Patent Grant
8403149
1. Field of the Invention
The present invention relates to a cyclone apparatus for classifying and collecting a powder, and more particularly to a cyclone classifier and a flash drying system for drying and preparing a toner.
2. Discussion of the Background
Recently, powder is required to have sophisticated features such as a small particle diameter and a sharp particle diameter distribution. A powder having a broad particle diameter distribution has various uneven performances. The powder preferably has a uniform particle diameter to have high performances. A toner having a broad particle diameter distribution for use in electrophotography is also disadvantageous for its required uses such as being uniformly charged and melted.
Many classifying methods are known for making the particle diameter uniform. The classifying methods include a method of using a cyclone collector. Typically, the cyclone collector is used as a solid-gas separating apparatus. A powder transferred into a cyclone classifier using an airflow centrifugally accumulates on the wall of an outer cylinder with a swirling flow and gradually drops in a container installed at an under part of the outer cylinder of the cyclone classifier. The gas, which is much lighter than the particle (mostly air), is discharged out of the cyclone classifier from an inner cylinder in the center thereof.
A classifier using the cyclone collector for separating a solid from a gas, which discharges a powder having a small particle diameter together with the gas is also known. The cyclone collector is used for separating a solid from a gas and transporting a powder. A cyclone collector having an additional classifying function has an advantage of reducing capacity investment and man-hours.
The cyclone collector handles a powder having a particle diameter not greater than 1 mm.
Japanese Laid-Open Patent Publication No. 10-230223 discloses a classifying method of using a filter effect by placing a cylinder having pores between an outer cylinder and an inner cylinder of a cyclone collector. Japanese Laid-Open Patent Publication No. 8-2666938 discloses a method of controlling a classifying particle diameter by changing a gap due to pitch, wherein a slide plate changing the opening width of an entrance of a cyclone collector is arranged and the tip of a circular cone and is located facing the lower end of an outer cylinder of the cyclone collector. Further, Japanese Laid-Open Patent Publication No. 2004-283720 discloses a method of collecting an air stream including a powder in the center of the inner cylinder by increasing a flow speed with a division plate having an orifice having an area smaller than that of an end-opening of an inner cylinder, which is concentrically located in the center of an outer cylinder.
Controlling the classifying particle diameter is one of the important functions of a cyclone classifier, and a more important thing is how a powder is distributed in the order of particle diameter from smaller to larger toward the circumferential surface of anouter cylinder with a centrifugal force.
A powder having a larger particle diameter receives a stronger centrifugal force. Therefore, it is ideal that the powder having a smaller particle diameter is distributed in the center of the outer cylinder, i.e., around the inner cylinder of the cyclone classifier, and the powder having a larger particle diameter is distributed around the circumferential surface of the outer cylinder in the order of particle diameter almost continuously. When the classification point is controlled, a good-yield classifier and a classifying process separating powder having a sharp particle diameter distribution can be provided. In other words, it is necessary that a powder is specifically distributed in the order of particle diameter from the center to the circumferential surface of the outer cylinder, otherwise the powder cannot be classified even when the classification point is controlled.
In the method disclosed in Japanese Laid-Open Patent Publication No. 8-2666938, the opening width can be narrowed. However, when toner having different particle diameters is being mixed and gathered and already receiving centrifugal forces, the toner cannot be classified.
Even when a powder having a wide particle diameter distribution receives a centrifugal force on a swirling flow in the cyclone classifier when flown into the outer cylinder of a cyclone classifier, the powder cannot be classified to have desired particle diameters. This is because particles having various particle diameters, which come from the entrance varying in size, are nonuniformly mixed at a radial position where they begin to receive centrifugal forces. When a centrifugal force is further applied to the particles (the particles stay longer in the outer cylinder of the cyclone classifier), almost all the particles thinly gather on the inner wall of the outer cylinder and cannot be classified.
Because of these reasons, a need exists for a cyclone classifier capable of separating a powder having a sharp particle diameter distribution at a high yield.
Accordingly, an object of the present invention is to provide a cyclone classifier capable of separating a powder having a sharp particle diameter distribution at a high yield.
Another object of the present invention is to provide a flash drying system including the cyclone classifier.
