JP6497141B2 - Method for producing carrier for two-component development - Google Patents

Description

  The present invention relates to a method for producing a carrier for two-component development.

In recent years, in electrophotographic technology, high image quality and environmental sustainability accompanying the advancement of the printing area are required. Conventional methods for producing a resin-coated carrier are roughly classified into a solution coating method and a dry coating method.
Solution coating methods include a method in which a resin dissolved in an organic solvent is spray-dried onto a carrier core, a method in which the carrier core is immersed in a resin dissolved in an organic solvent in a kneader, and the solvent is removed while stirring under heating and reduced pressure. There is.
On the other hand, the dry coating method includes a method of applying a strong shear force and heat after immobilizing the powder coating agent on the core surface with a stirring mixer. For example, Patent Document 1 discloses a method in which a coating layer is formed by stirring and mixing powdered resin particles and a core and applying heat using a high-speed stirring mixer, and then cooling and mixing to obtain a carrier. It is disclosed.
As another method, Patent Document 2 discloses a method of coating with a mechanical impact force by a surface treatment apparatus having a rotor and a liner.
As a method for producing a carrier for an electrostatic charge image two-component developer, a method described in Patent Document 3 is known.
In patent document 4, the manufacturing method of the magnetic carrier which prescribed | regulated the temperature and time in a coating process and a heat processing process is patented.

JP-A-9-160307 JP 63-235959 A JP 2013-88553 A Japanese Patent No. 5197195

  The problem to be solved by the present invention is to provide a method for producing a carrier for two-component development in which the resin coating layer on the surface of the carrier is less peeled and the image quality to be formed is excellent.

The present invention has been solved by the means described in <1> below. It is shown below together with <2> which is a preferred embodiment.
<1> Adhering step of mixing magnetic particles and resin particles to adhere resin particles to the surface of the magnetic particles, a casing having a raw material supply port and a discharge port, the same traveling direction from the raw material supply port to the discharge port A rotating body having a rotating shaft in the direction is provided, and a continuous heat treatment apparatus capable of controlling the temperature for each part of the casing is used, and the raw material is supplied with magnetic particles to which the resin particles obtained by the attaching step are attached. A heating and melting step of forming a resin coating layer by heating the magnetic particles to which the resin particles have adhered while passing between the casing and the rotating body and melting the resin particles while passing between the casing and the rotating body, and the heating A cooling and crushing step for obtaining a magnetic particle having a resin coating layer by performing a cooling treatment and a crushing treatment on the heated and melted product obtained by the melting step, and in the heating and melting step, the continuous type Than the temperature of the inner wall of the feed inlet of the heat treatment apparatus, a method of manufacturing a carrier for two-component developer, characterized in that to lower the temperature of the inner wall of the outlet portion of the heat-melting products,
<2> The method for producing a carrier for two-component development according to <1>, wherein the two inner wall temperatures satisfy the following formulas 1 and 2.
Tg (glass transition temperature of resin particles) + 50 ° C. <inner wall temperature (° C.) ≦ TGA (thermal decomposition start temperature of resin particles)
Inner wall temperature at outlet of heated melt <Inner wall temperature of raw material supply port (° C.) ≦ TGA + 100 ° C. Formula 2

According to the invention described in the above <1>, in the heating and melting step, the carrier temperature is the same as or higher than the inner wall temperature of the outlet portion of the heated and melted product than the inner wall temperature of the raw material supply port of the continuous heat treatment apparatus. There is provided a method for producing a carrier for two-component development in which the resin coating layer on the surface is less peeled and the image quality to be formed is excellent.
According to the invention described in the above <2>, the resin coating layer on the carrier surface is less peeled compared to the case where Formula 1 and / or Formula 2 is not satisfied, the image quality of the formed image is excellent, and the manufacture of the carrier Provided is a method for producing a two-component developing carrier having excellent processing ability.

It is a schematic cross section which shows an example of the continuous-type heat processing apparatus used suitably for the manufacturing method of the carrier for two-component development of this embodiment.

Hereinafter, this embodiment will be described in detail.
In the present embodiment, the description “A to B” represents not only a range between A and B but also a range including A and B at both ends thereof. For example, if “A to B” is a numerical value range, “A or more and B or less” or “B or more and A or less” is represented according to the magnitude of the numerical value.

(Method for producing carrier for two-component development)
The method for producing a carrier for two-component development of this embodiment (hereinafter, also simply referred to as “the method of producing a carrier of this embodiment” or “the method of producing this embodiment”) comprises mixing magnetic particles and resin particles. A rotating body provided with a rotating shaft in the same direction as the direction of travel from the raw material supply port to the discharge port, in the casing having the raw material supply port and the discharge port. Then, using a continuous heat treatment apparatus capable of controlling the temperature for each part of the casing, the magnetic particles to which the resin particles obtained by the adhesion step are attached are introduced from the raw material supply port, and the casing and the rotating body The magnetic particles to which the resin particles are adhered are heated while passing between them to melt the resin particles to form a resin coating layer, and the heat melting obtained by the heat melting step A cooling and pulverizing step for obtaining magnetic particles having a resin coating layer, and in the heating and melting step, heating from the inner wall temperature of the raw material supply port of the continuous heating device It is characterized by lowering the inner wall temperature of the molten product outlet.

