preparing the toner base particles may further include at least one of a pulverizing step and a classifying step after the pulverizing step.

  In the mixing step, the binder resin is mixed with an internal additive to be added as necessary to obtain a mixture. In the melt-kneading step, the toner material is melted and kneaded to obtain a melt-kneaded product. As the toner material, for example, a mixture obtained in a mixing step is used. In the pulverizing step, the obtained melt-kneaded product is cooled to, for example, room temperature (25 ° C.) and then pulverized to obtain a pulverized product. If it is necessary to reduce the diameter of the pulverized material obtained in the pulverizing step, a step of further pulverizing the pulverized substance (fine pulverizing step) may be performed. When the particle size of the pulverized material is made uniform, a step of classifying the obtained pulverized material (classification step) may be performed. Through the above steps, toner base particles as pulverized materials are obtained.

(External process)
Next, using a mixer, the obtained toner base particles and an external additive are mixed, and the external additive is attached to the toner base particles. The external additive contains at least the second resin particles. Examples of the mixer include an FM mixer (manufactured by Nippon Coke Industry Co., Ltd.). Thus, a powder (toner) of toner particles including the toner base particles and the external additive attached to the surface of the toner base particles is obtained.

[Method of mixing carrier and toner]
As a method of mixing the carrier and the toner, for example, a method of mixing the carrier and the toner while stirring using a mixer (more specifically, a ball mill, a rocking mixer (registered trademark), or the like) is exemplified. . By such a method, a developer (two-component developer) containing a carrier containing carrier particles and a toner containing toner particles is obtained. The blending amount of the toner particles with respect to 100 parts by mass of the carrier particles is preferably 1 part by mass to 20 parts by mass, and more preferably 3 parts by mass to 15 parts by mass.

  Hereinafter, examples of the present invention will be described. Note that the present invention is not limited to the scope of the embodiments.

<Preparation of resin particles S1 to S5>
108 parts by mass of ion-exchanged water (electrical conductivity: 0.05 mS / m) and hydrochloric acid were charged into a reaction vessel equipped with a thermometer, a reflux condenser, and a stirrer. Thus, a solution having a hydrogen chloride concentration of 5 × 10 ⁻⁵ mol / L was obtained. While maintaining the temperature of the solution at 20 ° C., 0.610 parts by mass of tetramethoxysilane, 3.400 parts by mass of methyltrimethoxysilane, and 3.000 parts by mass of dimethyldimethoxysilane were dropped into the reaction vessel. did. The molar ratio of the dropped alkoxysilane was tetramethoxysilane: methyltrimethoxysilane: dimethyldimethoxysilane = 0.16: 1: 1. The contents of the reaction vessel were then stirred for 4 hours (rotation speed: 50 rpm). While the contents of the reaction vessel were being stirred, a hydrolysis reaction occurred in the reaction vessel. Thus, a silanol solution was obtained.

  While maintaining the temperature of the obtained silanol solution at 5 ° C., the silanol solution was stirred (rotation speed: 50 rpm). Thereafter, an aqueous ammonia solution (concentration: 1% by mass) was dropped into the silanol solution so that the amount of ammonia added was 0.272 parts by mass. Thereafter, the contents of the reaction vessel were stirred for 4 hours. Thus, resin particles composed of a silicone resin (more specifically, a methyl silicone resin) were obtained.

  After drying the obtained resin particles (resin particles made of silicone resin), the powder of the dried resin particles is classified using an air classifier (“Elbow Jet EJ-LABO” manufactured by Nippon Steel Mining Co., Ltd.). did. At this time, the powder of the resin particles was divided into five groups having different particle diameters by changing at least one of the air volume and the edge angle of the classification edge in the air classifier. Thereafter, each of the five types of powders divided into groups was sieved to remove aggregates from each of the five types of powders. Thus, a powder of the resin particles S1 having a number-average primary particle diameter of 110 nm, a powder of the resin particles S2 having a number-average primary particle diameter of 40 nm, a powder of the resin particles S3 having a number-average primary particle diameter of 200 nm, and a number-average primary particle A powder of resin particles S4 having a particle diameter of 20 nm and a powder of resin particles S5 having a number average primary particle diameter of 220 nm were obtained. In addition, the number average primary particle diameter of the obtained resin particles S1 to S5 is the same result when the carrier particles are separated from the carrier particles after the carrier particles are prepared by the method described below and measured using the powder of the resin particles as a measurement target. was gotten.

