JP2014114416A - Method for preparing powdered cellulose - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress clogging of the inside of a vibrating pulverizer due to a cellulose-containing raw material.SOLUTION: A method for preparing powdered cellulose comprises the steps of: using the vibrating pulverizer 10; continuously supplying the cellulose-containing raw material from a raw material supply part 131; vibrating pulverization chambers 111, 121 to pulverize the cellulose-containing raw material by a grinding medium 15; and continuously discharging the pulverized cellulose-containing raw material from a powder discharge part 132 as the powdered cellulose. The fluidizing velocity of the cellulose-containing raw material per the cross-sectional area of the open space in the pulverization chamber 111 or 121 is set within 1,000-10,000 kg/(h-m). A gas G is made to flow at 1.5-30 m/minute linear velocity in the pulverization chamber 111 or 121 from the upstream side thereof to the downstream side thereof.

Description

  The present invention relates to a method for producing powdered cellulose.

  It is generally well known that by reducing the particle size of a substance to increase the specific surface area, the reactivity of the substance is improved and properties relating to handling properties such as bulk density are changed. In the method of reducing the particle size of a substance, one of the most basic unit processes is a pulverization process. In the old days, minerals and minerals such as calcium carbonate are pulverized. A wide variety. In recent years, attention has been paid to biomass materials due to increased awareness of environmental issues. Powdered cellulose obtained by pulverizing cellulose-containing raw materials is used for cellulose ether raw materials and industrial raw materials such as cosmetics, foods, and biomass materials. It has been. And as a manufacturing method of this powdered cellulose, the method of grind | pulverizing a cellulose containing raw material using a vibration-type grinder is known. For example, Patent Documents 1 and 2 disclose that when a crushed wood material is pulverized in a vibratory pulverizer equipped with a pulverizing cylinder containing a rod-shaped pulverizing medium, steam generated in the pulverizing cylinder is released. Discloses that the air flows in the crushing cylinder.

JP 2004-188833 A JP 2004-188835 A

  When continuously pulverizing a cellulose-containing raw material using a vibration-type pulverizer, it is preferable to increase the supply amount of the cellulose-containing raw material from the viewpoint of productivity. There is a problem that clogging with a cellulose-containing raw material occurs inside the pulverizer.

  The subject of this invention is suppressing the obstruction | occlusion by the cellulose containing raw material in the inside of a vibration-type grinder.

The present invention includes a raw material supply unit, a pulverization chamber provided on the downstream side of the raw material supply unit and containing a pulverization medium, and a powder discharge unit provided on the downstream side of the pulverization chamber. Using a pulverizer, continuously supplying the cellulose-containing raw material from the raw material supply unit, vibrating the pulverization chamber to pulverize the cellulose-containing raw material with the pulverizing medium, and powdering the cellulose-containing raw material pulverized from the powder discharge unit A method for producing powdered cellulose continuously discharged as cellulose, wherein the flow rate per space cross-sectional area of the cellulose-containing raw material in the pulverization chamber is 1000 to 10,000 kg / (h · m ² ), and upstream of the pulverization chamber The gas is allowed to flow at a linear velocity of 1.5 to 30 m / min.

According to the present invention, the flow rate per space cross-sectional area of the cellulose-containing raw material in the pulverization chamber is 1000 to 10,000 kg / (h · m ² ), and the flow rate of the cellulose-containing raw material is large. By flowing the gas downstream at a linear velocity of 1.5 to 30 m / min, it is possible to suppress clogging due to the cellulose-containing raw material inside the vibration type pulverizer.

It is a front view which shows schematic structure of a vibration-type grinder. It is a left view which shows schematic structure of a vibration-type grinder. FIG. 3 is a sectional view taken along line III-III in FIG. 2. (A) is a front view of a 1st (2nd) screen, (b) is a front view which attached the mask to it. It is VV sectional drawing in FIG.

  Hereinafter, embodiments will be described in detail based on the drawings.

(Vibrating crusher)
1-3 show an example of a vibratory pulverizer that can be used in the method for producing powdered cellulose according to the embodiment.

  The vibratory crusher 10 includes a hollow cylinder-shaped upper first crushing cylinder 11 and a lower second crushing cylinder 12 that are provided so as to extend in the horizontal direction.

