JP2016041396A - Minute paper powder production method using plurality of kind of crusher - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a minute paper powder production method having excellent processing capacity.SOLUTION: A minute paper powder production method includes the first pulverization step 2 for crushing coarsely crushed paper powder by using a cutting type pulverizer or an impact type pulverizer to obtain minute paper powder having an average grain size of 200 μm or less and over 100 μm, and the second pulverization step 4 for crushing the minute paper powder obtained in the first pulverization step 2 by using a grinding type pulverizer to obtain minute paper powder having an average grain size of 25 μm or more and 100 μm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fine paper powder production method for producing fine paper powder.

  In recent years, a large amount of waste paper has been discharged from offices, publishers, and paper manufacturers. Paper is a functional material having a structure with high added value, which has been subjected to advanced processing that makes cellulose fibers fine and soft at the processing stage from wood or the like. Therefore, waste paper is originally a functional material having a structure with high added value, and in addition, it becomes a raw material with virtually no environmental impact. Thus, it has been proposed to use a paper-containing resin composition in which crushed waste paper is mixed in a resin as a material for molding.

  However, if the pulverized paper contained is large, when a complicated molded product having a fine structure is injection-molded, the pulverized paper that does not show fluidity even when heated prevents the flow of the resin composition, resulting in poor filling, etc. Since defects are likely to occur and transferability is poor, a high-quality molded product cannot be obtained with a good yield. Therefore, the paper dust contained in the paper-containing resin composition needs to be fine with a maximum particle size of about 100 μm or less.

  A method for producing such fine paper powder is described in Patent Document 1, for example. In this method, a coarsely pulverized paper powder is pulverized using a vertical roller mill or a Yakuken type mill to obtain fine paper powder having an average particle size of 50 μm or more and less than 150 μm, and a first fine pulverization step. The fine paper powder in which the fine paper powder having an average particle size of 25 μm or more and less than 50 μm is mixed with the fine paper powder obtained in the above is pulverized using a vertical roller mill or a Yakuken type mill, and the fine paper powder having an average particle size of 25 μm or more and less than 50 μm A second pulverization step to obtain

Japanese Patent No. 4904389

  The manufacturing method described in Patent Document 1 has achieved a significant improvement in processing capacity as compared with the previous method using a vertical roller mill or a Yakken type mill in a single step. However, the demand for resin compositions containing fine paper powder has increased remarkably in recent years, and further mass production of fine paper powder as a raw material has been desired.

  An object of this invention is to provide the fine paper powder manufacturing method excellent in processing capacity in view of the above point.

  The fine paper powder manufacturing method of the present invention is a first method of pulverizing coarsely pulverized paper powder using a cutting pulverizer or an impact pulverizer to obtain a fine paper powder having an average particle size of more than 100 μm and not more than 200 μm. A fine pulverization step and a second fine pulverization step of pulverizing the fine paper powder obtained in the first fine pulverization step using a grinding-type pulverizer to obtain fine paper powder having an average particle size of 25 μm or more and 100 μm or less; It is characterized by providing.

  According to the fine paper powder manufacturing method of the present invention, in the first fine pulverization step, the coarse paper powder is pulverized using a cutting pulverizer or an impact pulverizer, and the fine paper having an average particle size of more than 100 μm and not more than 200 μm. I'm getting powder. The cutting-type pulverizer comes in contact with a blade that rotates at high speed to pulverize the coarse paper powder. Further, in the impact type pulverizer, the coarse paper powder on the high-speed airflow is pulverized by contacting with the fixed blade.

  Therefore, in the case of the first fine pulverization step for obtaining fine paper powder having an average particle size of more than 100 μm and not more than 200 μm, polishing is performed using a vertical roller mill or a Yakken type mill as described in Patent Document 1 above. Compared with the case of pulverizing coarse paper powder in a crushed type, pulverizing the coarse paper powder using a cutting pulverizer or impact pulverizer is superior in processing capacity and mass productivity.

  In the fine paper powder manufacturing method of the present invention, the fine paper powder obtained in the first fine pulverization step is divided into fine paper powder having a particle size of more than 100 μm and not more than 200 μm and not more than a predetermined reference particle size and particles exceeding this. Comprising a classification step of classifying into fine paper powder having a diameter, and in the second fine pulverization step, only fine paper powder having a particle size exceeding the reference particle size classified in the classification step is pulverized, and the reference particle size or less. It is preferable to obtain a fine paper powder.

