Two-component developer and image forming method

Abstract

To provide a two-component developer that has near infrared permeability, has high image density, and is excellent in resistance of electrostatic propensity against environmental conditions, and an image forming method.SOLUTION: In a two-component developer of the present invention, a toner base particle contains a coloring agent. The coloring agent contains a pigment P1 and a pigment P2. When the pigments P1 and P2 are each dispersed in methyl ethyl ketone, an absorption maximum wavelength λmax of the pigment P1 is within a range of 400 nm or more and less than 600 nm, and λmax of the pigment P2 is within a range of 600 nm or more and 700 nm or less. An external additive contains titanium oxide. The content of the titanium oxide is 0.01 mass% or more and less than 1.00 mass% based on the total mass of the toner base particle. The content of iron element in a surface of a carrier measured by X-ray photoelectron spectroscopy satisfies a specific formula.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a two-component developer and an image forming method, and more particularly to a two-component developer and an image forming method that have near-infrared transmittance, high image density, and excellent environmental condition resistance of chargeability. [Background technology]

[0002] In recent years, two-component developers consisting of a toner for developing electrostatic images (hereinafter simply referred to as "toner") and a carrier for developing electrostatic images (hereinafter simply referred to as "carrier") made of magnetic powder have become mainstream in electrophotographic copiers and printers because of their advantage in high-speed development.

[0003] In particular, with regard to toner, organic pigments of different colors are incorporated into one toner base particle (toner base particles will be described in detail later) to develop a toner that absorbs light in a wide wavelength range, and in particular, toner that has the property of absorbing light in the visible light range but transmitting (hard to absorb) light in the near-infrared range is attracting attention. By using such a toner, it is possible to form an image that appears black but is detected as transparent when a detector sensitive only to near-infrared light is used, and it is expected that by making use of this property and giving transparency to near-infrared light only to a portion of the toner, it will be possible to form an image in which information that cannot be recognized by the human eye is embedded.

[0004] For example, most of the black toners that absorb visible light, as disclosed in Patent Documents 1 and 2, also absorb near-infrared light, and therefore do not have the above-mentioned characteristics.

[0005] Furthermore, in the case of a toner in which pigments of different color tones as described above are internally added to one toner base particle, when titanium oxide is used as an external additive, titanium oxide having a high specific gravity is likely to migrate from the toner under high temperature and high humidity environmental conditions, and the environmental condition resistance of the chargeability is likely to become insufficient. Therefore, there has been a demand for further improvement in the environmental condition resistance of the chargeability. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 5-297635 [Patent Document 2] JP 2009-79096 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above problems and circumstances, and the problem to be solved by the present invention is to provide a two-component developer and an image forming method that have near-infrared transmittance, high image density, and excellent environmental condition resistance of charging properties. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present inventors have investigated the causes of the above-mentioned problems, and as a result, have found that in a two-component developer containing a toner for developing electrostatic images, which includes toner particles having a toner base particle and an external additive, and a carrier, by containing a colorant that absorbs light in the visible light region in the toner base particle, containing titanium oxide in the external additive, and setting the iron element content of the carrier surface within a specific range, it is possible to provide a two-component developer and an image forming method that have near-infrared transmittance, high image density, and excellent environmental condition resistance of charging properties, and have arrived at the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0009] 1. A two-component developer including a toner for developing electrostatic images, the toner particles including a toner base particle and an external additive, and a carrier, the toner base particle containing a colorant, the colorant containing a pigment P1 and a pigment P2, the pigments P1 and P2 each having a maximum absorption wavelength λmax of 400 nm or more and less than 600 nm when dispersed in methyl ethyl ketone, and the pigment P1 having a maximum absorption wavelength λmax of 600 nm or more and 700 nm or less when dispersed in methyl ethyl ketone, the pigment P1 contains pigments P1-1, P1-2, and P1-3, and when the pigments P1-1, P1-2, and P1-3 are each dispersed in methyl ethyl ketone, the maximum absorption wavelength λmax of the pigment P1-1 is within a range of 400 nm or more and less than 460 nm, the maximum absorption wavelength λmax of the pigment P1-2 is within a range of 460 nm or more and 530 nm or less, and the maximum absorption wavelength λmax of the pigment P1-3 is within a range of more than 530 nm and less than 600 nm;The external additive contains titanium oxide, and the content of the titanium oxide is 0.01% by mass or more and less than 1.00% by mass with respect to the total mass of the toner base particles, and the iron element content (atomic %) of the surface of the carrier measured by X-ray photoelectron spectroscopy satisfies the following formula (1): Equation (1) 2≦{A Fe / (A C +A O +A Fe )}×100≦20 (However, A Fe , A C and A O represent the contents (atomic %) of Fe, C and O per unit area of ​​the carrier surface, respectively. A two-component developer comprising:

[0011] 2 The pigment P1-2 includes at least one pigment selected from the group consisting of CI Pigment Brown 23, CI Pigment Brown 25, CI Pigment Brown 41, and CI Pigment Red 38. 1 Item 2. The two-component developer according to item 1.

[0012] 3 Item 1, characterized in that the pigment P2 comprises at least one pigment selected from the group consisting of CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Blue 15:5, CI Pigment Blue 15:6 and CI Pigment Blue 16. or No. In item 2 The two-component developer described herein.

[0014] 4.The pigment P1-3 is CIPigment Orange 34, CIPigment Orange 36, CIPigment Orange 38, CIPigment Orange 43, CIPigment Orange 62, CIPigment Orange 68, CIPigment Orange 70, CIPigment Orange 72, CIPigment Orange 74, CIPigment Red 31, CIPigment Red 48:4, CIPigment Red. 57:1, CIPigment Red 122, CIPigment Red 146, CIPigment Red 147, CIPigment Red 150, CIPigment Red 184, CIPigment Red 238, CIPigment Red 242, CIPigment Red 254, CIPigment Red 269, CIPigment Violet 19, CIPigment Violet 23 and CIPigment Violet 32, characterized in that it contains at least one pigment selected from the group consisting of 1 term Any one of paragraphs 1 to 3 The two-component developer according to claim 1.

[0016] 5 The pigment P1-1 is characterized in that it contains at least one pigment selected from the group consisting of CI Pigment Yellow 74, CI Pigment Yellow 120, CI Pigment Yellow 139, CI Pigment Yellow 151, CI Pigment Yellow 155, CI Pigment Yellow 180, CI Pigment Yellow 181, CI Pigment Yellow 185, CI Pigment Yellow 213, CI Pigment Green 7 and CI Pigment Green 36. 1 term Any one of paragraphs 1 to 4 The two-component developer according to claim 1.

[0017] 6 The toner base particles contain a crystalline polyester. 5 Item 1. The two-component developer according to any one of items 1 to 9.

[0018] 7 The carrier has a resin layer at least on the surface of the core material, and the resin contained in the resin layer contains a resin having a structural unit derived from an alicyclic (meth)acrylic acid ester. 6 Item 1. The two-component developer according to any one of items 1 to 9.

[0019] 8 The content of the structural unit derived from the alicyclic (meth)acrylic acid ester in the resin contained in the resin layer is 50% by mass or more with respect to the total mass of the resin contained in the resin layer. 7 Item 2. The two-component developer according to item 1.

[0020] 9 An image forming method using a two-component developer, comprising: 8 3. An image forming method comprising the steps of: using the two-component developer according to any one of claims 1 to 2, adhering the electrostatic image developing toner contained in the two-component developer to a recording medium; and fixing the adhered electrostatic image developing toner to the recording medium. Effect of the Invention

[0021] According to the above-mentioned means of the present invention, it is possible to provide a two-component developer and an image forming method which have near-infrared transmittance, high image density, and excellent environmental condition resistance of chargeability.

[0022] Although the mechanism by which the effects of the present invention are manifested or the mechanism by which the effects of the present invention are acted upon has not been clearly understood, it is speculated as follows.

[0023] In this specification, the term "visible light region" refers to a region in which the wavelength of light (electromagnetic waves) is 400 nm or more and 800 nm or less, and the term "near-infrared region" refers to a region in which the wavelength of light (electromagnetic waves) is more than 800 nm and 2500 nm or less.

[0024] In recent years, the development of functional black toners has progressed, and among them, black toners that have a function of transmitting near-infrared rays have attracted attention. It is expected that the use of such toners will enable the formation of images and the like in which information that cannot be recognized by the human eye is embedded.

[0025] Usually, black toners use black colorants. However, conventionally known black colorants absorb not only visible light but also near infrared light, and therefore cannot be used for the present purpose. Another method for producing black toner is to combine multiple colorants having a maximum absorption wavelength in the visible light region to absorb light in the entire visible light region. In particular, the present toner can be obtained by using a colorant having a maximum absorption wavelength in the visible light region and not absorbing (transmitting) light in the near infrared region.

[0026] In addition, by using a large amount of a colorant having a maximum absorption wavelength in the visible light region, the visible light absorption is improved, and the color development of black is improved. However, when the pigment used as the colorant is highly loaded in the toner, the surface of the toner base particles (toner base particles will be described later) becomes relatively hard, so that the external additives are easily removed and the charge amount is easily reduced over a long period of use.

[0027] By using titanium oxide as an external additive for such a toner, the fluidity of the toner can be improved. However, titanium oxide is generally used as a white pigment, and the inclusion of titanium oxide reduces the black color development (image density) of the toner. Therefore, the content of titanium oxide is limited to a level that maintains sufficient color development (image density).

[0028] In addition, titanium oxide has low electrical resistance, so that adding it to the surface of the toner base particle can reduce the resistance of the toner, but as mentioned above, the content of titanium oxide is limited, so the resistance cannot be sufficiently reduced, and the toner still has high resistance. In a two-component developer consisting of a toner and a carrier, it is preferable that the carrier has low resistance in consideration of the developability. In addition, during long-term use, the external additive separated from the toner may adhere to the carrier, causing the resistance of the carrier to increase. Therefore, the surface of the carrier needs to be low-resistance and configured to prevent the external additive from adhering.

[0029] Usually, the carrier has a shape in which the surface of the core particles made of a magnetic material is coated with a resin. If the core particles are sufficiently coated with the resin, the toner does not scatter and a stable image density can be obtained. However, if the core particles are completely coated with the resin, the core particles made of a magnetic material are not exposed, and the resistance of the carrier becomes high. Therefore, the carrier needs to be coated with the resin so that the core particles are appropriately exposed.

[0030] The above formula (1) represents the relationship of the iron element content on the carrier surface. The main atoms on the carrier surface are carbon, oxygen, and iron. Carbon is mainly derived from the resin. In the present invention, an iron oxide-based material is used as the carrier core material, so iron is mainly derived from the core material. Formula (1) represents the proportion of iron among the main atoms (carbon, oxygen, and iron) on the carrier surface, and by setting this proportion within a specific range, the core material particles are appropriately exposed on the carrier surface.

[0031] In addition, by providing the surface shape of the carrier core particles with moderate irregularities, it becomes difficult to uniformly coat the resin, and the core particles tend to be appropriately exposed on the carrier surface. Furthermore, by providing such a shape, it becomes difficult for external additives that have separated from the toner to adhere to the carrier, and the desired carrier can be obtained. [Brief description of the drawings]

[0032] [Figure 1] FIG. 1 is a schematic diagram showing an example of an image forming apparatus 100 according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] The two-component developer of the present invention is a two-component developer including a toner for developing electrostatic images, the toner particles having a toner base particle and an external additive, and a carrier, the toner base particle containing a colorant, the colorant containing a pigment P1 and a pigment P2, the pigments P1 and P2 each having a maximum absorption wavelength λmax of 400 nm or more and less than 600 nm when dispersed in methyl ethyl ketone for the pigment P1, and having a maximum absorption wavelength λmax of 600 nm or more and less than 700 nm for the pigment P2, the external additive containing titanium oxide, the content of the titanium oxide being 0.01 mass % or more and less than 1.00 mass % with respect to the total mass of the toner base particle, and the iron element content (atomic %) of the surface of the carrier measured by X-ray photoelectron spectroscopy (XPS) satisfies the following formula (1). Equation (1) 2≦{A Fe / (A C +A O +A Fe )}×100≦20 (However, A Fe , A C and A O represent the contents (atomic %) of Fe, C and O per unit area of ​​the carrier surface, respectively. This feature is a technical feature common to or corresponding to the following embodiments.

[0034] In an embodiment of the present invention, from the viewpoint of black color development, it is preferable that pigment P1 contains pigment P1-2, and that the maximum absorption wavelength λmax of pigment P1-2 when dispersed in methyl ethyl ketone is in the range of 460 nm or more and 530 nm or less, and further it is preferable that pigment P1-2 contains at least one pigment selected from the group consisting of CI Pigment Brown 23, CI Pigment Brown 25, CI Pigment Brown 41, and CI Pigment Red 38.

[0035] From the viewpoint of black color development, it is preferable that the pigment P2 contains at least one pigment selected from the group consisting of the above-mentioned pigments such as CI Pigment Blue 15 and CI Pigment Blue 15:1.

[0036] From the viewpoint of black color development, it is preferable that pigment P1 contains pigment P1-3, and that pigment P1-3 has a maximum absorption wavelength λmax (nm) of more than 530 nm and less than 600 nm when dispersed in methyl ethyl ketone, and further it is preferable that pigment P1-3 contains at least one pigment selected from the group consisting of the above-mentioned pigments such as CI Pigment Orange 34 and CI Pigment Orange 36.

[0037] From the viewpoint of black color development, it is preferable that pigment P1 contains pigment P1-1, and that the maximum absorption wavelength λmax (nm) of pigment P1-1 when dispersed in methyl ethyl ketone is in the range of 400 nm or more and less than 460 nm, and further, it is preferable that pigment P1-1 contains at least one pigment selected from the group consisting of the above-mentioned pigments such as CI Pigment Yellow 74 and CI Pigment Yellow 120.

[0038] From the viewpoint of low-temperature fixability, it is preferable that the toner base particles contain a crystalline polyester.

[0039] From the viewpoint of environmental condition resistance of electrostatic charge, it is preferable that the carrier has a resin layer at least on the surface of the core material, and that the resin contained in the resin layer contains a resin having a structural unit derived from an alicyclic (meth)acrylic acid ester, and further, it is preferable that the content of the structural unit derived from an alicyclic (meth)acrylic acid ester in the resin contained in the resin layer is 50 mass% or more relative to the total mass of the resin contained in the resin layer.

[0040] The image forming method of the present invention is characterized by comprising a step of adhering the electrostatic image developing toner contained in the two-component developer of the present invention to a recording medium, and a step of fixing the adhered electrostatic image developing toner to the recording medium.

[0041] The present invention, its components, and embodiments for carrying out the present invention will be described in detail below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after the symbol "to" are included as the lower limit and upper limit.

[0042] <<Outline of the two-component developer of the present invention>> The two-component developer of the present invention is a two-component developer including a toner for developing electrostatic images, the toner particles having a toner base particle and an external additive, and a carrier, the toner base particle containing a colorant, the colorant containing a pigment P1 and a pigment P2, the pigments P1 and P2 each having a maximum absorption wavelength λmax of 400 nm or more and less than 600 nm when dispersed in methyl ethyl ketone for the pigment P1, and having a maximum absorption wavelength λmax of 600 nm or more and less than 700 nm for the pigment P2, the external additive containing titanium oxide, the content of the titanium oxide being 0.01 mass % or more and less than 1.00 mass % with respect to the total mass of the toner base particle, and the iron element content (atomic %) of the surface of the carrier measured by X-ray photoelectron spectroscopy (XPS) satisfies the following formula (1). Equation (1) 2≦{A Fe / (A C +A O +A Fe )}×100≦20 (However, AFe , A C and A O represent the contents (atomic %) of Fe, C and O per unit area of ​​the carrier surface, respectively.

[0043] The toner according to the present invention is a black toner having a function of transmitting near-infrared rays. Since the above toner is highly packed with pigment, the charge amount is likely to decrease under high temperature and high humidity environmental conditions. However, by using the toner in combination with the carrier according to the present invention as a two-component developer, it is possible to obtain chargeability resistant to environmental conditions.

[0044] The toner for developing electrostatic images according to the present invention may also be simply referred to as “toner.” The toner of the present invention includes toner particles having toner base particles and an external additive attached to the surfaces of the toner base particles. In this specification, "toner base particles" are those that constitute the base of "toner particles." The "toner base particles" according to the present invention contain at least a colorant, and may contain other components such as a release agent (wax) and a charge control agent as necessary. The "toner base particles" are called "toner particles" when an external additive is added. And, "toner" refers to an aggregate of toner particles.

[0045] <Toner for developing electrostatic images> [1 Toner base particles] The toner base particles according to the present invention contain a colorant and preferably further contain a binder resin.

[0046] The toner base particles preferably have a volume-based average particle diameter in the range of 5 to 8 μm, more preferably in the range of 5.5 to 7 μm. By making the volume-based average particle diameter of the toner base particles 5 μm or more, two or more pigments can be sufficiently incorporated into the toner base particles to improve color development and to increase the transfer efficiency of the toner. In addition, by making the volume-based average particle diameter of the toner base particles 8 μm or less, the resolution of the formed image can be further improved.

[0047] The volume-based average particle size of the toner base particles can be measured using a measuring device that is a particle size distribution measuring device (Coulter Multisizer 3, manufactured by Beckman Coulter, Inc.) connected to a computer system equipped with data processing software Software V3.51. Specifically, 0.02 g of a sample (toner base particles) is added to 20 mL of a surfactant solution (a surfactant solution obtained by diluting, for example, a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing toner particles), and then ultrasonic dispersion treatment is performed for 1 minute to prepare a dispersion liquid of the toner base particles. This dispersion liquid is injected with a pipette into a beaker containing an electrolyte (ISOTON II, manufactured by Beckman Coulter, Inc.) in a sample stand until the concentration displayed on the measuring device is 8%. By adjusting the concentration to this level, reproducible measurement values ​​can be obtained. In the measurement device, the measurement particle count is set to 25,000 particles, the aperture diameter is set to 100 μm, the measurement range of 2 to 60 μm is divided into 256 parts to calculate the frequency value, and the volume-based average particle diameter is calculated based on this.

[0048] [1.1 Coloring agent] The toner according to the present invention contains a colorant in the toner base particles.

[0049] From the viewpoint of sufficiently absorbing light of a wider range of wavelengths in the visible light region, the colorant is a combination of pigment P1, which has a maximum absorption wavelength λmax in the short wavelength region (region of 400 nm or more and less than 600 nm) when the visible light region (400 nm to 700 nm) is divided in half, and pigment P2, which has a maximum absorption wavelength λmax in the long wavelength region (region of 600 nm or more and 700 nm or less) when the visible light region is divided in half.

[0050] In this specification, the maximum absorption wavelength λmax of a pigment is determined by mixing 0.02 parts by mass of the pigment with 100 parts by mass of methyl ethyl ketone, placing the resulting dispersion in a quartz cell for a spectrophotometer having an optical path length of 10 mm, and measuring the absorption spectrum in the wavelength range of 400 to 700 nm with the spectrophotometer.

[0051] Pigment P1 can be further divided into pigment P1-1, which has a maximum absorption wavelength λmax in the range of 400 nm or more and less than 460 nm, pigment P1-2, which has a maximum absorption wavelength λmax in the range of 460 nm or more and 530 nm or less, and pigment P1-3, which has a maximum absorption wavelength λmax in the range of more than 530 nm and less than 600 nm. From the viewpoint of being able to sufficiently absorb light of a wider wavelength range in the visible light region by combining with pigment P2, it is preferable that pigment P1 contains pigment P1-2.

[0052] From a similar viewpoint, the maximum absorption wavelength λmax of pigment P1-1 is preferably in the range of more than 410 nm and less than 450 nm, the maximum absorption wavelength λmax of pigment P1-2 is preferably in the range of 480 nm or more and 510 nm or less, the maximum absorption wavelength λmax of pigment P1-3 is preferably in the range of more than 540 nm and less than 590 nm, and the maximum absorption wavelength λmax of pigment P2 is preferably in the range of 620 nm or more and 660 nm or less.

[0053] Pigment P1-2 is a pigment having a maximum absorption wavelength λmax in the central wavelength region (460 nm or more and 530 nm or less) of the wavelength region (400 nm to 600 nm) in which pigment P1 can have a maximum absorption wavelength. By combining pigment P1-2 and pigment P2, it is possible to further increase the light absorption in the visible light region. In addition, pigment P1-2 is often a low-resistance pigment, and is less likely to cause a decrease in chargeability due to excessive charging of the toner.

[0054] From the viewpoint of being able to sufficiently absorb light of a wider range of wavelengths in the visible light region, it is preferable that the half-maximum wavelength on the long wavelength side of the absorption spectrum of pigment P1-2 is 550 nm or more.

[0055] There are no particular limitations on the pigment P1-1 so long as it has a maximum absorption wavelength within the above range, and examples thereof include monoazo pigments, disazo pigments, benzimidazoline pigments, isoindolinone pigments, isoindoline pigments, and perinone pigments. Specifically, CIPigment Yellow 1, CIPigment Yellow 3, CIPigment Yellow 12, CIPigment Yellow 13, CIPigment Yellow 14, CIPigment Yellow 16, CIPigment Yellow 17, CIPigment Yellow 73, CIPigment Yellow 74, CIPigment Yellow 81, CIPigment Yellow 83, CIPigment Yellow 87, CIPigment Yellow 97, CIPigment Yellow 111, CIPigment Yellow 120, CIPigment Yellow 126, CIPigment Yellow 127, CIPigment Yellow 128, CIPigment Yellow 139, CIPigment Yellow 151, CIPigment Yellow 154, CIPigment Yellow 155, CIPigment Yellow 173, CIPigment Yellow 174, CIPigment Yellow 175、CIPigment Yellow CI Pigment Yellow 176, CI Pigment Yellow 180, CI Pigment Yellow 181, CI Pigment Yellow 185, CI Pigment Yellow 191, CI Pigment Yellow 194, CI Pigment Yellow 196, CI Pigment Yellow 213, CI Pigment Yellow 214, CI Pigment Yellow 217, CI Pigment Green 7 and CI Pigment Green 36. These may be used alone or in combination of two or more.

[0056] Of these, CI Pigment Yellow 74, CI Pigment Yellow 120, CI Pigment Yellow 139, CI Pigment Yellow 151, CI Pigment Yellow 155, CI Pigment Yellow 180, CI Pigment Yellow 181, CI Pigment Yellow 185, CI Pigment Yellow 213, CI Pigment Green 7 and CI Pigment Green 36 are preferably used from the viewpoint of obtaining good color development and light fastness.

