JP6519537B2 - Toner for developing electrostatic latent image - Google Patents

Description

  The present invention relates to a toner for electrostatic latent image development, and more particularly to a capsule toner.

  Patent Document 1 discloses a method of forming a shell layer (coating layer) on the surface of a toner core by applying mechanical impact force or compressive shear force to polymer fine particles attached to the surface of a toner core (toner base particle). ing.

JP-A-9-179336

  However, it is difficult to provide a toner for electrostatic latent image development which is excellent in heat resistant storage stability, low temperature fixability, transferability and cleanability only by the technique disclosed in Patent Document 1.

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide a toner for developing an electrostatic latent image which is excellent in heat resistant storage stability, low temperature fixability, transferability and cleanability.

The toner for developing an electrostatic latent image according to the present invention includes a plurality of toner particles including a core containing a polyester resin and a shell layer covering the surface of the core. The shell layer includes a resin film mainly composed of an aggregate of resin particles having a glass transition temperature of 50 ° C. or more and 100 ° C. or less. The said resin particle is substantially comprised from resin which contains the repeating unit which has alcoholic hydroxyl group in the ratio of 0.5 mass% or more and 20 mass% or less. The average adhesion at a residual toner ratio of 50% by number measured by centrifugal adhesion is from 0.1 nN to 40 nN. The average transfer speed from 300 mg to 600 mg of transfer amount in the vibration transfer type flowability measurement under the condition of 1 g of toner input amount and 120 Hz of vibration frequency is 5.0 mg / s to 10 mg / s. 50% to 70% of the surface area of the toner particles in the absence of an external additive when the toner in the absence of an external additive is exposed to the vapor of a 5% by mass aqueous solution of RuO ₄ for 20 minutes Area is stained with Ru.

  According to the present invention, it is possible to provide a toner for developing an electrostatic latent image which is excellent in heat resistant storage stability, low temperature fixability, transferability and cleanability.

FIG. 2 is a view showing an example of the cross-sectional structure of toner particles (particularly, toner base particles) contained in the electrostatic latent image developing toner according to the embodiment of the present invention. FIG. 6 is a view showing a first example of a cross-sectional structure of a shell layer in the toner for developing an electrostatic latent image according to the embodiment of the present invention. FIG. 7 is a view showing a second example of the cross-sectional structure of a shell layer in the toner for developing an electrostatic latent image according to the embodiment of the present invention. It is the photograph which image | photographed the toner mother particle about the toner for electrostatic latent image development concerning embodiment of this invention using the scanning electron microscope (SEM). It is a figure for demonstrating the measuring method of Ru staining rate. It is a figure for demonstrating the adjustment method of the glass transition point (Tg) of resin which comprises a shell layer.

  Embodiments of the present invention will be described in detail. The evaluation results (values indicating the shape, physical properties, etc.) of the powder (more specifically, toner core, toner base particles, external additives, or toner, etc.) are not particularly defined, and the average value from the powder is defined. It is a number average of the value measured about each of those average particle | grains taking a considerable number of typical particle | grains.

Further, the number average particle diameter of the powder is not limited, and the number average value of the equivalent circle diameter of the primary particles (diameter of a circle having the same area as the projected area of the particles) measured using a microscope It is. In addition, if the measured value of the volume median diameter (D ₅₀ ) of the powder is not specified at all, the Coulter principle (pore electrical resistance method) using “Coulter Counter Multisizer 3” manufactured by Beckman Coulter, Inc. It is the value measured based on Also, the measurement value of circularity (= perimeter of circle equal to projected area of particle / perimeter of particle) is not specified at all, a flow type particle image analyzer (manufactured by Sysmex Corporation "FPIA (registered trademark) A number average of values measured for a considerable number of particles (e.g., 3000 particles) using -3000 "). Moreover, each measured value of an acid value and a hydroxyl value is a value measured according to "JIS (Japanese Industrial Standard) K0070-1992", if it does not prescribe at all. Moreover, each measured value of a number average molecular weight (Mn) and a mass average molecular weight (Mw) is a value measured using gel permeation chromatography, if it does not prescribe at all.

Hereinafter, “system” may be added after the compound name to generically generically refer to the compound and its derivative. When a “system” is added after the compound name to represent a polymer name, it means that the repeating unit of the polymer is derived from the compound or its derivative. Moreover, acryl and methacryl may be generically called "(meth) acryl" generically. Also, may be collectively referred to as acryloyl (CH ₂ = CH-CO-) and methacryloyl _{(CH 2 = C (CH 3} ) -CO-) comprehensively the "(meth) acryloyl". In addition, the subscript “n” of the repeating unit in each chemical formula independently indicates the number of repetitions (number of moles) of the repeating unit. N (number of repetitions) is optional unless specified.

  The toner according to the present embodiment can be suitably used, for example, as a positively chargeable toner for developing an electrostatic latent image. The toner of the present embodiment is a powder including a plurality of toner particles (particles each having a configuration to be described later). The toner may be used as a one-component developer. Further, a two-component developer may be prepared by mixing the toner and the carrier using a mixing device (more specifically, a ball mill or the like). In order to form a high quality image, it is preferable to use a ferrite carrier as a carrier. Moreover, in order to form a high quality image over a long period of time, it is preferable to use magnetic carrier particles including a carrier core and a resin layer covering the carrier core. In order to impart magnetism to the carrier particles, the carrier core may be formed of a magnetic material (for example, ferrite), or the carrier core may be formed of a resin in which magnetic particles are dispersed. In addition, magnetic particles may be dispersed in a resin layer that covers the carrier core. In order to form a high quality image, the amount of toner in the two-component developer is preferably 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the carrier. The positively chargeable toner contained in the two-component developer is positively charged by the friction with the carrier.

  The toner particles included in the toner according to the exemplary embodiment include a core (hereinafter, referred to as a toner core) and a shell layer (capsule layer) covering the surface of the toner core. The toner core contains a binder resin. In addition, the toner core may contain internal additives (for example, a colorant, a release agent, a charge control agent, and a magnetic powder). The external additive may be attached to the surface of the shell layer (or the surface area of the toner core not covered by the shell layer). If necessary, external additives may be omitted. Hereinafter, toner particles before the external additive adheres are referred to as toner base particles. Also, a material for forming a toner core is referred to as a toner core material. Moreover, the material for forming a shell layer is described as shell material.

  The toner according to the present embodiment can be used, for example, to form an image in an electrophotographic apparatus (image forming apparatus). Hereinafter, an example of an image forming method by the electrophotographic apparatus will be described.

  First, an electrostatic latent image is formed on a photosensitive member (for example, a surface layer portion of a photosensitive drum) based on image data. Next, the formed electrostatic latent image is developed using a developer containing toner. In the developing step, toner (for example, toner charged by friction with a carrier or a blade) on a developing sleeve (for example, a surface portion of a developing roller in a developing device) disposed in the vicinity of the photosensitive member is formed into an electrostatic latent image Adhere to form a toner image on the photoreceptor. Then, in the subsequent transfer step, after the toner image on the photosensitive member is transferred to the intermediate transfer member (for example, transfer belt), the toner image on the intermediate transfer member is further transferred to the recording medium (for example, paper). Thereafter, the toner is heated and pressed by a fixing device (fixing method: nip by a heating roller and a pressure roller) to fix the toner on the recording medium. As a result, an image is formed on the recording medium. For example, a full color image can be formed by superposing four color toner images of black, yellow, magenta and cyan. The transfer method may be a direct transfer method in which the toner image on the photosensitive member is directly transferred to the recording medium without passing through the intermediate transfer member. The fixing method may be a belt fixing method.

  The toner according to the present embodiment is a toner for developing an electrostatic latent image having the following configuration (hereinafter referred to as a basic configuration).

(Basic configuration of toner)
The electrostatic latent image developing toner includes a plurality of toner particles including a toner core and a shell layer. The toner core contains a polyester resin. The shell layer includes a resin film mainly composed of an assembly of resin particles having a glass transition temperature of 50 ° C. or more and 100 ° C. or less. When the resin film contains two or more types of resin particles, resin particles having a glass transition point of 50 ° C. or more and 100 ° C. or less among the resin particles (hereinafter referred to as heat-resistant particles) ). The heat-resistant particles are substantially composed of a resin containing a repeating unit having an alcoholic hydroxyl group in a proportion of 0.5% by mass or more and 20% by mass or less. The average adhesion at a residual toner ratio of 50% by number measured by centrifugal adhesion is from 0.1 nN to 40 nN. The average transfer speed from 300 mg to 600 mg of transfer amount in the vibration transfer type flowability measurement under the condition of 1 g of toner input amount and 120 Hz of vibration frequency is 5.0 mg / s to 10 mg / s. Also, when the toner without external additive is exposed for 20 minutes in the vapor of a 5 mass% RuO ₄ (ruthenium tetraoxide) aqueous solution, the toner base particles (toner particles without external additive) An area of 50% or more and 70% or less of the surface area is stained with Ru.

Hereinafter, the average adhesion at 50% by number of toner residual rate by centrifugal adhesion measurement may be described as “average adhesion F ₅₀ ”. In addition, the average transfer speed from 300 mg to 600 mg may be simply referred to as “average transfer speed” in the vibration transfer type flowability measurement under the condition of 1 g of toner input and 120 Hz of excitation frequency. . In addition, when the toner in the absence of the external additive is exposed to the vapor of a 5% by weight aqueous solution of RuO ₄ for 20 minutes, the ratio of the surface area of the toner base particle to be dyed with Ru (ruthenium) is It may be described as "staining rate". Also, resin particles constituting a resin film covering the surface of the toner core may be referred to as "shell particles".