<Preparation of carrier>
Hereinafter, a method for producing the carriers CA-1 to CA-9 and CB-1 to CB-5 will be described.

[Preparation of Carrier CA-1]
(Process of preparing carrier core)
40 parts by mass of MnO-containing particles in terms of MnO (median volume diameter (D ₅₀ ): 0.9 μm) and 10 parts by mass of MgO in terms of MgO (median volume diameter (D ₅₀ ): 0.6 μm) If, Fe ₂ O ₃ in terms of 50 parts by weight of Fe ₂ O ₃ containing particles (volume median diameter (D _50): 0.8 [mu] m) and, and water were mixed to obtain a mixture. Then, using a wet ball mill, the raw material in the mixture (for details, MnO-containing particles, MgO-containing particles and Fe ₂ O ₃ containing particles) was pulverized over 2 hours. Then, the mixture containing the crushed raw materials was dried and granulated with a spray drier. Thereafter, the dried granules were fired at a temperature of 1000 ° C. for 5 hours to obtain a carrier core (a manganese-containing ferrite core). The resulting carrier core had a volume median diameter (D ₅₀ ) of 40 μm and a saturation magnetization of 65 A · m ² / kg under an applied magnetic field of 3000 (10 ³ / 4π · A / m).

(Coating layer forming step)
100 parts by mass of a thermosetting silicone resin solution (“SR2400” manufactured by Toray Dow Corning Co., Ltd., resin: methyl silicone resin, solvent: toluene) in terms of solid content, 500 parts by mass of toluene, and 100 parts by mass of tetrafluorocarbon An ethylene-hexafluoropropylene copolymer (FEP) and 2 parts by mass of carbon black ("MA100" manufactured by Mitsubishi Chemical Corporation) were mixed to obtain a coating layer forming solution.

  Next, the carrier core (a manganese-containing ferrite core prepared by the above-described procedure) was charged into a fluid coating apparatus (“Multiplex MP-01” manufactured by Powrex Co., Ltd.) to flow the carrier core. Then, using a fluid coating apparatus, 4 parts by mass of the coating layer forming solution (the coating layer forming solution obtained by the above-described procedure) is sprayed onto 100 parts by mass of the flowing carrier core in terms of solid content. Then, a coating film was formed on the surface of the carrier core. Next, 0.03 parts by mass of the resin particles S1 were charged into the above-mentioned fluid coating apparatus with respect to 100 parts by mass of the carrier core, and the resin particles S1 were attached to a coating film formed on the surface of the carrier core. Next, the fluidized bed in the fluidized coating apparatus was subjected to a heat treatment at a temperature of 270 ° C. for 2 hours to cure the coating film. As a result, a carrier CA-1 which was a powder of carrier particles was obtained. The carrier particles contained in the carrier CA-1 adhere to the carrier core, a coat layer covering the entire surface of the carrier core (specifically, a coat layer composed of methyl silicone resin, FEP, and carbon black), and adhere to the coat layer. Resin particles S1. In the carrier CA-1, the mass of the resin particles S1 was 0.03 parts by mass with respect to 100 parts by mass of the carrier core. In the carrier CA-1, the mass of the coat layer was 4 parts by mass with respect to 100 parts by mass of the carrier core.