[0057] The pigment P1-2 is not particularly limited as long as it has a maximum absorption wavelength within the above range, and examples thereof include monoazo pigments, disazo pigments, condensed azo pigments, naphthol AS pigments, and benzimidazolone pigments.Specific examples of the pigment P1-2 include CI Pigment Brown 23, CI Pigment Brown 25, CI Pigment Brown 41, and CI Pigment Red 38.These pigments may be used alone or in combination of two or more.In addition, these pigments are preferably used in any case from the viewpoint of obtaining good color development and light resistance.

[0058] The pigment P1-3 is not particularly limited as long as it has a maximum absorption wavelength within the above range, and examples thereof include monoazo pigments, disazo pigments, β-naphthol pigments, naphthol AS pigments, azo lake pigments, benzimidazolone pigments, anthanthrone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, perylene pigments, thioindigo pigments, triarylcarbonium pigments, and diketopyrrolopyrrole pigments. Specifically, CIPigment Orange 5, CIPigment Orange 13, CIPigment Orange 34, CIPigment Orange 36, CIPigment Orange 38, CIPigment Orange 43, CIPigment Orange 62, CIPigment Orange 68, CIPigment Orange 70, CIPigment Orange 72, CIPigment Orange 74, CIPigment Red 2, CIPigment Red 3, CIPigment Red 4, CIPigment Red 5, CIPigment Red 9, CIPigment Red 12, CIPigment Red 14, CIPigment Red 31, CIPigment Red 48:2, CIPigment Red 48:3, CIPigment Red 48:4, CIPigment Red 53:1, CIPigment Red 57:1, CIPigment Red 112, CIPigment Red 122, CIPigment Red 144, CIPigment Red 146, CIPigment Red 147, CIPigment Red 149, CIPigment Red 150, CIPigment Red 168, CIPigment Red 169, CIPigment Red 170, CIPigment Red 175, CIPigment Red 176, CIPigment Red 177, CIPigment Red 179, CIPigment Red 181, CIPigment Red 184, CIPigment Red 185, CIPigment Red 187, CIPigment Red 188, CIPigment Red 207, CIPigment Red 208, CIPigment Red 209, CIPigment Red 210, CIPigment Red 214, CIPigment Red 238, CIPigment Red 242, CIPigment Red 247, CIPigment Red 253, CIPigment Red 254, CIPigment Red 256, CIPigment Red 257, CIPigment Red 262, CIPigment Red 263, CIPigment Red 266, CIPigment Red 269, CIPigment Red 274, CIPigment Violet 19, CIPigment Violet 23, and CIPigment Violet 32. These may be used alone or in combination of two or more.

[0059] Of these, CIPigment Orange 34, CIPigment Orange 36, CIPigment Orange 38, CIPigment Orange 43, CIPigment Orange 62, CIPigment Orange 68, CIPigment Orange 70, CIPigment Orange 72, CIPigment Orange 74, CIPigment Red 31, CIPigment Red 48:4, CIPigment Red 57:1, CIPigment Red 122, CIPigment Red 146, CIPigment Red 147, CIPigment Red 150, CIPigment Red 184, CIPigment Red 238, CIPigment Red 242, CIPigment Red 254, CIPigment Red 269, CIPigment Violet 19, CIPigment Violet 23, and CIPigment Violet 32 is preferably used from the viewpoint of obtaining good color development and light resistance.

[0060] From the viewpoint of being able to sufficiently absorb light of a wider wavelength range in the visible light region, the pigment P1 preferably contains any two or more of the pigments P1-1 to P1-3, and more preferably contains all of them. Furthermore, by containing more types of pigments in the toner base particles, the charging stability is improved and the fixation to the recording medium is also improved. Furthermore, even if any pigment fades, the other pigments can cover the wavelength range of the faded pigment, so the light resistance of the formed image is also improved. And, according to the knowledge of the present inventors, the more types of pigments there are, the higher the dispersibility of the crystalline resin (particularly the crystalline polyester resin) is probably, and the better the toner fixation is.

[0061] The pigment P2 is not particularly limited as long as it has a maximum absorption wavelength within the above range, and specific examples thereof include CICI Pigment Blue 15, CICI Pigment Blue 15:1, CICI Pigment Blue 15:2, CICI Pigment Blue 15:3, CICI Pigment Blue 15:4, CICI Pigment Blue 15:5, CICI Pigment Blue 15:6, CICI Pigment Blue 16, CICI Pigment Blue 56, CICI Pigment Blue 60, CICI Pigment Blue 61, and CICI Pigment Blue 80. These may be used alone or in combination of two or more.

[0062] From the viewpoints of improving the hue, improving the electrical conductivity and light fastness, and suppressing a decrease in the transmittance of light in the near-infrared region, pigment P2 is preferably a phthalocyanine pigment, and among these, it is preferable to use CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Blue 15:5, CI Pigment Blue 15:6 or CI Pigment Blue 16.

[0063] The total content of the pigments is preferably within a range of 1 to 30% by mass, more preferably within a range of 5 to 20% by mass, and even more preferably within a range of 7 to 20% by mass, based on the total mass of the toner base particles. When the total content of the pigments is 1% by mass or more, the color development of the formed image can be improved. Furthermore, when the total content of the pigments is 30% by mass or less, a sufficient amount of binder resin can be contained in the toner base particles, so that the toner base particles become flexible, sufficient fixation of the image can be obtained, and titanium oxide is less likely to separate.

[0064] Regarding the content of each pigment, the total content of pigment P1-2 and pigment P2 is preferably within the range of 60 to 100 mass% relative to the total mass of the pigments, the content of pigment P1-1 is preferably within the range of 0 to 40 mass% relative to the total mass of the pigments, and the content of pigment P1-3 is preferably within the range of 0 to 40 mass% relative to the total mass of the pigments.

[0065] Furthermore, the content of pigment P1-2 is preferably within the range of 31 to 69 mass%, more preferably within the range of 35 to 65 mass%, and even more preferably within the range of 40 to 60 mass%, relative to the total mass of pigment P1-2 and pigment P2. The content of pigment P2 is preferably within the range of 31 to 69 mass%, more preferably within the range of 35 to 65 mass%, and even more preferably within the range of 40 to 60 mass%, relative to the total mass of pigment P1-2 and pigment P2.

[0066] Carbon black is a black colorant that absorbs light in the visible light region, but tends to reduce the transmittance of light in the near infrared region. In addition, because of its high electrical conductivity, it tends to make the chargeability of the toner unstable, or to reduce the dielectric loss tangent (transferability) because it cannot retain charge and leaks it. From this perspective, it is preferable that the toner base particles do not substantially contain carbon black. "Substantially not containing" means that the carbon black content is less than 1% by mass with respect to the total mass of the toner base particles and external additives combined.

[0067] [1.2 Binder resin] The toner according to the present invention preferably contains a binder resin in the toner base particles.

[0068] The term "binding resin (also called "binder resin")" refers to a resin that is used as a medium or matrix (parent body) for dispersing internal additives (wax, charge control agent, pigment, etc.) and external additives (silica, titanium oxide, etc.) contained in toner particles, and has the function of adhering to a recording medium (e.g. paper) during the fixing process of a toner image.

[0069] From the viewpoint of fixing (fixing) the toner to an image support (recording medium) such as paper by heat, the binder resin is preferably a thermoplastic resin. The thermoplastic resin is not particularly limited as long as it has the above-mentioned functions, and examples thereof include styrene resin, vinyl resin (acrylic resin, styrene-acrylic resin, etc.), polyester resin, silicone resin, olefin resin, polyamide resin, and epoxy resin, etc. These may be used alone or in combination of two or more.

[0070] The binder resin may be a crystalline resin or an amorphous resin.

[0071] [1.2.1 Crystalline resin] In the present invention, the term "crystalline resin" refers to a resin that has a clear endothermic peak, not a stepwise endothermic change, in a differential calorimeter (DSC) measured differential scanning calorimeter (DSC). Specifically, a clear endothermic peak means a peak whose half-width is within 15°C when measured at a heating rate of 10°C / min in DSC measurement. The DSC measurement uses a differential scanning calorimeter (PerkinElmer: Diamond DSC), and the melting points of indium and zinc are used to correct the temperature of the detector of this device, and the heat of fusion of indium is used to correct the heat quantity.

[0072] Such crystalline resins have high viscosity just before the melting point due to their high crystallinity, and the viscosity drops sharply around the melting point (sharp melting property). Therefore, by including a crystalline resin in the binder resin, a toner having high storage stability in a high temperature environment (heat-resistant storage stability) and high fixability can be obtained.

[0073] The melting point (Tm) of the crystalline resin is preferably within a range of 55 to 90°C, and more preferably within a range of 70 to 85°C, from the viewpoints of low-temperature fixability and hot offset resistance. The melting point of the crystalline resin can be controlled by the resin composition.

[0074] The melting point (Tm) is the temperature at the top of the endothermic peak, and can be measured by DSC. Specifically, the sample is sealed in an aluminum pan KINTO.B0143013 and set in the sample holder of a thermal analysis device Diamond DSC (PerkinElmer), and the temperature is changed in the order of heating, cooling, and heating. In the first heating, the temperature is raised from room temperature (25°C), and in the second heating, the temperature is raised from 0°C at a heating rate of 10°C / min to 150°C and held at 150°C for 5 minutes, and in the cooling, the temperature is lowered from 150°C to 0°C at a heating rate of 10°C / min and held at 0°C for 5 minutes. The temperature at the top of the endothermic peak in the endothermic curve obtained in the second heating is measured as the melting point.

[0075] From the viewpoint of low-temperature fixing property and heat-resistant storage property, the content of the crystalline resin in the toner base particles is preferably within a range of 1 to 40% by mass, and more preferably within a range of 5 to 30% by mass, based on the total mass of the toner base particles. If the content of the crystalline resin is 1% by mass or more, sufficient low-temperature fixing property is obtained, and if it is 40% by mass or less, sufficient thermal stability, stability against physical stress, and heat-resistant storage property as a toner are obtained.

[0076] From the viewpoint of low temperature fixability and heat resistance, the content of the crystalline resin is preferably within a range of 2 to 20% by mass, more preferably within a range of 5 to 20% by mass, and even more preferably within a range of 7 to 15% by mass, based on the total mass of the binder resin. If the content of the crystalline resin is 2% by mass or more, a sufficient plasticizing effect is obtained and low temperature fixability is more remarkable, and if it is 20% by mass or less, heat resistance is improved and sufficient thermal stability as a toner, stability against physical stress, and heat-resistant storage stability are obtained.

[0077] From the viewpoint of low-temperature fixing ability and gloss stability, the number average molecular weight (Mn) of the crystalline resin is preferably within the range of 3000 to 12500, and more preferably within the range of 4000 to 11000. Moreover, the weight average molecular weight (Mw) of the crystalline resin is preferably within the range of 10000 to 100000, more preferably within the range of 15000 to 80000, and even more preferably within the range of 20000 to 50000.

[0078] When Mw and Mn are within the above ranges, sharp melting properties are easily exhibited and fixing temperature is easily controlled. In addition, sufficient strength is obtained in the fixed image. Furthermore, in the production of the toner, the crystalline resin is not pulverized during stirring of the emulsion, and the glass transition temperature Tg of the toner is kept constant, so that the thermal stability of the toner is maintained. Mw and Mn can be determined from the molecular weight distribution measured by gel permeation chromatography (GPC) as follows.

[0079] (Method of measuring molecular weight of crystalline resin) The sample is added to tetrahydrofuran (THF) so that the concentration is 0.1 mg / mL, and then heated to 40°C to completely dissolve it, and then treated with a membrane filter with a pore size of 0.2 μm to prepare a sample solution (sample). Then, the measurement was performed under the following conditions. In detail, a GPC device HLC-8220GPC (manufactured by Tosoh Corporation) and a column "TSKgel Super H3000" (manufactured by Tosoh Corporation) are used, and THF is passed as a carrier solvent (eluent) at a flow rate of 0.6 mL / min while maintaining the column temperature at 40°C. 100 μL of the prepared sample solution is injected into the GPC device together with the carrier solvent, and the sample is detected using a differential refractive index detector (RI detector). Then, the molecular weight distribution of the sample is calculated using a calibration curve measured using 10 points of monodisperse polystyrene standard particles. In addition, in the data analysis, if a peak caused by the filter is confirmed, a baseline is set up to the peak, and the analyzed data is taken as the molecular weight of the sample.

[0080] Measurement model: Tosoh Corporation GPC device HLC-8220GPC Column: Tosoh Corporation "TSKgelSuperH3000" Eluent:THF Temperature: Column thermostat 40.0℃ Flow rate: 0.6ml / min Concentration: 0.1mg / mL (0.1wt / vol%) Calibration curve: Standard polystyrene sample manufactured by Tosoh Corporation Injection volume: 100μL Solubility: Completely dissolved (heated at 40℃) Pretreatment: Filtration through a 0.2μm filter Detector: Differential refractometer (RI)

[0081] The crystalline resin may be used alone or in combination of two or more. The type of crystalline resin is not particularly limited, and examples thereof include crystalline polyolefin resin, crystalline polydiene resin, crystalline polyester resin, crystalline polyamide resin, crystalline polyurethane resin, crystalline polyacetal resin, crystalline polyethylene terephthalate resin, crystalline polybutylene terephthalate resin, crystalline polyphenylene sulfide resin, crystalline polyether ether ketone resin, and crystalline polytetrafluoroethylene resin. Among these, crystalline polyester resin is preferred from the viewpoint of low-temperature fixability and gloss stability. The crystalline polyester resin melts during heat fixation and acts as a plasticizer for the amorphous resin, so that it can improve low-temperature fixability.

[0082] From the viewpoint of low-temperature fixability and heat-resistant storage stability, it is preferable to use a combination of a crystalline polyester resin and an amorphous resin as the binder resin, and it is more preferable to use a combination of a crystalline polyester resin and a vinyl resin.

[0083] [Crystalline polyester] The term "crystalline polyester (hereinafter also referred to as "crystalline polyester resin")" refers to a resin that, among known polyester resins obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polycarboxylic acid) and a divalent or higher alcohol (polyalcohol), shows a clear endothermic peak rather than a stepwise endothermic change in the above-described differential scanning calorimetry (DSC).

[0084] In addition, the crystalline polyester resin melts during thermal fixing and acts as a plasticizer for the amorphous resin, thereby improving the low-temperature fixing property of the toner. The crystalline polyester resin may be used alone or in combination of two or more kinds.

[0085] The crystalline polyester resin is not particularly limited as long as it is as defined above. For example, a resin having a structure in which other components are copolymerized in the main chain of a crystalline polyester resin is also included in the crystalline polyester resin of the present invention as long as the resin shows the above-mentioned clear endothermic peak.

[0086] From the viewpoint of low-temperature fixability and gloss stability, the number average molecular weight (Mn) of the crystalline polyester resin is preferably within the range of 3000 to 12500, more preferably within the range of 4000 to 11000. The weight average molecular weight (Mw) of the crystalline polyester resin is preferably within the range of 10000 to 100000, more preferably within the range of 12000 to 80000, and even more preferably within the range of 14000 to 50000. Within the above ranges, the melting point of the toner obtained is within a suitable range, and the toner has excellent blocking resistance and low-temperature fixability. The number average molecular weight (Mn) and weight average molecular weight (Mw) can be measured by the above-mentioned gel permeation chromatography (GPC).

[0087] The acid value (AV) of the crystalline polyester resin is preferably 5 to 70 mgKOH / g. The acid value can be measured in accordance with the method described in JIS K2501:2003.

[0088] When the crystalline resin contained in the binder resin is a crystalline polyester resin, the content of the crystalline polyester resin is preferably within a range of 2 to 20% by mass, more preferably within a range of 5 to 20% by mass, and even more preferably within a range of 7 to 15% by mass, based on the total mass of the binder resin. If the content of the crystalline polyester resin is 2% by mass or more, the toner has excellent low-temperature fixing properties, and if it is 20% by mass or less, the toner has excellent heat resistance.

[0089] The crystalline polyester resin is produced from a polybasic carboxylic acid component and a polyhydric alcohol component. The valence of each of the polybasic carboxylic acid component and the polyhydric alcohol component is preferably 2 to 3, and particularly preferably 2.

[0090] (Polycarboxylic Acid) The "polycarboxylic acid" is a compound containing two or more carboxy groups in one molecule. An example of the polycarboxylic acid is dicarboxylic acid. The dicarboxylic acid may be used alone or in combination of two or more. The dicarboxylic acid is preferably an aliphatic dicarboxylic acid, and may further contain an aromatic dicarboxylic acid. The aliphatic dicarboxylic acid is preferably a straight-chain type from the viewpoint of increasing the crystallinity of the crystalline polyester resin.

[0091] Examples of the aliphatic dicarboxylic acid include saturated aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid (hexanedioic acid), pimelic acid, suberic acid (octanedioic acid), azelaic acid, sebacic acid (decanedioic acid), n-dodecyl succinic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid (dodecanedioic acid), 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid (tetradecanedioic acid), 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid, lower alkyl esters thereof, and acid anhydrides thereof. Among these, from the viewpoint of compatibility between low-temperature fixability and transferability, aliphatic dicarboxylic acids having 6 to 16 carbon atoms are preferred, and aliphatic dicarboxylic acids having 10 to 14 carbon atoms are more preferred.

[0092] Examples of the aromatic dicarboxylic acid include phthalic acid, terephthalic acid, isophthalic acid, orthophthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid. Among them, terephthalic acid, isophthalic acid, and t-butylisophthalic acid are preferred from the viewpoints of availability and ease of emulsification.

[0093] In addition to the above, examples of the polyvalent carboxylic acid include alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid, and anhydrides or alkyl esters having 1 to 3 carbon atoms of these carboxylic acid compounds.

[0094] The polyvalent carboxylic acids may be used alone or in combination of two or more kinds.

[0095] From the viewpoint of the crystallinity of the crystalline polyester resin, the content of the constituent units derived from aliphatic dicarboxylic acids relative to the constituent units derived from dicarboxylic acids is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 100 mol%.

[0096] (Polyhydric alcohol) A "polyhydric alcohol" is a compound containing two or more hydroxyl groups in one molecule. An example of the polyhydric alcohol component is a diol. The diol may be used alone or in combination of two or more. The diol is preferably an aliphatic diol, and may further contain other diols. The aliphatic diol is preferably a straight-chain type from the viewpoint of increasing the crystallinity of the crystalline polyester resin.

[0097] Examples of the aliphatic diol include ethylene glycol, propylene glycol (1,2-propanediol), 1,3-propanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,20-eicosanediol. Among them, from the viewpoint of compatibility between low-temperature fixing property and transferability, aliphatic diols having 2 to 20 carbon atoms are preferred, and aliphatic diols having 4 to 12 carbon atoms are more preferred.

[0098] Examples of the other diols include diols having a double bond and diols having a sulfonic acid group.Specific examples of the diols having a double bond include 1,4-butenediol, 2-butene-1,4-diol, 3-butene-1,6-diol, and 4-butene-1,8-diol.

[0099] Examples of trihydric or higher polyhydric alcohols include glycerin, pentaerythritol, trimethylolpropane, and sorbitol.

[0100] The polyhydric alcohols may be used alone or in combination of two or more kinds.

[0101] From the viewpoints of low-temperature fixability and gloss stability, the content of the aliphatic diol-derived structural units relative to the diol-derived structural units is preferably 50 mol % or more, more preferably 70 mol % or more, even more preferably 80 mol % or more, and particularly preferably 100 mol %.

[0102] The ratio of diol to dicarboxylic acid in the monomers constituting the crystalline polyester resin, i.e., the equivalent ratio [-OH] / [-COOH] of the hydroxy group [-OH] of the diol to the carboxy group [-COOH] of the dicarboxylic acid, is preferably within the range of 2.0 / 1.0 to 1.0 / 2.0, more preferably within the range of 1.5 / 1.0 to 1.0 / 1.5, and even more preferably within the range of 1.3 / 1.0 to 1.0 / 1.3.

[0103] The monomer constituting the crystalline polyester resin preferably contains 50% by mass or more of a linear aliphatic monomer, more preferably 80% by mass or more. When a linear aliphatic monomer is used, the crystallinity of the crystalline polyester resin is high, and the melting point (the temperature at the top of the endothermic peak) is often high. When a branched aliphatic monomer is used, the crystallinity is low, and the melting point is often low. Therefore, it is preferable to use a linear aliphatic monomer as the monomer.

[0104] The crystalline polyester resin can be synthesized by polycondensing (esterifying) the above-mentioned polyvalent carboxylic acid and polyhydric alcohol using a known esterification catalyst.

[0105] The esterification catalyst may be used alone or in combination of two or more. Examples of the esterification catalyst include alkali metal compounds such as sodium and lithium, compounds containing Group 2 elements such as magnesium and calcium, metal compounds such as aluminum, zinc, manganese, antimony, titanium, tin, zirconium, and germanium, phosphorous compounds, phosphoric acid compounds, and amine compounds.

[0106] Specifically, examples of tin compounds include dibutyltin oxide, tin octoate, tin dioctoate, and salts thereof. Examples of titanium compounds include titanium alkoxides such as tetra-normal-butyl titanate, tetraisopropyl titanate, tetramethyl titanate, and tetrastearyl titanate; titanium acylates such as polyhydroxytitanium stearate; and titanium chelates such as titanium tetraacetylacetonate, titanium lactate, and titanium triethanolamine. Examples of germanium compounds include germanium dioxide, and examples of aluminum compounds include oxides such as polyaluminum hydroxide, aluminum alkoxides, and tributylaluminate.

[0107] The polymerization temperature for the crystalline polyester resin is preferably within a range of 150 to 250° C. The polymerization time is preferably within a range of 0.5 to 10 hours. During the polymerization, the pressure in the reaction system may be reduced as necessary.

[0108] The crystallinity and heat of fusion of the crystalline polyester resin can be controlled by selecting the structure and constituent monomer of the crystalline polyester resin. From the viewpoint of adjusting the crystallinity of the crystalline polyester resin to a range preferred for fixing, the crystalline polyester resin is preferably a hybrid crystalline polyester resin described below. The hybrid crystalline polyester resin may be used alone or in combination of two or more kinds. The hybrid crystalline polyester resin may replace the entire amount of the crystalline polyester resin or may replace a part of the crystalline polyester resin.

[0109] [Hybrid crystalline polyester resin] The crystalline resin according to the present invention is preferably a crystalline polyester resin, and from the viewpoint of low-temperature fixability, the crystalline polyester resin is preferably a hybrid crystalline polyester resin containing a crystalline polyester resin structure and an amorphous resin structure. Since the hybrid crystalline polyester resin contains an amorphous resin structure, it has high compatibility with the amorphous resin and can maintain a more finely dispersed state in the binder resin, and since it contains a crystalline polyester resin structure, the sharp melting property of the crystalline resin is more exhibited during fixing, improving low-temperature fixability. In addition, when the toner base particles have a core-shell structure, it is preferable to include a hybrid crystalline polyester resin in the core portion from the viewpoint of making it difficult for the crystalline polyester resin to be exposed on the surface of the toner base particles.