  In this case, in the second fine pulverization step, only the fine paper powder classified as having a particle size exceeding the reference particle size in the classification step is pulverized using a grinding-type pulverizer, and the fine paper having the reference particle size or less. I'm getting powder. Therefore, in the second fine pulverization step, only fine paper powder classified as having a particle diameter exceeding the reference particle diameter is pulverized, and fine paper powder classified below the reference particle diameter is not pulverized. Higher productivity.

  Furthermore, since the grinding-type pulverizer only pulverizes fine paper powder having a particle size exceeding the reference particle size, the second pulverizing machine is used in comparison with a case where fine paper powder having a particle size equal to or smaller than the reference particle size is pulverized. The processing capacity in the pulverization process can be increased.

  It is more preferable if fine paper powder having an average particle size of 25 μm or more and 50 μm or less is obtained in the second fine grinding step.

  In the fine paper powder manufacturing method of the present invention, in the classification step, classification was performed using an airflow classifier, and the fine paper powder having a particle size equal to or smaller than the reference particle size classified in the classification step was obtained in the second fine pulverization step. Using a classifier equipped with a screen having a mesh corresponding to the reference particle size, fine paper powder is classified into fine paper powder less than the reference particle size and fine paper powder exceeding the reference particle size, It is preferable to provide a confirmation step for removing fine paper powder classified when the reference particle diameter is exceeded.

  In this case, since an airflow classifier, that is, a classifier that does not use a screen, is used in the classification process, there is no need for maintenance of clogging of the screen as compared with a classifier using a screen. And since the fine paper powder classified by mistake in the classification process as being below a reference particle diameter is excluded at a confirmation process, the fine paper powder exceeding a reference particle diameter does not flow into a post process.

  Further, in the fine paper powder manufacturing method of the present invention, in the classification step, classification is performed using a classifier having a mesh screen corresponding to the reference particle size, and the fine paper powder obtained in the second fine grinding step. Using a classifier having a mesh screen corresponding to the reference particle diameter, the paper is classified into fine paper powder having a particle diameter equal to or smaller than the reference particle diameter and fine paper powder exceeding the reference particle diameter, and exceeding the reference particle diameter. It is also preferable to provide a confirmation step of eliminating fine paper powder classified as follows.

  In this case, in the confirmation step, only the fine paper powder obtained in the second fine pulverization step has to be classified, so that the classification process in the confirmation step can be reduced. Therefore, the classifier used in the confirmation process can be reduced in size.

  Moreover, in the fine paper powder manufacturing method of the present invention, the cutting pulverizer or the impact pulverizer corresponds to a predetermined particle diameter that is greater than 100 μm and not greater than 200 μm and larger than the reference particle diameter. It is preferable to provide only a fine paper powder having a predetermined particle size or less in the first fine pulverization step.

  In this case, since only the fine paper powder having a predetermined particle diameter or less is obtained from the first fine pulverization step, it is possible to reduce the processing amount of the fine paper powder pulverized in the second fine pulverization step. Become.

  Furthermore, in the fine paper powder manufacturing method of the present invention, it is preferable that the fine paper powder excluded as exceeding the reference particle diameter in the confirmation step is pulverized in the second fine pulverization step.

  In this case, the fine paper powder excluded in the confirmation step can be effectively used without being discarded.

Process drawing which shows the fine paper powder manufacturing method which concerns on embodiment of this invention. Explanatory drawing which shows the fine paper powder manufacturing system which enforces the fine paper powder manufacturing method which concerns on embodiment of this invention. An example of a cutting-type crusher is shown typically, (a) is a side view, (b) is sectional drawing. The side view which shows an example of an airflow classifier typically. The side view which shows an example of an airflow classifier typically. Process drawing which shows the other fine paper powder manufacturing method which concerns on embodiment of this invention. Explanatory drawing which shows the fine paper powder manufacturing system which enforces the other fine paper powder manufacturing method which concerns on embodiment of this invention.

  An embodiment of a fine paper dust production method of the present invention and a fine paper dust production system for carrying out the same will be described with reference to FIGS.

  This fine paper powder manufacturing method pulverizes waste paper, which is a raw material, into fine paper powder having an average particle size of 25 μm or more and 100 μm or less and having a predetermined reference particle size or less. A pulverization step 2, a classification step 3, a second fine pulverization step 4, and a confirmation step 5 are provided. Hereinafter, a case where the predetermined reference particle diameter is 100 μm will be described.

