HK1115739B

HK1115739B - Toner and method for producing the same

Info

Publication number: HK1115739B
Application number: HK08105799.4A
Authority: HK
Inventors: 久保田光治; 渡边昌司; 脇本光太; 牧野信康
Original assignee: 株式会社理光
Priority date: 2006-06-30
Filing date: 2008-05-26
Publication date: 2010-12-17

Description

Toner and method for producing toner

Technical Field

The present invention relates to a method for producing a toner, which is excellent in production efficiency and economic efficiency, and to a toner produced using the method. In this method, in the grinding and classifying step of the toner, more than necessary powdery particles contained in the toner as a product are accurately classified, and the toner having excellent quality characteristics can be stably and easily produced.

Background

Conventionally, methods for grinding and classifying toner (1) one pair of ｃA classifier and ｃA grinder or two or more pairs thereof, (2) ｃA combination of two classifiers and ｃA grinder or the like have been proposed (Japanese patent (JP-B)2851872, Japanese patent application laid-open (JP-B) No. 6-66034, Japanese patent application laid-open (JP-A) Nos. 2003-275685 and 11-15194, and JP-B3748555). For example, jet mill units, known as jet mills, in which a high-pressure gas stream is ejected from a nozzle to contain raw material particles therein, and then the particles collide with each other, or with a wall or other colliding object. In the jet mill, first particles are ground by one or two grinding units and two coarse particle classifying units, and then powdery particles are classified by at least one classifying unit.

Fig. 1 shows an example of a flowchart of the grinding and classifying step of a conventional toner. In the flow shown in fig. 1, a raw material is supplied from a raw material supply portion 1, introduced into a first classifier 2, and then classified into coarse particles and powdery particles. The pulverized particles are recovered in the first cyclone unit 4, while the coarse particles are ground in the first grinder 3 and then once recovered in the first cyclone unit 4. Next, the particles in the first cyclone unit 4 are introduced to the second classifier 6, and then classified into coarse particles and powdery particles. The pulverized particles are recovered in the second cyclone unit 8, while the coarse particles are ground in the second grinder 7 and then recovered in the second cyclone unit 8. The particles in the second cyclone unit 8 are introduced to the third classifier 10 and classified into coarse particles and powdery particles. The coarse particles are recovered as a toner product 11, while the pulverized particles are once recovered in the third cyclone unit 12 and then further classified into coarse particles and pulverized particles in the fourth classifier 13. The powdery particles are recovered in the fourth cyclone unit 14, while the coarse particles are returned to the third classifier 10 through the return pipe 13a, and the classification is repeated until a desired particle size is obtained. The pulverized particles are collected in the fourth cyclone unit 14 as pulverized particles 16. Further, the pulverized particles are collected by the third collector 15 from the upper portion of the third cyclone 12 and the fourth cyclone 14 and the upper portion of the third classifier 10 and the fourth classifier 13. The collected powdery particles are granulated and reused as a kneaded product or directly reused as a kneaded product.

In the flow of the grinding and classifying step shown in fig. 1, the coarse particles classified in the fourth classifier 13 are returned to the third classifier 10, and thus the burden of the third classifier 10 is increased. Further, since the number of particles returned from the fourth classifier 13 is not fixed, the classification density of the third classifier 10 fluctuates, a stable particle diameter distribution cannot be obtained, and the accuracy of classification may be lowered. When an image is formed using the toner obtained by the flow of the grinding and classifying steps as described above, background smear may be generated due to unstable image density and charge amount (chargeamount), and image quality may be degraded due to transfer failure.

Excessive removal of the powder particles results in a reduction in the toner product yield to achieve the desired toner particle size. As a result, the amount of collected powdery particles increases, and the personnel burden (force loading) for reuse increases, and economic disadvantages may be introduced, such as poor production energy efficiency, increased costs, and the generation of excess carbon dioxide.

Disclosure of Invention

An object of the present invention is to provide a method for producing a toner, which is excellent in production efficiency and economic efficiency, in which, in a step of grinding and classifying the toner (finely grinding particles and classifying coarse particles, classifying powdery particles), powdery particles contained in the toner as a product more than necessary are accurately classified in the step, and a toner having excellent quality characteristics can be stably and easily produced, and a toner produced by the method.

The problems described above can be solved as follows:

<1> a method for producing a toner, comprising a milling step and a classifying step, the milling step comprising finely milling particles and classifying coarse particles using at least one mill and cyclone unit; the classifying step includes classifying the powdery particles using at least one classifier and a cyclone unit, wherein any of the powdery particles and other particles classified and returned by the classifier in the classifying step are returned to the cyclone unit in the grinding step.

<2> the method for producing toner according to <1>, wherein at least one grinder, one cyclone unit and one classifier are used in the grinding step.

<3> the method for producing toner according to any one of <1> to <2>, wherein the cyclone unit includes at least one cyclone.

<4> the method for producing toner according to any one of <1> to <3>, wherein the amount of particles in the cyclone unit to which the particles are returned is 15% to 35% of the total volume of the cyclone unit.

<5> the method for producing toner according to any one of <1> to <4>, wherein the particle introducing tube includes a constricted portion in the classifier in the classifying step, and a cross section A1 of the particle introducing tube and a cross section A2 of the constricted portion satisfy the following relationship:

1x(A1/20)≤A2≤10x(A1/20)。

<6> the method for producing toner according to any one of <1> to <5>, wherein a return pipe returning particles to the cyclone unit includes a constricted portion, and a cross section B1 of the return pipe and a cross section B2 of the constricted portion satisfy the following relationship:

1x(B1/20)≤B2≤10x(B1/20)。

<7> the method for producing toner according to any one of <1> to <6>, wherein an upper suction pipe of the cyclone unit to which the particles are returned includes a constricted portion, and a cross section D1 of the upper suction pipe and a cross section D2 of the constricted portion satisfy the following relationship:

1x(D1/20)≤D2≤10x(D1/20)。

<8> the method for producing toner according to any one of <1> to <7>, wherein a cross section C1 of a cylindrical portion of the cyclone unit to which particles are returned and a cross section C2 of the return pipe returning particles to the cyclone unit satisfy the following relationship:

1x(C1/2000)≤C2≤200x(C1/2000)。

<9> the method for producing toner according to any one of <1> to <8>, wherein an insertion angle θ of the return pipe returning particles to the cyclone unit is 30 ° to 150 ° with respect to a vertical line in a longitudinal direction of an insertion position where the return pipe is inserted into the cyclone unit.

<10> the method for producing toner according to any one of <1> to <9>, wherein in the cyclone unit to which the particles are returned, a height L1 from a bottom end of a conical portion to a top end of a cylindrical portion and a height L2 from an insertion position of the return pipe returning the particles to the cyclone unit to a top end of the cylindrical portion of the cyclone unit satisfy the following relationship:

1x(L1/10)≤L2≤9x(L1/10)。

<11> the method for producing a toner according to any one of <1> to <10>, wherein an amount of particles in the cyclone unit to which the particles are returned is adjusted by secondary air (secondary air) from a secondary air pipe (secondary air pipe) disposed on the cyclone unit.

<12> the method for producing toner according to <11>, wherein the position where the secondary air pipe is arranged on the cyclone unit to which the particles are returned is higher than any one of the position where the return pipe is arranged on the cyclone unit and the surface of the particles in the cyclone unit.

<13> the method for producing toner according to any one of <1> to <12>, wherein an amount of particles in the cyclone unit to which the particles are returned is adjusted by a blower flow rate of a collector located above the cyclone unit, and the blower flow rate is 70% or more of a maximum flow rate.

<14> the method for producing toner according to any one of <1> to <13>, wherein the amount of particles in the cyclone unit to which the particles are returned is adjusted by the compressed air pressure from the classifier in the classifying step, and the compressed air pressure is 0.2MPa to 0.6 MPa.

<15>According to<1>To<14>The method of producing a toner described in any one of the above, wherein the amount of the particles in the cyclone unit to which the particles are returned is adjusted by a compressed air flow rate from the classifier in the classifying step, and the compressed air flow rate is 0.5m³Min to 2.5m³/min。

<16> the method for producing toner according to any one of <1> to <15>, wherein the amount of particles in the cyclone unit to which the particles are returned is adjusted by static pressure, and the first static pressure P1 of the upper portion of the cyclone unit is-10 kPa to-30 kPa.

