JP2016191736A - Fluidity evaluation method for electrophotographic developer ferrite core material and ferrite carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluidity evaluation method for, for example, an electrophotographic developer ferrite carrier core material, which is able to select characteristic function efficiently without interrupting measurement even if a particle diameter is small.SOLUTION: In a fluidity evaluation method for an electrophotographic developer ferrite carrier core material and a ferrite carrier, in which ferrite particles are evaluated and the holes of the ferrite particles are filled with resin and/or their surfaces are coated with resin and evaluated, specific vibration is applied to an accommodation member accommodating the ferrite particles, and the resin-filled and/or resin-coated ferrite particles. The weights of the ferrite particles and resin-filled and/or resin-coated ferrite particles flowing out from the accommodation member by this vibration are measured. On the basis of the measured weights of the ferrite particles and so on, data about the degree of flow of the ferrite particles and so on per unit time are obtained. Using the data, the employed fluidity evaluation method for the electrophotographic developer ferrite carrier core material and ferrite carrier evaluates the characteristics of the ferrite particles, and so on.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a ferrite carrier core material for an electrophotographic developer used in a two-component electrophotographic developer used in a copying machine, a printer, and the like, and a ferrite carrier fluidity evaluation method.

  The ferrite carrier core material for an electrophotographic developer is a ferrite particle having a shape typified by a substantially spherical shape, and generally, the concept as a ferrite powder in which ferrite particles are aggregated is applied.

  Further, the ferrite carrier is a particle containing a resin on the ferrite particle surface and / or inside the ferrite particle in order to impart desired electrical characteristics, and the concept of ferrite powder is applied in the same manner as the ferrite particle. That is, the ferrite carrier includes a resin-coated ferrite carrier, a resin-filled ferrite carrier, and a resin-coated resin-filled ferrite carrier (hereinafter collectively referred to as a ferrite carrier unless otherwise specified).

  Therefore, evaluation methods generally applied to powders have been widely applied to the quality evaluation of these ferrite carrier core materials and ferrite carriers.

  Conventionally, a ferrite carrier core material and a ferrite carrier have been required to have good fluidity in order to improve the mixing property with the toner, and many proposals have been made that define the fluidity.

  Patent Document 1 (Japanese Patent Laid-Open No. 2006-337828) describes a ferrite carrier core material for electrophotography having a fluidity in the range of 21.9 to 48.9 seconds / 50 g. In addition, the ferrite carrier core material described in Patent Document 1 has an average particle size of preferably 15 to 120 μm. As the average particle size becomes smaller, the fluidity becomes worse, and a ferrite carrier core material of 20 μm or less is a device in which the ferrite carrier core material (ferrite particles) is an apparatus depending on the core material composition or the firing atmosphere of the core material. The flow rate cannot be calculated. In order to maximize the effect on image quality improvement, it is necessary to reduce the particle size of the carrier, and the surface of the ferrite particle as the ferrite carrier core material is appropriate for sufficiently exerting the charge imparting ability. It is described that it is better to have unevenness.

  Patent Document 2 (Japanese Patent Laid-Open No. 2002-357930) describes a carrier for an electronic developer in which the product of apparent density and fluidity is in a certain range, and the fluidity is in the range of 27.9 to 44.0 seconds / 50 g. It is described that. This Patent Document 2 also describes that the small particle size carrier has poor fluidity, and the volume average particle size is preferably 30 to 80 μm.

  Patent Document 3 (Japanese Patent Laid-Open No. 2006-337579) describes the fluidity of a ferrite core material for resin-filled carriers and magnetic powder-dispersed carrier particles. The ferrite core material for resin-filled carriers and the magnetic powder-dispersed carrier particles have a lower apparent density and a fluidity of 38.3 to 57 compared to the ferrite carrier core materials or carriers described in Patent Documents 1 and 2. Tended to be slow due to the range of 9 seconds / 50 g. Further, as in Patent Document 1, the fluidity deteriorates when the average particle size becomes small, and the ferrite carrier core material of about 20 μm is a ferrite in the specified measurement method depending on the core material composition or the firing atmosphere of the core material. Since the core material does not flow from the device, the fluidity cannot be measured. The magnetic powder-dispersed carrier particles have a drawback in that the residual magnetization and coercive force are increased, so that the flowability of the developer is deteriorated. According to the prescribed measurement method, the magnetic powder-dispersed carrier particles are removed from the apparatus. Since it does not flow, the fluidity cannot be measured.

  Since the fluidity according to these patent documents measures the time of the powder flowing out of the orifice at the bottom of the funnel due to gravity by a method according to JIS-Z2502 (metal powder fluidity test method), the particle size is If the particle size is reduced, powder such as ferrite carrier core material will not flow out of the orifice and will clog in the middle, and flow will stop, and the fluidity will change with each measurement due to the unevenness of each powder particle. However, appropriate evaluation was difficult.

  Therefore, there is a need for a ferrite carrier core material for an electrophotographic developer used in a two-component electrophotographic developer and a technology for simply and accurately evaluating the fluidity of the ferrite carrier. Is known, for example, as a vibrating capillary type granular material fluidity evaluation apparatus and a granular material fluidity evaluation method described in Patent Document 4 (International Publication No. 2006/115145).

  However, even if the method for evaluating the fluidity of the granular material described in Patent Document 4 is used, the characteristic function of the ferrite carrier core material and ferrite carrier having a small particle diameter cannot be efficiently selected.

