JP5361558B2 - Magnetic carrier manufacturing method and magnetic carrier manufactured using the manufacturing method - Google Patents

Description

  The present invention relates to a magnetic carrier used in a developing method for developing a latent image formed on an electrostatic latent image carrier with a two-component developer to form a toner image on the electrostatic latent image carrier. And a magnetic carrier using the manufacturing method.

  In recent years, two-component developers used in electrophotography have been renewed in terms of performance in order to meet market needs such as an accelerated color shift for office use, high definition for the graphics market, and high speed for light printing. High image quality and high stability are required.

  At present, the magnetic carrier constituting the two-component developer has a coating layer formed of resin composition particles on the surfaces of ferrite core particles and magnetic material dispersed resin core particles (hereinafter referred to as magnetic carrier core particles). Career is mainstream.

  The coating layer suppresses the injection of charges from the magnetic carrier to the photoreceptor in order to stabilize the toner charge amount distribution and to improve the durability that can be stably charged even after long-term use. Playing a role.

  Conventionally, as a method for coating the surface of the magnetic carrier core particles with the resin composition particles, a coating solution obtained by dissolving the resin composition particles in a solvent is sprayed on the surface of the magnetic carrier core particles floating in a fluidized bed. Many methods are based on a so-called wet coating process such as a coating method or a coating process in which the magnetic carrier core particles are immersed in a coating solution obtained by dissolving the resin composition particles in a solvent.

  The wet coating method described above is effective in that the resin composition particles are uniformly coated on the surfaces of the magnetic carrier core particles. However, the wet coating treatment has a problem that the magnetic carriers are easily coalesced when the solvent volatilizes.

  Once the magnetic carrier that has been coalesced is crushed by stirring, the surface of the magnetic carrier core particle is exposed on the crushed surface, and the so-called leakage phenomenon, which is the phenomenon of charge injection from the magnetic carrier to the photoconductor described above. Is likely to occur.

  When the above-described leakage phenomenon occurs, the surface potential of the photosensitive member converges on the developing bias, and development contrast cannot be ensured, and a whiteout image may occur. In addition, since the surface of the magnetic carrier core particles is exposed, it becomes impossible to retain the charge of the toner, particularly under high temperature and high humidity, and image defects such as fog are likely to occur due to the low charge of the toner after being left for a long time. .

  Furthermore, in order to completely remove the solvent, a separate drying step is required, which causes a tact-up factor, and there are still many improvements regarding the wet coating treatment from the viewpoint of production.

  Therefore, as a method for overcoming the problems of the wet coating process, a method of performing a dry coating process with heat has been proposed.

  For example, using a high-speed stirrer / mixer, a powdery processed product is mixed and stirred with a stirring blade, and thermally coated at a temperature equal to or higher than the glass transition point (Tg) of the resin composition particles contained in the processed product. A method for obtaining a magnetic carrier is disclosed (Patent Document 1). In the above method, a separate drying step is not necessary.

  However, since the entire apparatus is heated by flowing a heat medium through a jacket installed inside the main body casing, the temperature of the entire processed product becomes equal to or higher than the glass transition point (Tg) of the resin composition particles contained in the processed product. However, unification of magnetic carriers is likely to occur, and it is still insufficient in that uniform coating treatment is performed.

  On the other hand, a method of performing a dry coating process by a mechanical impact force has been proposed. For example, a method of coating the resin composition particles having a particle size of 1/10 or less of the magnetic carrier core particles on the surface of the magnetic carrier core particles using a surface modification treatment apparatus having a rotor and a stator Is disclosed (Patent Document 2).

  In the above-described method, the resin composition particles are dispersed on the surface of the magnetic carrier core particles using an apparatus different from the apparatus for coating treatment, and there is an inconvenience that a separate apparatus for dispersion is required. is there. When the dispersion apparatus is not used, the resin composition particles remain free and it is difficult to satisfactorily coat the resin composition particles on the surfaces of the magnetic carrier core particles.

  In addition, even if the resin composition particles are attached to the surface of the magnetic carrier core particles using an apparatus different from the apparatus for coating, an excessive amount of the resin composition particles is not added. Since the resin composition particles (hereinafter referred to as residual resin composition particles) are in a free state, it is difficult to perform uniform coating.

  Therefore, in the above-described method, the coating amount of the resin composition particles is limited, and it may be difficult to control the charge amount of the toner and to suppress the injection of charges from the magnetic carrier to the photoconductor.

  On the other hand, in order to increase the coating amount of the resin composition particles, a method of intermittently supplying the resin composition particles at least twice using a high-speed stirring mixer is disclosed ( Patent Document 3).

  However, even in the method described above, uncoated residual resin composition particles are generated, and every time a magnetic carrier is produced, performance variation occurs between the magnetic carriers, such as the chargeability and specific resistance of the magnetic carrier. There are cases where a stable magnetic carrier cannot be obtained.

  In addition, as a composite processing device using mechanical impact force, while taking advantage of the rotary blade type device, by applying unprecedented strong force to the processed material such as powder, the stirring effect is enhanced. A treatment apparatus capable of performing various treatments such as compounding of treated products and surface modification has been proposed (Patent Document 4).

  In the apparatus described above, it is possible to coat the resin composition particles on the surface of the magnetic carrier core particles by a dry process. However, there is still a problem in the uniformity of the coating treatment of the resin composition particles, particularly in the uniformity of the surface of the magnetic carrier.

  In addition, depending on the resin composition particle type, there is a problem that uncoated residual resin composition particles are generated, and examination is still insufficient in terms of stabilizing the formulation by reducing the residual resin composition particles. In the present invention, the uniform coating treatment of the resin composition particles means that there is no layer thickness unevenness on the surface of the magnetic carrier after the coating treatment, and there is no particle interface.

JP 09-160307 A JP 63-235959 A Japanese Patent No. 2811079 JP 2005-270955 A

  An object of the present invention is to provide a production method for uniformly coating the surface of the magnetic carrier core particles with the resin composition particles by a dry coating process.

  A further object of the present invention is to uniformly coat the resin composition particles on the surface of the magnetic carrier core particles, to suppress the occurrence of cracking and chipping of the magnetic carrier core particles, and to form a coating layer of the resin composition particles. The object is to provide a magnetic carrier having no unevenness in thickness and no particle interface.

  Furthermore, the object of the present invention is to obtain a magnetic carrier with excellent temporal stability that can stabilize the formulation by reducing residual resin composition particles and suppress a decrease in toner charge amount after standing even under high temperature and high humidity. It is.

  Said subject is achieved by the structure of the following this invention.

[1] Mechanical by impact using a coating apparatus having a means for the coating treatment method of the magnetic resistance carrier that have a that the coating process overturn the resin composition particles to the surface of the magnetic carrier core particles Because
The coating apparatus is that Yusuke least a rotating body in which a plurality of agitating member has a surface, a driving unit for rotationally driving the rotation body, a body casing which is provided with a the stirrer拌部material and gap device And
In the coating treatment step, the magnetic carrier core particles and the resin composition particles are rotated in the direction of the drive unit, which is one direction of the axial direction of the rotating body, by rotating the rotating body and using a part of the stirring member. The magnetic carrier core particles and the resin composition particles are fed by the other part of the stirring member in a direction opposite to the driving unit, which is the reverse direction of the axial direction of the rotating body, in the direction of the driving unit. And by repeating the feeding in the direction of the counter-drive portion, the coating treatment of the resin composition is performed on the surfaces of the magnetic carrier core particles,
As the coating treatment, the resin composition particles are added and then the first coating treatment is performed, and then the resin composition particles are further charged and the coating treatment is performed, so that the resin composition particles are charged in a plurality of times. And the manufacturing method of the magnetic carrier characterized by performing the coating process in multiple times.

  [2] After the resin composition particles are charged, a first coating treatment is performed, and the resin composition particles are charged in a plurality of times as the resin composition particles are charged and the coating treatment is performed. When performing the coating treatment a plurality of times, when the amount of the resin composition particles charged first time is A parts by mass and the amount of the resin composition particles charged after the first time is B parts by mass, the magnetic carrier core particles 100. The method for producing a magnetic carrier according to [1], wherein the input amount A of the resin composition particles is 0.1 part by mass or more and 1.0 part by mass or less with respect to 0 part by mass.

[3] The method for producing a magnetic carrier according to [1] or [2], wherein the relationship between the input amount A of the resin composition particles and the input amount B of the resin composition particles satisfies the following formula: .
A <B

  [4] A magnetic carrier obtained by coating the surfaces of the magnetic carrier core particles with the resin composition particles, which is produced by the production method according to any one of [1] to [3].

[5] The magnetic carrier has a circularity distribution of circularity (a) obtained by the following formula, wherein the number of magnetic carrier particles having a circularity (a) of 0.900 or less is 10.0% by number or less. The magnetic carrier according to [4], which is characterized.
Circularity a = L ₀ / L
[L ₀ represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the particle image. ]

  According to the present invention, it is possible to provide a production method in which the resin composition particles are uniformly coated on the surfaces of the magnetic carrier core particles by a dry coating process.

  Furthermore, according to the present invention, the surface of the magnetic carrier core particles is uniformly coated with the resin composition particles, the cracking and chipping of the magnetic carrier core particles are suppressed, and the coating layer of the resin composition particles It is possible to provide a magnetic carrier having uneven thickness and no particle interface on the surface of the magnetic carrier.

  Furthermore, according to the present invention, it is possible to obtain a magnetic carrier excellent in stability over time that can reduce residual resin composition particles and can suppress a decrease in toner charge amount after standing even under high temperature and high humidity.