  The toner having the above-described basic configuration is excellent in heat-resistant storage stability, low-temperature fixability, transferability, and cleanability. Hereinafter, the operation and effect of the basic configuration will be described in detail.

  In order to improve the low temperature fixability of the toner while maintaining sufficient toner durability, the Ru staining rate of the toner is 50% to 70%, and the glass transition point of the shell particles is 50 ° C. to 100 ° C. The inventor has found that the following is effective. Specifically, the surface of the toner core is covered with a resin film (hereinafter referred to as a heat resistant particle aggregate film) mainly composed of an assembly of heat resistant particles (resin particles having a glass transition temperature of 50 ° C. or more and 100 ° C. or less). It is possible to achieve both the heat resistant storage stability and the low temperature fixability of the toner. In addition, it becomes easy to impart sufficient resistance to stress in the developing device. Among the shell particles, particles of 70% by mass or more are preferably heat-resistant particles, and particles of 100% by mass are more preferably heat-resistant particles. When the glass transition point of the shell particles is too high, the assembly of shell particles becomes difficult to form into a film, and each shell particle tends to be separated.

A resin dyed with Ru when exposed to the vapor of a 5% by weight aqueous solution of RuO ₄ for 20 minutes (hereinafter referred to as Ru-dyed resin) is a noncrystalline resin (crystallized with a styrene skeleton or ethylene skeleton) (See, for example, the following document A).
Literature A: Komoto Tadashi, Rubber Association Journal, 1995, Vol. 68, No. 12

  The Ru dyed resin has a surface free energy lower than that of a toner core material (for example, a polyester resin) and tends to be susceptible to phase dislocation. By appropriately covering the surface of the toner core with the film of the above-mentioned Ru-dyeing resin, it is possible to enhance the fixing property of the toner to the recording medium (for example, paper) while securing the sufficient releasability of the toner to the heating roller of the fixing device. Becomes possible. It is considered that the adhesion between the recording medium and the toner becomes stronger due to the anchor effect of the toner on the recording medium.

  The configuration of toner particles contained in the toner having the above-described basic configuration will be described below with reference to FIGS. FIG. 1 is a view showing an example of the configuration of toner particles (particularly, toner base particles) contained in the toner according to the present embodiment. 2 and 3 are each an enlarged view of the surface of the toner base particle.

  The toner base particle 10 shown in FIG. 1 includes a toner core 11 and a shell layer 12 formed on the surface of the toner core 11. The shell layer 12 includes a resin film (specifically, a film mainly composed of an aggregate of resin particles). The shell layer 12 partially covers the surface of the toner core 11.

  For example, as shown in FIG. 2, the resin film contained in the shell layer 12 may be made only of an aggregate of the resin particles 12a in an ellipsoidal shape. The resin particles 12 a are heat-resistant particles (resin particles having a glass transition temperature of 50 ° C. or more and 100 ° C. or less). Also, the resin particles 12a are made of Ru-dyed resin.

  The resin film contained in the shell layer 12 may contain, for example, two types of resin particles 12a and 12b having different monomer compositions, as shown in FIG. For example, when the resin particles 12a are heat-resistant particles composed of Ru-dyed resin, the resin particles 12b may be heat-resistant particles or may not be heat-resistant particles. Also, the resin particles 12 b may be particles composed of Ru-dyeing resin, or may not be particles composed of Ru-dyeing resin. The shape of the resin particle 12a is, for example, an ellipsoidal shape. The shape of the resin particles 12 b may be spherical or ellipsoidal. As the resin particles 12b, for example, resin particles that are more likely to be positively charged than the resin particles 12a (heat-resistant particles) are preferable.

  In the above-described basic configuration, each method of measuring the Tg (glass transition point) of the shell particles and the Ru staining rate is the same as or a substitute for the examples described later. If the toner particles include an external additive, the external additive is removed and then the Ru staining rate is measured. As an example of the method of removing the external additive attached to the toner base particles, a method of dissolving the external additive using a solvent (more specifically, an alkaline solution etc.) or a toner using an ultrasonic cleaner There is a method of removing the external additive from the particles.

Hereinafter, the method of measuring the Ru staining rate will be described with reference to FIGS. 4 and 5. First, toner base particles (powder) are exposed to the vapor of a 5% by weight aqueous solution of RuO ₄ for 20 minutes to stain the toner base particles with Ru (ruthenium). Subsequently, the dyed toner mother particles are photographed using a scanning electron microscope (SEM) to obtain a reflection electron image of the toner mother particles as shown in FIG. 4, for example. Subsequently, image analysis of the backscattered electron image is performed using image analysis software to obtain a luminance value histogram (vertical axis: frequency (number), horizontal axis: luminance value) indicating the luminance value distribution of the image data. Specifically, waveforms L0 to L2 as shown in FIG. 5 are obtained by image analysis. In FIG. 5, the waveform L1 corresponds to a non-stained waveform showing the distribution (normal distribution) of the luminance value of the non-stained region (the region not stained with Ru) in the surface region of the toner mother particle. The waveform L2 corresponds to a staining waveform indicating the distribution (normal distribution) of the luminance value of the staining region (region stained with Ru) in the surface region of the toner mother particle. The waveform L0 corresponds to a composite waveform of the waveform L1 and the waveform L2. When the area of waveform L1 is represented by R _C and the area of waveform L2 is represented by R _S , the Ru staining rate (unit:%) is represented by the formula “Ru staining rate = 100 × R _S / (R _C + R _S )” Is represented by

  Next, with reference to FIG. 6, the adjustment method of the glass transition point (Tg) of resin which comprises shell particle | grains is demonstrated. The glass transition point (Tg) of the resin can be adjusted, for example, by changing the type or amount (blending ratio) of the components (monomers) of the resin. For example, when only the amount of n-butyl acrylate (BA) is changed among the raw material monomers used for the synthesis of the S-BA copolymer (S: styrene, BA: n-butyl acrylate), FIG. As shown in the above, it was confirmed by the inventor that the glass transition point (Tg) of the obtained resin and the BA ratio (= mass of BA / mass of all the raw material monomers) are approximately proportional to each other. Specifically, the glass transition point (Tg) of the resin tends to decrease as the BA ratio increases.

In the toner having the above-described basic configuration, the average adhesion F ₅₀ (average adhesion at 50% by number of residual toner by centrifugal adhesion measurement) is 0.1 nN to 40 nN, and the average transfer speed (toner input amount) The average transfer speed from 300 mg to 600 mg of transfer amount is 5.0 mg / sec or more and 10 mg / sec or less in the excitation transfer flowability measurement under the conditions of 1 g and an excitation frequency of 120 Hz. In order to achieve both the transferability and the cleaning properties of the toner, it is effective to set the average adhesion F ₅₀ and the average transfer speed within the above ranges (ranges defined by the above-described basic configuration). Found out. The lower the average transfer speed, the better the fluidity of the toner. However, when the average transfer speed is too low, the cleaning performance of the toner tends to deteriorate. In order to ensure sufficient toner cleaning performance, the average adhesion F ₅₀ is preferably 10 nN or more. In addition, when the average transfer speed is too high, the transferability of the toner tends to deteriorate. When the average adhesion F ₅₀ is too large, the transferability of the toner tends to be deteriorated. In addition, when the average adhesion F ₅₀ is too small, the charge rising characteristics and the cleaning property of the toner tend to be deteriorated.

In the above-described basic configuration, each measuring method of the average adhesion F ₅₀ and the average transfer speed is the same method as the embodiment described later or an alternative method thereof. The average adhesion F ₅₀ and the average transfer rate can be adjusted, for example, by changing the type of shell material, the amount added, or the film forming conditions. It is also possible to adjust the average adhesion F ₅₀ and the average transfer speed by changing the type of external additive, the amount added, or the external addition conditions. When the shell layer contains a resin film mainly composed of a collection of heat resistant particles, each of the average adhesion F ₅₀ and the average transfer speed is within the above range (the range defined by the above-described basic configuration) It is considered to be easy to adjust.

In the above basic configuration, the heat-resistant particles are preferably substantially composed of a polymer (resin) of a monomer containing one or more vinyl compounds. A polymer of a monomer containing one or more vinyl compounds has a repeating unit derived from a vinyl compound. The vinyl compound is a compound having a vinyl group (CH ₂ CHCH—) or a group in which hydrogen in the vinyl group is substituted (more specifically, ethylene, propylene, butadiene, vinyl chloride, acrylic acid, acrylic) Methyl acid, methacrylic acid, methyl methacrylate, acrylonitrile, or styrene, etc.). The vinyl compound may be addition-polymerized by the carbon double bond “C 炭素 C” contained in the above-mentioned vinyl group etc. to become a polymer (resin).

  The resin constituting the heat-resistant particles preferably has, for example, a repeating unit derived from a nitrogen-containing vinyl compound (more specifically, a quaternary ammonium compound, a pyridine compound or the like), and is represented by the following formula (1) It is particularly preferred to have a repeat unit.

In formula (1), R ¹¹ and R ¹² each independently represent a hydrogen atom, a halogen atom, or an alkyl group which may have a substituent. Also, R ³¹ , R ³² and R ³³ each independently represent a hydrogen atom, an alkyl group which may have a substituent, or an alkoxy group which may have a substituent. R ² represents an alkylene group which may have a substituent. As R ¹¹ and R ¹² , each independently, a hydrogen atom or a methyl group is preferable, and a combination in which R ¹¹ represents a hydrogen atom and R ¹² represents a hydrogen atom or a methyl group is particularly preferable. In addition, as R ³¹ , R ³² and R ³³ , each independently, an alkyl group having 1 to 8 carbon atoms is preferable, and a methyl group, an ethyl group, an n-propyl group, an iso-propyl group and an n-butyl group are preferable. Groups or iso-butyl groups are particularly preferred. As R ² , an alkylene group having 1 to 6 carbon atoms is preferable, and a methylene group or an ethylene group is particularly preferable. In the repeating units derived from 2- (methacryloyloxy) ethyltrimethylammonium chloride, R ¹¹ is a hydrogen atom, R ¹² is a methyl group, R ² is an ethylene group, and each of R ^{31 to} R ³³ is a methyl group. Respectively.