A further object of the present invention is to provide a toner prepared by the flash drying system.
These objects and other objects of the present invention, either individually or collectively, have been satisfied by the discovery of a cyclone classifier for classifying a particulate material, including an outer cylinder including a waistless part, and an inverted-cone part vertically connected to an underside of the waistless part, and an inner cylinder comprising an exhaust opening, wherein the inner cylinder has a position-adjustable bottom end.
These and other objects, features and advantages of the present invention will become apparent upon consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.
Various other objects, features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood from the detailed description when considered in connection with the accompanying drawings in which like reference characters designate like corresponding parts throughout and wherein:
The present invention provides a cyclone classifier capable of separating a powder having a sharp particle diameter distribution at a high yield.
For example, when a polymerized toner is classified, a flash drier is used in the process of drying a wet colored and polymerized particulate material, and the cyclone collector of one embodiment of the present invention is used to separate a solid from a gas. Therefore, in an exemplary embodiment of the present invention, both the drying process and the classifying process can be performed at the same time. Alternatively, the classifying process can be performed after the drying process.
Keen studies by the present inventors of conditions of preparing a colored and polymerized particulate material having a desired sharp particle diameter distribution at a high yield, using a cyclone classifier in the process of classifying the colored and polymerized particulate material led to the present invention. After toner constituents including at least a resin and a colorant are dissolved or dispersed in an organic solvent to prepare a solution or a dispersion, the solution or the dispersion is emulsified and washed in an aqueous medium to prepare a wet cake, and the wet cake is dried with a flash drier.
Hereinafter, a first embodiment of the cyclone classifier of the present invention will be explained in detail.
A toner is exemplified in the explanations, but powder to be classified by the cyclone classifier of the present invention is not limited a polymerized toner and a pulverized toner, and any powder can be classified thereby.
As shown in
In an exemplary embodiment of the present invention, each of the outer cylinders 22, 32, 42 and 52 includes an enlarged portion 22B, 32B, 42B, and 52B. The swirl flow falls down to the bottom of the outer cylinder 22, 32, 42 and 52, swirling in the direction of an arrow from each of inlets 21, 31, 41 and 51, and is introduced into an end of each of inner cylinders 24, 34A, 34B, 44 and 54 to be discharged. A powder coming from each of the inlets 21, 31, 41 and 51 receives a centrifugal force in each of the non-enlarged portions 22A, 32A, 42A, and 52A, and almost all the particles are pressed to the circumferential surface of the non-enlarged portion 22A, 32A, 42A, and 52A. Then, the particles gather and enter the following enlarged portion 22B, 32B, 42B, and 52B in the shape of a thin film. Right after the various particles enter the enlarged portion 22B, 32B, 42B, and 52B, they leave from the circumferential surface of the non-enlarged portion 22A, 32A, 42A, and 52A and each of them is radially dispersed in accordance with its diameter by a centrifugal force applied thereto.
The centrifugal force F applied to each particle can be decided by the following formula:
F=mV2/R
wherein m represents a mass of a particle; V represents a swirling speed; and R represents a swirling radius.
The particle diameter is proportional to the mass of each particle, and the centrifugal force is applied thereto in proportion to the particle diameter and a particle diameter distribution is radially made. The particles having small particle diameters stay in the center of the enlarged portion 22B, 32B, 42B, and 52B and the particles having large particle diameters are radially distributed almost in the order of particle diameter from smallest to largest.
When the particles distributed in the order of particle diameter are aspirated from the bottom end of inner cylinder 24, 34A, 34B, 44 and 54 at a position, particles having a desired particle diameter (distribution) are very efficiently separable.
One of means of changing the classification point includes a vertically-movable inner cylinder 24, 34A, 34B, 44 and 54. However, the bottom end of the inner cylinder 24, 34A, 34B, 44 and 54 may be present within the enlarged portion 22B, 32B, 42B, and 52B.
In addition, a contracted part having a small diameter can be inserted to a connection point between the non-enlarged portion 22A, 32A, 42A, and 52A and the enlarged portion 22B, 32B, 42B, and 52B to apply larger centrifugal force to a powder toner. All particles gather in the shape of a thin film in the contracted part and widely disperse right away just when they enter the enlarged portion 22B, 32B, 42B, and 52B, and therefore they are more efficiently classified.
