JP2019040024A - Toner and method for manufacturing the same - Google Patents

Abstract

To provide a toner that is excellent in both heat-resistant storage property and low-temperature fixability, and a method for manufacturing the same.SOLUTION: A toner includes a plurality of toner particles each including a toner core and a shell layer that covers the surface of the toner core. The toner core contains a fused and kneaded material of an amorphous resin and a crystalline resin. The shell layer contains a thermosetting resin. The fused and kneaded material includes a plurality of crystalline resin domains. Of the plurality of crystalline resin domains included in the toner particle, the ratio of domains satisfying the condition in which the minor axis diameter is 50 nm or more and 200 nm or less and the aspect ratio is 4.0 or more and 20.0 or less is 80 number% or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a toner and a manufacturing method thereof, and more particularly, to an electrostatic latent image developing toner and a manufacturing method thereof.

  Patent Document 1 discloses a toner containing a melt-kneaded product of an amorphous resin and a crystalline resin.

JP 2002-287426 A

  However, it is difficult to obtain a toner excellent in both heat-resistant storage stability and low-temperature fixability only by the technique disclosed in Patent Document 1. Specifically, although the low-temperature fixability of the toner can be improved by increasing the amount of the crystalline resin, it is difficult to ensure sufficient heat-resistant storage stability of the toner.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a toner excellent in both heat storage stability and low-temperature fixability and a method for producing the same.

  The toner according to the present invention includes a plurality of toner particles including a toner core and a shell layer covering the surface of the toner core. The toner core contains a melt-kneaded product of an amorphous resin and a crystalline resin. The shell layer contains a thermosetting resin. The melt-kneaded product includes a plurality of crystalline resin domains. Of the plurality of crystalline resin domains contained in the toner particles, the ratio of domains satisfying the conditions of the minor axis diameter of 50 nm to 200 nm and the aspect ratio of 4.0 to 20.0 is 80% by number or more. .

The toner production method according to the present invention includes a melt-kneading step, a pulverizing step, and a shell layer forming step. In the melt-kneading step, a toner material containing a crystalline resin and an amorphous resin is charged into a screw extruder, the screw rotation speed of the screw extruder is not less than 50 rpm and not more than 500 rpm, and the material inlet of the screw extruder The distance between the part and the material outlet part of the screw extruder is 30 cm or more and 300 cm or less, and the temperature of the material inlet part is “melting point of the crystalline resin + 20 ° C.” or more and “melting point of the crystalline resin + 40 ° C.” or less. And the temperature of the material outlet is not less than “temperature of the material inlet—60 ° C.” and not more than “temperature of the material inlet—40 ° C.”. Melt-kneaded to obtain a melt-kneaded product. In the pulverization step, the melt-kneaded product is pulverized to obtain a pulverized product including a plurality of particles. In the shell layer forming step, the pulverized product is put in a liquid, and a shell layer containing a thermosetting resin is formed on the surface of each of the plurality of particles included in the pulverized product in the liquid. The difference between the SP value of the non-crystalline resin and the SP value of the crystalline resin is 1.0 (cal / cm ³ ) ^1/2 or more and 1.4 (cal / cm ³ ) ^1/2 or less in absolute value. It is.

  According to the present invention, it is possible to provide a toner excellent in both heat-resistant storage stability and low-temperature fixability and a method for producing the same.

FIG. 4 is a diagram illustrating an example of a cross-sectional structure of toner particles contained in a toner according to an exemplary embodiment of the present invention. 4 is a photograph of a portion of the cross section of toner particles using a transmission electron microscope (TEM) for the toner according to the embodiment of the present invention. FIG. 2 is an enlarged view showing one crystalline resin domain in the toner particles shown in FIG. 1. FIG. 6 is a diagram for explaining a toner manufacturing method according to an embodiment of the present invention.

  An embodiment of the present invention will be described. Note that evaluation results (values indicating shape, physical properties, etc.) relating to powder (more specifically, toner base particles, external additives, toner, etc.) are included in the powder unless otherwise specified. It is the number average of the values measured for a considerable number of particles.

The number average particle diameter of the powder is the number average value of the equivalent circle diameter of primary particles (diameter of a circle having the same area as the projected area of the particles) measured using a microscope unless otherwise specified. . Moreover, the measured value of the volume median diameter (D ₅₀ ) of the powder is not specified, and the “Coulter Counter Multisizer 3” manufactured by Beckman Coulter Co., Ltd. is used. ) Measured based on.

  The measured value of the melting point (Mp) is an endothermic curve (vertical axis: heat flow (DSC signal)) measured using a differential scanning calorimeter (“DSC-6220” manufactured by Seiko Instruments Inc.) unless otherwise specified. , Horizontal axis: temperature) of the maximum endothermic peak. Moreover, each measured value of a number average molecular weight (Mn) and a mass average molecular weight (Mw) is the value measured using the gel permeation chromatography, if not prescribed | regulated at all.

  The “main component” of a material means a component most contained in the material on a mass basis unless otherwise specified.

  The chargeability means the chargeability in frictional charging unless otherwise specified. The strength of positive chargeability (or strength of negative chargeability) in frictional charging can be confirmed by a known charge train or the like.

Moreover, unless SP value (solubility parameter) prescribes | regulates at all, the calculation method of Fedors (RF Fedors, "Polymer Engineering and Science", 1974, Vol. 14, No. 2, p147-154) (Unit: (cal / cm ³ ) ^1/2 , temperature: 25 ° C.). The SP value is represented by the formula “SP value = (E / V) ^1/2 ” (E: molecular cohesive energy [cal / mol], V: molecular volume [cm ³ / mol]).

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

  The toner according to the exemplary embodiment can be suitably used for developing an electrostatic latent image, for example, as a positively chargeable toner. The toner of the present exemplary embodiment is a powder that includes a plurality of toner particles (each having a configuration described later). The toner may be used as a one-component developer. Alternatively, a two-component developer may be prepared by mixing toner and carrier using a mixing device (for example, a ball mill). An example of a carrier suitable for image formation is a ferrite carrier (specifically, a powder of ferrite particles). 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 ensure a sufficient charge imparting property of the carrier to the toner for a long period of time, the resin layer must completely cover the surface of the carrier core (that is, there is no surface area of the carrier core exposed from the resin layer). preferable. In order to impart magnetism to the carrier particles, the carrier core may be formed of a magnetic material (for example, a ferromagnetic substance such as ferrite), or the carrier core may be formed of a resin in which magnetic particles are dispersed. Good. Further, magnetic particles may be dispersed in the resin layer covering the carrier core. Examples of the resin constituting the resin layer are 1 selected from the group consisting of a fluororesin (more specifically, PFA or FEP), a polyamideimide resin, a silicone resin, a urethane resin, an epoxy resin, and a phenol resin. More than one type of resin may be mentioned. 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 number average primary particle diameter of the carrier is preferably 20 μm or more and 120 μm or less. The positively chargeable toner contained in the two-component developer is positively charged by friction with the carrier. The negatively chargeable toner contained in the two-component developer is negatively charged by friction with the carrier.

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

  First, an image forming unit (for example, a charging device and an exposure device) of an electrophotographic apparatus forms an electrostatic latent image on a photosensitive member (for example, a surface layer portion of a photosensitive drum) based on image data. Subsequently, a developing device of the electrophotographic apparatus (specifically, a developing device in which a developer containing toner is set) supplies the toner to the photoconductor to develop the electrostatic latent image formed on the photoconductor. The toner is charged by friction with the carrier, the developing sleeve, or the blade in the developing device before being supplied to the photoreceptor. For example, a positively chargeable toner is positively charged. In the developing process, toner (specifically, charged toner) on a developing sleeve (for example, a surface layer portion of a developing roller in the developing device) disposed in the vicinity of the photosensitive member is supplied to the photosensitive member, and the supplied toner is By attaching to the electrostatic latent image on the photoconductor, a toner image is formed on the photoconductor. The consumed toner is replenished to the developing device from a toner container containing replenishment toner.