In the conventional method, when producing magnetic particles having a resin coating layer using a continuous heat treatment apparatus, the resin particles on the surface of the magnetic particles are not completely adhered at the raw material supply port. When force is applied, the coating layer peels off.
As a result of detailed studies by the present inventors, the resin particle is heated and melted in a short time by making the inner wall temperature of the raw material supply port higher than the inner wall temperature of the discharge port portion as a presumed mechanism, and the resin particle layer By adhering to the magnetic particles, it is considered that there is little peeling of the resin coating layer on the surface of the carrier, and a two-component developing carrier excellent in image quality of the image to be formed can be obtained.

<Adhesion process>
The manufacturing method of the carrier for two-component development of this embodiment includes the adhesion process which mixes a magnetic particle and a resin particle, and adheres a resin particle to the said magnetic particle surface.
The magnetic particles form a carrier core material (core) in the obtained carrier. The resin particles form a resin coating layer that covers the surfaces of the magnetic particles in the obtained carrier.
The magnetic particles having resin particles on the surface formed in the attaching step are preferably such that the resin particles adhere to the magnetic particle surface uniformly to some extent, and more preferably magnetic particles having a resin particle adhesion layer on the surface. preferable.
The amount of the resin particles used in the attaching step is preferably 0.5 to 20% by mass, more preferably 1 to 10% by mass, and 2 to 7% by mass with respect to the mass of the magnetic particles. More preferably it is.
Further, for the purpose of mixing with the resin coating layer of the obtained carrier or adhering to the surface of the magnetic particles, in the adhering step, the magnetic particles and the resin particles together with the conductive particles, the charge control agent, the wax, and the coupling agent are used. You may mix well-known additives, such as.
Further, the order of mixing the magnetic particles, the resin particles, and these additives in the adhesion step is not particularly limited, and if desired, all materials may be mixed at one time. The removed coating resin may be mixed and the mixture may be added to the magnetic particles and mixed, or a plurality of coating resins may be divided and mixed.

As a device for mixing the magnetic particles and the resin particles used in the adhesion step, a known powder mixing device can be used, but it is possible to prevent excessive heat and mechanical impact force from being applied. In order to suppress reaggregation of conductive particles and aggregation and fusion of magnetic particles, it is preferable to use a device with a jacket.
The mixing device may be a batch type or a continuous type, and if it is a batch type, a mixing device with a stirrer such as a Henschel mixer or a Nauter mixer is preferably used. In this case, after mixing, the coated product is once discharged into the hopper, and from there, it is supplied to a subsequent continuous heat treatment apparatus by a quantitative feeder.
If it is a continuous type, a single screw type or a twin screw type paddle mixer, a ribbon mixer, an extrusion mixer, etc. are mentioned. The obtained magnetic particles having a resin particle adhesion layer on the surface are once discharged into a hopper, and may be supplied to a subsequent continuous heating device by a quantitative feeder, or directly without using a hopper. You may supply to a continuous heating apparatus. Further, the continuous mixing apparatus may be integrated with the subsequent continuous heating apparatus, or may be integrated with the subsequent cooling and crushing apparatus.
The temperature of the mixture at the time of mixing is preferably Tg-100 ° C. ≦ temperature of the mixture ≦ Tg + 50 ° C. with respect to the glass transition temperature (Tg) of the resin particles, and Tg−50 ° C. ≦ temperature of the mixture ≦ Tg + 20 ° C. It is more preferable that Tg−20 ° C. ≦ temperature of the mixture ≦ Tg + 10 ° C.

[Magnetic particles]
The magnetic particles used in the adhesion step are not particularly limited, and magnetic metals such as iron, nickel, cobalt, and alloys of these magnetic metals with manganese, chromium, rare earth elements (for example, nickel-iron alloys, cobalt-iron). Alloys, aluminum-iron alloys, etc.), magnetic oxides such as ferrite and magnetite used alone in the core, magnetic particles such as magnetite dispersed in the resin, and magnetic materials such as ferrite as binders And a polymer core that is polymerized while dispersing a magnetic material such as magnetite in a monomer.
Negative charge control agents include trimethylethane dyes, metal complexes of salicylic acid, metal complexes of benzylic acid, copper phthalocyanine, perylene, quinacridone, azo pigments, metal complex azo dyes, azochrome complexes, etc. Examples thereof include resins containing at least one of dyes, calixarene type phenolic condensates, cyclic polysaccharides, carboxyl groups and sulfonyl groups.
The content of the negative charge control agent is preferably in the range of 0.001% by mass to 1.0% by mass with respect to the mass of the magnetic particles, and is 0.01% by mass to 0.8% by mass. More preferably, it is the range. When the amount is in the above range, a sufficient effect on the toner charge rising property can be obtained, and the chargeability of the carrier itself is excellent.

As a volume average particle diameter of a magnetic particle, 10-60 micrometers is preferable and 20-50 micrometers is more preferable.
The method for measuring the volume average particle diameter of the magnetic particles is not particularly limited, and may be measured by a known method. For example, a laser diffraction / scattering particle size distribution analyzer (LS Particle Size Analyzer: LS13 320, BECKMAN COULTER) (Beckman Coulter, Inc.) is preferable. The obtained particle size distribution is divided into particle size ranges (channels), and the volume cumulative distribution is subtracted from the small particle size side to _{obtain a} volume average particle size D _50v .