  Waste paper includes waste newspaper, magazine waste, printed waste paper, packaging waste paper, corrugated waste paper, OA waste paper, and other waste paper, broken paper and waste paper generated during the manufacture of virgin paper, cutting waste such as magazines, and abrasive powder. , Shredder scraps and the like. Waste paper is discharged in large quantities from offices, publishers, paper manufacturers, etc., and it is evaluated that the environmental impact is virtually zero. In addition, the waste paper includes paper having a layer such as a resin layer on the surface, such as an end material of a paper cup.

  The average particle size of the paper powder is measured by a laser diffraction particle size distribution analyzer (manufactured by Marvern Instruments Ltd., Mastersizer S type).

  In the coarse pulverization step 1, waste paper supplied from a raw material supply machine 11 such as a supply conveyor is crushed using a coarse pulverizer 12 such as a roll crusher, a hammer mark lasher, or a cutter mill, and is about 1 mm to several tens of mm, preferably 1 mm Coarsely pulverize into 3 mm square pieces.

  When the waste paper is formed of roll-shaped or sheet-shaped broken paper, broken paper, or the like, a cutting machine or a cutting machine may be used as the coarse pulverizer 12. Note that the coarse pulverizer 12 is not required when the waste paper is a few millimeters or less, such as polishing powder obtained by polishing a book or shredder waste.

  In the first fine pulverization step 2, the coarse paper powder supplied from the coarse pulverizer 12 is made to have a maximum particle size of 100 μm using the first fine pulverizers 13A and 13B composed of a cutting pulverizer or an impact pulverizer. A predetermined particle size of more than 300 μm and an average particle size of more than 100 μm and less than 200 μm. Here, the predetermined particle diameter is larger than the above-described reference particle diameter, and is, for example, 150 μm here.

  The first fine pulverization process 2 is a two-step process from the first first fine pulverization process 2A and the second first fine pulverization process 2B. The coarse paper powder pulverized in the coarse pulverization process 1 is finely pulverized. To do.

  In the first first pulverization step 2A, the maximum particle size is a predetermined particle size exceeding 200 μm and not more than 500 μm using the first-stage first pulverizing machine 13A, and the average particle size exceeds 100 μm and exceeds 200 μm. Grind into fine paper powder of the following grade. In the second first pulverization step 2B, the fine paper powder pulverized by the first-stage first pulverizer 13A is determined in advance using the second-stage first pulverizer 13B so that the maximum particle size exceeds 100 μm and is 200 μm or less. The obtained particles are pulverized into fine paper powder having an average particle size exceeding 75 μm and not more than 150 μm.

  For example, in the first first pulverizing step 2A, pulverization is performed so that the maximum particle size is 200 μm or less, and in the second first pulverizing step 2B, pulverization is performed so that the maximum particle size is 150 μm or less.

  Here, the first pulverizers 13A and 13B are cutting pulverizers also called cutter mills. For example, as shown in FIGS. 3A and 3B, the first pulverizers 13A and 13B include a rotating cylinder 33 that rotates with a plurality of rows of rotors 32 to which a plurality of blades 31 are fixed, and A plurality of blades 34 are fixed to the inner peripheral surface, and formed in a case 35 that accommodates the rotary cylinder 33, a raw material supply port 36 for supplying a raw material between the rotary cylinder 33 and the case 35, and a lower part of the case 35. A screen 37 installed on the hole, and a discharge port 38 disposed below the screen 37 through which the crushed material is discharged. The rotating cylinder 33 has a large number of holes.

  In such a cutting pulverizer, the fineness to be crushed is determined by the gap between the blade (rotating blade) 31 and the blade (fixed blade) 34, and the pulverized material to be discharged depends on the mesh of the screen 37. The maximum particle size to be discharged is determined. The processing capacity of the cutting type pulverizer is determined by the number of blades 31, 34, the number of blades 31, 34, the number of rows of rotors 32, the number of rotations, and the like.

  Based on such characteristics of the cutting pulverizer, it is used in the cutting pulverizer (first first pulverizer) 13A used in the first first pulverizing step 2A and in the second first pulverizing step 2B. A cutting-type pulverizer (second first pulverizer) 13B is defined. As compared with the cutting crusher 13B, the cutting crusher 13A has a wider gap between the rotary blade 31 and the fixed blade 34, and the screen 37 has a coarse mesh.