JP 2006-337828 A JP 2002-357930 A JP 2006-337579 A International Publication No. 2006/115145

  An object of the present invention is to provide a ferrite carrier core material for an electrophotographic developer and a method for evaluating the fluidity of a ferrite carrier that can efficiently select characteristic functions without interrupting measurement even when the particle size is small. .

  As a result of the study, the inventors of the present invention, as described in Patent Document 4, the ferrite carrier core material and the ferrite carrier that flow through the vibrating tube flow without difficulty without depending on the particle diameter or the sample form, It was found that the characteristics unique to the sample were reflected in order to produce a difference in the starting point of the flow or the flow amount per unit time. Further, it has been found that measurement variation is suppressed by applying vibration to the housing member in advance for a predetermined time and applying compression to the target ferrite carrier core material and the like. The present invention has been made based on these findings.

  That is, the present invention is a method for evaluating the fluidity of a ferrite carrier core material for an electrophotographic developer comprising ferrite particles, wherein vibration is applied to an accommodation member containing the ferrite particles at a predetermined rate of acceleration for a predetermined time. The weight of the ferrite particles flowing out of the housing member due to the applied vibration is measured, and the flow rate data of the ferrite particles per unit time is obtained based on the measured weight of the ferrite particles. The present invention provides a method for evaluating the fluidity of a ferrite carrier core material for an electrophotographic developer, characterized in that the properties of the ferrite particles are evaluated.

Further, the present invention is a method for evaluating the fluidity of a ferrite carrier for an electrophotographic developer in which pores of ferrite particles are filled with resin and / or the surface is coated with resin,
The housing member housing the resin-filled and / or resin-coated ferrite particles is given vibration at a predetermined rate of acceleration for a predetermined time, and the weight of the resin-filled and / or resin-coated ferrite particles flowing out of the housing member by the applied vibration. The flow rate data of the resin-filled and / or resin-coated ferrite particles per unit time is obtained based on the measured weight of the resin-filled and / or resin-coated ferrite particles, and the flow rate data is used. The present invention provides a method for evaluating the fluidity of a ferrite carrier for an electrophotographic developer, wherein the characteristics of the resin-filled and / or resin-coated ferrite particles are evaluated.

  In the above fluidity evaluation method of the present invention, it is desirable to apply vibration to the containing member for containing powder for a predetermined time while compressing the target powder with the outflow hole port closed before performing the measurement.

  The ferrite carrier core material for an electrophotographic developer according to the present invention and the flowability evaluation method of the ferrite carrier can perform measurement corresponding to the reduction in the particle size of the ferrite carrier core material and the ferrite carrier by multifaceted information, The properties of ferrite carrier core material and ferrite carrier as powder can be grasped in detail. Further, the functions possessed by the ferrite carrier core material and the ferrite carrier can be selected at a level that has not existed before.

It is a figure which shows the typical structure of the measuring apparatus used for the fluidity | liquidity measuring method which concerns on this invention. It is a figure which shows the flowchart of the computer processing in the measuring apparatus used for the fluidity | liquidity measuring method which concerns on this invention. It is a graph which shows an example of the profile of the increase rate of the vibration acceleration used in the case of the computer processing of FIG. It is a graph which shows the powder mass flow rate per unit time. It is a graph which shows the total discharge amount of powder per unit time.

Hereinafter, modes for carrying out the present invention will be described.
FIG. 1 is a diagram showing a schematic configuration of a measuring apparatus used in the fluidity measuring method according to the present invention.

  The fluidity measurement method according to the present invention applies vibration to the ferrite carrier core material for an electrophotographic developer or to a housing member that houses the ferrite carrier, and the amplitude of the applied vibration and the discharged vibration are discharged from the housing member. This is a method of calculating an evaluation value for evaluating the fluidity based on the weight of the carrier core material or ferrite carrier.

  As shown in FIG. 1, the flow measuring device according to the embodiment of the present invention mainly includes a flow unit 1, a vibrator 2, a laser vibration measuring device 3, an electronic balance device 4, and a computer (computing). Device) 5.

  The flow section 1 includes a pipe 11, a horizontal rod 12 that supports the pipe 11 so as to be substantially vertical (substantially parallel to the vertical direction G), and a stand 13 that indicates the horizontal rod 12. Yes.

  The tube 11 is a housing member that houses a ferrite carrier core material or a ferrite carrier (hereinafter, collectively referred to as powder), for example, a hopper portion 111 for storing powder, and a flowing powder passing therethrough. And a tube portion 112 to be provided. The hopper portion 111 has an inlet 1111 opened at the upper end so that powder can be charged, and the powder inlet 1111 through the outlet 1112 allow the powder to smoothly flow to the outlet 1112 from which the powder is discharged. It has a funnel shape with a small diameter. The pipe portion 112 has an upper end inflow port 1121 connected to the discharge port 1112 of the hopper portion 111, and a narrow tube portion 1122 having a smaller inner diameter is formed at the lower end. The tube 11 is supported by the horizontal rod 12 at the upper end of the tube portion 112.

