JP2009136710A - Roll mill and dispersion or pulverization method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roll mill which can perform ink milling and dispersing of material to be treated so as to effectively prevent re-coagulation of the material to be treated, the material to be treated being prepared by mixing fine powder, nano particles or the like in liquid, and which is suited to pulverizing and dispersing of the fine powder, nano particles or the like, and to provide a method using it. <P>SOLUTION: A roll mill body includes a rear roll 2, a middle roll 3 and a front roll 4. An ultrasonic horn 7 for irradiating the material to be treated in a bank 5 with ultrasonic is provided in the bank 5 formed of the rear roll 2 and middle roll 3. The ultrasonic horn 7 is vertically movably formed to adjust a distance from the liquid level of the material to be treated based on the detection by a displacement sensor 12. An ultrasonic horn is also provided in a doctor body in slide contact with the front roller 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is used in the manufacturing process of various products such as inks, paints, ceramics, medicines, foods, electronic materials, etc. The present invention relates to a roll mill provided with a roll of books and a dispersion or pulverization method using the roll mill.

2. Description of the Related Art Conventionally, roll mills that have a plurality of rolls having different peripheral speeds and that make solid particles in a treatment material fine particles and disperse them in a liquid by using a compression / shear action that occurs between the rolls are widely used. However, if the solid in the processing material is fine powder / nanoparticles, the fine powder / nanoparticles are very cohesive even if the aggregate is made into primary particles and then subjected to kneading / dispersion treatment. As the time elapses, the repulsion between particles often decreases or the attractive force between particles (van der Waals force) increases, resulting in a problem of reaggregation. Although it is possible to increase the zeta potential in order to increase the repulsive force between particles, or to change the medium appropriately to reduce the attractive force between particles, it is not desirable to change the formulation considering the quality characteristics of the processed material . Therefore, in order to solve the above problems, dispersion is performed by a disperser such as a kneader, a roll mill, a ball mill, a sand mill, etc. A method of dispersing has been proposed (see, for example, Patent Document 1). However, this method effectively prevents reagglomeration between particles because time elapses and the reaggregation proceeds until the processing material is fed from the disperser to the ultrasonic homogenizer via the pump. There wasn't. Further, when only the ultrasonic wave is irradiated to the processing material, there is a problem that the heat generation energy is too strong, the temperature of the processing material rises, and the product deteriorates.
JP-A-10-251561 (Claim 1, paragraphs 0006 and 0014, FIG. 1)

  The problem to be solved by the present invention is a fine powder / nanoparticle that can be subjected to kneading / dispersion treatment so as to effectively prevent re-aggregation of a processing material in which substances such as fine powder and nanoparticles are mixed in a liquid A roll mill suitable for fine pulverization / dispersion and the like, and a dispersion or pulverization method using the roll mill.

  As a result of various studies, the applicant of the present application has found that re-aggregation of fine powders and nanoparticles can be effectively prevented by irradiating the processing material with ultrasonic waves in combination with soft dispersion by a roll mill. According to the present invention, a plurality of rolls are arranged in parallel so that the substance in the processing material supplied between the rolls having different peripheral speeds into the roll mill body is finely divided by the compression / shearing action generated between the rolls and dispersed in the liquid. A doctor is slidably contacted with the roll so that the dispersion-treated treatment material is scraped from the roll and taken out from the roll mill body, and ultrasonic waves are taken until the treatment material supplied between the rolls is taken out from the roll mill body. A roll mill characterized by providing an ultrasonic horn for irradiating the treatment material with ultrasonic waves so as to be irradiated is provided, and the above problems are solved.

  According to the present invention, the ultrasonic wave preferably has a frequency of 15 kHz to 30 kHz, an amplitude of 5 μm to 50 μm, and the roll is composed of a rear roll, a middle roll, and a front roll. The sonic horn is provided at a plurality of locations along the bank between the rear roll and the middle roll, the roll mill body has a displacement sensor for detecting the liquid level of the processing material in the bank, and the ultrasonic horn is The roll mill is provided so as to be movable up and down so as to adjust the distance from the liquid level based on the detection of the displacement sensor. In addition, the ultrasonic horn is provided in a doctor portion so as to irradiate the treatment material flowing down on the doctor with ultrasonic waves, the doctor has a liquid reservoir that opens upward, and the ultrasonic horn includes the liquid horn. Dispersed or pulverized fine powder / nanoparticles in the liquid using the roll mill and any one of the roll mills provided corresponding to the reservoir or in close contact with the back surface of the doctor. And a dispersion or pulverization method characterized in that the above-mentioned problems are solved.