<17> the method for producing toner according to any one of <1> to <16>, wherein the amount of particles in the cyclone unit to which the particles are returned is adjusted by the static pressure, and a pressure difference Δ P (| P1-P2|) between the first static pressure P1 of the upper portion of the cyclone unit and the second static pressure P2 of the lower portion of the cyclone unit is 5kPa or less.

<18> the method for producing toner according to any one of <16> to <17>, wherein the static pressure in the cyclone unit to which particles are returned is adjusted by a secondary air flow rate, and the secondary air flow rate is 300L/min to 1,200L/min.

<19> the method for producing toner according to <18>, wherein the secondary air flow rate in the cyclone unit to which particles are returned is adjusted by an automatic adjusting device.

<20> the method for producing toner according to <19>, wherein the automatic regulating means includes a cleaning means.

<21> the method for producing a toner according to any one of <1> to <20>, wherein the particles returned to the cyclone unit have a mass average particle diameter (mass average particle diameter) of 5.5 μm or less, a number average particle diameter of 4.5 μm or less, and have a content of the powdery particles having a particle diameter of 4.0 μm or less of 40 number average% or more.

<22> the method for producing a toner according to any one of <1> to <21>, wherein the particles collected from the upper portion of the cyclone unit to which the particles are returned have a mass average particle diameter of 4.0 μm or less, a number average particle diameter of 3.0 μm or less, and have a content of powdery particles having a particle diameter of 4.0 μm or less of 70 number average% or more.

<23> the toner produced by the method for producing toner according to any one of <1> to <22 >.

<24> the toner according to <23>, wherein the content of the powdery particles having a particle diameter of 4.0 μm or less is 5 to 25 number average%.

<25> the toner according to any one of <23> to <24>, wherein the toner has a mass average particle diameter of 5.0 μm to 12.0 μm and a number average particle diameter of 4.0 μm to 11.0 μm.

A method for producing a toner, comprising a milling step and a classifying step, wherein the milling step comprises finely milling particles and classifying coarse particles using at least one mill and at least one cyclone unit, and the classifying step comprises classifying pulverized particles using at least one classifier and at least one cyclone unit, wherein any of the pulverized particles and other particles classified and returned by the classifier in the classifying step are returned to the cyclone unit in the milling step. Therefore, at the grinding and classifying step of the toner (finely grinding particles and classifying coarse particles, classifying powdery particles), by giving an additional function to the present situation, it is possible to accurately classify the powdery particles more than necessary, which are contained in the toner as a product, without adding a classifier in this step. The method for producing a toner is thus excellent in production and economic efficiency, and a toner having excellent quality characteristics can be stably and easily produced by using the method.

Drawings

Fig. 1 shows an example of a flow of a conventional milling and classifying step.

FIG. 2 shows an example of the flow of the grinding and classification step in example 1.

FIG. 3 shows an example of the flow of the grinding and classification step in example 3.

Fig. 4 shows an enlarged view of the third classifier and the constriction of fig. 3.

Fig. 5 shows an enlarged view of the fourth classifier and the constriction of fig. 3.

Fig. 6 shows an enlarged view of the constricted portion of fig. 4 and 5.

FIG. 7 shows an example of the flow of the grinding and classification step in example 4.

Fig. 8 shows an enlarged view of the second cyclone unit and the constricted portion of fig. 7.

Fig. 9 shows an enlarged view of the constricted portion of fig. 8.

FIG. 10 shows an example of the flow of the grinding and classification step in example 5.

Fig. 11 shows an enlarged view of the second cyclone unit and the constricted portion of fig. 10.

Fig. 12 shows an enlarged view of the constricted portion of fig. 11.

FIG. 13 shows an example of the flow of the grinding and classifying step in examples 6 to 8.

Fig. 14 shows an enlarged view of the second cyclone unit and the constricted portion of fig. 13.

Fig. 15 shows another enlarged view of the second cyclone unit and the constricted portion in fig. 13.

Fig. 16 shows a further enlarged view of the second cyclone unit and the constricted portion of fig. 13.

FIG. 17 shows an example of the flow of the grinding and classification step in example 9.

FIG. 18 shows an example of the flow of the grinding and classification step in example 10.

FIG. 19 shows an example of the flow of the grinding and classifying step in examples 11 to 14.

Fig. 20 shows an enlarged view of the second cyclone unit and the constricted portion of fig. 19.

Fig. 21 shows another enlarged view of the second cyclone unit and the constricted portion in fig. 19.

Fig. 22 shows a further enlarged view of the second cyclone unit and the constricted portion of fig. 19.

FIG. 23 shows an example of the flow of the grinding and classifying step in example 15.

FIG. 24 shows an example of the flow of the grinding and classifying steps in examples 16 to 17.

Fig. 25 shows an enlarged view of the second cyclone unit and the automatic adjustment device of fig. 24.

Detailed Description

(method for producing toner and toner)

The method for producing the toner of the present invention comprises at least a grinding step and a classifying step, and a melt-kneading step, and may further comprise other steps as necessary.

The milling step is a step of finely milling particles and classifying coarse particles using at least one mill and at least one cyclone unit, and preferably a step of finely milling particles and classifying coarse particles using at least one mill, at least one cyclone unit and at least one classifier.

The classifying step is a step of classifying the powdery particles using at least one classifier and at least one cyclone unit.

In the present invention, any powdery particles and other particles classified and returned in the classification step by the classifier are returned to the cyclone unit in the grinding step.

The toner of the present invention is produced by the method for producing a toner of the present invention.

The details of the toner of the present invention will be explained below by explaining the method of manufacturing the toner of the present invention.

< grinding step and classifying step >

In the grinding step, at least one grinder is used, and preferably two or more grinders are used. The grinding machine is not limited and may be appropriately selected based on the purpose. Examples of the grinding mill include an impact mill and a jet mill.

Examples of impact mills include Turbo mills from Turbo Kogyo co., Ltd and Kryptron from Earth technical co., Ltd.

Examples of jet mills include ultrasonic jet mills PJM-I and IDS of Nippon Pneumatic mfg.co., ltd., and reverse jet mills of Hosokawa Micron ltd., and cross jet mills of Kurimoto, ltd.

At least one classifier, and preferably two or more classifiers, are used in the grinding and classifying step. The classifier is not limited and may be appropriately selected based on the purpose. Examples of classifiers that use swirl flow include the DS classifiers of Nippon aerodynamic mfg.co., Ltd; hosokawa Micron's hybrid (ATP) classifier, Micron classifier, toner classifier, and tandem (tandem) classifier; donalsolec classifier of NIPPON DONALDSON, ltd; and the vortex classifier of Nisshin Engineering inc.

In the milling and classifying step, the cyclone unit has at least one cyclone, and preferably two or more cyclones. Examples thereof include a double-stage cyclone, a three-stage cyclone, and a multi-stage cyclone having four or more cyclones.

The cyclone constituting the cyclone unit includes an upper cylindrical part (also referred to as an outer cylinder) and a lower conical part, and the cyclone to which the particles are returned has a return pipe connected to one side of the conical part.

The cyclone is not limited and may be appropriately selected based on the purpose. Examples thereof include tangential cyclones (tangential cyclones), tangential double cyclones, and lindane type cyclones. In the present invention, "pulverized particles" means pulverized particles having a diameter of 4.0 μm or less, and "other particles" means particles other than the pulverized particles having a diameter of 4.0 μm or less.

In the method of manufacturing a toner of the present invention, the particles returned to the cyclone unit in the milling step preferably have a mass average particle diameter of 5.5 micrometers or less and a number average particle diameter of 4.5 micrometers or less, and the content of the powdery particles having a particle diameter of 4.0 micrometers or less is 40 number average% or more, because the classification accuracy can be improved by removing the powdery particles again and recovering coarse particles.

The particles collected from the upper portion of the cyclone unit to which the particles are returned in the milling step preferably have a mass average particle diameter of 4.0 μm or less and a number average particle diameter of 3.0 μm or less, and the content of powdery particles having a diameter of 4.0 μm or less is 70 number average% or more, because the load of the classifier can be reduced and the accuracy of classification can be improved.

The method of manufacturing the toner of the present invention will be explained below with reference to the drawings. FIG. 2 shows an example of a flow of the grinding and classification steps of the present invention.

In fig. 2, the return pipe 13a returning at least any powdery particles and other particles which are classified in the fourth classifier 13 in the classification step and returned to the third classifier 10 in the classification step in the conventional flow of the grinding and classification step shown in fig. 1 is replaced with a return pipe 13b returning the particles to the second cyclone unit 8 in the grinding step. Therefore, fluctuation of the classification density (solid-to-gas ratio) in the third classifier 10 is reduced as compared with the conventional method, and the accuracy of classification can be stabilized.