It is a schematic diagram which shows an example of the coating processing apparatus which can be used for the manufacturing method of the magnetic carrier of this invention. It is a schematic diagram which shows the structure of the stirring member used for the coating processing apparatus which can be used for the manufacturing method of the magnetic carrier of this invention. It is a figure which shows an example of the electron microscope (SEM) of the magnetic carrier surface obtained by the manufacturing method of this invention. It is a figure which shows an example of the electron microscope (SEM) of the magnetic carrier surface obtained by the manufacturing method of a reference example.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  The method for producing a magnetic carrier according to the present invention comprises a coating treatment step of coating the surface of the magnetic carrier core particles with the resin composition particles using a coating treatment apparatus having means for coating with mechanical impact force. Have. First, the coating process of the magnetic carrier of this invention is demonstrated using FIG.1 and FIG.2 (a).

  The magnetic carrier coating process in the present invention includes a rotating body 2 having at least a plurality of stirring members 3 installed on the surface, a drive unit 8 that rotationally drives the rotating body, and a gap between the stirring member 3 and the rotating member 2. The main body casing 1 is provided.

  In the coating process of the magnetic carrier in the present invention, the magnetic carrier core particles and the resin composition which are put into the coating processing apparatus are prepared by rotating the rotating body 2 by the driving unit 8 using the coating processing apparatus. The resin composition particles are coated on the surfaces of the magnetic carrier core particles by stirring and mixing the particles.

  In the present invention, in FIG. 2A, the magnetic carrier core particles and the resin composition introduced into the coating processing apparatus are unidirectional in the axial direction of the rotating body by a part of the stirring member. Is sent in the drive unit direction (12), and is sent in the counter drive unit direction (13), which is the reverse direction of the drive unit direction, by the other part of the stirring member to the drive unit direction. The surface of the magnetic carrier core particles is coated with the resin composition while repeating the feeding (12) and the feeding (13) in the direction of the counter driving portion.

  In the present invention, the resin composition particles are applied a plurality of times, as in the coating treatment, the first coating treatment is performed after the resin composition particles are added, and the resin composition particles are further charged to perform the coating treatment. It is characterized in that it is divided into a plurality of times and the coating process is performed a plurality of times. Hereinafter, the present invention will be described in more detail with reference to the schematic views of the apparatus shown in FIG. 1 and FIG. 2 (a).

  The apparatus shown in FIG. 1 is provided with a rotating body 2 having at least a plurality of stirring members 3 installed on the surface, a drive unit 8 that rotationally drives the rotating body 2, and a gap between the stirring member 3 and the apparatus. It has the main body casing 1 and the jacket 4 which can exist in the inner side of the main body casing 1, and the rotary body end part side surface 10, and can let a cooling medium flow through it.

  Further, in the apparatus shown in FIG. 1, in order to introduce the magnetic carrier core particles and the resin composition particles, the raw material inlet 5 formed in the upper part of the main casing 1 and the coated magnetic carrier are used as the main casing. 1 has a magnetic carrier outlet 6 formed in the lower part of the main casing 1 in order to discharge it to the outside.

  Further, the apparatus shown in FIG. 1 has a magnetic carrier discharge port 6 formed in the lower part of the main body casing 1 in order to discharge the coated magnetic carrier to the outside of the main body casing 1. Further, in the apparatus shown in FIG. 1, a raw material inlet inner piece 16 is inserted into the raw material inlet 5, and a magnetic carrier outlet inner piece 17 is inserted into the magnetic carrier outlet 6. ing.

  In the present invention, first, the raw material inlet inner piece 16 is taken out from the raw material inlet 5, and the magnetic carrier core particles are introduced from the raw material inlet 5. Next, the resin composition is charged from the raw material inlet 5, and the inner piece 16 for raw material inlet is inserted. Next, the rotating body 2 is rotated by the driving unit 8, and the processed material charged as described above is coated while being stirred and mixed by the plurality of stirring members 3 provided on the surface of the rotating body 2.

  The order of charging may be such that the resin composition is first charged from the raw material charging port 5 and then the magnetic carrier core particles are charged from the raw material charging port 5. Further, after the magnetic carrier core particles and the resin composition are mixed in advance by a mixer such as a Henschel mixer, the mixture may be charged from the raw material inlet 5 of the apparatus shown in FIG.

  After the coating process is completed, the inner piece 17 for the magnetic carrier discharge port in the magnetic carrier discharge port 6 is taken out, the rotating body 2 is rotated by the drive unit 8, and the magnetic carrier is discharged from the product discharge port 6. . The obtained magnetic carrier is subjected to magnetic separation, and if necessary, the residual resin composition is separated with a sieve such as a circular vibrating sieve to obtain a magnetic carrier.

  In the present invention, the coating process is performed by the batch method as described above, but the coating process is performed by the continuous method in a state where the raw material inlet inner piece 16 and the magnetic carrier outlet inner piece 17 are taken out from the beginning. You may do.

  When performing the coating process in the continuous mode, the rotor 2 is rotated by the drive unit 8 with the raw material inlet inner piece 16 and the magnetic carrier outlet inner piece 17 taken out from the beginning, A processed product is introduced from the raw material inlet 5 and the magnetic carrier is recovered from the magnetic carrier outlet 6.

  A feature of the present invention is that when the resin composition particles are coated on the surfaces of the magnetic carrier core particles, the apparatus shown in FIG. 1 is used to perform a first coating treatment after the resin composition particles are added. As in the case where the resin composition particles are charged and the coating process is performed, the resin composition particles are charged in a plurality of times and the coating process is performed a plurality of times.

  That is, in the present invention, first, the magnetic carrier core particles are introduced from the raw material introduction port 5. Next, the resin composition particles are charged from the raw material charging port 5, and the magnetic carrier core particles and the resin composition particles thus charged are stirred and mixed by the stirring member 3 provided on the surface of the rotating body 2. The coating process is performed.

  In this case, in FIG. 2A, when the stirring member 3 is located at the upper part of the rotating body 2 as the stirring member 3a, and the stirring member located at the center of the rotating body 2 is used as the stirring member 3b, the stirring member 3a. When a line is drawn in a direction perpendicular to the center of the rotating body 2 from the end position of the rotating member 2, the adjacent stirring member 3a and the stirring member 3b are preferably in a positional relationship such that they overlap by a width d.

  After the coating treatment, the resin composition particles are further introduced from the raw material inlet 5, and the coating treatment is performed while stirring and mixing with a plurality of stirring members 3 provided on the surface of the rotating body 2. This is repeated a plurality of times, and after the coating process is completed, the magnetic carrier is discharged from the magnetic carrier discharge port 6 to obtain a magnetic carrier.

  As a result of the study by the present inventors, the apparatus used for coating the resin composition particles on the surfaces of the magnetic carrier core particles is the apparatus shown in FIG. 1, and the resin composition particles are charged as described above. After performing the first coating treatment, and adding the resin composition particles and performing the coating treatment, the resin composition particles are charged in a plurality of times, and the coating treatment is performed a plurality of times. It has been found that there are almost no residual resin composition particles, and the resin composition particles can be uniformly coated on the surface of the magnetic carrier core particles.

  As the above reason, as shown in FIG. 2A, the rotating body 2 rotates in the counterclockwise direction 11 when viewed from the direction of the driving unit 8 during the covering process. At that time, the stirring member 3b located at the center of the rotating body 2 rotates in a direction to move to the position of the stirring member 3a.

  At this time, the magnetic carrier core particles and the resin composition particles are sent from the rotating body end side surface 10 to the direction of the drive unit 8 (12) by the stirring member 3b, and the stirring blade 3a It is sent from the drive unit 8 in the direction (13) of the end face 10 of the rotating body.

  Further, since the agitating member 3a and the agitating member 3b are in a positional relationship where the agitating member 3b overlaps with the width d, the magnetic force sent from the rotating member end side surface 10 to the direction of the drive unit 8 by the agitating member 3b (12). The carrier core particles and the resin composition particles collide with the magnetic carrier core particles and the resin composition particles sent from the driving unit 8 in the direction (13) of the rotating body end portion side surface 10 by the stirring blade 3a. To do.

  That is, the rotation of the rotating body 2 feeds the rotating body end side surface 10 to the direction of the driving unit 8 (12) and the driving unit 8 moves to the direction of the rotating body end side surface 10 (13). Is repeatedly performed, and the collision of the magnetic carrier core particles and the resin composition particles with the overlapping width d is repeatedly performed, so that the movement path of the processed material in the main body casing 1 is complicated, and Long distance and uniform mixing.

  Furthermore, the first coating treatment is considered to exhibit a smoothing effect on the surface of the magnetic carrier core particles by forming a thin coating layer of the resin composition particles on the surface of the magnetic carrier core particles.

  And, since the residual resin composition particles remaining in the first coating treatment are familiar with the first coating layer by the second and subsequent coating treatments, the resin composition particles are easily taken in, so that the resin composition It is believed that a magnetic carrier can be obtained in which there is no unevenness or particle interface in the thickness of the covering layer of physical particles.

Further, in the present invention, when the resin composition particles are coated on the surfaces of the magnetic carrier core particles, the first coating treatment is performed after the resin composition particles are added, and the resin composition particles are further charged. As the coating treatment is performed, the resin composition particles are charged in a plurality of times, and when the coating treatment is performed a plurality of times, the amount of the resin composition particles to be charged in the first time is A part by mass, When the input amount of the resin composition particles is B parts by mass, the input amount A of the resin composition particles is 0.1 parts by mass or more and 1.0 parts by mass or less with respect to 100.0 parts by mass of the magnetic carrier core particles. Preferably there is. Furthermore, it is preferable that the relationship between the input amount A of the resin composition particles and the input amount B of the resin composition particles satisfies the following formula.
A <B

  As a result of the study by the present inventors, when the resin composition particles are coated on the surface of the magnetic carrier core particles, the resin composition particles are added once and the residual resin composition is simply increased. It has been found that achieving particle reduction can be difficult.