Further, in order to more efficiently classify particles, a baffle plate 23, 33A, 43, and 53 (also called an orifice plate) having an orifice larger than the inner cylinder diameter can be inserted in the center of the outer cylinder 22, 32, 42 and 52. The bottom end of the inner cylinder 24, 34A, 34B, 44 and 54 can be placed at the head of the baffle plate 23, 33A, 43, and 53. However, in an exemplary embodiment of the present invention, particles are effectively dispersed in the enlarged portion 22B, 32B, 42B, and 52B under the baffle plate 23, 33A, 43, and 53, and the bottom end of the inner cylinder 24, 34A, 34B, 44 and 54 may be placed at the bottom of the baffle plate 23, 33A, 43, and 53.
In the cyclone classifier of an exemplary embodiment of the present invention, one of the following relationships may be satisfied for the order of cylinder diameter:
De>1.2×Ds
De>1.2×Dr
wherein De represents a diameter of the enlarged portion 22B, 32B, 42B, and 52B; Ds represents a diameter of the non-enlarged portion 22A, 32A, 42A, and 52A; and Dr represents a diameter of the contracted part 5.
When the bottom end of the inner cylinder 24, 34A, 34B, 44 and 54 is located too far from the entrance of the enlarged portion 22B, 32B, 42B, and 52B, it is probable that the inner cylinder 24, 34A, 34B, 44 and 54 aspirates particles having undesired (large) particle diameters. Therefore, the bottom end of the inner cylinder 24, 34A, 34B, 44 and 54 is preferably located in the vertical at a position having the following distance from the connecting point between the enlarged portion 22B, 32B, 42B, and 52B and the non-enlarged portion 22A, 32A, 42A, and 52A or the contracted part 5:
10×((De−Ds)/2) or 10×((De−Dr)/2).
The inner cylinder may be a mono cylinder (as in
A cyclone classifier having plural enlarged portions, as shown in
Combinations of plural enlarged portions, plural baffle plates and multiple inner cylinders can decide a desired particle diameter and distribution thereof to more precisely classify particles.
Particles each having a large particle diameter fly out to the inner wall near the entrance of the enlarged portion. When a collection pocket is formed on the wall, only the particles each having a large particle diameter can be classified. When the position of the flow entrance to the collection pocket is controlled with a slide moving up and down, the classification point of the particles each having a large particle diameter can be controlled.
Further, when the bottom end of the inner cylinder has a control plate (not shown) controlling the flow area, the inflow speed of air stream into the inner cylinder can be controlled and stabilized.
The control plate may be a flat plate, and preferably has the shape of a cone because the air stream is aspirated into the inner cylinder without turbulence. The air stream inflow area is formed of a gap between the bottom end of the inner cylinder and the control plate.
In the partially enlarged cyclone classifier, an orifice may or may not be included in the enlarged portion, and the non-enlarged portion 2A and the enlarged portion 2B may be connected to each other through an orifice.
Next, the flash drying system using any one of the cyclone classifiers in
An exemplary flash drying system includes a feeder feeding a powder (such as a toner) upstream of a cyclone classifier 14, and a cyclone collector 16 and an exhaust fan downstream thereof.
The feeder includes a powder feeding means (such as powder feeding air 12) and a powder feeder 11, and may include a saucer 13.
A feedback means may be formed between the cyclone collector 16 and the cyclone classifier 14 to feedback a part of a classified powder to the inlet of the cyclone classifier 14.
The feedback means preferably includes an aspirating mechanism and an exhaust mechanism, such as combination of a valve and an exhaust fan 18. Alternatively, the feedback means may only include an exhaust fan 18.
Further, in an exemplary flash drying system, the cyclone classifier 14 can be a multistage classifier when the cyclone collector 16 is replaced with a feedback means. Such a classifier can easily prepare classified toners having desired particle diameters.
The cyclone classifier 14 exerts its energy-saving effect when combined with apparatuses for use in other processes. When a wet colored and polymerized particulate material is dried by a flash drier in a drying process of a polymerized toner, the colored and polymerized particulate material discharged with air flow after being dried can be separated by the cyclone classifier 14 into a solid and a gas. At that time, when the colored and polymerized particulate material is classified as well, the cost of the whole equipment can be reduced and the number of man hours can largely be reduced. This largely improves the global environment as well.