In fig. 2, a first collector, a second collector and a third collector are indicated at 5, 9 and 15, respectively.

In the flow of the milling and classifying step shown in fig. 2, the amount of particles in the second cyclone unit 8 to which the particles are returned in the milling step is adjusted to a constant amount.

In terms of improvement in classification performance, the amount of particles in the second cyclone unit 8 to which the particles are returned is preferably adjusted to 15% to 35%, more preferably 20% to 30%, and still more preferably 22% to 28% of the total volume of the cyclone unit. When the amount of particles is less than 15%, the amount of the pulverous particles may be reduced because the pulverous particles are collected in the second collector 9 located above the second cyclone unit 8, and thus, the content of the pulverous particles in the toner product may be increased. When the amount of the particles exceeds 35%, the amount of the pulverized particles collected in the second collector 9 located above the second cyclone unit 8 may be increased, and the content of the pulverized particles in the toner product may be decreased, but the collection rate may be decreased.

Examples of the method for adjusting the amount of particles in the second cyclone unit to which the particles are returned in the milling step include (1) adjustment of the blower flow rate of the collector, (2) adjustment of the compressed air pressure, (3) adjustment by static pressure, (4) adjustment of the flow rate by secondary air (subcodaryair), (5) adjustment of the compressed air flow rate, (6) adjustment of the cross section of the constricted portion of the particle introduction tube in the classifier, (7) adjustment of the cross section of the return tube of the cyclone unit, (8) adjustment of the cross section of the upper suction tube of the cyclone unit, (9) adjustment of the insertion angle of the return tube to the cyclone unit, and (10) adjustment of the insertion position of the return tube to the cyclone unit, as described below.

Next, the flow of the grinding and classifying step shown in fig. 3 is the same as that of the grinding and classifying step shown in fig. 2, except that a constriction 17 is arranged in the particle introduction pipe of the third classifier 10 in the classifying step, and a constriction 18 is arranged in the particle introduction pipe of the fourth classifier 13 in the classifying step.

In the flow of the grinding and classifying step shown in fig. 3, the constriction 17 is arranged in the particle introducing pipe of the third classifier 10 as shown in fig. 4. As shown in fig. 6, the cross section a1 of the particle introducing tube and the cross section a2 of the constricted portion preferably satisfy the following relationship: 1x (A1/20). ltoreq.A 2. ltoreq.10 x (A1/20), and more preferably satisfies the following relationship: 4x (A1/20) is more than or equal to A2 is less than or equal to 6x (A1/20). When the cross section a2 of the constriction is less than 1x (a1/20), the return duct may be blocked and particles cannot be supplied. When the cross section a2 of the constriction is larger than 10x (a1/20), the ability to disperse may be reduced and the yield may not be improved.

As shown in fig. 5, the constriction 18 is arranged in the particle introduction pipe of the fourth classifier 13, and as shown in fig. 6, the cross section a1 of the particle introduction pipe and the cross section a2 of the constriction preferably satisfy the following relationship: 1x (A1/20). ltoreq.A 2. ltoreq.10 x (A1/20), and more preferably satisfies the following relationship: 4x (A1/20) is more than or equal to A2 is less than or equal to 6x (A1/20). When the cross section a2 of the constriction is less than 1x (a1/20), the return duct may be blocked and particles cannot be supplied. When the cross section a2 of the constriction is larger than 10x (a1/20), the ability to disperse may be reduced and the yield may not be improved.

Next, the flow of the milling and classifying step shown in fig. 7 is the same as that of the milling and classifying step shown in fig. 3, except that a constriction 19 is arranged in a return pipe 13b, which return pipe 13b returns the particles from the fourth classifier 13 to the second cyclone unit 8 in the classifying step.

In the flow of the milling and classifying step shown in fig. 7, the constriction 19 is arranged in the return pipe 13b, which return pipe 13b returns the particles to the second cyclone unit 8 as shown in fig. 8. As shown in fig. 9, the cross section B1 of the return pipe and the cross section B2 of the constricted portion preferably satisfy the following relationship: 1x (B1/20). ltoreq.B 2. ltoreq.10 x (B1/20), and more preferably satisfies the following relationship: 4x (B1/20) is more than or equal to B2 is less than or equal to 6x (B1/20). When the cross section B2 of the constriction is less than 1x (B1/20), the return pipe may be clogged and particles cannot be supplied. When the cross section B2 of the constricted portion is larger than 10 × (B1/20), the ability to disperse may be reduced and the yield may not be improved.

Next, the flow of the milling and classifying step shown in fig. 10 is the same as that shown in fig. 7, except that the constriction portion 20 is arranged in the upper suction pipe of the second cyclone unit 8 to which the particles are returned.

In the flow of the milling and classifying step shown in fig. 10, the contraction part 20 is arranged in the upper suction pipe of the second cyclone unit 8 as shown in fig. 11. As shown in fig. 12, the cross section D1 of the return pipe and the cross section D2 of the constricted portion preferably satisfy the following relationship: 1x (D1/20). ltoreq.D 2. ltoreq.10 x (D1/20), and more preferably satisfies the following relationship: 4x (D1/20) is more than or equal to D2 is less than or equal to 6x (D1/20). When the cross section D2 of the constricted portion is less than 1x (D1/20), the upper suction pipe may be clogged and the particles cannot be recovered in the second cyclone unit 8. When the cross section D2 of the constricted portion is larger than 10 × (D1/20), the ability to disperse may be reduced and the yield may not be improved.

Next, the flow of the milling and classifying step shown in fig. 13 is the same as that shown in fig. 7, except that the constriction portion 20 is arranged in the upper suction pipe of the second cyclone unit 8 to which the particles are returned.

In the flow of the milling and classifying step shown in fig. 13, as shown in fig. 14, the cross section of the cylindrical portion of the second cyclone unit 8 is defined as C1, the cross section of the return pipe for returning the particles to the second cyclone unit 8 is defined as C2, and C1 and C2 preferably satisfy the following relationship: 1x (C1/2000). ltoreq.C 2. ltoreq.10 x (C1/2000), and more preferably satisfies the following relationship: 100x (C1/2000) to C2 to 200x (C1/2000). When the cross section C2 of the return pipe is less than 1 × (C1/2000), the return pipe may be clogged and particles cannot be supplied. When the cross section C2 of the return pipe is greater than 200 × (C1/2000), chattering in the return pipe may be large and the content of powdery particles in the product may show large variability.

In the flow of the milling and classifying step shown in fig. 13, as shown in fig. 15, the insertion angle θ of the return pipe returning the particles to the second cyclone unit 8 is preferably 30 ° to 150 °, and more preferably 30 ° to 90 °, with respect to the longitudinal perpendicular P to the insertion position where the return pipe is inserted into the second cyclone unit 8. When the insertion angle θ is less than 30 °, toner particles in the lower portion of the second cyclone unit 8 may sharply increase, and the second collector 9 located above the second cyclone unit 8 may collect toner particles and the yield may be reduced. When the insertion angle θ is larger than 150 °, the second collector 9 located above the second cyclone unit 8 may collect toner particles and the yield may also be reduced.

In the flow of the milling and classifying step shown in fig. 13, as shown in fig. 16, the height from the bottom end of the conical portion to the top end of the cylindrical portion in the second cyclone unit 8 to which the particles are returned is defined as L1, the height from the insertion position where the return pipe is inserted into the second cyclone unit 8 to the top end of the cylindrical portion of the second cyclone unit 8 is defined as L2, and L1 and L2 preferably satisfy the following relationship: 1x (L1/10). ltoreq.L 2. ltoreq.9 x (L1/10), and more preferably satisfies the following relationship: 1x (L1/10) is more than or equal to L2 is more than or equal to 3x (L1/10). When L2 is less than 1x (L1/10), toner particles in the lower portion of the second cyclone unit 8 may sharply increase, and the second collector 9 located above the second cyclone unit 8 may collect toner particles and the yield may be reduced. When L2 is greater than 9x (L1/10), the second collector 9 located above the second cyclone unit 8 may collect toner particles and the yield may be reduced.

The flow of the milling and classifying step shown in fig. 17 is the same as the flow of the milling and classifying step shown in fig. 13, except that the amount of particles in the second cyclone unit 8 to which the particles are returned is adjusted by secondary air (secondary air) from a secondary air pipe (secondary air pipe) disposed on the second cyclone unit 8.