  The cutting-type crusher is configured so that the amount of protrusion of the rotary blade 31 can be adjusted or can be replaced with a different amount of protrusion of the rotary blade 31, and the screen 37 can be replaced with a different mesh. . Therefore, these adjustments and exchanges may be performed according to the average particle size and the maximum particle size of the fine paper powder targeted in the first and second first pulverizing steps 2A and 2B.

  In addition, it is also possible to comprise the 1st fine grinding | pulverization process 2 only using the cutting-type grinder 13B. However, in this case, compared with the case where different cutting-type crushers 13A and 13B are used in series, the energy efficiency is generally inferior and the processing time becomes longer.

  However, when the maximum particle size of the fine paper powder obtained in the first fine pulverization step 2 is large, for example, when the maximum particle size is 200 to 500 μm, the energy efficiency and the processing time are not changed as much as the left, so one unit is cut. Only the type grinder 13B may be used. Further, in such a case, it is also preferable to increase the processing capacity by connecting the cutting pulverizers 13A and 13B in parallel with each other.

  Moreover, the 1st fine grinding | pulverization process 2 may process continuously which connected three or more types of different cutting-type grinders in series. Further, the cutting pulverizers 13A and 13B may not have the screen 27.

  Furthermore, the fine pulverizer 13 used in the first fine pulverization step 2 is not limited to a cutting pulverizer, and an impact pulverizer may be used.

  The impact type pulverizer rotates the impact plate at a high speed, thereby generating an air current in the gap between the impact plate and the housing facing the impact plate, resulting in a swirling air current. The powder collides with the impact plate. Some of the impact pulverizers include a fixed blade. In this case, even if the powder comes into contact with the fixed blade, the powder is pulverized and has the function and effect of a cutting pulverizer.

  In the impact pulverizer, the fineness of pulverization is determined by the gap between the impact plate and the housing. The processing capacity is determined by the number of impact plates, the number of rotations, and the like. Some impact pulverizers have a screen, and the maximum particle size of the fine paper powder to be discharged is determined according to the mesh of the screen.

  Further, different pulverizers may be used in each step, such as using an impact pulverizer in the first first pulverization step 2A and using a cutting pulverizer in the second first pulverization step 2B.

  In addition, when a vertical roller mill or a Yakuken type mill is used in the first fine pulverization step 2 as described in Patent Document 1, the processing capacity per unit time is small and suitable for producing a large amount of fine paper powder. Absent.

  Fine paper powder pulverized by a cutting pulverizer or impact pulverizer has a particle size distribution. The particle size distribution is not limited to the normal distribution, and changes according to the type of paper, the number of blades, the number of rotations, the rotation time, and the like. Therefore, when pulverization is performed so that the maximum particle size is 150 μm or less in the first fine pulverization step 2, fine paper powder having a particle size of 100 μm or less exists, and the ratio is often high. Therefore, except for fine paper powder having a particle size of 100 μm or less, only fine paper powder having a particle size exceeding 100 μm may be further pulverized. Therefore, these are classified in the classification step 3.

  In the classification process 3, the classifier 14 is used to classify the fine paper powder obtained in the first fine pulverization process 2 into a fine paper powder with a particle size of 100 μm or less and a fine paper powder with a particle size of over 100 μm.

  The classifier 14 is preferably an airflow classifier. The airflow classifier 14 includes a gravity type, a cyclone type, and a forced vortex flow type.

  For example, as shown in FIG. 4, the airflow classifier 14 has a classification space inside, a substantially conical cylindrical casing 41, and a raw material in which coarse powder and fine powder are mixed from the top of the casing 41. A raw material supply port 42 to be supplied, an air introduction port 43 for introducing air into the casing 41 from the top of the head, a classifying blade 44 disposed in the casing 41 and rotating, a lower part of the outer peripheral surface of the casing 41, and a rough A coarse powder discharge port 45 through which the powder is discharged and a fine powder discharge port 46 which is disposed at the upper part of the outer periphery of the casing 41 and through which the fine powder is discharged are provided.

  In such an airflow classifier 14, a swirling airflow is generated in the casing 41 by the rotation of the classifying blade 44. The coarse powder and fine powder are classified by the outward centrifugal force acting by the swirling airflow and the gas flow moving toward the center. That is, the coarse powder moves outward in the radial direction by an outward centrifugal force due to the swirling airflow, and is discharged from the coarse powder discharge port 45 disposed in the lower portion, and the fine powder is diameter-reduced by the flow of air moving toward the center. It moves to the inside in the direction and is discharged from the fine powder discharge port 46 arranged at the center.