[Resin particles]
The resin particles used in the attaching step are not particularly limited, and known resin particles may be used.
Specific examples of the resin of the resin particles include styrenes such as styrene, chlorostyrene, and methylstyrene; methyl methacrylate, methyl acrylate, propyl methacrylate, propyl acrylate, lauryl acrylate, cyclohexyl methacrylate, cyclohexyl acrylate, methacrylic acid, acrylic acid, Α-methylene aliphatic monocarboxylic acids such as butyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate and ethyl methacrylate; nitrogen-containing acrylics such as dimethylaminoethyl methacrylate; nitriles such as acrylonitrile and methacrylonitrile; 2-vinylpyridine, Vinylpyridines such as 4-vinylpyridine; vinyl ethers; vinyl ketones; olefins such as ethylene, propylene, and butadiene Homopolymers or copolymers such as polyamides, polyimides, melamine and other main chain nitrogen-containing resins; silicone resins such as methylsilicone resins and methylphenylsilicone resins; polyesters obtained by polycondensation of bisphenol, glycol, etc. And the like. Among them, an acrylic resin is preferably exemplified, and a homopolymer of methyl acrylate, methyl methacrylate, propyl acrylate, propyl methacrylate, cyclohexyl acrylate or cyclohexyl methacrylate or a copolymer obtained by copolymerizing at least these monomers is particularly preferred.
The volume average particle diameter of the resin particles used in the adhesion step is preferably 0.01 to 1 μm, preferably 0.05 to 0.5 μm, from the viewpoint of uniform adhesion to the surface of the magnetic particles, dispersibility of the conductive particles, and the like. Is more preferable.
The glass transition temperature (Tg) of the resin particles is not particularly limited, but is preferably 50 ° C to 150 ° C, more preferably 70 ° C to 120 ° C, and 80 ° C to 120 ° C. Is more preferable.
The thermal decomposition start temperature (TGA) of the resin particles is not particularly limited, but is preferably 120 ° C to 300 ° C, more preferably 150 ° C to 300 ° C, and 200 ° C to 300 ° C. Particularly preferred.

[Conductive particles]
The conductive particles used in the present embodiment are not particularly limited as long as the particles exhibit conductivity, but specifically, metals such as carbon black, various metal powders, titanium oxide, tin oxide, magnetite, and ferrite. An oxide etc. are mentioned. Carbon black is particularly preferred because high conductivity can be imparted with a small amount of addition, and the degree of conductivity can be easily controlled by the blending amount.
These conductive particles preferably have a volume primary particle diameter of 0.01 to 0.5 μm. When the volume primary particle diameter is in this range, the mixing / dispersibility with the resin particles is good and the dispersibility in the coating layer is good.
As addition amount of electroconductive particle, the addition amount less than 20 volume% of the resin coating layer or the resin particle to be used is preferable. Moreover, when adding 20 volume% or more, dispersion | distribution control of the powder in a resin coating layer becomes difficult, and control of an electrical resistance may become difficult.

[Other additives]
In the adhesion step, a negative charge control agent may be added. That is, the resin coating layer of the carrier obtained by the production method of the present embodiment may contain a negative charge control agent. Negative charge control agents include trimethylethane dyes, metal complexes of salicylic acid, metal complexes of benzylic acid, copper phthalocyanine, perylene, quinacridone, azo pigments, metal complex azo dyes, azochrome complexes, etc. Examples include dyes, calixarene type phenolic condensates, cyclic polysaccharides, resins containing at least one of carboxyl groups and sulfonyl groups.
The content of the negative charge control agent is preferably in the range of 0.001% by mass to 1.0% by mass with respect to the mass of the magnetic particles, and is 0.01% by mass to 0.8% by mass. More preferably, it is the range. When the amount is in the above range, a sufficient effect on the toner charge rising property can be obtained, and the chargeability of the carrier itself is excellent.

In the adhesion step, a negative charge control agent may be added. That is, the resin coating layer of the carrier obtained by the manufacturing method of the present embodiment may contain wax.
Waxes are usually hydrophobic, are relatively soft at room temperature, and have low film strength. This originates from the molecular structure of the wax, but due to this property, if wax is present in the resin coating layer, particles called external additives added to the toner surface, or toner components such as toner bulk components are transferred to the carrier surface. It is hard to adhere to. Even if it adheres, the surface of the carrier is renewed by peeling off the wax at the adhesion level at the molecular level, and the carrier surface is not easily contaminated.
The wax used in the present embodiment is not particularly limited. For example, paraffin wax and derivatives thereof, montan wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof Derivatives and the like. Derivatives include oxides, polymers with vinyl monomers, and graft modified products. In addition, alcohol, fatty acid, plant wax, animal wax, mineral wax, ester wax, acid amide, and the like may be used. Moreover, you may use another well-known thing.
The melting point of the wax is preferably 60 ° C. or higher and 200 ° C. or lower, and more preferably 80 ° C. or higher and 150 ° C. or lower. Within the above range, the carrier fluidity is excellent.

Moreover, in order to improve the adhesiveness between the magnetic particle surface and the resin coating layer, the magnetic particle surface may be subjected to a coupling treatment.
Examples of coupling agents include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These may be used individually by 1 type and may use 2 or more types together. Among these, a silane coupling agent is preferable.
As the silane coupling agent, any type of chlorosilane, alkoxysilane, silazane, and special silylating agent may be used. Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, Methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N-bis (Trimethylsilyl) urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxy Silane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercapto Examples include propyltrimethoxysilane, γ-chloropropyltrimethoxysilane, and γ-aminopropyltriethoxysilane.
Examples of titanate coupling agents include “Plenact KR TTS”, “Plenact KR 46B”, “Plenact KR 55”, “Plenact KR 41B”, “Plenact KR 38S”, “Plenact KR 138S”, “Preneact K”. 238S "," Plenact 338X "," Plenact KR 44 "," Plenact KR 9SA "," Plenact KR ET "(all of which are manufactured by Ajinomoto Fine Techno Co., Ltd.) and the like, Examples thereof include alkyl acetoacetate aluminum diisopropylate (“Plenact AL-M” manufactured by Ajinomoto Fine Techno Co., Ltd.).