Next, a second embodiment of the cyclone classifier of the present invention, as shown in
A toner is exemplified in the explanations, but powders to be classified by the cyclone classifier of the present invention are not limited a polymerized toner and a pulverized toner, and any powder can be classified thereby.
The embodiment shown in
An alternate embodiment of the present invention will now be described with respect to
In one embodiment of the present invention, a solid-gas separation cyclone installed in other equipment can be used as a classifying cyclone. Therefore, a new power source is not required reasonably. In embodiments of the present invention, a cyclone for collecting a powder after it is subjected to a flash drying is used so as to have the capability of classifying the powder. A layout sketch of the actual flash drier and the cyclone is shown in
In
Having generally described this invention, further understanding can be obtained by reference to certain specific examples which are provided herein for the purpose of illustration only and are not intended to be limiting. In the descriptions in the following examples, the numbers represent weight ratios in parts, unless otherwise specified.
683 parts of water, 11 parts of a sodium salt of an adduct of a sulfuric ester with ethyleneoxide methacrylate (ELEMINOL RS-30 from Sanyo Chemical Industries, Ltd.), 138 parts of styrene, 138 parts of methacrylate, and 1 part of persulfate ammonium were mixed in a reactor vessel including a stirrer and a thermometer, and the mixture was stirred at 400 rpm for 15 min to prepare a white emulsion.
The white emulsion was heated to have a temperature of 75° C. and reacted for 5 hrs. Further, 30 parts of an aqueous solution of persulfate ammonium having a concentration of 1% were added thereto and the mixture was reacted for 5 hrs at 75° C. to prepare an aqueous dispersion [a particulate dispersion] of a vinyl resin (a copolymer of a sodium salt of an adduct of styrene-methacrylate-butylacrylate-sulfuric ester with ethyleneoxide methacrylate).
Further, 990 parts of water, 83 parts of the particulate dispersion 1, 37 parts of an aqueous solution of sodium dodecyldiphenyletherdisulfonate having a concentration of 48.5% (ELEMINOL MON-7 from Sanyo Chemical Industries, Ltd.) and 90 parts of ethyl acetate were mixed and stirred to prepare a lacteous liquid [an aqueous phase].
229 parts of an adduct of bisphenol A with 2 moles of ethyleneoxide, 529 parts of an adduct of bisphenol A with 3 moles of propyleneoxide, 208 parts terephthalic acid, 46 parts of adipic acid and 2 parts of dibutyltinoxide were polycondensated in a reactor vessel including a cooling pipe, a stirrer and a nitrogen inlet pipe for 8 hrs at a normal pressure and 230° C. Further, after the mixture was depressurized by 10 to 15 mm Hg and reacted for 5 hrs, 44 parts of trimellitic acid anhydride were added thereto and the mixture was reacted for 2 hrs at a normal pressure and 180° C. to prepare a low-molecular-weight polyester.
682 parts of an adduct of bisphenol A with 2 moles of ethyleneoxide, 81 parts of an adduct of bisphenol A with 2 moles of propyleneoxide, 283 parts terephthalic acid, 22 parts of trimellitic acid anhydride and 2 parts of dibutyltinoxide were mixed and reacted in a reactor vessel including a cooling pipe, a stirrer and a nitrogen inlet pipe for 8 hrs at a normal pressure and 230° C. Next, the mixture was depressurized to 10 to 15 mm Hg and reacted for 5 hrs to prepare an intermediate polyester.
Next, 410 parts of the intermediate polyester 1, 89 parts of isophoronediisocyanate and 500 parts of ethyl acetate were reacted in a reactor vessel including a cooling pipe, a stirrer and a nitrogen inlet pipe for 5 hrs at 100° C. to prepare an oil phase A.
170 parts of isophoronediamine and 75 parts of methyl ethyl ketone were reacted at 50° C. for 5 hrs in a reaction vessel including a stirrer and a thermometer to prepare a ketimine compound.