  In the subsequent transfer process, after the transfer device of the electrophotographic apparatus transfers the toner image on the photosensitive member to an intermediate transfer member (for example, a transfer belt), the toner image on the intermediate transfer member is further transferred to a recording medium (for example, paper). Transcript to. Thereafter, a fixing device (fixing method: nip fixing with a heating roller and a pressure roller) of the electrophotographic apparatus heats and pressurizes the toner 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. After the transfer step, the toner remaining on the photoreceptor is removed by a cleaning member (for example, a cleaning blade). 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 using the intermediate transfer member. The fixing method may be a belt fixing method.

  The toner according to this embodiment includes a plurality of toner particles. The toner particles may include an external additive. When the toner particles include an external additive, the toner particles include a toner base particle and an external additive. The external additive adheres to the surface of the toner base particles. The toner base particles contain a binder resin. The toner base particles may contain an internal additive (for example, at least one of a release agent, a colorant, a charge control agent, and a magnetic powder) in addition to the binder resin, if necessary. If not necessary, the external additive may be omitted. When omitting the external additive, the toner base particles correspond to the toner particles.

  The toner according to the exemplary embodiment has the following configuration (hereinafter referred to as a basic configuration).

(Basic toner configuration)
The toner includes a plurality of toner particles including a toner core and a shell layer covering the surface of the toner core. The toner core contains a melt-kneaded product of an amorphous resin and a crystalline resin. The shell layer contains a thermosetting resin. The melt-kneaded product includes a plurality of crystalline resin domains. Of the plurality of crystalline resin domains contained in the toner particles, the ratio of domains satisfying the conditions of the minor axis diameter of 50 nm to 200 nm and the aspect ratio of 4.0 to 20.0 is 80% by number or more.

  Hereinafter, the crystalline resin domain contained in the toner particles may be referred to as “CR domain”. In addition, the CR domain number average minor axis diameter is “CR minor axis diameter”, the CR domain number average major axis diameter is “CR major axis diameter”, and the CR domain number average aspect ratio is “CR aspect ratio”. , May be described respectively. In addition, a CR domain that satisfies the conditions of a minor axis diameter of 50 nm to 200 nm and an aspect ratio of 4 to 20 may be referred to as a “CR compatible domain”. In addition, the ratio of the number of CR compatible domains among the CR domains contained in the toner particles may be simply referred to as “CR compatible domain ratio”.

  In the above basic configuration, the “aspect ratio” corresponds to a value obtained by dividing the major axis diameter by the minor axis diameter (= major axis diameter / minor axis diameter). The “major axis diameter” of a particle is the length of the major axis of the particle, and more specifically corresponds to the width of the particle that maximizes the interval between two parallel lines that sandwich the particle. The “minor axis diameter” of a particle is the length of the minor axis of the particle, and more specifically, the particle measured on a straight line passing through the midpoint of the major axis and orthogonal to the major axis. It corresponds to the width of.

  A technique for improving the low-temperature fixability of a toner by incorporating a melt-kneaded product of an amorphous resin and a crystalline resin into toner particles is generally known. In such a technique, a crystalline resin in a non-crystallized state is used, and the amorphous resin and the crystalline resin are compatible in the toner particles. By increasing the proportion of the crystalline resin in the compatible resin of the amorphous resin and the crystalline resin, the low-temperature fixability of the toner can be improved. However, if the ratio of the crystalline resin is increased too much, the heat resistant storage stability of the toner tends to be insufficient. The inventor of the present application assigns a majority of the crystalline resin domains (specifically, 80% to 100% by number) present in the toner particles to specific needle-like domains (specifically, the minor axis diameter is 50 nm to 200 nm and It was found that a toner excellent in both heat-resistant storage stability and low-temperature fixability can be obtained by using a crystalline resin domain satisfying an aspect ratio of 4 or more and 20 or less. Specifically, since the toner has the above-described basic configuration, it is possible to achieve both heat-resistant storage stability and low-temperature fixability of the toner.

  In the toner having the above-described basic configuration, the ratio of CR compatible domains is 80% by number or more. The CR compatible domain (that is, the acicular crystalline resin domain satisfying the condition that the minor axis diameter is 50 nm or more and 200 nm or less and the aspect ratio is 4 or more and 20 or less) has a higher sharp melt property than the spherical crystalline resin domain, When heated to the melting temperature, the time from when a part starts to melt until the whole is completely melted is short. Due to the presence of the CR compatible domain in the toner particles, the toner particles maintain a stable state (specifically, a relatively hard state) when the toner is stored, and when the toner is heated in the toner fixing process, the heating is performed. As a result, the toner particles are rapidly melted. On the other hand, in a toner in which crystalline resin domains having a shape close to a sphere are dispersed in toner particles, if the crystalline resin domain is large, the low-temperature fixability of the toner tends to be insufficient (the toner TB described later). -7), when the crystalline resin domain is small, the heat-resistant storage stability of the toner tends to be insufficient (see toner TB-1 described later). For this reason, it is difficult to achieve both heat-resistant storage stability and low-temperature fixability of the toner by using a crystalline resin domain having a shape close to a sphere. Further, in the toner having the above-described basic configuration, the aspect ratio of the CR compatible domain is not too large (specifically, 20.0 or less). When the aspect ratio of the crystalline resin domain dispersed in the toner particles is too large, the low-temperature fixability of the toner tends to be insufficient (see toner TB-5 described later). If the aspect ratio of the crystalline resin domains dispersed in the toner particles is too large, the crystalline resin domains come into contact with each other and a conductive path is easily formed. Such a conductive path serves as an escape route for electric charges and inhibits charging of the toner.

  In the toner having the above basic configuration, a CR compatible domain having an appropriate minor axis diameter (specifically, a minor axis diameter of 50 nm or more and 200 nm or less) exists in the toner particles. For this reason, it becomes easy to obtain a toner excellent in both heat-resistant storage stability and low-temperature fixability. If the short axis diameter of the crystalline resin domain dispersed in the toner particles is too small, the heat resistant storage stability of the toner tends to be insufficient (see toners TB-4 and TB-6 described later). If the short axis diameter of the crystalline resin domain dispersed in the toner particles is too large, the low-temperature fixability of the toner tends to be insufficient (see toner TB-3 described later).

  In the toner having the above-described basic configuration, the surface of the toner core is covered with the shell layer, thereby preventing the crystalline resin from being exposed on the surface of the toner core. The crystalline resin exposed on the surface of the toner core can cause charging failure of the toner. In addition, since the shell layer contains a thermosetting resin, the toner core is protected by the shell layer having excellent heat resistance when the toner is stored, and when the shell layer is destroyed in the toner fixing process, the toner core rapidly melts. The toner particles become soluble.

In order for the CR compatible domains to be present in the toner particles at a ratio of 80% by number or more, the difference between the SP value of the amorphous resin and the SP value of the crystalline resin is 1.0 (cal / cm) in absolute value. ³ ) It is preferable that it is ^1/2 or more and 1.4 (cal / cm ³ ) ^1/2 or less. With such a configuration, the non-crystalline resin and the crystalline resin in the toner particles can have appropriate compatibility.

  In the toner having the above-described basic configuration, the minor axis diameter of the plurality of crystalline resin domains is 50 nm or more and 200 nm or less in terms of the number average value, and the aspect ratio of the plurality of crystalline resin domains is 4.0 in terms of the number average value. It is preferable that it is 20.0 or less. When the CR minor axis diameter is 50 nm or more and 200 nm or less and the CR aspect ratio is 4.0 or more and 20.0 or less, it becomes easy to obtain a toner excellent in both heat storage stability and low-temperature fixability. Moreover, in order to put the CR minor axis diameter and the CR aspect ratio within the above-mentioned preferable ranges, the CR major axis diameter is preferably 250 nm or more and 2000 nm or less.

  In order to achieve both heat-resistant storage stability and low-temperature fixability of the toner, in the basic configuration described above, a plurality of crystalline resin domains should be dispersed in the toner particles with the major axis direction aligned. preferable. Multiple crystalline resin domains dispersed in toner particles are oriented in one direction, ensuring sufficient heat-resistant storage stability of toner even if the amount of crystalline resin domains in toner particles is small It becomes easy to do. In order to achieve both heat-resistant storage stability and low-temperature fixability of the toner, the amount of the crystalline resin in the toner particles is 3.0 parts by mass or more with respect to 100 parts by mass of the amorphous resin in the toner particles. The amount is preferably 5 parts by mass or less.