<Heating and melting process>
The two-component developing carrier manufacturing method of the present embodiment includes a rotating body in which a rotating shaft is provided in a casing having a raw material supply port and a discharge port in the same direction as the traveling direction from the raw material supply port to the discharge port. Then, using a continuous heat treatment apparatus capable of controlling the temperature for each part of the casing, the magnetic particles to which the resin particles obtained by the adhesion step are attached are introduced from the raw material supply port, and the casing and the rotating body Including a heating and melting step of heating the magnetic particles to which the resin particles adhere while melting the resin particles to form a resin coating layer, and from the inner wall temperature of the raw material supply port of the continuous heat treatment apparatus , Lower the inner wall temperature of the outlet of the heated and melted product.

Each part of the apparatus used in the heating and melting step will be described below.
The continuous heat treatment apparatus has a casing having a raw material supply port and a discharge port, and a rotating shaft is provided in the casing in the same direction as the raw material traveling direction from the raw material supply port toward the discharge port. A rotating body is provided, and temperature control is possible for each part of the casing.
The position of the raw material supply port and the discharge port in the casing is not particularly limited as long as the raw material charged into the apparatus passes between the inner wall of the casing and the rotating body and can perform the coating forming step. However, it is preferable to have the raw material supply port near one end of the rotating body and the discharge port near the other end of the rotating body.
Further, the continuous heat treatment apparatus has a heating means capable of temperature control for each part of the casing, and further has a cooling means for cooling a part of the casing for the temperature control. It may be.

Moreover, it is preferable that the casing in the continuous heat treatment apparatus has a jacket structure as the heating means and the cooling means. By having the said jacket structure, the temperature adjustment of heating and cooling is easy by a site | part. Moreover, it is preferable that the said jacket structure is provided in the outer side of the said casing, a rotary body main body, or both.
Moreover, it is preferable that the said continuous-type heat processing apparatus has a 1 axis | shaft or biaxial rotating body in the said casing.
The rotating body may control the stirring shear force as desired. For example, the shape of the rotating body and the stirring speed are changed depending on the part of the rotating body, the shape of the casing side is changed without changing the rotating body, or the stirring by the rotating body is performed by the clearance between the rotating body and the casing. Shear force is easily controlled.
Specific examples of the continuous heat treatment apparatus used in the present embodiment include, for example, a paddle mixer, a screw mixer, a turbulizer, a continuous kneader, a twin-screw extrusion kneader and the like provided with heating and cooling means. It is not limited to these. Among these, a twin-screw extrusion kneader provided with heating and cooling means is preferable.

What is necessary is just to select the input speed to the said continuous-type heat processing apparatus of the magnetic particle to which the resin particle adhered in the said heat-melting process is below the feeding capability of a heat processing apparatus. When the charging speed is equal to or less than the feeding capability of the apparatus, the occurrence of clogging is suppressed, and the driving system of the apparatus is not overloaded, and continuous operation is easy. Preferably, the charging speed may be selected so that the filling rate of the processed material within the clearance between the rotating body and the casing of the heating device is 50% to 100% with respect to the feeding capability of the heating device. The higher the filling rate, the better the heat transfer efficiency and the higher the processing capacity.
Moreover, the charging method of the mixed product may be performed intermittently or continuously, but it is preferable to supply the mixed product while maintaining the temperature of the mixed product in the adhesion step. This is to increase the processing capacity of the heating and melting step, and further, the temperature of the mixture may be preheated. Specifically, for example, a heat insulating material is wound around a hopper, or a jacketed hopper is heated with a heat medium.

In the heating and melting step, it is important to perform the heating and melting process continuously.
In the heating and melting step, the magnetic particles to which the charged resin particles are adhered are heated by the heating means while being stirred by the rotating body, and the adhered resin particles are melted to form a resin coating layer on the surface of the magnetic particles. The
Further, in the heating and melting step, passing the magnetic particles having a resin particle adhesion layer between the inner wall of the casing and the rotating body rotates the rotating body to cause the magnetic particles having a resin particle adhesion layer to be passed. This is done by stirring.

In the heating and melting step, the inner wall temperature of the discharge port portion of the heated and melted product is set to be lower than the inner wall temperature of the raw material supply port of the continuous heat treatment apparatus.
In the present embodiment, the outlet of the heated and melted product is the vicinity of the outlet including the outlet of the heated and melted product in the casing (in many cases, including agglomerated magnetic particles having a resin coating layer). It refers to a casing portion, and is preferably a casing portion including a discharge port having a length of 1/10 or more of the entire length of the casing in the direction of the rotation axis of the rotating body. That is, the length of the casing part (low temperature part) including the discharge port whose inner wall temperature is lower than the inner wall temperature of the raw material supply port is 1/10 of the entire length of the casing in the rotation axis direction of the rotating body. It is preferable that it is the above length.
Moreover, it is more preferable that the length of the low temperature part is 1/8 or more of the length of the entire casing in the rotation axis direction of the rotating body, and is 1/4 or more. More preferably.