  The present invention is configured as described above, and an ultrasonic horn is provided on the roll mill so as to irradiate the processing material with ultrasonic waves during the dispersion processing, so that reaggregation proceeds to some extent over time as in the conventional method. Compared to ultrasonic irradiation, dispersion treatment and ultrasonic irradiation are performed at the same time, so that wetting of fine powders and nanoparticles is promoted, re-aggregation is effectively prevented, and solid-state A liquid paste can be obtained. Moreover, since the roll is normally cooled even when it is irradiated with ultrasonic waves, there is no fear that the processing material will generate heat, and the quality will not deteriorate. Furthermore, it was found that when an ultrasonic wave having a frequency of 15 kHz to 30 kHz and an amplitude of 5 μm to 50 μm was irradiated, it could be dispersed in a more stable state.

  The ultrasonic horn can be provided at an appropriate position of the roll mill. However, when the roll mill is a three roll composed of a rear roll, a middle roll, and a front roll, the ultrasonic horn is placed in a bank between the rear roll and the middle roll. It is good to provide in several places along. In such a configuration, since the roll usually has a crown, the aggregated particles having a particle size of several tens of μm existing in the processing material are used in the bank (between the supply nip) between the rear roll and the middle roll. However, since the ultrasonic wave can be evenly applied to both side portions, the aggregated particle body can be crushed and wetting can be promoted. . Further, the roll mill main body is provided with a displacement sensor for detecting the liquid level of the processing material in the bank, and the ultrasonic horn is moved up and down based on the detection of the displacement sensor so that the liquid level, the ultrasonic horn, If the distance is automatically adjusted, the ultrasonic wave can always be irradiated in an optimum state even when the liquid level rises and falls, so that stable dispersion is possible.

  In particular, in the case of performing dispersion in the nano region (when the dispersed particle size is 100 nm or less), in addition to the above configuration, an ultrasonic horn is applied to the doctor portion so that the treatment material flowing down on the doctor is irradiated with ultrasonic waves. If it is provided, the dispersion treatment of fine powder and nanoparticles becomes more stable. Then, a liquid reservoir that opens upward is formed on the inclined surface of the doctor, and the ultrasonic horn is provided corresponding to the liquid reservoir, or an ultrasonic horn on the back of the doctor is provided. The dispersion of nanoparticles is even more effective.

  The present invention can be applied to various types of roll mills. In FIGS. 1 to 3, as examples, a roll roll body 1 is provided with a rear roll 2, a middle roll 3, and a front roll 4. A three-roll mill with a doctor in sliding contact is shown. At both ends of the rear roll 2 and the middle roll 3 in the bank 5, a slat 6 is provided so that the processing material does not leak, and the processing material is supplied between the rolls and dispersed in a known manner. Material is removed from the roll mill body by the doctor.

  An ultrasonic horn for irradiating the processing material with ultrasonic waves is provided so that the processing material supplied between the rolls is irradiated with ultrasonic waves before the processing material is taken out from the roll mill body. The number of ultrasonic horns can be appropriately provided at appropriate positions. In the embodiment shown in FIG. 1, the ultrasonic horns 7 are provided at three locations along the bank 5 between the rear roll 2 and the middle roll 3. ing. The ultrasonic horn 7 is supported by a support plate 8 extending along the bank 5, and both side ends of the support plate 8 are fixed to a uniaxial table 9 so as to be movable up and down. A displacement sensor 12 for detecting the liquid level of the processing material in the bank 5 is provided at the front end of the support frame 11 extending from one side wall 10, and the support plate 8 is provided with the displacement sensor 12. Correspondingly, a through hole 13 is formed. The uniaxial table 9 moves up and down based on the detection of the displacement sensor 12 and automatically adjusts the distance between the liquid level and the ultrasonic horn 7. If desired, an ultrasonic horn may be fixedly provided.

  The frequency, amplitude, and the like of the ultrasonic horn 7 can be appropriately selected according to the properties of the processing material. However, according to the experimental results, in the case of fine powder / nanoparticles, the frequency is preferably about Best results were obtained with 15-30 kHz and amplitude of about 5-50 μm.