1,200 parts of water, 540 parts of carbon black Printex 35 from Degussa AG having a dibutylphthalate oil absorption of 42 ml/100 mg when measured by JIS K6221 and a pH of 9.5 and 1,200 parts of a polyester resin were mixed by a HENSCHEL MIXER from Mitsui Mining Co., Ltd. After the mixture was kneaded by a two-roll mill having a surface temperature of 150° C. for 30 min, the mixture was extended by applying pressure, cooled and pulverized by a pulverizer to prepare a masterbatch.
378 parts of the low-molecular-weight polyester, 110 parts of carnauba wax, 22 parts of charge controlling agent (salicylic acid metal complex E-84 from Orient Chemical Industries, Ltd.) and 947 parts of ethyl acetate were mixed in a reaction vessel including a stirrer and a thermometer. The mixture was heated to have a temperature of 80° C. while stirred. After the temperature of 80° C. was maintained for 5 hrs, the mixture was cooled to have a temperature of 30° C. in an hour. Then, 500 parts of the masterbatch and 500 parts of ethyl acetate were added to the mixture and mixed for 1 hr to prepare a material solution.
1,324 parts of the material solution were transferred into another vessel, and the carbon black and wax therein were dispersed by a beads mill (Ultra Visco Mill from IMECS CO., LTD.) for 3 passes under the following conditions:
liquid feeding speed of 1 kg/hr; peripheral disc speed of 6 m/sec; and filling zirconia beads having a diameter of 0.5 mm for 80% by volume.
Next, 1,324 parts of an ethyl acetate solution of the low-molecular-weight polyester having a concentration of 65% were added to the material solution and the mixture was stirred by the beads mill for 1 pass under the same conditions to prepare a pigment and wax dispersion.
664 parts of the pigment and wax dispersion and 5.9 parts of the ketimine compound were dispersed in a container to prepare an oil phase B.
74 parts of the oil phase A and 60.4 parts of the oil phase B were each fed by a pump and mixed in a Static Mixer from Noritake Co., Ltd. The uniformly mixed oil phase was joined together with 101.6 parts of the aqueous phase fed by a pump, and the mixture were sheared by a continuous emulsifier pipeline homomixer from PRIMIX Corp. at 8,400 rpm to be emulsified to prepare a slurry A wherein a microscopic oil phase droplet which becomes acolored and polymerized particulate material is present in the aqueous phase medium.
The slurry A was put in a vessel including a stirrer and a thermometer. After a solvent was removed from the slurry A at 40° C. for 8 hrs, the slurry was aged at 60° C. for 8 hrs to prepare a slurry B.
100 parts of the slurry B were subjected to solid-liquid separation by a filter press and dehydrated at 0.4 MPa to prepare a wet cake A.
100 parts of the wet cake A were uniformly dispersed in 200 parts of ion-exchanged water by a TK-type homomixer at 6,000 rpm for 30 min to prepare a dispersion slurry A.
100 parts of the dispersion slurry A were solid-liquid subjected to solid-liquid separation by a siphon-pillar centrifuge at a centrifugal effect of 1,000 G to prepare a wet cake B.
The wet cake B was dried by a flash drier. The wet cake B had a moisture content of 25% by weight.
The drying conditions were as follows:
air volume: 10 m3/min
entrance temperature: 65° C.; and
exit temperature: 33° C.
The drying speed was 0.5 kg/min. The wet cake B had a moisture content of 0.9% by weight after dried.
The colored and polymerized particulate material was classified by an experimental cyclone classifier. The cyclone classifier and the flash drying system including the cyclone classifier are shown in
The cyclone classifier used in Example 1 is shown in
Various circles therein are schematic views of the colored and polymerized particulate materials in consideration of their sizes.
The colored and polymerized particulate materials having wide particle diameter distributions, which are flown in from the inlet 21, receive centrifugal forces in the cyclone outer cylinder 22A from the swirling flow therein, and gradually descend along the cyclone outer cylinder 22A. Near the upper surface of the orifice plate 23, a hole thereof narrows the flow passage area. Therefore, the swirling speed quickly increases and the centrifugal forces applied to the colored and polymerized particulate materials quickly enlarge.