  The vibrator 2 is a device that vibrates the tube 11 at a predetermined frequency and amplitude (in the XX direction) in accordance with a control signal from the controller 20, and includes a vibrator main body 21 that generates vibration, and the vibration. For example, an electromagnetic vibrator, an electrostatic vibrator, an electrostrictive vibrator, a vibration motor, or the like can be used as the main body 21 as appropriate. The vibrator main body 21 may be a piezoelectric sounding vibrator configured to include a piezoelectric element. In the piezoelectric sounding vibrator, the amplitude and frequency (frequency) of vibration can be controlled independently, so that the amplitude can be easily and continuously changed while fixing the frequency to a predetermined frequency. There are advantages you can do. The vibration transmitting member 22 is connected to the lower end of the tube portion 112 on the side where the thin tube portion 1122 is formed, and the vibration generated in the vibrator main body 21 is propagated to the tube 11.

  The laser vibration measuring device 3 is a device that measures the amplitude of the tube 11 and outputs the measured amplitude to the computer 5, and includes, for example, a laser vibration measuring device main body 31 and a probe 32. The laser vibration measuring device main body 31 causes the probe 32 to irradiate and irradiate the laser light to the narrow tube portion 1122 near the discharge port 1123 and pass the reflected light through the lens to form a spot on the optical position detection element. The position of the reflected light spot is detected at a preset sampling interval (for example, every second), the amplitude is calculated by obtaining the displacement amount to the object based on the principle of triangulation, and the calculation result is calculated by the computer 5. Output to. In this embodiment, since the vicinity of the discharge port 1123 of the tube 11 from which the powder is discharged is an open end of vibration, the laser vibration measuring instrument 3 is thus a narrow tube in the vicinity of the discharge port 1123 of the tube 11. It arrange | positions so that the amplitude of the part 1122 may be measured and the measurement result may be output to the computer 5. FIG.

  The electronic balance device 4 is a device that measures the weight of the powder discharged from the hopper portion 111 through the tube portion 112 and outputs the measured weight to the computer 5. In the electronic balance device 4, a weighing table 41 on which a measuring object whose weight is to be measured is placed below the outlet 1123 of the tube 11. Then, the electronic balance device 4 receives the powder discharged from the tube portion 11 by the weighing table 41, measures its weight at a predetermined sampling interval (for example, every second), and measures this. The weight is digitally output to the computer 5.

  The computer 5 issues a control command signal to the controller 20 so that the vibrator 2 gives a desired frequency and amplitude of vibration, and based on the amplitude measured by the laser vibration measuring device 3 and the weight measured by the electronic balance device 4. This is a device for calculating an evaluation value for evaluating the fluidity of the powder. As such a computer 5, a general-purpose personal computer can be used. The display device 51 displays the calculation result such as the previous evaluation value based on a signal from the computer 5.

  Next, the evaluation method regarding the fluidity | liquidity of the powder (ferrite carrier core material and ferrite carrier) of this invention using the fluidity | liquidity measuring apparatus comprised as mentioned above is demonstrated. When measuring the evaluation value with the fluidity measuring device, the user first activates the computer 5, the laser vibration measuring device 3 and the electronic balance device 4 to set the vibration frequency of the vibrator 2 in the computer 5 and the tube 11. Preparation of measurement is performed by putting the powder to be measured into the hopper 111 of the hopper portion 111 from the inlet. Then, the user instructs the computer 5 to start measurement.

  When receiving an instruction to start measurement, the computer 5 instructs the controller 20 to vibrate the vibrator 2 for a predetermined time at a predetermined frequency and amplitude, and applies vibration to the tube 11 by the vibrator 2. In addition, a shutter (not shown) provided at the discharge port 1123 opens almost simultaneously with the start of vibration of the vibrator 2, and discharge of the powder is started. The laser vibration measuring device 3 measures the amplitude of vibration of the tube 11 at a predetermined sampling interval, and outputs the measured amplitude of the tube 11 to the computer 5. Further, the electronic balance device 4 measures the weight of the powder discharged at a predetermined sampling interval, and outputs the measured weight of the powder to the computer 5. Data output from the laser vibration measuring device 3 and the electronic balance device 4 is stored in a storage unit or the like of the computer 5 (not shown).

  When the discharge of the powder is completed, the computer 5 creates a graph of the flow rate per unit time based on the output from the laser vibration measuring device 3 and the output from the electronic balance device 4 stored in the storage unit. The graph is output to the display device 51.

  Next, the processing operation of the computer 5 when the fluidity measuring device measures the fluidity of the powder will be described. FIG. 2 is a diagram showing a flowchart of processing by the computer 5 of the fluidity measuring device, and FIG. 3 is a graph showing an example of a profile of an increase rate of vibration acceleration used in the processing by the computer 5.

In the present embodiment, before executing the process by the computer 5, the user sets the rate of increase in vibration acceleration as an initial setting in advance. FIG. 3 shows a profile when 5.2 [m / s ³ ] is set as the rate of increase in vibration acceleration and 60 [sec] is set as the vibration time. In the measurement, the measurement ends when the vibration time has passed 60 [sec]. Further, the parameters related to the rate of increase in vibration acceleration and vibration time as described above can be arbitrarily set based on the type and amount of powder to be measured.

  As described above, when the user sets parameters, sets the powder to be evaluated in the hopper 111, and instructs the computer 5 to start measurement, the computer 5 starts measurement from step S100.

  When the measurement process is started by the computer 5 in step S100, subsequently, in step S101, the vibration of the set acceleration rate is applied to the tube 11 by the vibrator 2 at a constant frequency. Next, the controller 20 is instructed.

  In the fluidity measuring apparatus used in this embodiment, the frequency can be arbitrarily set based on the type and amount of the powder to be measured.

  In subsequent step S102, the amplitude data sampled by the laser vibration measuring instrument 3 and the weight data sampled by the electronic balance device 4 are acquired and stored in the storage unit.