  Further, when the magnetic carrier produced by the above-described method is observed in detail with an electron microscope (SEM), as shown in FIG. 4, there are unevenness and particle interfaces in the thickness of the coating layer of the resin composition particles. I found out. Furthermore, it has been found that when high power is applied to the treated product during the coating treatment, the surface of the magnetic carrier core particles is cracked or chipped.

  As a result of the study by the present inventor to solve the above-described problems, the input amount A of the resin composition particles is different from the input amount A of the resin composition particles. By making the amount of the resin composition particles less than B, as shown in FIG. 3, there is no unevenness and particle interface in the thickness of the coating layer of the resin composition particles, and the surface of the magnetic carrier core particles It has been found that the resin composition particles can be uniformly coated to suppress the occurrence of cracks and chipping of the magnetic carrier core particles.

  The reason for this is that when the resin composition particles are introduced at once, the coating layer thickness of the resin composition particles is uneven, and the particle interface is present during the coating process. This is presumably because the coating treatment is preferentially performed from the concave portions of the concavo-convex portions present on the particle surface, and the convex portion is finally covered.

  Even if the treatment time is increased to cover the convex portions present on the surfaces of the magnetic carrier core particles, the reduction of the residual resin composition particles cannot be achieved. That is, in order to uniformly coat the resin composition particles on the surface of the magnetic carrier core particles, it is important how to eliminate the unevenness present on the surface of the magnetic carrier core particles.

  In the present invention, the concave and convex portions present on the surface of the magnetic carrier core particles are coated at an early stage by the coating treatment with the input amount A of the resin composition particles, so that the concave and convex portions relatively with the convex portions. The difference can be eliminated, and the thin resin composition particle layer can be formed on the surface of the magnetic carrier core particle.

  In the state where the thin resin composition particle layer is present on the surface of the magnetic carrier core particle and the effect of fitting with the coating layer of the input amount B of the resin composition particle is given, the resin composition particle Since the coating amount of B is applied, there is no unevenness in the thickness of the coating layer of the resin composition particles, there is no particle interface, and the formulation can be stabilized by reducing the residual resin composition particles. ing.

  As a result of the study by the present inventors, the input amount A of the resin composition particles is preferably 0.1 parts by mass or more and 1.0 parts by mass or less with respect to 100.0 parts by mass of the magnetic carrier core particles. A more preferable range is 0.2 parts by mass or more and 0.9 parts by mass or less. The number of coating treatments of the resin composition particles may be two or more, but is preferably two from the viewpoint of cost. At this time, the input amount B of the resin composition particles is preferably 5.0 parts by mass or less, and more preferably 4.0 parts by mass or less.

  In the present invention, the magnetic carrier core particles and the resin composition particles are separately charged as a method of charging, but the magnetic carrier core particles and the resin composition particles are mixed in advance by a mixing device such as a mixer. May be added after mixing.

  That is, the magnetic carrier core particles and the resin composition particles are mixed in advance with a mixer or the like, and the mixture is put into the apparatus shown in FIG. 1 to perform a coating treatment. It is also possible to use a method in which material particles are introduced to perform a coating treatment.

  Further, the magnetic carrier core particles and the resin composition particles are previously mixed with a mixer or the like, and the mixed product is put into the apparatus shown in FIG. 1 to perform a coating treatment. The resin composition particles may be once discharged and further mixed with the resin composition particles with a mixer or the like, and the mixed product may be again charged into the apparatus shown in FIG.

Further, in the present invention, the first coating treatment is performed after the resin composition particles are added, and the resin composition particles are further charged and the coating treatment is performed, so that the resin composition particles are charged in a plurality of times. When the coating process is performed, it is preferable to control the temperature T (° C.) in the processing space 9 between the main casing 1 and the stirring member 3 during the coating process to a range satisfying the following formula.
Tg-50 ≦ T ≦ Tg + 20 (° C.)
(Tg: glass transition temperature of the resin composition particle (° C.))

  The glass transition point (Tg) of the coating resin composition particles is preferably 70 ° C. or higher, and more preferably 80 ° C. or higher. Accordingly, the temperature T (° C.) of the treated product during the coating treatment is preferably 20 ° C. or higher, and more preferably 30 ° C. or higher.

  The temperature T (° C.) of the processed product during the coating process is the atmospheric temperature in the main body casing 1 during the coating process. Specifically, this is the maximum temperature during the coating process when a thermocouple is attached to the inner wall surface of the main body casing 1 from the outside of the apparatus and the thermal history during the coating process is measured.

  In the case of the conventional thermal dry coating treatment, the temperature T (° C.) in the vicinity of the treated product during the coating treatment needs to be somewhat higher than the Tg of the resin composition particles. The entire apparatus was heated by flowing a heat medium through the jacket 4 installed inside.

  However, the higher the temperature T (° C.) in the vicinity of the processing object during the coating process, the easier the uneven distribution and retention of the processed object, the unification of the magnetic carriers is promoted, and the uniform coating process cannot be performed. There is a case. On the other hand, if the temperature T (° C.) in the vicinity of the treated product during the coating process is lowered, the adhesion of the resin composition particles to the surface of the magnetic carrier core particles and the coating process itself become insufficient. It has been very difficult to achieve both the suppression of coalescence of magnetic carriers and the uniform coating treatment.

  On the other hand, in the present invention, the first coating treatment is performed after the resin composition particles are added, and the resin composition particles are further charged and the coating treatment is performed, so that the resin composition particles are charged in a plurality of times. Compared with a conventional dry coating processing apparatus that performs coating processing using mechanical impact force by performing coating processing a plurality of times, the resin composition has a temperature T (° C.) in the vicinity of the processed material during the coating processing. By making it lower than the Tg of the particles, a uniform coating treatment became possible.

  For the above reason, in the present invention, the feed from the rotating body end side surface 10 to the direction of the drive unit 8 (12) and the drive unit 8 to the direction of the rotary body end portion side surface 10 (13). In addition to the collision between the inner wall of the main body casing 1 and the stirring member 3 and the processed product, the processed products collide effectively and frequently. As a result, for each of the magnetic carrier particles, heat is instantaneously applied in a very small region, and the temperature of the processed material is Tg or more only locally, and is cooled in a region other than the region to be processed. The temperature drops. For this reason, coalescence of the magnetic carriers can be prevented, and the nonuniformity of the coating layer due to the occurrence of the crushing surface of the coalesced magnetic carrier is eliminated. Then, after the resin composition particles are added, the first coating treatment is performed, and the resin composition particles are further charged and the coating treatment is performed. Therefore, as described above, it is considered that a uniform coating process can be performed by repeatedly raising and lowering the temperature of the processed material.

  Further, after the resin composition particles are added, the first coating treatment is performed, and the resin composition particles are further charged and the coating treatment is performed. As a result, collisions between treated products occur effectively and frequently, and a good coating treatment can be performed without setting the temperature T (° C.) of the treated product during the coating treatment to be higher than the Tg of the resin composition particles. It is believed that the unity of magnetic carriers can be suppressed.

  Therefore, in the present invention, the first coating treatment is performed after the resin composition particles are added, and then the resin composition particles are further charged and the coating treatment is performed. By performing the treatment and controlling the temperature T (° C.) of the treated product during the coating treatment as described above, it is possible to achieve both high levels of suppressing magnetic carrier coalescence and performing a uniform coating treatment. It became so. In order to control the temperature T (° C.) of the processed product during the coating process, it is preferable to use the rotating body 2 or the main body casing 1 having the jacket 4 through which a cooling medium can flow. As the cooling medium, fluids such as cooling chiller water, hot water, steam, and oil can be used.

  Moreover, in this invention, it is preferable that the positional relationship of this stirring member 3 is arrange | positioned as follows.

  In FIG. 2A, when a line is drawn in the vertical direction from the end position of the stirring member 3a, it is preferable that the adjacent stirring member 3a and the stirring member 3b overlap each other by a width d. The overlapping width d is preferably 0.05D to 0.50D, and more preferably 0.10D to 0.30D, where D is the maximum width of the stirring member 3a. Further, the shape of the stirring member 3 may be a paddle shape as shown in FIG.

In the present invention, the treatment time of the treatment is preferably 2 minutes or more and 60 minutes or less when the effective treatment volume of the treatment space 9 is 2.0 × 10 ⁻³ m ³ . At the time of scaling up, the processing time is obtained from the product of the above processing time and the cube root of a multiple of the processing space 9 volume. For example, in an apparatus in which the effective volume of the processing space 9 is 2.0 × 10 ⁻³ m ³ , when the processing time is 10 minutes, the effective volume of the processing space 9 is 4.0 × 10 ⁻² m ³ . When the apparatus is scaled up, the processing time is 10 minutes × 3√20≈27 minutes.

  Further, in the present invention, in the present invention, the power given to the processed material is preferably 45% or more and 85% or less of the rated power of the drive unit 8. For example, if the rating of the drive unit 8 is 5.5 kW, the power applied to the processed material is preferably 2.5 kW or more and 4.7 kW or less, and if the rating of the drive unit 8 is 30.0 kW, the processing The power given to the object is preferably 13.5 kW or more and 25.5 kW or less.

  Moreover, in this invention, it is preferable to control the rotational peripheral speed of this stirring member 3 so that the power given to a process part may be settled in the above-mentioned range. Specifically, it is preferably 5 m / sec or more and 30 m / sec, more preferably 10 m / sec or more and 20 m / sec or less at the outermost end.

  In the present invention, it is preferable to adjust the gap between the main casing 1 and the stirring blade 3 so that the power applied to the processing section is within the above-described range. Specifically, it is preferably 0.5 mm or more and 30.0 mm or less, and more preferably 1.0 mm or more and 20.0 mm or less.