  Therefore, the airflow classifier 14 cannot strictly classify on the basis of, for example, a particle diameter of 100 μm. However, the airflow classifier 14 that does not include a screen has an advantage that it is not necessary to eliminate clogging of the mesh and the maintenance is easy. In the classification step 3 of the present embodiment, the airflow classifier 14 is used to classify into fine powder having a particle size of 100 μm or less and fine paper powder having a particle size exceeding 100 μm. Then, the fine paper powder whose particle size exceeds 100 μm by the airflow classifier 14 is sent to the second fine grinding step 4.

  The fine paper powder discharged from the coarse powder discharge port 45 is assumed to have a particle size of more than 100 μm in the classification step 3, and is sucked by the suction device 15 and returned to the subsequent first fine pulverizer 13B to be pulverized again. . In order to simplify the process, the fine paper powder having a particle size exceeding 100 μm may be discarded. The particle size is assumed to be 100 μm or less in the classification step 3, and the fine paper powder discharged from the fine powder discharge port 46 is sucked by the suction machine 16 and temporarily stored in a container 17 such as a tank.

  In the second fine pulverization step 4, fine paper powder whose particle size exceeds 100 μm by the airflow classifier 14 is pulverized using the second fine pulverizer 18 so that the particle size becomes 100 μm or less. The second fine grinding machine 18 is a grinding type grinding machine such as a vertical roller mill, a Yakuken type mill, a stone mill type mill or the like. The fine paper powder pulverized by the second fine pulverizer 18 is sucked by the suction device 19 and temporarily stored in a container 17 such as a tank.

  The vertical roller mill represents a roller mill, and is a roller-type pulverizer that is also simply called a “roller mill”. The vertical roller mill includes a rotary table that is rotationally driven by a motor inside a cylindrical pulverizing chamber, and a plurality of vertical pulverizing rollers arranged with a gap in the rotation direction of the rotary table. . Specific examples of the saddle type roller mill include those described in Patent Document 1.

  The crushing roller is a free roller configured so that a load is applied to the rotary table by hydraulic pressure, a spring, or the like, and rotates following the rotation of the rotary table. Along with the rotation of the rotary table, paper powder is caught between the land of the crushing roller and the inner wall of the crushing chamber and pulverized. Instead of the rotary table that rotates while supporting the lower part of the grinding roller, a suspension member that rotates while supporting the upper part of the grinding roller (suspending the grinding roller) may be used. A concave groove may be formed on the inner wall of the pulverization chamber, but it is preferable that the inner surface of the pulverization chamber is smooth because paper dust may accumulate in the concave groove and the pulverization effect may be reduced.

  Fine paper powder having a particle size exceeding 100 μm sent from the classification step 3 is supplied into the pulverizing chamber, moved to the outer periphery of the rotating table by the centrifugal force of the rotating table, and is caught between the rotating table and the pulverizing roller. Is mainly pulverized. Air is introduced into the pulverization chamber from the outside, and the fine paper powder that is pulverized and made fine by the air blown up by the vanes is blown up to the upper portion of the pulverization chamber.

  Note that fine paper powder having a particle size of 100 μm or less is discharged through an airflow classifier installed at the top of the grinding chamber. The particle size of the fine paper powder discharged can be adjusted by the number of rotations of the rotating blades of the classifier.

  In the second fine grinding step 4, a Yakuken type mill or a stone mill type mill may be used instead of the vertical roller mill. However, a stone mill is inferior in energy efficiency and is not preferable.

  The Yakuken type mill is provided with a plurality of disk-shaped rotating rollers that are rotated by a motor inside an outer cylindrical housing having a bottom having a V-shaped groove in a circumferential shape. The rotating roller is disposed with a gap between the rotating roller and the interval is adjustable.

  The fine paper powder supplied to the crushing chamber accumulates inside the groove of the crushing chamber. The paper dust collected in this groove is crushed by a rotating roller. Further, the entangled coarse fine paper powder is centrifuged and loosened by a swirling air current, and the fine paper powder collides, whereby the paper powder is crushed.