[Preparation of Carriers CA-2 to CA-9 and CB-1 to CB-5]
The same method as in the preparation of the carrier CA-1 except that the type of the resin particles to be attached to the coating film formed on the surface of the carrier core and the amount of the resin particles to be supplied to the fluidized coating apparatus were as shown in Table 1. To prepare carriers CA-2 to CA-9 and CB-1 to CB-4, respectively. Also, instead of 0.03 parts by mass of the resin particles S1, 0.03 parts by mass of non-crosslinked styrene-acrylic acid-based resin particles ("Finesphere (registered trademark) FS-102" manufactured by Nippon Paint Industrial Coatings Co., Ltd.) The carrier CB-5 was produced in the same manner as in the production of the carrier CA-1, except that the number average primary particle diameter was 100 nm. In addition, the input amount of the resin particles in Table 1 is the number of parts by mass with respect to 100 parts by mass of the carrier core. Further, in each of the carriers CA-2 to CA-9 and CB-1 to CB-5, the mass of the resin particles with respect to 100 parts by mass of the carrier core was the same value as the amount of the resin particles shown in Table 1. .

<Method of measuring burial ratio>
In the carriers CA-1 to CA-9, the resin particles included a buried portion buried in the surface of the coat layer and a protruding portion projecting outward in the thickness direction of the coat layer. The burying ratio of the carriers CA-1 to CA-9 was measured by the method described below. First, after dispersing a sample (any of carriers CA-1 to CA-9) in a visible light curable resin ("Aronix (registered trademark) D-800" manufactured by Toagosei Co., Ltd.), it is irradiated with visible light. The resin was cured to obtain a cured product. Thereafter, a knife for making ultra-thin sections (“Sumi Knife (registered trademark)” manufactured by Sumitomo Electric Industries, Ltd .: a diamond knife with a blade width of 2 mm and a blade angle of 45 °) and an ultramicrotome (“EM UC6” manufactured by Leica Microsystems, Inc.) Was used to cut a cured product at a cutting speed of 0.3 mm / sec to produce a 150 nm thick flake. The obtained flakes were exposed to a vapor of an aqueous ruthenium tetroxide solution for 10 minutes on a copper mesh to carry out Ru staining. Subsequently, the cross section of the stained slice sample was photographed using a transmission electron microscope (TEM) (“H-7100FA” manufactured by Hitachi High-Technologies Corporation).

The TEM image (cross-sectional image of the carrier particles) obtained as described above was analyzed using image analysis software ("WinROOF" manufactured by Mitani Corporation). Specifically, in the obtained TEM image, ten carrier particles were randomly selected. Then, in each of the selected carrier particles, one resin particle is randomly selected, and the maximum length of the buried portion in the thickness direction of the coat layer is measured for the selected resin particle using a measurement tool of image analysis software. and the L ^a, was measured and the maximum length L ^B of the protruding portions in the thickness direction of the coating layer. Next, for each of the selected carrier particles, the burial ratio, that is, L ^A / (L ^A + L ^B ) was calculated. Then, the arithmetic average of the obtained ten burial ratios was used as the evaluation value of the sample (carrier).

  The burial ratio of each of the carriers CA-1 to CA-9 was 0.1 or more and 0.5 or less.

<Preparation of toner>
Hereinafter, a method for producing the toners T1 to T6 will be described.

[Preparation of Toner T1]
(Preparation process of toner base particles)
Using an FM mixer (“FM-20B” manufactured by Nippon Coke Industry Co., Ltd.), 100 parts by mass of a binder resin (“XPE258” manufactured by Mitsui Chemicals, Inc., component: polyester resin) and 9 parts by mass of a release agent (“Nissan Elektor (registered trademark) WEP-9” manufactured by NOF Corporation, component: ester wax), 9 parts by mass of a coloring agent (“MA100” manufactured by Mitsubishi Chemical Corporation, component: carbon black), and 1 Parts by mass of a charge control agent ("BONTRON (registered trademark) P-51", manufactured by Orient Chemical Co., Ltd., component: quaternary ammonium salt) were mixed for 4 minutes at a rotation speed of 2000 rpm. Using a twin screw extruder (“PCM-30” manufactured by Ikegai Co., Ltd.), the obtained mixture was melted under the conditions of a material supply speed of 100 g / min, a shaft rotation speed of 150 rpm, and a melt kneading temperature (cylinder temperature) of 100 ° C. Kneaded. Thereafter, the obtained melt-kneaded product was cooled until its temperature reached 25 ° C.

