JP4374044B2 - Toner manufacturing method, toner and toner manufacturing apparatus - Google Patents

Description

  The present invention relates to a method for producing toner used in an image forming method in the fields of electrophotography and electrostatic recording.

  In general, a toner is obtained by heat-melting and kneading required materials (for example, dyes, pigment magnetic powder, etc.) in a thermoplastic resin to form a uniform dispersion, and then a pulverization step for pulverizing the cooled kneaded product, and if necessary Through a classification step for classifying the pulverized product, toner particles having a predetermined particle size and particle size distribution are produced. Furthermore, the toner fluidity, charging stability, lubricity, cleaning properties, etc. are improved in order to continue image formation stably in the copying machine development process, transfer process, and cleaning process for removing untransferred toner from the photoreceptor. For the purpose, a toner is manufactured through a process of mixing an external additive such as an inorganic fine powder or an organic fine powder with toner particles.

However, in these steps, coarse particles, fused coarse particles due to mechanical heat generation, van der Waals force, and re-aggregates due to liquid crosslinking are generated, and the coarse particles and re-aggregates are clogged with minute gaps in the developing machine. Or cause various image defects as poorly charged particles. In order to remove coarse particles and re-aggregates, for example, a step of passing through a sieve having an opening of 100 to 2500 μm is performed. As an apparatus having a sieve, for example, there is a multistage gyro shifter, and as a vibration method, there are mechanical vibration and ultrasonic vibration.
By such a method, coarse particles and re-aggregates can be temporarily removed, but at present, there are some points to be improved in the quality of production stable toner. In recent years, the toner has a tendency to reduce the particle size, and the problem is that a new problem has arisen because the opening of the sieve tends to be reduced.

  Conventionally, in a sieve having a mesh size of 100 to 2500 μm, the wire mesh is configured with a wire diameter of 100 μm or more, and the problem of strength in the sieve does not occur even with the cleaning air and vibration generated by the cleaning air. However, since the opening of the toner becomes smaller due to the smaller particle size of the toner, the wire diameter becomes thinner, and the breakage of the sieve is accelerated by the wind pressure of the cleaning air and the vibration strength generated by the cleaning air.

Also, the toner is accelerated by the wind speed created by the cleaning air and collides with the sieve surface. Due to the heat generated by the impact, the toner becomes a molten state and adheres to the wire mesh and grows with time. The deposits are peeled off by vibrations produced by the cleaning air, and at this time, the deposits on the filtration side of the sieve are mixed into the product and cause the above-mentioned problems.
Further, the adhering matter to the sieve causes clogging of the sieve surface, and the differential pressure before and after the sieve increases, so that the load on the sieve increases. This burden is that the sieve opening is reduced, so that the breakage of the sieve is accelerated in terms of strength and the like.

  The state of occurrence of this toner adhering matter varies depending on the toner prescription or the like, but increases rapidly when the air velocity of the air impinging on the screen exceeds 100 m / s.

  Toner adhesion to the sieve is also greatly affected by the humidity of the atmosphere and processing air. Air in the atmosphere flows in at the same time when the toner is put into the sieve. However, when the humidity is high, moisture is deposited on the surface of the toner particles, and sticking to a metal mesh different from melting occurs. This also occurs depending on the humidity of the cleaning air, and is likely to occur even when the difference from the outside air temperature is large.

To date, there are methods described in Patent Document 1 (Japanese Patent Laid-Open No. 9-304968) regarding the method for removing coarse particles and the like of small-diameter toner. Although there are no countermeasures for the condition and cause, there is no description of stable operation and product recovery.
JP-A-9-304968

  In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a method for producing a toner in which aggregates and coarse particles are stably removed and aggregation does not easily occur until the next step. is there.