  As described above, the resin composition is controlled by controlling the power applied to the processed material, the peripheral speed of the stirring member 3, the gap between the main casing 1 and the stirring blade 3, the processing time, and the input amount within the above ranges. The product particles can be uniformly coated. Furthermore, there are few residual resin composition particles, there is no cracking or chipping of the magnetic carrier core particles, the surface is smooth, the adhesion strength is strong, and the toner charge amount decrease after standing is suppressed even at high temperature and high quality. It is possible to obtain a magnetic carrier having excellent stability over time.

  The magnetic carrier obtained by the production method of the present invention preferably has a volume-based 50% particle size (D50) in the range of 20.0 μm to 100.0 μm, more preferably 25.0 μm to 60.0 μm. A range is preferable.

  When the volume-based 50% particle size (D50) is in the range of 20.0 μm or more and 100.0 μm or less, the density of the magnetic brush at the developing pole is optimized, and the toner charge amount distribution is sharpened. Image quality can be improved. Further, in order to set the volume-based 50% particle size (D50) of the magnetic carrier to a range of 20.0 μm or more and 100.0 μm or less, the volume-based 50% particle size (D50) of the magnetic carrier core particle is 19 The range is preferably from 5 μm to 99.5 μm, more preferably from 24.5 μm to 59.5 μm.

  In addition, the magnetic carrier obtained by the production method of the present invention preferably has an average circularity of 0.920 or more, more preferably 0.950 or more from the viewpoint of imparting a charge amount to the toner.

Further, in the magnetic carrier obtained by the production method of the present invention, in the volume-based circularity distribution, the number of magnetic carrier particles having a circularity (a) of 0.900 or less in the following formula is 10.0% or less. preferable.
Circularity a = L ₀ / L
[L ₀ represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the particle image. ]

  The magnetic carrier having a circularity of 0.900 or less in the circularity distribution is an irregular particle, particularly a particle generated by cracking, chipping, agglomeration, etc., and generally means a magnetic carrier that has not been uniformly coated. To do.

  In the present invention, it is possible to perform the coating treatment without applying excessive stress to the magnetic carrier by dividing into a plurality of times without treating a large amount of the resin composition particles at one time. The ratio of the magnetic carrier having a circularity of 0.900 or less in the toner can be 10.0% by volume or less, and it is possible to suppress a decrease in the toner charge amount after being left at high temperature and high quality. A magnetic carrier can be obtained.

  Next, the magnetic carrier core particles will be described. As the magnetic carrier core particles, known magnetic carrier core particles such as known ferrite particles, magnetite particles, and magnetic material-dispersed resin carrier cores can be used. The magnetic carrier core particles are produced, for example, as described below.

  The magnetic carrier core particles are produced using a magnetic material. Examples of the magnetic material include magnetic ferrite particles containing at least one element selected from iron, lithium, beryllium, magnesium, calcium, rubidium, strontium, nickel, cobalt, manganese, chromium and titanium, or magnetite particles. It is done.

  Preferred are magnetite particles or ferrite particles having at least one element selected from manganese, calcium, lithium and magnesium.

  Examples of the ferrite particles include Ca—Mg—Fe ferrite, Li—Fe ferrite, Mn—Mg—Fe ferrite, Ca—Be—Fe ferrite, Mn—Mg—Sr—Fe ferrite, Li—Mg—. Examples thereof include iron-based oxide particles such as Fe-based ferrite, Li-Ca-Mg-Fe-based ferrite, and Li-Mn-Fe-based ferrite.

  The ferrite particles of the iron-based oxide can be obtained by mixing metal oxides, carbonates and nitrates in a wet or dry manner and pre-firing to obtain a desired ferrite composition. Next, the obtained iron-based oxide ferrite is pulverized to submicron.

  To the pulverized ferrite, 20% by mass to 50% by mass of water for adjusting the particle size of the magnetic carrier core is added, and for example, polyvinyl alcohol (molecular weight of 500 or more and 10,000 or less) is 0.1 as a binder resin. A slurry is prepared by adding 10% by weight or more and 10% by weight or less. The slurry is granulated using a spray dryer or the like and fired to obtain a ferrite core.

  As another method, a monomer for forming the binder resin of the magnetic material-dispersed resin carrier core can be obtained by polymerizing in the presence of the magnetic material. Examples of the monomer for forming the binder resin include the following.

  Vinyl monomers, bisphenols and epichlorohydrin for forming epoxy resins; phenols and aldehydes for forming phenol resins; ureas and aldehydes, melamine and aldehydes for forming urea resins are included.

  A method of polymerizing a phenol resin from phenols and aldehydes is particularly preferable. In this case, a magnetic substance-dispersed resin carrier core is produced by adding a magnetic substance, phenols and aldehydes to an aqueous medium, and polymerizing the phenols and aldehydes in the aqueous medium in the presence of a basic catalyst. can do.

  The phenols for producing the phenol resin may be compounds having a phenolic hydroxyl group in addition to phenol (hydroxybenzene). Examples of the compound having a phenolic hydroxyl group include alkylphenols such as m-cresol, p-tert-butylphenol, o-propylphenol, resorcinol, and bisphenol A; hydrogen of an aromatic ring (for example, benzene ring) or part of hydrogen of an alkyl group Or, halogenated phenols, all of which are substituted with chlorine atoms or bromine atoms.

  Examples of aldehydes for producing a phenol resin include the following. For example, formalin, formaldehyde in any form of paraformaldehyde, and furfural, more preferably formaldehyde.

  The molar ratio of aldehydes to phenols is preferably 1: 1 to 1: 4, more preferably 1: 1.2 to 1: 3. If the molar ratio of aldehydes to phenols is less than 1, particles are difficult to produce, and even if they are produced, the resin does not easily cure, and the strength of the particles produced tends to be weak. On the other hand, when the molar ratio of aldehydes to phenols is larger than 4, unreacted aldehydes remaining in the aqueous medium after the reaction tend to increase.

  The condensation of phenols with aldehydes can be performed using a basic catalyst. The basic catalyst may be any catalyst used in the production of ordinary resol type resins. Examples of the basic catalyst include aqueous ammonia, hexamethylenetetramine, dimethylamine, diethyltriamine, and alkylamines such as polyethyleneimine. Is included. The molar ratio of these basic catalysts to phenols is preferably 1: 0.02 to 1: 0.3.

  Moreover, examples of the magnetic material used for the magnetic material-dispersed resin carrier core include magnetite particles and ferrite particles, and those having a particle size of 0.02 μm or more and 2.00 μm or less are suitable.

  Specific methods for producing the magnetic material-dispersed resin particles include the following methods. For example, submicron magnetic materials such as iron powder, magnetite particles, and ferrite particles are kneaded so as to be dispersed in a thermoplastic resin, pulverized to a desired carrier particle size, and if necessary, a thermal or mechanical spherical shape It can be obtained by applying a chemical treatment. It is also possible to produce a carrier core by a polymerization method by dispersing a magnetic substance in a monomer and polymerizing the monomer to form a resin.

  Next, the resin composition particles for coating the magnetic carrier core surface used in the present invention will be described. The resin composition particles used in the present invention contain at least a resin component. As the resin component, a thermoplastic resin is preferably used. Moreover, as a resin component, one type of resin may be sufficient and the combination of 2 or more types of resin may be sufficient.

  Examples of thermoplastic resins as the resin component include polystyrene; acrylic resins such as polymethyl methacrylate and styrene-methacrylic acid copolymer; styrene-butadiene copolymer; ethylene-vinyl acetate copolymer; polyvinyl chloride; Polyvinyl acetate; polyvinylidene fluoride resin; fluorocarbon resin; perfluorocarbon resin; solvent-soluble perfluorocarbon resin; polyvinyl alcohol; polyvinyl acetal; polyvinyl pyrrolidone; petroleum resin; cellulose; Cellulose derivatives such as propyl cellulose; novolak resin; low molecular weight polyethylene; saturated alkyl polyester resin, polyethylene terephthalate Polybutylene terephthalate, such as polyarylate polyester resin; include polyether ketone resin; polyamide resin; polyacetal resin; polycarbonate resins; polyether sulfone resins; polysulfone resin; polyphenylene sulfide resin.

  The weight average molecular weight Mw of the tetrahydrofuran (THF) -soluble component of the resin component contained in the resin composition particles is 15,000 or more and 1,000,000 or less, indicating that the adhesion to the magnetic carrier core and the coating This is preferable in that the surface of the magnetic carrier core can be coated uniformly.

  The volume-based 50% particle size (D50) of the resin composition particles is preferably from 0.1 μm to 15.0 μm, and more preferably from 0.1 μm to 5.0 μm. Furthermore, 0.3 to 3.0 μm is preferable.

  Methods for producing the resin composition particles include a method of directly obtaining particles by suspension polymerization, emulsion polymerization or the like, or a method of producing particles while synthesizing particles by solution polymerization and then removing the solution by spray drying or the like. Is mentioned.

  As the toner used together with the magnetic carrier of the present invention, a known toner can be used, and the toner may be produced by any method such as a pulverization method, a polymerization method, an emulsion aggregation method, a dissolution suspension method and the like.

  Next, the constituent material of the toner particles containing the binder resin, wax and colorant according to the present invention will be described. In the present invention, various known toner particle materials can be used.

  As the binder resin constituting the toner particles, a resin usually used for toner can be used. The following are listed.

  In the toner suitably used in the present invention, the binder resin may be polystyrene; a styrene-substituted homopolymer such as poly-p-chlorostyrene or polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene. -Vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer Polymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer Styrenic copolymers such as coalesced; Vinyl chloride, phenol resin, natural modified phenol resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl Examples include butyral, terpene resin, coumarone indene resin and petroleum resin. In the present invention, a crosslinked styrene resin and a crosslinked polyester resin are preferred binder resins for surface modification of the particles.