  In the next step S103, it is determined whether or not the vibration time set in the initial setting has elapsed. When the determination result is YES, the process proceeds to step S104, and when it is NO, the process returns to step S102 again.

  In step S104, the amplitude data sampled by the laser vibration measuring instrument 3 and the weight data sampled by the electronic balance device 4 are acquired and stored in the storage unit.

  In step S104, the computer 5 creates a graph of the change in flow rate per unit time based on the obtained weight data of the electronic balance device 4, and in step S105, an evaluation value for evaluating the fluidity of the powder is obtained. The calculation process is completed in step S105.

Steps S104 and S105 will be described in more detail. FIG. 4 shows an example of a graph of the transition of the flow rate (mass flow rate) per unit time created in step S104. The computer 5 is a data set (D ₁ , D ₂ , D ₃ ,... D ₂₀ , D) as flow data (time, mass flow) based on the obtained weight data of the electronic balance device 4. ₂₁ ) Calculate. Based on such a data set, the computer 5 creates a graph as shown in FIG. 4 and displays it on the display device 51.

Next, step S105 will be described in more detail. In step S105, an evaluation value for evaluating the fluidity of the powder is calculated. These evaluation values are calculated as data sets (D ₁ , D ₂ , D ₃ ,... D ₂₀ ,. It is calculated from D _21).

  In the fluidity measuring device used in the present embodiment, the evaluation value of the maximum flow rate is calculated as an evaluation value for evaluating the fluidity of the powder, and each evaluation value calculation method will be described below.

FIG. 4 also shows a calculation example of the maximum flow rate value in the fluidity measuring device according to the present embodiment. The maximum flow rate value of the evaluation value calculated by the fluidity measuring device is the maximum value (in this example, obtained from the flow rate data set (D ₁ , D ₂ , D ₃ ,... D ₂₀ , D ₂₁ )). a D mass flow rate value when the _5).

  As described above, according to the present invention, the characteristics of the fluidity of the powder when the vibration acceleration of the tube 11 is increased by the vibrator 2 are extracted, and the powder includes multifaceted information than before. It is possible to obtain an evaluation value of the fluidity of

  This is because, as shown in FIG. 4, together with the maximum flow value of the powder, the timing (elapsed time) at which the maximum value is shown becomes clear, and at the same time, the vibration time of the powder is 30 [sec] as shown in FIG. This is because information on the total amount of emissions when elapses of time is also obtained.

  In order to compress the powder for a predetermined period of time by applying vibration to the housing member that contains the powder while the outlet hole port is closed before performing the measurement, a shutter (not shown) provided in the discharge port 1123 is used. What is necessary is just to add a vibration to the vibrator 2 with closing).

  In such a fluidity evaluation method according to the present invention, it is desirable that the frequency of vibration for starting the flow is 1 to 600 Hz. Effective flow can be initiated at frequencies in this range. If the frequency of vibration is less than 1 Hz, the energy required for the powder to flow through the tube is not applied, and particles are clogged near the outflow hole and measurement is not started. On the other hand, if the frequency of vibration is greater than 600 Hz, the energy required for the powder to flow through the tube is saturated and does not make sense, or the time to start the flow is too fast, And lot differences cannot be confirmed.

  Moreover, in the fluidity evaluation method according to the present invention, it is desirable that the maximum amplitude of vibration for starting the flow is 1-1000 μm. Effective flow can be initiated with a maximum amplitude in this range. If the maximum amplitude is less than 1 μm, the energy required for the powder to flow through the tube is not applied, and the powder is clogged near the outflow hole and measurement is not started. Also, if the maximum amplitude is greater than 1000 μm, the energy required for the powder to flow through the tube is saturated and does not make sense or the time to start the flow is too fast, And lot differences cannot be confirmed.

In the fluidity evaluation method according to the present invention, the rate of increase in vibration related to the flow rate per unit time is desirably 3.5 to 9.0 m / s ³ . An appropriate amount of flow can be obtained with an increase rate of vibration within this range. If the rate of vibration increase is less than 3.5 m / s ³ , the amount of flow per unit time is small, and it takes time to confirm the difference between the type of powder and the lot, which is inefficient. On the other hand, if the rate of vibration increase is greater than 9.0 m / s ³ , vibration energy is instantaneously applied to the powder, so that particles are clogged near the outflow hole and measurement is not started. For this reason, the flow amount per unit time cannot be calculated.

  In the fluidity evaluation method according to the present invention, it is desirable that the vibration time related to the flow rate per unit time is 30 to 90 sec. An appropriate amount of flow can be obtained with an oscillation time in this range. If the vibration time is less than 30 sec, the flow amount data is relatively low because the time during which vibration is applied is too short. For this reason, it is inefficient because differences in powder types and lots cannot be confirmed. Further, if the vibration time is longer than 90 sec, it is inefficient because it requires a measurement time.

  In the present invention, it is desirable to apply vibration to the containing member for containing the powder for a predetermined time and to compress the powder while the outlet hole is closed before the measurement. By applying compression in this way, the pressure difference between the upper part and the lower part (outflow hole) of the housing member associated with the number of flows can be minimized, and variations in measurement accuracy are suppressed. When compression is not applied, a large pressure difference is generated between the upper part and the lower part (outflow hole) of the housing member during measurement. Therefore, when continuous measurement is performed, the flow state fluctuates every time the measurement is repeated. As a result, the measurement accuracy varies greatly. In addition, in order to apply compression to the powder, there is no particular limitation on the time for applying vibration to the housing member for housing the powder while closing the outlet hole port, but about 1 to 10 seconds is preferable.