The air flow passing through the hole of the orifice plate 23 is released therefrom, and is radially dispersed by the centrifugal forces accumulated in the particles in the cyclone outer cylinder 22B. The colored and polymerized particulate material having a large particle diameter, which receives a large centrifugal force, is ejected to the wall of the enlarged portion and dispersed, and then falls along the wall of the cyclone outer cylinder 22B and is collected in a collection container (not shown) collecting desired particles. The colored and polymerized particulate material having a small particle diameter, which receives a small centrifugal force, remains in the center of the enlarge member and is discharged from the cyclone classifier with an exhaust from the cyclone inner cylinder 24.
The colored and polymerized particulate material for use in Examples and Comparative Examples had a volume-average particle diameter (Dv) of 5.8 μm and Dv/Dn (number-average particle diameter) of 1.18. The colored and polymerized particulate material includes particles having a diameter not greater than 4 μm in an amount of 14.6% by number and particles having a diameter not less than 12.7 μm in an amount of 1.3% by number.
In Example 1, the air volume of the exhaust fan was 270 m3/h, the feed amount of the colored and polymerized particulate material was 8.7 kg/h, and De (the diameter of the cyclone outer cylinder 22A)/Dr (the hole diameter of the orifice plate) was 1.6. The bottom end of the cyclone inner cylinder was placed at a position of 1×((De−Dr)/2) (=185 mm) from the bottom surface of the orifice plate.
The procedure for classification of the colored and polymerized particulate material in Example 1 was repeated to classify the colored andpolymerizedparticulate material except that the bottom end of the cyclone inner cylinder was placed at a position of 9×((De−Dr)/2) (=425 mm) from the bottom surface of the orifice plate.
The procedure for classification of the colored and polymerized particulate material in Example 1 was repeated to classify the colored andpolymerizedparticulate material except that De/Dr was 1.3 and that the bottom end of the cyclone inner cylinder was placed at a position of 5×((De−Dr)/2) (=305 mm) from the bottom surface of the orifice plate.
The procedure for classification of the colored and polymerized particulate material in Example 1 was repeated to classify the colored and polymerized particulate material except that De/Dr was 1.3 and that the bottom end of the cyclone inner cylinder was placed at a position of 9×((De−Dr)/2) (=425 mm) from the bottom surface of the orifice plate.
The procedure for classification of the colored and polymerized particulate material in Example 1 was repeated to classify the colored and polymerized particulate material except for replacing the cyclone classifier with the cyclone classifier (14 in
The procedure for classification of the colored and polymerized particulate material in Example 1 was repeated to classify the colored and polymerized particulate material except for replacing the cyclone classifier with the cyclone classifier in
The procedure for classification of the colored and polymerized particulate material in Example 1 was repeated to classify the colored and polymerized particulate material except for replacing the cyclone classifier with the cyclone classifier in
The procedure for classification of the colored and polymerized particulate material in Example 1 was repeated to classify the colored and polymerized particulate material except for replacing the cyclone classifier with the cyclone classifier in
The procedure for classification of the colored and polymerized particulate material in Example 1 was repeated to classify the colored and polymerized particulate material except that De/Dr was 1.1.
The procedure for classification of the colored and polymerized particulate material in Example 1 was repeated to classify the colored and polymerized particulate material except that De/Dr was 1.1 and that the bottom end of the cyclone inner cylinder was placed at a position of 12×((De−Dr)/2) (=515 mm) from the bottom surface of the orifice plate.
The procedure for classification of the colored and polymerized particulate material in Example 1 was repeated to classify the colored and polymerized particulate material except for using a cyclone classifier including a waistless outer cylinder without an enlarged portion and an inner cylinder. The bottom end of the cyclone inner cylinder was placed such that the inner cylinder has a length of 185 mm.
The procedure for classification of the colored and polymerized particulate material in Example 1 was repeated to classify the colored and polymerized particulate material except for using a cyclone classifier including a waistless outer cylinder without an enlarged portion and an inner cylinder. The bottom end of the cyclone inner cylinder was placed such that the inner cylinder has a length of 305 mm.
The procedure for classification of the colored and polymerized particulate material in Example 1 was repeated to classify the colored and polymerized particulate material except for using a cyclone classifier including a waistless outer cylinder without an enlarged portion and an inner cylinder. The bottom end of the cyclone inner cylinder was placed such that the inner cylinder has a length of 515 mm.