  Hereinafter, an example of toner particles contained in the toner having the above-described basic configuration will be described with reference to FIGS. FIG. 1 is a diagram showing a cross-sectional structure of toner particles 100 contained in a toner.

  A toner particle 100 shown in FIG. 1 includes toner base particles and an external additive (specifically, a plurality of external additive particles 22). The toner base particles include a toner core 10 and a shell layer 21. The shell layer 21 covers the surface of the toner core 10. The external additive is attached to the surface of the toner base particles. The toner core 10 includes an amorphous resin 11, a plurality of CR domains 12 (for example, crystalline polyester resin domains) dispersed in the amorphous resin 11 and a plurality of release agent domains 13 (for example, waxes, respectively). Domain). The plurality of CR domains 12 and the plurality of release agent domains 13 are each dispersed in the toner core 10. The external additive particles 22 are, for example, silica particles.

  FIG. 2 is a photograph of a cross section of toner particles contained in the toner having the above-described basic configuration, taken at a magnification of 30000 using a transmission electron microscope (TEM). In FIG. 2, the black region shows the crystalline resin domain (that is, CR domain 12) in a crystallized state. As shown in FIG. 2, the plurality of CR domains 12 are dispersed in the amorphous resin 11 with the major axis direction aligned.

FIG. 3 shows an enlarged view of one CR domain 12. In CR domain 12 shown in FIG. 3, D _A corresponds to the major axis diameter, D _B corresponds to the minor axis diameter, "D _A / D _B" corresponds to the aspect ratio.

  By crystallizing the crystalline resin in the toner particles, the amorphous resin and the crystalline resin can be phase-separated in the toner particles to form a crystalline resin domain in the toner particles. However, it is difficult to uniformly crystallize the crystalline resin in the toner particles so that the CR compatible domain exists in the toner particles at a ratio of 80% by number or more. The inventor of the present application has repeated experiments and studies and solved these problems by the following method. Hereinafter, a toner manufacturing method having the following configuration may be referred to as a “toner manufacturing method according to the exemplary embodiment”.

(Configuration of Toner Manufacturing Method According to this Embodiment)
The toner production method includes a melt-kneading step, a pulverizing step, and a shell layer forming step. In the melt-kneading step, a toner material containing a crystalline resin and an amorphous resin is charged into a screw extruder, the screw rotation speed of the screw extruder is 50 rpm or more and 500 rpm or less, and the material inlet portion of the screw extruder and the screw The distance from the material outlet of the extruder is 30 cm or more and 300 cm or less, the temperature of the material inlet is “the melting point of the crystalline resin + 20 ° C.” or more and “the melting point of the crystalline resin + 40 ° C.” or less, and the material outlet The toner material is melt-kneaded by a screw extruder under the condition that the temperature of the part is “the temperature of the material inlet part−60 ° C.” or more and “the temperature of the material inlet part−40 ° C.” to obtain a melt-kneaded product. The difference between the SP value of the amorphous resin and the SP value of the crystalline resin is 1.0 (cal / cm ³ ) ^1/2 or more and 1.4 (cal / cm ³ ) ^1/2 or less. In the pulverization step, the melt-kneaded product is pulverized to obtain a pulverized product including a plurality of particles. In the shell layer forming step, the pulverized material obtained in the pulverizing step is put in a liquid, and a shell layer containing a thermosetting resin is formed on the surface of each of the plurality of particles included in the pulverized material in the liquid. .

  In the toner manufacturing method according to this embodiment, as the screw extruder, for example, a twin screw extruder 30 as shown in FIG. 4 can be used. The twin-screw extruder 30 includes a hopper 31, a cylinder 32, a screw 33, and a plurality of heaters 34. The hopper 31 includes a feeder (quantitative supply device) (not shown), and is configured to supply material into the cylinder 32 at a predetermined speed. The cylinder 32 has a cylindrical shape and is constituted by a plurality of cylindrical blocks connected in the axial direction. In the cylinder 32, two screws 33 (only one is shown) are arranged. The base ends of the two screws 33 are connected to a motor (not shown). Each of the two screws 33 is driven by a motor. Each of the plurality of heaters 34 is provided on the outer peripheral surface of the cylinder 32. Specifically, a heater 34 is provided for each cylindrical block constituting the cylinder 32. Each of the plurality of heaters 34 is configured to heat the cylinder 32 in response to a command (specifically, an electric signal) from a control unit (not shown) (for example, a processor such as a CPU). The temperature of the cylinder 32 can be adjusted by controlling the heater 34 by the control unit. By providing the heater 34 for each cylindrical block constituting the cylinder 32, the temperature of each of the cylindrical blocks can be adjusted separately. Each part of the cylinder 32 can be set to a predetermined temperature by the plurality of heaters 34. Further, the material in the cylinder 32 can be kneaded by the screw 33. Specifically, the material in the cylinder 32 is kneaded by the rotation of the two screws 33. In the twin-screw extruder 30, the connecting portion between the hopper 31 and the cylinder 32 corresponds to the material inlet portion P1, and the tip portion of the screw 33 corresponds to the material outlet portion P2. A temperature sensor S1 is provided at the material inlet P1 of the twin screw extruder 30, and a temperature sensor S2 is provided at the material outlet P2 of the twin screw extruder 30, respectively. The distance D between the material inlet portion P1 and the material outlet portion P2 is not less than 30 cm and not more than 300 cm.

  In the twin-screw extruder 30 shown in FIG. 4, temperature sensors S1 and S2 are provided in order to directly control the temperatures of the material inlet P1 and the material outlet P2. However, these temperature sensors S1 and S2 can be omitted. For example, when the temperature of the material inlet P1 and the temperature of the heater 34 disposed in the vicinity of the material inlet P1 (specifically, the temperature controlled by the controller) have a certain relationship, the temperature sensor S1. Even if there is no, the temperature of the material inlet P1 can be controlled based on the temperature of the heater 34 (that is, the drive signal from the controller to the heater 34). The same applies to the temperature sensor S2.

In the toner manufacturing method according to the present embodiment, a crystalline resin and an amorphous resin having SP values that are moderately separated are used. Specifically, the difference between the SP value of the amorphous resin and the SP value of the crystalline resin is 1.0 (cal / cm ³ ) ^1/2 or more and 1.4 (cal / cm ³ ) ^{1/2 in} absolute value. It is as follows. The toner material containing these crystalline resin and non-crystalline resin has a material inlet portion temperature of “the melting point of the crystalline resin + 20 ° C.” or more and “the melting point of the crystalline resin + 40 ° C.” or less, and the temperature of the material outlet portion However, it is melt-kneaded under the condition that the temperature of the material inlet is -60 ° C. or higher and the temperature of the material inlet is -40 ° C. or lower. In such a method, the temperature of the material inlet is appropriately higher than the melting point of the crystalline resin, so that the crystalline resin can be appropriately dispersed in the toner material. Further, since the temperature of the material outlet portion is sufficiently lower than the temperature of the material inlet portion and not too low, an appropriate temperature gradient is formed from the material inlet portion to the material outlet portion. Due to such temperature gradient, the crystalline resin in the melt-kneaded product gradually crystallizes as the melt-kneading proceeds, and a plurality of needle-like domains (specifically, crystalline resin domains) are formed in the melt-kneaded product. According to the temperature gradient, the plurality of needle-like domains in the melt-kneaded product are oriented in the axial direction of the cylinder of the screw extruder (that is, the axial direction of the screw). By setting the temperature of the material inlet and the temperature of the material outlet to the above temperature ranges, the crystalline resin in the melt-kneaded product is crystallized in a uniform manner, A crystalline resin domain having a form (specifically, a domain satisfying a condition of a minor axis diameter of 50 nm to 200 nm and an aspect ratio of 4.0 to 20.0, respectively) is formed. By pulverizing such a melt-kneaded product containing crystalline resin domains, CR compatible domains can be present in the toner particles at a ratio of 80% by number or more. The difference between the SP value of the amorphous resin and the SP value of the crystalline resin is 1.0 (cal / cm ³ ) ^1/2 or more and 1.4 (cal / cm ³ ) ^1/2 or less in absolute value. Thus, the size of the crystalline resin domain can be controlled based on the kneading conditions. If the difference between the SP value of the amorphous resin and the SP value of the crystalline resin is too large, the SP value of the crystalline resin is naturally incompatible and the crystalline resin domain tends to be too large. On the other hand, if the difference between the SP value of the amorphous resin and the SP value of the crystalline resin is too small, the amorphous resin and the crystalline resin may become incompatible even if the kneading conditions are changed. Inability to do so tends to make the crystalline resin domain too small.