In the flow of the milling and classifying step shown in fig. 17, the amount of particles in the second cyclone unit 8 to which the particles are returned is preferably adjusted by atmospheric pressure secondary air from a secondary air pipe disposed on the cyclone unit 8. The performance of classification can be improved by adjusting the amount of particles by using secondary air.

The flow of the milling and classifying step shown in fig. 18 is the same as that shown in fig. 17, except that the amount of particles in the second cyclone unit 8 to which the particles are returned is adjusted by the blower flow rate in the second collector 9.

In the flow of the milling and classifying step described in fig. 18, the amount of particles in the second cyclone unit 8 to which the particles are returned is preferably adjusted by the blower flow rate in the second collector 9. In terms of improving the classification performance, the blower flow rate in the second collector 9 is preferably adjusted to 70% or more, and more preferably 85% or more of the maximum flow rate. When the blower flow is less than 70% of the maximum flow, the staging performance may be reduced.

Next, the flow of the milling and classifying step shown in fig. 19 is the same as that shown in fig. 18, except that the amount of particles in the second cyclone unit 8 to which the particles are returned is adjusted by the compressed gas.

In the flow of the milling and classifying step shown in fig. 19, the amount of particles in the second cyclone unit 8 to which the particles are returned is preferably adjusted by the compressed air from the fourth classifier 13 in the classifying step. In terms of improving the classification performance, the compressed air pressure (flow rate) is preferably 0.2MPa (megapascal) to 0.6MPa (0.5 m)³Min (cubic meter per minute) to 2.5m³Min), more preferably from 0.4MPa to 0.6MPa (1.5 m)³Min to 2.5m³In/min). When the compressed air pressure (flow velocity) is less than 0.2MPa (0.5 m)³At/min), the return pipe may be blocked and particles cannot be supplied. When the compressed air pressure (flow velocity) 3 is more than 0.6MPa (2.5 m)³Min), the ability to disperse may be reduced and the yield may not be increased.

In the flow of the milling and classifying step shown in fig. 19, as shown in fig. 20, the position E2 is preferably higher than any one of the position E1 and the particle surface E0 of the particles in the second cyclone unit 8 to which the particles are returned, wherein the secondary air pipe of atmospheric pressure at E2 is disposed on the second cyclone unit 8 to which the particles are returned, and the return pipe at E1 is disposed on the second cyclone unit 8. Specifically, in terms of improving the classification performance, E1, E2, and E0 more preferably satisfy the following relationships: e0 ≦ 100mm + E1 ≦ 100mm + E2, and still more preferably satisfies the following relationship: e0 is not less than 50mm, E1 is not less than 50mm and E2.

The surface of the particles in the second cyclone unit means the upper surface of the particles recovered in the second cyclone unit and settled under gravity.

In the flow of the milling and classifying step shown in fig. 19, as shown in fig. 21, the amount of particles in the second cyclone unit 8 to which the particles are returned is adjusted by static pressure, and in terms of improving the classifying performance and yield, if the first static pressure of the upper portion of the second cyclone unit 8, such as the cylindrical portion of the cyclone, is defined as P1, the first static pressure P1 is preferably-10 kPa (kilopascal) to-30 kPa, and more preferably-15 kPa to-25 kPa. When the first static pressure P1 is greater than-10 kPa, the swirling force in the second cyclone unit may be reduced and the dispersing ability may be reduced. When the first static pressure P1 is less than-30 kPa, the dispersion ability may be increased, but the yield may be decreased.

In the flow of the milling and classifying step shown in fig. 19, as shown in fig. 22, the amount of particles in the second cyclone unit 8 to which the particles are returned is adjusted by static pressure, and in terms of improving the classifying performance, if the first static pressure of the upper portion of the second cyclone unit 8, for example, the cylindrical portion of the cyclone, is defined as P1 and the second static pressure of the lower portion of the second cyclone unit 8, for example, the conical portion of the cyclone, is defined as P2, the pressure difference Δ P (| P1-P2|) is preferably 5kPa or less, and more preferably 1kPa or less.

The flow of the milling and classifying step shown in fig. 23 is the same as that shown in fig. 19, except that the static pressure in the second cyclone unit 8 to which the particles are returned is adjusted by the secondary air flow rate.

In the flow of the milling and classifying step shown in fig. 23, the static pressure in the second cyclone unit 8 to which the particles are returned is adjusted by the secondary air flow rate, and the secondary air flow rate is preferably 300L/min to 1,200L/min, and more preferably 300L/min to 800L/min. When the secondary air flow rate exceeds 1,200L/min, the classification performance may be lowered.

The flow of the milling and classifying step shown in fig. 24 is the same as that shown in fig. 19, except that the flow rate of the secondary air in the second cyclone unit 8 to which the particles are returned is adjusted by the automatic adjusting device 21.

In the flow of the milling and classifying step shown in fig. 24, the classifying performance can be improved by adjusting the secondary air flow rate in the second cyclone unit 8 to which the particles are returned using the automatic adjusting device 21.

The automatic adjusting means is not limited and may be appropriately selected based on the purpose. For example, a unit configured to convert a pressure difference Δ P generated in the pipe arrangement into an electrical signal and to adjust the valve by the controller.

In the flow of the grinding and classifying step shown in fig. 24, the automatic adjusting device 21 is preferably equipped with a cleaning device as shown in fig. 25. The cleaning device is not limited and may be appropriately selected based on the purpose. For example, a unit configured to detect a pressure difference Δ P generated in the pipe arrangement at regular time intervals and to blow back in the pipe arrangement.

< melt-kneading step >

Examples of the other steps include a melt-kneading step. In the melt-kneading step, the toner materials are mixed and the mixture is placed in a melt kneader and melt-kneaded. As the melt-kneader, it is possible to use a single-shaft or twin-shaft continuous kneader, and a batch type kneader using a roll mill. Examples of the melt-kneader include a KTK type biaxial extruder manufactured by Kobe Steel, ltd.; a TEM type extruder manufactured by Toshiba Machine co., ltd.; a biaxial extruder made of KCK; a PCM type twin-screw extruder manufactured by Ikegai, ltd.; and Co-kneader manufactured by Buss. These melt kneaders are preferably used under appropriate conditions not to cause separation of molecular chains of the binder resin. Specifically, when the melt-kneading temperature excessively exceeds the softening point of the binder resin, the molecular chains are strongly separated. When the melt-kneading temperature may be excessively lower than the softening point of the binder resin, the dispersion may not proceed.

The toner material includes at least a binder resin, a colorant, a releasing agent, and a charge control agent, and further contains other components as necessary.

Binder resin-

Examples of the binder resin include homopolymers and copolymers, and specific examples thereof include styrenes such as styrene and chlorostyrene; mono-olefins such as ethylene, propylene, butylene, isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate; α -methylene aliphatic monocarboxylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone.

Examples of typical binder resins include polystyrene resins, polyester resins, styrene-acrylate copolymers, styrene-alkyl methacrylate copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, styrene-maleic anhydride copolymers, polyethylene resins, and polypropylene resins. These may be used alone or in combination.

Colorants-

The colorant is not particularly limited and may be appropriately selected from known dyes and pigments based on the purpose. Examples include carbon black, nigrosine dyes, black antimony powder, naphthol Yellow S, Hansa Yellow (10G, 5G, G), cadmium Yellow, Yellow iron oxide, Yellow ocher, chrome Yellow, titanium Yellow, Polyazo Yellow (Polyazo Yellow), oil Yellow, Hansa Yellow (GR, A, RN, R), pigment Yellow L, benzidine Yellow (G, GR), permanent Yellow (NCG), Fast Yellow sulfide (VULCAN FASTYLOW) (5G, R), tartrazine lake, quinoline Yellow lake, anthrene Yellow BGL, isoindolinone Yellow, red lead powder, red lead, red mercuric oxide, antimony red, permanent red 4R, cadmium red, pyrosine, parachlor o-nitroaniline red, lithofast Scarlet G (Lithol ScarletG), Brilliant Scarlet (Brilliant Fast Scarlet), Brilliant Carmine BS (Brilliant Carmine BS), Brilliant Fast red (FRF 4F), Brilliant Scarlet RH, Brilliant Scarlet VD), Brilliant Fast red RH, Brilliant Scarlet B RH, Brilliant Fast red RH, and Brilliant Scarlet, Lithol rubine GX, permanent red F5R, bright magenta 6B, pigment scarlet 3B, purplish red 5B, toluidine purplish red, permanent purplish red F2K, solar purplish red BL, purplish red 10B, BON purplish red (BON MAROON LIGHT), BON intermediate purplish red (BONMAROON MEDIUM), eosine lake, rhodamine lake B, rhodamine lake Y, alizarin lake, thioindigo B, thioindigo carmine, oil red, quinacridone red, pyrazolone red, polyazo red, chrome vermilion, benzidine orange, perynone orange, oil orange, cobalt blue, cyan blue, basic blue lake, malachite blue lake, Vedoria blue lake, metallo-free phthalocyanine blue, fast blue, indanthrene blue (RS and BC), indigo blue, manganese blue, anthraquinone, cyanine blue, fast blue, violet B, violet, violet green, violet, yellow, violet, emerald Green, pigment Green B, naphthol Green B, Green Gold (Green Gold), acid Green lake, malachite Green lake, phthalocyanine Green, anthraquinone Green, titanium dioxide, zinc white, lithopone, and combinations thereof. These may be used alone or in combination.

