JP2010169895A - Method of producing negative charge type nonmagnetic mono-component toner and negative charge type nonmagnetic mono-component toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing a negative charge type nonmagnetic mono-component toner which obtains a high quality printed image free of fogging and void generation, because the toner has adequate fluidity and prevents exposure of a release agent to a toner particle surface to thereby prevent the release agent from sticking or fixing on a charging blade and a photoreceptor. <P>SOLUTION: The negative charge type nonmagnetic mono-component toner is obtained by adding a predetermined amount of silica fine particles to toner particles; mixing and stirring; further adding a predetermined amount of silica fine particles; mixing and stirring to obtained a particle mixture; heat-treating the particle mixture so that the toner particles contained therein achieve a predetermined circularity; further adding alumina particles having a predetermined volume average particle diameter; and mixing and stirring. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a nonmagnetic one-component negatively chargeable toner used in an image forming apparatus such as a copying machine or a printer that forms an image by a nonmagnetic one-component developing system, and a nonmagnetic one-component produced by the method. The present invention relates to a negatively chargeable toner.

  As the performance of computers, OA (Office Automation) devices and the like improves, various printers and copiers capable of outputting images such as high-resolution character images and graphic images are commercially available as information output devices. As an image forming method in these apparatuses, an electrostatic charge image is formed on an image carrier, and the electrostatic charge image is developed using a toner for electrophotography (hereinafter sometimes simply referred to as “toner”) to form a toner image. A so-called electrophotographic method in which this toner image is transferred to a recording medium and fixed is widely used.

  The electrophotographic toner is in the form of fine particles containing a binder, a colorant, a release agent, a charge control agent, and the like.

  A pulverization method is known as a kind of method for producing an electrophotographic toner. In the pulverization method, first, toner materials such as a binder, a release agent, a colorant and a charge control agent are mixed and melt-kneaded, and the resulting melt-kneaded product is cooled, then pulverized and classified. This is a method for obtaining particles, and has an advantage that an electrophotographic toner can be efficiently produced with relatively simple equipment. In the pulverization method, more specifically, after classification, an external additive such as a fluidizing agent and a resistance control agent is further externally added to the toner particles, and mixed with a mixer to adhere the external additive to the surface of the toner particles. A photographic toner is obtained.

  Thus, the electrophotographic toner produced by producing toner particles by pulverizing the melt-kneaded product has a problem that the shape of the particles becomes irregular and the fluidity is not sufficient. When such toner is used, for example, in the non-magnetic one-component developing method, the toner transportability to the developing sleeve is not sufficient, and tracking failure and jitter are likely to occur. “Following tracking” refers to a phenomenon in which toner replenishment (supply) cannot follow the rotation of the developing sleeve and the image density decreases. “Jitter” is a phenomenon in which the developing sleeve and toner transport speed are disturbed by a mechanical load, and stripes of light and shade are generated in an image.

  Further, an electrophotographic toner composed of toner particles having an irregular particle shape causes fogging because the charge amount becomes non-uniform and the charge amount decreases. Here, “fogging” is a phenomenon in which image quality deteriorates due to transfer of toner to a non-image portion of a printed image.

As a technique for improving the fluidity of electrophotographic toner, a raw material mixture containing toner particles formed by pulverization and silica fine particles having a specific surface area of 80 m ² / g or more in a specific ratio is specified. The applicant of the present application has proposed a method of obtaining toner for electrophotography by heat treatment under specific conditions using a hot air processing apparatus (see, for example, Patent Document 1).

2008-119645 gazette

  According to the technique disclosed in Patent Document 1, it is possible to suppress the fusion of toner particles and the adhesion of silica fine particles to the surface of the toner particles, and to form the toner particles into a shape that is easy to flow. An electrophotographic toner can be obtained.

  However, the release agent may be exposed on the toner particle surface. The release agent exposed on the surface of the toner particles directly attaches to or adheres to the charging blade or the surface of the photosensitive member, thereby easily causing image defects such as white spots. In addition, when there are many coarse particles generated by fusing toner particles together, they adhere to the charging blade and image defects such as white spots are likely to occur.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide sufficient fluidity and prevent the release agent from adhering or fixing to a charging blade or a photoreceptor, thereby preventing image quality. The present invention is to provide a method for producing a nonmagnetic one-component negatively chargeable toner having a good toner and a nonmagnetic one-component negatively charged toner produced by the method.

  As a result of intensive studies, the inventors have added a predetermined amount of silica fine particles to the toner particles, mixed and stirred, then further added a predetermined amount of silica fine particles and mixed and stirred to obtain a particle mixture, and the particle mixture. The toner particles contained in the toner are heat-treated so as to have a predetermined circularity, and further, alumina particles having a predetermined volume average particle diameter are added and mixed and stirred, so that the release agent adheres to or adheres to the charging blade or the photoreceptor. The present inventors have found that a non-magnetic one-component negatively chargeable toner that can prevent the occurrence of toner can be obtained.

That is, the present invention contains 1 to 3 parts by mass of silica fine particles with respect to 100 parts by mass of toner particles containing a binder, a colorant, a release agent, and a negatively chargeable charge control agent. In addition, mixing and stirring, a first stirring step of obtaining coated particles that are toner particles coated with silica fine particles on the surface;
A second stirring step of adding 0.2 to 1 part by mass of silica fine particles to 100 parts by mass of the toner particles and mixing and stirring to obtain a particle mixture of the coated particles and silica fine particles;
In the circularity distribution of the toner particles contained in the particle mixture obtained in the second stirring step, the circularity (C10) when the integrated value of the number frequency from the low circularity is 10% is 0.925 or more, And the heat treatment process of heat-treating the particle mixture so that the circularity (C50) when the integrated value of the number frequency from the low circularity is 50% is 0.97 or more,
A non-magnetic one-component negative charging comprising: a post-stirring step of adding alumina particles having a volume average particle size of 0.1 to 3 μm to the particle mixture heat-treated in the heat-treating step, followed by mixing and stirring. This is a method for producing a functional toner.