  In the toner manufacturing method according to this embodiment, the screw rotation speed of the screw extruder is 50 rpm or more and 300 rpm or less, and the distance between the material inlet portion of the screw extruder and the material outlet portion of the screw extruder is 30 cm or more and 100 cm or less. It is particularly preferred that In order to improve the uniformity of the crystalline resin domains in the toner particles, the toner material includes a crystalline resin having a number average molecular weight (Mn) of 3000 to 4500 and a number average molecular weight (Mn) of 1000 to 1500. It is particularly preferable to use an amorphous resin.

  In order to suppress the dissolution or elution of the toner components (particularly, the resin and the release agent) in the shell layer forming step, the toner core (specifically, the pulverized product of the melt-kneaded product) is dispersed in the aqueous medium, and the aqueous medium Among them, it is preferable to form a shell layer on the surface of the toner core. The aqueous medium is a medium containing water as a main component (more specifically, pure water or a mixed liquid of water and a polar medium). The aqueous medium functions as a solvent, and the solute may be dissolved in the aqueous medium. The aqueous medium functions as a dispersion medium, and the dispersoid may be dispersed in the aqueous medium. As a polar medium in the aqueous medium, for example, alcohol (more specifically, methanol or ethanol) can be used. The boiling point of the aqueous medium is about 100 ° C.

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

  Hereinafter, a suitable example of the configuration of the toner particles will be described. The toner base particles and the external additive will be described in order. Depending on the use of the toner, unnecessary components may be omitted.

[Toner mother particles]
In the toner having the basic configuration described above, the toner base particles include a toner core and a shell layer that covers the surface of the toner core.

(Toner core: non-crystalline resin, crystalline resin)
In the toner having the basic configuration described above, the toner core contains a melt-kneaded product of an amorphous resin and a crystalline resin. The amorphous resin functions as a binder resin. The main component of the toner core is preferably an amorphous resin. As the non-crystalline resin, non-crystalline polyester resin is preferable, number average molecular weight (Mn) 1000 to 2000, mass average molecular weight (Mw) 15000 to 20000, acid value 10.0 mgKOH / g to 25.0 mgKOH / g. Hereinafter, an amorphous polyester resin having an SP value of 8.5 (cal / cm ³ ) ^{1/2 to} 12.0 (cal / cm ³ ) ^1/2 and Tg (glass transition point) of 35 ° C. to 50 ° C. Particularly preferred. As the crystalline resin, a crystalline polyester resin is preferable, a number average molecular weight (Mn) of 3000 to 4500, a mass average molecular weight (Mw) of 15000 to 20000, an acid value of 10.0 mgKOH / g to 25.0 mgKOH / g, A crystalline polyester resin having an SP value of 8.5 (cal / cm ³ ) ^{1/2 to} 12.0 (cal / cm ³ ) ^1/2 and Mp (melting point) of 75 ° C. to 90 ° C. is particularly preferable. Preferable examples of the amorphous polyester resin include 1,2-propanediol as the alcohol component, and aromatic dicarboxylic acid (for example, terephthalic acid) and / or unsaturated dicarboxylic acid (for example, fumaric acid) as the acid component. Non-crystalline polyester resin containing acid). Preferred examples of the crystalline polyester resin include an α, ω-alkanediol having 2 to 12 carbon atoms (for example, 1,6-hexanediol having 6 carbon atoms) as the alcohol component, and carbon as the acid component. Examples thereof include crystalline polyester resins containing an α, ω-alkanedicarboxylic acid having a number of 8 or more and 18 or less (for example, 1,10-decanedicarboxylic acid having 12 carbon atoms).

  The polyester resin is composed of one or more polyhydric alcohols (more specifically, aliphatic diol, bisphenol, trihydric or higher alcohol as shown below) and one or more polyhydric carboxylic acids (more specifically). Specifically, it can be obtained by polycondensation with a divalent carboxylic acid or a trivalent or higher carboxylic acid as shown below. The polyester resin may contain a repeating unit derived from another monomer (a monomer that is neither a polyhydric alcohol nor a polyvalent carboxylic acid).

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

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

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

  Preferable examples of the divalent carboxylic acid include aromatic dicarboxylic acid (more specifically, phthalic acid, terephthalic acid, or isophthalic acid), α, ω-alkanedicarboxylic acid (more specifically, malonic acid). Succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, or 1,10-decanedicarboxylic acid), unsaturated dicarboxylic acid (more specifically, maleic acid, fumaric acid, citraconic acid, itaconic acid, Or glutaconic acid or the like), or cycloalkane dicarboxylic acid (more specifically, cyclohexane dicarboxylic acid or the like).

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

(Toner core: Colorant)
The toner core may contain a colorant. As the colorant, a known pigment or dye can be used according to the color of the toner. In order to obtain a toner suitable for image formation, 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. An example of a black colorant is carbon black. The black colorant may be a colorant that is toned to black using a yellow colorant, a magenta colorant, and a cyan colorant.

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

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

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

(Toner core: 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 offset resistance of the toner. In order to improve the fixing property or offset resistance of the toner, the amount of the release 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.

  Examples of the release agent include 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 a block thereof Oxides of aliphatic hydrocarbon waxes such as copolymers; plant waxes such as candelilla wax, carnauba wax, wood wax, jojoba wax, or rice wax; animal properties such as beeswax, lanolin, or whale wax Waxes; mineral waxes such as ozokerite, ceresin, or petrolatum; waxes based on fatty acid esters such as montanate ester wax or castor wax; fats such as deoxidized 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 multiple types of release agents may be used in combination.

(Toner core: 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 rising property of the toner. The charge rising characteristic of the toner is an index as to whether or not the toner can be charged to a predetermined charge level in a short time.

  By adding a negatively chargeable charge control agent (more specifically, an organometallic complex or a chelate compound) to the toner core, the anionicity of the toner core can be enhanced. Further, by adding a positively chargeable charge control agent (more specifically, pyridine, nigrosine, quaternary ammonium salt, or the like) to the toner core, the toner core can be made more cationic. However, when sufficient chargeability is ensured in the toner, it is not necessary to include a charge control agent in the toner core.

(Toner core: magnetic powder)
The toner core may contain magnetic powder. Examples of magnetic powder materials include ferromagnetic metals (more specifically, iron, cobalt, nickel, or alloys containing one or more of these metals), ferromagnetic metal oxides (more specifically, Ferrite, magnetite, chromium dioxide, or the like) or a material subjected to ferromagnetization treatment (more specifically, a carbon material or the like imparted with ferromagnetism by heat treatment) can be suitably used. One type of magnetic powder may be used alone, or a plurality of types of magnetic powder may be used in combination.

  In addition, in order to suppress elution of metal ions (for example, iron ions) from magnetic powder, magnetic powder (more specifically, with a surface treatment agent (more specifically, silane coupling agent or titanate coupling agent)) The surface of each magnetic particle contained in the magnetic powder is preferably treated.

(Shell layer)
In the toner having the basic structure described above, the shell layer contains a thermosetting resin. As the thermosetting resin, an aminoaldehyde resin, a polyimide resin (more specifically, a maleimide polymer or a bismaleimide polymer), or a xylene resin is preferable, and an aminoaldehyde resin is particularly preferable. By covering the surface of the toner core with a shell layer containing an aminoaldehyde resin, it becomes easy to obtain a toner excellent in all of heat-resistant storage stability, low-temperature fixability, and positive chargeability. An aminoaldehyde resin is a resin produced by condensation polymerization of a compound having an amino group and an aldehyde (for example, formaldehyde). Examples of aminoaldehyde resins include melamine resins, urea resins, sulfonamide resins, glyoxal resins, guanamine resins, or aniline resins.