In the heating and melting step, it is preferable that the inner wall temperature of the discharge port portion of the heated and melted product satisfies the following formula 1. If it is the said aspect, sufficient thickness of the resin coating layer is obtained, and peeling of the resin coating layer is further suppressed.
Tg (glass transition temperature of resin particles) + 50 ° C. <inner wall temperature of outlet of heated melt product ≦ TGA (thermal decomposition start temperature of resin particles) Equation 1
Moreover, in the heating and melting step, it is preferable that the inner wall temperature of the raw material supply port and the inner wall temperature of the discharge port portion of the heated and melted product satisfy the following formula 2. In the above embodiment, peeling of the resin coating layer is further suppressed, and the carrier manufacturing ability is excellent.
Inner wall temperature at outlet of heated melt <Inner wall temperature of raw material supply port (° C.) ≦ TGA + 100 ° C. Formula 2

Further, the inner wall temperature of the outlet portion of the heat-melted product is preferably (Tg + 50 ° C.) to the thermal decomposition start temperature of the resin particles, more preferably (Tg + 80 ° C.) to the thermal decomposition start temperature of the resin particles. . By setting the inner wall temperature of the raw material supply port to the above temperature, the resin particles are heated and melted in a short time and the detailed mechanism is unknown, but the adhesion between the resin coating layer and the magnetic particles is excellent, and the resin coating layer It is estimated that peeling is more suppressed.
Moreover, the inner wall temperature of the discharge port portion of the heat-melted product is preferably equal to or lower than the thermal decomposition start temperature of the resin particles, more preferably equal to or lower than the thermal decomposition start temperature of the resin particles, and 150 ° C to 270 ° C. It is more preferable that the resin particle thermal decomposition start temperature or lower and 180 ° C. to 260 ° C., and the resin particle thermal decomposition start temperature or lower and 200 ° C. to 250 ° C. be still more preferable.
The inner wall temperature of the raw material supply port is preferably 200 ° C to 400 ° C, more preferably 250 ° C to 370 ° C, still more preferably 280 ° C to 360 ° C, and 300 ° C to 350 ° C. It is particularly preferred.

In the heating and melting step, the inner wall temperature of the casing may change stepwise or continuously from the raw material supply port to the discharge port. In the heating and melting step, it is preferable that the inner wall temperature of the casing has the highest inner wall temperature of the raw material supply port and the lowest inner wall temperature of the discharge port in accordance with the rotation axis direction of the rotating body.
Further, in the heating and melting step, it is preferable that the inner wall temperature of the entire casing changes in 2 to 4 stages.

  The thickness of the resin coating layer of the carrier produced in the production method of the present embodiment is preferably in the range of 0.1 μm to 5 μm, and more preferably in the range of 0.2 μm to 3 μm. Within the above range, it is easy to form a uniform and flat resin coating layer on the surface of the magnetic particles, and aggregation of carriers is suppressed.

<Cooling and crushing process>
The manufacturing method of the carrier for two-component development of the present embodiment includes a cooling and crushing step of obtaining a magnetic particle having a resin coating layer by performing a cooling treatment and a crushing treatment on the heat-melted product obtained by the heating and melting step. Including.
In the heat-melting step, the heat-melted product discharged from the discharge port (also referred to as a heat-melted product in this embodiment) forms an aggregate of the particles, so that it is simply at room temperature (for example, When it is allowed to cool in an atmosphere of 5 ° C. to 35 ° C., it solidifies in an aggregated state. Therefore, a step of crushing to primary particles is necessary.
In the cooling and pulverizing step, pulverization is performed by cooling and stirring to obtain magnetic particles having a resin coating layer.
In the cooling and crushing step, the crushing process may be performed simultaneously with the cooling process, continuously performed after the cooling process, or may be cooled after the crushing process. The crushing treatment prior to the cooling treatment is preferred from the viewpoint of suppressing the peeling of the resin coating layer since the particles are not solidified.
There is no restriction | limiting in particular as a cooling means and crushing means used for the said cooling crushing process, A well-known method is used. Further, the cooling in the cooling and crushing step may be performed by simply leaving it at room temperature (for example, in an atmosphere of 5 ° C. to 35 ° C.) without actively cooling.
The cooling treatment in the cooling and crushing step may be a batch type or a continuous type, and if it is a batch type, a mixing device with a stirrer such as a Henschel mixer with a jacket cooling mechanism or a Nauter mixer is preferably used. As long as it is a continuous type, a single-screw or twin-screw paddle mixer with a jetting cooling mechanism, a ribbon mixer, an extrusion mixer, and the like can be given.
The crushing treatment in the cooling crushing step may be either a batch type or a continuous type, and if it is a batch type, a high-speed stirring mixing device such as a Henschel mixer is preferably used. If it is a continuous type, a pin mill, an extrusion type mixer, etc. are mentioned.
The apparatus used for the cooling and crushing step may have a cooling apparatus and a crushing apparatus separately, may be an integrated apparatus that performs cooling and crushing at the same time, or the continuous heating apparatus and the cooling apparatus or An integrated type with a crushing device or a cooling crushing device may be used.

The manufacturing method of this embodiment may include other known steps as necessary.
In addition, the production method of the present embodiment includes a classification step of classifying magnetic particles having the obtained resin coating layer and / or the obtained resin coating layer after the cooling and pulverization step, if necessary. A sieving step of sieving the magnetic particles having may be included.
The classification means and sieve used in the classification step and the sieving step are not particularly limited, and known ones may be used as desired.