Further, the present invention provides the heat treatment step,
An air inlet for taking in cooling air in the upper part, and a hot air treatment tank in which the particle mixture and hot air are supplied from the upper part to the internal space;
A hot air injection nozzle for injecting hot air from the upper part of the hot air treatment tank toward the internal space;
A raw material injection nozzle for injecting the particle mixture toward the hot air injected from the hot air injection nozzle, wherein the lower end opening where the raw material outlet from which the particle mixture is injected is formed is injected with hot air from the hot air injection nozzle. A raw material injection nozzle provided on the inner side of the lower end opening where the hot air outlet is formed, and located above the lower end opening of the hot air injection nozzle;
A heat insulating mechanism that is provided so as to be separated from the raw material injection nozzle and surround the raw material injection nozzle, and includes a cooling jacket in which a flow path through which the refrigerant flows is formed, and insulates the raw material injection nozzle and the hot air injection nozzle; ,
A collision member provided below the lower end opening of the raw material injection nozzle and spaced from the raw material injection nozzle;
Dispersed from the opening at the lower end of the air injection flow path formed by the outer surface portion of the material injection nozzle and the inner surface portion of the cooling jacket of the heat insulation mechanism toward the surface portion facing the lower end opening of the material injection nozzle of the collision member The particle mixture is heat-treated using a hot-air treatment device provided with air jetting means for jetting air for use.

  The present invention also provides a nonmagnetic one-component negatively chargeable toner manufactured by the above-described method for manufacturing a nonmagnetic one-component negatively chargeable toner.

  According to the present invention, a nonmagnetic one-component negatively chargeable toner (hereinafter sometimes simply referred to as “toner”) is produced through a first stirring step, a second stirring step, a heat treatment step, and a post-stirring step. In the first stirring step, 1 to 3 parts by mass of silica fine particles are added to 100 parts by mass of toner particles and mixed and stirred to obtain coated particles which are toner particles having silica fine particles coated on the surface. As a result, it is possible to obtain a toner in which the exposed part of the release agent on the surface of the toner particles is coated with silica fine particles. For this reason, it is possible to prevent the adhered or fixed matter derived from the release agent from being generated on the surface of the charging blade or the photoreceptor, and a high-quality printed image can be obtained.

  Next, in the second stirring step, 0.2 to 1 part by mass of silica fine particles is further added to 100 parts by mass of the toner particles and mixed and stirred to obtain a particle mixture. As a result, in the coated particles obtained in the first stirring step, the silica particles are interposed between the toner particles whose surfaces are coated with the silica particles, and the toner particles are fused with each other during the heat treatment in the heat treatment step. Can be prevented. As described above, the toner in which the fusion between the toner particles is prevented is not fixed to the charging blade, and a high-quality printed image can be obtained.

  Next, in the heat treatment step, the toner particles contained in the particle mixture obtained in the second stirring step are particles having a circularity (C10) of 0.925 or more and a circularity (C50) of 0.97 or more. The particle mixture is heat treated so that As described above, the toner obtained by heat treatment so as to obtain toner particles having a circularity (C50) of 0.97 or more becomes a toner having sufficient fluidity and can prevent the occurrence of fog. . In addition, the toner obtained by heat treatment so that the toner particles have a circularity (C10) of 0.925 or more becomes a toner with little fusing between the toner particles, does not adhere to the charging blade, and is a high-quality printed image. Can be obtained.

  Next, in the post-stirring step, alumina particles having a volume average particle size of 0.1 to 3 μm are added to the particle mixture that has been heat-treated in the heat-treating step and mixed and stirred. As a result, the charge amount of the toner can be increased to prevent the occurrence of fog on the photosensitive member.

  As described above, the toner is manufactured through the first stirring step, the second stirring step, the heat treatment step, and the post-stirring step, thereby having sufficient fluidity and preventing the exposure of the release agent on the toner particle surface. In addition, since the amount of charge is increased by suppressing fusion between toner particles, a toner capable of obtaining a high-quality printed image in which white spots, fogging, and the like are prevented can be manufactured. it can.

  In addition, according to the present invention, in the heat treatment step, a toner in which the toner particles have a predetermined circularity can be obtained by heat-treating the particle mixture using a specific hot air treatment apparatus.

  Further, according to the present invention, the nonmagnetic one-component negatively chargeable toner is produced by the excellent method for producing a nonmagnetic one-component negatively chargeable toner as described above. Therefore, it has sufficient fluidity, prevents exposure of the release agent on the surface of the toner particles, suppresses fusion between the toner particles, can increase the charge amount, and causes white spots and fogging. Thus, a non-magnetic one-component negatively chargeable toner capable of obtaining a high-quality printed image that is prevented from being formed is realized.

3 is a flowchart showing a procedure for manufacturing a nonmagnetic one-component negatively chargeable toner according to an embodiment of the present invention. It is sectional drawing which shows the structure of the hot air processing apparatus 1 used at the heat processing process of this embodiment. It is sectional drawing which expands and shows the hot air injection nozzle 12 and the raw material injection nozzle 13 of the hot air processing apparatus 1 shown in FIG. 6 is a graph illustrating a circularity distribution of toner particles.

  The nonmagnetic one-component negatively chargeable toner of the present invention includes toner particles, silica fine particles, and alumina particles. The nonmagnetic one-component negatively chargeable toner manufacturing method according to an embodiment of the present invention includes a toner particle generation step, a first stirring step, a second stirring step, a heat treatment step, and a post-stirring step. FIG. 1 is a flowchart showing a procedure for manufacturing a nonmagnetic one-component negatively chargeable toner according to an embodiment of the present invention.