  Among the physical properties of the toner, those resulting from the binder resin include a region having a molecular weight of 2,000 to 50,000 in the molecular weight distribution measured by gel permeation chromatography (GPC) soluble in tetrahydrofuran (THF). More preferably, a component having at least one peak and having a molecular weight of 1,000 to 30,000 is present in an amount of 50% to 90%.

  In the toner suitably used in the present invention, the following wax is used as the material of the toner particles from the viewpoint of improving the releasability from the fixing member at the time of fixing and improving the fixing property. Examples of the wax include paraffin wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, and carnauba wax and derivatives thereof. Derivatives of these waxes include oxides, block copolymers with vinyl monomers, and graft modified products. Examples of the wax include alcohol, fatty acid, acid amide, ester, ketone, hydrogenated castor oil and derivatives thereof, plant wax, animal wax, mineral wax, and petrolactam.

  In the toner suitably used in the present invention, in order to control the charge amount and charge amount distribution of the toner particles, a charge control agent is blended into the toner particles (internal addition) or mixed with the toner particles (external addition). And preferably used.

  Examples of the negative charge control agent for controlling the toner to be negatively charged include organometallic complexes and chelate compounds. Examples of the organometallic complex include a monoazo metal complex, an acetylacetone metal complex, an aromatic hydroxycarboxylic acid metal complex, and an aromatic dicarboxylic acid metal complex. Further, the negative charge control agent includes aromatic hydroxycarboxylic acid, aromatic monocarboxylic acid and aromatic polycarboxylic acid and metal salts thereof; anhydrous hydroxycarboxylic acid, aromatic monocarboxylic acid and aromatic polycarboxylic acid anhydride. Products; ester compounds of aromatic hydroxycarboxylic acids, aromatic monocarboxylic acids and aromatic polycarboxylic acids, and phenol derivatives such as bisphenol.

  Examples of positive charge control agents for controlling the toner to be positively charged include nigrosine and fatty acid metal salts modified from nigrosine; tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate Quaternary ammonium salts and their lake pigments; phosphonium salts such as tributylbenzylphosphonium-1-hydroxy-4-naphthosulfonate and tetrabutylphosphonium tetrafluoroborate and lake pigments thereof; triphenylmethane dyes and lakes thereof Pigment (Phosphotungstic acid, phosphomolybdic acid, phosphotungstic molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.); metal salt of higher fatty acid; dibutyls Oxide, dioctyltin oxide, such as diorganotin oxide dicyclohexyl tin oxide; dibutyl tin borate, dioctyl tin borate, include such diorgano tin borate dicyclohexyl tin borate.

  These charge control agents can be used alone or in combination of two or more. Moreover, charge control resin can also be used and it can also use together with said charge control agent.

  The above charge control agent is preferably used in the form of fine particles. When these charge control agents are internally added to the toner particles, they are 0.1 parts by mass or more and 20.0 parts by mass or less, particularly 0.2 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the binder resin. Is preferably added to the toner particles.

  In the toner suitably used in the present invention, various conventionally known colorants can be used as the toner particle material. The colorant used in the present invention is combined so that the black colorant is toned in black by a chromatic colorant such as magnetite, carbon black, the following yellow colorant, magenta colorant and cyan colorant. Is used.

  As the yellow colorant, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds are used.

  Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 155, 162, 168, 174, 176, 180, 181, 191.

  As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds are used.

  Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 31, 48; 2, 48; 3, 48; 4, 57; 1, 81; 1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221, 238, 254.

  As the cyan colorant, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds are used. Specifically, C.I. I. Pigment blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66.

  These colorants can be used alone or in combination and further in the form of a solid solution. In the present invention, the colorant is selected in consideration of hue angle, saturation, brightness, weather resistance, OHP transparency, and dispersibility in the toner.

  These chromatic and non-magnetic colorants are contained in the toner particles in a total amount of 1.0 to 20.0 parts by mass with respect to 100 parts by mass of the binder resin. Further, the magnetic colorant is contained in the toner particles in a total amount of 20 to 60 parts by mass with respect to 100 parts by mass of the binder resin.

  In the toner suitably used in the present invention, an external additive which is fine particles may be externally added. By externally adding fine particles, fluidity and transferability can be improved. The external additive externally added to the toner particle surface preferably contains fine particles of any one of titanium oxide, alumina oxide, and silica fine particles.

  The surface of the fine particles contained in the external additive is preferably subjected to a hydrophobic treatment. The hydrophobizing treatment is preferably performed by a coupling agent such as various titanium coupling agents and silane coupling agents; fatty acids and metal salts thereof; silicone oils; or a combination thereof.

  Among various combinations, it is preferable to add fine particles having a number average particle diameter of 80 nm to 300 nm as one of the fine particles. The reason is that the adhesion force with the carrier can be reduced, and even if the toner has a high charge, it can be developed efficiently.

  Examples of the material include silica, alumina, titanium oxide, cerium oxide and the like. In the case of silica, any silica produced by using a conventionally known technique such as a gas phase decomposition method, a combustion method, or a deflagration method can be used. Among these, silica particles obtained by a sol-gel method capable of sharpening the particle size distribution are preferable.

  The content of the external additive in the toner is preferably 0.1% by mass or more and 5.0% by mass or less, and more preferably 0.5% by mass or more and 4.0% by mass or less. The external additive may be a combination of a plurality of types of fine particles.

  When the two-component developer is prepared by mixing the magnetic carrier and toner of the present invention, the mixing ratio is 2% by mass to 15% by mass, preferably 4% by mass to 13% by mass as the toner concentration in the developer. If it is less than%, usually good results are obtained. When the toner concentration is 2% by mass or less, the image density is liable to decrease, and when it exceeds 15% by mass, fogging or in-machine scattering tends to occur.

  Next, a measurement method according to the present invention will be described.

<Measurement of glass transition point (Tg) of resin composition particles>
The glass transition point (Tg) of the resin composition particles is measured according to ASTM D3418-82 using a differential scanning calorimeter “Q1000” (manufactured by TA Instruments). The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of heat uses the heat of fusion of indium.

  Specifically, about 10 mg of resin composition particles are precisely weighed, placed in an aluminum pan, an empty aluminum pan is used as a reference, and a temperature increase rate of 10 is measured within a measurement range of 30 to 200 ° C. Measurement is performed at ° C / min. In this temperature rising process, a specific heat change is obtained in the temperature range of 40 ° C to 100 ° C.

  At this time, the intersection of the base line midpoint and the differential heat curve before and after the specific heat change occurs is defined as the glass transition temperature Tg of the resin composition particles.

<Method for Measuring Content of Magnetic Carrier Core, Resin Composition Particles, and Volume Distribution Reference 50% Particle Size (D50) of Magnetic Carrier, and Particles of 10.0 μm or More in Resin Composition Particles>
For the particle size distribution measurement, the laser diffraction / scattering particle size distribution measuring device “Microtrack MT3300EX” (manufactured by Nikkiso Co., Ltd.) is equipped with a sample feeder “One-shot dry type conditioner Turbotrac” (manufactured by Nikkiso Co., Ltd.) for dry measurement. And measure.

  As the supply conditions of Turbotrac, a dust collector is used as a vacuum source, the air volume is 33 liters / sec, the pressure is 17 kPa, and control is automatically performed on software. For the particle diameter, a 50% particle diameter (D50), which is a cumulative value based on volume, is obtained, and the content of particles of 10.0 μm or more is obtained. Control and analysis are performed using attached software (version 10.3.3-202D).

  The measurement conditions were SetZero time 10 seconds, measurement time 10 seconds, and one measurement. The particle refractive index is 1.81, the particle shape is non-spherical, the measurement upper limit is 1408 μm, and the measurement lower limit is 0.243 μm. The measurement is performed in a normal temperature and normal humidity (23 ° C., 50% RH) environment.

<Molecular weight measurement of resin composition particles>
The molecular weight distribution of the tetrahydrofuran (THF) soluble content of the resin composition particles is measured by gel permeation chromatography (GPC) as follows.

  First, the resin composition particles are dissolved in tetrahydrofuran (THF) at 23 ° C. for 24 hours. The obtained solution is filtered through a solvent-resistant membrane filter “Maescho Disc” (manufactured by Tosoh Corporation) having a pore diameter of 0.2 μm to obtain a sample solution.

The sample solution is adjusted so that the concentration of the component soluble in THF is 0.8% by mass. Using this sample solution, measurement is performed under the following conditions.
Apparatus: HLC8120 GPC (detector: RI) (manufactured by Tosoh Corporation)
Column: Shodex KF-801, 802, 803, 804, 805, 806,
7 series of 807 (made by Showa Denko)
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 ml / min
Oven temperature: 40.0 ° C
Sample injection volume: 0.10 ml

  In calculating the molecular weight of the sample, standard polystyrene resin (for example, trade name “TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F— 10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500 ", manufactured by Tosoh Corporation) are used.

<Measurement of Average Circularity of Magnetic Carrier Core, Average Circularity of Magnetic Carrier, and Ratio of Magnetic Carrier with Circularity of 0.900 or Less>
The average circularity of the magnetic carrier core and the magnetic carrier, and the ratio of the magnetic carrier having a circularity of 0.900 or less are measured using the flow type particle image analyzer “FPIA-3000 type” (manufactured by Sysmex Corporation) as follows. Measure under conditions.

  In the measurement, automatic focus adjustment is performed using standard latex particles (for example, Duke Scientific 5200A diluted with ion-exchanged water) before the measurement is started. After completion of automatic focus adjustment, a dispersion for measurement is prepared.