The color of the colorant is not particularly limited and may be appropriately selected based on the purpose, for example, a black pigment and a color pigment. These may be used alone or in combination.

Examples of black colorants include carbon black (c.i. pigment black 7) such as furnace black, lamp black, acetylene black, and channel black; metals such as copper, iron (c.i. pigment black 11), and titanium white, and organic pigments such as aniline black (c.i. pigment black 1). Examples of magenta colorants include c.i. pigment red 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48:1, 49, 50, 51, 52, 53, 51:1, 54, 55, 57:1, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 163, 177, 179, 202, 206, 207, 209, 211; c.i. pigment violet 19; c.i. vat red 1,2, 10, 13, 15, 23, 29, 35.

Examples of cyan colored pigments include c.i. pigment blue 2, 3, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17, 60; c.i. vat blue 6; c.i. acid blue 45, a copper phthalocyanine pigment having a phthalocyanine skeleton substituted with 1-5 phthalimidomethyl, green 7 and green 36.

Examples of yellow colored pigments include c.i. pigment yellow 0-16, 1,2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 55, 65, 73, 74, 83, 97, 110, 151, 154, 180; c.i. vat yellow 1, 3, 20 and orange 36.

The content of the colorant in the toner is not limited and may be appropriately selected based on the purpose. Preferably 1 to 15% by mass, and more preferably 3 to 10% by mass. When the content is less than 1% by mass, the coloring power of the toner may be reduced. When the content is more than 15% by mass, the pigment will not be dispersed in the toner, the coloring power may be reduced, and the electrical characteristics of the toner may be reduced.

The colorant may also be used as a master batch in combination with the resin. The resin is not limited and may be selected from known resins based on the use. Examples thereof include polymers of styrene and substitution products thereof, styrene copolymers, polymethyl methacrylate resins, polybutyl methacrylate resins, polyvinyl chloride resins, polyvinyl acetate resins, polyethylene resins, polypropylene resins, polyester resins, epoxy polyol resins (epoxy polyol resins), polyurethane resins, polyamide resins, polyvinyl butyral resins, polyacrylic acid resins, rosins, modified rosins, terpene resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, and paraffins. These may be used alone or in combination.

Examples of the polymer of styrene and substitution products include polyester resins, polystyrene resins, poly (p-chlorostyrene) resins and polymethylstyrene resins. Examples of the styrene copolymer include styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-alpha-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl-methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methyl ketone copolymer, styrene-butadiene copolymer, and styrene-acrylonitrile-indene copolymers, styrene-maleic acid copolymers, and styrene-maleic acid ester copolymers.

The master batch can be prepared by mixing or kneading the resin for master batch and the colorant under high shear force. In this step, an organic solvent is preferably used for higher interaction between the colorant and the resin. Further, it is preferable to employ a "flushing process" in which an aqueous slurry containing a colorant and water is mixed or kneaded with a resin and an organic solvent to thereby transfer the colorant to the resin component, and then the water and the organic solvent are removed. According to the method, the wet colorant mass can be used without drying. High shear bulk devices such as three-roll mills may be preferred for mixing or kneading.

Anti-sticking agents

The releasing agent is not limited and may be appropriately selected from known releasing agents based on the use. Examples thereof include waxes such as carbonyl group-containing waxes, polyolefin waxes and long-chain hydrocarbons. These may be used alone or in combination.

Examples of carbonyl-containing waxes include polyalkoxylates, polyalkoxylate amides, polyalkylamides, and dialkyl ketones. Examples of the polyalkyl alcohol ester include carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerol tribehenate, and 1, 18-octadecanediol distearate. Examples of the polyalkanol ester include tristearyl trimellitate and distearyl maleate. Examples of the polyalkanoic acid amide include behenamide. Examples of polyalkylamides include tristearylamide trimellitate (tristearylamide trimetallite). Examples of dialkyl ketones include distearyl ketone. Of these carbonyl-containing waxes, the polyalkanol esters are preferably used.

Examples of the polyolefin wax include polyethylene wax and polypropylene wax.

Examples of long chain hydrocarbons include paraffin wax and Sasol wax.

The content of the releasing agent in the toner is not particularly limited and may be appropriately selected according to the purpose. It is preferably 0% by mass to 40% by mass, more preferably 3% by mass to 30% by mass. When the content is more than 40% by mass, the fluidity of the toner may be adversely affected.

Charge control agent-

The charge control agent is not particularly limited and may be selected from known charge control agents according to purposes. The charge control agent is preferably prepared from a material having a color close to transparent and/or white because a colored material can change the color tone. Examples thereof include triphenylmethane dyes, molybdic acid chelate pigments, rhodamine dyes, alkoxyamines, quaternary ammonium salts such as fluorine-modified quaternary ammonium salts, alkylamides, elemental phosphorus or compounds thereof, elemental tungsten or compounds thereof, fluorine-containing active agents, metal salts of salicylic acid, and metal salts of salicylic acid derivatives. These may be used alone or in combination.

Examples of the charge control agent include commercially available products: quaternary ammonium salts with the trade name Bontron p-51, alpha-naphtholic acid metal complexes with Bontron E-82, salicylic acid metal complexes with Bontron E-84, phenol condensates with Bontron E-89 (origin chemical industries, Ltd.); quaternary ammonium molybdenum metal complexes of TP-302 and TP-415 (Hodogaya chemical Co.); quaternary ammonium salts of Copy Charge PSY VP2038, triphenylmethane derivatives of Copy Blue PR, and quaternary ammonium salts of Copy Charge NEG VP2036 and Copy Charge NXVP434 (Hoechst Ltd.); boron complexes of LRA-901 and LR-147 (Japan Carlit Co., Ltd.); quinacridone, azo pigments; and other high molecular weight compounds having functional groups such as sulfonic acid groups, carboxyl groups, and quaternary ammonium salts.

The charge control agent may be dissolved and/or dispersed in the toner material after melt kneading with the master batch. The charge control agent may also be added directly with the toner material when dissolved and/or dispersed in an organic solvent. In addition, the charge control agent may be added to the surface of the toner particles after the toner particles are prepared.

The content of the charge control agent in the toner is determined depending on the kind of the binder resin, the presence or absence of the additive used therefor, and the method of producing the toner including the dispersion method, and the content is not specifically defined. The content of the charge control agent is preferably 0.1 part by mass to 10 parts by mass, and more preferably 0.2 part by mass to 5 parts by mass, based on 100 parts by mass of the binder resin. When the content of the charge control agent is less than 0.1 parts by mass, the charge may not be properly controlled. When the content of the charge control agent is more than 10 parts by mass, the effect of the charge control agent is weakened and the electrostatic attraction to the developing roller is increased due to the excessive charging ability of the toner, which may result in a decrease in the fluidity of the developer or the image density.

Other ingredients-

The other components are not particularly limited and may be appropriately selected according to the purpose. Examples thereof include external additives (external additives), flow improvers, cleaning improvers (cleaning improvers), magnetic materials and metal soaps.

The external additive is not limited and may be appropriately selected from known external additives according to purposes. Examples thereof include silica fine particles, hydrophobized silica fine particles, fatty acid metal salts such as zinc stearate, aluminum stearate; metal oxides such as titanium oxide, aluminum oxide, tin oxide, antimony oxide, and hydrophobized products thereof; and a fluoropolymer. Of these, hydrophobized silica fine particles, titania particles, and hydrophobized titania particles are preferable.