  In order to achieve both heat-resistant storage stability and low-temperature fixability of the toner, the shell layer preferably covers an area of 80% to 100% of the surface area of the toner core. Hereinafter, the area ratio of the surface area of the toner core covered by the shell layer may be referred to as “shell coverage”. A shell coverage of 100% means that the entire surface of the toner core is covered with the shell layer. The shell coverage can be measured, for example, by analyzing an image of toner particles (for example, pre-stained toner particles) taken with a field emission scanning electron microscope (“JSM-7600F” manufactured by JEOL Ltd.). . The covered area and the other area (non-covered area) on the surface of the toner core can be distinguished by, for example, a difference in luminance value.

  In order to achieve both heat-resistant storage stability and low-temperature fixability of the toner, the thickness of the shell layer is preferably 1 nm or more and 100 nm or less. The thickness of the shell layer can be measured by analyzing a TEM (transmission electron microscope) image of the cross section of the toner particles using commercially available image analysis software (for example, “WinROOF” manufactured by Mitani Corporation). If the thickness of the shell layer is not uniform in one toner particle, four equally spaced locations (specifically, two straight lines that are perpendicular to each other at the approximate center of the cross section of the toner particle are drawn. The thickness of the shell layer is measured at each of the four points where the straight line intersects the shell layer, and the arithmetic average of the four measured values obtained is taken as the evaluation value of the toner particles (shell layer thickness). The boundary between the toner core and the shell layer can be confirmed, for example, by selectively dyeing only the shell layer of the toner core and the shell layer. When the boundary between the toner core and the shell layer is unclear in the TEM photographed image, a characteristic element contained in the shell layer in the TEM photographed image is formed by combining TEM and electron energy loss spectroscopy (EELS). By performing the mapping, the boundary between the toner core and the shell layer can be clarified.

[External additive]
An external additive (specifically, a powder containing a plurality of external additive particles) may be adhered to the surface of the toner base particles. Unlike the internal additive, the external additive does not exist inside the toner base particles, but selectively exists only on the surface of the toner base particles (surface layer portion of the toner particles). For example, by stirring together the toner base particles (powder) and the external additive (powder), the external additive particles can be attached to the surface of the toner base particles. The toner base particles and the external additive particles do not chemically react with each other and are physically bonded instead of chemically. The strength of the bond between the toner base particles and the external additive particles depends on the stirring conditions (more specifically, the stirring time, the rotation speed of the stirring, etc.), the particle diameter of the external additive particles, and the shape of the external additive particles. And the surface condition of the external additive particles.

  In order to fully perform the functions of the external additive while suppressing the detachment of the external additive particles from the toner particles, the amount of the external additive (if multiple types of external additive particles are used, The total amount of external additive particles) 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.

  The external additive particles are preferably inorganic particles such as silica particles or metal oxide particles (more specifically, alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, or barium titanate). Particularly preferred. However, particles of an organic acid compound such as a fatty acid metal salt (more specifically, zinc stearate) or resin particles may be used as the external additive particles. Moreover, you may use the composite particle which is a composite of a multiple types of material as external additive particle | grains. One type of external additive particles may be used alone, or a plurality of types of external additive particles may be used in combination.

  In order to improve the fluidity of the toner, it is preferable to use inorganic particles (powder) having a number average primary particle diameter of 5 nm to 30 nm as external additive particles. In order to make the external additive function as a spacer between the toner particles to improve the heat-resistant storage stability of the toner, resin particles (powder) having a number average primary particle diameter of 50 nm to 200 nm are used as the external additive particles. It is preferable to do.

  Examples of the present invention will be described. Table 1 shows toners TA-1 to TA-6 and TB-1 to TB-7 (electrostatic latent image developing toners) according to Examples or Comparative Examples.

  In Table 1, “CPES” means crystalline polyester resin. Regarding the types of CPES in Table 1, “1” to “4” mean crystalline polyester resins CPES-1 to CPES-4 shown in Table 2, respectively. Further, in the production of each of the toners TA-1 to TA-6 and TB-1 to TB-7 shown in Table 1, in addition to the crystalline polyester resin (CPES) shown in Table 2, the non-crystalline property shown in Table 3 is used. Polyester resin APES was also used.

  Regarding the kneading conditions in Table 1, “inlet temperature” means the temperature at the material inlet of a screw extruder (specifically, a twin screw extruder) used for melt kneading, and “outlet temperature” means the temperature for melt kneading. It means the temperature at the material outlet of the screw extruder used (specifically, a twin screw extruder).

Regarding the shell materials in Table 1, “S-1” and “S-2” mean the shell materials S-1 and S-2 shown below, respectively.
The shell material S-1 was an aqueous solution of hexamethylolmelamine initial polymer (“Milben (registered trademark) Resin SM-607” manufactured by Showa Denko KK, solid content concentration: 80 mass%).
The shell material S-2 was an aqueous solution of methylated urea (“Nikalac (registered trademark) MX-280” manufactured by Sanwa Chemical Co., Ltd., solid content concentration: 95 mass%).

  Hereinafter, the production methods, evaluation methods, and evaluation results of the toners TA-1 to TA-6 and TB-1 to TB-7 will be described in order. In the evaluation in which an error occurs, a considerable number of measurement values with sufficiently small errors are obtained, and the arithmetic average of the obtained measurement values is used as the evaluation value. Further, Tg (glass transition point), Mp (melting point), number average molecular weight (Mn), mass average molecular weight (Mw), and acid value are measured as follows unless otherwise specified. .

<Measurement method of Tg and Mp>
As a measuring device, a differential scanning calorimeter (“DSC-6220” manufactured by Seiko Instruments Inc.) was used. By measuring the endothermic curve of the sample using a measuring apparatus, the Tg (glass transition point) and Mp (melting point) of the sample were determined. Specifically, 10 mg of a sample (for example, resin) was placed in an aluminum dish (aluminum container), and the aluminum dish was set in the measurement unit of the measuring device. In addition, an empty aluminum dish was used as a reference. In measurement of the endothermic curve, the temperature of the measurement part was increased from the measurement start temperature of 25 ° C. to 200 ° C. at a rate of 10 ° C./min. During the temperature increase, the endothermic curve (vertical axis: heat flow (DSC signal), horizontal axis: temperature) of the sample was measured. The Tg and Mp of the sample were read from the obtained endothermic curve. In the endothermic curve, the temperature of the inflection point due to the glass transition (specifically, the intersection of the extrapolation line of the baseline and the extrapolation line of the falling line) corresponds to the Tg (glass transition point) of the sample, and melting. The temperature of the endothermic peak due to heat (that is, the temperature at which the endothermic amount becomes maximum) corresponds to the Mp (melting point) of the sample.

<Measuring method of Mn and Mw>
The number average molecular weight (Mn) and mass average molecular weight (Mw) of a sample (for example, resin) were measured by gel permeation chromatography (GPC). Tetrahydrofuran (THF) was used as the solvent. A sample (for example, resin) was added to THF so that a solution having a concentration of 3.0 mg / mL was obtained, and the sample was allowed to stand for 1 hour to dissolve the sample in THF. The obtained THF solution was filtered using a non-aqueous sample pretreatment filter (“Chromatodisc 25N” manufactured by Kurashiki Boseki Co., Ltd., membrane pore size: 0.45 μm) to obtain a sample solution for measurement. The GPC measurement conditions were as follows.

(GPC measurement conditions)
Measuring device: “HLC-8220GPC” manufactured by Tosoh Corporation
Eluent: THF (tetrahydrofuran)
Column: Column for organic solvent SEC (size exclusion chromatography) (“TSKgel GMHXL” manufactured by Tosoh Corporation, packing material: styrenic polymer, column size: inner diameter 7.8 mm × length 30 cm, packing particle diameter: 9 μm)
Number of columns: 2 Detector: RI (refractive index) detector Eluent flow rate: 1 mL / min Sample solution concentration: 3.0 mg / mL
Column temperature: 40 ° C
Sample solution volume: 100 μL
Calibration curve: Standard monodisperse polystyrene sample manufactured by Tosoh Corporation (polystyrene molecular weight: 3.84 × 10 ⁶ , 1.09 × 10 ⁶ , 3.55 × 10 ⁵ , 1.02 × 10 ⁵ , 4.39 × 10 ⁴ , 9.10 × 10 ³ , and 2.98 × 10 ³ )

  A column was set in the heat chamber of the measuring device. The column was stabilized in the heat chamber at a temperature of 40 ° C. while controlling the temperature of the heat chamber at 40 ° C. Subsequently, a solvent (THF) was passed through the column at a temperature of 40 ° C. at a flow rate of 1 mL / min, and 100 μL of the sample solution was introduced into the column. The elution curve (vertical axis: detection intensity (count number), horizontal axis: elution time) was measured for the sample solution introduced into the column. Based on the obtained elution curve and the above calibration curve (specifically, a graph showing the relationship between the logarithmic value of molecular weight and elution time for each standard substance with known molecular weight), the GPC molecular weight distribution of the sample was determined. And the number average molecular weight (Mn) and the mass average molecular weight (Mw) of the sample were obtained from the obtained GPC molecular weight distribution.