  The resin constituting the heat-resistant particles preferably has, for example, a repeating unit derived from a styrenic monomer, and particularly preferably has a repeating unit represented by the following formula (2).

In formula (2), each of R ^{41 to} R ⁴⁵ independently represents a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent Represents an aryl group which may have a group. In addition, R ⁴⁶ and R ⁴⁷ each independently represent a hydrogen atom, a halogen atom, or an alkyl group which may have a substituent. R ^{41 to} R ⁴⁵ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a carbon number (more specifically, alkoxy and alkyl A total carbon number of 2) or more and 6 or less alkoxy alkyl group is preferable. As R ⁴⁶ and R ⁴⁷ , each independently, a hydrogen atom or a methyl group is preferable, and a combination in which R ⁴⁷ represents a hydrogen atom and R ⁴⁶ represents a hydrogen atom or a methyl group is particularly preferable. In the repeating unit derived from 2- (ethoxymethyl) styrene, R ⁴¹ represents an ethoxymethyl group (C ₂ H ₅ OCH _2- ), and each of R ^{42 to} R ⁴⁷ represents a hydrogen atom.

  In order for the shell layer to have sufficiently strong hydrophobicity and appropriate strength, among the repeating units contained in the resin constituting the heat-resistant particle, the repeating unit having the highest mass ratio is a repeating unit derived from a styrenic monomer. Is preferred.

  In the toner having the above-described basic configuration, the toner core contains a polyester resin, and the heat-resistant particles are substantially constituted of a resin containing a repeating unit having an alcoholic hydroxyl group in a proportion of 0.5% by mass or more and 20% by mass or less Ru. The inventors have found that when the toner core contains a polyester resin, the resin constituting the heat-resistant particles can suppress the detachment of the shell layer from the toner particles by having an appropriate amount of a repeating unit having an alcoholic hydroxyl group. The When the amount of the repeating unit having an alcoholic hydroxyl group in the resin is too large, the water absorption of the toner particles becomes strong, the charging stability of the toner becomes worse, the adhesion of the toner particles becomes strong, and the filming There is a tendency that (a phenomenon in which a toner component or the like is fixed to the photosensitive member) tends to occur.

  It is preferable that resin which comprises heat-resistant particle | grains has a repeating unit represented, for example by following formula (3) as a repeating unit which has alcoholic hydroxyl group.

In formula (3), R ⁵¹ and R ⁵² each independently represent a hydrogen atom, a halogen atom, or an alkyl group which may have a substituent. Also, R ⁶ represents an alkylene group which may have a substituent. As R ⁵¹ and R ⁵² , each independently, a hydrogen atom or a methyl group is preferable, and a combination in which R ⁵¹ represents a hydrogen atom and R ⁵² represents a hydrogen atom or a methyl group is particularly preferable. As R ⁶ , an alkylene group having 1 to 6 carbon atoms is preferable, and an alkylene group having 1 to 4 carbon atoms is more preferable. In the repeating units derived from 2-hydroxyethyl methacrylate (HEMA), R ⁵¹ represents a hydrogen atom, R ⁵² represents a methyl group, and R ⁶ represents an ethylene group (-(CH ₂ ) _2- ). .

  In order to sufficiently suppress adsorption of moisture in the air on the surface of the shell layer while suppressing the detachment of the shell layer, the resin constituting the heat-resistant particles is, other than the repeating unit having an alcoholic hydroxyl group, It is preferable not to contain a repeating unit having at least one of an acid group, a hydroxyl group and a salt thereof.

  In order to achieve both heat resistant storage stability and low temperature fixability of the toner, the resin constituting the heat resistant particles is composed of the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), and the formula It is preferable to have at least one repeating unit selected from the group consisting of the repeating units represented by (3).

  In order to achieve both the heat resistant storage stability and the low temperature fixability of the toner, it is preferable that the resin particles are physically bonded to each other in the heat resistant particle aggregation film. By forming a portion (crush point) which is easily crushed in the film, it is possible to improve the low temperature fixability of the toner while maintaining the durability of the toner. The heat-resistant particle aggregation film having such a structure can be obtained, for example, by using resin particles as a shell material and forming a film of the material (resin particles) by dry mechanical processing.

  In order to achieve both the heat resistant storage stability and the low temperature fixability of the toner, in the toner having the above-described basic configuration, the shell layer preferably contains heat resistant particles having a circularity of 0.55 or more and 0.75 or less. When the shell layer contains heat-resistant particles having a circularity of 0.55 or more and 0.75 or less, it is considered that the film formation by the aggregation of heat-resistant particles in the shell layer is appropriately progressed. It is considered that when the film formation by the aggregation of heat-resistant particles proceeds excessively or is insufficient, sufficient heat-resistant storage stability of the toner can not be secured. In order to make the roundness of the shell particles 0.55 or more and 0.75 or less, physical force (more specifically, compressive shear force or mechanical impact) is applied to the resin particles on the toner core by mechanical processing, for example. It is preferable to apply force etc.) to bond resin particles together by physical force.

  In order to achieve both heat resistant storage stability and low temperature fixability of the toner, the glass transition point (Tg) of the binder resin mainly constituting the toner core (specifically, at a ratio of 50% by mass or more) is 20 ° C. or more It is preferable that it is 60 degrees C or less. In order to achieve both heat resistant storage stability and low temperature fixability of the toner, the softening point (Tm) of the binder resin mainly constituting the toner core (specifically, at a proportion of 50% by mass or more) is 80 ° C. or more and 145 ° C. It is preferable that it is the following. In addition, each measuring method of Tg and Tm is the same method as the Example mentioned later, or its alternative method.

In order to obtain a toner suitable for image formation, the volume median diameter (D ₅₀ ) of the toner is preferably 3 μm or more and less than 10 μm.

  Next, materials suitable for forming toner particles will be described. Resins suitable as toner core materials and shell materials are as follows.

<Suitable Thermoplastic Resin>
Preferred examples of the thermoplastic resin include styrene resin, acrylic resin (more specifically, acrylic ester polymer or methacrylic acid ester polymer, etc.), olefin resin (more specifically, polyethylene) Resin or polypropylene resin, vinyl chloride resin, polyvinyl alcohol, vinyl ether resin, N-vinyl resin, polyester resin, polyamide resin, or urethane resin. Also, a copolymer of each of these resins, that is, a copolymer in which an arbitrary repeating unit is introduced into the above resin (more specifically, a styrene-acrylic acid resin or a styrene-butadiene resin, etc.) is used. May be

  The thermoplastic resin is obtained by addition polymerization, copolymerization or condensation polymerization of one or more thermoplastic monomers. The thermoplastic monomer is a monomer that becomes a thermoplastic resin by homopolymerization (more specifically, an acrylic acid monomer, a styrenic monomer, etc.), or a monomer that becomes a thermoplastic resin by condensation polymerization (for example, by condensation polymerization) A combination of polyhydric alcohol and polyhydric carboxylic acid to be a polyester resin.

  The styrene-acrylic acid resin is a copolymer of one or more styrene monomers and one or more acrylic monomers. In order to synthesize a styrene-acrylic acid-based resin, for example, styrene-based monomers and acrylic acid-based monomers as shown below can be suitably used. A carboxyl group can be introduced into a styrene-acrylic acid resin by using an acrylic acid monomer having a carboxyl group. Further, by using a monomer having a hydroxyl group (more specifically, p-hydroxystyrene, m-hydroxystyrene, or (meth) acrylic acid hydroxyalkyl ester), the hydroxyl group can be introduced into the styrene-acrylic acid resin. . The acid value of the resulting styrene-acrylic acid resin can be adjusted by adjusting the amount of the acrylic acid monomer used. Moreover, the hydroxyl value of the styrene-acrylic acid type resin obtained can be adjusted by adjusting the usage-amount of the monomer which has a hydroxyl group.

  Preferred examples of the styrenic monomer include styrene, α-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-butylstyrene, 4-methoxystyrene, 3-hydroxystyrene, 4-hydroxystyrene, or halogenated Styrene is mentioned.

  Preferred examples of the acrylic acid-based monomer include (meth) acrylic acid, (meth) acrylic acid alkyl ester, or (meth) acrylic acid hydroxyalkyl ester. Preferred examples of (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, (meth) acrylic Examples include n-butyl acid, iso-butyl (meth) acrylate, or 2-ethylhexyl (meth) acrylate. Preferred examples of (meth) acrylic acid hydroxyalkyl ester include 2-hydroxyethyl (meth) acrylic acid, 3-hydroxypropyl (meth) acrylic acid, 2-hydroxypropyl (meth) acrylic acid, or (meth) acrylic The acid 4-hydroxybutyl is mentioned.

  The polyester resin is obtained by condensation polymerization of one or more polyhydric alcohols and one or more polyhydric carboxylic acids. As an alcohol for synthesizing a polyester resin, for example, a dihydric alcohol (more specifically, a diol or a bisphenol or the like) or a trivalent or higher alcohol can be suitably used as shown below. As a carboxylic acid for synthesizing a polyester resin, for example, a divalent carboxylic acid or a trivalent or higher carboxylic acid as shown below can be suitably used. Moreover, when synthesize | combining polyester resin, the acid value and hydroxyl value of polyester resin can be adjusted by changing the usage-amount of alcohol, and the usage-amount of carboxylic acid, respectively. When the molecular weight of the polyester resin is increased, the acid value and the hydroxyl value of the polyester resin tend to decrease.