The toner of the present invention is produced by a method for producing the toner of the present invention.

The content of the powdery particles having a particle diameter of 4.0 μm or less in the toner is preferably 5 to 25 number average%, more preferably 18 to 22 number average%. When the content of the powdery particles having a particle diameter of 4.0 μm or less is less than 5 number average%, the powdery particles are excessively removed and the yield may be lowered. When the content of the powdery particles having a particle diameter of 4.0 μm or less is more than 25 number average%, background smear (background) may occur when the toner is used for copying.

The mass average particle diameter of the toner is preferably 5.0 μm to 12.0. mu.m, more preferably 6.5 μm to 10.0. mu.m. The number average particle diameter is preferably 4.0 μm to 11.0. mu.m, more preferably 5.5 μm to 9.0. mu.m.

The particle size distribution and the average particle size are measured by a particle size analyzer "Coulter multisizer III", for example, from Coulter electronics ltd.

According to the present invention, the conventional problems can be solved, and it is possible to provide a method for producing a toner, and a toner produced by a method excellent in productivity and economic efficiency, in which in a grinding and classifying step (finely grinding particles and classifying coarse particles, classifying powdery particles) of a toner, more powdery particles than necessary contained in the toner as a product are accurately classified by giving an additional function to the present situation without adding a classifier in the step, and a toner having excellent quality characteristics can be stably and easily produced by using the method.

Examples

Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

Example 1

Preparation of powdered ink material

A toner material composed of 50% by mass of a polyester-based resin, 30% by mass of a styrene-acrylate copolymer, 15% by mass of carbon black, 4.5% by mass of wax, and 0.5% by mass of a charge control agent was melt-kneaded, cooled, solidified, and then coarsely ground with a hammer mill to prepare a toner raw material.

Grinding and classifying

The toner raw material was ground and classified according to the flow of the grinding and classification step shown in fig. 2. In the flow shown in fig. 2, any powdery particles and other particles are returned from the fourth classifier 13 in the classifying step to the second cyclone unit 8 in the grinding step through the return pipe 13 b. In the second cyclone unit 8, a double-stage cyclone is used.

According to the flow of the grinding and classifying step shown in fig. 2, the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured as described below every 30 minutes. The toner had a number average particle diameter of 7.0 μm, a mass average particle diameter of 9.0 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 24.0 number average% (standard deviation σ ═ 2.4), and a yield of 87.0%.

Measurement of particle size and particle size distribution

The particle diameter and the particle diameter distribution were measured using a Coulter Counter method using a Coulter Multisizer III (manufactured by Beckman Coulter Inc.) as a measuring device for the toner particle distribution as follows:

first, as a dispersant, 0.1ml to 5ml of a surfactant (alkylbenzene sulfonate) was added to 100ml to 150ml of an electrolytic solution. The electrolytic solution was a1 mass% NaCl aqueous solution prepared using primary sodium chloride (ISOTON-II, Beckmann CoulterInc.). Subsequently, 2mg to 20mg of the sample to be tested was further added. The sample suspension is sonicated using an sonicator for 1 minute to 3 minutes. The mass and the number of toner particles were measured using a 100 μm pore size measuring instrument to obtain the mass distribution and the number distribution thereof, from which the mass average particle diameter, the number average particle diameter, and the content of the powdery particles having a particle diameter of 4.0 μm or less of the toner were obtained.

For the channels, 13 different channels were used-from 2.00 μm or more to 2.52 μm or less; from 2.52 μm or more to 3.17 μm or less; from 3.17 μm or more to 4.00 μm or less; from 4.00 μm or more to 5.04 μm or less; from 5.04 μm or more to 6.35 μm or less; from 6.35 μm or more to 8.00 μm or less; from 8.00 μm or more to 10.08 μm or less; from 10.08 μm or more to 12.70 μm or less; from 12.70 μm or more to 16.00 μm or less; from 16.00 μm or more to 20.20 μm or less; from 20.20 μm or more to 25.40 μm or less; from 25.40 μm or more to 32.00 μm or less; and from 32.00 μm or more to 40.30 μm or less, particles having a diameter of 2.00 μm or more to 40.30 μm or less are targeted.

Comparative example 1

The same toner raw materials as in example 1 were ground and classified according to the conventional flow of the grinding and classifying step shown in fig. 1, to produce a toner.

In the flow shown in fig. 1, any powdery particles and other particles from the fourth classifier 13 in the classifying step are returned to the third classifier 10 in the classifying step through the return pipe 13 a.

According to the flow of the grinding and classifying step shown in fig. 1, the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 6.5 μm, a mass average particle diameter of 8.8 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 26.0 number average% (standard deviation σ ═ 3.0), and a yield of 85.0%.

Example 2

According to the flow of the grinding and classifying step shown in fig. 2, the same toner raw materials as in example 1 were ground and classified to produce toners as follows:

in example 2, the amount of particles in the second cyclone unit 8 to which the particles were returned was adjusted to a constant value in the range of 15% to 35% of the total volume of the second cyclone unit, and then the particles were milled and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.2 μm, a mass average particle diameter of 9.0 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 24.0 number average% (standard deviation σ ═ 2.0), and a yield of 88.0%.

Alternatively, the amount of particles in the second cyclone unit 8 to which the particles are returned is adjusted to a constant value in the range of 20% to 30% of the total volume of the second cyclone unit, and then the particles are ground and classified for 5 hours, and the particle diameter distribution of the particles are measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.2 μm, a mass average particle diameter of 9.0 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 24.0 number average% (standard deviation σ ═ 2.0), and a yield of 88.0%.

Alternatively, the amount of particles in the second cyclone unit 8 to which the particles are returned is adjusted to a constant value in the range of 22% to 28% of the total volume of the second cyclone unit, and then the particles are ground and classified. The toner had a number average particle diameter of 7.3 μm, a mass average particle diameter of 9.0 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 24.0 number average% (standard deviation σ ═ 1.8), and a yield of 88.5%.

Example 3

According to the flow of the grinding and classifying step shown in fig. 3, the same toner raw materials as in example 1 were ground and classified to produce toners as follows:

the flow of the grinding and classifying step shown in fig. 3 is the same as that of the grinding and classifying step shown in fig. 2, except that the constricted portion 17 shown in fig. 6 is arranged in the particle introducing pipe of the third classifier 10 shown in fig. 4, and the constricted portion 18 shown in fig. 6 is arranged in the particle introducing pipe of the fourth classifier 13 shown in fig. 5.

The cross section a2 of the constricted portion was set at a constant value in the range from 1x (a1/20) to 10x (a1/20), and then the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.4 μm, a mass average particle diameter of 9.05 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 22.0 number average% (standard deviation σ ═ 1.6), and a yield of 89.5%.

Example 4

According to the flow of the grinding and classifying step shown in fig. 7, the same toner raw materials as in example 1 were ground and classified to produce toners as follows:

the flow of the milling and classifying step shown in fig. 7 is the same as that of the milling and classifying step shown in fig. 3, except that the constriction 19 is arranged in a return pipe which returns the particles to the second cyclone unit 8 in the flow of the milling and classifying step shown in fig. 3.

In the flow of the milling and classifying step shown in fig. 7, the constricted portion 19 was arranged in the return pipe of the second cyclone unit 8 as shown in fig. 8, the cross section of the constricted portion 19 or B2 shown in fig. 9 was set at a constant value in the range from 1x (B1/20) to 10x (B1/20), then the particles were milled and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.4 μm, a mass average particle diameter of 9.05 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 22.0 number average% (standard deviation σ ═ 1.4), and a yield of 89.5%.

Alternatively, the cross section B2 of the constricted portion was set to 10 × (B1/20), and then the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.4 μm, a mass average particle diameter of 9.0 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 22.0 number average% (standard deviation σ ═ 1.4), and a yield of 89.5%.

Example 5

According to the flow of the grinding and classifying step shown in fig. 10, the same toner raw materials as in example 1 were ground and classified to produce toners as follows:

the flow of the milling and classifying step shown in fig. 10 is the same as that shown in fig. 7, except that a constriction 20 is arranged in the upper suction pipe of the second cyclone unit 8 to which the particles are returned.

In the flow of the milling and classifying step shown in fig. 10, the constricted portion 20 was arranged in the upper suction pipe of the second cyclone unit 8 as shown in fig. 11, the cross section of the constricted portion 20 or D2 shown in fig. 12 was set at a constant value in the range from 10x (D1/20) to 1x (D1/20), then the particles were milled and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.4 μm, a mass average particle diameter of 9.0 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 22.0 number average% (standard deviation σ ═ 1.4), and a yield of 90.0%.