[Example 1]
In this example, a ferrite carrier core material that flows in a vibrating tube and a method for evaluating the fluidity of the ferrite carrier will be described.

  For the fluidity evaluation apparatus, “DPF-03 manufactured by IMP” was used. At this time, the ferrite carrier core material or the ferrite carrier sample is filled in the tube portion 112 via the hopper portion 111. In addition, although there is no restriction | limiting in particular in the sample filling amount in the pipe part 112, It is preferable that 20-80 weight% exists as a filling rate so that a sample may not run short within measurement time. Further, the measurement data at this time was automatically taken into the personal computer 5.

  As shown in Table 1, a predetermined sampling interval (for example, 1) is set under the conditions of applied vibration (frequency, maximum amplitude, acceleration increase rate, vibration time) and presence / absence of preprocessing by compression. Flow rate data calculated every second) was obtained. From these flow rate data, the total discharge amount from the start to the end of vibration, the maximum mass flow rate, the acceleration index G when showing the maximum mass flow rate, and its variation coefficient were measured. The measurement was repeated 10 times, and these average values were used as final evaluation values. The acceleration index G and the coefficient of variation when indicating the maximum mass flow rate were evaluated as follows.

[Acceleration index G when indicating maximum mass flow rate]
[Equation 1]
Acceleration index G [dimensionless] = vibration acceleration (m / s ² ) / gravity acceleration (m / s ² )

[Coefficient of variation of acceleration index G when indicating maximum mass flow rate]
[Equation 2]
Coefficient of variation (%) of acceleration index G when indicating maximum mass flow rate = (standard deviation / acceleration index G when indicating maximum mass flow rate) × 100

  Here, when the powder is compressed, the pressure difference between the upper part and the lower part (outflow hole) is minimized, and the coefficient of variation (%) becomes smaller. This coefficient of variation (%) means a variation for each measurement. If the coefficient of variation (%) is small, the variation is small. The coefficient of variation (%) is preferably 50% or less, and more preferably 15% or less.

  The results are shown in Table 1 as evaluation results of various ferrite carrier core materials and ferrite carriers. In addition, 14 samples (sample 1 to sample 14) that are considered to be capable of measuring the volume-based average particle diameter were extracted and used as samples, and examples 1-1 to 1-15 were used. .

[Comparative Example 1]
This comparative example is used for comparison with Example 1 described above. For the ferrite carrier core material and the ferrite carrier of Samples 1 to 14, the fluidity was measured by a method according to JIS-Z2502 (metal powder fluidity test method) shown below. The results are shown as Comparative Example 1-1 to Comparative Example 1-15 in Table 2 as evaluation results of various ferrite carrier core materials and ferrite carriers so that they can be compared with Examples.

  Moreover, the volume reference | standard average particle diameter and true density of samples 1-14 were measured as a conventional evaluation item, and it showed in Table 2 collectively. The volume standard average particle diameter and true density were measured as follows.

[Fluidity]
This is carried out in accordance with JIS Z 2502 “Testing method for fluidity of metal powder”, and 50 g of a sample (ferrite carrier core material) is poured into a funnel having an orifice hole diameter of 2.63 mm, and the flow time (seconds) is measured. Note that the measurement was performed in a constant temperature and humidity chamber controlled at a room temperature of 25 ° C. and a humidity of 55%.

[Volume-based average particle diameter]
It is measured using a Nikkiso Co., Ltd. Microtrac particle size analyzer (Model 9320-X100). The refractive index was 2.42, and the measurement was performed in an environment of 25 ± 5 ° C. and humidity 55 ± 15%. Water was used as the dispersion medium. Place 10 g of sample and 80 ml of water in a 100 ml beaker and add 2-3 drops of dispersant (sodium hexametaphosphate). Subsequently, using an ultrasonic homogenizer (UH-150 type manufactured by SMT Co Ltd), the output level was set to 4 and dispersion was performed for 20 seconds. Thereafter, bubbles formed on the beaker surface were removed, and the sample was put into the apparatus.

  In this microtrack, the volume-based particle diameter is measured, and the number-based particle diameter is automatically calculated from the measured value. In general, the relationship between the volume-based average particle size and the number-based average particle size is as follows.

[Equation 3]
Volume-based average particle size = Σ (vi · di) / Σ (vi)
Number-based average particle size = {Σ (vi) / di ² } / {Σ (vi) / di ³ }
Here, di represents the representative particle diameter (μm), and vi represents the volume of the particle having each representative particle diameter di.

The volume-based average particle size referred to here is a particle size of 10%, 50%, and 90% cumulative on the screen display. Number-based median diameter D ₅₀ is calculated from the above equation.

  As a ferrite carrier core material for an electrophotographic developer and a ferrite carrier, the volume-based average particle diameter is preferably 1 to 100 μm, more preferably 1 to 50 μm, and most preferably 5 to 40 μm. If the volume reference average particle diameter of the ferrite carrier core material and the ferrite carrier is less than 1 μm, the particles may be clogged in the measuring apparatus and measurement may not be possible. When the volume reference average particle diameter of the ferrite carrier core material and the ferrite carrier exceeds 100 μm, the difference from the existing apparatus becomes small, and it becomes difficult to examine the flow state between samples, so that it is preferably 100 μm or less.