  Preferred examples of the diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 2-butene-1,4 Diol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol or polytetramethylene glycol.

  Preferable examples of bisphenols include bisphenol A, hydrogenated bisphenol A, bisphenol A ethylene oxide adduct, or bisphenol A propylene oxide adduct.

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

  Preferred examples of the divalent carboxylic acid include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, azelaic acid, malonic acid , Succinic acid, alkylsuccinic acid (more specifically, n-butylsuccinic acid, isobutylsuccinic acid, n-octylsuccinic acid, n-dodecylsuccinic acid, or isododecylsuccinic acid, etc.), or alkenylsuccinic acid (more specifically Examples thereof include n-butenylsuccinic acid, isobutenylsuccinic acid, n-octenylsuccinic acid, n-dodecenylsuccinic acid, and isododecenylsuccinic acid).

  Preferred examples of trivalent or higher carboxylic acids include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylene carboxyl) Methane, 1,2,7,8-octane tetracarboxylic acid, pyromellitic acid, or Empol trimer acid can be mentioned.

  Next, the toner core (binder resin and internal additive), the shell layer, and the external additive will be described in order. Components (for example, internal additives or external additives) which are not necessary may be omitted depending on the use of the toner.

[Toner Core]
(Binder resin)
In the toner core, generally, the binder resin occupies most (for example, 85% by mass or more) of the components. Therefore, it is considered that the properties of the binder resin greatly affect the properties of the entire toner core. By using a plurality of resins in combination as the binder resin, the properties of the binder resin (more specifically, the hydroxyl value, acid value, Tg, Tm, etc.) can be adjusted. When the binder resin has an ester group, a hydroxyl group, an ether group, an acid group or a methyl group, the toner core tends to be anionic, and when the binder resin has an amino group or an amide group, The toner core tends to be cationic. In order to enhance the bondability (reactivity) between the toner core and the shell layer, it is preferable that at least one of the hydroxyl value and the acid value of the binder resin is 10 mg KOH / g or more.

  In order to achieve both the heat resistant storage property and the low temperature fixability of the toner, the toner core preferably contains the above-mentioned “suitable thermoplastic resin” as a binder resin, and a crystalline polyester resin and non-crystallinity It is particularly preferred to contain a polyester resin. Crystalline polyester resins have the property of melting at the glass transition point (Tg) and rapidly decreasing in viscosity when heated in the solid state. In addition, crystalline polyester resin and non-crystalline polyester resin are easily compatible with each other. In order to achieve both heat-resistant storage stability and low-temperature fixability of the toner, the toner core comprises, as a binder resin, at least one crystalline polyester resin melt-kneaded and at least one non-crystalline polyester resin. It is particularly preferable to contain.

  When a non-crystalline polyester resin is used as the binder resin of the toner core, the number average molecular weight (Mn) of the non-crystalline polyester resin is 1000 or more and 2000 or less in order to improve the strength of the toner core and the fixability of the toner. Is preferred. The molecular weight distribution (ratio Mw / Mn of mass average molecular weight (Mw) to number average molecular weight (Mn)) of the non-crystalline polyester resin is preferably 9 or more and 21 or less.

(Colorant)
The toner core may contain a colorant. As the colorant, known pigments or dyes may be used in accordance with the color of the toner. In order to form a high quality image using toner, the amount of the colorant is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the binder resin.

  The toner core may contain a black colorant. Examples of black colorants include carbon black. The black colorant may be a colorant toned to black using a yellow colorant, a magenta colorant, and a cyan colorant.

  The toner core may contain color colorants such as yellow colorants, magenta colorants, or cyan colorants.

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

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

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

(Release agent)
The toner core may contain a release agent. The release agent is used, for example, for the purpose of improving the fixing property or the offset resistance of the toner. In order to enhance the anionic property of the toner core, it is preferable to produce the toner core using an anionic wax. In order to improve the fixing property or the offset resistance of the toner, the amount of the releasing agent is preferably 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin.

  As a mold release agent, for example, low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, or aliphatic hydrocarbon wax such as Fischer-Tropsch wax; oxidized polyethylene wax or block thereof Oxides of aliphatic hydrocarbon waxes such as copolymers; vegetable waxes such as candelilla wax, carnauba wax, wax wax, jojoba wax, or rice wax; animal nature such as bees wax, lanolin or wax wax Waxes; mineral waxes such as ozokerite, ceresin, or petrolatum; waxes based on fatty acid esters such as montanic acid ester wax or castor wax; fatty acids such as deacidified carnauba wax The wax portion of the ester or the whole was deoxygenated can be suitably used. One type of release agent may be used alone, or two or more types of release agents may be used in combination.

  A compatibilizer may be added to the toner core in order to improve the compatibility between the binder resin and the release agent.

(Charge control agent)
The toner core may contain a charge control agent. The charge control agent is used, for example, for the purpose of improving the charge stability or charge rise characteristics of the toner. The charge rising characteristic of the toner is an indicator of whether or not the toner can be charged to a predetermined charge level in a short time.

  By containing a negatively chargeable charge control agent (more specifically, an organic metal complex or a chelate compound) in the toner core, the anionic property of the toner core can be enhanced. Further, the cationic property of the toner core can be enhanced by containing a positively chargeable charge control agent (more specifically, pyridine, nigrosine, quaternary ammonium salt or the like) in the toner core. However, in the case where sufficient chargeability is ensured in the toner, it is not necessary to contain the charge control agent in the toner core.

(Magnetic powder)
The toner core may contain magnetic powder. The material of the magnetic powder includes, for example, ferromagnetic metals (more specifically, iron, cobalt, nickel, alloys containing one or more of these metals, etc.), ferromagnetic metal oxides (more specifically, Ferrite, magnetite, or chromium dioxide or the like, or a material subjected to a ferromagnetic treatment (more specifically, a carbon material or the like to which ferromagnetism is imparted by heat treatment) can be suitably used. One type of magnetic powder may be used alone, or two or more types of magnetic powder may be used in combination.

  In order to suppress the elution of metal ions (for example, iron ions) from the magnetic powder, it is preferable to surface-treat the magnetic powder. In the case where a shell layer is formed on the surface of the toner core under acidic conditions, when metal ions are eluted on the surface of the toner core, the toner cores are easily fixed to each other. By suppressing the elution of metal ions from the magnetic powder, it is considered that the adhesion between toner cores can be suppressed.

[Shell layer]
The toner according to the present embodiment has the above-described basic configuration. The shell layer includes a resin film mainly composed of an assembly of heat-resistant particles (resin particles having a glass transition temperature of 50 ° C. or more and 100 ° C. or less). The resin constituting the heat-resistant particles contains one or more repeating units having an alcoholic hydroxyl group. As a monomer for introducing a repeating unit having an alcoholic hydroxyl group into the resin constituting the heat-resistant particles, (meth) acrylic acid 2-hydroxyalkyl ester is preferable, and acrylic acid 2-hydroxyethyl (HEA), acrylic acid 2-hydroxypropyl (HPA), 2-hydroxyethyl methacrylate (HEMA), or 2-hydroxypropyl methacrylate can be suitably used.

  In order to obtain a toner excellent in chargeability, heat-resistant storage stability, and low-temperature fixability, the resin constituting the heat-resistant particles comprises at least one repeating unit derived from a styrenic monomer, and (meth) acrylic acid alkyl ester. The repeating unit having the highest mass ratio among the repeating units contained in the resin constituting the heat-resistant particle, which comprises one or more repeating units derived therefrom and one or more repeating units derived from the nitrogen-containing vinyl compound, It is preferable that it is a repeating unit derived from a styrenic monomer. Preferred examples of the styrenic monomer include styrene, α-methylstyrene, 4-methylstyrene, 4-tert-butylstyrene, 4-methoxystyrene, 4-bromostyrene or 3-chlorostyrene. As (meth) acrylic acid alkyl ester, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate Or iso-butyl (meth) acrylate is preferred, and n-butyl acrylate is particularly preferred. As the nitrogen-containing vinyl compound, a (meth) acryloyl group-containing quaternary ammonium compound is particularly preferable. As the (meth) acryloyl group-containing quaternary ammonium compound, for example, (meth) acrylamidoalkyltrimethylammonium salt (more specifically, (3-acrylamidopropyl) trimethylammonium chloride etc.) or (meth) acryloyloxyalkyltrimethyl Ammonium salts (more specifically, 2- (methacryloyloxy) ethyltrimethylammonium chloride and the like) can be suitably used.

[External additive]
Inorganic particles may be attached to the surface of the toner base particles as an external additive. For example, physical stirring can be performed by stirring together toner base particles (specifically, a powder containing a plurality of toner base particles) and an external additive (specifically, a powder containing a plurality of external additive particles). The external additive adheres (physically bonds) to the surface of the toner base particles by force. The external additive is used, for example, to improve the flowability or the handleability of the toner. In order to sufficiently exhibit the function of the external additive while suppressing the detachment of the external additive from the toner particles, the amount of the external additive (when using a plurality of external additives, these external additives are used. The total amount of the agents) is preferably 0.5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the toner base particles.

  As external additive particles, inorganic particles are preferable, and particles of silica particles or metal oxides (more specifically, particles of alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, barium titanate, etc.) Particularly preferred. However, as the external additive particles, particles of an organic acid compound such as a fatty acid metal salt (more specifically, zinc stearate etc.) or resin particles may be used. Also, as the external additive particles, composite particles which are composites of plural kinds of materials may be used. One type of external additive may be used alone, or a plurality of external additives may be used in combination.