The above-described problem is that (1) “the toner in the developer contains one or more external additives, the volume average particle size is 5.0 to 11.0 μm, after mixing, the sizes of different air blowing holes as air blowing function towards the sieve surface from the sieve plane passing side (rear) plural also Chi, the air blowing holes is pivoted along the sieve surface, a plurality A method for producing a toner using a sieve in which air blowing holes of the nozzles blow different portions of the sieve surface, wherein the toner is treated with a sieve satisfying the following conditions;
The maximum / minimum ratio of each area of the plurality of air blowing holes is 1.6 or less, sieve opening W 100 μm>W> 20 μm, in the blowing air from the sieve surface passing side (rear) to the sieve surface The amount of water is at or below the atmospheric dew point of -15 ° C., and it consists of a plurality from the sieve surface passing side (rear) toward the sieve surface. The area of the air blowing holes (S1) and the unit time (seconds) of the holes The ratio (S2 / S1) with the passing sieve surface area (S2) satisfies the relationship of (maximum S2 / S1 value) / (minimum S2 / S1 value) ≦ 1.3.
(2) The above-mentioned, wherein the blowing air velocity from a plurality of air blowing holes directed from the sieve surface passage side (rear) to the sieve surface is used at 40 m / s to 100 m / s. (3) “Blowing toward the sieve surface from the powder loading direction side of the sieve (front) and blowing toward the sieve surface from the side passing the washing surface and the sieve surface (rear side)” ) B1 is the time from the start of the rear cleaning air spraying to the start of the front cleaning air spraying by the spraying function in which the cleaning air is sprayed alternately. The time from the start of the front cleaning air spraying to the start of the rear cleaning air spraying. Where B2 is an alternating two-way blowing (B2) and (B1) timing deviation (phase difference) satisfies the following condition: (1) or ( The toner production method according to item 2)
n0.01 sec <time difference (timing deviation) B2 and time difference (timing deviation) B1 <0.1 sec ”, (4)“ in the cleaning air sprayed toward the sieve surface from the powder loading direction side of the sieve (front) The toner production method according to any one of (1) to (3) above, wherein the moisture content of the toner is an atmospheric dew point of −15 ° C. or lower. ”, (5)“ Sieving surface ” The toner production method according to any one of (1) to (4) above, wherein air is blown from at least one portion toward the center of the sieve surface. ”, (6)“ Powder ” The toner production method according to any one of (1) to (5), wherein the humidity of the air sucked together with the powder from the inlet satisfies the following condition.
The amount of moisture in the air is atmospheric dew point -10 ° C. or lower ”, (7)“ Contains a binder resin, a colorant, and a release agent, and any one of the items (1) to (6) ”. Any one of the above-mentioned (1) to (6), wherein the toner has a sieving machine comprising a sieving and a rear cleaning air machine. The toner manufacturing apparatus is used for the toner manufacturing method described above.

  According to the present invention, it is possible to greatly increase the production capacity of the sieving process in the toner manufacturing process, and furthermore, it is possible to significantly reduce the generation of toner aggregates and molten coarse particles after sieving. Is.

Hereinafter, the present invention will be described in detail with reference to the drawings.
In the present invention, the toner particles are mixed with an external additive and then sieved. An example of the sieve used is shown in FIG.
In this sieving machine, the external additive and the mixed toner (1) flow from the inlet (2) and collide with the sieving surface (3). At this time, the fine toner easily passes through the sieving surface (3), but the coarse toner stays on the sieving surface (3) for a while and then passes through the opening. At this time, the toner having a diameter close to the opening size is caught between the sieves to cause clogging. As a breakthrough measure, high-speed air (6) is jetted from the rear cleaning air machine (5) provided in the space (4) behind the sieve surface (3) to the sieve surface and clogged by the pressure and vibration generated therefrom. Remove. At this time, a structure having an opening of about 200 μm to 2 mm behind the sieving mesh can be brought into close contact with the main screen to increase the strength of the main screen. Although it is the shape of the wire mesh used for this sieve, there is no restriction | limiting in particular in plain weave, twill, etc. Similarly, in the material of the sieve, a resin or the like can be used in addition to the metal.