Example 6

According to the flow of the grinding and classifying step shown in fig. 13, the same toner raw materials as in example 1 were ground and classified to produce toners as follows:

the flow of the milling and classifying step shown in fig. 13 is the same as that shown in fig. 7, except that a constriction 20 is arranged in the upper suction pipe of the second cyclone unit 8.

In the flow of the milling and classifying step shown in fig. 13, as shown in fig. 14, the cross section of the return pipe of the second cyclone unit 8 to which the particles are returned or C2 was set to 200x (C1/2000) for the cross section of the cylindrical part of the second cyclone unit 8 or C1, and then the particles were milled and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.4 μm, a mass average particle diameter of 9.0 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 22.0 number average% (standard deviation σ ═ 1.2), and a yield of 90.0%.

Alternatively, the cross section C2 of the return pipe was set to 1x (C1/2000) for the cross section C1 of the cylindrical portion of the second cyclone unit 8, and then the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.4 μm, a mass average particle diameter of 9.0 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 22.0 number average% (standard deviation σ ═ 1.2), and a yield of 90.0%.

Example 7

in the flow of the milling and classifying step shown in fig. 13, as shown in fig. 15, the insertion angle of the longitudinal perpendicular P to the insertion position of the return pipe returning the particles to the second cyclone unit 8 was adjusted to a constant value in the range from 30 ° to 90 °, and then the particles were milled and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.4 μm, a mass average particle diameter of 9.08 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 21.5 number average% (standard deviation σ ═ 1.2), and a yield of 90.0%.

Alternatively, the insertion angle was set to 150 °, then the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.3 μm, a mass average particle diameter of 9.1 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 23.0 number average% (standard deviation σ ═ 1.2), and a yield of 89.5%.

Example 8

in the flow of the milling and classifying step shown in fig. 13, as shown in fig. 16, the height from the bottom end of the conical portion to the top end of the cylindrical portion in the second cyclone unit 8 to which the particles are returned is defined as L1, the height from the insertion position of the return pipe returning the particles to the second cyclone unit 8 to the top end of the cylindrical portion of the second cyclone unit 8 is defined as L2, and the following relationship is preferably satisfied: l1 and L2 at 1x (L1/10). ltoreq.L 2. ltoreq.3 x (L1/10) were held at a certain value, and then the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.45 μm, a mass average particle diameter of 9.08 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 21.0 number average% (standard deviation σ ═ 1.2), and a yield of 90.0%.

Alternatively, the position L2 of the return pipe was set to 9 × (L1/10), and then the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.3 μm, a mass average particle diameter of 9.05 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 22.0 number average% (standard deviation σ ═ 1.2), and a yield of 89.0%.

Example 9

According to the flow of the grinding and classifying step shown in fig. 17, the same toner raw materials as in example 1 were ground and classified to produce toners as follows:

the flow of the milling and classifying step shown in fig. 17 is the same as that shown in fig. 13, except that the secondary air pipe is disposed above the second cyclone unit 8 to which the particles are returned.

In the flow of the milling and classifying step shown in fig. 17, in order to adjust the amount of particles in the second cyclone unit 8, the particles were milled and classified for 5 hours using secondary air of atmospheric pressure, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.5 μm, a mass average particle diameter of 9.0 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 20.0 number average% (standard deviation σ ═ 1.2), and a yield of 90.0%.

Example 10

According to the flow of the grinding and classifying step shown in fig. 18, the same toner raw materials as in example 1 were ground and classified to produce toners as follows:

in the flow of the milling and classifying step shown in fig. 18, in order to adjust the amount of particles in the second cyclone unit 8 to which the particles were returned, the blower flow rate of the second collector 9 was adjusted to 85% of the maximum flow rate, held at a certain value, and then the particles were milled and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.5 μm, a mass average particle diameter of 9.0 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 21.0 number average% (standard deviation σ ═ 1.2), and a yield of 90.5%.

The blower flow rate of the second collector 9 was adjusted to 70% of the maximum flow rate, maintained at a certain value, and then the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.4 μm, a mass average particle diameter of 9.1 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 24.0 number average% (standard deviation σ ═ 1.2), and a yield of 89.0%.

Example 11

According to the flow of the grinding and classifying step shown in fig. 19, the same toner raw materials as in example 1 were ground and classified to produce toners as follows:

the flow of the milling and classifying step shown in fig. 19 is the same as that of the milling and classifying step shown in fig. 18 except that compressed air is added from the fourth classifier 13 to the second cyclone unit 8 to which the particles are returned.

The flow of the grinding and classification steps shown in FIG. 19In order to adjust (classify) the amount of particles in the second cyclone unit 8 to which the particles are returned, the compressed air pressure (flow rate) of the fourth classifier 13 is adjusted to be from 0.4MPa to 0.6MPa (1.5 m)³Min to 2.5m³Min), then the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.5 μm, a mass average particle diameter of 9.1 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 20.5 number average% (standard deviation σ ═ 1.2), and a yield of 90.5%.

Alternatively, the compressed air pressure (flow rate) is adjusted to 0.2MPa (0.5 m)³Min), held at a certain value, and then the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.5 μm, a mass average particle diameter of 9.1 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 20.5 number average% (standard deviation σ ═ 1.4), and a yield of 90.5%.

Example 12

in the flow of the milling and classifying step shown in fig. 19, as shown in fig. 20, the positional relationship between the position E2 where the secondary air pipe is arranged above the second cyclone unit 8 to which the particles are returned, the position E1 where the return pipe is arranged above the second cyclone unit 8, and the particle surface position E0 of the particles in the second cyclone unit 8 is adjusted to satisfy the following range: e0. gtoreq.E 1. gtoreq.E 2, held at a certain value, and then the granules were ground and classified for 5 hours, and the particle diameter distribution of the granules were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.3 μm, a mass average particle diameter of 9.1 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 24.0 number average% (standard deviation σ ═ 2.0), and a yield of 88.5%.

Alternatively, the positional relationship is adjusted to satisfy the following range: e0. ltoreq.50 mm + E1. ltoreq.50 mm + E2, held at a certain value, and then the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.5 μm, a mass average particle diameter of 9.1 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 20.5 number average% (standard deviation σ ═ 1.2), and a yield of 90.5%.

Example 13

in the flow of the milling and classifying step shown in fig. 19, as shown in fig. 21, the first static pressure P1 in the second cyclone unit 8 to which the particles were returned was adjusted to a constant value in the range from-10 kPa to-30 kPa, and then the particles were milled and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.55 μm, a mass average particle diameter of 9.1 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 20.0 number average% (standard deviation σ ═ 1.2), and a yield of 90.5%.

Alternatively, the first static pressure P1 in the second cyclone unit 8 was adjusted to-30 kPa, held at a certain value, and then the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.5 μm, a mass average particle diameter of 9.2 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 18.0 number average% (standard deviation σ ═ 1.2), and a yield of 87.5%.

Example 14

in the flow of the milling and classifying step shown in fig. 19, as shown in fig. 22, the pressure difference Δ P (| P1-P2|) in the second cyclone unit 8 to which the particles were returned was adjusted to 1kPa, held at a certain value, and then the particles were milled and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.55 μm, a mass average particle diameter of 9.1 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 19.5 number average% (standard deviation σ ═ 1.2), and a yield of 90.5%.

Alternatively, the pressure difference Δ P (| P1-P2|) in the second cyclone unit 8 was adjusted to 5kPa, held at a certain value, and then the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.5 μm, a mass average particle diameter of 9.2 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 17.5 number average% (standard deviation σ ═ 1.2), and a yield of 87.5%.

Example 15

According to the flow of the grinding and classifying step shown in fig. 23, the same toner raw materials as in example 1 were ground and classified to produce toners as follows:

In the flow of the milling and classifying step shown in fig. 23, the static pressure in the second cyclone unit 8 to which the particles were returned was adjusted to a secondary air flow rate of 300L/min, maintained at a certain value, and then the particles were milled and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.55 μm, a mass average particle diameter of 9.1 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 19.5 number average% (standard deviation σ ═ 1.2), and a yield of 90.5%.

Alternatively, the static pressure in the second cyclone unit 8 was adjusted to a secondary air flow rate of 400L/min, maintained at a certain value, and then the particles were milled and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.6 μm, a mass average particle diameter of 9.1 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 18.5 number average% (standard deviation σ ═ 1.2), and a yield of 91.0%.