  Specifically, an appropriate amount of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 20 ml of ion-exchanged water in a beaker, and then 0.3 g of a measurement sample is added.

  Next, a dispersion process is performed for 2 minutes using a tabletop ultrasonic cleaner / disperser (eg, “VS-150” (manufactured by Vervo Creer)) having an oscillation frequency of 50 kHz and an electric output of 150 W. A dispersion is obtained.

  The average circularity of the magnetic carrier core and the average circularity of the magnetic carrier were measured using the above flow type particle image analyzer equipped with a standard objective lens (10 times), and the dispersion prepared according to the above procedure was used in the above flow. This is calculated by measuring 500 magnetic carrier cores and magnetic carriers in the total count mode in the HPF measurement mode.

  At that time, as a measurement condition, the binarization threshold at the time of particle analysis is 85%, the equivalent circle diameter is based on the number, the particle size limitation is 19.92 μm to 200.00 μm, and the shape limitation is 0.20 to 1.00. The average circularity of the magnetic carrier core and the average circularity of the magnetic carrier are obtained.

  The ratio of the magnetic carrier having a circularity of 0.900 or less was also measured using the above-mentioned flow-type particle image analyzer equipped with a standard objective lens (10 times), and the dispersion liquid prepared according to the above procedure was used as the flow-type particle image. It introduce | transduces into an analyzer and calculates | requires by measuring 500 magnetic carriers in a total count mode by HPF measurement mode.

  As measurement conditions, the binarization threshold at the time of particle analysis is 85%, the equivalent circle diameter is based on the number, the particle size limitation is 19.92 μm to 200.00 μm, and the shape limitation is 0.200 to 0.900. The magnetic carrier is measured, and the number of particles having a circularity of 0.900 or less is determined.

  Next, the number of particles whose circular equivalent diameter is based on the number, the particle size limitation is 19.92 μm or more and 200.00 μm or less, the shape limitation is 0.200 or more and 1.000 or less, and the circularity of the magnetic carrier is 1.000 or less. Ask for.

  By dividing the number of particles having a circularity of 0.900 or less of the magnetic carrier by the number of particles having an average circularity of 1.000 or less of the magnetic carrier, the ratio of the magnetic carrier having a circularity of 0.900 or less is obtained.

<Measurement of Residual Resin Composition Particles in Magnetic Carrier>
The residual resin composition particles in the magnetic carrier are also measured by using the above flow type particle image analyzer equipped with a standard objective lens (10 times), and the dispersion liquid prepared according to the above procedure is used as the above flow type particle image analyzer. And obtained by measuring 500 magnetic carriers in the total count mode in the HPF measurement mode.

  At that time, as the measurement conditions, the binarization threshold at the time of particle analysis is 85%, the equivalent circle diameter is based on volume, the particle size limitation is 0.500 μm to 19.92 μm, and the shape limitation is 0.200 to 1.000. The magnetic carrier is measured to determine the abundance of particles present within the particle size limit, and this is measured as residual resin composition particles.

  Hereinafter, the present invention will be described in more detail with reference to specific production examples and examples, but the present invention is not limited thereto.

<Example of manufacturing magnetic carrier core a>
Magnetite particles (number average particle size 0.3 μm) and a silane coupling agent (3- (2-aminoethylaminopropyl) trimethoxysilane) are introduced into a container. At this time, the silane coupling agent was introduced in an amount of 3.0% by mass with respect to the mass of the magnetite particles. In the vessel, the magnetite particles were surface-treated by high-speed mixing and stirring at 110 ° C.

Next, the magnetic carrier core a was manufactured using the material shown below.
Phenol: 10.0 parts by mass Formaldehyde solution (37% by mass aqueous solution): 6.0 parts by mass Surface-treated magnetite particles: 84.0 parts by mass The above materials, 5 parts by mass of 28% by mass ammonia water, and 25 parts by mass of water Was heated to 85 ° C. over 30 minutes while mixing, and allowed to cure by polymerization for 3 hours. Then, after cooling to 30 degreeC and adding water, the supernatant liquid was removed, the precipitate was washed with water, and then air-dried.

  Subsequently, this was dried under reduced pressure at a temperature of 60 ° C. to obtain a magnetic carrier core a of a magnetic fine particle dispersed type in which magnetite particles were dispersed in a phenol resin.

  The obtained magnetic carrier core a has a volume-based 50% particle size (D50) of 37.2 μm, an average circularity of 0.970, and a ratio of the magnetic carrier core having a circularity of 0.900 or less of 4. It was 0% by number. The results are shown in Table 1.

<Example of production of magnetic carrier core b>
The magnetic carrier core b was manufactured using the material shown below.
Fe ₂ O ₃ : 66.5 parts by mass MnCO ₃ : 28.1 parts by mass Mg (OH) ₂ : 4.8 parts by mass SrCO ₃ : 0.6 parts by mass The calcined ferrite composition was pulverized with a ball mill for 2 hours. The number average particle diameter of the obtained pulverized product was 0.8 μm. Water (300 parts by mass with respect to the pulverized product) and polyvinyl alcohol having a weight average molecular weight of 5,000 (3 parts by mass with respect to the pulverized product) were added to the obtained pulverized product, and granulated with a spray dryer.

  Next, the granulated product was sintered in an electric furnace in a nitrogen atmosphere having an oxygen concentration of 2.0% at 1300 ° C. for 6 hours, and then pulverized and further classified to obtain a Mn—Mg—Sr—Fe ferrite composition. A magnetic carrier core b was obtained.

  The volume-based 50% particle size (D50) of the obtained magnetic carrier core b is 42.3 μm, the average circularity is 0.950, and the ratio of the magnetic carrier core having a circularity of 0.900 or less is 6. It was 0% by number. The results are shown in Table 1.

<Production example of resin composition particle α>
In a four-necked separable flask equipped with a stirrer, a condenser, a thermometer, and a nitrogen introduction tube, 100.0 parts by mass of methanol and 200.0 parts by mass of methyl ethyl ketone were charged as solvents. Furthermore, 400.0 parts by mass of methyl methacrylate monomer, 100.0 parts by mass of cyclohexyl methacrylate monomer, and 3.0 parts by mass of azobisisovaleronitrile as a polymerization initiator were added, and the conditions were 65 ° C. with stirring and introduction of nitrogen. Under the condition, a solution polymerization reaction was carried out for 12 hours to obtain a polymerization solution.

  Into a four-necked separable flask equipped with a stirrer, a Liebig condenser, and a thermometer, 500 parts by mass of hexane-exchanged water is added, and 100.0 parts by mass of the above polymerized solution is added to the flask, and the mixture is stirred at 95 ° C. for 10 hours. Solvent removal was performed with heating and stirring. The obtained resin dispersion was separated by filtration to obtain a resin component. The resin component was dried at 50 ° C. until the resin content was 99.5% or more to obtain a resin.

  The obtained resin is coarsely pulverized with a coarse pulverizer, and further finely pulverized with a fine pulverizer. The volume-based 50% particle size (D50) is 8.1 μm, 10.1 μm or more is 17.8% by volume. Resin composition particles α were obtained. The obtained resin composition particles α had a weight average molecular weight Mw of 51000 and a glass transition point (Tg) of 98.0 ° C. The results are shown in Table 2.

<Production Example of Resin Composition Particle β>
5.0 parts by mass of carbon black having an average primary particle size of 20.0 nm is added to 100.0 parts by mass of the resin described above, mixed using a Henschel mixer, and melt-kneaded with a twin-screw extruder. did. The obtained kneaded product was cooled and coarsely pulverized to 1.0 mm or less with a coarse pulverizer to obtain a coarsely pulverized product.

  The obtained coarsely pulverized product was finely pulverized using a fine pulverizer and then classified by an air classifier to obtain resin composition particles β. The obtained resin composition particles β had a volume-based 50% particle size (D50) of 3.7 μm, and 10.1 μm or more was 4.2% by volume. The results are shown in Table 2.

<Example of toner production>
A toner was manufactured using the following materials and manufacturing method.

Polyester resin (peak molecular weight Mp6500, Tg65 ° C.): 100.0 parts by mass I. Pigment Blue 15: 3: 5.0 parts by mass Paraffin wax (melting point: 75 ° C.): 5.0 parts by mass 3,5-di-t-butylsalicylic acid aluminum compound: 0.5 parts by mass The above materials are mixed with a Henschel mixer. After that, the mixture was melt kneaded with a twin screw extruder. The obtained kneaded product was cooled and coarsely pulverized to 1 mm or less with a coarse pulverizer to obtain a coarsely pulverized product. The resulting coarsely pulverized product was finely pulverized using a pulverizer and then classified by an air classifier to obtain toner particles. The volume-based 50% particle size (D50) of the obtained toner particles was 6.5 μm.

The following materials were added to 100.0 parts by mass of the obtained toner particles, and externally added using a Henschel mixer to produce a toner.
Anatase type titanium oxide fine powder: 1.0 part by mass (BET specific surface area 80 m ² / g, treated with 12% by mass of isobutyltrimethoxysilane)
Oil-treated silica: 1.5 parts by mass (BET specific surface area 95 m ² / g, silicone oil 15% by mass treatment)
Spherical silica: 1.5 parts by mass (hexamethyldisilazane treatment, BET specific surface area 24 m ² / g, number average particle size: 0.1 μm)

[Example 1]
Coating was performed using the apparatus shown in FIG. 1, and a magnetic carrier was manufactured using the materials and manufacturing methods shown below.

In the present embodiment, the apparatus shown in FIG. 1 has a processing space 9 having a volume of 2.0 × 10 ⁻³ m ³ , the rated power of the drive unit 8 is set to 5.5 kW, and the stirring member 3 is used. The shape of was made the thing of Fig.2 (a). 2A, the overlapping width d of the stirring member 3a and the stirring member 3b is set to 0.25D with respect to the maximum width D of the stirring member 3, and the inner periphery of the stirring member 3 and the main body casing 1 is set. And the minimum gap was 3.0 mm.