  In order to improve the flowability or handleability of the toner, it is preferable to use inorganic particles having a particle diameter of 0.005 μm or more and 1.000 μm or less as the external additive particles.

[Method of producing toner]
Hereinafter, an example of a method of producing the toner having the above-described basic configuration will be described. First, prepare the toner core. Subsequently, the toner core and the shell material are placed in the liquid. In order to form a homogeneous shell layer, it is preferable to dissolve or disperse the shell material in the liquid, for example, by stirring the liquid containing the shell material. Subsequently, the shell material is reacted in the liquid to form a shell layer (cured resin layer) on the surface of the toner core. In order to suppress the dissolution or elution of the toner core components (in particular, the binder resin and the release agent) at the time of shell layer formation, it is preferable to form the shell layer in an aqueous medium. The aqueous medium is a medium containing water as a main component (more specifically, pure water, a mixed solution of water and a polar medium, etc.). The aqueous medium may function as a solvent. The solute may be dissolved in the aqueous medium. The aqueous medium may function as a dispersion medium. The dispersoid may be dispersed in the aqueous medium. As a polar medium in an aqueous medium, for example, an alcohol (more specifically, methanol or ethanol etc.) can be used. The boiling point of the aqueous medium is about 100.degree.

  Hereinafter, the method of manufacturing the toner according to the exemplary embodiment will be further described based on more specific examples.

(Preparation of toner core)
In order to easily obtain a suitable toner core, it is preferable to produce the toner core by the aggregation method or the pulverization method, and it is more preferable to produce the toner core by the pulverization method.

  Hereinafter, an example of the pulverization method will be described. First, a binder resin and an internal additive (for example, at least one of a colorant, a release agent, a charge control agent, and magnetic powder) are mixed. Subsequently, the obtained mixture is melt-kneaded. Subsequently, the obtained melt-kneaded product is crushed and classified. As a result, a toner core having a desired particle size is obtained.

  Hereinafter, an example of the aggregation method will be described. First, these particles are coagulated to a desired particle size in an aqueous medium containing fine particles of each of a binder resin, a release agent, and a colorant. Thereby, aggregated particles including the binder resin, the release agent, and the colorant are formed. Subsequently, the obtained aggregated particles are heated to unite the components contained in the aggregated particles. As a result, a dispersion of the toner core is obtained. Thereafter, unnecessary substances (surfactants and the like) are removed from the dispersion of the toner core to obtain a toner core.

(Formation of shell layer)
An acidic substance (for example, hydrochloric acid) is added to ion exchange water to prepare an aqueous medium of weak acidity (for example, pH selected from 3 to 5). Subsequently, the toner core and the suspension of resin particles are added to the pH-adjusted aqueous medium. The suspension of resin particles corresponds to the shell material. The resin particles contained in the suspension are, for example, monomers containing one or more vinyl compounds (eg, styrene, n-butyl acrylate, 2-hydroxyethyl methacrylate, and 2- (methacryloyloxy) ethyltrimethylammonium chloride It substantially consists of a polymer of). The glass transition point of the polymer constituting the resin particles is 50 ° C. or more and 100 ° C. or less. The roundness of the resin particles contained in the suspension may exceed 0.75.

  The toner core and the like may be added to an aqueous medium at room temperature or may be added to an aqueous medium adjusted to a predetermined temperature. The appropriate addition amount of the shell material can be calculated based on the specific surface area of the toner core. In addition to the toner core and the like, a polymerization accelerator may be added to the aqueous medium.

  The resin particles (shell material) adhere to the surface of the toner core in the liquid. In order to uniformly adhere the resin particles to the surface of the toner core, it is preferable to highly disperse the toner core in a liquid containing the resin particles. In order to highly disperse the toner core in the liquid, a surfactant may be contained in the liquid, or the liquid may be stirred using a strong stirring device (for example, "Hi-bis-Disper Mix" manufactured by Primix Corporation). May be As surfactant, for example, sulfate ester salt, sulfonate, phosphate ester salt or soap can be used.

  Subsequently, while stirring the liquid containing the toner core and the resin particles, the temperature of the liquid is set at a predetermined speed (for example, a speed selected from 0.1 ° C./min to 3 ° C./min) (e.g. The temperature is raised to a temperature selected from .degree. C. to 85.degree. Furthermore, while stirring the liquid, the temperature of the liquid is kept at that temperature for a predetermined time (for example, a time selected from 30 minutes to 4 hours). As a result, a dispersion liquid of toner base particles (hereinafter referred to as particles before treatment) before mechanical processing described later is obtained.

  Subsequently, the dispersion of pre-treated particles is cooled, for example, to room temperature (about 25 ° C.). Subsequently, the dispersion of the pretreated particles is filtered, for example using a Buchner funnel. As a result, the particles before treatment are separated (solid-liquid separation) from the liquid, and wet cake-like particles before treatment are obtained. Subsequently, the obtained wet cake-like pre-treatment particles are washed. Subsequently, the washed pre-treated particles are dried.

  Subsequently, for example, using a mixer (more specifically, “Hybridization System (registered trademark)” manufactured by Nara Machinery Co., Ltd., or “Mechanofusion (registered trademark)” manufactured by Hosokawa Micron Corporation, etc.) The pre-treatment particles are mechanically treated to apply physical force to resin particles present on the surface of the toner core. Each resin particle is deformed by physical force, and the resin particles are bonded by physical force. By mechanical processing, a collection of resin particles is formed into a film on the surface of the toner core. As a result, a film having a form in which resin particles are two-dimensionally connected (a film having a granular feeling) is formed as a shell layer, and a powder of toner base particles is obtained.

  After that, if necessary, the toner base particles and the external additive are mixed using a mixer (for example, an FM mixer manufactured by Nippon Coke Industry Co., Ltd.), and the external additive is attached to the surface of the toner base particles. May be

  The contents and order of the above-described toner manufacturing method can be arbitrarily changed in accordance with the required toner configuration or characteristics. For example, when reacting a material (for example, shell material) in a liquid, after adding the material to the liquid, the material may be reacted in the liquid for a predetermined time, or the material is added to the liquid over a long time Then, the material may be reacted in the solution while adding the material to the solution. Also, the shell material may be added to the solution at one time, or may be added to the solution in multiple times. After the external addition step, the toner may be sieved. Also, unnecessary steps may be omitted. For example, when a commercially available product can be used as a material as it is, the step of preparing the material can be omitted by using the commercially available product. In addition, if the reaction for forming the shell layer proceeds well without adjusting the pH of the solution, the pH adjustment step may be omitted. Also, if an external additive is unnecessary, the external addition step may be omitted. When the external additive is not attached to the surface of the toner base particles (the external addition step is omitted), the toner base particles correspond to toner particles. As a material for synthesizing the resin, a prepolymer may be used in place of the monomer, if necessary. Moreover, in order to obtain a predetermined compound, a salt, an ester, a hydrate, or an anhydride of the compound may be used as a raw material. In order to produce the toner efficiently, it is preferable to simultaneously form a large number of toner particles. The toner particles produced simultaneously are considered to have substantially the same configuration.

  An embodiment of the present invention will be described. Table 1 shows toners TA-1 to TA-8 and TB-1 to TB-8 (toner for developing electrostatic latent image) according to Examples or Comparative Examples. Table 2 shows shell materials (suspensions A-1 to A-11) used for producing each toner shown in Table 1.

  Hereinafter, a method of manufacturing toners TA-1 to TA-8 and TB-1 to TB-8, an evaluation method, and an evaluation result will be described in order. In addition, in the evaluation which an error produces, the measurement value of a considerable number which an error becomes small enough was obtained, and the arithmetic mean of the obtained measurement value was made into the evaluation value. The measurement methods of Tg (glass transition point), Mp (melting point), and Tm (softening point) are as follows, if they are not specified at all.

<Method of measuring Tg>
A differential scanning calorimeter ("DSC-6220" manufactured by Seiko Instruments Inc.) was used as a measurement device. The Tg (glass transition point) of the sample was determined by measuring the endothermic curve of the sample using a measuring device. Specifically, about 10 mg of a sample (for example, resin) was placed in an aluminum pan (a container made of aluminum), and the aluminum pan was set in the measurement unit of the measurement apparatus. Also, an empty aluminum plate was used as a reference. In the measurement of the endothermic curve, the temperature of the measurement portion was raised from a measurement start temperature of 25 ° C. to 200 ° C. at a rate of 10 ° C./min (RUN 1). Thereafter, the temperature of the measurement unit was lowered from 200 ° C. to 25 ° C. at a rate of 10 ° C./minute. Subsequently, the temperature of the measurement unit was raised again from 25 ° C. to 200 ° C. at a rate of 10 ° C./min (RUN 2). An endothermic curve (vertical axis: heat flow (DSC signal), horizontal axis: temperature) of the sample was obtained by RUN2. The Tg of the sample was read from the endothermic curve obtained. In the endothermic curve, the temperature (onset temperature) at the change point of the specific heat (the intersection of the extrapolation line of the base line and the extrapolation line of the falling line) corresponds to the Tg (glass transition point) of the sample.