[0110] The hybrid crystalline polyester resin is a resin having a structure in which a crystalline polyester polymerized segment and an amorphous polymerized segment are chemically bonded. The crystalline polyester polymerized segment means a portion derived from a crystalline polyester resin. That is, it means a molecular chain having the same chemical structure as the molecular chain constituting the crystalline polyester resin described above. The amorphous polymerized segment means a portion derived from an amorphous resin. That is, it means a molecular chain having the same chemical structure as the molecular chain constituting the amorphous resin described below.

[0111] The weight average molecular weight (Mw) of the hybrid crystalline polyester resin is preferably within the range of 20,000 to 50,000. By setting Mw to 50,000 or less, sufficient low-temperature fixing property can be obtained. On the other hand, by setting Mw to 20,000 or more, excessive progress of compatibility between the hybrid resin and the amorphous resin during toner storage can be suppressed, and image defects due to fusion between toner particles can be suppressed. The weight average molecular weight can be measured by the above-mentioned method for measuring the molecular weight of the crystalline resin.

[0112] For the same reason, the number average molecular weight (Mn) of the hybrid crystalline polyester resin is preferably within the range of 3,000 to 12,500, and more preferably within the range of 4,000 to 11,000.

[0113] When the crystalline resin contains a hybrid crystalline polyester resin, the content of the hybrid crystalline polyester resin is preferably within a range of 2 to 20% by mass, more preferably within a range of 5 to 20% by mass, and even more preferably within a range of 7 to 15% by mass, based on the total mass of the binder resin. When the content of the hybrid crystalline polyester resin is 2% by mass or more, the low-temperature fixing property is excellent, and when it is 20% by mass or less, the heat resistance is excellent.

[0114] The structure of the chemical bond is not particularly limited and may be a block copolymer or a graft copolymer, but is preferably a structure in which the crystalline polyester polymerized segment is grafted to the amorphous polymerized segment as the main chain. That is, the hybrid crystalline polyester resin is preferably a graft copolymer having an amorphous polymerized segment as the main chain and a crystalline polyester polymerized segment as a side chain.

[0115] The hybrid crystalline polyester resin having such a structure will be described below.

[0116] (Crystalline polyester polymerized segment) The term "crystalline polyester polymer segment" refers to a portion derived from a crystalline polyester resin, that is, a molecular chain having the same chemical structure as that constituting the crystalline polyester resin.

[0117] The crystalline polyester polymerized segment is synonymous with the crystalline polyester resin described above, and is a portion derived from a known polyester resin obtained by polycondensation reaction of a polycarboxylic acid and a polyhydric alcohol. The crystalline polyester polymerized segment can be synthesized from a polycarboxylic acid and a polyhydric alcohol in the same manner as the crystalline polyester resin described above. Note that the polycarboxylic acid component and the polyhydric alcohol component constituting the crystalline polyester polymerized segment are the same as those described in the "polycarboxylic acid" and "polyhydric alcohol" items in the crystalline polyester resin described above, and therefore will not be described here.

[0118] The content of the crystalline polyester polymer segment is preferably within a range of 80 to 98% by mass, more preferably within a range of 90 to 95% by mass, based on the total mass of the hybrid crystalline polyester resin. By being within the above range, sufficient crystallinity can be imparted to the hybrid crystalline polyester resin. The components and contents of each segment in the hybrid crystalline polyester resin (or toner particles) can be identified by utilizing known analytical methods such as nuclear magnetic resonance (NMR) measurement and methylation reaction pyrolysis gas chromatography / mass spectrometry (Py-GC / MS).

[0119] The crystalline polyester polymerized segment preferably contains a monomer having an unsaturated bond from the viewpoint of introducing a chemical bonding site with the amorphous polymerized segment into the segment. The monomer having an unsaturated bond is, for example, a polyvalent carboxylic acid and a polyhydric alcohol having a double bond, and examples thereof include polyvalent carboxylic acids such as methylene succinic acid, fumaric acid, maleic acid, 3-hexenedioic acid, and 3-octenedioic acid; and polyhydric alcohols such as 2-butene-1,4-diol, 3-butene-1,6-diol, and 4-butene-1,8-diol. The content of the constituent unit derived from the monomer having an unsaturated bond in the crystalline polyester polymerized segment is preferably within a range of 0.5 to 20% by mass with respect to the total mass of the crystalline polyester polymerized segment.

[0120] The hybrid crystalline polyester resin may further include a functional group such as a sulfonic acid group, a carboxy group, or a urethane group. The functional group may be introduced into the crystalline polyester polymer segment or into the amorphous polymer segment.

[0121] (Amorphous polymerized segment) The term "amorphous polymerized segment" refers to a portion derived from an amorphous resin. In other words, it refers to a molecular chain having the same chemical structure as that constituting the amorphous resin. When the binder resin according to the present invention contains an amorphous resin, the amorphous polymerized segment enhances the compatibility between the hybrid crystalline polyester resin and the amorphous resin. As a result, the hybrid crystalline resin is easily incorporated into the amorphous resin, and the charging uniformity of the toner is further improved. The components and the content of the amorphous polymerized segment in the hybrid crystalline polyester resin (or toner particles) can be identified by utilizing known analytical methods such as nuclear magnetic resonance (NMR) measurement and methylation reaction pyrolysis gas chromatography / mass spectrometry (Py-GC / MS).

[0122] The amorphous polymer segment is a polymer segment that has no melting point and a relatively high glass transition temperature (Tg) when a differential scanning calorimetry (DSC) is performed on a resin having the same chemical structure and molecular weight. The amorphous polymer segment preferably has a glass transition temperature (Tg) in the first heating process of DSC in the same range as the amorphous resin, and more preferably has a glass transition temperature (Tg) in the range of 30 to 80°C, and more preferably in the range of 40 to 65°C. The glass transition temperature (Tg) can be measured in the same manner as the Tg of the amorphous resin.

[0123] The amorphous polymer segment is preferably composed of the same type of resin as the amorphous resin (e.g., vinyl resin) contained in the binder resin, from the viewpoint of increasing compatibility with the binder resin and increasing the charging uniformity of the toner. By adopting such a form, the compatibility between the hybrid crystalline polyester resin and the amorphous resin is further improved. The "same type of resin" means resins having characteristic chemical bonds in the repeating units.

[0124] The "characteristic chemical bonds" are based on the "polymer classification" described in the National Institute for Materials Science (NIMS) Materials Database (http: / / polymer.nims.go.jp / PoLyInfo / guide / jp / term_polymer.html). In other words, the chemical bonds that make up polymers classified into a total of 22 types, including polyacrylic, polyamide, polyanhydride, polycarbonate, polydienes, polyesters, polyhaloolefins, polyimides, polyimines, polyketones, polyolefins, polyethers, polyphenylenes, polyphosphazenes, polysiloxanes, polystyrenes, polysulfides, polysulfones, polyurethanes, polyureas, polyvinyls, and other polymers, are called "characteristic chemical bonds."

[0125] In addition, when the resin is a copolymer, "same type of resin" means resins that have a common characteristic chemical bond when the monomer species having the above-mentioned chemical bond is used as a constituent unit in the chemical structure of a plurality of monomer species that constitute the copolymer. Therefore, even if the properties exhibited by the resins themselves are different from each other or the molar component ratios of the monomer species that constitute the copolymer are different from each other, they are considered to be the same type of resins as long as they have a common characteristic chemical bond.

[0126] For example, a resin (or a polymerized segment) formed by styrene, butyl acrylate, and acrylic acid and a resin (or a polymerized segment) formed by styrene, butyl acrylate, and methacrylic acid have at least a chemical bond constituting polyacrylic, and therefore, they are the same type of resin. For further example, a resin (or a polymerized segment) formed by styrene, butyl acrylate, and acrylic acid and a resin (or a polymerized segment) formed by styrene, butyl acrylate, acrylic acid, terephthalic acid, and fumaric acid have at least a chemical bond constituting polyacrylic as a common chemical bond. Therefore, they are the same type of resin.

[0127] From the viewpoint of introducing a chemical bonding site with the crystalline polyester polymer segment into the amorphous polymer segment, the amorphous polymer segment preferably contains an amphoteric compound, which will be described later, in the monomer. The content of the constitutional unit derived from the amphoteric compound is preferably within a range of 0.5 to 20% by mass with respect to the total mass of the amorphous polymer segment.

[0128] From the viewpoint of imparting sufficient crystallinity to the hybrid crystalline polyester resin, the content of the amorphous polymer segment is preferably within the range of 2 to 20 mass%, more preferably within the range of 3 to 15 mass%, even more preferably within the range of 5 to 10 mass%, and particularly preferably within the range of 7 to 9 mass%, relative to the total mass of the hybrid crystalline polyester resin.

[0129] The resin component constituting the amorphous polymerized segment is not particularly limited, and examples thereof include a vinyl polymerized segment, a urethane polymerized segment, a urea polymerized segment, etc. Among these, from the viewpoint of thermoplasticity, a vinyl polymerized segment is preferred.

[0130] In addition, when the vinyl polymerization segment is used, it is preferable to use a vinyl resin as the amorphous resin in the binder resin, and moreover, it is preferable that the vinyl resin is contained in the binder resin in the largest proportion. This increases the compatibility between the vinyl polymerization segment and the vinyl resin, and the hybrid crystalline polyester resin can be kept in a more finely dispersed state in the binder resin, and the sharp melting property of the crystalline resin is more likely to be exhibited during fixing. The vinyl polymerization segment can be synthesized in the same manner as the vinyl resin.

[0131] The vinyl polymerized segment is not particularly limited as long as it is a polymerized vinyl compound, and examples thereof include an acrylic acid ester polymerized segment, a styrene-acrylic acid ester polymerized segment, an ethylene-vinyl acetate polymerized segment, etc. These may be used alone or in combination of two or more.

[0132] Among the above vinyl polymerized segments, in consideration of the plasticity during thermal fixing, the styrene-acrylic ester polymerized segment (also simply referred to as "styrene-acrylic polymerized segment") is preferred. Therefore, the styrene-acrylic polymerized segment as an amorphous polymerized segment will be described below.

[0133] (styrene-acrylic polymerized segment) The styrene-acrylic polymer segment is formed by addition polymerization of at least a styrene monomer and a (meth)acrylic acid ester monomer. The styrene monomer referred to here is CH 2 =CH-C 6 H 5 In addition to styrene represented by the structural formula, it includes structures having known side chains or functional groups in the styrene structure. In addition, the (meth)acrylic acid ester monomer referred to here is CH 2 In addition to acrylic acid ester compounds represented by =CHCOOR (R is an alkyl group) and methacrylic acid ester compounds, the compounds include ester compounds having known side chains or functional groups in the structure of acrylic acid ester derivatives and methacrylic acid ester derivatives.

[0134] Specific examples of styrene monomers and (meth)acrylic acid ester monomers capable of forming the styrene-acrylic polymerization segment are shown below, but those usable for forming the styrene-acrylic polymerization segment used in the present invention are not limited to the following.

[0135] (styrene monomer) Specific examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, etc. These styrene monomers may be used alone or in combination of two or more.

[0136] ((Meth)acrylic acid ester monomer) Specific examples of (meth)acrylic acid ester monomers include acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, and phenyl acrylate; and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, and dimethylaminoethyl methacrylate. Among these, it is preferable to use a long-chain acrylic acid ester monomer. Specifically, methyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate are preferred.

[0137] In this specification, the term "(meth)acrylic acid ester monomer" collectively refers to "acrylic acid ester monomer" and "methacrylic acid ester monomer", for example, "methyl (meth)acrylate" collectively refers to "methyl acrylate" and "methyl methacrylate".

[0138] These acrylic acid ester monomers or methacrylic acid ester monomers may be used alone or in combination of two or more. That is, it is possible to form a copolymer using a styrene monomer and two or more acrylic acid ester monomers, to form a copolymer using a styrene monomer and two or more methacrylic acid ester monomers, or to form a copolymer using a styrene monomer in combination with an acrylic acid ester monomer and a methacrylic acid ester monomer.

[0139] From the viewpoint of plasticity, the content of the structural units derived from the styrene monomer in the styrene-acrylic polymerization segment is preferably within a range of 40 to 90% by mass relative to the total mass of the styrene-acrylic polymerization segment. From the same viewpoint, the content of the structural units derived from the (meth)acrylic acid ester monomer in the styrene-acrylic polymerization segment is preferably within a range of 10 to 60% by mass relative to the total mass of the styrene-acrylic polymerization segment.

[0140] Furthermore, the styrene-acrylic polymerization segment is preferably formed by addition polymerization of a compound for chemically bonding to the crystalline polyester polymerization segment in addition to the styrene monomer and (meth)acrylic acid ester monomer. Specifically, it is preferable to use a compound that forms an ester bond with the hydroxy group [-OH] derived from the polyhydric alcohol component or the carboxy group [-COOH] derived from the polycarboxylic acid component contained in the crystalline polyester polymerization segment. Therefore, the styrene-acrylic polymerization segment is preferably formed by further polymerizing a compound that can be addition polymerized with the styrene monomer and (meth)acrylic acid ester monomer and has a carboxy group [-COOH] or a hydroxy group [-OH].

[0141] Examples of such compounds include compounds having a carboxy group, such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl esters, and itaconic acid monoalkyl esters; and compounds having a hydroxy group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and polyethylene glycol mono(meth)acrylate.

[0142] The content of the constituent units derived from the above compounds in the styrene-acrylic polymerization segment is preferably within a range of 0.5 to 20 mass % relative to the total mass of the styrene-acrylic polymerization segment, from the viewpoint of introducing chemical bonding sites with the above crystalline polyester polymerization segment into the styrene-acrylic polymerization segment.

[0143] The method for forming the styrene-acrylic polymerized segment is not particularly limited, and examples thereof include a method of polymerizing monomers using a known oil-soluble or water-soluble polymerization initiator. Specific examples of the oil-soluble polymerization initiator include the following azo or diazo polymerization initiators and peroxide polymerization initiators.

[0144] (Azo or diazo polymerization initiator) Examples of the azo or diazo polymerization initiator include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and azobisisobutyronitrile.

[0145] (Peroxide-based polymerization initiator) Examples of the peroxide polymerization initiator include benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxypivalate, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-(4,4-t-butylperoxycyclohexyl)propane, and tris-(t-butylperoxy)triazine.

[0146] When resin particles are formed by emulsion polymerization, a water-soluble radical polymerization initiator can be used, such as persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

[0147] (Method for producing hybrid crystalline polyester resin) The method for producing the hybrid crystalline polyester resin is not particularly limited as long as it is a method capable of forming a polymer having a structure in which the above-mentioned crystalline polyester polymerized segment and the amorphous polymerized segment are chemically bonded. As a specific method for producing the hybrid crystalline polyester resin, for example, it can be produced by the following first to third production methods.

[0148] (First manufacturing method) The first production method is a method for producing a hybrid crystalline polyester resin by carrying out a polymerization reaction for synthesizing a crystalline polyester polymer segment in the presence of a pre-synthesized amorphous polymer segment.

[0149] (Second manufacturing method) The second production method is a method in which a crystalline polyester polymer segment and an amorphous polymer segment are formed in advance, and then these are bonded to produce a hybrid crystalline polyester resin.

[0150] (Third manufacturing method) The third production method is a method of producing a hybrid crystalline polyester resin by carrying out a polymerization reaction to synthesize an amorphous polymer segment in the presence of a crystalline polyester polymer segment.

[0151] Among the above first to third manufacturing methods, the first manufacturing method is preferred because it is easy to synthesize a hybrid crystalline polyester resin having a structure in which a crystalline polyester polymer chain (crystalline polyester resin chain) is grafted to an amorphous polymer chain (amorphous resin chain) and because it can simplify the production process. The first manufacturing method is preferred because the orientation of the crystalline polyester polymer segment is easily uniform because the amorphous polymer segment is formed in advance and then the crystalline polyester polymer segment is bonded to the amorphous polymer segment. Therefore, it is preferred from the viewpoint of easy synthesis of a hybrid crystalline polyester resin suitable for the toner of the present invention.

[0152] [1.2.2 Amorphous resin] The toner base particles according to the present invention preferably contain, as a binder resin, an amorphous resin in addition to a crystalline resin. The amorphous resin is a resin that does not have the above-mentioned "crystallinity". By including the amorphous resin in the toner base particles, the crystalline resin and the amorphous resin become compatible with each other during heat fixing, thereby improving the low-temperature fixing property of the toner.

[0153] In other words, an "amorphous resin" is a resin that does not have a melting point (i.e., does not have the aforementioned clear endothermic peak upon heating) and has a relatively high glass transition temperature (Tg) in the endothermic curve obtained when differential scanning calorimetry (DSC) is performed.

[0154] In the present invention, the Tg of the amorphous resin is preferably within the range of 35 to 80°C, and more preferably within the range of 45 to 65°C.

[0155] From the viewpoint of achieving both low-temperature fixing property, hot offset resistance and heat resistance, it is preferable that the toner base particles have a core-shell structure. When the core portion of the core-shell structure contains a particle of a three-layer structure of a release agent (wax)-containing amorphous resin (for example, a release agent-containing amorphous vinyl resin), the Tg of the amorphous resin constituting the outermost layer of the particle is preferably within the range of 55 to 65°C.

[0156] The glass transition temperature can be measured according to the method (DSC method) specified in ASTM D3418-82. For the measurement, a DSC-7 differential scanning calorimeter (manufactured by PerkinElmer), a TAC7 / DX thermal analyzer controller (manufactured by PerkinElmer), or the like can be used.

[0157] From the viewpoint of plasticity, the weight average molecular weight (Mw) of the amorphous resin is preferably within a range of 20,000 to 150,000, and more preferably within a range of 25,000 to 130,000. From the viewpoint of plasticity, the number average molecular weight (Mn) of the amorphous resin is preferably within a range of 5,000 to 150,000, and more preferably within a range of 8,000 to 70,000. The molecular weight of the amorphous resin can be measured in the same manner as the method for measuring the molecular weight of the crystalline resin described above.

[0158] The mass ratio of the amorphous resin to the crystalline resin (amorphous resin / crystalline resin) is preferably within a range of 98 / 2 to 80 / 20, more preferably within a range of 95 / 5 to 80 / 20. By having the mass ratio within the above range, the crystalline resin is not exposed on the surface of the toner base particles, or even if it is exposed, the amount of the crystalline resin is extremely small, and an amount of the crystalline resin sufficient to achieve low-temperature fixability can be introduced into the toner particles.

[0159] The amorphous resin is preferably used as a binder resin together with the crystalline resin to constitute the toner base particles. By including the amorphous resin, appropriate fixed image strength and image gloss can be obtained, and good charging characteristics can be imparted even in an environment of varying temperature and humidity.

[0160] Furthermore, when the toner base particles according to the present invention have a core-shell structure, from the viewpoints of controllability of the dispersion state in the toner base particles and charging characteristics, it is preferable that an amorphous vinyl resin and a crystalline polyester resin form the core portion, and a hybrid amorphous polyester resin form the shell layer.

[0161] The amorphous resin may be used alone or in combination of two or more. Examples of the amorphous resin include vinyl resin, urethane resin, urea resin, and amorphous polyester resin such as styrene-acrylic modified polyester resin. From the viewpoint of thermoplasticity, the amorphous resin preferably contains an amorphous vinyl resin (also simply referred to as vinyl resin). These amorphous resins can be obtained by known synthesis methods or as commercially available products.

[0162] The vinyl resin will be described below.

[0163] (Vinyl resin) The binder resin according to the present invention is preferably mainly composed of a vinyl resin. By using a vinyl resin as the main component, it is easy to adjust the compatibility / immiscibility between the crystalline resin and the amorphous resin, and the crystalline polyester resin can be kept in a finely dispersed state in the binder resin, particularly in the vinyl resin as the main component, so that the sharp melting property of the crystalline polyester resin is more effectively exhibited during fixing.

[0164] The content of the vinyl resin is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 85% by mass or more, based on the total mass of the binder resin. By using the vinyl resin as the main component (50% by mass or more based on the total mass of the binder resin), it is easy to adjust the compatibility with the crystalline resin, and low-temperature fixability and heat resistance can be both achieved. The upper limit of the content of the vinyl resin is not particularly limited, but is preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 93% by mass or less, based on the total mass of the binder resin.

[0165] The binder resin according to the present invention preferably contains a vinyl resin as a main component and further contains an amorphous polyester resin, because the inclusion of the amorphous polyester resin makes it easier to adjust the compatibility with the crystalline resin.

[0166] In addition, when the toner base particles have a core-shell structure, since the amorphous polyester resin has better heat resistance than the vinyl resin, the toner can have both high heat resistance and low-temperature fixability by providing a shell layer using the amorphous polyester resin. From this viewpoint, the content of the amorphous polyester resin is preferably within a range of 2 to 20% by mass, more preferably within a range of 3 to 18% by mass, and even more preferably within a range of 4 to 15% by mass, based on the total mass of the binder resin.

[0167] In the present invention, the vinyl resin is, for example, a polymer of a vinyl compound, and examples thereof include acrylic acid ester resin, styrene-acrylic acid ester resin, ethylene-vinyl acetate resin, etc. These may be used alone or in combination of two or more. Among them, styrene-acrylic acid ester resin (styrene-acrylic resin) is preferable from the viewpoint of plasticity during thermal fixing. The styrene monomer and (meth)acrylic acid ester monomer used in the styrene-acrylic resin may be the same as those described in the above-mentioned items "styrene monomer" and "(meth)acrylic acid ester monomer".

[0168] Styrene-acrylic resins are formed by addition polymerization of at least a styrene monomer and a (meth)acrylic acid ester monomer. The styrene monomer is CH 2 =CH-C 6 H 5 In addition to styrene represented by the structural formula above, styrene derivatives having known side chains or functional groups in the styrene structure are also included.

[0169] In addition, the (meth)acrylic acid ester monomer is CH(R 1 )=CHCOOR 2 (R 1represents a hydrogen atom or a methyl group, R 2 In addition to the acrylic acid esters and methacrylic acid esters represented by the formula (I) (representing an alkyl group having 1 to 24 carbon atoms), the above-mentioned acrylic acid ester derivatives and methacrylic acid ester derivatives having known side chains or functional groups in the structure of these esters are also included.

[0170] Examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, and pn-dodecylstyrene.

[0171] Examples of the (meth)acrylic acid ester monomer include acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, and phenyl acrylate; and methacrylic acid ester monomers such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, and dimethylaminoethyl methacrylate.