The particle diameters of 50,000 particles of each colored and polymerized particulate material classified in Examples 1 to 10 and Comparative Examples 1 to 3 were measured by a Coulter counter Multisizer from Beckman Coulter, Inc., selectively using an aperture having a diameter of 50 μm in compliance with the particle diameters of the colored and polymerized particulate material and a toner.
The results are shown in Table 1.
The contents of particles having not greater than 4 μm in Examples 1 to 5 are lower than those of the Comparative Examples. Further, Examples 1 to 5 have a better yield. In Examples 6 and 7, particles having large particle diameters are classified as well. The particles are controlled by the inlet area of the pocket collecting them. Example 8, wherein the inlet speed is faster than other Examples, can precisely classify particles at a high yield.
The colored and polymerized particulate material was classified by an experimental cyclone classifier. The cyclone classifier and the flash drying system including the cyclone classifier are shown in
The cyclone classifier used in Example 11 is shown in
The colored and polymerized particulate materials having wide particle diameter distributions, which are flown in from an inlet (2-1), receive centrifugal forces in the waistless part of the cyclone outer cylinder (2-3) from the swirling flow therein, and gradually descend along an inverted-cone part of the cyclone outer cylinder (2-4). The colored and polymerized particulate materials having a small particle diameter, which receive a centrifugal force in the waistless part of the cyclone outer cylinder (2-3) and the inverted-cone part of the cyclone outer cylinder (2-4), gather in the center of the cyclone (swirl) is discharged from the cyclone classifier of the present invention with an exhaust from a cyclone inner cylinder (2-2).
The colored and polymerized particulate material for use in Examples 11 to 18 and Comparative Examples 4 and 5 had a volume-average particle diameter (Dv) of 5.8 μm. Dv/Dn (number-average particle diameter) is a particle diameter distribution width of a powder. The closer the Dv/Dn to 1.00, the smaller the width, which means the powder has a uniform particle diameter. The Dv/Dn of the colored and polymerized particulate material was 1.18. The colored and polymerized particulate material includes particles having a diameter not greater than 4 μm in an amount of 14.6% by number, which are to be excluded.
The air volume of the exhaust fan was 270 m3/h, the feed amount of the colored and polymerized particulate material was 8.7 kg/h, the inner diameter of the cyclone outer cylinder (2-3) was 155 mm, the length of the cyclone outer cylinder (2-3) was 300 mm, the length of the inverted-cone part of the cyclone outer cylinder (2-4: length in the vertical direction) was 200 mm, an inclined angle (2-γ) between a bus bar (2-α) and a normal (2-β) was 15°, and the inner diameter of the inner cylinder (2-2) was 55 mm.
In Example 11, the length of the inner cylinder (2-2) in the cyclone was 350 mm from a top surface (2-5) of the cyclone outer cylinder.
The procedure for classification of the colored and polymerized particulate material in Example 11 was repeated to classify the colored and polymerized particulate material except that the length of the inner cylinder (2-2) in the cyclone was 400 mm from a top surface (2-5) of the cyclone outer cylinder.
The procedure for classification of the colored and polymerized particulate material in Example 11 was repeated to classify the colored and polymerized particulate material except that the length of the inner cylinder (2-2) in the cyclone was 450 mm from a top surface (2-5) of the cyclone outer cylinder.
The procedure for classification of the colored and polymerized particulate material in Example 11 was repeated to classify the colored and polymerized particulate material except that the length of the inner cylinder (2-2) in the cyclone was 460 mm from a top surface (2-5) of the cyclone outer cylinder.
The procedure for classification of the colored and polymerized particulate material in Example 11 was repeated to classify the colored and polymerized particulate material except that the inclined angle (2-γ) between a bus bar (2-α) and a normal (2-β) was 450, and the length of the inner cylinder (2-2) in the cyclone was 310 mm from a top surface (2-5) of the cyclone outer cylinder.
The procedure for classification of the colored and polymerized particulate material in Example 11 was repeated to classify the colored and polymerized particulate material except that the inclined angle (2-γ) between a bus bar (2-α) and a normal (2-β) was 450, and that the length of the inner cylinder (2-2) in the cyclone was 320 mm from a top surface (2-5) of the cyclone outer cylinder.