[Toner particle generation process]
In the toner particle generation step of step s1, toner particles are generated by pulverization. The toner particles contain a binder, a colorant, a release agent, and a negatively chargeable charge control agent.

  The material for the binder constituting the toner particles is not particularly limited, and conventionally known materials can be used. Specific examples include styrene copolymers such as polystyrene, styrene-methyl acrylate copolymer, styrene-acrylonitrile copolymer, and resin materials such as polyester resin and epoxy resin. These binder materials can be used singly or in combination of two or more. Among these, it is particularly preferable to use a polyester resin because it is easy to be colored and a toner having a clear color can be obtained. Therefore, in this embodiment, a binder made of a polyester resin is used.

  The material of the colorant constituting the toner particles is not particularly limited, and conventionally known materials can be used. Specifically, examples of the black colorant material include carbon black and magnetic powder exhibiting black color. Examples of the cyan colorant material include copper phthalocyanine, methylene blue, and Victoria blue. Examples of magenta colorant materials include rhodamine dyes, dimethylquinacridone, dichloroquinacridone, and carmine red. Examples of yellow colorant materials include benzidine yellow and chrome yellow. Naphthol yellow, disazo yellow and the like.

  In this embodiment, the toner particles contain a release agent. By including a release agent in the toner particles, the offset resistance of the toner can be improved and the offset phenomenon can be made difficult to occur. The material of the release agent is not particularly limited, and conventionally known materials can be used. Specifically, for example, polyolefin wax such as polyethylene and polypropylene, carnauba wax, rice wax, sazol wax, montan ester wax And so on.

  In this embodiment, the toner particles contain a negatively chargeable charge control agent. By containing a negatively chargeable charge control agent in the toner particles, the toner can be charged efficiently. The material of the negatively chargeable charge control agent is not particularly limited, and conventionally known materials can be used. Specifically, nigrosine, basic dyes, metal complexes such as monoazo dyes, and carboxylic acids such as salicylic acid and dicarboxylic acid And metal complexes with metals such as chromium and iron, and organic dyes.

  In this embodiment, the toner particles are formed into particles by pulverization, and in the toner particle generation step, the above-described constituent materials are mixed using a high-speed stirrer such as a Henschel mixer, a super mixer, a turbine stirrer, or the like. After kneading using a kneader such as an extruder, the obtained kneaded product is obtained by pulverizing with a pulverizer. The pulverizer used for pulverizing the kneaded product is not particularly limited, and examples thereof include a jet mill and a turbo mill. Among these, it is preferable to use a rotor-type pulverizer that pulverizes using a rotor.

  Since the toner particles are heat-treated in a heat treatment step to be described later, a plurality of particles are not fused, and the surface of the toner particles is individually smoothed. Therefore, the size of the toner particles after the heat treatment can be obtained in the toner particle generation step. It is determined by the size of the toner particles. The toner particles after the heat treatment in the heat treatment step preferably have a volume average particle diameter of 4 μm to 15 μm, and more preferably 6 μm to 10 μm. Therefore, the toner particles to be subjected to the heat treatment step have a volume average particle diameter within the above-mentioned range as a preferable range of the volume average particle diameter of the toner particles after the heat treatment from the toner particles obtained by pulverization in the toner particle generation step. It is preferable to classify and use things by classification.

[First stirring step]
In the first stirring step of step s2, a predetermined amount of silica fine particles are added to the toner particles obtained in the toner particle generating step and mixed and stirred, and the silica fine particles are coated on the exposed portion of the release agent on the toner particle surface. Coated particles that are toner particles are obtained.

The silica fine particles used in the first stirring step are not particularly limited, but those having a BET specific surface area of at least 100 m ² / g which has been surface-treated with dimethyldichlorosilane, silicone oil, hexamethylene disilazane or the like are preferable. . The upper limit of the BET specific surface area of the silica fine particles is not particularly limited, but as a generally available silica fine particle, the upper limit of the BET specific surface area is about 400 m ² / g. Therefore, in the present embodiment, the BET specific surface area of the silica fine particles is 100 m ² / g or more and 400 m ² / g or less.

  The BET specific surface area of the silica fine particles is measured by the BET method. The “BET method” is a method for obtaining the specific surface area of a sample from the amount of gas adsorbed on the surface of the sample particle based on the theory proposed by Brunauer, Emmett and Teller. In the present embodiment, the specific surface area of the silica fine particles is measured using adsorption of nitrogen gas at the liquid nitrogen temperature.

  In the first stirring step, silica fine particles and toner particles are mixed and stirred using a high-speed mixing device to obtain coated particles. Examples of the high speed mixing apparatus include a Henschel mixer and a super mixer. The high-speed mixing device is not limited to these, and any device capable of mixing powder can be used as the high-speed mixing device.

  In this embodiment, silica fine particles are added in a mass ratio of 1 part by mass or more and 3 parts by mass or less to 100 parts by mass of toner particles in a mixing and stirring tank of a high speed mixing apparatus. At this time, it is preferable to add the toner particles and the silica fine particles so that the volume is 30% or more and 60% or less of the volume capacity of the mixing and stirring tank.

  Thus, in the first stirring step, the silica particles are added within a mass ratio range of 1 part by mass to 3 parts by mass with respect to 100 parts by mass of the toner particles, and are mixed and stirred to obtain the coated particles. In the particles, the exposed part of the release agent on the surface of the toner particles is coated with silica fine particles. For this reason, it is possible to prevent deposits or sticking substances derived from the release agent from being generated on the surface of the charging blade or the photoreceptor, and to obtain a high-quality printed image in which the occurrence of white spots or the like is prevented.