[True density]
Measurement was performed using a pycnometer in accordance with JIS R9301-2-1. Here, methanol was used as a solvent, and measurement was performed at a temperature of 25 ° C.

The true density of the ferrite carrier core material and the ferrite carrier is preferably 3.0 to 5.5 g / cm ³ . If the true density is less than 3.0 g / cm ³ , particles may be clogged in the measuring apparatus and measurement may not be possible. When the true density exceeds 5.5 g / cm ³ , the difference from the existing apparatus becomes small, and it becomes difficult to examine the flow state between samples.

From the comparison between Example 1 and Comparative Example 1 in Tables 1 and 2, the volume-based median diameter D ₅₀ and the value of the total discharge amount at 30 seconds of the ferrite carrier core material or ferrite carrier flowing in the vibrating tube Can be understood to show a good correlation. It can also be understood that the true density and the value of the maximum mass flow rate of the ferrite carrier core material or ferrite carrier flowing in the vibrating tube show a good correlation. Moreover, in Example 1, the variation coefficient (%) of the acceleration index G was the smallest and the variation was the smallest in Example 1-3 in which preprocessing by compression was performed.

Here, Table 2 (flowability test method for metal powders) JIS-Z2502 of Comparative Example 1 shown in follow fluidity values, particularly volume-based median diameter D ₅₀ is small (small particle diameter) ferrite carrier core material It can be seen that the powder does not flow out from the orifice at the bottom of the funnel, clogs in the middle, stops the flow, and cannot be measured. Further, correlation between flowability value and volume-based median diameter D ₅₀ of the measurable ferrite carrier core material or a ferrite carrier the fluidity value is found to be low. Furthermore, there is no correlation between the fluidity value and the true density. Therefore, it is difficult to use a method according to JIS-Z2502 (metal powder fluidity test method) for the evaluation of the powder characteristics of the ferrite carrier core material or ferrite carrier, and the ferrite carrier core material that flows in a vibrating tube or It becomes clear that the method for evaluating the fluidity of ferrite carriers must be used.

[Reference Example 1]
About the ferrite carrier core material of Samples 1 to 9, firing method, firing temperature, firing atmosphere, particle size distribution (laser diffraction type), volume-based particle diameter (D ₁₀ , D ₁₆ , D ₅₀ , D ₈₄ , D ₉₀ ), powder Body characteristics (BET specific surface area, apparent density, pore volume, peak pore diameter, shape index SF-1, shape index SF-2, Sr elution amount), magnetic characteristics (magnetization, residual magnetization, coercive force) and electrical characteristics ( Bridge resistance) was evaluated, and the results are shown in Tables 3 and 4 as Reference Examples 1-1 to 1-9.

The ferrite carrier core material and the ferrite carrier preferably have a BET specific surface area of 800 to 15000 cm ² / g, and more preferably 1000 to 11000 cm ² / g.

[BET specific surface area]
The BET specific surface area was measured using a specific surface area measuring device (model: Macsorb HM model-1208 (manufactured by Mountec)). About 5 to 7 g of the measurement sample was put in a standard sample cell dedicated to a specific surface area measurement device, accurately weighed with a precision balance, the sample (ferrite particles) was set in the measurement port, and measurement was started. The measurement is performed by a one-point method, and the BET specific surface area is automatically calculated when the weight of the sample is input at the end of the measurement. In addition, as a pretreatment before the measurement, about 20 g of the measurement sample was placed on the medicine wrapping paper, and then deaerated to −0.1 MPa with a vacuum dryer, and it was confirmed that the degree of vacuum had reached −0.1 MPa or less. Then, it heated at 200 degreeC for 2 hours.
Environment: temperature; 10-30 ° C, humidity; 20-80% relative humidity, non-condensing

[Apparent density]
It measured based on JISZ2504. Details are as follows.
1. Apparatus The powder apparent density meter is composed of a funnel, a cup, a funnel support, a support bar and a support base. A balance with a weighing of 200 mg and a weighing of 50 mg is used.
2. Measuring method (1) The sample shall be at least 150 g or more.
(2) The sample is poured into a funnel having an orifice with a hole diameter of 2.5 + 0.2 / −0 mm, and poured until the sample that has flowed out fills the glass and overflows.
(3) Stop the inflow of the sample as soon as it begins to overflow, and scrape the sample raised on the cup flatly with a spatula along the top edge of the cup so as not to give vibration.
(4) Tap the side surface of the cup to sink the sample and remove the sample attached to the outside of the cup, and weigh the sample in the cup with an accuracy of 0.05 g.
3. Calculation The numerical value obtained by multiplying the measured value obtained in 2- (4) above by 0.04 is rounded to the second decimal place by JIS-Z8401 (how to round the numerical value), and the apparent density in units of “g / cm3” And

  The pore volume of the ferrite carrier core material and ferrite carrier is preferably 0.10 to 1.00 ml / g (100 to 1000 μl / g), and the peak pore diameter is preferably 0.20 to 1.00 μm.