<Method of measuring Tm>
A sample (for example, resin) is set in a high-rise type flow tester ("CFT-500D" manufactured by Shimadzu Corporation), and the conditions of the die pore diameter 1 mm, plunger load 20 kg / cm ² , heating rate 6 ° C./min Then, 1 cm ³ of the sample was melted and flowed out to obtain an S-shaped curve (horizontal axis: temperature, vertical axis: stroke) of the sample. Subsequently, the Tm of the sample was read from the obtained S-shaped curve. Assuming that the maximum value of the stroke in the S-curve is S ₁ and the stroke value of the low-temperature base line is S ₂ , the temperature at which the value of the stroke in the S-curve is "(S ₁ + S ₂ ) / 2" Corresponds to the Tm (softening point) of the sample.

<Mp measurement method>
A differential scanning calorimeter ("DSC-6220" manufactured by Seiko Instruments Inc.) was used as a measurement device. The Mp (melting point) of the sample was determined by measuring the endothermic curve of the sample using a measuring device. Specifically, about 15 mg of a sample (for example, a mold release agent or resin) was placed in an aluminum pan (a container made of aluminum), and the aluminum pan was set in the measurement unit of the measurement apparatus. Also, an empty aluminum plate was used as a reference. In the measurement of the endothermic curve, the temperature of the measurement portion was raised from a measurement start temperature of 30 ° C. to 170 ° C. at a rate of 10 ° C./minute. During heating, the endothermic curve (vertical axis: heat flow (DSC signal), horizontal axis: temperature) of the sample was measured. The Mp of the sample was read from the obtained endothermic curve. In the endothermic curve, the maximum peak temperature due to the heat of fusion corresponds to the Mp (melting point) of the sample.

[Preparation of materials]
(Synthesis of crystalline polyester resin)
In a 5-L four-necked flask equipped with a thermometer (thermocouple), a dehydration tube, a nitrogen introducing tube, and a stirrer, 990 g (84 mole parts) of 1,4-butanediol, 242 g of 1,6-hexanediol (11 parts by mole), 1480 g (100 parts by mole) of fumaric acid, and 2.5 g of 1,4-benzenediol were added. Subsequently, the temperature of the contents of the flask was raised to 170 ° C. while stirring the contents of the flask, and the contents of the flask were reacted at that temperature (170 ° C.) for 5 hours. Subsequently, the contents of the flask were warmed to react at a temperature of 210 ° C. for another 1.5 hours (90 minutes). Subsequently, the contents of the flask were allowed to react for 1 hour under the conditions of a reduced pressure atmosphere (pressure 8 kPa) and a temperature of 210.degree.

  Subsequently, the inside of the flask was returned to the normal pressure atmosphere, and 69 g (2.8 mole parts) of styrene and 54 g (2.2 mole parts) of n-butyl methacrylate were placed in the flask. Subsequently, the contents of the flask were warmed and reacted at a temperature of 210 ° C. for 1.5 hours (90 minutes). Subsequently, the contents of the flask were allowed to react for 1 hour under the conditions of a reduced pressure atmosphere (pressure 8 kPa) and a temperature of 210.degree. As a result, Tm (softening point) 88.8 ° C., Mp (melting point) 82 ° C., acid value 3.1 mg KOH / g, hydroxyl value 19 mg KOH / g, Mw (mass average molecular weight) 27500, Mn (number average molecular weight) 3620 A crystalline polyester resin was obtained.

(Synthesis of non-crystalline polyester resin)
In a 5-L four-necked flask equipped with a thermometer (thermocouple), a dehydration pipe, a nitrogen introduction pipe, and a stirrer, 1700 g of bisphenol A propylene oxide adduct, 650 g of bisphenol A ethylene oxide adduct, and n- 500 g of dodecenyl succinic anhydride, 400 g of terephthalic acid and 4 g of dibutyltin oxide were added. Subsequently, the contents of the flask were reacted at a temperature of 220 ° C. for 9 hours. Subsequently, the contents of the flask were reacted in a reduced pressure atmosphere (pressure 8.3 kPa) until the Tm of the reaction product (resin) reached a predetermined temperature (124.8 ° C.). As a result, Tm (softening point) 124.8 ° C., Tg (glass transition point) 57.2 ° C., acid value 6 mg KOH / g, hydroxyl value 41 mg KOH / g, Mw (mass average molecular weight) 109475, Mn (number average molecular weight) 3737 amorphous polyester resin was obtained.

(Shell material: Preparation of suspensions A-1 to A-11)
A 1 L three-necked flask equipped with a thermometer and a stirring blade is set in a water bath at a temperature of 30 ° C., and 875 mL of ion-exchanged water and an anionic surfactant (Lateomu (registered trademark of Kao Corp.) (registered trademark) in the flask. ) WX ", component: sodium polyoxyethylene alkyl ether sulfate, solid content concentration: 26% by mass) and 75 mL. Thereafter, the temperature in the flask was raised to 80 ° C. using a water bath. Subsequently, two kinds of liquids (the first liquid and the second liquid) were dropped into the flask contents at 80 ° C. for 5 hours.

  The first liquid was a mixed liquid of the monomers shown in Table 2 (S, BA, METAC, and a monomer having an alcoholic hydroxyl group). In Table 2, "S" is styrene, "BA" is n-butyl acrylate, "METAC" is 2- (methacryloyloxy) ethyl trimethyl ammonium chloride (manufactured by Alfa Aesar), and "HEMA" is methacrylic acid. "HEA" shows 2-hydroxyethyl acrylate and "HPA" shows 2-hydroxypropyl acrylate, respectively. For example, in the preparation of the suspension A-1, the first solution contains 18 g of styrene (S), 2 g of n-butyl acrylate (BA), and 0.5 g of 2- (methacryloyloxy) ethyltrimethylammonium chloride (METAC) And a mixture of 0.103 g of 2-hydroxyethyl methacrylate (HEMA). The amount of the monomer having an alcoholic hydroxyl group (HEMA, HEA or HPA) is such that the proportion of repeating units (repeating units having an alcoholic hydroxyl group) derived from the monomer in the resin produced by the polymerization reaction described later The ratio (unit: mass%) shown in 2 was determined. The proportion of the repeating unit having an alcoholic hydroxyl group in the resin can be represented by the formula “100 × mass of monomer having alcoholic hydroxyl group / mass of all monomer starting materials”. The proportion (0.5% by mass) of the repeating unit having an alcoholic hydroxyl group in the resin constituting the resin particles contained in the suspension A-1 is “100 × 0.103 / (18 + 2 + 0.5 + 0.103) = 0 Calculated as “5”.

  The second liquid was a solution in which 0.5 g of potassium persulfate was dissolved in 30 mL of ion exchanged water.

  Subsequently, the temperature in the flask was kept at 80 ° C. for another 2 hours to polymerize the contents of the flask. As a result, suspensions A-1 to A-11 of resin fine particles were obtained.

  The number average primary particle diameter and the glass transition point (Tg) of the resin fine particles contained in each of the suspensions A-1 to A-11 prepared as described above were as shown in Table 2. In Table 2, "particle size" means the number average primary particle size. A transmission electron microscope (TEM) was used to measure the number average primary particle diameter. For example, with respect to the resin fine particles contained in the suspension A-1, the number average primary particle diameter was 35 nm, and the glass transition point (Tg) was 74 ° C. The solid content concentration of each of the suspensions A-1 to A-11 was 2% by mass.

[Method of producing toner]
(Preparation of toner core)
20 mass parts of 1st binder resin (crystalline polyester resin synthesize | combined by the above-mentioned procedure) using FM mixer ("FM-20B" by Nippon Coke Kogyo Co., Ltd.), 2nd binder resin (the above-mentioned procedure 80 parts by mass of the non-crystalline polyester resin synthesized in 4), 6 parts by mass of carbon black ("MA 100" manufactured by Mitsubishi Chemical Co., Ltd.), release agent (ester wax: manufactured by NOF Corporation "Nissan Electol (registered trademark) ) WEP-9 ") 4 parts by mass were mixed.

Subsequently, using the twin screw extruder ("PCM-30" manufactured by Ikegai Co., Ltd.), the obtained mixture was fed at a material feed rate of 6 kg / hour, a shaft rotational speed of 160 rpm, and a setting temperature (cylinder temperature) of 120 ° C. Melt kneading. Thereafter, the obtained kneaded product was cooled. Subsequently, the cooled kneaded material was coarsely crushed using a grinder ("Rotoplex (registered trademark)" manufactured by Hosokawa Micron Corporation). Subsequently, the obtained coarsely pulverized material was pulverized using a pulverizer ("Turbo Mill RS type" manufactured by Freund Turbo Co., Ltd.). Subsequently, the obtained pulverized material was classified using a classifier ("Elbow Jet EJ-LABO type" manufactured by Nittetsu Mining Co., Ltd.). As a result, a toner core having a volume median diameter (D ₅₀ ) of 7 μm was obtained.

(Shell layer formation process)
A 1 L three-necked flask equipped with a thermometer and a stirring blade was set in a water bath, and 300 mL of deionized water was placed in the flask. Thereafter, the temperature in the flask was maintained at 30 ° C. using a water bath. Subsequently, dilute hydrochloric acid was added to the flask to adjust the pH of the contents of the flask to 4. Subsequently, in the flask, shell materials (suspensions specified for each toner, shown in Table 1) were added in amounts as shown in Table 1. For example, in the production of toner TA-1, 200 g of suspension A-1 was added as a shell material in a flask.

  Subsequently, 300 g of a toner core (toner core prepared by the above-mentioned procedure) was added to the flask. Subsequently, the temperature in the flask was raised to 70 ° C. at a rate of 1 ° C./min while stirring the flask contents at a rotational speed of 100 rpm. Subsequently, the contents of the flask were stirred for 2 hours at a temperature of 70 ° C. and a rotational speed of 100 rpm.