  At this time, the moisture content of the high-speed air (6) ejected from the cleaning air machine (5) to the sieve surface (3) is kept at atmospheric dew point of −15 ° C. or less, thereby reducing the life of the sieve due to generation of aggregates and clogging of the sieve. Decrease can be reduced. Preferably, the amount of moisture is kept at an atmospheric pressure dew point of −20 ° C. or lower, thereby enabling a sieving operation without being affected by disturbance. More preferably, by keeping the water content at atmospheric dew point of −25 ° C. or less, efficient sieving work can be performed while dealing with the increase / decrease of the toner supply amount.

  Similarly, when the toner (1) is caused to flow from the inlet (2) of the sieve, the outside air (14) is sucked at the same time. In an atmosphere where the outside air (14) is not conditioned, the generation of aggregates and clogging of the sieve are likely to occur as described above. Therefore, in this case, reduction of the sieve life due to the generation of aggregates and clogging of the sieve can be reduced by air having an atmospheric pressure dew point of −10 ° C. or less. Preferably, the sieving operation that is not affected by the moisture contained in the toner or the like is made possible by air having a moisture content of atmospheric dew point of -20 ° C. or lower. More preferably, by keeping the water content at atmospheric dew point of −25 ° C. or less, an efficient sieving operation can be performed while accommodating the increase and decrease in the toner supply amount.

  FIG. 2 shows a rear cleaning air machine (5) viewed from the sieve surface (3) and a blowing nozzle (7) for high-speed air (6) on the sieve surface. Although the number of blowing nozzles (7) varies depending on the sieve area, one or a plurality of blowing nozzles (7) are generally provided for one column (8). The normal air speed varies among nozzles due to differences in differential pressure loss due to differences in the air path length to each nozzle, differences in nozzle opening area, differences in opening direction, etc. This is based on the ability to prevent clogging of nozzles with wind speed.

  Therefore, for a nozzle with a high wind speed, a higher wind speed can be obtained by increasing the minimum wind speed portion. For this reason, generation of a melt (10) due to an increase in the collision speed of the toner to the sieve, and a reduction in the sieve life. Fall into. At this time, by setting the ratio of the maximum and minimum values of each blowing nozzle area (9) to 1.6 or less, the low speed region between the blowing nozzles (7) can be reduced, and the wind speed distribution can be made constant. It is effective in reducing the melt inside and improving the sieve life. Preferably, by setting the ratio of the maximum and minimum values of each blowing nozzle area (9) to 1.4 or less, the air speed of the nozzle (7) can be made uniform, which is effective in reducing the melt in the product. . More preferably, by setting the ratio of the maximum and minimum values of each blowing nozzle area (9) to 1.2 or less, it is possible to uniformly reduce the air speed, which is more effective in improving the sieve life.

  Clogging frequently occurs when the energy received per hour is low in the partial area directly received from the cleaning air (6) of the nozzle (7) on the sieve surface (3). Energy is expressed as the product of the square of the wind speed and the area. At this time, when the wind speed of the cleaning air (6) is increased, agglomerates (10) are generated frequently and increase rapidly at 130 m / s or more. Further, at 40 m / s or less, the wind speed at the same level as the wind speed on the sieving surface (3) of the inflowing outside air (14) is low, so the effect of removing the toner adhering matter on the sieving surface (3) is low.

  Therefore, considering the ratio of the opening area (S1) of the blowing nozzle (7) and the area (S2) of the sieving surface (3) through which the rotating blowing nozzle (7) passes in unit time (seconds), the air volume is adjusted. By adjusting and making the relationship between the maximum value and the minimum value of S2 / S1 1.5 or less, the sieve surface (3) can be used effectively, and coarse particles can be removed without clogging. Preferably, by setting the relationship between the maximum value and the minimum value to 1.3 or less, the load on the sieve surface (3) is more equally distributed, which also has an effect on the life of the sieve.