[0172] In this specification, the term "(meth)acrylic acid ester monomer" is a general term for "acrylic acid ester monomer" and "methacrylic acid ester monomer" and means one or both of them. For example, "methyl (meth)acrylate" means one or both of "methyl acrylate" and "methyl methacrylate".

[0173] The (meth)acrylic acid ester monomer may be used alone or in combination of two or more. For example, it is possible to form a copolymer using a styrene monomer and two or more acrylic acid ester monomers, to form a copolymer using a styrene monomer and two or more methacrylic acid ester monomers, or to form a copolymer using a styrene monomer, an acrylic acid ester monomer, and a methacrylic acid ester monomer in combination.

[0174] From the viewpoint of plasticity, the content of the structural units derived from the styrene monomer is preferably within a range of 40 to 90% by mass relative to the total mass of the amorphous resin, and the content of the structural units derived from the (meth)acrylic acid ester monomer is preferably within a range of 10 to 60% by mass relative to the total mass of the amorphous resin.

[0175] The amorphous resin may further contain a constituent unit derived from a monomer other than the above-mentioned styrene monomer and (meth)acrylic acid ester monomer. The other monomer is preferably a compound that forms an ester bond with a hydroxy group [-OH] derived from a polyhydric alcohol or a carboxy group [-COOH] derived from a polycarboxylic acid. In other words, the amorphous resin is preferably a polymer that can be addition polymerized with the above-mentioned styrene monomer and (meth)acrylic acid ester monomer, and is further polymerized with an amphoteric compound (a compound having a carboxy group or a hydroxy group).

[0176] The "amphoteric compound" in the present invention is a monomer that bonds a crystalline polyester polymerized segment and an amorphous polymerized segment, and has in its molecule a substituent such as a hydroxy group, a carboxy group, an epoxy group, a primary amino group, a secondary amino group, etc., that can react with the crystalline polyester polymerized segment, and an ethylenically unsaturated group that can react with the amorphous polymerized segment. Among these, vinyl carboxylic acid having a hydroxy group or a carboxy group and an ethylenically unsaturated group is preferred.

[0177] Examples of the amphoteric compound include compounds having a carboxy group, such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, and itaconic acid monoalkyl ester; and compounds having a hydroxy group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and polyethylene glycol mono(meth)acrylate.

[0178] The content of the constitutional units derived from the amphoteric compound is preferably within a range of 0.5 to 20% by mass relative to the total mass of the amorphous resin.

[0179] The styrene-acrylic resin can be synthesized by a method of polymerizing monomers using a known oil-soluble or water-soluble polymerization initiator. Examples of oil-soluble polymerization initiators include azo- or diazo-based polymerization initiators and peroxide-based polymerization initiators. Specifically, the method is the same as the method for forming the styrene-acrylic polymerization segment described above, so a description thereof will be omitted here.

[0180] From the viewpoint of achieving both low temperature fixability and hot offset resistance, the weight average molecular weight (Mw) of the amorphous vinyl resin is preferably within a range of 20000 to 150000, and the number average molecular weight (Mn) is preferably within a range of 5000 to 150000. The weight average molecular weight (Mw) and the number average molecular weight (Mn) can be measured in the same manner as in the case of the crystalline resin described above.

[0181] From the viewpoint of achieving both fixability and hot offset resistance, the glass transition temperature (Tg) of the amorphous vinyl resin is preferably within a range of 35 to 80° C. The glass transition temperature can be measured in the same manner as in the case of the amorphous resin described above.

[0182] (Hybrid amorphous polyester resin) The binder resin according to the present invention preferably contains a hybrid amorphous polyester resin, which has a suitable compatibility when used in combination with an amorphous vinyl resin, and which is advantageous in terms of shape controllability of the toner base particles and fixed image strength. By containing the hybrid amorphous polyester resin, it becomes easier to adjust compatibility / immiscibility and crystallization. The hybrid amorphous polyester resin can also be said to be a partially modified amorphous polyester resin.

[0183] The hybrid amorphous polyester resin preferably has a weight average molecular weight (Mw) in the range of 20,000 to 50,000. By being within the above range, it is easier to adjust the compatibility / imcompatibility and crystallization. The hybrid amorphous polyester resin preferably has a number average molecular weight (Mn) in the range of 3,000 to 12,500. The molecular weight can be measured in the same manner as in the case of the above-mentioned crystalline resin.

[0184] The hybrid amorphous polyester resin is a resin in which an amorphous polyester polymer segment and an amorphous polymer segment other than the amorphous polyester, preferably an amorphous vinyl polymer segment, are chemically bonded to each other.

[0185] The term "amorphous polyester polymerized segment" refers to a portion derived from an amorphous polyester resin. That is, it refers to a molecular chain having the same chemical structure as that constituting the amorphous polyester resin. The term "amorphous polymerized segment other than amorphous polyester" refers to a portion derived from an amorphous resin other than the amorphous polyester resin. Examples of the amorphous resin other than the amorphous polyester resin include vinyl resins such as styrene-acrylic resins, urethane resins, and urea resins. The amorphous polymerized segment other than the amorphous polyester may be used alone or in combination of two or more.

[0186] Therefore, a suitable amorphous vinyl polymer segment refers to a portion derived from an amorphous vinyl resin, that is, a molecular chain having the same chemical structure as that constituting an amorphous vinyl resin.

[0187] The hybrid amorphous polyester resin may be in any form, such as a block copolymer or a graft copolymer, so long as it contains an amorphous polyester polymer segment and an amorphous polymer segment other than the amorphous polyester, particularly an amorphous vinyl polymer segment, but is preferably a graft copolymer. By using the graft copolymer, low-temperature fixability, hot offset resistance, and mold release separability can be achieved at the same time.

[0188] From the above viewpoint, the amorphous polyester polymerized segment is preferably grafted to a main chain of an amorphous polymerized segment other than the amorphous polyester, particularly an amorphous vinyl polymerized segment. That is, the hybrid amorphous polyester resin is preferably a graft copolymer having a main chain of an amorphous polymerized segment other than the amorphous polyester, particularly an amorphous vinyl polymerized segment, and a side chain of an amorphous polyester polymerized segment.

[0189] The content of the hybrid amorphous polyester resin is preferably within a range of 3 to 20% by mass, and more preferably within a range of 5 to 15% by mass, based on the total mass of the binder resin.

[0190] (Amorphous polyester polymer segment) The amorphous polyester polymer segment is a portion derived from a known polyester resin obtained by a polycondensation reaction between a divalent or higher carboxylic acid (a polyvalent carboxylic acid component) and a divalent or higher alcohol (a polyhydric alcohol component), and refers to a polymer segment in which no clear endothermic peak is observed in DSC.

[0191] The amorphous polyester polymerized segment is not particularly limited as long as it is as defined above. For example, a resin having a structure in which other components are copolymerized in a main chain of an amorphous polyester polymerized segment, or a resin having a structure in which an amorphous polyester polymerized segment is copolymerized in a main chain of other components, corresponds to a hybrid amorphous polyester resin having an amorphous polyester polymerized segment in the present invention, so long as no clear endothermic peak is observed as described above.

[0192] (Polycarboxylic acid component) Examples of polyvalent carboxylic acid components include oxalic acid, succinic acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydroterephthalic acid, malonic acid, pimelic acid, tartaric acid, mucic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carbophthalic acid, and the like. Examples of the polycarboxylic acids include dicarboxylic acids such as xyphenylacetic acid, p-phenylene diacetic acid, m-phenylenediglycolic acid, p-phenylenediglycolic acid, o-phenylenediglycolic acid, diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracene dicarboxylic acid, and dodecenyl succinic acid; trimellitic acid, pyromellitic acid, naphthalene tricarboxylic acid, naphthalene tetracarboxylic acid, pyrene tricarboxylic acid, and pyrene tetracarboxylic acid. These polycarboxylic acids may be used alone or in combination of two or more.

[0193] Among these, from the viewpoint of easily obtaining the effects of the present invention, it is preferable to use aliphatic unsaturated dicarboxylic acids such as fumaric acid, maleic acid, and mesaconic acid, aromatic dicarboxylic acids such as isophthalic acid and terephthalic acid, succinic acid, and trimellitic acid.

[0194] (Polyhydric alcohol component) Examples of the polyhydric alcohol component include dihydric alcohols such as ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, octanediol, decanediol, dodecanediol, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A; and trihydric or higher polyols such as glycerin, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, and tetraethylolbenzoguanamine. These polyhydric alcohol components may be used alone or in combination of two or more.

[0195] Among these, dihydric alcohols such as an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A are preferred from the viewpoint of easiness in achieving the effects of the present invention.

[0196] The use ratio of the polyvalent carboxylic acid component and the polyhydric alcohol component is preferably within the range of 1.5 / 1 to 1 / 1.5, more preferably within the range of 1.2 / 1 to 1 / 1.2, in terms of the equivalent ratio [-OH] / [-COOH] of the hydroxyl group [-OH] of the polyhydric alcohol component and the carboxyl group [-COOH] of the polyvalent carboxylic acid component. By using the polyvalent alcohol component and the polyvalent carboxylic acid component within the above range, it is easier to control the acid value and molecular weight of the amorphous polyester resin.

[0197] The method for forming the amorphous polyester polymer segment is not particularly limited, and the polymer segment can be formed by polycondensing (esterifying) the polyvalent carboxylic acid component and the polyhydric alcohol component using a known esterification catalyst.

[0198] The catalyst that can be used in producing the amorphous polyester polymer segment is the same as the catalyst explained in the above section (Crystalline resin), and therefore the explanation will be omitted here.

[0199] The polymerization temperature is not particularly limited, but is preferably within the range of 150 to 250° C. The polymerization time is not particularly limited, but is preferably within the range of 0.5 to 10 hours. During the polymerization, the reaction system may be decompressed as necessary.

[0200] The content of the amorphous polyester polymerized segment in the hybrid amorphous polyester resin is preferably within the range of 50 to 99.9% by mass, more preferably within the range of 70 to 95% by mass, based on the total mass of the hybrid amorphous polyester resin. By being within the above range, both heat resistance and low-temperature fixability can be achieved. The components and contents of each polymerized segment in the hybrid amorphous polyester resin can be determined, for example, by NMR measurement or methylation reaction Py-GC / MS measurement.

[0201] The hybrid amorphous polyester resin may further include a substituent such as a sulfonic acid group, a carboxy group, or a urethane group. The introduction of the substituent may be into the amorphous polyester polymer segment or into the amorphous vinyl polymer segment described below.

[0202] (Amorphous polymerized segment) In the present invention, the amorphous polymerization segment other than the amorphous polyester polymerization segment is also simply referred to as the “amorphous polymerization segment.” When an amorphous vinyl resin is contained in the binder resin, the amorphous polymerization segment (particularly the amorphous vinyl polymerization segment) can control the compatibility between the amorphous vinyl resin and the hybrid amorphous polyester resin.

[0203] The presence of an amorphous polymer segment in the hybrid amorphous polyester resin (and further in the toner) can be confirmed by identifying the chemical structure using, for example, NMR measurement or methylation reaction Py-GC / MS measurement.

[0204] In addition, when a resin having the same chemical structure and molecular weight as the amorphous polymerized segment is subjected to differential scanning calorimetry (DSC), the amorphous polymerized segment does not have a melting point and has a relatively high glass transition temperature (Tg). The glass transition temperature (Tg) of the resin having the same chemical structure and molecular weight as the amorphous polymerized segment is preferably within the range of 35 to 80°C, and more preferably within the range of 45 to 65°C.

[0205] In the hybrid amorphous polyester resin, it is preferable to replace a part of the amorphous polyester polymerized segment with an amorphous polymerized segment, and to have a structure in which the amorphous polyester polymerized segment and the amorphous polymerized segment are bonded.For example, a resin having a structure in which a polymer in which an amorphous polyester polymerized segment and an amorphous polymerized segment are bonded is copolymerized with other components in a main chain, or a resin having a structure in which a polymer in which an amorphous polyester polymerized segment and an amorphous polymerized segment are bonded is copolymerized with a main chain made of other components corresponds to the hybrid amorphous polyester resin having an amorphous polymerized segment in the present invention.

[0206] The amorphous polymerized segment is not particularly limited, and examples thereof include polymerized vinyl compounds, polymerized polyol components and isocyanate components, polymerized urea and formaldehyde, etc. Among them, amorphous vinyl polymerized segments obtained by polymerizing vinyl compounds are preferred, and examples thereof include acrylic acid ester polymerized segments, styrene-acrylic acid ester polymerized segments, ethylene-vinyl acetate polymerized segments, etc. These may be used alone or in combination of two or more.

[0207] Among the above vinyl polymerized segments, in consideration of the plasticity during thermal fixing, a styrene-acrylic ester polymerized segment (styrene-acrylic polymerized segment) is preferred. In addition, since the preferred form of the amorphous vinyl resin is a styrene-acrylic resin, the amorphous vinyl polymerized segment is also preferably a styrene-acrylic polymerized segment. By adopting such a form, the compatibility between the hybrid amorphous polyester resin and the amorphous vinyl resin is further improved, and the shape of the toner base particles can be easily controlled.

[0208] The monomers used to form the styrene-acrylic polymerized segment and the method of formation are the same as those described in the "styrene-acrylic polymerized segment" section of the hybrid crystalline polyester resin above, and therefore will not be described here.

[0209] The content of the amorphous polymerized segment in the hybrid amorphous polyester resin is preferably in the range of 0.1 to 50% by mass, more preferably in the range of 5 to 30% by mass, based on the total mass of the hybrid amorphous polyester resin. By being in the above range, the compatibility with the amorphous resin in the binder resin is improved, and low-temperature fixability, hot offset resistance, and heat resistance can be achieved at the same time.

[0210] The method for producing the hybrid amorphous polyester resin is not particularly limited as long as it is a method capable of forming a polymer in which the above-mentioned amorphous polyester polymerized segment and the amorphous polymerized segment are bonded together. Specific examples of the method for producing the hybrid amorphous polyester resin include the following methods.

[0211] (1) A method for producing a hybrid amorphous polyester resin by polymerizing an amorphous polymer segment in advance and then carrying out a polymerization reaction to form an amorphous polyester polymer segment in the presence of the amorphous polymer segment.

[0212] (2) A method in which an amorphous polyester polymer segment and an amorphous polymer segment are separately formed and then bonded to produce a hybrid amorphous polyester resin.

[0213] (3) A method of producing a hybrid amorphous polyester resin by forming an amorphous polyester polymer segment in advance and then carrying out a polymerization reaction to form an amorphous polymer segment in the presence of the amorphous polyester polymer segment.

[0214] Among the above formation methods (1) to (3), method (1) is preferred from the viewpoints of ease of formation of a hybrid amorphous polyester resin having a structure in which an amorphous polyester polymer segment is grafted to an amorphous polymer segment and of simplifying the production process.

[0215] Furthermore, the toner base particles may contain internal additives such as a colorant, a release agent, and a charge control agent, if necessary.

[0216] [1.3 Other ingredients] The toner base particles according to the present invention may contain, as necessary, a release agent (wax), a charge control agent, etc., in addition to the binder resin and the colorant. By containing a release agent, the releasability of the toner from a fixing member, etc. can be improved. Furthermore, by containing a charge control agent, the chargeability of the toner base particles can be adjusted.

[0217] [Release Agent] The release agent is not particularly limited, and examples thereof include hydrocarbon waxes including polyethylene wax, paraffin wax, microcrystalline wax, and Fischer-Tropsch wax, dialkyl ketone waxes including distearyl ketone, carnauba wax, montan wax, behenyl behenate, behenic acid behenate, trimethylolpropane tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, trimellitic acid tristearyl, and ester waxes including distearyl maleate, and amide waxes including ethylenediamine dibehenylamide and trimellitic acid tristearylamide. These may be used alone or in combination of two or more.

[0218] The content of the release agent is preferably within a range of 2 to 30% by mass, and more preferably within a range of 5 to 20% by mass, based on the total mass of the toner base particles. When the content of the release agent is 2% by mass or more, the toner can be sufficiently releasable from the fixing member, and when the content of the release agent is 30% by mass or less, the toner base particles can contain a sufficient amount of binder resin, and the image can be sufficiently fixed.

[0219] [Charge control agent] The charge control agent is not particularly limited, and examples thereof include nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, metal salicylate or metal complexes thereof, and the like.

[0220] From the viewpoint of the charge amount, the content of the charge control agent is preferably within a range of 0.1 to 10% by mass, and more preferably within a range of 0.5 to 5% by mass, based on the total mass of the binder resin.

[0221] [1.4 Toner base particle structure] The toner base particle according to the present invention may have a single-layer structure of only the toner base particle described above, or may have a multi-layer structure such as a core-shell structure in which the toner base particle described above is used as a core particle and the core particle is provided with a shell layer covering the surface of the core particle. The shell layer does not have to cover the entire surface of the core particle, and the core particle may be partially exposed. The cross section of the core-shell structure can be confirmed by known observation means such as a transmission electron microscope (TEM) or a scanning probe microscope (SPM).

[0222] In the case of a core-shell structure, the core particle and the shell layer can have different properties such as glass transition point, melting point, and hardness, making it possible to design toner base particles according to the purpose. For example, a shell layer can be formed by aggregating and fusing a resin with a relatively high glass transition point to the surface of a core particle with a relatively low glass transition point, which contains a binder resin, colorant, release agent, etc.

[0223] In addition, from the viewpoint of suppressing fogging, it is preferable that the release agent is not exposed on the toner particle surface and exists near the surface of the toner particle. For example, when the toner base particles contain a vinyl resin and the release agent contains an ester wax, the release agent exists near the vinyl resin, so that the vinyl resin also exists near the surface of the toner particle. That is, it is preferable that the toner contains toner base particles having a laminated structure of at least two layers (an inner layer and an outer surface layer), and the outer layer (surface layer) contains a vinyl resin and a release agent containing an ester wax. The outer layer may further contain an amorphous polyester resin as a main component. In addition, in order to further enhance the effect of the present invention, it is preferable that the domain of the vinyl resin is dispersed in the matrix of the amorphous polyester resin.

[0224] The average circularity of the toner base particles is preferably within the range of 0.935 to 0.995, more preferably within the range of 0.945 to 0.990, and even more preferably within the range of 0.955 to 0.980. By being within the above range, the individual toner particles are less likely to be crushed, the charge amount is stable, and high-quality images can be obtained. The average circularity can be measured, for example, using a flow-type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation).

[0225] Specifically, the toner base particles are wetted with a surfactant solution and dispersed by ultrasonic dispersion for one minute, and then measured using the "FPIA-2100" under the measurement conditions of HPF (high magnification imaging) mode at an appropriate concentration of 4,000 HPF detections. The circularity is calculated using the following formula. Circularity = (perimeter of a circle with the same projected area as the particle image) / (perimeter of the projected particle image) The average circularity is an arithmetic mean value obtained by adding up the circularity of each particle and dividing the total number of particles measured.

[0226] [2 External additives] The "external additive" is added from the viewpoint of improving the charging performance, fluidity, cleaning properties, etc. of the toner particles, and adheres to the surface of the toner base particles.

[0227] [2.1 Titanium dioxide] The toner according to the present invention contains titanium oxide as an external additive. By adding titanium oxide to the outside, the flowability of the toner is improved. In addition, since titanium oxide has low resistance, adding titanium oxide to the surface of the toner base particles reduces the resistance of the toner.

[0228] The content of titanium oxide is in the range of 0.01% by mass or more and less than 1.00% by mass with respect to the total mass of the toner base particles. If the content of titanium oxide is less than 0.01% by mass, the toner cannot obtain sufficient fluidity. If the content of titanium oxide is more than 1.00% by mass, the titanium oxide functions as a white pigment, and the black color development (image density) of the toner decreases.

[0229] In addition, titanium oxide is easily detached from the surface of the toner base particle due to its high density, but by making the content of titanium oxide less than 1.00% by mass relative to the total mass of the toner base particle, it is possible to suppress the decrease in charging property caused by the migration of titanium oxide to the carrier. In addition, excellent charging stability is obtained even in continuous printing with high coverage. In addition, it is possible to suppress the deterioration of cleaning property caused by excessive fluidity.

[0230] The shape of titanium oxide is not particularly limited, and the number-average particle size is preferably within the range of 10 to 50 nm, and more preferably within the range of 20 to 40 nm. By having the number-average particle size of titanium oxide within the above range, it is believed that the titanium oxide is less likely to be embedded in the toner base particles, sufficient contact points with the carrier are obtained, and migration to the carrier is also suppressed.

[0231] It is important for the titanium oxide to exist on the surface of the toner base particles and not to migrate to the carrier in order to maintain the chargeability of the developer. When the titanium oxide has a number-average particle size of 50 nm or less, when a large particle size particle is used in combination as an external additive, the large particle size particle acts as a spacer, making it difficult for the titanium oxide to separate from the toner base particles. Therefore, excellent charge build-up during continuous printing and charge stability during long-term use are obtained.

[0232] The number average particle size of titanium oxide can be measured by the following method. Using a scanning electron microscope (SEM), an image of the toner is taken at a magnification of 40,000 times. Next, the SEM image in which titanium oxide is identified is binarized and the particle size is measured. The number particle size distribution is calculated based on the particle size and number of the measured 100 primary particles.

[0233] The type of titanium oxide is not particularly limited, and hydrophobic titanium oxide that has been subjected to a surface modification treatment with a surface modification treatment agent is preferred. Hydrophobic titanium oxide can reduce the amount of moisture adsorbed, and therefore can suppress a decrease in the amount of charge in a charging environment, for example, a high-temperature and high-humidity environment.

[0234] As the surface modifying agent, a general silane coupling agent, silicone oil, fatty acid, fatty acid metal salt, etc. can be used.

[0235] Examples of the silane coupling agent include chlorosilane, alkoxysilane, silazane, and special silylating agents. Specific examples include methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N,O-( Examples of the silane derivatives include bis(trimethylsilyl)acetamide, N,N-bis(trimethylsilyl)urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane.

[0236] Specific examples of silicone oils include organosiloxane oligomers, cyclic compounds such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, tetramethylcyclotetrasiloxane, and tetravinyltetramethylcyclotetrasiloxane, and linear or branched organosiloxanes.

[0237] In addition, silicone oils having high reactivity and at least terminals modified by introducing modified groups into the side chain, one end, both ends, one end of the side chain, both ends of the side chain, etc. may be used. The types of modified groups include, but are not limited to, alkoxy, carboxy, carbinol, higher fatty acid modified, phenol, epoxy, methacryl, amino, etc. In addition, silicone oils having several types of modified groups, such as amino / alkoxy modified, may be used. Dimethyl silicone oil and these modified silicone oils, and further other surface modification treatment agents may be mixed or used together.