  In the first stirring step, if the amount of silica fine particles added to 100 parts by mass of the toner particles is less than 1 part by mass, the effect of suppressing the exposure of the release agent to the toner particle surfaces is not sufficient. In addition, when the amount of silica fine particles added to 100 parts by mass of toner particles exceeds 3 parts by mass, the coverage of the silica fine particles on the surface of the toner particles becomes too large, and the heat treatment in the heat treatment step described later is effectively performed by the heat treatment Toner particles having a circularity cannot be obtained.

  In the first stirring step, when the silica fine particles and the toner particles are mixed and stirred using a high-speed mixing device, the temperature of the mixing and stirring tank (chiller temperature of the high-speed mixing device) is set to 25 degrees or less, and high-speed mixing In the state where the peripheral speed of the tip of the stirring blade of the apparatus is set to 1800 to 3000 m / min, it is preferable to carry out mixing and stirring within a range of 3 minutes to 20 minutes. By mixing and stirring the silica fine particles and the toner particles under such conditions, toner particles (coated particles) whose surfaces are coated with the silica fine particles can be obtained.

[Second stirring step]
In the second stirring step of step s3, silica fine particles are further added in a mass ratio range of 0.2 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the toner particles, and mixing is performed using a high speed mixing device. Agitation is performed to obtain a particle mixture composed of toner particles (coated particles) whose surfaces are coated with silica fine particles obtained in the first stirring step and silica fine particles added in the second stirring step. As a result, the silica fine particles are interposed between the toner particles coated on the surface with the silica fine particles obtained in the first stirring step, thereby preventing the fusion of the toner particles during the heat treatment in the heat treatment step described later. be able to. As described above, the toner in which the fusion between the toner particles is prevented is not fixed to the charging blade, and a high-quality printed image can be obtained.

  In the second stirring step, if the addition amount of the silica fine particles is less than 0.2 parts by mass with respect to 100 parts by mass of the toner particles, the effect of preventing the fusion of the toner particles during the heat treatment in the heat treatment step described later is not sufficient. Absent. In addition, when the amount of silica fine particles added to 100 parts by mass of toner particles exceeds 1 part by mass, the running suitability decreases.

  The silica fine particles used in the second stirring step can be the same as the silica fine particles used in the first stirring step.

  In the second stirring step, the toner particles (coated particles) whose surfaces are coated with the silica fine particles obtained in the first stirring step and the silica fine particles added in the second stirring step are mixed using a high-speed mixing device. When stirring, the temperature of the mixing and stirring tank (chiller temperature of the high speed mixing device) is set to 25 degrees or less, and the peripheral speed of the tip of the stirring blade of the high speed mixing device is set to 1800 to 3000 m / min. It is preferable to carry out mixing and stirring within a range of from 3 minutes to 3 minutes. Under such conditions, by mixing and stirring the toner particles (coated particles) coated on the surface with the silica fine particles obtained in the first stirring step and the silica fine particles added in the second stirring step, a particle mixture is obtained. Obtainable.

[Heat treatment process]
In the heat treatment step of step s4, heat treatment is performed using a hot air treatment device so that the toner particles contained in the particle mixture obtained in the second stirring step have a predetermined circularity. FIG. 2 is a cross-sectional view showing the configuration of the hot air treatment apparatus 1 used in the heat treatment step of the present embodiment. FIG. 2 shows a cross-sectional configuration of the hot-air treatment tank 11 and the hot-air injection nozzle 12, and the raw material injection nozzle 13 and the hopper unit 17 are difficult to understand because the drawings are complicated and a front view is shown. FIG. 3 is an enlarged sectional view showing the hot air injection nozzle 12 and the raw material injection nozzle 13 of the hot air processing apparatus 1 shown in FIG.

  The hot air processing apparatus 1 includes a hot air processing tank 11, a hot air injection nozzle 12, a raw material injection nozzle 13, a heat insulation mechanism 14, a collision member 15, and an air injection means 16. As shown in FIG. 2, the hot air treatment tank 11 includes a substantially cylindrical treatment tank body 21 and a top plate 22 that closes an opening at the top of the treatment tank body 21. The processing tank main body 21 is disposed such that its axial direction coincides with the vertical direction. The vertical direction is defined as the Z1 direction, the opposite direction of the Z1 direction is defined as the Z2 direction, and the Z direction is defined as including the Z1 direction and the Z2 direction. The processing tank body 21 is formed in a tapered shape in which the opening diameter of the upper part is larger than the opening diameter of the lower part, and the intermediate part between the upper part and the lower part in the axial direction becomes smaller as the opening diameter approaches the lower part. .

  The top plate 22 is provided on the upper part of the processing tank main body 21. In the internal space of the hot air treatment tank 11 formed by the treatment tank body 21 and the top plate 22, the particle mixture and hot air obtained in the second stirring step are supplied from the upper part of the hot air treatment tank 11. The top plate 22 is formed in a substantially disc shape, a first air intake port is formed in the first intake port 23 at the center thereof, and a second air is formed in the second intake port 24 of the outer peripheral portion. An intake is formed. Cooling air is taken in through the first air inlet and the second air inlet.

  The hot air injection nozzle 12 is provided above the hot air treatment tank 11. The hot air injection nozzle 12 is formed to be bent in an L shape, and the opening end face of the lower end opening 25 where the hot air outlet that is one end thereof is formed is included in a virtual plane including the upper surface of the top plate 22. As described above, more specifically, the opening end face of the lower end opening 25 and the top face of the top plate 22 are arranged so that the positions in the Z direction coincide with each other. The hot air outlet of the hot air injection nozzle 12 and the first air intake port of the top plate 22 are formed in a circular shape, and the hot air injection nozzle 12 is arranged so that the axis of the hot air outlet coincides with the axis of the first air intake port. Has been placed. Hot air is injected into the hot air treatment tank 11 from the hot air outlet formed in the lower end opening 25.