  At this time, the energy received by the sieving surface (3) may be the sum per unit time in the receiving area including the other nozzles (7) in addition to the one nozzle (7).

  In the case of having a circular sieve surface (3) as shown in FIG. 3, the cleaning air (5) is supplied from the shaft center to the rear cleaning air machine (5) and is distributed to each blowing nozzle (7). Each blowing nozzle (7) swirls in the sieve surface (3) by a rotating mechanism (11) provided at the shaft center to apply air removal and vibration to the sieve. In the case of a sieve having such a structure, when the angular velocity is the same, means for adjusting the nozzle opening area (9) to be narrowed according to the distance from the axial center, a method for adjusting the number of blowing nozzles (7), etc. Can be considered.

  In FIG. 4, the sieve which provided the front washing | cleaning air machine (13) in the front space (12) of the sieve surface (3) is shown. The toner supplied to the sieving surface passes finely through the sieving surface (3), but coarse particles and agglomerates cause stagnation and clogging, and are removed or re-entered by the rear cleaning air machine (5). The The front cleaning air machine (13) has a function of assisting the passage speed of the toner sieving surface (3) including the re-entry.

  In order to increase the throughput of the sieve, it is effective to give vibration to the sieve surface. The front cleaning air machine (13) and the rear cleaning air machine (5) have their phases blown so that the amplitude and vibration acceleration can be manipulated. The timing of each cleaning air is the time interval between the front cleaning air (13) and the rear cleaning air (5) and the rear cleaning air (5) and the front cleaning air (13) at an arbitrary point on a certain sieve surface (3). By setting the value from 0.1 sec to 0.01 sec, the vibration of the sieve surface (3) can effectively act and clogging of the sieve surface (3) can be reduced. Preferably, the toner processing amount is increased by changing the time interval between the front cleaning air (13) and the rear cleaning air (5), and the rear cleaning air (5) and the front cleaning air (13) from 0.05 sec to 0.02 sec. Under the above conditions, clogging of the sieve surface (3) can be reduced.

FIG. 5 shows a sieve equipped with a distributed air blowing function (20). The toner that has flowed into the sieving machine does not disperse well due to the air flow and the inertial force, but becomes a biased flow along the path to the sieving surface (3) and reaches the sieving surface (3). This deviation causes a lot of toner adhesion on the sieve surface. Therefore, by providing the air blowing function (20), it is possible to disperse the toner drift before reaching the sieve surface (3) and to remove the adhering matter on the sieve surface, thereby further increasing the processing amount. The spraying position is the outer periphery of the sieve, the angle (22) is 0 plus or minus 20 degrees with respect to the sieve surface (3), and the deviation angle (23) from the shaft center is 0 plus or minus 20 degrees. Can be removed.
As the air source for the air blowing function (20), a supply type using a compressor or the like, and a self-priming type using an in-machine pressure are also effective.

Hereinafter, the present invention will be specifically described with reference to production examples and examples, but this does not limit the present invention in any way.
In addition, all the parts in the following mixing | blending are a weight part.
[Reference Example 1]
Binder resin Polyester resin 100 parts Colorant Carbon black 10 parts Charge control agent Salicylic acid zinc salt 5 parts Release agent Low molecular weight polyethylene 5 parts The above raw materials are thoroughly mixed with a mixer and then kneaded at 120 ° C with a biaxial extruder. Was melt kneaded. The kneaded product is cooled and rolled, coarsely pulverized by a cutter mill, pulverized by a fine pulverizer using a jet stream, and then a swirl type air classifier is used to obtain a weight distribution with a weight average particle size of 7.5 μm and 4 μm or less. 11% toner was obtained. Furthermore, 0.3 part of hydrophobic silica and a specific surface area of 188 m ² / g are mixed with a Henschel mixer with respect to 100 parts of the base colored particles, and further a sieve area of 2830 m ² , an exhaust treatment air volume of 11 m ³ / min, and a throughput of 80 kg per hour. Back washing air was provided with a sieve having an opening of 45 μm at / h, and the sieving step was performed under the conditions described in Table 1. At that time, the screen surface toner adhesion area when the sieving machine is operating and the amount of toner aggregate generated are shown in Table 1. Regarding the measurement of the adhesion area, a CCD camera with a cleaning function was installed inside the sieve, and the area was determined from the image during operation for about 30 minutes. Regarding the wind speed, a hot wire type anemometer MODEL1011 manufactured by Kanomax was used.