(Pore volume)
Measurement of the peak pore diameter and pore volume is performed as follows. That is, it measured using mercury porosimeter Pascal140 and Pascal240 (ThermoFisher Scientific company make). CD3P (for powder) was used as the dilatometer, and the sample was put in a commercially available gelatin capsule having a plurality of holes and placed in the dilatometer. After degassing with Pascal 140, it was filled with mercury and the low pressure region (0 to 400 Kpa) was measured to obtain 1st Run. Next, deaeration and measurement of the low pressure region (0 to 400 Kpa) were performed again to obtain 2nd Run. After 2nd Run, the combined weight of the dilatometer, mercury, capsule and sample was measured. Next, the high pressure region (0.1 Mpa to 200 Mpa) was measured with Pascal240. The pore volume, pore size distribution, and peak pore size of the ferrite particles were determined from the amount of mercury intrusion obtained by the measurement of the high pressure part. Further, when determining the pore diameter, the surface tension of mercury was 480 dyn / cm and the contact angle was 141.3 °.

[Shape index SF-1]
The shape index SF-1 is JSM-6060A manufactured by JEOL Ltd., the acceleration voltage is 20 kV, and the ferrite particles are photographed with SEM in a 450 × field of view so that the ferrite particles do not overlap. Is introduced into the image analysis software (Image-Pro PLUS) manufactured by Media Cybernetics through the interface, and the area (area) and the ferret diameter (maximum) are obtained and calculated from the following formula. is there. The closer the shape of the ferrite particle shape index SF-1 is to a spherical shape, the closer to 100, and the larger the value, the more indefinite. The shape index SF-1 was calculated for each particle, and the average value of 100 particles was defined as the shape index SF-1 of the ferrite carrier core material (ferrite particles).

[Equation 4]
SF-1 = [(R2 / S) × (π / 4)] × 100
R: Ferret diameter (maximum), S: Area (area)

[Shape index SF-2]
The shape index SF-2 is obtained by observing 3000 ferrite particles using a particle size / shape distribution measuring instrument PITA-1 manufactured by Seishin Enterprise Co., Ltd., and using software Image Analysis provided with the apparatus, S (projection area) and L (projection periphery). This is a value calculated from the following formula. As the shape of the ferrite particle is closer to a sphere, the value becomes closer to 100.
As the sample liquid, a xanthan gum aqueous solution having a viscosity of 0.5 Pa · s was prepared as a dispersion medium, and 0.1 g of ferrite particles were dispersed in 30 cc of the xanthan gum aqueous solution. Thus, by appropriately giving the viscosity of the dispersion medium, it is possible to maintain the state in which the ferrite particles are dispersed in the dispersion medium, and the measurement can be performed smoothly. Furthermore, the measurement conditions are (objective) lens magnification of 10 times, filter is ND4 × 2, carrier liquid 1 and carrier liquid 2 are xanthan gum aqueous solutions having a viscosity of 0.5 Pa · s, and the flow rate is 10 μl / sec. The sample liquid flow rate was 0.08 μl / sec.

[Equation 5]
SF-2 = (L2 / S / 4π) × 100
(L represents the projected perimeter, and S represents the projected area)

[Sr elution amount]
50 g of a sample and 50 ml of pH 4 standard solution for pH meter calibration were placed in a 100 ml glass bottle and stirred for 10 minutes with a paint shaker. After completion of the stirring, 2 ml of the supernatant was sampled, a solution diluted with pure water to 100 ml was measured with ICP, and the obtained measured value was multiplied by 50 to obtain the Sr elution value. The pH 4 standard solution used was specified in the pH measurement method of JIS Z 8802.

(Magnetic properties)
The magnetic properties were measured using a vibrating sample magnetometer (model: VSM-C7-10A (manufactured by Toei Industry Co., Ltd.)). The measurement sample (ferrite particles) was packed in a cell having an inner diameter of 5 mm and a height of 2 mm and set in the above apparatus. The measurement was performed by applying an applied magnetic field and sweeping to 3K · 1000 / 4π · A / m. Next, the applied magnetic field was decreased to create a hysteresis curve on the recording paper. From this curve data, the magnetization at an applied magnetic field of 5K · 1000 / 4π · A / m was read. Also, the residual magnetization and coercive force were calculated in the same manner.

[Electrical characteristics]
This electrical property is measured by:
A non-magnetic parallel plate electrode (10 mm × 40 mm) is opposed to the electrode with an interval of 6.5 mm, and 200 mg of a sample (ferrite particles) is weighed and filled between them. A sample is held between the electrodes by attaching a magnet (surface magnetic flux density: 1500 Gauss, area of the magnet in contact with the electrode: 10 mm × 30 mm) to the parallel plate electrodes, a voltage of 1000 V is applied, and the resistance at those applied voltages is insulated. The resistance was measured with a resistance meter (SM-8210, manufactured by Toa Decay Co., Ltd.).

[Reference Example 2]
For the ferrite carriers (resin-coated ferrite carriers) of Samples 10 and 11, the carrier coating resin, the carrier resin coating amount, the number-based median diameter, the BET specific surface area, the electrical resistance, the carrier adhesion, the charge amount, and the surface coverage by XPS And the surface coverage by EDX was evaluated, and the results are shown in Tables 5 and 6 as Reference Examples 2-1 and 2-2.

[Carrier adhesion]
Printing development was performed under appropriate exposure conditions, and the number of white spots due to carrier adhesion on images after 1 k and after 80 k was visually counted.

[Charge amount]
The charge amount is determined by Epping q / m-meter, PES-Laboratorium suction type charge amount measuring device (mesh: 795 mesh, suction pressure: 105 ± 10 mbar, suction time: 90 seconds), and the initial value and the value after 60 hours. Measured and determined. Further, the environmental change rate and the toner density fluctuation rate were obtained based on the following equations. Here, HH is high temperature and high humidity (temperature 30 to 35 ° C., relative humidity 80 to 85%), LL is low temperature and low humidity (temperature 10 to 15 ° C., relative humidity 10 to 15%), and T / D is a toner for the developer. The concentration of is shown.