  As shown in FIG. 3, the raw material injection nozzle 13 is provided so that the lower end opening 26 where the raw material outlet is formed is located on the inner side of the lower end opening 25 of the hot air injection nozzle 12. Moreover, the lower end opening part 26 of the raw material injection nozzle 13 is provided so as to be positioned above the lower end opening part 25 of the hot air injection nozzle 12, that is, on the Z2 direction side.

  The upper part of the raw material injection nozzle 13 passes through the bent part 37 of the hot air injection nozzle 12, and the hopper part 17 for storing the particle mixture is provided on the upper part facing the outside. A diffuser 27 is provided below the hopper 17, and an air injection nozzle 28 that injects compressed air toward the diffuser 27 is provided in the hopper 17. When compressed air is injected from the air injection nozzle 28 to the diffuser 27, the particle mixture stored in the hopper 17 is sucked into the raw material injection nozzle 13 and mixed with the compressed air, and the solid-gas mixed fluid is supplied to the raw material injection nozzle 13. The hot air is ejected from the raw material outlet of the lower end opening 26 toward the center of the hot air ejected from the hot air ejecting nozzle 12.

  The collision member 15 is provided at a distance from the raw material injection nozzle 13 below the raw material injection nozzle 13, more specifically below the lower end opening 26 of the raw material injection nozzle 13. By providing the collision member 15, the particle mixture injected from the raw material injection nozzle 13 can be dispersed by collision. The collision member 15 is formed in a disk shape.

  The heat insulation mechanism 14 is provided outside the raw material injection nozzle 13. By providing the heat insulation mechanism 14, the raw material injection nozzle 13 and the hot air injection nozzle 12 are insulated, and the temperature of the raw material injection nozzle 13 rises above the melting point of the toner particles by contact with the hot air flowing in the hot air injection nozzle 12. This can be prevented. This can prevent the toner particles from melting and adhering to and depositing on the inner surface of the raw material injection nozzle 13.

  The heat insulation mechanism 14 includes a cooling jacket 29 provided so as to be separated from the material injection nozzle 13 and surround the material injection nozzle 13. The heat insulation mechanism 14 includes an inner cylinder part 14a provided outside the raw material injection nozzle 13 and an outer cylinder part 14b provided outside the inner cylinder part 14a. The inner cylinder part 14a and the outer cylinder part 14b Thus, a cooling jacket 29 is formed. The refrigerant flows through the flow path of the cooling jacket 29, which is the gap between the inner cylinder portion 14a and the outer cylinder portion 14b. The heat insulation mechanism 14 has a refrigerant inlet 30 formed in the lower part of the cooling jacket 29 and a refrigerant outlet 31 formed in the upper part. The refrigerant is supplied from the refrigerant inlet 30 into the cooling jacket 29 and the raw material injection nozzle 13 is The refrigerant is cooled, and the cooled refrigerant flows out from the refrigerant outlet 31. As the refrigerant, a -15 ° C. ethylene glycol 50% aqueous solution is used. The refrigerant is not limited to this, and water or air may be used as the refrigerant.

  An air injection passage 32 is formed between the inner peripheral surface portion of the inner cylinder portion 14 a of the heat insulating mechanism 14 and the outer peripheral surface portion of the raw material injection nozzle 13. The air injection passage 32 is formed by an inner peripheral surface portion of the inner cylinder portion 14 a that is an inner surface portion of the cooling jacket 29 and an outer peripheral surface portion that is an outer surface portion of the raw material injection nozzle 13. An air inlet 33 is formed in the upper part of the air injection passage 32, and a gas as dispersion air is supplied from the air inlet 33 into the air injection passage 32. The dispersion air supplied into the air injection passage 32 flows downward in the air injection passage 32, that is, in the Z1 direction, and from the lower end opening 34, the lower end of the raw material injection nozzle 13 which is the upper surface portion of the collision member 15. Injected toward the surface facing the opening 26.

  The hot air treatment device 1 injects hot air from the hot air injection nozzle 12 into the hot air treatment tank 11, injects dispersion air from the air injection passage 32 to the collision member 15, and causes the refrigerant to flow into the cooling jacket 29. In the state, a solid-gas mixed fluid of the particle mixture and compressed air is ejected from the raw material ejection nozzle 13.

  When the particle mixture is injected from the raw material injection nozzle 13, the injected particle mixture collides with the collision member 15. The particle mixture is dispersed in the hot air by the collision and air for dispersion ejected from the air ejection passage 32 toward the upper surface of the collision member 15. As a result, the particle mixture can be effectively brought into contact with hot air, so that the heat treatment can be performed efficiently. Moreover, the hot air injected from the hot air injection nozzle 12 has a higher temperature in the central portion thereof, that is, in the central portion of the hot air outlet than in the other portions. In this embodiment, the hot air outlet axis coincides with the raw material outlet axis. Then, since the particle mixture is jetted to the hot air at a high temperature, the particle mixture can be effectively contacted with the hot air, and the toner particles are heat-treated by the contact and coated on the toner particle surface. Negatively chargeable silica fine particles can be immobilized.

  In the present embodiment, the first and second air intakes are formed in the top plate 22, and cooling air flows into the hot air treatment tank 11 from the first air intake and the second air intake, By this cooling air, the heat-treated particle mixture can be quickly cooled. Further, since the inner surface of the hot air treatment tank 11 is cooled by the cooling air flowing in from the second air intake, the heat-treated particle mixture does not adhere to the inner surface of the hot air treatment tank 11, and the lower part of the hot air treatment tank 11. It is discharged from the outlet formed.