Subsequently, the cooled melt-kneaded material was roughly pulverized using a pulverizer (“Rotoplex (registered trademark)” manufactured by Hosokawa Micron Corporation). Subsequently, the obtained coarsely pulverized product was finely pulverized using a pulverizer (“Turbomill RS” manufactured by Freund Turbo Co., Ltd.). Subsequently, the obtained finely pulverized product was classified using an air classifier (“Elbow Jet EJ-LABO” manufactured by Nippon Steel Mining Co., Ltd.). As a result, toner base particles having a volume median diameter (D ₅₀ ) of 6.7 μm were obtained.

(External process)
100 parts by mass of toner base particles (toner base particles obtained by the above-described procedure), and 1.0 part by mass of silica particles ("AEROSIL (registered trademark) REA90" manufactured by Nippon Aerosil Co., Ltd.), positively charged with a surface treatment agent A silica mixer having properties, 1.0 part by mass of conductive titanium oxide particles (“EC-100” manufactured by Titanium Industry Co., Ltd.), and 1.0 part by mass of resin particles S1 are mixed with an FM mixer ( The mixture was mixed for 5 minutes at a rotation speed of 2000 rpm and a jacket temperature of 20 ° C. using “FM-10B” manufactured by Nippon Coke Industry Co., Ltd.). Thus, external additives (silica particles, conductive titanium oxide particles, and resin particles S1) were attached to the surfaces of the toner base particles. Subsequently, the obtained powder was sieved using a 200-mesh (mesh opening: 75 μm) sieve. As a result, a positively chargeable toner T1 was obtained.

[Preparation of Toners T2 to T6]
Toners T2 to T5 were produced in the same manner as in the production of toner T1, except that the types of resin particles used in the external addition step were as shown in Table 2. When preparing the toners T2 to T5, the amount of the resin particles charged into the FM mixer was 1.0 part by mass with respect to 100 parts by mass of the toner base particles. In addition, in the external addition step, instead of 1.0 parts by mass of the resin particles S1, 1.0 parts by mass of non-crosslinked styrene-acrylic acid-based resin particles ("Fine Sphere (registered)" manufactured by Nippon Paint Industrial Coatings Co., Ltd. (Trademark) FS-102 ", number average primary particle diameter: 100 nm), except that toner T6 was produced in the same manner as in the production of toner T1. Each of the obtained toners T2 to T6 was a positively chargeable toner.

<Preparation of developer>
[Preparation of developer DA-1]
100 parts by mass of the carrier CA-1 and 8 parts by mass of the toner T1 are mixed using a powder mixer ("Rocking Mixer (registered trademark)" manufactured by Aichi Electric Co., Ltd., mixing method: container rotation swinging method). The mixture was mixed for 30 minutes to prepare a developer DA-1.

[Preparation of Developers DA-2 to DA-9 and DB-1 to DB-6]
Developers DA-2 to DA-9 and DB are prepared in the same manner as in the preparation of developer DA-1, except that the carrier and toner used for mixing with the powder mixer are as shown in Table 3 described below. -1 to DB-6 were prepared respectively. When preparing the developers DA-2 to DA-9 and DB-1 to DB-6, the used amount (mass) of the toner to 100 parts by mass of the carrier was 8 parts by mass.

<Evaluation method>
[Measurement of initial charge amount]
After preparing the developer (any of the developers DA-1 to DA-9 and DB-1 to DB-6) by the method described above, the developer is applied for 24 hours in an environment of a temperature of 25 ° C. and a humidity of 65% RH. Was left still. Thereafter, in an environment of a temperature of 25 ° C. and a humidity of 65% RH, the charge amount (unit: μC / g) of the toner contained in the developer was measured using a Q / m meter (“MODEL 210HS” manufactured by Trek). . Hereinafter, the measured charge amount is referred to as “initial charge amount E1” (or simply “E1”).