  With the above-described apparatus configuration, a coating treatment was performed by adding 0.3 parts by mass of the resin composition particle α as an input A to 100.0 parts by mass of the magnetic carrier core a. During the coating process, the processing time was 10 minutes, and the peripheral speed of the outermost end of the stirring member 3 was adjusted to 11 m / sec so that the power of the drive unit 8 was constant at 3.5 kW. Table 3 shows the coating treatment conditions.

  After the processing time has elapsed and the rotation of the rotating body 2 has stopped, the raw material charging port 5 is opened with the processed material entering the main body casing 1, and 1.7 parts by mass of the resin composition particles α as the input amount B. In addition, coating treatment was performed under the same operating conditions as described above. The obtained magnetic carrier was subjected to magnetic beneficiation, and the residual resin composition particles were separated by a circular vibrating sieve equipped with a screen having a diameter of 500 mm and an opening of 75 μm to obtain a magnetic carrier.

  The obtained magnetic carrier has an average circularity of 0.978, the proportion of magnetic carriers having a circularity of 0.900 or less is 0.1% by number, and the residual resin composition particles in the magnetic carrier are 2.0%. % By volume.

The obtained magnetic carrier was evaluated according to the following criteria. The evaluation results are shown in Table 4.

[Evaluation of surface condition of magnetic carrier]
The obtained magnetic carrier was observed using an electron microscope (SEM) at a magnification of 2,000 so that the entire magnetic carrier could be accommodated in one field of view. This observation was performed 15 times, and the surface state of the magnetic carrier was evaluated according to the following criteria. The evaluation C or higher is a practical level in the present invention. In this example, as shown in FIG. 3, there is no particle interface in the coating layer of the resin composition particles, and the resin composition particles are uniformly coated on the surface of the magnetic carrier core. Was confirmed.
A: Very good. Zero magnetic carriers with grain interfaces.
B: Good. Three magnetic carriers with particle interfaces.
C: No problem in practical use. Five magnetic carriers with grain interfaces.
D: Somewhat bad. Seven magnetic carriers with grain interfaces.
E: Bad. There are 10 or more magnetic carriers with grain interfaces.

[Change rate of image density]
To 90.0 parts by mass of the obtained magnetic carrier, 10.0 parts by mass of the above toner was added and mixed with a V-type mixer to obtain a two-component developer. The obtained two-component developer was evaluated under the following conditions using a Canon full color copying machine IRC3220N.

In the evaluation, as an initial evaluation, the development bias was adjusted so that the development amount of the toner on the photoconductor was 0.6 g / cm ^{2 in} an environment of 30 ° C. and 80% RH, and an image was output. Next, as in the initial evaluation, a fixed amount of toner was replenished with an image having a printing ratio of 1%, and 10,000 sheets (10 k) of images were output, and the image density after 10 k durability was measured.

  For the image density, a solid image was output, density measurement was performed with a densitometer X-Rite500 type, and an average value of 6 points was taken as the image density. The image density change rate D10 / D1 was calculated when the initial image density was D1 and the image density after 10 k endurance was D10, and was judged according to the following criteria.

The evaluation C or higher is a practical level in the present invention.
A: Very good. The image density change rate D10 / D1 is 95% or more.
B: Good. Image density change rate D10 / D1 is 85% or more and less than 95%.
C: No problem in practical use. Image density change rate D10 / D1 is 75% or more and less than 85%.
D: Somewhat bad. The image density change rate D10 / D1 is 65% or more and less than 75%.
E: Bad. Image density change rate D10 / D1 is less than 65%.

[Maintenance of Q / M (mC / kg) on photoconductor]
In the evaluation, first, as an initial evaluation, when the amount of toner on the photoreceptor reaches 0.6 g / cm ^{2 in} an environment of 30 ° C. and 80% RH, the toner on the photoreceptor is replaced with a metal cylindrical tube. Aspiration was collected by a cylindrical filter. At that time, the charge quantity Q stored in the condenser through the metal cylindrical tube and the collected toner mass M are measured, and the charge quantity Q / M (mC / kg) per unit mass is calculated from the measured quantity. It was set as Q / M (mC / kg) on the body.

The above-mentioned initial photoconductor Q / M is 100%, and then the photoconductor is endured for 10,000 sheets (10k) in an image with a print ratio of 40% in an environment of 30 ° C. and 80% RH, and after 10 k endurance. The maintenance ratio of the upper Q / M was calculated and judged according to the following criteria. The evaluation C or higher is a practical level in the present invention.
A: Very good. The Q / M maintenance rate on the photoreceptor is 90% or more.
B: Good. The Q / M maintenance rate on the photoreceptor is 80% or more and less than 90%.
C: No problem in practical use. The Q / M maintenance rate on the photoreceptor is 70% or more and less than 80%.
D: Somewhat bad. The Q / M maintenance rate on the photoreceptor is 60% or more and less than 70%.
E: Bad. The Q / M maintenance rate on the photoreceptor is less than 60%.

[leak]
The evaluation was made by visually evaluating the toner layer on the photoconductor and the output solid image when the amount of toner on the photoconductor reached 0.4 g / cm ^{2 in} an environment of 30 ° C. and 80% RH. Judgment was made based on the following criteria.

Leakage is a phenomenon in which when the toner coverage on the surface of the magnetic carrier decreases, the charge moves from the developing carrier to the surface of the photosensitive member via the magnetic carrier. When the leakage phenomenon occurs, the potential of the latent image becomes the developing potential. It converges and is no longer developed. As a result, a leak mark (a part where the toner layer is removed and the photosensitive member can be seen) is generated in the toner layer on the photoconductor, or a leak mark (a white part) is generated in the solid image when the leak is significant. Or Evaluation C or higher is a practical level in the present invention.
A: Very good. No leak mark is seen in the toner layer on the photoreceptor.
B: Good. Some leak marks are seen in the toner layer on the photoreceptor.
C: No problem in practical use. Although there is a leak mark on the photoconductor, it is not seen in the solid image.
D: Somewhat bad. Some leak marks are also seen in the solid image.
E: Bad. A large number of leak traces can be seen on the entire solid image.

[Maintenance of Q / M (mC / kg) after standing]
Evaluation was performed at 23 ° C. and 50% RH in an image with a printing ratio of 30% for 10,000 sheets (10 k), and after evaluating developability, the developer was removed from the machine, After being left for 72 hours in an environment of 90% RH, the developing device was mounted in the apparatus again, and the charge amount Q / M per unit mass on the photoreceptor was measured.

The Q / M on the photoconductor at the time of image evaluation after 10,000 sheets (10k) was defined as 100%, and the maintenance ratio of the Q / M on the photoconductor after standing for 72 hours was calculated and judged according to the following criteria. The evaluation C or higher is a practical level in the present invention.
A: Very good. The Q / M maintenance rate on the photoconductor is 90% or more, which is very high.
B: Good. The Q / M maintenance rate on the photoreceptor is 80% or more and less than 90%.
C: No problem in practical use. The Q / M maintenance rate on the photoreceptor is 70% or more and less than 80%.
D: Somewhat bad. The Q / M maintenance rate on the photoreceptor is 60% or more and less than 70%.
E: Bad. The Q / M maintenance rate on the photoreceptor is less than 60%.

[Example 2]
In this example, the coating treatment was performed in the same manner as in Example 1 except that the resin composition particle α was 0.6 parts by mass as the input amount A and 2.4 parts by mass as the input amount B. Obtained. Table 3 shows the coating treatment conditions. The magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

  The obtained magnetic carrier has an average circularity of 0.971, the proportion of magnetic carriers having a circularity of 0.900 or less is 0.4% by number, and the residual resin composition particles in the magnetic carrier are 2.9. % By volume.

  Next, the magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

Example 3
In this example, the coating treatment was performed in the same manner as in Example 1 except that the resin composition particle α was 0.3 parts by mass as input A and 1.2 parts by mass as input B, and the magnetic carrier was Obtained. Table 3 shows the coating treatment conditions.

  The obtained magnetic carrier has an average circularity of 0.978, the proportion of magnetic carriers having a circularity of 0.900 or less is 0.2% by number, and the residual resin composition particles in the magnetic carrier are 1.7. % By volume.

  Next, the magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

Example 4
In this example, 0.7 parts by mass was added with the resin composition particle α as the input amount A, and the coating treatment was performed in the same manner as in Example 1.

  After the processing time has elapsed and the rotation of the rotating body 2 has stopped, the raw material charging port 5 is opened with the processed material entering the main body casing 1, and 0.7 parts by mass of the resin composition particles α as the charging amount B In addition, coating treatment was performed under the same operating conditions as described above.

  Further, after the processing time has elapsed and the rotation of the rotating body 2 has stopped, the raw material charging port 5 is opened in a state where the processed product enters the main body casing 1, and 0.7 parts by mass of the resin composition particles α are added. The coating treatment was performed under the same operating conditions as above.

  The obtained magnetic carrier was subjected to magnetic beneficiation in the same manner as in Example 1, and the residual resin composition particles were separated by a circular vibrating sieve to obtain a magnetic carrier. Table 3 shows the coating treatment conditions. The obtained magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

Example 5
In the present example, 0.3 parts by mass was added with the resin composition particle α as the input amount A, and the coating treatment was performed in the same manner as in Example 1.

  After the processing time has elapsed and the rotation of the rotating body 2 has stopped, the raw material charging port 5 is opened in a state where the processed material enters the main body casing 1, and the resin composition particle α is set to 0.6 parts by mass as the charging amount B. In addition, coating treatment was performed under the same operating conditions as described above.