  In the present embodiment, the opening end face of the lower end opening 26 of the raw material injection nozzle 13 is provided so as to be positioned above the opening end face of the lower end opening 25 of the hot air injection nozzle 12. That is, the lower end opening 26 of the raw material injection nozzle 13 is provided so as to be positioned above the lower end opening 25 of the hot air injection nozzle 12 by the dimension H. Thereby, the particle mixture injected from the raw material injection nozzle 13 can immediately come into contact with the hot air, and the particle mixture can flow for a long time in the high temperature region of the hot air. It can be heat treated.

  As the hot air treatment apparatus 1 shown in FIGS. 2 and 3, for example, a spheronization treatment apparatus disclosed in Japanese Patent Application Laid-Open No. 2004-276016 can be used. Specifically, a surface from Nippon Pneumatic Industry Co., Ltd. Examples include Meteorenbo (trade name) commercially available as a reformer. In the spheronization processing apparatus disclosed in Japanese Patent Application Laid-Open No. 2004-176016, the reaction tank corresponds to a hot air processing tank.

  As described above, in the heat treatment step, heat treatment is performed using the hot air treatment device 1 so that the toner particles contained in the particle mixture obtained in the second stirring step have a predetermined circularity.

  The circularity of the toner particles will be specifically described with reference to FIG. FIG. 4 is a graph for explaining the circularity distribution of toner particles. In FIG. 4, the horizontal axis indicates the circularity of the toner particles, and the vertical axis indicates the integrated value (%) of the number frequency.

  As shown in FIG. 4, in the heat treatment step, in the circularity distribution of the toner particles contained in the particle mixture obtained in the second stirring step, the circularity C10 when the integrated value of the number frequency from the low circularity is 10%. Is 0.925 or more (preferably 0.94 or more), and the circularity C50 when the integrated value of the number frequency from the low circularity is 50% is 0.97 or more (preferably 0.975 or more, more The particle mixture is heat-treated so that it is preferably 0.98 or more. Thus, the toner obtained by heat treatment so that the toner particles have a predetermined circularity becomes a toner capable of preventing the occurrence of fogging, white spots and the like.

Here, the circularity of the toner particles is a value calculated by the following formula (1), and the toner particles having a circularity of 1.00 are true spherical.
Circularity = (circle circumference obtained from equivalent circle diameter of toner particle projection image)
/ (Perimeter of toner particle projection image) (1)

  In addition, after the heat treatment in the hot air treatment apparatus 1, the toner particles having the above-described circularity range may be sorted by classification with a classifier.

[Post-stirring step]
In the post-stirring step after step s5, alumina particles having a predetermined volume average particle diameter are added to the particle mixture that has been heat-treated in the heat treatment step, and the mixture is stirred using a high-speed mixing device. The volume average particle diameter of the alumina particles used in the post-stirring step is 0.1 μm or more and 3 μm or less, preferably 0.1 μm or more and 1 μm or less, more preferably 0.1 μm or more and 0.5 μm or less. By adding alumina particles having such a predetermined volume average particle diameter, the charge amount of the toner can be increased and fogging can be prevented. When the volume average particle diameter of the alumina particles added in the post-stirring step is less than 0.1 μm or more than 3 μm, the effect of increasing the charge amount of the toner is not sufficient, and the occurrence of fog is sufficiently prevented. Can not.

  Further, the amount of alumina particles added in the post-stirring step is preferably within a range of a mass ratio of 0.05 parts by mass or more and 4 parts by mass or less with respect to 100 parts by mass of the toner particles. If the amount of alumina particles added relative to 100 parts by mass of the toner particles is less than 0.05 parts by mass, the charge amount of the toner cannot be sufficiently increased, and the effect of preventing the occurrence of the photosensitive member fog is not sufficient. Further, when the amount of alumina particles added exceeds 100 parts by mass of toner particles exceeds 4 parts by mass, it adheres to the roller of the toner cartridge to be developed and an image defect occurs, which is not preferable.

  In the post-stirring step, when the alumina particles having a predetermined volume average particle diameter are added to the particle mixture heat-treated in the heat-treating step and mixed and stirred using a high-speed mixing device, the temperature of the mixing and stirring tank ( In the state where the chiller temperature of the high speed mixing device is set to 25 ° C. or lower and the peripheral speed of the tip of the stirring blade of the high speed mixing device is set to 1800 to 3000 m / min, the time during which the alumina particles can be uniformly mixed is 1 minute It is preferable to carry out mixing and stirring within the range of 10 minutes or less and preferably within the range of 1 minute or more and 3 minutes or less. Under such conditions, the particle mixture heat-treated in the heat treatment step and the alumina particles are mixed and stirred to include toner particles (coated particles) having silica particles coated on the surface, and alumina particles. Toner can be obtained.

  As described above, the toner is manufactured through the first stirring step, the second stirring step, the heat treatment step, and the post-stirring step, thereby providing sufficient fluidity and covering the exposed portion of the release agent on the toner particle surface. Therefore, it is possible to produce a non-magnetic one-component negatively chargeable toner that prevents the occurrence of fog and the occurrence of adhesion or sticking of the release agent to the charging blade or the photoreceptor.

(Example)
EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following description.

[Measuring method]
The circularity of the toner particles and the volume average particle diameter of the toner used in the following examples and comparative examples were measured as follows.

<Circularity of toner particles>
The circularity distribution of toner particles was measured using FPIA-3000 manufactured by Sysmex Corporation. Then, in the circularity distribution of the measured toner particles, the circularity C10 when the integrated value of the number frequency from the low circularity is 10%, and the circular shape when the integrated value of the number frequency from the low circularity is 50%. The degree C50 was calculated.

<Volume average particle diameter of toner>
The volume average particle diameter of the toner was measured using a particle size distribution measuring device (trade name: MULTISIZER II, manufactured by Beckman Coulter) with an aperture tube having a diameter of 100 μm.