[0238] Examples of the surface modification treatment method include a dry method such as a spray-dry method in which a modifying treatment agent or a solution containing a modifying treatment agent is sprayed onto particles suspended in a gas phase, a wet method in which particles are immersed in a solution containing a treatment agent and then dried, and a mixing method in which the treatment agent and particles are mixed in a mixer.

[0239] Commercially available titanium oxide products include "CR-50-2" and "CR-58" (both brand names, manufactured by Ishihara Sangyo Kaisha, Ltd.).

[0240] [2.2 Other external additives] The external additive according to the present invention may be used in combination with titanium oxide and other known external additives. Examples of conventionally known external additives include particles mainly composed of inorganic materials, such as silica particles, alumina particles, zirconia particles, zinc oxide particles, chromium oxide particles, cerium oxide particles, antimony oxide particles, tungsten oxide particles, tin oxide particles, tellurium oxide particles, manganese oxide particles, boron oxide particles, and strontium titanate particles. If necessary, the particles mainly composed of these inorganic materials may be hydrophobized with a surface modifying agent such as a silane coupling agent or silicone oil. The particle diameter of these particles is preferably within the range of 20 to 500 nm, more preferably within the range of 70 to 300 nm.

[0241] Conventionally known external additives may contain particles mainly composed of organic materials including homopolymers such as styrene and methyl methacrylate, and copolymers thereof, etc. The particle diameter of these particles is preferably within the range of 10 to 1000 nm.

[0242] Furthermore, the composition may contain a lubricant such as a metal salt of a higher fatty acid. Examples of the higher fatty acid include stearic acid, oleic acid, palmitic acid, linoleic acid, and ricinoleic acid. Examples of the metal constituting the metal salt include zinc, manganese, aluminum, iron, copper, magnesium, and calcium.

[0243] The content of these external additives, in terms of the total content of the external additives together with titanium oxide, is preferably within a range of 0.05 to 5.0% by mass with respect to the total mass of the toner base particles.

[0244] [3 Toner manufacturing method] (Method of manufacturing toner base particles) The method for producing the toner base particles is not particularly limited, and examples thereof include known methods such as a kneading and pulverizing method, a suspension polymerization method, an emulsion aggregation method, a dissolution suspension method, a polyester elongation method, and a dispersion polymerization method.

[0245] Among these, it is preferable to employ the emulsion aggregation method from the viewpoints of uniformity of particle size, controllability of shape, and ease of forming a core-shell structure. The emulsion aggregation method will be described below.

[0246] <Emulsification aggregation method> The emulsion aggregation method is a method in which a dispersion of resin particles (hereinafter also referred to as "resin particles") dispersed with a surfactant or dispersion stabilizer is mixed with a dispersion of toner particle components such as colorant particles, and an aggregating agent is added to aggregate the particles to the desired toner particle size, and thereafter, or simultaneously with the aggregation, the resin particles are fused together and the shape is controlled to form toner particles.

[0247] The resin particles may be composite particles formed of two or more layers made of resins having different compositions.

[0248] The resin particles can be produced, for example, by emulsion polymerization, mini-emulsion polymerization, phase inversion emulsification, etc., or by a combination of several production methods. When an internal additive is to be contained in the resin particles, it is preferable to use the mini-emulsion polymerization method.

[0249] When an internal additive is contained in the toner base particles, the internal additive may be contained in the resin particles. Alternatively, a dispersion liquid of internal additive particles containing only the internal additive may be separately prepared, and the internal additive particles may be aggregated together with the resin particles when the resin particles are aggregated.

[0250] Also, toner base particles having a core-shell structure can be obtained by the emulsion aggregation method. Specifically, first, binder resin particles for the core part and a colorant are aggregated (and fused) to prepare granular core parts, and then binder resin particles for the shell layer are added to the dispersion liquid of the core parts, and the binder resin particles for the shell layer are aggregated and fused to the surface of the core parts to form a shell layer that covers the surface of the core parts.

[0251] The binder resin according to the present invention preferably contains a crystalline resin and an amorphous resin. In the case of producing toner base particles by the emulsion aggregation method, as an embodiment, it is preferable to include a step (1) of preparing a crystalline resin particle dispersion liquid, an amorphous resin particle dispersion liquid, and a colorant dispersion liquid as a binder resin particle dispersion liquid (hereinafter also referred to as a preparation step), and a step (2) of mixing the crystalline resin particle dispersion liquid, the amorphous resin particle dispersion liquid, and the colorant dispersion liquid, and aggregating and fusing them (hereinafter also referred to as an aggregation and fusing step).

[0252] Each step will be described in detail below.

[0253] (1) Preparation process More specifically, step (1) includes the following crystalline resin particle dispersion preparation step, amorphous resin particle dispersion preparation step, and colorant dispersion preparation step, and further includes a release agent dispersion preparation step, etc., as required.

[0254] (1-1) Crystalline resin particle dispersion preparation step and amorphous resin particle dispersion preparation step The crystalline resin particle dispersion preparation process is a process of synthesizing a crystalline resin constituting the toner base particles and dispersing the crystalline resin in particulate form in an aqueous medium to prepare a dispersion of crystalline resin particles, whereas the amorphous resin particle dispersion preparation process is a process of synthesizing an amorphous resin constituting the toner base particles and dispersing the amorphous resin in particulate form in an aqueous medium to prepare a dispersion of amorphous resin particles.

[0255] A method for dispersing a crystalline resin in an aqueous medium includes dissolving or dispersing the crystalline resin in an organic solvent (solvent) to prepare an oil phase liquid, dispersing the oil phase liquid in an aqueous medium by phase inversion emulsification or the like to form oil droplets controlled to a desired particle size, and then removing the organic solvent. The same applies to a method for dispersing an amorphous resin in an aqueous medium.

[0256] The organic solvent (solvent) used in the preparation of the oil phase liquid is preferably one having a low boiling point and low solubility in water, from the viewpoint of easy removal treatment after the formation of oil droplets, and examples thereof include methyl acetate, ethyl acetate, methyl ethyl ketone, isopropyl alcohol, methyl isobutyl ketone, toluene, xylene, etc. These may be used alone or in combination of two or more.

[0257] The amount of organic solvent (solvent) used (the total amount used when two or more types are used) is preferably within the range of 1 to 300 mass %, more preferably within the range of 10 to 200 mass %, and even more preferably within the range of 25 to 100 mass %, based on the total mass of the resin.

[0258] From the viewpoint of stable and smooth emulsification, it is necessary to make the carboxyl group in the oil phase have a proton (H + In order to promote the dissociation, it is preferable to add ammonia, sodium hydroxide, or the like to the oil phase liquid.

[0259] The amount of the aqueous medium used is preferably within a range of 50 to 2,000% by mass, more preferably within a range of 100 to 1,000% by mass, based on the total mass of the oil phase liquid. By using an amount of the aqueous medium within the above range, the oil phase liquid can be emulsified and dispersed in the aqueous medium to a desired particle size.

[0260] A dispersion stabilizer may be dissolved in the aqueous medium, and a surfactant, resin particles, etc. may be added thereto for the purpose of improving the dispersion stability of the oil droplets.

[0261] Examples of the dispersion stabilizer include inorganic compounds such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, hydroxyapatite, etc. From the viewpoint of removing the dispersion stabilizer from the obtained toner base particles, it is preferable to use one that is soluble in acid or alkali, such as tricalcium phosphate, and from the viewpoint of the environment, it is preferable to use one that is decomposable by enzymes.

[0262] Examples of the surfactant include anionic surfactants such as alkylbenzene sulfonate, α-olefin sulfonate, phosphate ester, sodium alkyldiphenyl ether disulfonate, and sodium polyoxyethylene lauryl ether sulfate; amine salt type surfactants such as alkylamine salts, aminoalcohol fatty acid derivatives, polyamine fatty acid derivatives, and imidazolines; cationic surfactants of quaternary ammonium salt type such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, and benzethonium chloride; nonionic surfactants such as fatty acid amide derivatives and polyhydric alcohol derivatives; amphoteric surfactants such as alanine, dodecyldi(aminoethyl)glycine, di(octylaminoethyl)glycine, and N-alkyl-N,N-dimethylammonium betaine; and anionic surfactants and cationic surfactants having a fluoroalkyl group can also be used.

[0263] From the viewpoint of dispersion stability, the resin particles preferably have a particle diameter within the range of 0.5 to 3 μm. Specific examples include polymethyl methacrylate resin particles having particle diameters of 1 μm and 3 μm, polystyrene resin particles having particle diameters of 0.5 μm and 2 μm, and polystyrene-acrylonitrile resin particles having a particle diameter of 1 μm.

[0264] Such emulsification and dispersion of the oil phase liquid can be carried out by utilizing mechanical energy, and the dispersing machine for carrying out the emulsification and dispersion is not particularly limited, and examples thereof include a low-speed shear type dispersing machine, a high-speed shear type dispersing machine, a friction type dispersing machine, a high-pressure jet type dispersing machine, an ultrasonic dispersing machine such as an ultrasonic homogenizer, and a high-pressure impact type dispersing machine, an ultimaizer, and the like.

[0265] The organic solvent can be removed after the formation of the oil droplets by gradually increasing the temperature of the entire dispersion in which the crystalline resin particles are dispersed in the aqueous medium while stirring, and then strongly stirring the dispersion at a certain temperature range, followed by desolvation. Alternatively, the organic solvent can be removed while reducing the pressure using an evaporator or other device. The organic solvent can also be removed from the amorphous resin microparticles after the formation of the oil droplets in the same manner as the crystalline resin particles described above.

[0266] The average particle size of the crystalline resin particles (oil droplets) or amorphous resin particles (oil droplets) in the crystalline resin particle dispersion or amorphous resin particle dispersion thus obtained is preferably within the range of 60 to 1000 nm, more preferably within the range of 80 to 500 nm. The average particle sizes of the resin particles, colorant particles, release agent, etc. can be measured with a laser diffraction / scattering type particle size distribution measuring device (Microtrack particle size distribution measuring device "UPA-150" (manufactured by Nikkiso Co., Ltd.)). The average particle size of these resin particles (oil droplets) can be controlled by the magnitude of the mechanical energy during emulsification and dispersion.

[0267] The content of the crystalline resin particles or the amorphous resin particles in the crystalline resin particle dispersion or the amorphous resin particle dispersion is preferably within a range of 10 to 50% by mass, more preferably within a range of 15 to 40% by mass, based on the total mass of the dispersion. By being within the above range, the broadening of the particle size distribution can be suppressed, and the toner properties can be improved.

[0268] (1-2) Colorant particle dispersion preparation process The colorant particle dispersion preparation step is a step of dispersing a colorant (including a pigment in the present invention) in a particulate form in an aqueous medium to prepare a pigment particle dispersion.

[0269] The aqueous medium is as described in (1-1) above, and the surfactant, resin particles, and the like described in (1-1) above may be added to this aqueous medium for the purpose of improving the dispersion stability.

[0270] The pigment can be dispersed by utilizing mechanical energy. Such a dispersing machine is not particularly limited, and as mentioned above, examples thereof include a low-speed shear type dispersing machine, a high-speed shear type dispersing machine, a friction type dispersing machine, a high-pressure jet type dispersing machine, an ultrasonic dispersing machine such as an ultrasonic homogenizer, or a high-pressure impact type dispersing machine such as an ultimizer.

[0271] From the viewpoint of dispersibility, the total content of pigment particles in the pigment particle dispersion is preferably within a range of 5 to 40 mass %, and more preferably within a range of 10 to 30 mass %, based on the total mass of the dispersion.

[0272] (1-3) Release agent particle dispersion preparation process This release agent particle dispersion preparation process is a process that is carried out as necessary when it is desired to contain a release agent in the toner base particles, and is a process in which the release agent is dispersed in particulate form in an aqueous medium to prepare a dispersion of release agent particles.

[0273] The aqueous medium is as described in (1-1) above, and from the viewpoint of dispersion stability, the aqueous medium may contain the surfactants and resin particles described in (1-1) above.

[0274] The release agent can be dispersed by utilizing mechanical energy, and the dispersing machine is not particularly limited, and examples thereof include, as mentioned above, a low-speed shear dispersing machine, a high-speed shear dispersing machine, a friction dispersing machine, a high-pressure jet dispersing machine, an ultrasonic dispersing machine such as an ultrasonic homogenizer, a high-pressure impact dispersing machine, an ultimaizer, a high-pressure homogenizer, etc. When dispersing the release agent particles, heating may be performed as necessary.

[0275] The content of the release agent particles in the release agent particle dispersion liquid is preferably within a range of 10 to 50% by mass, more preferably within a range of 15 to 40% by mass, based on the total mass of the dispersion liquid. By being within the above range, the effect of ensuring hot offset resistance and separability can be obtained.

[0276] (2) Agglomeration / fusion process Crystalline resin particle dispersion, amorphous resin particle dispersion, pigment particle dispersion, and, if necessary, other components such as release agent particle dispersion are added and mixed. Next, the particles are slowly aggregated while balancing the repulsive force of the particle surface due to pH adjustment and the aggregation force due to the aggregating agent made of an electrolyte. Then, association is performed while controlling the average particle size and particle size distribution, and at the same time, the particles are fused together by heating and stirring to control the shape, forming toner particles. This aggregation and fusion process can also be performed using mechanical energy or heating means if necessary.

[0277] In the aggregation step, first, the obtained dispersions are mixed to form a mixed liquid, which is then heated at a temperature equal to or lower than the glass transition temperature of the amorphous resin to aggregate and form aggregated particles. The aggregated particles are formed by making the pH of the mixed liquid acidic under stirring. The pH is preferably within the range of 2 to 7, more preferably within the range of 2 to 6, and even more preferably within the range of 2 to 5.

[0278] In the aggregation step, it is preferable to use an aggregating agent. The aggregating agent is not particularly limited, but a surfactant having a polarity opposite to that of the surfactant used in the dispersant, an inorganic metal salt, or a complex containing a divalent or higher metal can be suitably used.

[0279] Examples of inorganic metal salts include metal salts such as sodium chloride, potassium chloride, lithium chloride, calcium chloride, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, copper sulfate, magnesium sulfate, aluminum sulfate, manganese sulfate, and calcium nitrate, as well as inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, polyiron silica, and calcium polysulfide. Among these, aluminum salts and polyaluminum chloride are particularly preferred. In order to obtain a sharper particle size distribution, the valence of the inorganic metal salt is more preferably divalent than monovalent, more preferably trivalent than divalent, and more preferably tetravalent than trivalent.

[0280] The content of divalent or higher metal ions in the toner base particles can be controlled mainly by adjusting the pH, type, etc. of the mixture in this step.

[0281] When the aggregated particles reach the desired particle size, crystalline resin particles and / or amorphous resin particles can be added to produce a toner (particles having a core-shell structure) in which the surfaces of the core aggregated particles are coated with crystalline resin and / or amorphous resin. When adding, an aggregating agent may be added or the pH may be adjusted before the addition.

[0282] During aggregation, it is preferable to heat and increase the temperature. In this case, if the temperature reaches the fusion temperature or higher by heating and increasing the temperature, the fusion process will also proceed at the same time. The temperature increase rate is preferably within the range of 0.1 to 5°C / min. In addition, the heating temperature (peak temperature) is preferably within the range of 40 to 100°C.

[0283] The average particle size of the aggregated particles is not particularly limited, but is preferably within the range of 4.5 to 7 μm. When the aggregated particles reach a desired particle size, an aggregation terminator is added to suppress and stop the aggregation of various particles in the reaction system (hereinafter, also referred to as the aggregation termination step), thereby controlling the particle size. The aggregation terminator refers to a basic compound that can adjust the pH in a direction away from a pH environment in which the aggregation action is promoted. In the aggregation termination step, the pH of the reaction system is preferably adjusted to 5 to 9.

[0284] Examples of the flocculation stopper (basic compound) include alkali metal salts such as ethylenediaminetetraacetic acid (EDTA) and its sodium salt, gluconal, sodium gluconate, potassium citrate and sodium citrate, nitrotriacetate (NTA) salt, GLDA (commercially available L-glutamic acid-N,N-diacetic acid), humic acid and fulvic acid, maltol and ethyl maltol, pentaacetic acid and tetraacetic acid, known compounds having both functional groups of carboxyl groups and hydroxyl groups such as tetrasodium 3-hydroxy-2,2'-iminodisuccinate, or their salts or water-soluble polymers (polymer electrolytes), sodium hydroxide, potassium hydroxide, etc. In the flocculation stop step, stirring may be performed in accordance with the flocculation step.

[0285] The fusion step is a step in which, after the above-mentioned aggregation stopping step or simultaneously with the aggregation step, the reaction system is heated to a desired fusion temperature to fuse the individual particles that constitute the aggregated particles together, thereby fusing the aggregated particles to form fused particles.

[0286] The fusion temperature in the fusion step is preferably equal to or higher than the melting point of the crystalline resin, and is preferably 0 to 20° C. higher than the melting point of the crystalline resin. The heating time may be long enough to effect fusion, and may be about 0.5 to 10 hours.

[0287] In the aggregation / fusion step, in order to stably disperse each particle in the system, a surfactant having the same meaning as the surfactant used in the above (1-1) crystalline resin particle dispersion preparation step / amorphous resin particle dispersion preparation step, etc. may be added to the aqueous medium.

[0288] The addition ratio (mass ratio) of the amorphous resin particles / crystalline resin particles in the aggregation and fusion step is preferably from 1 to 100. When the ratio is within the above range, the toner has excellent hot offset resistance and low-temperature fixing ability.

[0289] In addition, when other internal additives are introduced into the toner base particles, a method is preferred in which an internal additive particle dispersion liquid containing only the internal additives is prepared, and the internal additive particle dispersion liquid is mixed with a crystalline resin particle dispersion liquid, an amorphous resin particle dispersion liquid, and a pigment dispersion liquid in the aggregation and fusion step.

[0290] After fusion, the mixture is cooled to obtain fused particles. The cooling rate is preferably 1 to 20° C. / min.

[0291] When the toner is obtained by the emulsion aggregation method, it is preferable to have a circularity control step (3) for controlling the circularity of the toner after the aggregation and fusion step.

[0292] (3) Circularity control process Specifically, the circularity control treatment may be a heat treatment in which the particles obtained in the aggregation and fusion process are heated. The circularity can be controlled by adjusting the heating temperature and holding time. By increasing the heating temperature or lengthening the holding time, the circularity can be brought closer to 1.

[0293] The heating temperature in the circularity control treatment is preferably within a range of 70 to 95° C. The circularity of particles having a particle diameter of 2 μm or more is measured using a circularity measuring device during heating, and it is possible to control the circularity by appropriately determining whether or not the circularity is as desired.

[0294] (4) Filtration and washing process The obtained dispersion of the toner base particles is cooled, and the toner base particles are separated from the dispersion using a solvent such as water, followed by a filtration process to filter out the toner base particles, and a washing process to remove any attached substances such as surfactants from the filtered toner base particles (cake-like aggregates).

[0295] The specific method of solid-liquid separation and washing is not particularly limited, and examples thereof include centrifugation, reduced pressure filtration using an aspirator, a Nutsche, etc., and filtration using a filter press, etc. In the filtration and washing steps, pH adjustment, pulverization, etc. may be carried out once or repeatedly as appropriate.

[0296] (5) Drying process The washed toner base particles are dried. The dryer used in the drying step is not particularly limited, but examples include ovens, spray dryers, vacuum freeze dryers, reduced pressure dryers, stationary shelf dryers, moving shelf dryers, fluidized bed dryers, rotary dryers, and stirring dryers. The moisture content of the dried toner base particles, as measured by Karl Fischer coulometric titration, is preferably 5% by mass or less, and more preferably 2% by mass or less.

[0297] In addition, when the dried toner base particles are aggregated by weak interparticle attractive forces to form aggregates, the aggregates may be disintegrated. The disintegration device is not particularly limited, and examples thereof include mechanical disintegration devices such as a jet mill, a Comil, a Henschel mixer, a coffee mill, and a food processor.

[0298] (External additive addition process) The toner according to the present invention is obtained by adding an external additive to the toner base particles obtained by the above-mentioned production method and allowing the additive to adhere to the surface of the toner base particles. The device for mixing the dried toner base particles with the external additive is not particularly limited, and examples thereof include various known mixing devices such as a Turbula mixer, a Henschel mixer, a Nauta mixer, a V-type mixer, a sample mill, etc. In order to set the particle size distribution of the toner in an appropriate range, sieve classification may be performed as necessary.

[0299] <Career> The carrier according to the present invention includes a core material (hereinafter also referred to as "core material particles") and a resin that coats the surface of the core material. "Coating" also includes a state in which the core material is partially coated with a resin. The layer formed by the coating resin is referred to as a "resin layer," and the resin used for coating is referred to as a "coating resin."

[0300] When the core particles are coated with resin, the toner does not scatter and a stable image density can be obtained. However, when the core particles are completely coated with resin, the core particles made of a magnetic material are not exposed, and the resistance of the carrier increases. Therefore, the carrier needs to be coated with resin so that the core particles are appropriately exposed.

[0301] Similarly, even when the material of the core particles is other than iron oxide-based, it is believed that by setting the elemental content of the main elements contained in the material of the core particles within a specific range as shown below, the core particles will be appropriately exposed on the surface of the carrier, and the same effect will be obtained.

[0302] The formula (2) shown below represents the proportion of iron (also called the "iron element content" or "iron content") among the main elements (carbon, oxygen, and iron) on the carrier surface, and by keeping this proportion within a specific range, the core particles are appropriately exposed on the carrier surface.

[0303] Formula (2) Iron element content (atomic%) = A Fe / (A C +A O +A Fe ) (However, A Fe , A C and A Orepresent the contents (atomic %) of Fe, C and O per unit area of ​​the carrier surface, respectively.

[0304] In the present invention, as shown in the above formula (1), the iron element content represented by formula (2) is characterized by being within the range of 2 to 20 atomic %. If the iron element content is less than 2 atomic %, the exposure of the core material is insufficient, so that the resistance of the carrier is high, and when used as a developer together with the toner of the present invention, the charge amount is likely to decrease over long-term use. If it exceeds 20 atomic %, the resin coating is insufficient, so that the resistance of the carrier is very low, and the toner scatters when used as a developer, and stable image density cannot be obtained.