  Subsequently, sodium hydroxide was added to the flask to adjust the pH of the contents of the flask to 7. Subsequently, the contents of the flask were cooled until the temperature reached normal temperature (about 25 ° C.) to obtain a dispersion containing particles before treatment (toner base particles before mechanical treatment described later).

(Washing process)
The dispersion of pre-treated particles obtained as described above was filtered (solid-liquid separation) using a Buchner funnel to obtain wet cake-like pre-treated particles. Thereafter, the obtained wet cake-like pre-treated particles were re-dispersed in ion exchange water. Further, dispersion and filtration were repeated 5 times to wash the pre-treated particles.

(Drying process)
Subsequently, the obtained pre-treated particles were dispersed in a 50% by mass aqueous ethanol solution. This gave a slurry of pre-treated particles. Subsequently, the particles before treatment in the slurry are treated using a continuous surface reforming apparatus ("Cotemizer (registered trademark)" manufactured by Freund Sangyo Co., Ltd.) at a hot air temperature of 45 ° C and a blower air volume of 2 m ³ / min. It was allowed to dry.

(Mechanical processing)
Subsequently, using a fluid mixer ("FM-20C / I" manufactured by Japan Coke Industry Co., Ltd.), the particles before treatment are treated mechanically (more specifically, at a rotational speed of 3000 rpm and a jacket temperature of 20 ° C). Treatment for applying shear force was applied for 10 minutes. By applying mechanical treatment to the particles before treatment, powder of toner base particles was obtained.

(External addition process)
Subsequently, 100 parts by mass of toner mother particles and hydrophobic silica particles (Nippon Aerosil Co., Ltd.) are used at a rotational speed of 3000 rpm and a jacket temperature of 20 ° C. using an FM mixer (“FM-10B” manufactured by Japan Coke Industry Co., Ltd.) "AEROSIL (registered trademark) RA-200H" manufactured by the company, Content: Dry silica particles surface-modified with trimethylsilyl group and amino group, number average primary particle diameter: about 12 nm, 1.2 parts by mass, conductive titanium oxide Particles (“EC-100” manufactured by Titanium Kogyo Co., Ltd., base: TiO ₂ particles, coating layer: Sb-doped SnO ₂ film, number average primary particle diameter: about 0.35 μm) 0.8 parts by mass, for 2 minutes Mixed. Thereby, the external additive adhered to the surface of the toner base particles. Then, it sifted using the sieve of 200 mesh (75 micrometers of mesh openings). As a result, toners containing a large number of toner particles (toners TA-1 to TA-8 and TB-1 to TB-8 shown in Table 1) were obtained.

Regarding the toners TA-1 to TA-8 and TB-1 to TB-8 obtained as described above, the average adhesion F ₅₀ , the average transfer speed, and the Ru staining ratio were measured. The results are shown in Table 1. Met. For example, for toner TA-1, the average adhesion F ₅₀ was 21 nN, the average transfer rate was 6.2 mg / sec, and the Ru staining rate was 58%. The measurement method of each of the average adhesion F ₅₀ , the average transfer speed, and the Ru staining rate was as follows.

<Measurement method of average adhesion F ₅₀ >
As a measuring device, a centrifugal method adhesion measuring device ("NS-C200" manufactured by Nanoseeds, maximum rotational speed: 15,000 rpm, maximum acceleration: 16000 G) was used. The measuring device (NS-C 200) was provided with an image analysis unit (a photographing device, an image analysis device, and a video monitor) and a centrifugal separation unit (high speed centrifuge). For image analysis, image analysis software ("WinROOF" manufactured by Mitani Corporation) was used.

In the measurement of the average adhesive force F _50, an environment of RH temperature 22 ° C. and 50% humidity, (standard substrate of the measuring device: specular stainless steel plate) substrate was sprayed sample (toner) 0.05 g on. Specifically, the substrate was placed on a horizontal table, and a box (specifically, an open box with an open surface on the substrate side) was placed to cover the substrate. Holes were formed on the side of the box for introducing toner into the box. Subsequently, using compressed air, the toner was sprayed from the holes in the side of the box into the box to cause the toner to adhere to the surface of the substrate by free fall. As a result, a substrate for measurement (substrate to which toner was attached) was obtained.

  The surface on which the toner adheres is placed outside (opposite to the rotation center) at a position separated by a predetermined distance (rotation radius 6.6 cm) from the rotation center of the centrifugal rotor of the high-speed centrifuge. I set it to face. Subsequently, centrifugation was performed to rotate the centrifugal rotor. The rotational speed of the centrifugal rotor was gradually increased, and centrifugation was performed until the percentage of residual toner on the substrate was less than 50% by number. The higher the rotational speed of the centrifugal rotor, the smaller the toner retention rate on the substrate tends to be. The toner residual rate can be expressed by the equation “toner residual rate = 100 × the number of toners present on the substrate after centrifugation / the number of toners present on the substrate before centrifugation”.

During the centrifugal separation process, the image analysis unit of the measuring device records the separation state of the particles (more specifically, the toner residual rate etc.), and the particle density, the particle diameter, the rotational speed, and the rotational radius indicate the particles. Separation force (particle adhesion) was calculated automatically. Specifically, the average adhesion (average adhesion F ₅₀ ) at a toner remaining rate of 50% by number was calculated from the following equation.
Formula: F ₅₀ [nN] = (π / 6) ×) × d ³ × r × (2 × n ₅₀ × π / 60) ²
ρ: Toner density (unit: kg / m ³ )
d: Equivalent circle diameter of toner (unit: m)
r: Radius of rotation (unit: m)
n ₅₀ : Rotation speed at 50% of residual toner rate (unit: rpm)

<Method of measuring average transfer speed>
As a measurement apparatus, a vibration transfer type flowability measurement apparatus (manufactured by D IT Co., Ltd.) was used. This measuring device comprises a container (bowl) made of aluminum, a vibrating device (driving source) for vibrating the bowl, and a data recording device. The inner surface of the bowl is formed with a spiral slope from the center (bottom) of the bowl to the upper edge of the bowl. The center of the bowl corresponds to the sample injection position (start position of the slope). Further, at the top of the slope (the goal position on the slope) at the upper end edge of the bowl, a discharge port is provided. The measuring device further comprises a pan for receiving the sample discharged from the outlet and a balance for measuring the mass (transfer amount) of the sample contained in the pan. The vibrator vibrates the bowl to apply traveling wave vibrations to the sample introduced into the bowl. This vibration causes the sample to move circumferentially around the inner surface of the bowl along the slope (ie, climb up the spiral slope) to reach the top edge of the bowl (the top of the slope) and enter the receptacle It has become. The data recording device records, for example, the transition of the transfer amount (the amount of sample that has reached the receiving tray). From the data recorded by the data recording device, it is possible to grasp the relationship between the transfer amount and the vibration time (the time elapsed from the start of driving).

In the measurement of the average transfer speed, 1 g of a sample (toner) is placed in the center of the bowl under an environment of temperature 22 ° C. and humidity 50% RH, and the vibration device is driven under the conditions of frequency 120 Hz and voltage 100 V. , Vibrated the bowl. The time T ₁ from when the drive of the vibration device is started to the time when the transfer amount (the amount of toner reaching the saucer) reaches 300 mg, and the transfer amount (when the saucer reaches the charge since the drive of the vibration device starts and the time T ₂ of the until the amount of toner) becomes 600mg were respectively measured, the average transfer rate (units based on the following equation: mg / sec) was calculated.
Formula: Average feed rate _{= (600-300) / (T 2} -T 1)

<Method of measuring Ru staining rate>
Toner dispersion liquid is prepared by dispersing 2.0 g of a sample (toner) in 100 g of a 2% by mass aqueous solution of a nonionic surfactant ("Emulgen (registered trademark) 120" manufactured by Kao Corporation, component: polyoxyethylene lauryl ether) I got Subsequently, the obtained toner dispersion is subjected to ultrasonic treatment using an ultrasonic disperser ("Ultrasonic Mini Welder P128 manufactured by Ultrasonic Industry Co., Ltd., output: 100 W, oscillation frequency: 28 kHz), and a toner mother is obtained. The external additive was removed from the particles. Subsequently, the sonicated toner dispersion was suction filtered using qualitative filter paper ("FILTER PAPER No. 1" manufactured by Advantec Co., Ltd.). Thereafter, reslurry to which 50 mL of ion exchange water is added and suction filtration are repeated three times to obtain toner base particles of the sample (toner) (toner from which the external additive has been removed).

Subsequently, the obtained toner base particles (powder) are exposed in the atmosphere of normal temperature (25 ° C.) for 20 minutes in the vapor of 2 mL of a 5% by mass aqueous solution of RuO ₄ to obtain Ru of the toner base particles. Stained with (ruthenium). Then, the dyed toner base particles were photographed using a field emission scanning electron microscope (FE-SEM) ("JSM-7600F" manufactured by JEOL Ltd.) to obtain a reflection electron image of the toner base particles. . Of the surface area of the toner mother particles, the area stained with Ru (stained area) is displayed brighter than the area not stained with Ru (non-stained area). The imaging conditions of the FE-SEM were an acceleration voltage of 10.0 kV, an irradiation current of 95 pA, a magnification of 5000, a contrast of 4800, and a brightness of 550.