[Production of non-magnetic one-component negatively chargeable toner]
<Generation of toner particles>
10 parts by mass of a commercially available polyester resin for non-magnetic color toner (trade name: HP-325, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) as a binder and 5 parts by mass of a magenta colorant (Pigment Red 57: 1) as a colorant After being melt-mixed with a pressure kneader, the mixture was melt-kneaded with a hot roll, and the resulting kneaded product was cooled and solidified, and then roughly crushed to obtain a master batch. 15 parts by mass of the master batch, 10 parts by mass of the polyester resin for non-magnetic color toner described above, 80 parts by mass of polyester resin for non-magnetic toner (trade name: ET2900, manufactured by SK Chemicals), negative charging Zinc alkylsalicylate (trade name: BONTRON E-84, manufactured by Orient Chemical Co., Ltd.) as a neutral charge control agent, and polyethylene (trade name: Sunwax 161-P, Sanyo Chemical Industries, Ltd.) as a release agent 4 parts by mass) were added and mixed, and then kneaded with a hot roll to obtain a kneaded product. The kneaded product was cooled and solidified, and then pulverized and classified to obtain toner particles A (non-magnetic) having a volume average particle diameter of 8 μm.

<Manufacture of toner>
Example 1
In the first stirring step, the non-magnetic toner particles A produced as described above are mixed in a mixing and stirring tank (volume capacity 150 L) of a high-speed mixing device (Henschel mixer, manufactured by Mitsui Mining Co., Ltd.) with respect to 100 parts by mass of , Negatively charged silica fine particles (trade name: R812S, BET specific surface area 220 cm ² / g, manufactured by Nippon Aerosil Co., Ltd.) were added to 1.5 parts by mass, and mixed and stirred for 9 minutes under the following stirring conditions did. At this time, the amount of toner particles A introduced into the mixing and stirring tank was about 75 L (30 kg).
Stirring blade shape: Upper blade ST / Lower blade A0
Peripheral speed of tip of stirring blade: upper blade 2500 m / min, lower blade 2410 m / min
Mixing stirring tank temperature (chiller temperature): 20 ° C

  Next, in the second stirring step, 0.5 parts by mass of the same silica fine particles as used in the first stirring step are added to 100 parts by mass of the toner particles A in the mixing agitation tank of the high-speed mixing device. Then, the mixture was further stirred for 2 minutes under the above stirring conditions to obtain a particle mixture A.

  Next, in the heat treatment step, using a hot air treatment apparatus (trade name: Meteole Inbo MR-10 type, manufactured by Nippon Pneumatic Industry Co., Ltd.) having the configuration shown in FIGS. 2 and 3, the hot air temperature Ta is 350 ° C., hot air The particle mixture A was heat-treated under the conditions of an air volume La of 600 lt / min and a particle mixture supply speed Wf of 80 g / min. At this time, in the circularity distribution of the toner particles A, when the integrated value of the number frequency from the low circularity is 10%, the circularity C10 is 0.930, and the integrated value of the number frequency from the low circularity is 50%. The degree of circularity C50 was 0.980.

  Next, in the post-stirring step, alumina particles having a volume average particle diameter of 0.3 μm are 0.5 parts by mass in 100 parts by mass of the heat-treated toner particles A in the mixing / stirring tank of the high-speed mixing device. The toner is mixed and stirred for 2 minutes under the above stirring conditions, and includes the toner particles A having silica fine particles coated on the surface thereof and alumina particles. Toner toner was obtained.

(Examples 2 and 3)
Nonmagnetic one-component negatively chargeable toners of Examples 2 and 3 were obtained in the same manner as in Example 1 except that the addition amount of silica fine particles in the first stirring step was changed to the values shown in Table 1, respectively.

(Examples 4 and 5)
Nonmagnetic one-component negatively chargeable toners of Examples 4 and 5 were obtained in the same manner as in Example 1 except that the amount of silica fine particles added in the second stirring step was changed to the values shown in Table 1, respectively.

(Examples 6 and 7)
Nonmagnetic one-component negatively chargeable toners of Examples 6 and 7 were obtained in the same manner as in Example 1 except that the mixing stirring time in the first stirring step was changed to the values shown in Table 1, respectively.

(Examples 8 and 9)
Nonmagnetic one-component negatively chargeable toners of Examples 8 and 9 were obtained in the same manner as in Example 1 except that the mixing stirring time in the second stirring step was changed to the values shown in Table 1, respectively.

(Example 10)
Example 10 is the same as Example 1 except that the type of silica fine particles used in the first stirring process and the second stirring process is changed to R974 (BET specific surface area 170 cm ² / g) manufactured by Nippon Aerosil Co., Ltd. A non-magnetic one-component negatively chargeable toner was obtained.

(Example 11)
A nonmagnetic one-component negatively chargeable toner of Example 11 was obtained in the same manner as in Example 1 except that the heat treatment conditions in the heat treatment step were changed to the values shown in Table 1, respectively.

Example 12
A nonmagnetic one-component negatively chargeable toner of Example 12 was obtained in the same manner as in Example 1 except that the type of alumina particles used in the post-stirring step was changed to alumina particles having a volume average particle diameter of 0.2 μm. .

(Example 13)
A nonmagnetic one-component negatively chargeable toner of Example 13 was obtained in the same manner as in Example 1 except that the type of alumina particles used in the post-stirring step was changed to alumina particles having a volume average particle diameter of 3 μm.

(Comparative Example 1)
In the first stirring step, the addition amount of the silica fine particles is changed to 2.0 parts by weight with respect to 100 parts by weight of the toner particles A, and the second stirring step is not performed. A nonmagnetic one-component negatively chargeable toner of Comparative Example 1 was obtained.

(Comparative Example 2)
A nonmagnetic one-component negatively chargeable toner of Comparative Example 2 was obtained in the same manner as in Example 1 except that the amount of silica fine particles added in the first stirring step was changed to the values shown in Table 1, respectively.