  4 and 5 show the structure of the doctor part, and a scraping portion 15 is provided at the rear end part of the doctor body 14 formed in a substantially trapezoidal shape in plan view so as to be in sliding contact with the front roll 4. The main body 14 is supported by a support shaft 16 that spans the side wall 10 of the roll mill main body 1. Wall plates 17 are formed on both sides of the doctor body 14, and the central portion of the inclined surface 18 where the processing material scraped off by the scraping portion 15 flows down has a substantially mountain shape in plan view that divides the processing material. A sorting plate 19 is provided. A recovery port 20 is formed at the front end of the wall plate 17 and the front end of the sorting plate 19, and a liquid reservoir 21 that opens upward is provided behind the recovery port 20. An ultrasonic horn 22 is provided corresponding to the liquid reservoir 21. The ultrasonic horn 22 is fixed to a support plate 23 that is stretched over the side wall 10 of the roll mill body 1, and the lower end enters the liquid reservoir 21. In the figure, two ultrasonic horns 22 are provided corresponding to the liquid reservoir 21, but an appropriate number of ultrasonic horns can be provided according to the number of liquid reservoirs and dispersion conditions. In addition, the ultrasonic horn can be provided in an appropriate place, and may be provided in close contact with the back surface of the doctor, for example.

Table 1, a dispersion of 15 minutes using a treatment material things dispersant and a primary particle size of ion-exchanged water of _D 50 = 21 nm particle size _D 50 = _2.652μm to the ultrafine titanium oxide was premixed The experimental results are shown. As an example, A is obtained by dispersing the above-described processing materials using the roll mill of the present invention, and immediately after being subjected to the dispersion treatment with a conventional three-roll mill, 300 W (frequency 15-30 kHz, amplitude 5-50 μm) The dispersed particle size when irradiated with sound waves was measured. As a comparative example, there were prepared a dispersion treatment using only a conventional three-roll mill (B) and a dispersion treatment only with 300w ultrasonic irradiation (C), and the average value of the dispersed particle diameter was determined. It was measured.
As a result, as shown in Table 1, in the above C, the dispersed particle size is D ₅₀ = 2.652 μm, which is almost the same as the premix stage, and ultrasonic irradiation is performed at 400 w (frequency 15-30 kHz, amplitude 5-50 μm). ) But no change was seen. In the case of B, a dispersion particle diameter of D ₅₀ = 0.296 μm was obtained, but it was re-aggregated by thickening after dispersion. On the other hand, in the case of the above A, that is, when the dispersion is performed using the roll mill of the present invention and the dispersion / pulverization method using the roll mill, a dispersion particle diameter of D ₅₀ = 0.175 μm is obtained. No reaggregation occurred.

FIG. 2 is a plan view of a part of an embodiment of the present invention, mainly a rear roll and a middle roll. It is a front view of the Example shown in FIG. It is a side view of the Example shown in FIG. It is a front view which mainly shows a doctor part. It is explanatory drawing of the liquid storage part of the doctor shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Roll mill main body 2 Rear roll 3 Middle roll 4 Front roll 5 Bank 9 Uniaxial table 12 Displacement sensor 14 Doctor main body 21 Liquid reservoir 7, 22 Ultrasonic horn

Claims (8)

  A plurality of rolls are provided in parallel on the roll mill body so that substances in the processing material supplied between the rolls having different peripheral speeds are finely divided by the compression / shearing action generated between the rolls and dispersed in the liquid. Forming a doctor in sliding contact with the roll so that the treated material is scraped from the roll and taken out from the roll mill body, and is subjected to ultrasonic irradiation until the treated material supplied between the rolls is taken out from the roll mill body. A roll mill characterized in that an ultrasonic horn for irradiating the processing material with ultrasonic waves is provided.   2. The roll mill according to claim 1, wherein the ultrasonic vibration has a frequency of 15 kHz to 30 kHz and an amplitude of 5 μm to 50 μm.   The roll mill body has a rear roll, a middle roll, and a front roll, and the ultrasonic horn is provided at a plurality of locations along the bank so as to irradiate the treatment material between the rear roll and the middle roll. The roll mill according to claim 1, wherein the roll mill is characterized.   The roll mill body has a displacement sensor that detects the liquid level of the processing material in the bank, and the ultrasonic horn can be moved up and down to adjust the distance from the liquid level based on the detection of the displacement sensor. The roll mill according to claim 3, wherein the roll mill is provided.   5. The roll mill according to claim 1, wherein the ultrasonic horn is provided in a doctor portion so as to irradiate the treatment material flowing down on the doctor with ultrasonic waves.   6. The roll mill according to claim 1, wherein the doctor has a liquid reservoir that opens upward, and the ultrasonic horn is provided corresponding to the liquid reservoir.   The roll mill according to any one of claims 1 to 6, wherein the ultrasonic horn is provided in close contact with a back surface of a doctor.   A dispersion or pulverization method comprising dispersing or pulverizing fine powders / nanoparticles in a liquid using the roll mill according to any one of claims 1 to 7.

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