<Method for measuring acid value>
The acid value of the sample (for example, resin) was measured according to JIS (Japanese Industrial Standard) K2501-2003. The acid value corresponds to the number of milligrams (mg) of potassium hydroxide required to neutralize the acidic component contained in 1 g of the sample.

  Xylene and dimethylformamide were mixed at a mass ratio of 1: 1. Subsequently, a sample (for example, resin) was dissolved in the obtained mixed solution to obtain a sample solution for measurement. And the acid value of the sample was calculated | required by the potentiometric titration method using the potassium hydroxide ethanol solution with a density | concentration of 0.1 mol / L as a titrant. Specifically, a titrant (potassium hydroxide / ethanol solution) was dropped into the sample solution obtained as described above, and potassium hydroxide added until the inflection point (that is, titration end point) appeared on the titration curve. From the amount, the acid value of the sample was determined.

[Preparation of materials]
(External additive: Preparation of silica particles)
Using a supersonic jet pulverizer (“Jet Mill IDS-2” manufactured by Nippon Pneumatic Industry Co., Ltd.), hydrophilic fumed silica particles (“AEROSIL (registered trademark) 200” manufactured by Nippon Aerosil Co., Ltd.), surface treatment: None , Number average primary particle size: about 12 nm). The crushed silica particles (powder) are put in a closed FM mixer (manufactured by Nippon Coke Kogyo Co., Ltd.) and sprayed toward 100 parts by mass of silica particles with a hydrophobizing agent (3-aminopropyltriethoxysilane and 20 parts by mass of a solution containing dimethyl silicone oil in a mass ratio of 1: 1 was sprayed uniformly. Subsequently, the surface of the silica particles was hydrophobized by reacting at 110 ° C. for 2 hours while mixing the silica particles and the hydrophobizing agent using a closed FM mixer. Subsequently, after the side reaction product was removed by a reduced pressure treatment, a heat treatment at 200 ° C. was further performed for 1 hour to obtain hydrophobic silica particles (powder).

(External additive: Preparation of titanium oxide particles)
A mixture of titanium tetrachloride and oxygen gas produced by the chlorine method was introduced into the gas phase oxidation reactor. Subsequently, titanium oxide (bulk) was obtained by performing a gas phase oxidation reaction of the mixture at a temperature of 1000 ° C. in the reactor. The obtained titanium oxide (bulk) was pulverized using a hammer mill. Subsequently, the obtained pulverized titanium oxide was washed and then dried at a temperature of 110 ° C. Furthermore, the dried pulverized titanium oxide was pulverized using a jet mill. As a result, fine titanium oxide particles (titanium oxide by a vapor phase method) were obtained.

Subsequently, using an FM mixer (manufactured by Nippon Coke Kogyo Co., Ltd.), 100 parts by mass of the obtained titanium oxide fine particles and 2.6 parts by mass of isopropyl triisostearoyl titanate are subjected to a coupling reaction at a temperature of 130 ° C. Thus, the titanium oxide fine particles were surface-treated. Subsequently, the surface-treated titanium oxide fine particles were dried and then crushed. As a result, fine titanium oxide particles having an electrical resistivity of 1.0 × 10 ⁹ Ω · cm and a methanol hydrophobization degree of 35% were obtained. Since the electrical resistivity of the titanium oxide fine particles is likely to vary depending on the manufacturing conditions, the titanium oxide fine particles were repeatedly produced until titanium oxide fine particles having a desired electrical resistivity were obtained.

Subsequently, the obtained titanium oxide fine particles were subjected to tin antimony treatment. Specifically, the obtained titanium oxide fine particles were dispersed in water to prepare a 100 g / L suspension of titanium oxide fine particles. Subsequently, the obtained titanium oxide suspension was heated to 70 ° C. Furthermore, a solution prepared by dissolving 2 g of tin chloride (SnCl ₄ .5H ₂ O) and 0.1 g of antimony chloride (SbCl ₂ ) in 50 mL of 2N hydrochloric acid aqueous solution and a 10% by mass sodium hydroxide aqueous solution were oxidized. It was added over 1 hour to the titanium oxide suspension so that the pH of the titanium suspension was maintained at 2-3. As a result, a conductive layer composed of each hydrate of tin oxide and antimony oxide was formed on the surface of the titanium oxide fine particles in the titanium oxide suspension.

  Thereafter, the titanium oxide suspension was filtered (solid-liquid separation), and the resulting titanium oxide fine particles were washed. Subsequently, the washed titanium oxide fine particles were fired at a temperature of 600 ° C. Subsequently, the fired titanium oxide fine particles were crushed using a jet mill (manufactured by Nippon Pneumatic Industry Co., Ltd.). As a result, conductive titanium oxide particles (powder) having an electrical resistivity of 50 Ω · cm and a hydrophilic property were obtained.

[Toner Production Method]
(Production of toner core)
Using an FM mixer ("FM-20B" manufactured by Nippon Coke Kogyo Co., Ltd.), 80 parts by mass of the crystalline resin (any of crystalline polyester resins CPES-1 to CPES-4) shown in Table 1, and Table 3 7 parts by mass of an amorphous resin (non-crystalline polyester resin APES) having the physical properties shown, 5 parts by mass of carbon black (“REGAL (registered trademark) 330R” manufactured by Cabot), and carnauba wax (manufactured by Hiroyuki Kato “ Carnauba wax No. 1 ") 5 parts by mass and polymer type positively chargeable charge control agent (" Acrybase (registered trademark) FCA-201-PS "manufactured by Fujikura Kasei Co., Ltd.), component: repeated from quaternary ammonium salt 3 parts by mass of styrene-acrylic acid resin containing units) was mixed. For example, in the production of the toner TA-1, a crystalline polyester resin CPES-1 is used as the crystalline resin. In the production of the toner TA-6, a crystalline polyester resin CPES-2 was used as the crystalline resin. Each of the crystalline polyester resins CPES-1 to CPES-4 had the physical properties shown in Table 2.

  Subsequently, the obtained mixture was mixed using a twin-screw extruder ("PCM-30" manufactured by Ikegai Co., Ltd., cylinder: split-combined barrel system, screw length: 65 cm), a material supply speed of 5 kg / hour, screw Melt kneading was performed at a rotational speed of 150 rpm. The twin screw extruder (PCM-30) controls a cylinder, a hopper with a feeder (quantitative supply device) for supplying material into the cylinder, two screws arranged in the cylinder, and the cylinder temperature. With a heater for. The distance between the material inlet and the material outlet of the twin screw extruder (PCM-30) was about 65 cm. Moreover, the sheet-like sheet | seat discharged | emitted from the twin-screw extruder (PCM-30) by arrange | positioning a rolling roll (accessory of "PCM-30" by Ikegai Co., Ltd.) near the discharge port of a twin-screw extruder. The melt-kneaded material was conveyed by a belt conveyor and immediately passed through a rolling roll. During the melt-kneading, the heater of the twin-screw extruder is controlled so that the temperature of the material inlet of the twin-screw extruder is set to the temperature shown in “Inlet temperature” in Table 1 and the temperature of the material outlet of the twin-screw extruder is Each was adjusted to the temperature shown in “Outlet temperature” in Table 1. For example, in the production of toner TA-1, the temperature of the material inlet of the twin screw extruder was 100 ° C. and the temperature of the material outlet of the twin screw extruder was 60 ° C. during melt kneading.