(Comparative Example 3)
A nonmagnetic one-component negatively chargeable toner of Comparative Example 3 was obtained in the same manner as in Example 1 except that the post-stirring step was not performed and alumina particles were not added.

(Comparative Example 4)
A nonmagnetic one-component negatively chargeable toner of Comparative Example 4 was obtained in the same manner as in Example 1 except that the heat treatment conditions in the heat treatment step were changed to the values shown in Table 1, respectively.

[Evaluation]
The nonmagnetic one-component negatively chargeable toners of Examples 1 to 13 and Comparative Examples 1 to 4 obtained as described above were used as commercially available non-magnetic one-component development type color printers (trade name: Color Laser Jet 4700dn, A test image having a pattern in which a plurality of printing portions are uniformly arranged is printed in a developing tank of Hewlett-Packard (HP). Note that commercially available recycled paper was used as the printing paper, and the printing environment was a temperature of about 25 ° C. and a humidity of about 50%.

<Evaluation of initial fogging>
After printing 10 sheets, the fog was observed with a 25 × magnifier and evaluated. The evaluation criteria are as follows.
○: The surface of the photoconductor is observed with a magnifying glass 25 times, and the number of deposits per 9 mm ² is less than 20 ×: The surface of the photoconductor is observed with a magnifying glass 25 times, and the number of deposits per 9 mm ² is 20 More than

<Evaluation of deposits on photoconductor>
After printing 5K sheets (5000 sheets), the amount of deposits generated on the surface of the photoreceptor was visually evaluated. The evaluation criteria are as follows.
○: No deposit at all △: There is a small amount of deposit ×: Many deposits are generated

<Evaluation of deposits on charging blade>
After printing 5K sheets (5000 sheets), the amount of deposits generated on the surface of the charging blade was visually evaluated. The evaluation criteria are as follows.
○: No deposit at all △: There is a small amount of deposit ×: Many deposits are generated

  The above evaluation results are shown in Table 1. Table 1 shows the production conditions of the first stirring step, the second stirring step, the heat treatment step, and the post-stirring step in the production of the toners of the examples and the comparative examples.

  As shown in Table 1, after adding 1 to 3 parts by mass of silica fine particles to 100 parts by mass of toner particles A and mixing and stirring, 0.2 to 1 parts by mass of silica fine particles are added. In addition, mixing and stirring to obtain a particle mixture, heat treatment is performed so that the toner particles contained in the particle mixture have a predetermined circularity, and alumina particles having a volume average particle diameter of 0.1 μm or more and 3 μm or less are further obtained. In addition, the nonmagnetic one-component negatively chargeable toners of Examples 1 to 13 obtained by mixing and stirring prevented the occurrence of fogging and the occurrence of deposits on the charging blade and the photoreceptor. It turns out that it is a toner.

DESCRIPTION OF SYMBOLS 1 Hot-air processing apparatus 11 Hot-air processing tank 12 Hot-air injection nozzle 13 Raw material injection nozzle 14 Heat insulation mechanism 15 Collision member 16 Air injection means 17 Hopper part

Claims (3)

A binder, a colorant, a release agent, and a negatively chargeable charge control agent are contained, and 1 to 3 parts by mass of silica fine particles are added to 100 parts by mass of toner particles formed by pulverization and mixed and stirred. A first stirring step for obtaining coated particles which are toner particles coated with silica fine particles on the surface;
A second stirring step of adding 0.2 to 1 part by weight of silica fine particles to 100 parts by weight of the toner particles and mixing and stirring to obtain a particle mixture of the coated particles and silica fine particles;
In the circularity distribution of the toner particles contained in the particle mixture obtained in the second stirring step, the circularity when the integrated value of the number frequency from the low circularity is 10% is 0.925 or more, and the low circularity A heat treatment step of heat treating the particle mixture so that the circularity when the integrated value of the number frequency from 50 degrees is 50% is 0.97 or more;
A non-magnetic one-component negative charging comprising: a post-stirring step of adding alumina particles having a volume average particle size of 0.1 to 3 μm to the particle mixture heat-treated in the heat-treating step, followed by mixing and stirring. For producing a functional toner. In the heat treatment step,
An air inlet for taking in cooling air in the upper part, and a hot air treatment tank in which the particle mixture and hot air are supplied from the upper part to the internal space;
A hot air injection nozzle for injecting hot air from the upper part of the hot air treatment tank toward the internal space;
A raw material injection nozzle for injecting the particle mixture toward the hot air injected from the hot air injection nozzle, wherein the lower end opening where the raw material outlet from which the particle mixture is injected is formed is injected with hot air from the hot air injection nozzle. A raw material injection nozzle provided on the inner side of the lower end opening where the hot air outlet is formed, and located above the lower end opening of the hot air injection nozzle;
A heat insulating mechanism that is provided so as to be separated from the raw material injection nozzle and surround the raw material injection nozzle, and includes a cooling jacket in which a flow path through which the refrigerant flows is formed, and insulates the raw material injection nozzle and the hot air injection nozzle; ,
A collision member provided below the lower end opening of the raw material injection nozzle and spaced from the raw material injection nozzle;
Dispersed from the opening at the lower end of the air injection flow path formed by the outer surface portion of the material injection nozzle and the inner surface portion of the cooling jacket of the heat insulation mechanism toward the surface portion facing the lower end opening of the material injection nozzle of the collision member The method for producing a non-magnetic one-component negatively chargeable toner according to claim 1, wherein the particle mixture is heat-treated using a hot-air treatment device including air jetting means for jetting air for use.   A nonmagnetic one-component negatively chargeable toner produced by the method for producing a nonmagnetic one-component negatively chargeable toner according to claim 1.

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