An example of a continuous heat treatment apparatus suitably used in the method for producing a two-component development carrier of this embodiment will be described below with reference to the drawings.
In the continuous heat treatment apparatus 10 shown in FIG. 1, magnetic particles to which resin particles adhere from a particle supply apparatus 12 are introduced into a casing 14 through a raw material supply port 16. The continuous heat treatment apparatus 10 is a twin screw extrusion kneader. The magnetic particles to which the charged resin particles are adhered pass between the casing 14 and the rotating body 18 by the rotation of the rotating body 18, pass through the heat treatment units A to D, and from the discharge port 20 to the resin coating layer. It is discharged as a heated and melted product 22 containing an agglomerate of magnetic particles having a particle size. In addition, the particles are also crushed by the rotation of the rotating body 18. Note that the rotating body 18 shown in FIG. 1 is a rotating body having a helical screw shape as a whole.
A jacket (not shown) capable of partially adjusting the temperature is wound around the outer peripheral portion of the casing 14 in the heat treatment units A to D as a heating unit and a cooling unit. The temperature of the heat treatment units A to D is adjusted by the jacket. Further, the heat treatment units A to D in the continuous heat treatment 10 are continuously provided, and the heat treatment unit D (heated melt product discharge port portion) is determined from the inner wall temperature of the heat treatment unit A (raw material supply port portion). ) The inner wall temperature is low.
Further, the inner wall temperature _T A through T _D of the heat treatment unit A~D preferably satisfies Equation 3 and Equation 4 below.
T _A > T _D ... Formula 3
T _A ≧ T _B ≧ T _C ≧ T _D ... Formula 4
In the continuous heat treatment apparatus 10 shown in FIG. 1, the heat treatment unit adjusts the temperature by dividing into four parts A to D, but is not limited to this, and the temperature is set in multiple stages according to the casing length. Adjustment is possible.

(Two-component developer)
The two-component developer of this embodiment is a two-component developer containing a carrier produced by the method for producing a carrier for two-component development of this embodiment and a toner.
In addition, the two-component developer of this embodiment is preferably an electrostatic charge image developer.
The toner used in the exemplary embodiment is not particularly limited, and a known toner is used, and an electrostatic charge image developing toner is preferably used.
The mixing ratio of the toner and the carrier in the two-component developer of this embodiment is not particularly limited and may be appropriately selected depending on the intended purpose. The mixing ratio (mass ratio) of the toner and the carrier is : Carrier = 1: 100 to 30: 100 is preferable, and 3: 100 to 20: 100 is more preferable.
Further, the two-component developing carrier of the present embodiment is a carrier manufactured by the two-component developing carrier manufacturing method of the present embodiment.

(Cartridge, image forming method and image forming apparatus)
The cartridge of this embodiment is a cartridge that contains at least the two-component developer of this embodiment. In addition, it is preferable that the cartridge of this embodiment is detachable from the image forming apparatus.
When used in a developing device, an image forming method, or an image forming apparatus, it may be a toner cartridge that contains toner alone, or a developer cartridge that contains the two-component developer of this embodiment, Further, the process cartridge may include at least developing means for developing the electrostatic latent image formed on the image holding member with the electrostatic charge image two-component developer of the present embodiment to form a toner image.
In addition, the process cartridge according to the present embodiment may include other members such as a charge removing unit as necessary.

The image forming method of the present embodiment is not particularly limited except that the two-component developer of the present embodiment is used as a developer, but the latent image forming step of forming an electrostatic latent image on the surface of the image carrier, A developing step of developing the electrostatic latent image formed on the surface of the image carrier with a developer containing toner to form a toner image, and transferring the toner image formed on the surface of the image carrier to the surface of the transfer target The developer including a transfer step and a fixing step of fixing the toner image transferred to the surface of the transfer target is preferably the two-component developer of the present embodiment.
As an image forming method of the present embodiment, the two-component developer of the present embodiment is prepared, and an electrostatic image is formed and developed using a conventional electrophotographic copying machine, and the obtained toner image is transferred. The image is electrostatically transferred onto paper and fixed by a heat fixing device to form a copy image.

Each of the steps in the image forming method is a general step per se, and is described in, for example, JP-A-56-40868 and JP-A-49-91231. Note that the image forming method of the present embodiment can be carried out by using a known image forming apparatus such as a copying machine or a facsimile machine.
The electrostatic latent image forming step is a step of forming an electrostatic latent image on an image carrier (photoconductor).
The developing step is a step of developing the electrostatic latent image with a developer layer on a developer holding member to form a toner image. The developer layer is not particularly limited as long as it contains the two-component developer of this embodiment.
The transfer step is a step of transferring the toner image onto a transfer target. Examples of the transfer medium in the transfer process include an intermediate transfer medium and a recording medium such as paper.
In the fixing step, for example, there is a method of forming a copy image by fixing the toner image transferred onto the transfer paper by a heating roller fixing device in which the temperature of the heating roller is set to a constant temperature.
The cleaning step is a step of removing the two-component developer remaining on the image carrier.
As the recording medium, known media can be used, for example, paper used for electrophotographic copying machines, printers, OHP sheets, etc. For example, the surface of plain paper is made of resin, etc. Coated coated paper, art paper for printing, and the like can be suitably used.

  The image forming method of the present embodiment may further include a recycling step. The recycling process is a process of transferring the toner collected in the cleaning process to the developer layer. The image forming method including the recycling process is performed using an image forming apparatus such as a toner recycling system type copying machine or facsimile machine. Further, the present invention may be applied to a recycling system in which the cleaning process is omitted and toner is collected simultaneously with development.