  In order to pulverize fine paper powder until the maximum particle size becomes 100 μm as in this embodiment, it is preferable from the viewpoint of energy efficiency to use a vertical roller mill or a Yakuken type mill. Fine paper powder having a maximum particle size of about 25 μm cannot be obtained by using a cutting pulverizer or an impact pulverizer, and can only be pulverized using a grinding pulverizer.

  However, the grinding-type crusher crushes fine paper powder so as to crush it, so that the impact on the machine is great, the wear is severe, and there is a lot of maintenance work such as parts replacement. Furthermore, it is inferior in energy efficiency and has little processing capacity.

  Therefore, in this embodiment, after removing fine paper powder having a maximum particle size of 100 μm or less in the classification step 3, only the fine paper powder having a maximum particle size exceeding 100 μm is ground in the second fine grinding step 4. The pulverization is performed by a second fine pulverizer 18 composed of a type pulverizer. Therefore, the amount of fine paper powder to be pulverized by using a grinding type pulverizer can be reduced, and the processing capacity and energy efficiency of the entire system are excellent.

  In the confirmation step 5, the fine paper powder classified to the particle size of 100 μm or less in the classification step 3 and the fine paper powder pulverized to the particle size of 100 μm or less obtained in the second fine pulverization step 4, that is, accommodated in the container 17. The fine paper powder is confirmed to have a particle size of 100 μm or less using a classifier 21 equipped with a screen having a mesh corresponding to a particle size of 100 μm.

  As described above, the fine paper powder classified as having a particle size of 100 μm or less by the airflow classifier 14 is not strictly limited to a particle size of 100 μm or less. Furthermore, since the fine paper powder pulverized to a particle size of 100 μm or less by the second fine pulverizer 18 is classified by the same method as the airflow classifier 14, it is not strictly that the particle size is 100 μm or less. .

  Therefore, in the confirmation step 5, the classifier 21 having a mesh screen corresponding to a particle size of 100 μm is used to ensure that the fine paper powder has a particle size of 100 μm or less. Fine paper powder having a particle size exceeding 100 μm is sucked by the suction device 22, returned to the second fine pulverizer 18, and re-ground. In order to simplify the process, the fine paper powder determined to exceed the particle size of 100 μm by the classifier 21 may be discarded.

  The classifier 21 is a classifier provided with a screen having a mesh. For example, as shown in FIG. 5, such a classifier 21 has a classification space inside, a substantially conical cylindrical casing 51, and a raw material in which coarse powder and fine powder are mixed from the top of the casing 51. , A primary air introduction port 53 for introducing primary air into the casing 51 from the top, a dispersion plate 54 disposed near the top of the casing 51, and the casing 51. The screen 55, the air brush 56 that rotates on the back surface of the screen 55, the air injection unit 57 that injects jet air to the back surface of the screen 55, and the front surface side of the screen 55 and disposed below the outer peripheral surface of the casing 51. And a coarse powder outlet 58 for discharging the coarse powder, and a fine powder outlet 59 disposed on the outer peripheral portion of the casing 51 on the back side of the screen 55 and for discharging the fine powder. There.

  In such a classifier 21, the raw material on the primary air is dispersed by the dispersion plate 54 and reaches the screen 55. The fine powder that has passed through the screen 55 is discharged from the fine powder discharge port 59. The coarse powder that cannot pass through and stays on the screen 55 is blown off by jet air and falls downward due to its own weight. Secondary air is supplied from the coarse powder outlet 58 into the classification space, and the fine powder having a light weight is blown up and is not discharged from the coarse powder outlet 58. On the other hand, the coarse powder is not blown up by the secondary air but is discharged from the coarse powder discharge port 58.

  The fine paper powder having a maximum particle size of 100 μm or less discharged from the fine powder discharge port 59 is sucked by the suction machine 22 and sent to the subsequent process. On the other hand, fine paper powder having a maximum particle size exceeding 100 μm discharged from the coarse powder outlet 58 is sucked by the suction machine 23 and re-pulverized by the second fine grinding machine 18.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to this.

  For example, the case where the classification step 3 is provided between the first fine pulverization step 2 and the second fine pulverization step 4 and the fine paper powder classified below the reference particle size is not sent to the second fine pulverization step has been described. . However, the present invention is not limited to this, and the classification step 3 may be omitted, and all the fine paper powders pulverized in the first fine pulverization step 2 may be sent to the second fine pulverization step 4.