  The coverage of the ferrite carrier core material surface by the coating layer in the ferrite carrier depends on the surface shape of the ferrite carrier core material, but is preferably 80% or more, more preferably 85% or more, and 100%. The closer it is, the better. When the coverage is 80% or more, occurrence of white spots on the image is suppressed.

[Surface coverage by XPS]
JPS80 manufactured by JEOL Ltd. is used as the XPS measuring device, and the measurement is performed by using MgKα ray as the X-ray source, setting the acceleration voltage to 10 kV, and the emission current to 20 mV. Main elements (usually carbon) and main elements constituting the core material (for example, iron and oxygen when the core material is an iron oxide-based material such as magnetite) (hereinafter, the core material is an iron oxide-based material) It is assumed that this is the case.) Here, the C1s spectrum is measured for carbon, the Si2p spectrum is measured for silicon, the Fe2p3 / 2 spectrum is measured for iron, and the O1s spectrum is measured for oxygen.

  Based on the spectrum of each of these elements, the number of elements of carbon, silicon, oxygen, and iron (AC + ASi + AO + AFe) is determined, and the obtained element number ratio of carbon, silicon, oxygen, and iron is based on the following formula (1). Then, the iron content rate after coating the core material alone and the core material with the coating layer (carrier) was determined, and then the coverage rate was determined by the following formula (2).

[Equation 6]
Iron content rate (at%) = AFe / (AC + ASi + AO + AFe) × 100 (1)

[Equation 7]
Covering rate (%) = {1− (iron content rate of carrier) / (iron content rate of core material)} × 100 (2)

  When a material other than iron oxide is used as the core material, the spectrum of the metal element constituting the core material in addition to oxygen is measured, and the same applies in accordance with the above formulas (1) and (2). If coverage is calculated, the coverage can be obtained.

[Surface coverage by EDX]
The coverage of the ferrite carrier core material surface in the ferrite carrier is obtained by mapping C, Si, O, and Fe under the following measurement conditions, and then determining C, Si, O, and Fe with respect to the area of the ferrite carrier 1 particle by image processing, Furthermore, it calculates by performing the same operation | work with respect to 10 particles or more.
Sample fixing method Carbon tape (Nisshin EM 8mm x 20m type)
Vapor deposition None Acceleration voltage 10 kV
WD 13mm
Aperture diameter 30μm
Presence or absence of drift correction None Presence or absence of use of high current None Time constant 20-30
EDX measurement magnification 1000 times, 3000 times Integration count 100 times Mapping Count mapping (Count / quantitative / simple quantitative)
Characteristic X-ray L-line (L-line / K-line) used for mapping
The mass% was obtained from the obtained mapping spectrum in consideration of the approximate concentration of each element and the correction coefficient.

[Reference Example 3]
For the ferrite carriers (resin-filled ferrite carriers) of Samples 12 to 14, the carrier coating resin, the carrier resin coating amount, the number-based median diameter, the BET specific surface area, the electrical resistance, the carrier adhesion, the charge amount, and the surface coating by XPS Rate and surface coverage by EDX were evaluated, and the results are shown in Tables 7 and 8 as Reference Examples 3-1 to 3-3.

The ferrite carrier core material for an electrophotographic developer according to the present invention and the flowability evaluation method of the ferrite carrier can perform measurement corresponding to the reduction in the particle size of the ferrite carrier core material or the ferrite carrier based on multifaceted information. The properties of the ferrite carrier core material or ferrite carrier powder can be grasped in detail, and the functions of the ferrite carrier core material or ferrite carrier can be selected at an unprecedented level. As a result, it is possible to design and select high-value-added functions by using an electrophotographic ferrite carrier core material and a ferrite carrier that match the characteristics of each electrophotographic developing device such as a copying machine.

Claims (3)

A method for evaluating the fluidity of a ferrite carrier core material for an electrophotographic developer comprising ferrite particles,
The accommodation member that accommodates the ferrite particles is given vibration at a predetermined rate of acceleration for a predetermined time, and the weight of the ferrite particles that flow out of the accommodation member due to the applied vibration is measured, and the measured weight of the ferrite particles is obtained. Based on the flow rate data of ferrite particles per unit time, the flow rate data of the ferrite carrier core material for electrophotographic developer is characterized by using the flow rate data to evaluate the properties of the ferrite particles. Method. A method for evaluating the fluidity of a ferrite carrier for an electrophotographic developer in which pores of ferrite particles are filled with a resin and / or coated on the surface with a resin,
The housing member housing the resin-filled and / or resin-coated ferrite particles is given vibration at a predetermined rate of acceleration for a predetermined time, and the weight of the resin-filled and / or resin-coated ferrite particles flowing out of the housing member by the applied vibration. The flow rate data of the resin-filled and / or resin-coated ferrite particles per unit time is obtained based on the measured weight of the resin-filled and / or resin-coated ferrite particles, and the flow rate data is used. A method for evaluating the fluidity of a ferrite carrier for an electrophotographic developer, wherein the characteristics of the resin-filled and / or resin-coated ferrite particles are evaluated. 3. The fluidity evaluation method according to claim 1, wherein before the measurement is performed, vibration is applied to the housing member that contains the powder for a predetermined time while the outlet hole is closed, and the target powder is compressed.

Images