  When the initial charge amount E1 was 20 μC / g or more and 40 μC / g or less, it was evaluated that “a toner charge amount suitable for image formation was secured”. On the other hand, when the initial charge amount E1 was less than 20 μC / g and when the initial charge amount E1 exceeded 40 μC / g, it was evaluated that “the toner charge amount suitable for image formation could not be secured”.

[Measurement of charge amount after continuous printing]
A printer (“ECOSYS (registered trademark) FS-C5250DN” manufactured by Kyocera Document Solutions Inc.) was used as the evaluation machine. The developer (any of the developers DA-1 to DA-9 and DB-1 to DB-6) prepared by the above-described method was charged into a black developing device of an evaluation machine, and used in the preparation of the developer. A toner of the same type as the toner (any one of toners T1 to T6) was charged into a black toner container of the evaluation machine.

  Then, under an environment of a temperature of 25 ° C. and a humidity of 65% RH, 100,000 sheets of character images (printing rate: 4%) were continuously printed on printing paper (A4 size). Next, after taking out the developer from the black developing device of the evaluator, the charge amount (unit: μC / g) of the toner contained in the developer is Q / m under an environment of a temperature of 25 ° C. and a humidity of 65% RH. It measured using the meter ("MODEL210HS" by Trek). Hereinafter, the charge amount measured here is referred to as “charge amount E2 after continuous printing” (or simply “E2”).

[Calculation of charge variation rate]
From the initial charge amount E1 obtained as described above and the charge amount E2 after continuous printing, a charge amount variation rate (unit:%) was obtained based on the following equation. In the following equation, | E1-E2 | represents the absolute value of the difference between E1 and E2.
Charge variation rate = 100 × | E1-E2 | / E1

  When the charge amount variation rate was 20% or less, it was evaluated that "the change in the charge amount of the toner before and after printing a large number of sheets could be suppressed". On the other hand, when the charge amount variation rate exceeds 20%, it was evaluated that “the change in the charge amount of the toner before and after printing a large number of sheets could not be suppressed”.

  For the developers DA-1 to DA-9 and DB-1 to DB-6, the type of carrier and toner used, E1, E2, and the charge amount variation rate are shown in Table 3, respectively.

  In the developers DA-1 to DA-9, the carrier particles include a carrier core, a coat layer covering the surface of the carrier core, and first resin particles (resin particles made of a silicone resin) attached to the coat layer. Was. In the carrier particles included in each of the developers DA-1 to DA-9, the first resin particles have a buried portion embedded in the surface of the coat layer and a projecting portion projecting outward in the thickness direction of the coat layer. Was included. In the developers DA-1 to DA-9, the mass of the first resin particles was 0.03 parts by mass or more and 0.15 parts by mass or less based on 100 parts by mass of the carrier core. In the developers DA-1 to DA-9, the toner particles included toner base particles containing a binder resin and external additives attached to the surfaces of the toner base particles. In the toner particles contained in each of the developers DA-1 to DA-9, the external additive contained the second resin particles (resin particles made of silicone resin).

  As shown in Table 3, in the developers DA-1 to DA-9, E1 was 20 μC / g or more and 40 μC / g or less. Therefore, the developer DA-1 to DA-9 could secure a charge amount of the toner suitable for image formation. In the developers DA-1 to DA-9, the charge amount variation rate was 20% or less. Therefore, the developers DA-1 to DA-9 were able to suppress the change in the charge amount of the toner before and after printing a large number of sheets.

  In the developers DB-1 to DB-4, the carrier particles include a carrier core, a coat layer covering the surface of the carrier core, and first resin particles (resin particles made of a silicone resin) attached to the coat layer. Was. However, in the developers DB-1 and DB-4, the mass of the first resin particles was less than 0.03 parts by mass with respect to 100 parts by mass of the carrier core. Further, in the developers DB-2 and DB-3, the mass of the first resin particles exceeded 0.15 parts by mass with respect to 100 parts by mass of the carrier core.