  A cylindrical raw material supply unit 131 is provided at one end of the first pulverizing cylinder 11 so as to communicate with the inside of the first pulverizing cylinder 11 and extend upward. A cylindrical powder discharge portion 132 is provided at one end of the second pulverizing cylinder 12 so as to communicate with the inside of the second pulverizing cylinder 12 and to extend downward. Between the other ends of the first and second pulverizing cylinders 11 and 12, a cylindrical connecting tube 133 is provided so as to communicate between the insides of the first and second pulverizing cylinders 11 and 12.

  A disc-shaped first screen 141 (intermediate screen) is provided in the first pulverizing cylinder 11 upstream of the position where the connecting pipe 133 is provided so as to partition the inside of the first pulverizing cylinder 11. Yes. As a result, a first crushing chamber 111 provided downstream of the raw material supply unit 131 is formed in the first crushing cylinder 11 on the upstream side of the first screen 141, and moreover than the first screen 141. An intermediate pulverized material storage chamber 112 is configured on the downstream side.

  A disk-shaped second screen 142 (downstream end screen) is provided inside the second pulverizing cylinder 12 so as to partition the inside of the second pulverizing cylinder 12 on the upstream side of the position where the powder discharge portion 132 is provided. It has been. As a result, a second crushing chamber 121 provided downstream of the connecting pipe 133 is formed in the second crushing cylinder 12 on the upstream side of the second screen 142 and downstream of the second screen 142. On the side, a discharged pulverized material storage chamber 122 is configured.

  Therefore, in the vibration type pulverizer 10, the first screen 141 is interposed between the first pulverization chamber 111 and the second pulverization chamber 121, and between the second pulverization chamber 121 and the powder discharge unit 132. The second screen 142 is interposed.

As shown in FIG. 4A, the first and second screens 141 and 142 are formed with a plurality of slit-shaped openings 143 provided so as to extend in parallel. Further, as shown in FIG. 4B, the first and second screens 141 and 142 can be attached and detached with a mask 144 partially covering the opening 143, and the opening area S _opening can be adjusted by the shape of the mask 144. It is configured. Here, the opening ratio of the first screen 141 (second screen 142) is determined by setting the opening area S _opening of the first screen 141 (second screen 142) to the first crushing chamber 111 (second crushing chamber) as shown in the following equation. 121) divided by the cross-sectional area S _{1 (2)} and multiplied by 100.

Opening ratio (%) of first (second) screen = (S _opening / S _{1 (2)} ) × 100

  The residence time of the pulverized product in the first pulverization chamber 111 (second pulverization chamber 121) is adjusted by the opening ratio of the first screen 141 (second screen 142), thereby controlling the particle size of the pulverized product. It can be carried out. For example, if the opening ratio of the first screen 141 (second screen 142) is lowered, the residence time of the pulverized material in the first pulverization chamber 111 (second pulverization chamber 121) becomes longer. As a result, finer pulverization is performed. You can get things.

The volumes V ₁ and V ₂ of the first and second crushing chambers 111 and 121 are 3 to 1500 L, for example. The volumes V ₁ and V ₂ of the first and second crushing chambers 111 and 121 are generally the same, but may be different. The inner diameters D ₁ and D ₂ of the first and second crushing chambers 111 and 121 are, for example, 120 to 800 mm, and the lengths L ₁ and L ₂ are, for example, 200 to 4000 mm. The inner diameters D ₁ and D ₂ and the lengths L ₁ and L _{2 of} the first and second crushing chambers 111 and 121 are generally the same, but may be different.