Further, the static pressure in the second cyclone unit 8 was adjusted to a secondary air flow rate of 1,200L/min, maintained at a certain value, and then the particles were milled and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.55 μm, a mass average particle diameter of 9.1 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 18.5 number average% (standard deviation σ ═ 1.2), and a yield of 90.0%.

Example 16

According to the flow of the grinding and classifying step shown in fig. 24, the same toner raw materials as in example 1 were ground and classified to produce toners as follows:

the flow of the milling and classifying step shown in fig. 24 is the same as that shown in fig. 19, except that the flow rate of the secondary air in the second cyclone unit 8 to which the particles are returned is adjusted by an automatic adjusting device.

In the flow of the milling and classifying step shown in fig. 24, the secondary air flow rate in the second cyclone unit 8 was adjusted by an automatic adjusting device (a device configured to automatically adjust the opening of a control valve) 21, and then the particles were milled and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.65 μm, a mass average particle diameter of 9.1 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 18.5 number average% (standard deviation σ ═ 0.8), and a yield of 91.5%.

Example 17

in the flow of the grinding and classifying step shown in FIG. 24, cleaning means (reverse air flow A and reverse air flow B; intermittent injection of compressed air) were used for the automatic adjusting means 21 shown in FIG. 25, and then the particles were ground and classified for 5 hours, and the particle diameter distribution of the particles were measured every 30 minutes in the same manner as in example 1. The toner had a number average particle diameter of 7.65 μm, a mass average particle diameter of 9.1 μm, a content of powdery particles having a particle diameter of 4.0 μm or less of 18.5 number average% (standard deviation σ ═ 0.6), and a yield of 91.5%.

The particles returned to the second cyclone unit 8 to which the particles were returned had a mass average particle diameter of 4.8 μm, a number average particle diameter of 3.8 μm, and a content of powdery particles having a particle diameter of 4.0 μm or less of 73 number average%. The particles collected from the upper portion of the second cyclone unit 8 to which the particles were returned had a mass average particle diameter of 3.6 μm, a number average particle diameter of 2.6 μm, and a content of powdery particles having a particle diameter of 4.0 μm or less of 90 number average%.

TABLE 1

As can be seen from the results of Table 1, in the grinding and classifying steps in examples 1 to 17, the content of the powdery particles having a particle diameter of 4.0 μm or less in the ground and classified toner was small as compared with that in the conventional grinding and classifying step (comparative example 1), and therefore the toner could be accurately and stably classified, and the yield of the toner product was also improved.

The method for producing a toner of the present invention comprises a step of grinding and classifying the toner (finely ground particles and classifying coarse particles, classifying powdery particles), wherein by giving an additional function to the present situation, more powdery particles than necessary contained in the toner as a product can be accurately classified without adding a classifier in the step, and a toner having excellent quality characteristics can be stably and easily produced, and therefore the method for producing a toner is excellent in productivity. Therefore, a toner for electrostatic latent images having a stable charge amount can be provided, and excellent image quality can be obtained.

Claims

1. A method of producing a toner comprising:

a milling step including finely milling particles and classifying coarse particles using at least one mill and cyclone unit; and

a classifying step including classifying the powdery particles using at least one classifier and a cyclone unit,

wherein any of the powdery particles and other particles classified and returned by the classifier in the classifying step are returned to the cyclone unit in the milling step, and the amount of particles in the cyclone unit to which the particles are returned in the milling step is adjusted to a constant amount.

2. The method for producing toner according to claim 1, wherein at least one grinder, one cyclone unit, and one classifier are used in the grinding step.

3. The method of producing toner according to claim 1, wherein the cyclone unit comprises a cyclone.

4. The method for producing toner according to claim 1, wherein the constant amount is 15% to 35% of the total volume of the cyclone unit.

5. The method for producing a toner according to claim 1, wherein a particle introducing pipe includes a constricted part of a classifier in the classifying step, and a cross section a1 of the particle introducing pipe and a cross section a2 of the constricted part satisfy the following relationship:

1×(A1/20)≤A2≤10×(A1/20)。

6. the method for producing toner according to claim 1, wherein a return pipe that returns the particles to the cyclone unit includes a constricted portion, and a cross section B1 of the return pipe and a cross section B2 of the constricted portion satisfy the following relationship:

1×(B1/20)≤B2≤10×(B1/20)。

7. the method for producing toner according to claim 1, wherein an upper suction pipe of the cyclone unit to which particles are returned includes a constricted portion, and a cross section D1 of the upper suction pipe and a cross section D2 of the constricted portion satisfy the following relationship:

1×(D1/20)≤D2≤10×(D1/20)。

8. the method for producing toner according to claim 1, wherein a cross section C1 of the cylindrical portion of the cyclone unit to which particles are returned and a cross section C2 of the return pipe returning particles to the cyclone unit satisfy the following relationship:

1×(C1/2000)≤C2≤200×(C1/2000)。

9. the method for producing toner according to claim 1, wherein an insertion angle θ of the return pipe that returns particles to the cyclone unit with respect to a vertical line in a longitudinal direction of an insertion position where the return pipe is inserted into the cyclone unit is 30 ° to 150 °.

10. The method for producing toner according to claim 1, wherein in the cyclone unit to which particles are returned, a height L1 from a bottom end of a conical portion to a top end of the cylindrical portion and a height L2 from the insertion position of the return pipe returning particles to the cyclone unit to a top end of the cylindrical portion of the cyclone unit satisfy the following relationship:

1×(L1/10)≤L2≤9×(L1/10)。

11. the method for producing toner according to claim 1, wherein the amount of particles in the cyclone unit to which particles are returned is adjusted by secondary air from a secondary air pipe arranged on the cyclone unit.

12. The method of producing toner according to claim 11, wherein a position where the secondary air pipe is arranged on the cyclone unit to which the particles are returned is higher than any one of a position where the return pipe is arranged on the cyclone unit and a surface of the particles in the cyclone unit.

13. The method for producing toner according to claim 1, wherein the amount of particles in the cyclone unit to which particles are returned is adjusted by a blower flow rate of a collector located above the cyclone unit, and the blower flow rate is 70% or more of a maximum flow rate.

14. The method for producing toner according to claim 1, wherein an amount of particles in the cyclone unit to which particles are returned is adjusted by compressed air from the classifier in the classifying step, and the compressed air pressure is 0.2MPa to 0.6MPa and the compressed air flow rate is 0.5m³Min to 2.5m³/min。

15. The method for producing toner according to claim 1, wherein the amount of particles in the cyclone unit to which particles are returned is adjusted by static pressure, and the first static pressure P1 of the upper part of the cyclone unit is-10 kPa to-30 kPa.

16. The method of producing toner according to claim 1, wherein the amount of particles in the cyclone unit to which particles are returned is adjusted by the static pressure, and a pressure difference Δ P (| P1-P2|) between the first static pressure P1 of an upper portion of the cyclone unit and a second static pressure P2 of a lower portion of the cyclone unit is 5kPa or less.

17. The method for producing toner according to claim 1, wherein in the cyclone unit to which the particles are returned, the secondary air flow rate is adjusted by an automatic adjusting device.

18. The method for producing toner according to claim 17, wherein the automatic adjustment device comprises a cleaning device.

19. The method for producing toner according to claim 1, wherein the particles returned to the cyclone unit have a mass average particle diameter of 5.5 μm or less, a number average particle diameter of 4.5 μm or less, and a content of powdery particles having a particle diameter of 4.0 μm or less of 40 number average% or more.

20. The method for producing toner according to claim 1, wherein the particles collected from the upper portion of the cyclone unit to which the particles are returned have a mass average particle diameter of 4.0 μm or less, a number average particle diameter of 3.0 μm or less, and a content of the powdery particles having a particle diameter of 4.0 μm or less of 70 number average% or more.

21. The method of producing toner according to claim 1, characterized in that the cyclone unit in the grinding step is followed by a step that occurs in the classifier of the classifying step.

22. The method for producing toner according to claim 1, comprising:

a first milling step and a second milling step, each comprising finely milling particles and classifying coarse particles using at least first and second mills and first and second cyclone units; and

a classifying step including classifying the powdery particles using at least first and second classifiers and third and fourth cyclone units,

wherein any of the powdery particles and other particles classified and returned by the second classifier in the classifying step are returned to the second cyclone unit in the milling step through a return pipe.