Subsequently, the kneaded material discharged from the material outlet of the twin-screw extruder was cooled while being rolled with a rolling roll. Subsequently, the rolled kneaded product was coarsely pulverized using (“Rotoplex 16/8” manufactured by Toa Machinery Co., Ltd.). Subsequently, the obtained coarsely pulverized product was finely pulverized using an impact plate type pulverizer (“Ultrasonic Jet Mill Type I” manufactured by Nippon Pneumatic Industry Co., Ltd.). Subsequently, the obtained finely pulverized product was classified using a classifier (wind classifier using the Coanda effect: “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 6.0 μm was obtained.

(Formation of shell layer)
A 1 L three-necked flask equipped with a thermometer and a stirring blade was prepared, and the flask was set in a water bath. Subsequently, 300 mL of ion-exchanged water was put in the flask, and the temperature in the flask was kept at 30 ° C. using a water bath. Subsequently, dilute hydrochloric acid was added to the flask to adjust the pH of the flask contents to 4.

  Subsequently, a shell material (any of shell materials S-1 and S-2) shown in Table 1 was added to the flask, and the contents of the flask were stirred to dissolve the resin raw material in the aqueous medium. The amount of shell material S-1 added was 35 mL. The addition amount of the shell material S-2 was 6 mL. Specifically, in the production of toner TA-5, 6 mL of shell material S-2 (Nicalac MX-280) is added, and in the production of other toners, 35 mL of shell material S-1 (milben resin SM-607) is added. Added.

  Subsequently, 300 g of the toner core prepared by the above-described procedure was added into the flask, and the flask contents were stirred for 1 hour under the conditions of a rotation speed of 200 rpm and a temperature of 40 ° C. Subsequently, 300 mL of ion exchange water was added to the flask, and the temperature in the flask was increased to 70 ° C. at a rate of 1.0 ° C./min while stirring the flask contents at a rotation speed (stirring blade) of 100 rpm. The flask contents were stirred for 2 hours under the conditions of 70 ° C. and rotation speed (stirring blade) of 100 rpm. As a result, a shell layer was formed on the surface of the toner core, and a dispersion of toner base particles was obtained. Subsequently, the pH of the toner mother particle dispersion was adjusted to 7 using sodium hydroxide (neutralized), and the toner mother particle dispersion was cooled to room temperature (about 25 ° C.).

(Washing process)
The dispersion of toner base particles obtained as described above was filtered (solid-liquid separation) using a Buchner funnel. As a result, toner base particles in the form of wet cake were obtained. Thereafter, the obtained wet cake-like toner base particles were dispersed again in ion-exchanged water. Dispersion and filtration were repeated a total of 5 times to wash the toner base particles.

(Drying process)
Subsequently, the washed toner base particles (powder) were dispersed in an aqueous ethanol solution having a concentration of 50% by mass to obtain a slurry of toner base particles. Subsequently, the toner base particles in the slurry were removed under the conditions of a hot air temperature of 45 ° C. and a blower air volume of 2 m ³ / min. Dried. As a result, dried toner base particles (powder) were obtained.

(External addition process)
Using an FM mixer (“FM-10” manufactured by Nippon Coke Kogyo Co., Ltd.), 100 parts by mass of toner base particles, 1.0 part by mass of hydrophobic silica particles (powder) prepared by the above procedure, 1.0 parts by mass of conductive titanium oxide particles (powder) prepared by the procedure, colloidal silica particles ("CAB-O-SIL (registered trademark) TG-C321" manufactured by Cabot Corporation), surface treatment agent: triethoxyoctylsilane The number average primary particle size: about 70 nm) is mixed with 1.0 part by mass at a rotational speed of 3500 rpm for 5 minutes to attach external additives (silica particles and titanium oxide particles) to the surface of the toner base particles. It was. Thereafter, the obtained powder was sieved using a 200-mesh (aperture 75 μm) sieve. As a result, toners (toners TA-1 to TA-6 and TB-1 to TB-7) containing a large number of toner particles were obtained.

  The toner particles contained in each of toners TA-1 to TA-6 and TB-1 to TB-7 obtained as described above are respectively CPES dispersions (specifically, dispersions of crystalline polyester resin domains). Contained. Table 4 shows the CR minor axis diameter, CR major axis diameter, CR aspect ratio, and CR compatible domain ratio measured for the CPES dispersion of each toner. The CR compatible domain is a crystalline resin domain that satisfies the conditions of a minor axis diameter of 50 nm to 200 nm and an aspect ratio of 4 to 20.

  For example, for toner TA-1, the CR minor axis diameter was 58 nm, the CR major axis diameter was 296 nm, the CR aspect ratio was 5.1, and the ratio of CR compatible domains was 93% by number. The respective measurement methods for the CR dimension value (specifically, the CR minor axis diameter, the CR major axis diameter, and the CR aspect ratio) and the ratio of the CR compatible domain were as follows.

(Cross section of toner particles)
A toner (measuring object: any of toners TA-1 to TA-6 and TB-1 to TB-7) is placed in a visible light curable resin (“Aronix (registered trademark) D-800” manufactured by Toagosei Co., Ltd.). The dispersion was dispersed and the resin was cured by UV irradiation to obtain a cured product. Thereafter, a knife for preparing an ultrathin section (“Sumiknife (registered trademark)” manufactured by Sumitomo Electric Industries, Ltd .: a diamond knife having a blade width of 2 mm and a blade tip angle of 45 °) and an ultramicrotome (“EM UC6” manufactured by Leica Microsystems) By cutting the cured product using, a thin piece having a thickness of 200 nm was produced. The resulting flakes were dyed on a copper mesh by exposure in the vapor of an aqueous ruthenium tetroxide solution for 20 minutes.

  Subsequently, using a transmission electron microscope (TEM) (“JEM-2000FX” manufactured by JEOL Ltd.), a bright field image of a cross section of the thin sample was taken under the conditions of an acceleration voltage of 80 kV, a magnification of 30000 times, and a field number of 5. did.

<Method for measuring CR dimension value and ratio of CR conforming domain>
By analyzing the photographed image obtained as described above using image analysis software (“WinROOF” manufactured by Mitani Corporation), a plurality of CR domains (in detail, each of which is a crystal The short axis diameter and the long axis diameter of each of the conductive polyester resin domains were measured. For each CR domain, the aspect ratio (= major axis diameter / minor axis diameter) was obtained by dividing the major axis diameter by the minor axis diameter. The dimension values (CR minor axis diameter, CR major axis diameter, and CR aspect ratio) of all CR domains in the five fields of view were measured. Then, the arithmetic average value of the measured CR dimension values (that is, CR minor axis diameter, CR major axis diameter, and CR aspect ratio) is used as the CR dimension value of the toner to be measured (that is, CR minor axis diameter, CR aspect ratio). Major axis diameter and CR aspect ratio). Whether or not each of the CR domains in the five fields of view corresponds to a CR conforming domain (specifically, a CR domain satisfying the condition that the minor axis diameter is 50 nm to 200 nm and the aspect ratio is 4 to 20). Judged. The total number of CR domains in the five fields was then divided by the number of CR matched domains to obtain the percentage of CR matched domains.

[Evaluation method]
The evaluation method of each sample (toners TA-1 to TA-6 and TB-1 to TB-7) is as follows.

(Heat resistant storage stability)
3 g of toner (evaluation object: any of toners TA-1 to TA-6 and TB-1 to TB-7) is put in a 20 mL polyethylene container, and the container is tapped for 5 minutes, and then 55 ° C. And allowed to stand for 8 hours in a thermostatic chamber set to. Thereafter, the toner taken out from the thermostat was cooled to room temperature (about 25 ° C.) to obtain an evaluation toner.

Subsequently, the obtained toner for evaluation was placed on a sieve having a known mass of 300 mesh (aperture 48 μm). Then, the mass of the sieve containing the toner was measured, and the mass of the toner on the sieve (that is, the mass W ₁ of the toner before sieving) was determined. Subsequently, a sieve is set in a powder property evaluation apparatus (“Powder Tester (registered trademark)” manufactured by Hosokawa Micron Co., Ltd.), and according to the manual of the powder tester, the sieve is vibrated for 30 seconds under the condition of the rheostat scale 5 to evaluate toner. Was sieved. Then, after sieving, the mass of the sieve containing the toner was measured to determine the mass of toner remaining on the sieving (that is, the mass W ₂ of the toner after sieving). Then, based on the mass W ₁ of the toner before sieving and the mass W ₂ of the toner after sieving, the toner aggregation rate W ₀ (unit: mass%) was determined according to the following formula.
W ₀ = 100 × W ₂ / W ₁

When the toner aggregation rate W ₀ was less than 20% by mass, it was evaluated as “good”, and when the toner aggregation rate W ₀ was 20% by mass or more, it was evaluated as “poor” (not good).