  Furthermore, after the processing time has elapsed and the rotation of the rotating body 2 has stopped, the raw material charging port 5 is opened in a state where the processed product enters the main body casing 1, and 1.2 parts by mass of the resin composition particles α are added. The coating treatment was performed under the same operating conditions as above.

  The obtained magnetic carrier was subjected to magnetic beneficiation in the same manner as in Example 1, and the residual resin composition particles were separated by a circular vibrating sieve to obtain a magnetic carrier. Table 3 shows the coating treatment conditions. The obtained magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

Example 6
In this example, coating treatment was performed under the same operating conditions as in Example 1 except that the magnetic carrier core was b and the resin composition particles were β, to obtain a magnetic carrier. Table 3 shows the coating treatment conditions. The obtained magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

Example 7
In this example, the coating treatment was performed in the same manner as in Example 1 except that the resin composition particle α was 1.0 part by mass as input A and 3.0 part by mass as input B, and the magnetic carrier Got. Table 3 shows the coating treatment conditions. The obtained magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

Example 8
In this example, the coating treatment was performed in the same manner as in Example 1 except that the resin composition particle α was 0.1 part by mass as input A and 0.3 part by mass as input B, and the magnetic carrier Got. Table 3 shows the coating treatment conditions. The obtained magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

Example 9
In this example, coating treatment was performed in the same manner as in Example 1 except that the resin composition particle α was set to 1.7 parts by mass as the input amount A and 0.3 parts by mass as the input amount B. Got. Table 3 shows the coating treatment conditions. The obtained magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

Example 10
In this example, the coating treatment was performed in the same manner as in Example 1 except that the resin composition particle α was 1.0 part by mass as input A and 1.0 part by mass as input B, and the magnetic carrier Got. Table 3 shows the coating treatment conditions. The obtained magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

Example 11
In this embodiment, the shape of the stirring member 3 is the same as that of FIG. 2B, and the overlap width d of the stirring member 3a and the stirring member 3b in FIG. The magnetic carrier was obtained by performing coating treatment in the same manner as in Example 1 except that the content was 0.10 D. Table 3 shows the coating treatment conditions. The obtained magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

Example 12
In this embodiment, the shape of the stirring member 3 is the same as that shown in FIG. 2C, and the overlapping width d of the stirring member 3a and the stirring member 3b in FIG. The magnetic carrier was obtained by performing the coating treatment in the same manner as in Example 1 except that 0.30D was used. Table 3 shows the coating treatment conditions. The obtained magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

[Reference example]
In this reference example, except that 2.0 parts by mass of the resin composition particles α was added, a coating treatment was performed in the same manner as in Example 1 to obtain a magnetic carrier. Table 3 shows the coating treatment conditions.

  The obtained magnetic carrier was subjected to magnetic beneficiation, and the residual resin composition particles were separated by a circular vibration sieve equipped with a screen having a diameter of 500 mm and an opening of 75 μm.

Furthermore, in this reference example, the obtained magnetic carrier was used with a fixed mesh surface wind screen high voltor (NR-300 type, manufactured by Shin Tokyo Machine Co., Ltd .: an air brush attached to the back of a wire mesh), and a diameter of 300 mm, Two screens with an opening of 75 μm and an opening of 20 μm are installed, placed on an air flow with an air volume of 6 Nm ³ / min, a magnetic carrier is supplied at a supply rate of 50 kg per hour, and residual resin composition particles are separated. A magnetic carrier was obtained. The obtained magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

[Comparative Example 1]
In this comparative example, 90.0 parts by mass of toluene was added to 10.0 parts by mass of the resin composition particles α to produce a resin solution (solid content concentration 10%). The coating treatment was carried out using NIPPONDAL.

  The coating treatment conditions were as follows: the temperature inside the apparatus was heated to 60 ° C. while introducing nitrogen, and the resin solution was added to 10 parts by mass (corresponding to 1.0 part by mass as the solid content) with respect to 100 parts by mass of the magnetic carrier core a. ) Was applied, and the coating treatment was carried out at a coating time of 30 minutes. After completion of the coating treatment, 10 parts by mass (corresponding to 1.0 part by mass as the solid content) of the resin solution was further added, and the coating treatment was performed under the above-described coating conditions.

  After completion of the coating treatment, the solvent was completely dried, heat-treated at 100 ° C. for 2 hours under reduced pressure using a vacuum dryer, crushed after cooling, and magnetically separated. Next, the residual resin composition particles were separated by a circular vibration sieve equipped with a screen having a diameter of 500 mm and an opening of 75 μm, thereby obtaining a magnetic carrier. The obtained magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

[Comparative Example 2]
In this comparative example, the coating process was performed using a high-speed stirring mixer (High Flex Gral LFS-GS-2J type manufactured by Fukae Pautech Co., Ltd.) as the coating apparatus.

  The coating treatment conditions were as follows: 1.0 part by mass of the resin composition particle α as an input A with respect to 100 parts by mass of the magnetic carrier core particle a, and a jacket installed outside the casing of the high-speed stirring mixer main body as a heat medium Oil was allowed to flow, the inside of the main casing was heated to 108 ° C., and the agitator tip peripheral speed was 11 m / sec, followed by stirring for 15 minutes.

  After completion of the stirring, 1.0 part by mass of the resin composition particles α as an input amount B is further added, and the inside of the high-speed stirring mixer main body casing is heated to 108 ° C. and stirred for 15 minutes to perform a coating treatment. It was. The obtained magnetic carrier was subjected to magnetic beneficiation, and the residual resin composition particles were separated by a circular vibrating sieve equipped with a screen having a diameter of 500 mm and an opening of 75 μm to obtain a magnetic carrier. The obtained magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

[Comparative Example 3]
In this comparative example, the coating apparatus was coated using the same apparatus as in comparative example 2. The coating treatment condition is that 0.7 parts by mass of the resin composition particles α is added to 100 parts by mass of the magnetic carrier core a, oil is passed as a heat medium through a jacket installed outside the apparatus body casing, It heated so that it might become 108 degreeC, the stirrer front-end | tip peripheral speed was 11 m / sec, it stirred for 10 minutes, and the coating process was performed.

  After the processing time has elapsed and the rotation of the rotating body 2 has stopped, the raw material charging port is opened with the processed material in the main body casing 1, and 0.7 parts by mass of the resin composition particle α is added as the charging amount B. The coating treatment was performed under the same operating conditions as above.

  Further, after the processing time has elapsed and the rotation of the rotating body has stopped, the raw material charging port is opened with the processed material entering the main body casing 1, and 0.7 parts by mass of the resin composition particles α are added. The coating treatment was performed under the same operating conditions.

  The obtained magnetic carrier was subjected to magnetic beneficiation, and the residual resin composition particles were separated by a circular vibrating sieve equipped with a screen having a diameter of 500 mm and an opening of 75 μm to obtain a magnetic carrier. The obtained magnetic carrier was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

  1: main body casing, 2: rotating body 3, 3a, 3b: stirring member, 4: jacket, 5: raw material inlet, 6: product outlet, 7: central shaft, 8: drive unit, 9: processing space, 10 : Side surface of rotating body, 11: rotation direction, 12: feed direction (drive unit direction), 13: feed direction (counter drive unit direction), 16: inner piece for raw material inlet, 17: inner piece for discharging magnetic carrier d: Interval indicating the overlapping portion of the stirring member D: Maximum width of the stirring member

Claims (5)

Using coating processing apparatus having a means for the coating treatment by a mechanical impact force, a method for producing a magnetic resistance carrier that have a that the coating process overturn the resin composition particles to the surface of the magnetic carrier core particles ,
The coating apparatus is that Yusuke least a rotating body in which a plurality of agitating member has a surface, a driving unit for rotationally driving the rotation body, a body casing which is provided with a the stirrer拌部material and gap device And
In the coating treatment step, the magnetic carrier core particles and the resin composition particles are rotated in the direction of the drive unit, which is one direction of the axial direction of the rotating body, by rotating the rotating body and using a part of the stirring member. The magnetic carrier core particles and the resin composition particles are fed by the other part of the stirring member in a direction opposite to the driving unit, which is the reverse direction of the axial direction of the rotating body, in the direction of the driving unit. And by repeating the feeding in the direction of the counter-drive portion, the coating treatment of the resin composition is performed on the surfaces of the magnetic carrier core particles,
As the coating treatment, the resin composition particles are added and then the first coating treatment is performed, and then the resin composition particles are further charged and the coating treatment is performed, so that the resin composition particles are charged in a plurality of times. And the manufacturing method of the magnetic carrier characterized by performing the coating process in multiple times.   As the resin composition particles are added, the first coating treatment is performed, and the resin composition particles are further charged and the coating treatment is performed. When the coating treatment is performed, the amount of the resin composition particles to be charged at the first time is A part by mass, and the amount of the resin composition particles to be charged after the first time is B parts by mass, the magnetic carrier core particles are 100.0 parts by mass. On the other hand, the input amount A of the resin composition particles is 0.1 part by mass or more and 1.0 part by mass or less, and the method for producing a magnetic carrier according to claim 1. 3. The method for producing a magnetic carrier according to claim 1, wherein the relationship between the input amount A of the resin composition particles and the input amount B of the resin composition particles satisfies the following formula.
A <B   A magnetic carrier produced by coating the surface of the magnetic carrier core particle with the resin composition particle, wherein the magnetic carrier is produced by the production method according to claim 1. The magnetic carrier is characterized in that, in the circularity distribution of circularity (a) obtained from the following formula, the number of magnetic carrier particles having a circularity (a) of 0.900 or less is 10.0% by number or less. The magnetic carrier according to claim 4.
Circularity a = L ₀ / L
[L ₀ represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the particle image. ]

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