The double inner cylinder was used (
In Example 17, as shown in
The double inner cylinder was used as used in Example 17. As shown in
In Example 18, the procedure for classification of the colored and polymerized particulate material in Example 11 was repeated to classify the colored and polymerized particulate material except that the length of an outer tube of the inner cylinder (2-2a) in the cyclone was 440 mm from a top surface (2-5) of the cyclone outer cylinder, and that the length of an inner tube of the inner cylinder (2-2b) in the cyclone was 460 mm from a top surface (2-5) of the cyclone outer cylinder.
The procedure for classification of the colored and polymerized particulate material in Example 11 was repeated to classify the colored and polymerized particulate material except that the length of the inner cylinder (2-2) in the cyclone was 150 mm from a top surface (2-5) of the cyclone outer cylinder. The aspirating opening at the end of the cyclone inner cylinder (2-2) is located within the height of the waistless part of the cyclone outer cylinder (2-3).
The procedure for classification of the colored and polymerized particulate material in Example 11 was repeated to classify the colored and polymerized particulate material except that the length of the inner cylinder (2-2) in the cyclone was 250 mm from a top surface (2-5) of the cyclone outer cylinder. The aspirating opening at the end of the cyclone inner cylinder (2-2) is located within the height of the waistless part of the cyclone outer cylinder (2-3).
The particle diameters of 50,000 particles of each colored and polymerized particulate material classified in Examples 11 to 18 and Comparative Examples 4 and 5 were measured by a Coulter counter Multisizer from Beckman Coulter, Inc., selectively using an aperture having a diameter of 50 μm in compliance with the particle diameters of the colored and polymerized particulate material and a toner. The yield in Table 2 is a value determined by dividing the weight of the colored and polymerized particulate material collected in the collection container (1-5) after it is classified with the total weight thereof before it is classified. In other words, it can be said that the yield is a weight ratio of a powder collected in the collection container (1-5) to a total weight thereof before it is classified.
The results are shown in Table 2.
As shown in Table 2, in Comparative Examples 4 and 5, even though the aspirating opening at the end of the inner cylinder is present in the waistless outer cylinder, the classification effect is very small. In Examples 11 to 14, as the end of the inner cylinder is lowered, the content of a microscopic powder having a diameter not greater than 4 μm decreased, and the Dv/Dn representing a particle diameter distribution width also improves.
In Example 16, wherein the inclined angle between a bus bar and a normal of the inverted-cone part of the cyclone outer cylinder (2-4) was 450, the end of the inner cylinder was placed about 30 mm from the inner surface of the inverted-cone part of the cyclone outer cylinder. In Example 15, the end of the inner cylinder was placed another 10 mm therefrom. In Example 14, wherein the inclined angle between a bus bar and a normal of the inverted-cone part of the cyclone outer cylinder was 15°, the end of the inner cylinder was placed about 30 mm from the inner surface of the inverted-cone part of the cyclone outer cylinder. In Example 13, the end of the inner cylinder was placed another 10 mm therefrom. In Example 16, aspirating particles having a desired particle diameter as well as particles having a small particle diameter. Therefore, the classification preciseness in Example 16 is worse than that of Example 15. The precise control by the movement of 10 mm in Examples 15 and 16 is worse than that in Examples 13 and 14. Therefore, an inclined angle that is not less than 45° between a bus bar and a normal of the inverted-cone part of the cyclone outer cylinder is not preferable for precise classification.
Example 17, using a double inner cylinder which aspirates particles having a small particle diameter twice, can more precisely exclude only particles having a small particle diameter. Further, Example 18, using a telescopic double inner cylinder wherein the length of the outer tube of the inner cylinder (2-2a) in the cyclone was changed, can control the classifying particle diameters as desired.
This application claims priority and contains subject matter related to Japanese Patent Applications Nos. 2005-334254, 2006-070287, 2006-209635 and 2006-226266, filed on Nov. 18, 2005, Mar. 15, 2006, Aug. 1, 2006 and Aug. 23, 2006, respectively, the entire contents of each of which are hereby incorporated by reference.
Having now fully described the invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit and scope of the invention as set forth therein.
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