[Reference Example 2]
For the toner obtained up to the classification step in Reference Example 1, the ratio of the maximum and minimum spray area of each nozzle of the rear cleaning air that functions as an air spray function from the sieve surface passing side toward the sieve surface is 1.3. Further, the same evaluation as in Reference Example 1 was performed under the conditions described in Table 1. The results are shown in Table 1.

[Reference Example 3]
For the toner obtained up to the classification step in Reference Example 1, the air velocity from the plurality of air blowing holes is used at 80 m / s toward the sieve surface in the production process, and further in Table 1. The same evaluation as in Reference Example 1 was performed under the conditions described. The results are shown in Table 1.

[Example 1]
For the toner obtained up to the classification step in Reference Example 1, the spray area of each nozzle of the rear cleaning air that functions as an air spray from the sieve surface passing side to the sieve surface, and the sieve where the spray surface passes per hour The ratio to the area was set to 1.3 between the maximum and minimum between the nozzles, and the same evaluation as in Reference Example 1 was performed under the conditions described in Table 1. The results are shown in Table 1.

[Example 2]
For the toner obtained up to the classification step in Reference Example 1, on the sieve surface of the sieve having a front washing air function that blows air toward the sieve surface from the powder input direction of the sieve, the back sprayed on the sieve surface from the passing side Evaluation was performed in the same manner as in Reference Example 1 under the conditions described in Table 1 with spraying of cleaning air. The results are shown in Table 1.

[Reference Example 4]
For the toner obtained up to the classification process in Reference Example 1, the time difference between the front cleaning air sprayed on the sieve surface from the sieve powder loading direction and the rear cleaning air sprayed on the sieve surface from the passing side on the sieve surface of the sieve B2 and the time difference B1 between the rear cleaning air blown to the sieve surface from the passing side and the front washing air blown to the sieve surface from the powder feeding direction of the sieve is set to 0.4 sec. Evaluation similar to Example 1 was performed. The results are shown in Table 1.

[Example 3]
For the toner obtained up to the classification step in Reference Example 1, the atmospheric pressure dew point of the front washing air is set to −17 ° C. in the direction opposite to the powder passing direction sprayed from the passing side, and the conditions described in Table 1 Thus, the same evaluation as in Reference Example 1 was performed. The results are shown in Table 1.

[Example 4]
For the toner obtained up to the classification step in Reference Example 1, one air supply port is provided, air is blown from the outside toward the center of the sieve surface, and under the conditions described in Table 1, Reference Example 1 and Similar evaluations were made. The results are shown in Table 1.

[Example 5]
For the toner obtained up to the classification process in Reference Example 1, the humidity of the air sucked together with the powder from the powder inlet is set to the atmospheric pressure dew point of −15 ° C., and the conditions described in Table 1 are satisfied. The same evaluation as in Reference Example 1 was performed. The results are shown in Table 1.

[Comparative Example 1]
The toner obtained up to the classification step in Reference Example 1 was evaluated in the same manner as in Reference Example 1 under the conditions described in Table 1. The results are shown in Table 1.

但し、ＡはＳ２／Ｓ１の最大値と最小値の比であり、Ｂは交番する双方向からの吹付（Ｂ２）及び（Ｂ１）のタイミングのずれ（位相差「秒」）である。

However, A is the ratio between the maximum value and the minimum value of S2 / S1, and B is the timing difference (phase difference “seconds”) between the alternating blowing (B2) and (B1).