  For example, although the case where it grind | pulverizes so that the maximum particle size of fine paper powder may be 100 micrometers or less with a reference particle size was demonstrated, it is not limited to this. The present invention is an effective method with a reference particle size exceeding 25 μm and not more than 100, but the smaller the reference particle size, the more effective. The reference particle size is preferably more than 25 μm and 75 μm or less, more preferably more than 25 μm and 50 μm or less.

  Moreover, the case where the airflow classifier 14 which is not provided with the screen which has a mesh in the classification process 3 was demonstrated. However, as shown in FIGS. 6 and 7, an air classifier 24 having a screen having a mesh may be used in the classification step 6.

  In this case, the airflow classifier 24 can be used for strict classification based on a standard particle size of 100 μm. Therefore, the fine paper powder having a particle size of 100 μm or less using the airflow classifier 24 is sent to the subsequent process as it is. Then, only fine paper powder whose particle size exceeds 100 μm by the airflow classifier 24 may be sent to the second fine pulverization step 4. Thereby, in the confirmation process 5, since it is only necessary to classify the fine paper powder obtained in the second fine pulverization process 4, the classification process in the confirmation process 5 is reduced. Therefore, the classifier 21 used in the confirmation step 5 can be reduced in size.

  In the classification step 6, a classifier other than the airflow classifier 24, for example, a classifier of another type including a screen having a mesh may be used.

  DESCRIPTION OF SYMBOLS 1 ... Coarse grinding process, 2 ... 1st fine grinding process, 2A ... 1st 1st fine grinding process, 2B ... 2nd 1st fine grinding process, 3, 6 ... Classification process, 4 ... 2nd fine grinding process 5 ... Confirmation step, 11 ... Raw material feeder, 12 ... Coarse pulverizer, 13 ... First fine pulverizer, 13A ... First-stage first fine pulverizer, cutting-type pulverizer, 13B ... Second-stage first fine pulverizer, cutting 14 ... Classifier, 14 classifier, 17 ... Container, 18 ... 2nd fine grinder, 21 ... Classifier, 24 ... Airflow classifier.

Claims (6)

A first finely pulverizing step of pulverizing the coarsely pulverized paper powder using a cutting pulverizer or an impact pulverizer to obtain fine paper powder having an average particle size of more than 100 μm and not more than 200 μm;
The fine paper powder obtained in the first fine pulverization step is pulverized using a grinding-type pulverizer to provide a second fine pulverization step to obtain fine paper powder having an average particle size of 25 μm or more and 100 μm or less. To make fine paper powder. A classification step of classifying the fine paper powder obtained in the first fine pulverization step into a fine paper powder having a particle size of more than 100 μm and not more than a predetermined reference particle size of 200 μm or less and a fine paper powder having a particle size exceeding this. With
In the second fine pulverization step, only fine paper powder having a particle size exceeding the reference particle size classified in the classification step is pulverized to obtain fine paper powder having the reference particle size or less. 2. The method for producing fine paper powder according to 1. In the classification step, classification is performed using an airflow classifier,
Using a classifier equipped with a screen having a mesh having a mesh size corresponding to the reference particle size, the fine paper powder having a particle size equal to or smaller than the reference particle size classified in the classification step and the fine paper powder obtained in the second fine pulverization step. Characterized in that it comprises a confirmation step of classifying into fine paper powder having a particle size equal to or smaller than the reference particle size and fine paper powder having a particle size exceeding the reference particle size, and removing the classified fine paper powder when the particle size exceeds the reference particle size. The method for producing fine paper powder according to claim 2. In the classification step, classification is performed using a classifier having a mesh screen corresponding to the reference particle size,
Using a classifier having a mesh screen corresponding to the reference particle size, the fine paper powder obtained in the second fine pulverization step and the fine paper exceeding the reference particle size. The fine paper powder manufacturing method according to claim 2, further comprising a confirmation step of classifying the fine paper powder into powder and removing the classified fine paper powder when the reference particle size is exceeded.   The cutting-type pulverizer or the impact-type pulverizer includes a screen having a mesh having a particle diameter of more than 100 μm and not more than 200 μm and corresponding to a predetermined particle diameter larger than the reference particle diameter. 5. The method for producing fine paper powder according to claim 2, wherein only the fine paper powder having a predetermined particle diameter or less is obtained in the pulverization step.   The fine paper powder manufacturing method according to claim 3 or 4, wherein the fine paper powder excluded as exceeding the reference particle diameter in the confirmation step is pulverized in the second fine pulverization step.

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