  In the developer DB-5, the carrier particles had a carrier core, a coat layer covering the surface of the carrier core, and resin particles attached to the coat layer. However, in the carrier particles contained in the developer DB-5, the resin particles attached to the coat layer did not contain a silicone resin.

  In the developer DB-6, the carrier particles were provided with a carrier core, a coat layer covering the surface of the carrier core, and resin particles attached to the coat layer. However, in the developer DB-6, the carrier particles are resin particles including a buried portion embedded in the surface of the coat layer and a protruding portion protruding outward in the thickness direction of the coat layer. There were no particles. When measuring the charge amount E2 after the continuous printing described above for the developer DB-6, the carrier particles contained in the developer DB-6 after the character image is continuously printed on printing paper for 100,000 sheets are the toner particles. Resin particles transferred from the particles (resin particles made of silicone resin used as external additive particles, hereinafter referred to as “migrated resin particles”) were included. However, the transferred resin particles adhered to the surface of the coat layer without being embedded. Therefore, the transfer resin particles did not have a buried portion. Further, the mass of the transferred resin particles was less than 0.03 parts by mass based on 100 parts by mass of the carrier core.

  As shown in Table 3, in the developers DB-2, DB-3 and DB-6, E1 was less than 20 μC / g. Therefore, the developers DB-2, DB-3, and DB-6 could not secure a charge amount of the toner suitable for image formation. In the developer DB-4, E1 was more than 40 μC / g. Therefore, the developer DB-4 could not secure a charge amount of the toner suitable for image formation.

  As shown in Table 3, in the developers DB-1 and DB-4 to DB-6, the charge amount variation rate exceeded 20%. Therefore, the developers DB-1 and DB-4 to DB-6 have not been able to suppress the fluctuation of the charge amount of the toner before and after printing a large number of sheets.

  From the above results, it was shown that according to the present invention, it is possible to suppress the fluctuation of the charge amount of the toner before and after printing a large number of sheets while securing the charge amount of the toner suitable for image formation.

  The two-component developer according to the present invention can be used for forming an image in, for example, a copying machine, a printer, or a multifunction peripheral.

DESCRIPTION OF SYMBOLS 10 Carrier particle 11 Carrier core 12 Coat layer 13 1st resin particle 20 Toner particle 21 Toner base particle 22 2nd resin particle 100 Developer (2 component developer)

Claims (6)

A two-component developer containing a carrier containing carrier particles and a toner containing toner particles,
The carrier particles include a carrier core, a coat layer covering a surface of the carrier core, and first resin particles attached to the coat layer,
The first resin particles include a buried portion embedded in a surface of the coat layer, and a protruding portion that protrudes outward in a thickness direction of the coat layer,
The mass of the first resin particles is 0.03 parts by mass or more and 0.15 parts by mass or less based on 100 parts by mass of the carrier core.
The toner particles include toner base particles including a binder resin, and an external additive attached to the surface of the toner base particles,
The external additive includes second resin particles,
The two-component developer, wherein the first resin particles and the second resin particles each include a silicone resin.   The two-component developer according to claim 1, wherein the coat layer includes a silicone resin.   The two-component developer according to claim 2, wherein the coat layer further includes a fluororesin.   The two-component developer according to any one of claims 1 to 3, wherein the mass of the coat layer is 2 parts by mass or more and 10 parts by mass or less based on 100 parts by mass of the carrier core.   The two-component development according to any one of claims 1 to 4, wherein the mass of the second resin particles is 0.5 parts by mass or more and 1.5 parts by mass or less based on 100 parts by mass of the toner base particles. Agent. In the cross section of the first resin particles, the maximum length of the immersed part in the thickness direction of the coating layer is L ^A, when the maximum length of the projecting portion in the thickness direction of the coating layer was L ^B satisfy the relationship of ^{0.1 ≦ L a / (L a} + L B) ≦ 0.5, 2 -component developer according to any one of claims 1 to 5.

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