[0305] The iron element content represented by formula (2) can be measured by the following method. In the surface elemental composition analysis by X-ray photoelectron spectroscopy (XPS), the C1s spectrum was used for carbon and the Fe2p spectrum was used for iron. 3 / 2 The spectrum for the element is measured, and the O1s spectrum for oxygen. Based on the spectrum for each of these elements, C ","A O " and "A Fe The contents (atomic %) of Fe, C and O in a unit area of ​​the carrier surface, represented as "," are determined and calculated using formula (2). The XPS measurement device used was a Thermo Fisher Scientific K-Alpha, and the measurement was performed using Al monochromatic X-rays as the X-ray source with an acceleration voltage of 7 kV and an emission current of 6 mV. The XPS measurement was performed with a vacuum of 9.0×10 -8 Once the pressure reaches mbar, the X-rays are turned on and the measurement is performed. Spot diameter: 400μm Scan count: 15 times PASS Energy: 50eV Analysis method: Smart method

[0306] The volume average particle diameter of the carrier is preferably within a range of 15 to 28 μm, and more preferably within a range of 20 to 25 μm. The volume average particle diameter of the carrier can be measured by the following method.

[0307] The volume average particle diameter of the carrier can be measured by a wet method using a laser diffraction particle size distribution analyzer "HEROS KA" (manufactured by Nippon Laser Co., Ltd.). Specifically, first, an optical system with a focal position of 200 mm is selected, and the measurement time is set to 5 seconds. Then, the sample particles to be measured are added to a 0.2 mass% sodium dodecyl sulfate aqueous solution, and dispersed for 3 minutes using an ultrasonic cleaner "US-1" (manufactured by Asone Co., Ltd.) to prepare a sample dispersion for measurement. A few drops of this are supplied to the "HEROS KA", and measurement is started when the sample concentration gauge reaches the measurable range. A cumulative distribution is created from the small diameter side for the particle size range (channel) obtained from the obtained particle size distribution, and the particle diameter at which the cumulative 50% is reached is defined as the volume average particle diameter (D50).

[0308] The core particles and coating resin constituting the carrier will be described below.

[0309] [1 Core particles] In the present invention, an iron oxide-based material (ferrite) is used for the core particles. In addition to iron oxide, magnetic metals such as copper, nickel, cobalt, or magnetic metal oxides are commonly used as core particles. It is believed that with these materials as well, effects similar to those of the present invention can be obtained by exposing the core particles appropriately on the surface of the carrier.

[0310] Ferrite has the general formula: (MO) x (Fe 2 O 3 ) y The compound that constitutes ferrite is represented by the formula: 2 O 3 The molar ratio y is preferably within a range of 30 to 95 mol %. When the molar ratio y is within the above range, the ferrite can easily obtain a desired magnetization, and the carrier particles are less likely to adhere to each other.

[0311] In the general formula, M is a metal atom, and examples of M include manganese (Mn), magnesium (Mg), strontium (Sr), calcium (Ca), titanium (Ti), copper (Cu), zinc (Zn), nickel (Ni), aluminum (Al), silicon (Si), zirconium (Zr), bismuth (Bi), cobalt (Co), and lithium (Li). These metal atoms may be used alone or in combination of two or more. Among them, from the viewpoint of obtaining low residual magnetization and suitable magnetic properties, manganese, magnesium, strontium, lithium, copper, and zinc are preferred, and manganese, magnesium, and strontium are more preferred.

[0312] That is, the core particle according to the present invention is preferably a ferrite containing at least one of manganese and magnesium, and more preferably a ferrite containing both manganese and magnesium. In the ferrite containing both manganese and magnesium, from the viewpoint of easily controlling the average magnetization to a desired range, the content of MnO is preferably within the range of 20 to 40 mol %, and more preferably within the range of 7 to 30 mol %, based on the total number of moles of the ferrite.

[0313] The core particles may be commercially available products or synthetic products.

[0314] From the viewpoint of triboelectric charging performance with the toner, the core particles preferably have a volume average particle diameter in the range of 10 to 50 μm, more preferably in the range of 20 to 40 μm. The volume average particle diameter can be measured by the method described above.

[0315] The surface shape of the core particle is not particularly limited, but it is preferable that the surface has moderate irregularities from the viewpoint of exposing the core material appropriately on the carrier surface. The degree of surface irregularities of the core particle can be judged by the value of the shape factor (SF-1).

[0316] The shape factor (SF-1) is a value calculated by the following formula: A shape factor of 100 means that the particle shape is a perfect sphere, and as the value increases, the particle surface has greater irregularities. SF-1 = (maximum length of carrier core particle) 2 / (projected area of ​​carrier core particle)×(π / 4)×100

[0317] The shape factor of the core particle can be obtained as desired by appropriately selecting the firing temperature and materials (particularly the type and composition of the metal atoms represented by the above-mentioned M), etc. The firing temperature is preferably within the range of 1000 to 2000°C, and more preferably within the range of 1000 to 1500°C. The shape factor of the core particles is preferably within a range of 110 to 150, and more preferably within a range of 120 to 140. When the shape factor is within the above range, the surface of the core particles has moderate irregularities, so that the iron content expressed by formula (2) in the resin-coated carrier can be adjusted within the above range. Note that by increasing the shape factor, the irregularities of the core particles become larger, so that the core particles become more easily exposed, and the value of the iron content expressed by formula (2) also becomes larger.

[0318] The shape factor of the core particles was measured by the following method. More than 100 randomly selected particles of the carrier core were photographed at 150x magnification using a scanning electron microscope, and the maximum length and projected area of ​​the core particles were measured using an image processing analyzer LUZEX AP (Nireco Corporation) for the photographic images captured by a scanner. "Maximum length" refers to the maximum value of the diametric length in the image of the particle. The shape factor was calculated as the average value of the shape factor SF-1 calculated by the above formula for 100 core particles.

[0319] [2 Coating resin] The structural units contained in the coating resin preferably contain structural units derived from alicyclic (meth)acrylic esters. By containing structural units derived from alicyclic (meth)acrylic ester compounds, the hydrophobicity of the resin is increased, and the amount of water adsorbed by the carrier is reduced. This makes it possible to reduce the difference in chargeability of the carrier due to environmental differences, and in particular to suppress the decrease in charge amount in a high-temperature, high-humidity environment. In addition, resins containing structural units derived from alicyclic (meth)acrylic ester compounds have the advantage of having appropriate mechanical strength, and being appropriately worn as a coating material, a new resin layer is exposed on the carrier surface, refreshing it.

[0320] Examples of the alicyclic (meth)acrylic acid ester include cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, dicyclopentanyl (meth)acrylate, cyclododecyl (meth)acrylate, methylcyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, and adamantyl (meth)acrylate. Among them, the alicyclic (meth)acrylic acid ester is preferably a (meth)acrylic acid ester having a cycloalkyl ring having 3 to 8 carbon atoms, more preferably cyclohexyl (meth)acrylate or cyclopentyl (meth)acrylate, and even more preferably cyclohexyl methacrylate from the viewpoint of mechanical strength and environmental stability of the charge amount. The alicyclic (meth)acrylic acid ester may be used alone or in combination of two or more.

[0321] As the polymerization component, in addition to the alicyclic (meth)acrylic acid ester, other monomers copolymerizable with the alicyclic (meth)acrylic acid ester may be used. Examples of other monomers include styrene compounds such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, and pn-dodecylstyrene; methacrylate ester compounds such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, benzyl methacrylate, isobornyl methacrylate, diethylaminoethyl methacrylate, and dimethylaminoethyl methacrylate; and methacrylate ester compounds such as methyl acrylate, ethyl acrylate, isopropyl acrylate, and methacrylate ester compounds. Examples of the monomers include acrylic ester compounds such as vinyl, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, and benzyl acrylate; olefin compounds such as ethylene, propylene, and isobutylene; halogenated vinyl compounds such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, and vinylidene fluoride; vinyl ester compounds such as vinyl propionate, vinyl acetate, and vinyl benzoate; vinyl ether compounds such as vinyl methyl ether and vinyl ethyl ether; vinyl ketone compounds such as vinyl methyl ketone, vinyl ethyl ketone, and vinyl hexyl ketone; N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole, and N-vinyl pyrrolidone; vinyl compounds such as vinyl naphthalene and vinyl pyridine; and acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide. These other monomers may be used alone or in combination of two or more.

[0322] Among them, from the viewpoint of mechanical strength and environmental stability of charge amount, it is preferable to use chain (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, or styrene, and it is more preferable to use chain (meth)acrylic acid esters. The number of carbon atoms in the alkyl group of the chain (meth)acrylic acid ester is preferably 1 to 8. A copolymer of an alicyclic (meth)acrylic acid ester and a chain (meth)acrylic acid ester is preferable because the carrier is easily refreshed and has excellent stress resistance in a developing machine.

[0323] The mass ratio of the alicyclic (meth)acrylic acid ester to the chain (meth)acrylic acid ester is not particularly limited, and is preferably alicyclic (meth)acrylic acid ester:chain (meth)acrylic acid ester=10:90 to 90:10 (mass ratio), and more preferably 30:70 to 70:30.

[0324] The method for producing the coating resin is not particularly limited, and any conventionally known polymerization method can be appropriately used. For example, a pulverization method, an emulsion dispersion method, a suspension polymerization method, a solution polymerization method, a dispersion polymerization method, an emulsion polymerization method, an emulsion polymerization aggregation method, and other known methods can be used. In particular, from the viewpoint of controlling the particle size, it is preferable to synthesize the resin by the emulsion polymerization method.

[0325] The polymerization initiator other than the above-mentioned monomers, the surfactant, the chain transfer agent used as necessary, and the polymerization conditions such as the polymerization temperature are not particularly limited, and any of the conventionally known polymerization initiators, surfactants, chain transfer agents, etc. can be used, and the polymerization conditions such as the polymerization temperature can be adjusted by appropriately utilizing the conventionally known polymerization conditions.

[0326] The weight-average molecular weight of the coating resin (polymer obtained by polymerizing the above-mentioned monomer) is not particularly limited, and is preferably in the range of 200,000 to 800,000, and more preferably in the range of 300,000 to 700,000. When the weight-average molecular weight of the coating resin is 200,000 or more, the wear of the resin layer formed on the surface of the core material particles is not excessively promoted, and the carriers are less likely to adhere to each other. In addition, when the weight-average molecular weight of the coating resin is 800,000 or less, the charge amount is less likely to decrease due to the migration of the external additive from the toner particles to the carrier surface, and the charge amount decrease during long-term use can be suppressed.

[0327] The weight average molecular weight of the coating resin can be measured by the above-mentioned gel permeation chromatography (GPC) method.

[0328] [3 Carrier manufacturing method] (Method of manufacturing core particles) The core particles of the carrier according to the present invention can be produced, for example, by the following method. After appropriate amounts of raw materials are weighed, they are pulverized and mixed for 0.5 hours or more, preferably 1 to 20 hours, using a ball mill or a vibration mill, etc. The pulverized material thus obtained is pelletized using a pressure molding machine, etc., and then calcined at 700 to 1200°C.

[0329] Instead of using a pressure molding machine, after pulverization, water may be added to make a slurry, and then granulated using a spray dryer. After pre-calcination, the mixture is further pulverized using a ball mill or a vibration mill, and water and, if necessary, a dispersant, binder, etc. are added to adjust the viscosity, granulated, and the oxygen concentration is controlled, and the mixture is held at 1300 to 1500°C for 1 to 24 hours for main sintering (a higher temperature is set than in the past to set the carrier core shape factor (SF-1) within the range of 110 to 150). When pulverizing after pre-calcination, water may be added and the mixture is pulverized using a wet ball mill or a wet vibration mill.

[0330] The grinding machine such as the ball mill and the vibration mill is not particularly limited, but in order to effectively and uniformly disperse the raw material, it is preferable to use fine beads having a particle size of 1 mm or less as the media to be used. The degree of grinding can be controlled by adjusting the diameter and composition of the beads to be used and the grinding time.

[0331] The fired product thus obtained is pulverized and classified by a conventional classification method such as air classification, mesh filtration, or sedimentation to adjust the particle size to a desired particle size.

[0332] Thereafter, if necessary, the surface can be heated at a low temperature to perform an oxide film treatment, and the electrical resistance can be adjusted. The oxide film treatment can be performed using a general rotary electric furnace, batch electric furnace, or the like, and heat treatment can be performed at, for example, 300 to 700°C. The thickness of the oxide film formed by this treatment is preferably within the range of 0.1 nm to 5 μm. By having a thickness of 0.1 nm or more, the effect of the oxide film layer can be fully obtained, and by having a thickness of 5 μm or less, the desired magnetization and resistance can be obtained. Furthermore, reduction may be performed before the oxide film treatment, if necessary. Note that, if the residual magnetization of the core material particles is 15 emu / g (A·m 2 / kg) or less.

[0333] (Method of forming resin layer) The carrier according to the present invention can be obtained by forming a resin layer on core particles. As a specific method for forming the resin layer, a known method can be used, for example, a wet coating method or a dry coating method. Each method will be described below, but the dry coating method is a particularly desirable method for application to the present invention and will be described in more detail. However, the coating method is not limited to the following methods.

[0334] The wet coating method includes the following. (1) Fluidized bed spray coating method For example, a coating solution prepared by dissolving a coating resin in a solvent is spray-coated onto the surface of core particles using a fluidized bed, and then dried to form a resin layer.

[0335] (2) Dip coating method In this method, core particles are immersed in a coating solution in which a coating resin is dissolved in a solvent, and then dried to form a resin layer.

[0336] (3) Polymerization method In this method, core particles are immersed in a coating solution in which a reactive compound is dissolved in a solvent, and then a resin layer is formed by polymerizing the particles by applying heat or the like.

[0337] (4) Dry Coating Method In this method, resin particles for coating are applied to the surfaces of core particles to be coated, and then a mechanical impact force is applied to melt or soften the resin particles applied to the surface of the carrier, thereby fixing the resin particles to the surface of the carrier, thereby forming a resin layer.

[0338] Specifically, a mixture of carrier core particles, resin particles, low-resistance fine particles, etc. is stirred at high speed using a high-speed stirring mixer capable of applying mechanical impact force under non-heating or heating conditions, whereby impact force is repeatedly applied to the mixture, and the resin particles, etc. are dissolved or softened and fixed to the surfaces of the core particles, thereby producing a carrier having a resin layer.

[0339] As conditions for dry coating, when heating, 80 to 130°C is preferable, and the wind speed for generating the impact force is preferably 10 m / s or more during heating and 5 m / s or less during cooling in order to suppress aggregation of the carriers. The time for applying the impact force is preferably 20 to 60 minutes.

[0340] <Two-component developer> The two-component developer of the present invention contains a toner for developing electrostatic images and a carrier. The ratio of the toner to the total mass of the toner and the carrier is not particularly limited, but is preferably within the range of 8 to 10% by mass from the viewpoints of the chargeability of the toner and high image quality at the initial stage and after continuous printing.

[0341] The two-component developer can be produced by mixing the toner and the carrier using a mixer, such as a Henschel mixer, a Nauta mixer, or a V-type mixer.

[0342] Image forming device The image forming apparatus in which the two-component developer of the present invention is preferably used will be described. For example, the image forming apparatus may be a four-cycle type image forming apparatus that is composed of four types of color developing devices, namely, yellow, magenta, cyan, and black, and one electrophotographic photoreceptor, or may be a tandem type image forming apparatus that is composed of four types of color developing devices, namely, yellow, magenta, cyan, and black, and four electrophotographic photoreceptors provided for each color.

[0343] 1 is a schematic diagram showing an example of an image forming apparatus 100 according to the present embodiment. The image forming apparatus 100 shown in FIG. 1 includes an image reading unit 110, an image processing unit 30, an image forming unit 40, a paper conveying unit 50, and a fixing device 60.

[0344] Image forming section 40 has image forming units 41Y, 41M, 41C, and 41K that form images using toner of each color, Y (yellow), M (magenta), C (cyan), and K (black). Since these all have the same configuration except for the toner contained therein, hereinafter, the symbols representing the colors may be omitted. Image forming section 40 further has an intermediate transfer unit 42 and a secondary transfer unit 43. These correspond to transfer devices.

[0345] In this embodiment, the toner according to the present invention is used as the K toner, and the two-component developer according to the present invention is used as the K developer.

[0346] The image forming unit 41 includes an exposure device 411, a development device 412, an electrophotographic photoreceptor (image carrier) 413, a charging device 414, and a drum cleaning device 415. The charging device 414 is, for example, a corona charger. The charging device 414 may be a contact charging device that charges the electrophotographic photoreceptor 413 by contacting a contact charging member such as a charging roller, a charging brush, or a charging blade with the electrophotographic photoreceptor 413. The exposure device 411 includes, for example, a semiconductor laser as a light source, and a light deflection device (polygon motor) that irradiates the electrophotographic photoreceptor 413 with laser light according to an image to be formed. The electrophotographic photoreceptor 413 is a negatively charged organic photoreceptor having photoconductivity. The electrophotographic photoreceptor 413 is charged by the charging device 414.

[0347] The developing device 412 is a two-component developing device. The developing device 412 has, for example, a developing container that contains a two-component developer, a developing roller (magnetic roller) that is rotatably arranged at the opening of the developing container, a partition that divides the inside of the developing container so that the two-component developer can communicate with each other, a transport roller for transporting the two-component developer on the opening side of the developing container toward the developing roller, and a stirring roller for stirring the two-component developer in the developing container. The developing container contains, for example, a two-component developer.

[0348] The intermediate transfer unit 42 includes an intermediate transfer belt (intermediate transfer body) 421, a primary transfer roller 422 that presses the intermediate transfer belt 421 against the electrophotographic photosensitive body 413, a plurality of support rollers 423 including a backup roller 423A, and a belt cleaning device 426. The intermediate transfer belt 421 is stretched in a loop shape around the plurality of support rollers 423. By rotating at least one drive roller among the plurality of support rollers 423, the intermediate transfer belt 421 runs at a constant speed in the direction of arrow A.

[0349] The belt cleaning device 426 has an elastic member 426a. The elastic member 426a comes into contact with the intermediate transfer belt 421 after the secondary transfer, and removes deposits on the surface of the intermediate transfer belt 421. The elastic member 426a is made of an elastic body, and includes a cleaning blade, a brush, and the like.

[0350] The secondary transfer unit 43 includes an endless secondary transfer belt 432 and a plurality of support rollers 431 including a secondary transfer roller 431A. The secondary transfer belt 432 is stretched by the secondary transfer roller 431A and the support rollers 431 in a loop shape.

[0351] Fixing device 60 has, for example, a fixing roller 62, an endless heat-generating belt 10 that covers the outer peripheral surface of fixing roller 62 and heats and melts the toner that constitutes the toner image on paper S, and a pressure roller 63 that presses paper S against fixing roller 62 and heat-generating belt 10. Paper S corresponds to a recording medium.

[0352] The image forming apparatus 100 further includes an image reading section 110, an image processing section 30, and a paper transport section 50. The image reading section 110 includes a paper feeder 111 and a scanner 112. The paper transport section 50 includes a paper feed section 51, a paper discharge section 52, and a transport path section 53. The three paper feed tray units 51a to 51c that make up the paper feed section 51 store paper S (standard paper, special paper) identified based on basis weight, size, etc., by preset type. The transport path section 53 includes a plurality of transport roller pairs, such as a registration roller pair 53a.

[0353] ≪Image forming method≫ The image forming method of the present invention is characterized by having a step of adhering the electrostatic image developing toner contained in the two-component developer of the present invention to a recording medium, and a step of fixing the adhered electrostatic image developing toner to the recording medium. The image forming method of the present invention will be described below using an image forming apparatus 100.

[0354] The scanner 112 optically scans and reads the document D on the contact glass. The reflected light from the document D is read by the CCD sensor 112a and becomes input image data. The input image data is subjected to predetermined image processing in the image processing unit 30 and sent to the exposure device 411.

[0355] Electrophotographic photoreceptor 413 rotates at a constant peripheral speed. Charging device 414 uniformly charges the surface of electrophotographic photoreceptor 413 to negative polarity. In exposure device 411, a polygon mirror of a polygon motor rotates at high speed, and laser light corresponding to input image data of each color component is developed along the axial direction of electrophotographic photoreceptor 413 and irradiated onto the outer circumferential surface of electrophotographic photoreceptor 413 along the axial direction. In this way, an electrostatic charge image is formed on the surface of electrophotographic photoreceptor 413.

[0356] In the developing device 412, the toner particles are charged by stirring and transporting the two-component developer in the developing container, and the two-component developer is transported to the developing roller, which forms a magnetic brush on the surface of the developing roller. The charged toner particles electrostatically adhere from the magnetic brush to the electrostatic charge image on the electrophotographic photoreceptor 413. In this way, the electrostatic charge image on the surface of the electrophotographic photoreceptor 413 is visualized, and a toner image corresponding to the electrostatic charge image is formed on the surface of the electrophotographic photoreceptor 413. The term "toner image" refers to a state in which toner is gathered in an image shape.

[0357] The toner image on the surface of the electrophotographic photoreceptor 413 is transferred to an intermediate transfer belt 421 by an intermediate transfer unit 42. Residual toner remaining on the surface of the electrophotographic photoreceptor 413 after the transfer is removed by a drum cleaning device 415 having a drum cleaning blade that is in sliding contact with the surface of the electrophotographic photoreceptor 413.

[0358] The intermediate transfer belt 421 is pressed against the electrophotographic photoreceptor 413 by the primary transfer roller 422, whereby a primary transfer nip is formed for each electrophotographic photoreceptor by the electrophotographic photoreceptor 413 and the intermediate transfer belt 421. In the primary transfer nip, toner images of each color are transferred to the intermediate transfer belt 421 in order, superimposed thereon.

[0359] Meanwhile, secondary transfer roller 431A is pressed against backup roller 423A via intermediate transfer belt 421 and secondary transfer belt 432. As a result, a secondary transfer nip is formed by intermediate transfer belt 421 and secondary transfer belt 432. Paper S passes through the secondary transfer nip. Paper S is transported to the secondary transfer nip by paper transport unit 50. Correction of the skew of paper S and adjustment of the transport timing are performed by a registration roller unit in which registration roller pair 53a is arranged.

[0360] When the paper S is transported to the secondary transfer nip, a transfer bias is applied to the secondary transfer roller 431A. By applying this transfer bias, the toner image carried on the intermediate transfer belt 421 is transferred to the paper S (a process of adhering the toner for developing an electrostatic image to a recording medium). The paper S to which the toner image has been transferred is transported toward the fixing device 60 by the secondary transfer belt 432.

[0361] Any deposits such as residual toner remaining on the surface of intermediate transfer belt 421 after the secondary transfer are removed by a belt cleaning device 426 having a cleaning blade that is in sliding contact with the surface of intermediate transfer belt 421. At this time, since the above-mentioned intermediate transfer body is used as the intermediate transfer belt, it is possible to reduce dynamic frictional force over time.