The image forming apparatus of the present embodiment is not particularly limited except that it contains the two-component developer of the present embodiment as a developer, but an image carrier, a charging unit that charges the image carrier, and the charged image. An exposure unit that exposes the holding member to form an electrostatic latent image on the image holding member; a developing unit that develops the electrostatic latent image with a developer containing toner to form a toner image; and the toner image. It is preferable that the developer including the toner includes the two-component developer according to the exemplary embodiment.
The image forming apparatus of the present embodiment is not particularly limited as long as it includes at least the image carrier, the charging unit, the exposure unit, the developing unit, and the transfer unit as described above. If necessary, the image forming apparatus may include a fixing unit, a cleaning unit, a static elimination unit, and the like.
In the transfer unit, the transfer may be performed twice or more using an intermediate transfer member. Examples of the transfer medium in the transfer unit include an intermediate transfer medium and a recording medium such as paper.

  The image carrier and each of the above-described units can preferably use the configurations described in the respective steps of the image forming method. As each of the above-described means, a known means in the image forming apparatus can be used. In addition, the image forming apparatus according to the present embodiment may include means and devices other than the above-described configuration. Further, the image forming apparatus according to the present embodiment may simultaneously perform a plurality of the above-described means.

  Hereinafter, although an Example and a comparative example are given and this embodiment is described in detail in detail, this embodiment is not limited to the following examples. Further, the average particle diameter represents a volume average particle diameter unless otherwise specified.

<Fabrication of ferrite particles (magnetic particles)>
After mixing 74 parts by mass of Fe ₂ CO ₃ , 25 parts by mass of MnO _{2 and} 1 part by mass of ZnO, mixing and pulverizing with a wet ball mill for 25 hours, granulating and drying by spray drying, and then using a rotary kiln at 800 ° C., 7 Temporary calcination 1 was performed. This was pulverized with a wet ball mill for 2 hours, further granulated and dried with a spray dryer, and then pre-baked 2 at 1,150 ° C. for 6 hours using a rotary kiln. The calcined product thus obtained was pulverized with a wet ball mill for 5 hours, further granulated and dried again with a spray dryer, and then subjected to main firing at a temperature of 1,150 ° C. for 12 hours using an electric furnace. The main calcination was performed in an atmosphere adjusted so that the oxygen ratio in the mixed gas of nitrogen and oxygen was 12% by volume. And the ferrite particle of the volume average particle diameter of 37 micrometers was produced through the crushing process and the classification process.

<Synthesis of resin particles-1>
-Cyclohexyl methacrylate: 100 parts-Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen SC, solid content concentration: 10% by mass): 6.1 parts Was gradually added. After white turbidity, the temperature was raised to 80 ° C. at 5 ° C./min while purging with nitrogen, and when the temperature reached 80 ° C., the mixture was left for 15 minutes with stirring. An aqueous solution in which 1.0 part of ammonium persulfate (polymerization initiator) was dissolved in 50 parts of ion-exchanged water was added over 30 minutes, and the mixture was allowed to stand for 7 hours after the addition.
Thereafter, the mixture was cooled and freeze-dried at 40 ° C. for 12 hours to obtain resin particles CHMA (A1).
(Average particle size 0.3 μm, glass transition temperature (Tg) 100 ° C., thermal decomposition temperature (TGA) 250 ° C.)

<Synthesis of resin particles-2>
-Methyl methacrylate: 100 parts-Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen SC, solid content concentration: 10% by mass): 6.1 parts Resin particle PMMA (A2) was obtained.
(Average particle size 0.4 μm, glass transition temperature (Tg) 123 ° C., thermal decomposition temperature (TGA) 280 ° C.)

  The glass transition temperature of the resin was determined by a DSC (Differential Scanning Calorimeter) measurement method, and was determined from the main maximum peak measured in accordance with ASTM D3418-8. For the measurement of the main maximum peak, DSC-7 manufactured by PerkinElmer is used. The temperature correction of the detection part of this apparatus uses the melting point of indium and zinc, and the correction of heat quantity uses the heat of fusion of indium. As the sample, an aluminum pan was used, an empty pan was set as a control, and the measurement was performed at a heating rate of 10 ° C./min. The TGA of the resin was calculated by measuring the weight loss in a nitrogen atmosphere using a thermal decomposition apparatus (gas decomposition thermal decomposition apparatus TGA-50 manufactured by Shimadzu Corporation).

(Examples 1-6 and Comparative Examples 1-3)
<Preparation of carrier for two-component development>
Ferrite particles (average particle size 37 μm): 100 parts by mass Resin particles A1: 2.0 parts by mass Carbon black (VXC72, manufactured by Cabot Corporation, average particle size 0.20 μm): 0.02 parts by mass

First, 102.2 parts by mass of the raw material was charged into a Henschel mixer (manufactured by Nippon Coke Industries Co., Ltd.) and stirred and mixed at 2,400 rpm × 10 minutes to produce resin particle-attached magnetic particles.
Using the continuous heat treatment apparatus 10 (continuous biaxial extrusion kneader TEM50, manufactured by Toshiba Machine Co., Ltd.) shown in FIG. Continuous supply was performed at a supply rate (processing capacity), and the temperature of each part A to D of the casing 14 of the continuous heat treatment apparatus 10 was set to the temperature shown in Table 1, and the heated and melted product was recovered from the discharge port 20. The screw rotation speed was set such that the filling rate in the casing was 50 to 100% according to the supply speed.
The recovered heated and melted product is continuously supplied to a comil pulverizer (punching metal φ1 mm), cooled while pulverizing to primary particles, and Examples 1 to 4 and Comparative Examples 1 to 3 having a pulverized product temperature of 70 ° C. or less. Two-component developing carriers were obtained.
In Example 5, the two-component developing carrier of Example 5 was obtained in the same manner as in Example 2 except that resin particle A1: 2.0 parts by mass was changed to resin particle A1: 3.0 parts by mass. It was.
In Example 6, the carrier for two-component development of Example 6 was obtained in the same manner as in Example 2 except that resin particle A1: 2.0 parts by mass was changed to resin particle A2: 2.0 parts by mass. It was.