Subsequently, image analysis of the backscattered electron image was performed using an image analysis software ("WinROOF" manufactured by Mitani Corporation). Specifically, the backscattered electron image was converted into jpg format image data, and 3 × 3 Gaussian filter processing was performed. Subsequently, a luminance value histogram (vertical axis: frequency (number of pixels), horizontal axis: luminance value) of the filtered image data was obtained. The luminance value histogram showed the distribution of luminance values of the surface area (stained area and non-stained area) of the toner mother particle. With respect to the luminance value histogram, fitting to the normal distribution by the least squares method and waveform separation are performed, and a non-stained waveform indicating the distribution (normal distribution) of the luminance value of the non-stained region and the distribution (normal distribution) of the stained region And a staining waveform showing). Subsequently, the Ru staining rate (unit:%) was determined from the areas of the two obtained waveforms (the area R _C of the non-stained waveform and the area R _{S of the} stained waveform) based on the following equation.
Ru staining rate = 100 × _RS / ( _RC + _RS )

[Evaluation method]
The evaluation method of each sample (toner TA-1 to TA-8 and TB-1 to TB-8) is as follows.

(Heat resistant storage stability)
2 g of the sample (toner) was placed in a 20 mL polyethylene container, and the container was allowed to stand in a thermostat set at a temperature of 65 ° C. for 3 hours. Thereafter, the toner removed from the thermostat was cooled to room temperature to obtain a toner for evaluation (heat-treated toner).

Subsequently, the obtained evaluation toner was placed on a sieve of 100 mesh (opening 150 μm) of known weight. Then, the mass of the sieve containing the toner was measured, and the mass of the toner on the sieve (the mass of the toner before screening) was determined. Subsequently, the sieve was set on a powder tester (manufactured by Hosokawa Micron Corporation), and the sieve was vibrated for 30 seconds under the condition of the rheostat graduation 5 according to the manual of the powder tester to sift the evaluation toner. After sieving, the mass of the sieve containing the toner was measured to determine the mass of the toner remaining on the sieve (the mass of the toner after sieving). From the mass of the toner before screening and the mass of the toner after screening, the degree of aggregation (unit: mass%) was determined based on the following equation.
Cohesion degree = 100 × mass of toner after sieving / mass of toner before sieving

  When the degree of aggregation was 20% by mass or less, it was evaluated as ○ (good), and when the degree of aggregation exceeded 20% by mass, it was evaluated as × (not good).

(Preparation of two-component developer)
100 parts by mass of a developer carrier (carrier for "TASKalfa 5550ci" manufactured by KYOCERA Document Solutions Inc.) and 10 parts by mass of a sample (toner) were mixed using a ball mill for 30 minutes to prepare a two-component developer . Using the obtained two-component developer, the minimum fixing temperature, the transfer efficiency, and the cleaning property were evaluated by the following procedure.

(Minimum fixing temperature)
The two-component developer prepared as described above was used to form an image to evaluate the minimum fixing temperature. As an evaluation machine, a printer equipped with a roller-roller type heat and pressure fixing device (an evaluation machine capable of changing the fixing temperature by modifying “FS-C5250DN” manufactured by Kyocera Document Solutions Inc.) was used. The two-component developer prepared as described above was loaded into the developing device of the evaluation machine, and a sample (toner for replenishment) was loaded into the toner container of the evaluation machine.

A linear velocity of 200 mm / sec and a toner loading amount of 1.0 mg / cm on a paper having a basis weight of 90 g / m ² (A4 size printing paper) under an environment of temperature 25 ° C. and humidity 50% RH using the above evaluation machine ^Under the condition of ² , a solid image (specifically, an unfixed toner image) of 25 mm × 25 mm in size was formed. Subsequently, the paper on which the image was formed was passed through the fixing device of the evaluation machine.

  In the evaluation of the lowest fixing temperature, the setting range of the fixing temperature was 100 ° C. or more and 200 ° C. or less. Specifically, the fixing temperature of the fixing device is raised from 100 ° C. to 5 ° C. (however, 2 ° C. near the minimum fixing temperature) to obtain the minimum temperature (minimum fixing temperature) at which a solid image (toner image) can be fixed on paper. It was measured. Whether or not the toner could be fixed was confirmed by a rubbing test as shown below. More specifically, the evaluation sheet passed through the fixing device was folded so that the surface on which the image was formed was inside, and the image on the fold was rubbed back and forth five times using a 1 kg weight coated with a fabric. Subsequently, the paper was unfolded, and the folded part of the paper (the part where the solid image was formed) was observed. Then, the peeling length (peeling length) of the toner at the bent portion was measured. The lowest temperature of the fixing temperatures at which the peeling length is 1 mm or less was taken as the lowest fixing temperature. When the lowest fixing temperature was 150 ° C. or less, it was evaluated as ○ (good), and when the lowest fixing temperature exceeded 150 ° C., it was evaluated as × (not good).

(Transfer efficiency, cleanability)
For the evaluation of the transfer efficiency, a multifunction machine ("TASKalfa 5550ci" manufactured by KYOCERA Document Solutions, Inc.) was used as an evaluation machine. The two-component developer prepared as described above was set in the evaluation machine, and an image with a printing ratio of 5% was output at 10,000 sheets under the environment of a temperature of 32 ° C and a humidity of 80% RH while replenishing the sample (toner). . Then, the mass of the consumed toner and the mass of the recovered toner were respectively measured, and the transfer efficiency (unit:%) was calculated from the following equation. The consumed toner is the toner discharged from the toner container among the samples (toner) set in the toner container. Further, the recovered toner is a toner among the consumed toners that has not been transferred to the recording medium.
Transfer efficiency = 100 × (mass of consumed toner−mass of collected toner) / (mass of consumed toner)

  When the transfer efficiency was 90% or more, it was evaluated as ○ (good), and when the transfer efficiency was less than 90%, it was evaluated as x (not good).

  Furthermore, in order to evaluate the cleaning property, it was observed whether or not coloring with toner occurred on the surface of the photosensitive drum and whether a dash mark occurred on the formed solid image, based on the output of 10,000 sheets. When no coloring by toner was observed on the surface of the photosensitive drum and no dash mark was observed in the formed solid image, the cleaning property was evaluated as ○ (good). When it did not correspond to O, the cleaning property was evaluated as x (not good). The dash marks are image defects that may occur due to toner adhering to the surface of the photosensitive drum.

[Evaluation results]
The heat resistance storage stability (cohesion degree), low temperature fixability (minimum fixing temperature), transfer efficiency, and cleanability were evaluated for each of the toners TA-1 to TA-8 and TB-1 to TB-8. It is shown in 3.

The toners TA-1 to TA-8 (toners according to Examples 1 to 8) had the above-described basic configuration. Specifically, in toners TA-1 to TA-8, as shown in Tables 1 and 2, the shell layer is mainly composed of an assembly of heat-resistant particles (resin particles having a glass transition temperature of 50 ° C. or more and 100 ° C. or less). And the resin film comprised. As shown in Tables 1 and 2, the heat-resistant particles were substantially composed of a resin containing a repeating unit having an alcoholic hydroxyl group in a proportion of 0.5% by mass or more and 20% by mass or less. As shown in Table 1, the average adhesion F50 was ₅₀ n% or more and ₅₀ nN or less when the toner residual ratio was 50% by number, as measured by centrifugal adhesion. As shown in Table 1, the average transfer speed from 300 mg to 600 mg of transfer amount in the vibration transfer type flowability measurement under the condition of 1 g of toner input and 120 Hz of excitation frequency is 5.0 mg / sec or more. It was less than 10 mg / sec. As shown in Table 1, when the toner in the absence of the external additive is exposed for 20 minutes in the vapor of a 5% by mass RuO ₄ (ruthenium tetraoxide) aqueous solution, the toner base particles (the external additive is absent) Of the surface area of the toner particle in the state, an area of 50% or more and 70% or less was stained with Ru.

  As shown in Table 3, the toners TA-1 to TA-8 were each excellent in heat-resistant storage stability, low-temperature fixability, transferability, and cleanability.

  The electrostatic latent image developing toner according to the present invention can be used, for example, to form an image in a copying machine, a printer, or a multifunction machine.

10 toner mother particle 11 toner core 12 shell layer 12a resin particle 12b resin particle

Claims (4)

A toner for developing an electrostatic latent image, comprising a plurality of toner particles comprising a core containing a polyester resin and a shell layer covering the surface of the core,
The shell layer includes a resin film mainly composed of an assembly of resin particles having a glass transition temperature of 50 ° C. or more and 100 ° C. or less,
The resin particles are substantially constituted of a resin containing a repeating unit having an alcoholic hydroxyl group in a proportion of 0.5% by mass or more and 20% by mass or less,
The average adhesion at 50% by number of residual toner ratio by centrifugal adhesion measurement is 0.1 nN or more and 40 nN or less,
The average transfer speed from 300 mg to 600 mg in the vibration transfer type flowability measurement under the condition of 1 g of toner input and 120 Hz of vibration frequency is 5.0 mg / sec or more and 10 mg / sec or less,
50% to 70% of the surface area of the toner particles in the absence of an external additive when the toner in the absence of an external additive is exposed to the vapor of a 5% by mass aqueous solution of RuO ₄ for 20 minutes Area is stained with Ru ,
The resin constituting the resin particles is derived from one or more repeating units derived from a styrenic monomer, one or more repeating units derived from a (meth) acrylic acid alkyl ester, and a nitrogen-containing vinyl compound 1 Containing repeating units of a kind or more,
The toner for developing an electrostatic latent image, wherein a repeating unit having the highest mass ratio among repeating units contained in the resin constituting the resin particles is a repeating unit derived from a styrenic monomer . 2. The electrostatic latent image developing toner according to claim 1, wherein in the aggregate of the resin particles constituting the resin film, the resin particles are bonded to each other by a physical force. The core, as the polyester resin contains a crystalline polyester resin and amorphous polyester resin, the electrostatic latent image developing toner according to claim 1 or 2. The toner for developing an electrostatic latent image according to any one of claims 1 to 3 , wherein the toner particles further comprise inorganic particles as an external additive.