[0362] Fixing device 60 forms a fixing nip with heat-generating belt 10 and pressure roller 63, and heats and presses conveyed paper S in the fixing nip. In this way, the toner image is fixed to paper S (a process of fixing electrostatic image developing toner to a recording medium). Paper S with the fixed toner image is discharged outside the machine by paper discharge section 52 equipped with paper discharge rollers 52a. EXAMPLES

[0363] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. In the examples, the terms "parts" and "%" are used, but they represent "parts by mass" or "% by mass" unless otherwise specified.

[0364] Example 1 <Preparation of developer> [Toner production] [Preparation of toner base particles] <Preparation of Pigment Particle Dispersion (1)> Pigment Brown 25(PBr25): 40 parts by mass Pigment Blue 15:3(PB15:3): 25 parts by mass Pigment Violet 23 (PV23): 10 parts by mass Pigment Yellow 155(PY155): 25 parts by mass Anionic surfactant: 15 parts by mass Ion-exchanged water: 400 parts by weight

[0365] The above components were mixed and pre-dispersed for 10 minutes using a homogenizer (Ultra Turrax, manufactured by IKA Corporation), and then dispersed for 30 minutes at a pressure of 245 MPa using a high-pressure impact disperser (Ultimaizer, manufactured by Sugino Machine Co., Ltd.) to obtain an aqueous dispersion of particles containing these pigments. Ion-exchanged water was added to the obtained dispersion to adjust the solid content to 15 mass%, thereby preparing pigment particle dispersion (1). The volume-based average particle size of the pigment particles in pigment particle dispersion (1) was 150 nm. The anionic surfactant used was NEOGEN RK ("NEOGEN" is a registered trademark of Daiichi Kogyo Seiyaku Co., Ltd.) manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0366] <Preparation of Pigment Particle Dispersion (2)> Pigment particle dispersion (2) was prepared in the same manner as in the preparation of pigment particle dispersion (1) except that Pigment Brown 23 (PBr23) was used instead of Pigment Brown 25. The volume-based average particle diameter of the pigment particles in pigment particle dispersion (2) was 150 nm.

[0367] <Preparation of Pigment Particle Dispersion (3)> Pigment particle dispersion (3) was prepared in the same manner as in the preparation of pigment particle dispersion (1) except that Pigment Yellow 180 (PY180) was used instead of Pigment Yellow 155. The volume-based average particle diameter of the pigment particles in pigment particle dispersion (3) was 150 nm.

[0368] <Preparation of Pigment Particle Dispersion (4)> Pigment particle dispersion (4) was prepared in the same manner as in the preparation of pigment particle dispersion (1), except that the blending ratio of each organic pigment was changed as follows: The volume-based average particle diameter of the pigment particles in pigment particle dispersion (4) was 150 nm. Pigment Brown 25(PBr25): 60 parts by mass Pigment Blue 15:3(PB15:3): 40 parts by mass Pigment Violet 23(PV23): 0 parts by mass Pigment Yellow 155(PY155): 0 parts by mass

[0369] <Preparation of Pigment Particle Dispersion (5)> Pigment particle dispersion (5) was prepared in the same manner as in the preparation of pigment particle dispersion (1), except that the blending ratio of each organic pigment was changed as follows: The volume-based average particle diameter of the pigment particles in pigment particle dispersion (5) was 150 nm. Pigment Brown 25(PBr25): 0 parts by mass Pigment Blue 15:3(PB15:3): 85 parts by mass Pigment Violet 23(PV23): 0 parts by mass Pigment Yellow 155(PY155): 15 parts by mass

[0370] <Preparation of Pigment Particle Dispersion (6)> Pigment particle dispersion (6) was prepared in the same manner as in the preparation of pigment particle dispersion (1), except that the blending ratio of each organic pigment was changed as follows: The volume-based average particle diameter of the pigment particles in pigment particle dispersion (6) was 150 nm. Pigment Brown 25(PBr25): 0 parts by mass Pigment Blue 15:3(PB15:3): 30 parts by mass Pigment Violet 23 (PV23): 70 parts by mass Pigment Yellow 155(PY155): 0 parts by mass

[0371] <Preparation of Pigment Particle Dispersion (7)> Pigment particle dispersion (7) was prepared in the same manner as in the preparation of pigment particle dispersion (1), except that 100 parts by mass of carbon black (CB) (Regal 330, manufactured by Cabot Corporation (Regal is a registered trademark of the company)) was added instead of each organic pigment. The volume-based average particle diameter of the pigment particles in pigment particle dispersion (7) was 150 nm.

[0372] <Preparation of Pigment Particle Dispersion (8)> Pigment particle dispersion (8) was prepared in the same manner as in the preparation of pigment particle dispersion (1), except that the blending ratio of each organic pigment was changed as follows: The volume-based average particle diameter of the pigment particles in pigment particle dispersion (8) was 150 nm. Pigment Brown 25(PBr25): 55 parts by mass Pigment Blue 15:3(PB15:3): 0 parts by mass Pigment Violet 23 (PV23): 20 parts by mass Pigment Yellow 155(PY155): 25 parts by mass

[0373] <Preparation of Pigment Particle Dispersion (9)> Pigment particle dispersion (9) was prepared in the same manner as in the preparation of pigment particle dispersion (1), except that the blending ratio of each organic pigment was changed as follows. The volume-based average particle diameter of the pigment particles in pigment particle dispersion (9) was 150 nm. Carbon black (CB) used was Regal 330 manufactured by Cabot Corporation (Regal is a registered trademark of the company). Pigment Brown 25(PBr25): 40 parts by mass Pigment Blue 15:3(PB15:3): 21 parts by mass Pigment Violet 23 (PV23): 10 parts by mass Pigment Yellow 155(PY155): 20 parts by mass Carbon black (CB): 9 parts by weight

[0374] <Preparation of Pigment Particle Dispersion (10)> Pigment particle dispersion (10) was prepared in the same manner as in the preparation of pigment particle dispersion (2) except that Pigment Orange 43 (PO43) was used instead of Pigment Yellow 155. The volume-based average particle diameter of the pigment particles in pigment particle dispersion (10) was 150 nm.

[0375] <Preparation of Pigment Particle Dispersion (11)> Pigment particle dispersion (11) was prepared in the same manner as in the preparation of pigment particle dispersion (2), except that Pigment Blue 15:4 (PB15:4) was used instead of Pigment Blue 15:3. The volume-based average particle diameter of the pigment particles in pigment particle dispersion (11) was 150 nm.

[0376] <Preparation of Pigment Particle Dispersion (12)> Pigment particle dispersion (12) was prepared in the same manner as in the preparation of pigment particle dispersion (1) except that Pigment Brown 41 (PBr41) was used instead of Pigment Brown 25. The volume-based average particle diameter of the pigment particles in pigment particle dispersion (12) was 150 nm.

[0377] <Preparation of Pigment Particle Dispersion (13)> Pigment particle dispersion (13) was prepared in the same manner as in the preparation of pigment particle dispersion (2) except that Pigment Violet 19 (PV19) was used instead of Pigment Violet 23. The volume-based average particle diameter of the pigment particles in pigment particle dispersion (13) was 150 nm.

[0378] <Preparation of Pigment Particle Dispersion (14)> Pigment particle dispersion (14) was prepared in the same manner as in the preparation of pigment particle dispersion (2) except that Pigment Red 122 (PR122) was used instead of Pigment Violet 23. The volume-based average particle diameter of the pigment particles in pigment particle dispersion (14) was 150 nm.

[0379] <Preparation of Pigment Particle Dispersion (15)> Pigment particle dispersion (15) was prepared in the same manner as in the preparation of pigment particle dispersion (2) except that Pigment Red 254 (PR254) was used instead of Pigment Violet 23. The volume-based average particle diameter of the pigment particles in pigment particle dispersion (15) was 150 nm.

[0380] <Preparation of Pigment Particle Dispersion (16)> Pigment particle dispersion (16) was prepared in the same manner as in the preparation of pigment particle dispersion (2) except that Pigment Yellow 74 (PY74) was used instead of Pigment Yellow 155. The volume-based average particle diameter of the pigment particles in pigment particle dispersion (16) was 150 nm.

[0381] <Preparation of Pigment Particle Dispersion (17)> Pigment particle dispersion (17) was prepared in the same manner as in the preparation of pigment particle dispersion (2) except that Pigment Yellow 185 (PY185) was used instead of Pigment Yellow 155. The volume-based average particle diameter of the pigment particles in pigment particle dispersion (17) was 150 nm.

[0382] <Preparation of Pigment Particle Dispersion (18)> Pigment particle dispersion (18) was prepared in the same manner as in the preparation of pigment particle dispersion (2), except that the blending ratio of each organic pigment was changed as follows. The volume-based average particle diameter of the pigment particles in pigment particle dispersion (18) was 150 nm. Two types of pigments corresponding to P1-3 were used, with a total of 10 parts by mass. Pigment Brown 23(PBr23): 40 parts by mass Pigment Blue 15:3(PB15:3): 25 parts by mass Pigment Red 122 (PR122): 5 parts by mass Pigment Violet 19(PV19): 5 parts by mass Pigment Yellow 155(PY155): 25 parts by mass

[0383] The maximum absorption wavelength λmax (nm) of each pigment used in preparing the pigment particle dispersion when dispersed in methyl ethyl ketone is as shown below.

[0384] <P1-1> Pigment Yellow 74(PY74): 402nm Pigment Yellow 155(PY155): 405nm Pigment Yellow 180(PY180): 420nm Pigment Yellow 185(PY185): 402nm <P1-2> Pigment Brown 23(PBr23): 490nm Pigment Brown 25(PBr25): 490nm Pigment Brown 41(PBr41): 490nm <P1-3> Pigment Violet 19(PV19): 570nm Pigment Violet 23(PV23): 570nm Pigment Red 122(PR122): 575nm Pigment Red 254(PR254): 580nm Pigment Orange 43(PO43): 540nm <P2> Pigment Blue 15:3(PB15:3): 630nm Pigment Blue 15:4(PB15:4): 630nm

[0385] <Preparation of amorphous polyester resin particle dispersion (a1)> Bisphenol A ethylene oxide 2.2 mole adduct: 40 mole parts Bisphenol A propylene oxide 2.2 mole adduct: 60 mole parts Dimethyl terephthalate: 60 parts by mole Dimethyl fumarate: 15 mole parts Dodecenylsuccinic anhydride: 20 mole parts Trimellitic anhydride: 5 mole parts In a reaction vessel equipped with a stirrer, a thermometer, a condenser and a nitrogen gas inlet tube, the monomers other than dimethyl fumarate and trimellitic anhydride among the above monomers and tin dioctylate in an amount of 0.25 parts by mass relative to 100 parts by mass of the total of the above monomers were charged. After reacting at 235°C for 6 hours under a nitrogen gas flow, the temperature was lowered to 200°C, and the above amounts of dimethyl fumarate and trimellitic anhydride were added and reacted for 1 hour. The temperature was raised to 220°C over 5 hours, and polymerization was carried out under a pressure of 10 kPa until the desired molecular weight was reached, to obtain a pale yellow transparent amorphous polyester resin (A1). The amorphous polyester resin (A1) had a weight average molecular weight of 35,000, a number average molecular weight of 8,000 and a glass transition temperature (Tg) of 56°C.

[0386] Amorphous polyester resin (A1): 200 parts by mass Methyl ethyl ketone: 100 parts by mass Isopropyl alcohol: 35 parts by weight Ammonia aqueous solution (10% by mass): 7 parts by mass Next, the above components were placed in a separable flask, thoroughly mixed and dissolved, and then ion-exchanged water was dropped at a speed of 8 g / min using a liquid pump while heating and stirring at 40°C, and the dropping was stopped when the amount of liquid sent reached 580 parts by mass. The solvent was then removed under reduced pressure to obtain an amorphous polyester resin particle dispersion. Ion-exchanged water was added to the above dispersion to adjust the solid content to 25% by mass, thereby preparing an amorphous polyester resin particle dispersion (a1). The volume-based average particle diameter of the amorphous polyester resin (A1) in the amorphous polyester resin particle dispersion (a1) was 156 nm.

[0387] <Preparation of styrene-acrylic resin particle dispersion (b1)> A 5L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device was charged with 5 parts by mass of an anionic surfactant (Dowfax 2A1, manufactured by The Dow Chemical Company; "Dowfax" is a registered trademark of the company) and 2,500 parts by mass of ion-exchanged water, and the internal temperature was raised to 75°C while stirring at a stirring speed of 230 rpm under a nitrogen stream. Next, a solution in which 18 parts by mass of potassium persulfate (KPS) was dissolved in 342 parts by mass of ion-exchanged water was added, and the liquid temperature was raised to 75°C.

[0388] Styrene: 903 parts by weight n-Butyl acrylate: 282 parts by mass Acrylic acid: 12 parts by weight 1,10-Decanediol diacrylate: 3 parts by mass Dodecanethiol: 8 parts by mass Further, the above-mentioned monomer mixture was added dropwise over a period of 2 hours. After completion of the addition, polymerization was carried out by heating and stirring at 75°C for 2 hours to obtain an amorphous vinyl resin dispersion. Ion-exchanged water was added to the above-mentioned dispersion to adjust the solid content to 25% by mass, and a dispersion (b1) of styrene-acrylic resin (B1) particles was prepared. The volume-based average particle size of the styrene-acrylic resin (B1) was 160 nm, the weight-average molecular weight (Mw) was 38,000, the number-average molecular weight (Mn) was 15,000, and the glass transition temperature (Tg) was 52°C.

[0389] <Preparation of Crystalline Polyester Resin Particle Dispersion (c1)> Dodecanedioic acid: 50 parts by mole 1,6-Hexanediol: 50 parts by mole The monomer was placed in a reaction vessel equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas inlet tube, and the atmosphere in the reaction vessel was replaced with dry nitrogen gas. Then, titanium tetrabutoxide (Ti(On-Bu)) was added in an amount of 0.25 parts by mass relative to 100 parts by mass of the monomer. 4 ) was added. After stirring and reacting for 3 hours at 170°C under a nitrogen gas flow, the temperature was further raised to 210°C over 1 hour, the pressure inside the reaction vessel was reduced to 3 kPa, and the reaction was stirred and carried out under reduced pressure for 13 hours to obtain crystalline polyester resin (C1). The crystalline polyester resin (C1) had a weight average molecular weight of 25,000, a number average molecular weight of 8,500, and a melting point of 71.8°C.

[0390] Crystalline polyester resin (C1): 200 parts by mass Methyl ethyl ketone: 120 parts by mass Isopropyl alcohol: 30 parts by weight Next, the above components were placed in a separable flask, thoroughly mixed and dissolved at 60°C, and then 8 parts by mass of 10% by mass aqueous ammonia solution was dropped. The heating temperature was lowered to 67°C, and while stirring, ion-exchanged water was dropped at a liquid delivery rate of 8 g / min using a liquid delivery pump, and when the liquid delivery amount reached 580 parts by mass, the dropping of ion-exchanged water was stopped. Thereafter, the solvent was removed under reduced pressure to obtain a crystalline polyester resin particle dispersion. Ion-exchanged water was added to the above dispersion to adjust the solid content to 25% by mass, and a crystalline polyester resin particle dispersion (c1) was prepared. The volume-based average particle diameter of the crystalline polyester resin (C1) in the crystalline polyester resin particle dispersion (c1) was 198 nm.

[0391] <Preparation of release agent particle dispersion (W1)> Paraffin wax: 270 parts by weight Anionic surfactant: 13.5 parts by mass (60% active ingredient, 3% paraffin wax) Ion-exchanged water: 21.6 parts by mass The above components were mixed and the release agent was dissolved in a pressure discharge homogenizer (Gaulin homogenizer, manufactured by Gaulin Co., Ltd.) at an internal liquid temperature of 120°C, and then the mixture was dispersed at a dispersion pressure of 5 MPa for 120 minutes, then at 40 MPa for 360 minutes, and cooled to obtain a dispersion. Ion-exchanged water was added to adjust the solid content to 20%, to prepare a release agent particle dispersion (W1). The volume-based average particle size of the particles in the release agent particle dispersion (W1) was 215 nm. The paraffin wax used was HNP0190 (melting temperature: 85° C.) manufactured by Nippon Seiro Co., Ltd., and the anionic surfactant used was NEOGEN RK manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0392] <Preparation of toner base particles (1)> Amorphous polyester resin particle dispersion (a1): 1280 parts by mass Crystalline polyester resin particle dispersion (c1): 160 parts by mass Release agent particle dispersion (W1): 200 parts by weight Pigment particle dispersion (1): 335 parts by weight Anionic surfactant: 40 parts by mass Ion-exchanged water: 1500 parts by weight The above materials were placed in a 4-liter reaction vessel equipped with a thermometer, pH meter, and stirrer, and a 1.0% by mass aqueous solution of nitric acid was added at 25°C to adjust the pH to 3.0. Then, 100 parts by mass of a 2.0% by mass aqueous solution of aluminum sulfate (flocculant) was added over 30 minutes while dispersing at 3,000 rpm with a homogenizer (IKA Ultra Turrax T50). After the dropwise addition, the mixture was stirred for 10 minutes to thoroughly mix the raw materials and the flocculant.

[0393] Amorphous polyester resin particle dispersion (a1): 160 parts by mass Anionic surfactant: 15 parts by mass Then, a stirrer and a mantle heater were installed in the reaction vessel, and the speed of the stirrer was adjusted so that the slurry was sufficiently stirred. The temperature was raised at a rate of 0.2°C / min up to 40°C, and at a rate of 0.05°C / min after exceeding 40°C. The particle size was measured every 10 minutes using a particle size distribution measuring device (Beckman Coulter, Coulter Multisizer 3 (aperture diameter 100 μm)). When the volume-based average particle size reached 5.9 μm, the temperature was maintained, and a mixture of the above materials that had been mixed in advance was added over a period of 20 minutes. The anionic surfactant added twice was Dowfax 2A1 (20% aqueous solution) manufactured by Dow Chemical Company.

[0394] Next, after maintaining at 50°C for 30 minutes, 8 parts by mass of 20% by mass EDTA (ethylenediaminetetraacetic acid) aqueous solution was added to the reaction vessel, and then 1 mol / L of sodium hydroxide aqueous solution was added to control the pH of the raw material dispersion at 9.0. Thereafter, the temperature was increased to 85°C at a rate of 1°C / min while adjusting the pH to 9.0 every 5°C, and the temperature was maintained at 85°C.

[0395] Thereafter, when the shape factor measured using a particle size meter (FPIA-3000, manufactured by Malvern Instruments) reached 0.970, the mixture was cooled at a temperature decreasing rate of 10° C. / min to obtain a toner base particle dispersion (1).

[0396] The toner base particle dispersion (1) was filtered to obtain a solid content, which was then thoroughly washed with ion-exchanged water. The solid content was then dried at 40° C. to obtain toner base particles (1). The toner base particles (1) thus obtained had a volume-based average particle size of 6.0 μm and an average circularity of 0.972 as measured using a particle size meter (FPIA-3000, manufactured by Malvern Instruments).

[0397] <Preparation of toner base particles (2)> Styrene-acrylic resin particle dispersion (b1): 1280 parts by mass Crystalline polyester resin particle dispersion (c1): 160 parts by mass Release agent particle dispersion (W1): 200 parts by weight Pigment particle dispersion (1): 335 parts by weight Anionic surfactant: 40 parts by mass Ion-exchanged water: 1500 parts by weight The above materials were placed in a 4-liter reaction vessel equipped with a thermometer, pH meter, and stirrer, and a 1.0% by mass aqueous solution of nitric acid was added at 25°C to adjust the pH to 3.0. Then, 100 parts by mass of a 2.0% by mass aqueous solution of aluminum sulfate (flocculant) was added over 30 minutes while dispersing at 3,000 rpm with a homogenizer (IKA Ultra Turrax T50). After the dropwise addition, the mixture was stirred for 10 minutes to thoroughly mix the raw materials and the flocculant.

[0398] Amorphous polyester resin particle dispersion (a1): 160 parts by mass Anionic surfactant: 15 parts by mass Then, a stirrer and a mantle heater were installed in the reaction vessel, and the speed of the stirrer was adjusted so that the slurry was sufficiently stirred. The temperature was raised at a rate of 0.2°C / min up to 40°C, and at a rate of 0.05°C / min after exceeding 40°C. The particle size was measured every 10 minutes using a particle size distribution measuring device (Beckman Coulter, Coulter Multisizer 3 (aperture diameter 100 μm)). When the volume-based average particle size reached 5.9 μm, the temperature was maintained, and a mixture of the above materials that had been mixed in advance was added over a period of 20 minutes. The anionic surfactant added twice was Dowfax 2A1 (20% aqueous solution) manufactured by Dow Chemical Company.

[0399] Next, after maintaining at 50°C for 30 minutes, 8 parts by mass of 20% by mass EDTA (ethylenediaminetetraacetic acid) aqueous solution was added to the reaction vessel, and then 1 mol / L of sodium hydroxide aqueous solution was added to control the pH of the raw material dispersion at 9.0. Thereafter, the temperature was increased to 85°C at a rate of 1°C / min while adjusting the pH to 9.0 every 5°C, and the temperature was maintained at 85°C.

[0400] Thereafter, when the shape factor measured using a particle size meter (FPIA-3000, manufactured by Malvern Instruments) reached 0.970, the mixture was cooled at a temperature decreasing rate of 10° C. / min to obtain a toner base particle dispersion (2).

[0401] The toner base particle dispersion (2) was filtered to obtain a solid content, which was then thoroughly washed with ion-exchanged water. The solid content was then dried at 40° C. to obtain toner base particles (2). The toner base particles (2) obtained had a volume-based average particle size of 6.0 μm and an average circularity of 0.972 as measured using a particle size meter (FPIA-3000, manufactured by Malvern Instruments).

[0402] <Preparation of toner base particles (3)> Styrene-acrylic resin particle dispersion (b1): 1600 parts by mass Release agent particle dispersion (W1): 200 parts by weight Pigment particle dispersion (1): 335 parts by weight Anionic surfactant: 40 parts by mass Ion-exchanged water: 1500 parts by weight The above materials were placed in a 4-liter reaction vessel equipped with a thermometer, pH meter, and stirrer, and a 1.0% by mass aqueous solution of nitric acid was added at 25°C to adjust the pH to 3.0. Then, 100 parts by mass of a 2.0% by mass aqueous solution of aluminum sulfate (flocculant) was added over 30 minutes while dispersing at 3,000 rpm with a homogenizer (IKA Ultra Turrax T50). After the dropwise addition, the mixture was stirred for 10 minutes to thoroughly mix the raw materials and the flocculant.