(Preparation of two-component developer)
100 parts by mass of developer carrier (carrier for “FS-C5300DN” manufactured by Kyocera Document Solutions Co., Ltd.) and toner (evaluation object: any of toner TA-1 to TA-6 and TB-1 to TB-7) 10 parts by mass were mixed for 30 minutes using a ball mill to obtain a developer for evaluation (specifically, a two-component developer).

(Low temperature fixability)
As an evaluator, a printer having a Roller-Roller type heating / pressing type fixing device (nip width: 8 mm) (evaluator capable of changing the fixing temperature by modifying “FS-C5300DN” manufactured by Kyocera Document Solutions Co., Ltd.) ) Was used. The developer for evaluation (two-component developer prepared as described above) is charged into the developing device of the evaluation machine, and the toner for replenishment (evaluation objects: toners TA-1 to TA-6 and TB-1 to TB-7). Was put into the toner container of the evaluation machine.

An image having a size of 25 mm × 25 mm and a printing rate of 10% under the conditions of a temperature of 23 ° C. and a humidity of 50% RH under the conditions of a linear velocity of 240 mm / second and a toner applied amount of 1.0 mg / cm ² using the evaluation machine. Was formed on paper (A4 size printing paper) having a basis weight of 90 g / m ² . Subsequently, the paper on which an image (specifically, an unfixed image) was formed was passed through the fixing device of the evaluation machine. The nip passage time was 30 milliseconds.

  In the evaluation of the low-temperature fixability of the toner, the measurement range of the fixing temperature was 80 ° C. or higher and 160 ° C. or lower. The fixing temperature of the fixing device was increased from 80 ° C. by 5 ° C., and the minimum temperature (minimum fixing temperature) at which the solid image (toner image) can be fixed on the paper was measured. Whether or not the toner could be fixed was confirmed by a rubbing test as shown below. Specifically, the evaluation paper passed through the fixing device was bent so that the surface on which the image was formed was on the inside, and the image on the crease was rubbed 10 times with a 1 kg weight coated with a cloth. Subsequently, the paper was spread and the bent portion of the paper (the portion where the solid image was formed) was observed. Then, the length (peeling length) of toner peeling at the bent portion was measured. The lowest temperature among the fixing temperatures at which the peeling length was less than 1 mm was defined as the lowest fixing temperature. When the minimum fixing temperature was 120 ° C. or lower, it was evaluated as “good”, and when the minimum fixing temperature exceeded 120 ° C., it was evaluated as “poor” (not good).

[Evaluation results]
Table 5 shows the evaluation results of heat-resistant storage stability (toner aggregation rate W ₀ ) and low-temperature fixability (minimum fixing temperature) for toners TA-1 to TA-6 and TB-1 to TB-7.

  The toners TA-1 to TA-6 (toners according to Examples 1 to 6) each had the above-described basic configuration. Specifically, each of the toners TA-1 to TA-6 includes a plurality of toner particles each including a toner core and a shell layer covering the surface of the toner core. The toner core contained a melt-kneaded product of an amorphous resin and a crystalline resin. The shell layer contained a thermosetting resin (specifically, a melamine resin or a urea resin). The melt-kneaded product contained a plurality of crystalline resin domains. Of the plurality of crystalline resin domains contained in the toner particles, the ratio of domains satisfying the conditions of the minor axis diameter of 50 nm to 200 nm and the aspect ratio of 4.0 to 20.0 was 80% by number or more ( (See Table 4).

Each method for producing toners TA-1 to TA-6 (toners according to Examples 1 to 6) includes a melt-kneading step, a pulverizing step, and a shell layer forming step as shown below. . In the melt-kneading step, a toner material containing a crystalline resin and an amorphous resin is charged into a screw extruder, and the screw rotation speed of the screw extruder is 50 rpm or more and 500 rpm or less (specifically, 150 rpm). The distance between the material inlet and the material outlet of the screw extruder is 30 cm or more and 300 cm or less (specifically, about 65 cm), and the temperature of the material inlet is “crystalline resin melting point + 20 ° C.” or more and “crystalline resin” Toner material by a screw extruder under the condition that the temperature of the material outlet is not more than “temperature of the material inlet part−60 ° C.” and not more than “temperature of the material inlet part−40 ° C.”. Were melt-kneaded to obtain a melt-kneaded product (see Table 1). The SP value of the amorphous resin is larger than the SP value of the crystalline resin, and the difference between the SP value of the amorphous resin and the SP value of the crystalline resin is 1.0 (cal / cm ³ ) ^1/2 or more. 1.4 (cal / cm ³ ) ^1/2 or less (see Tables 1 to 3). In the pulverization step, the melt-kneaded product was pulverized to obtain a pulverized product containing a plurality of particles. In the shell layer forming step, the pulverized product obtained in the pulverizing step is put in a liquid, and in the liquid, on each surface of a plurality of particles contained in the pulverized product, a thermosetting resin (specifically, a melamine resin or A shell layer containing (urea-based resin) was formed.

  As shown in Table 5, toners TA-1 to TA-6 (toners according to Examples 1 to 6) were excellent in heat-resistant storage stability and low-temperature fixability, respectively.

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

DESCRIPTION OF SYMBOLS 100 Toner particle 10 Toner core 11 Amorphous resin 12 CR domain 13 Release agent domain 21 Shell layer 22 External additive particle 30 Twin screw extruder 31 Hopper 32 Cylinder 33 Screw 34 Heater P1 Material inlet part P2 Material outlet part S1, S2 Temperature sensor

Claims (6)

A toner comprising a plurality of toner particles comprising a toner core and a shell layer covering the surface of the toner core,
The toner core contains a melt-kneaded product of an amorphous resin and a crystalline resin,
The shell layer contains a thermosetting resin,
The melt-kneaded product includes a plurality of crystalline resin domains,
Of the plurality of crystalline resin domains contained in the toner particles, the ratio of domains satisfying the conditions of the minor axis diameter of 50 nm to 200 nm and the aspect ratio of 4.0 to 20.0 is 80% by number or more. ,toner. The difference between the SP value of the non-crystalline resin and the SP value of the crystalline resin is 1.0 (cal / cm ³ ) ^1/2 or more and 1.4 (cal / cm ³ ) ^1/2 or less in absolute value. The toner according to claim 1, wherein The short axis diameter of the plurality of crystalline resin domains is a number average value of 50 nm or more and 200 nm or less,
The toner according to claim 2, wherein an aspect ratio of the plurality of crystalline resin domains is 4.0 to 20.0 in terms of a number average value.   The toner according to claim 1, wherein the plurality of crystalline resin domains are dispersed in the toner particles in a state where the major axis direction is aligned.   The toner according to claim 1, wherein the shell layer contains an aminoaldehyde resin as the thermosetting resin. A toner material containing a crystalline resin and an amorphous resin is charged into a screw extruder, and the screw rotation speed of the screw extruder is not less than 50 rpm and not more than 500 rpm, and the material inlet portion of the screw extruder and the screw extruder And the temperature of the material inlet portion is not less than “the melting point of the crystalline resin + 20 ° C.” and not more than “the melting point of the crystalline resin + 40 ° C.”, and The toner material is melted and kneaded by the screw extruder under the condition that the temperature of the material outlet is not less than “temperature of the material inlet -60 ° C.” and not more than “temperature of the material inlet -40 ° C.” A melt-kneading step for obtaining a kneaded product;
Crushing the melt-kneaded product to obtain a pulverized product containing a plurality of particles;
A shell layer forming step of putting the pulverized product in a liquid and forming a shell layer containing a thermosetting resin on the surface of each of the plurality of particles included in the pulverized product in the liquid;
Including
The difference between the SP value of the non-crystalline resin and the SP value of the crystalline resin is 1.0 (cal / cm ³ ) ^1/2 or more and 1.4 (cal / cm ³ ) ^1/2 or less in absolute value. A method for producing a toner.