<Production of developer>
10 parts of toner (manufactured by Fuji Xerox Co., Ltd., toner for Apeos Port C6500) and 100 parts of the carrier obtained in Examples 1 to 6 or Comparative Examples 1 to 3 were stirred with a V blender at 40 rpm × 20 minutes, The two-component developers of Examples 1 to 6 and Comparative Examples 1 to 3 were obtained by sieving with a sieve having an opening of 212 μm.

(Evaluation)
<75 μm net amount>
The produced carrier was subjected to sieving using a sieving mesh having a 75 μm mesh, and the amount of the resin coating layer (coating amount) and the coverage of the resin coating layer were evaluated as substitute characteristics of the carrier alone.

<Amount of coating resin layer (coating amount)>
The weight change of the carrier before and after the removal treatment was measured by dissolving and removing the resin coating layer of the carrier with a solvent in which the resin particles are soluble.

<Coating ratio of resin coating layer>
It was determined by XPS measurement (X-ray photoelectron spectroscopy measurement). As an XPS measurement device, JPS80 manufactured by JEOL Ltd. was used, and measurement was performed using an MgKα ray as an X-ray source, setting an acceleration voltage to 10 kV, and an emission current to 20 mV. The main element (carbon) constituting and the main elements (iron and oxygen) constituting the magnetic particle were measured.

<Evaluation of actual machine>
Using each of the two-component developers obtained in Examples 1 to 6 or Comparative Examples 1 to 3, an image with an image density of 10% was output using an ApeosPort C6500 manufactured by Fuji Xerox Co., Ltd. The following evaluation was conducted. The results are shown in Table 1.

<< Observation of carrier surface (evaluation of peeling of resin coating layer) >>
Toner was blown off from each developer before output and after output of 100,000 images, and surface observation by SEM was performed. The surface of the carrier was observed using a FE-SEM (S4100 manufactured by Hitachi, Ltd.) at a magnification of × 3,000. The evaluation criteria are as follows.
○: There is no peeling of the resin coating layer, and there is little or no exposure of the magnetic particles. Δ: There is peeling of the resin coating layer and a part of the exposure of the magnetic particles. X: There is clear peeling of the resin coating layer.

<< Image quality change: white spots due to carrier skip (image quality maintenance evaluation) >>
Count the number of carriers flying in the solid image part of the A3 image output to the 100,000th sheet. If the number of carriers is 3 or less, ○ if 4 or more, 9 or less, Δ, 10 or more The case of was evaluated as x.

In Examples 1 to 6, the coating was made uniform, and the resin coating layer was not peeled off and the magnetic particles were hardly exposed even after outputting 100,000 sheets of images.
In Comparative Examples 1 and 2, the coating state before output was good, but peeling of the resin coating layer was conspicuous in the carrier after outputting 100,000 images. This is presumably because the heat at the time of heating was not sufficiently transmitted and peeled off over time due to the poor adhesion between the magnetic particles and the resin coating layer.
Comparative Example 3 was a heat treatment apparatus, and the amount of the resin coating layer was reduced. This is presumably because the resin particles were burned out by thermal decomposition because the magnetic particles were higher than the TGA of the resin particles.
Further, in Examples 1 to 6 using the two-component developing carrier of the present embodiment that can obtain a good coating even over time, it was shown that the carrier has high image quality maintenance.
When the cause of white spots due to carrier jump was confirmed, it was found that the carrier resistance was lowered due to the exposure of the magnetic particles, and the carrier was developed in the image area.
In Comparative Example 3, since the magnetic particles were exposed much more than before output, the image quality maintenance evaluation was not performed.

  10: Continuous heat treatment device, 12: Particle supply device, 14: Casing, 16: Raw material supply port, 18: Rotating body, 20: Discharge port, 22: Heated melt, AD: Heat treatment unit

Claims (1)

An adhering step of adhering the resin particles to the surface of the magnetic particles by mixing magnetic particles and resin particles;
A casing having a raw material supply port and a discharge port is provided with a rotating body provided with a rotating shaft in the same direction as the traveling direction from the raw material supply port to the discharge port, and is capable of temperature control for each part of the casing. Using a heat treatment apparatus, the magnetic particles to which the resin particles obtained in the attaching step are attached are introduced from the raw material supply port and passed between the casing and the rotating body, and the magnetic particles to which the resin particles are attached. Heating and melting step of melting the resin particles to form a resin coating layer, and
A cooling and crushing step of performing a cooling treatment and a crushing treatment on the heat-melted product obtained by the heating and melting step to obtain magnetic particles having a resin coating layer,
In the heating and melting step, the inner wall temperature of the discharge port portion of the heated and melted product is made lower than the inner wall temperature of the raw material supply port of the continuous heat treatment apparatus ,
The two inner wall temperatures satisfy the following formulas 1 and 2,
The method for producing a carrier for two-component development, wherein an inner wall temperature of the raw material supply port is 280 ° C to 360 ° C.
Tg (glass transition temperature of resin particles) + 50 ° C. <inner wall temperature (° C.) ≦ TGA (thermal decomposition start temperature of resin particles)
Inner wall temperature (° C.) of discharge port of heated melt product <Inner wall temperature of raw material supply port (° C.) ≦ TGA + 100 ° C. Formula 2

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