[0403] Then, a stirrer and a mantle heater were installed in the reaction vessel, and the rotation speed of the stirrer was adjusted so that the slurry was sufficiently stirred. The temperature was raised at a rate of 0.2°C / min up to 40°C, and at a rate of 0.05°C / min after exceeding 40°C. The particle size was measured every 10 minutes using a particle size distribution measuring device (Beckman Coulter, Coulter Multisizer 3 (aperture diameter 100μm)). The temperature was maintained when the volume-based average particle size became 6.0μm, and then the temperature was maintained at 50°C for 30 minutes. After that, 8 parts by mass of 20% by mass EDTA (ethylenediaminetetraacetic acid) aqueous solution was added to the reaction vessel, and then 1 mol / L of sodium hydroxide aqueous solution was added to control the pH of the raw material dispersion to 9.0. Then, the temperature was raised to 90°C at a rate of 1°C / min while adjusting the pH to 9.0 every 5°C, and the temperature was maintained at 90°C. When the shape factor measured using a particle size meter (FPIA-3000, manufactured by Malvern Instruments) reached 0.970, the mixture was cooled at a temperature drop rate of 10° C. / min to obtain a toner base particle dispersion (3).

[0404] The toner base particle dispersion (3) was filtered to obtain a solid content, which was then thoroughly washed with ion-exchanged water. The solid content was then dried at 40° C. to obtain toner base particles (3). The toner base particles (3) thus obtained had a volume-based average particle size of 6.0 μm and an average circularity of 0.972 as measured using a particle size meter (FPIA-3000, manufactured by Malvern Instruments).

[0405] <Preparation of toner base particles (4)> Toner base particles (4) were obtained in the same manner as in the preparation of toner base particles (1), except that pigment particle dispersion (2) was used instead of pigment particle dispersion (1).

[0406] <Preparation of toner base particles (5)> Toner base particles (5) were obtained in the same manner as in the preparation of toner base particles (1), except that pigment particle dispersion (3) was used instead of pigment particle dispersion (1).

[0407] <Preparation of toner base particles (6)> Toner base particles (6) were obtained in the same manner as in the preparation of toner base particles (1), except that pigment particle dispersion (4) was used instead of pigment particle dispersion (1).

[0408] <Preparation of toner base particles (7)> Toner base particles (7) were obtained in the same manner as in the preparation of toner base particles (1), except that pigment particle dispersion (5) was used instead of pigment particle dispersion (1).

[0409] <Preparation of toner base particles (8)> Toner base particles (8) were obtained in the same manner as in the preparation of toner base particles (1), except that pigment particle dispersion (6) was used instead of pigment particle dispersion (1).

[0410] <Preparation of toner base particles (9)> Toner base particles (9) were obtained in the same manner as in the preparation of toner base particles (1), except that pigment particle dispersion (7) was used instead of pigment particle dispersion (1).

[0411] <Preparation of toner base particles (10)> Toner base particles (10) were obtained in the same manner as in the preparation of toner base particles (1), except that pigment particle dispersion (8) was used instead of pigment particle dispersion (1).

[0412] <Preparation of toner base particles (11)> Toner base particles (11) were obtained in the same manner as in the preparation of toner base particles (1), except that pigment particle dispersion (9) was used instead of pigment particle dispersion (1).

[0413] <Preparation of toner base particles (12)> Toner base particles (12) were obtained in the same manner as in the preparation of toner base particles (2), except that the pigment particle dispersion (10) was used instead of the pigment particle dispersion (1).

[0414] <Preparation of toner base particles (13)> Toner base particles (13) were obtained in the same manner as in the preparation of toner base particles (2), except that pigment particle dispersion (11) was used instead of pigment particle dispersion (1).

[0415] <Preparation of toner base particles (14)> Toner base particles (14) were obtained in the same manner as in the preparation of toner base particles (2), except that pigment particle dispersion (12) was used instead of pigment particle dispersion (1).

[0416] <Preparation of toner base particles (15)> Toner base particles (15) were obtained in the same manner as in the preparation of toner base particles (2), except that pigment particle dispersion (13) was used instead of pigment particle dispersion (1).

[0417] <Preparation of toner base particles (16)> Toner base particles (16) were obtained in the same manner as in the preparation of toner base particles (2), except that pigment particle dispersion (14) was used instead of pigment particle dispersion (1).

[0418] <Preparation of toner base particles (17)> Toner base particles (17) were obtained in the same manner as in the preparation of toner base particles (2), except that pigment particle dispersion (15) was used instead of pigment particle dispersion (1).

[0419] <Preparation of toner base particles (18)> Toner base particles (18) were obtained in the same manner as in the preparation of toner base particles (2), except that the pigment particle dispersion (16) was used instead of the pigment particle dispersion (1).

[0420] <Preparation of toner base particles (19)> Toner base particles (19) were obtained in the same manner as in the preparation of toner base particles (2), except that pigment particle dispersion (17) was used instead of pigment particle dispersion (1).

[0421] <Preparation of toner base particles (20)> Toner base particles (20) were obtained in the same manner as in the preparation of toner base particles (2), except that the pigment particle dispersion (18) was used instead of the pigment particle dispersion (1).

[0422] [Preparation of external additives] <Preparation of titanium oxide particles> Anatase-type titanium oxide with a number-average primary particle diameter of 30 nm was subjected to surface modification treatment with a hydrophobizing agent, isobutyltrimethoxysilane, in an aqueous wet system to obtain hydrophobic titanium oxide. The obtained hydrophobic titanium oxide was used as titanium oxide fine particles.

[0423] [Toner Preparation] <Preparation of Toner (1)> Toner base particles (1): 100 parts by weight Titanium oxide: 0.5 parts by mass Silica (number average particle size: 20 nm): 3.5 parts by mass The above materials were mixed for 20 minutes in a Henschel mixer to obtain toner (1). The number-average particle diameter of the silica particles was determined by scanning a 50,000-fold magnified SEM photograph using a scanning electron microscope (SEM) (JEM-7401F, manufactured by JEOL Ltd.), scanning the SEM photograph, binarizing the silica particles in the SEM photograph using an image processing analyzer (LUZEX AP, manufactured by Nireco Corporation), calculating the Feret's diameter in the horizontal direction for 100 silica particles, and averaging the results to obtain the number-average particle diameter.

[0424] <Preparation of toners (2) to (24)> Toners (2) to (24) were obtained by appropriately changing the type of toner base particles and the content of titanium oxide as shown in Tables I and II. Note that no titanium oxide was added to toner (23).

[0425] The contents of the pigment, carbon black and titanium oxide in the following Tables I and II represent the contents relative to the total mass of the toner base particles.

[0426] [Table 1]

[0427] [Table 2]

[0428] [Creating the carrier] [Preparation of Carrier Core Material] <Preparation of Carrier Core Material (1)> MnO: 35.0 mol% MgO: 14.5 mol% Fe 2 O 3 : 50.0 mol% SrO: 0.5 mol% The above materials were mixed with water and then milled in a wet media mill for 5 hours to obtain a slurry.

[0429] The obtained slurry was dried in a spray dryer to obtain spherical particles. After adjusting the particle size of the particles, the particles were heated at 950°C for 2 hours and pre-fired in a rotary kiln. After pulverizing in a dry ball mill for 1 hour using stainless steel beads with a diameter of 0.3 cm, polyvinyl alcohol (PVA) was added as a binder so that the solid content was 0.8 mass%, and water and a polycarboxylic acid-based dispersant were further added, and the particles were pulverized for 30 hours using zirconia beads with a diameter of 0.5 cm. The obtained powder was granulated and dried using a spray dryer, and then sintered in an electric furnace at a temperature of 1300°C for 15 hours.

[0430] The powder after firing was crushed and further classified to adjust the particle size, and then low magnetic particles were separated by magnetic separation to obtain carrier core material (1). The volume average particle size of carrier core material (1) was 30 μm and the shape factor (SF-1) was 125.

[0431] The volume average particle diameter of the carrier core material is a value obtained by measuring by a wet method using a laser diffraction type particle size distribution measuring device (HELOS KA, manufactured by Nippon Laser Co., Ltd.). Specifically, an optical system with a focal position of 200 mm was selected, and the measurement time was set to 5 seconds. Then, the carrier core material for measurement was added to a 0.2 mass % sodium dodecyl sulfate aqueous solution, and dispersed for 3 minutes using an ultrasonic cleaner (US-1, manufactured by Asone Co., Ltd.) to prepare a sample dispersion for measurement, and several drops of this were supplied to the laser diffraction type particle size distribution measuring device, and measurement was started when the sample concentration gauge reached the measurable range. A cumulative distribution was created from the small diameter side for the particle size range (channel) of the obtained particle size distribution, and the volume average particle diameter was calculated based on this.

[0432] The shape factor of the carrier core material was measured by the following method. More than 100 random particles of the carrier core material were photographed at 150x magnification using a scanning electron microscope, and the maximum length and projected area of ​​the core material particles were measured using an image processing analyzer LUZEX AP (Nireco Corporation) for the photographic images captured by a scanner. "Maximum length" refers to the maximum value of the diametric length in the image of the particle. The shape factor was calculated as the average value of the shape factor SF-1 calculated by the above formula for 100 core material particles. SF-1 = (maximum length of carrier core particle) 2 / (projected area of ​​carrier core particle)×(π / 4)×100

[0433] <Preparation of carrier core material (2)> Carrier core material (2) was obtained in the same manner as carrier core material (1) except that the firing temperature in carrier core material (1) was changed to 1100° C. The volume average particle size of carrier core material (2) was 30 μm, and SF-1 was 105.

[0434] <Preparation of Carrier Core Material (3)> Carrier core material (3) was obtained in the same manner as carrier core material (1) except that the firing temperature in carrier core material (1) was changed to 1500° C. The volume average particle size of carrier core material (3) was 30 μm and SF-1 was 145.

[0435] [Preparation of coating resin] Cyclohexyl methacrylate (CHMA) and methyl methacrylate (MMA) were added in an amount of 50:50 (copolymerization ratio) to an aqueous solution of 0.3% by mass of sodium benzenesulfonate, and potassium persulfate was added in an amount equivalent to 0.5% by mass of the total amount of monomers to carry out emulsion polymerization, followed by drying by spray drying to produce a coating resin. The weight average molecular weight of the coating resin was 500,000.

[0436] [Preparation of Carrier] <Preparation of carrier (1)> 100 parts by mass of carrier core material (1) and 3.5 parts by mass of the above coating resin were put into a high-speed stirring mixer with horizontal stirring blades, and mixed and stirred for 15 minutes at 22°C under conditions of a horizontal rotor peripheral speed of 8 m / sec, and then mixed for 50 minutes at 120°C to coat the surface of the carrier core material with the coating resin by the action of mechanical impact force (mechanochemical method), and then cooled to room temperature to obtain carrier (1). The value of the iron element content represented by the above formula (2) was 12.

[0437] <Preparation of carrier (2)> Carrier (2) was obtained in the same manner as carrier (1), except that carrier core material (1) was changed to carrier core material (2). The iron element content value represented by the above formula (2) was 2.

[0438] <Preparation of carrier (3)> Carrier (3) was obtained in the same manner as carrier (1), except that carrier core material (1) was changed to carrier core material (3). The iron element content value represented by the above formula (2) was 20.

[0439] <Preparation of carrier (4)> Carrier (4) was obtained in the same manner as carrier (1), except that the coating resin was changed to 3.5 parts by mass of methyl methacrylate (MMA). The iron content value represented by the above formula (2) was 12.

[0440] <Preparation of carrier (5)> Carrier (5) was obtained in the same manner as carrier (1), except that carrier core material (1) was changed to carrier core material (2) and the amount of coating resin added was changed to 4.0 parts by mass. The iron content value represented by the above formula (2) was 1.5.

[0441] <Preparation of carrier (6)> Carrier (6) was obtained in the same manner as carrier (1), except that carrier core material (1) was changed to carrier core material (3) and the amount of coating resin added was changed to 3.0 parts by mass. The iron content value represented by the above formula (2) was 22.

[0442] The iron content expressed by the above formula (2) was calculated by the following method. In the surface element composition analysis by X-ray photoelectron spectroscopy (XPS measurement), carbon was measured using the C1s spectrum, and iron was measured using the Fe2p 3 / 2 The spectrum for the atomic group was measured, and the O1s spectrum for oxygen was measured. Based on the spectrum for each of these atoms, C ","A O " and "A Fe The contents (number of atoms) of Fe, C and O per unit area of ​​the carrier surface, represented as "," were determined and calculated according to the above formula (2). The XPS measurement device used was K-Alpha manufactured by Thermo Fisher Scientific. The measurement was performed using Al monochromatic X-rays as the X-ray source, with the acceleration voltage set to 7 kV and the emission current set to 6 mV. The XPS measurement was performed with a vacuum of 9.0×10 -8 Once the pressure reaches mbar, the X-rays are turned on and the measurement is performed. Spot diameter: 400μm Scan count: 15 times PASS Energy: 50eV Analysis method: Smart method

[0443] [Preparation of developer] <Preparation of Developers (1) to (29)> The toner and carrier were mixed in the combinations shown in Table III using a V-type mixer (manufactured by Tokuju Machinery Co., Ltd.) at 25° C. for 30 minutes so that the toner concentration was 9% by mass, to obtain developers (1) to (29).

[0444] Evaluation The following evaluations were carried out. For image output, an evaluation device was used that had been modified so that the surface temperature of the fixing heat roller of a bizhub PRESS C1100 (manufactured by Konica Minolta, Inc.) could be changed within the range of 80 to 180° C. Each toner and each developer was filled into the toner cartridge and the developing unit of this evaluation device, respectively, to prepare an image forming device for evaluation.

[0445] (Near infrared transmittance) A4 size OK top coat + (127.9g / m 2 ) (manufactured by Oji Paper Co., Ltd.), with a toner adhesion of 4.5 g / m 2 A solid image (2cm x 2cm) was formed with the above composition, and the reflection spectrum was measured using a HITACHI U-4100 spectrophotometer with filter paper as a reference, and the reflectance was measured in the wavelength range of 800 to 1000 nm. A high reflectance means that there is almost no light absorption effect in this near-infrared region (wavelength 800 to 1000 nm), that is, near-infrared rays are transmitted with high efficiency. From the obtained reflectance, the near-infrared transmittance of each toner was evaluated according to the following criteria. ◎: Reflectance is 90% or more ○: Reflectance is 85% or more and less than 90% △: Reflectance is 80% or more and less than 85% ×: Reflectance is less than 80%

[0446] (Image Density) A4 size OK top coat + (127.9g / m 2 ) (manufactured by Oji Paper Co., Ltd.), with a toner adhesion of 4.5 g / m 2A solid image (2 cm x 2 cm) was formed, and the reflection density of the solid portion of the image was measured using a reflection densitometer (manufactured by Macbeth, RD-918). From the obtained reflection density (image density), the image density of each toner was evaluated according to the following criteria. ◎: Image density is 1.50 or more ○: Image density is 1.40 or more and less than 1.50 △: Image density is 1.30 or more and less than 1.40 ×: Image density is less than 1.30

[0447] (Charging resistance to environmental conditions) Under high temperature and humidity (HH) (30°C, 85% RH) and low temperature and humidity (LL) (10°C, 20% RH) environmental conditions, A4 size wood-free paper (65 g / m 2 A solid band-shaped image with a printing rate of 5% was formed on a 100,000-sheet toner cartridge, and the charge amount of the toner was measured after printing 100,000 sheets in each environment. The charge amount was measured by sampling the two-component developer in the developing unit and using a blow-off charge amount measuring device "TB-200" (manufactured by Toshiba Chemical Corporation). Note that a smaller difference in charge amount between the LL and HH environments means that the chargeability has better environmental condition resistance. ◎: The environmental difference Δ in toner charge is less than 8μC / g ○: The environmental difference Δ in the amount of charge of the toner is 8 μC / g or more and less than 12 μC / g. △: The environmental difference Δ in the amount of charge of the toner is 12 μC / g or more and less than 15 μC / g. ×: The environmental difference Δ in the amount of charge of the toner is 15 μC / g or more.

[0448] (Low temperature fixability) Under normal temperature and humidity (NN) (20℃, 50% RH) environmental conditions, A4 size OK top coat + (127.9g / m 2 The toner's low-temperature fixing ability was evaluated using a paper feed roller (Oji Paper Co., Ltd.). The toner adhesion amount was 10 g / m 2 A fixing experiment to fix a solid image was conducted by setting the temperature of the lower fixing roller 20°C lower than that of the upper fixing belt, and repeatedly changing the surface temperature of the upper fixing belt from 80°C to 140°C in increments of 5°C. ◎: Fixing temperature is less than 120℃ ○: Fixing temperature is 120℃ or higher and less than 135℃ △: Fixing temperature is 135℃ or higher and less than 150℃ ×: Fixing temperature is 150° C. or higher

[0449] The evaluation results are shown in Table III, where "*Resin" indicates the content of structural units derived from alicyclic (meth)acrylic acid ester relative to the total mass of the coating resin.

[0450] [Table 1]

[0451] From the above results, it is found that the two-component developer of the present invention has near-infrared transmittance, has high image density, and has excellent environmental condition resistance of charging property. It is also found that the near-infrared transmittance can be improved by appropriately selecting the pigment. Furthermore, the toner base particles contain crystalline polyester, and thus the low-temperature fixing property is improved. [Explanation of symbols]

[0452] 10 Heating Belt 30 Image processing section 40 Image forming section 41Y, 41M, 41C, 41K Image forming unit 42 Intermediate transfer unit 43 Secondary transfer unit 50 Paper transport section 51 Paper feed section 51a, 51b, 51c Paper feed tray unit 52 Paper output section 52a Paper ejection roller 53 Conveying path section 53a Registration roller pair 60 Fixing device 62 Fixing roller 63 Pressure Roller 100 Image forming device 110 Image reading unit 111 Paper feeder 112 Scanner 112a CCD sensor 411 Exposure equipment 412 Developing device 413 Electrophotographic photoreceptor 414 Charging device 415 Drum cleaning device 421 Intermediate transfer belt 422 Primary transfer roller 423, 431 Support roller 423A Backup roller 426 Belt cleaning device 426a Elastic members 431A Secondary transfer roller 432 Secondary transfer belt D Manuscript S paper

Claims

1. A two-component developer comprising an electrostatic charge image developing toner containing toner particles having toner base particles and external additives, and a carrier, wherein the toner base particles contain a colorant, the colorant contains a pigment P1 and a pigment P2, when the pigments P1 and P2 are each dispersed in methyl ethyl ketone, the absorption maximum wavelength λmax is in the range of 400 nm or more and less than 600 nm for the pigment P1, and is in the range of 600 nm or more and 700 nm or less for the pigment P2, the pigment P1 contains a pigment P1-1, a pigment P1-2, and a pigment P1-3, when the pigments P1-1, P1-2, and P1-3 are each dispersed in methyl ethyl ketone, the absorption maximum wavelength λmax is in the range of 400 nm or more and less than 460 nm for the pigment P1-1, is in the range of 460 nm or more and 530 nm or less for the pigment P1-2, and is in the range of more than 530 nm and less than 600 nm for the pigment P1-3, the external additive contains titanium oxide, the content of the titanium oxide is 0.01% by mass or more and less than 1.00% by mass based on the total mass of the toner base particles, the iron element content rate (atomic %) measured by X-ray photoelectron spectroscopy on the surface of the carrier satisfies the following formula (1) Formula (1) 2 ≤ {A Ｆｅ / (A Ｃ + A Ｏ + A Ｆｅ )} × 100 ≤ 20 (However, A Ｆｅ , A Ｃ and A Ｏ represent the contents (atomic %) of Fe, C, and O in the unit area of the carrier surface, respectively.) A two-component developer characterized by the above.

2. The pigment P1-2 contains at least one pigment selected from the group consisting of C.I. Pigment Brown 23, C.I. Pigment Brown 25, C.I. Pigment Brown 41, and C.I. Pigment Red 38 The two-component developer according to claim 1, characterized by the above.

3. The pigment P2 contains at least one pigment selected from the group consisting of C.I. Pigment Blue 15, C.I. Pigment Blue 15:1, C.I. Pigment Blue 15:2, C.I. Pigment Blue 15:3, C.I. Pigment Blue 15:4, C.I. Pigment Blue 15:5, C.I. Pigment Blue 15:6, and C.I. Pigment Blue 16 The two-component developer according to claim 1 or claim 2, characterized by the above.

4. The pigment P1-3 contains at least one kind of pigment selected from the group consisting of C.I. Pigment Orange 34, C.I. Pigment Orange 36, C.I. Pigment Orange 38, C.I. Pigment Orange 43, C.I. Pigment Orange 62, C.I. Pigment Orange 68, C.I. Pigment Orange 70, C.I. Pigment Orange 72, C.I. Pigment Orange 74, C.I. Pigment Red 31, C.I. Pigment Red 48:4, C.I. Pigment Red 57:1, C.I. Pigment Red 122, C.I. Pigment Red 146, C.I. Pigment Red 147, C.I. Pigment Red 150, C.I. Pigment Red 184, C.I. Pigment Red 238, C.I. Pigment Red 242, C.I. Pigment Red 254, C.I. Pigment Red 269, C.I. Pigment Violet 19, C.I. Pigment Violet 23, and C.I. Pigment Violet 32. The two-component developer according to any one of claims 1 to 3, characterized in that.

5. The pigment P1-1 contains at least one kind of pigment selected from the group consisting of C.I. Pigment Yellow 74, C.I. Pigment Yellow 120, C.I. Pigment Yellow 139, C.I. Pigment Yellow 151, C.I. Pigment Yellow 155, C.I. Pigment Yellow 180, C.I. Pigment Yellow 181, C.I. Pigment Yellow 185, C.I. Pigment Yellow 213, C.I. Pigment Green 7, and C.I. Pigment Green 36. The two-component developer according to any one of claims 1 to 4, characterized in that.

6. The toner base particles contain a crystalline polyester. The two-component developer according to any one of claims 1 to 5, characterized in that.

7. The carrier has a resin layer on at least the surface of the core material, and the resin contained in the resin layer contains a resin having a structural unit derived from an alicyclic (meth)acrylate. The two-component developer according to any one of claims 1 to 6, characterized in that.

8. In the resin contained in the resin layer, the content of the structural unit derived from the alicyclic (meth)acrylate is 50% by mass or more based on the total mass of the resin contained in the resin layer. The two-component developer according to claim 7, characterized in that.

9. An image forming method using a two-component developer, wherein the two-component developer according to any one of claims 1 to 8 is used as the two-component developer, a step of attaching the electrostatic charge image developing toner contained in the two-component developer to a recording medium, and a step of fixing the attached electrostatic charge image developing toner to the recording medium. The image forming method is characterized by the above.

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