It is a figure which shows the sieve installation and back washing | cleaning function of this invention. It is a figure which shows the back washing | cleaning air nozzle of this invention. It is a figure which shows the relationship between the back air nozzle area of this invention, and a sieve area. It is a figure which shows the front washing | cleaning function of this invention. It is a figure which shows the dispersion | distribution air spraying function of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Toner 2 Input port 3 Sieve surface 3.1 Blow area of unit time 3.2 Blow area of unit time 3.3 Blow area of unit time 3.4 Blow area of unit time 4 Space behind sieve surface 5 Back cleaning air Machine 6 High-speed air 7 Blowing nozzle 8 Strut 9 Blowing nozzle area 10 Melt (aggregate)
DESCRIPTION OF SYMBOLS 11 Rotation mechanism 12 Front space 13 Front washing | cleaning air machine 14 Outside air 20 Air blowing function 22 The angle of the air blowing position with respect to a sieve surface 23 The angle of the air blowing position with respect to an axial center

Claims (8)

The toner in the developer contains one or more external additives, the volume average particle size is 5.0 to 11.0 μm, and after mixing with the external additive after adjusting the particle size, the sieve surface passing side (rear) even Chi plurality of different sizes air blowing holes as more air blowing function towards the sieve surface, the air blowing holes is pivoted along the sieve surface, place a plurality of air blowing holes is different Furuimen mutually A method of producing a toner using a sieve for spraying a toner, wherein the toner is treated with a sieve satisfying the following conditions:
The maximum / minimum ratio of each area of the plurality of air blowing holes is 1.6 or less, sieve opening W 100 μm>W> 20 μm, in the blowing air from the sieve surface passing side (rear) to the sieve surface The amount of water is at or below the atmospheric dew point of -15 ° C., and it consists of a plurality from the sieve surface passing side (rear) toward the sieve surface. The area of the air blowing holes (S1) and the unit time (seconds) of the holes The ratio (S2 / S1) with the passing sieve surface area (S2) satisfies the relationship of (maximum S2 / S1 value) / (minimum S2 / S1 value) ≦ 1.3. 2. The toner production according to claim 1, wherein a blowing air velocity from a plurality of air blowing holes directed from the sieve surface passing side (rear) to the sieve surface is used at 40 m / s to 100 m / s. Method. The rear cleaning air blowing is performed by the spraying function in which the cleaning air sprayed from the sieve powder loading direction side toward the sieve surface (front) and the cleaning air sprayed from the sieve surface passing side toward the sieve surface (rear) are alternately sprayed. When the time from the start of spraying to the start of spraying of the front cleaning air is B1, and the time from the start of spraying of the front cleaning air to the start of spraying of the rear cleaning air is B2, The toner manufacturing method according to claim 1, wherein the timing shift (phase difference) of (B1) satisfies the following condition.
0.01 sec <time difference (timing deviation) B2 and time difference (timing deviation) B1 <0.1 sec The amount of water in the cleaning air sprayed from the powder charging direction side of the sieve toward the sieve surface (front) is an atmospheric pressure dew point of -15 ° C or less, according to any one of claims 1 to 3. Toner manufacturing method. 5. The toner manufacturing method according to claim 1, wherein air is blown toward the center of the screen at least at one location from around the screen. 6. The toner manufacturing method according to claim 1, wherein the humidity of the air sucked together with the powder from the powder inlet satisfies the following condition.
Moisture content in air is atmospheric dew point -10 ℃ or less A toner comprising a binder resin, a colorant, and a release agent, wherein the toner is obtained by the toner manufacturing method according to claim 1. 7. A toner manufacturing apparatus used in the toner manufacturing method according to claim 1, wherein the toner manufacturing apparatus has a sieving machine including a sieving machine and a rear cleaning air machine.

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