As shown in FIGS. 3 and 5, a plurality of rod-shaped grinding media 15 are accommodated in the first and second grinding chambers 111 and 121, respectively. The grinding medium 15 is made of, for example, a round steel bar having a circular cross-sectional shape. The diameters d ₁ and d ₂ of the grinding medium 15 are, for example, 3 to 60 mm, and the lengths l ₁ and l ₂ are shorter than the lengths L ₁ and L _{2 of} the first and second grinding chambers 111 and 121, respectively. a is _{l 1 (2)} the ratio to the length _{L 1 (2)} of the grinding chamber 111 of the _{(l 1 (2) / L} 1 (2) × 100) , for example 95 to 99.5%. The cross-sectional shape of the rod-shaped grinding medium 15 is not limited to a circle, and may be a polygon such as a quadrangle or a hexagon, an ellipse, or the like. Moreover, the material of the rod-shaped grinding medium 15 is not limited to steel, and may be stainless steel, alumina, zirconia, silicon carbide, silicon nitride, glass, or the like. Furthermore, the grinding medium 15 is not limited to a rod shape, and may be other shapes such as a ball shape having a diameter of 3 to 60 mm. The first and second grinding chambers 111 and 121 may contain either the same type of grinding media 15 or different types of grinding media 15. Specifically, for example, the rod-shaped pulverizing medium 15 may be accommodated in both the first and second pulverizing chambers 111 and 121, and the rod-shaped pulverizing medium 15 may be stored in one of the first and second pulverizing chambers 111 and 121. The grinding medium 15 may be accommodated, and the ball-shaped grinding medium 15 may be accommodated on the other side.

The filling rate of the pulverizing medium 15 in the first pulverizing chamber 111 (second pulverizing chamber 121) is determined by using the total volume V _media of the pulverizing medium 15 as the volume of the first pulverizing chamber 111 (second pulverizing chamber 121) as shown in the following formula. It can be calculated by dividing by V _{1 (2)} and multiplying by 100. Note that V _{1 (2)} = πD _{1 (2)} ² L _{1 (2)} / 4,
V _media is the sum of the volumes v of the respective grinding media provided in the grinding chamber.

Filling rate (%) of grinding media in the first (second) grinding chamber = (V _media / V _{1 (2)} ) × 100

The filling rate of the grinding medium 15 in the first grinding chamber 111 (second grinding chamber 121) can be controlled by the number n1 ₍₂₎ of the grinding media 15. The grinding rate of the grinding media 15 of the pulverized product is determined by this filling rate. Since the frequency is adjusted, the particle size of the pulverized product can be controlled accordingly. For example, if the filling rate of the grinding medium 15 in the first grinding chamber 111 (second grinding chamber 121) is increased, the grinding frequency of the ground material also increases, and as a result, a finer ground material can be obtained.

  In the vibration type pulverizer 10, both sides in the length direction of the first and second pulverization cylinders 11 and 12 are externally fitted to the frame body 161 and supported, and both sides in the width direction of each frame body 161 are respectively supported. The coil springs 162 are supported by a pair of coil springs 162 disposed in the length direction, and are therefore supported by a total of eight coil springs 162, and are therefore supported by a total of eight coil springs 162. It is supported by the gantry 163. The rotating shaft 171 is provided so as to penetrate the centers of both frame bodies 161 and be supported by the both frame bodies 161, and the first and second grinding cylinders 11, 12 are connected to the rotating shaft 171. The shaft end on the connected side is coupled to the motor 173 via the universal joint 172. The rotating shaft 171 is provided with an eccentric weight 181 at a position outside each frame body 161, and the eccentric weight 181 is accommodated in a casing 182 attached to the frame body 161.

  According to the vibratory crusher 10 having the above configuration, when the motor 173 is driven, the rotating shaft 171 rotates through the universal joint 172, and at the same time, the eccentric weight 181 also rotates. The vibration to be transmitted is transmitted to the first and second crushing cylinders 11 and 12 through the frame body 161. At this time, since the frame body 161 is supported by the gantry 163 via the coil spring 162, the first and second pulverizing cylinders 11 and 12 vibrate by their circular motions in the axial plane. The medium 15 moves inside the first and second grinding chambers 111 and 121. The radius of this circular motion is, for example, 2.5 to 12 mm, and the frequency is, for example, 8 to 40 Hz. When the raw material to be crushed is continuously supplied from the raw material supply unit 131, the raw material to be crushed is sent from one end to the other while being pulverized in the first pulverization chamber 111 of the first pulverization cylinder 11 by the movement of the pulverization medium 15. . The pulverized material that has reached the downstream end of the first pulverization chamber 111 is sent to the intermediate pulverized material storage chamber 112 through the opening 143 of the first screen 141, and then from there to the second pulverization through the connecting pipe 133. It is sent to the second crushing chamber 121 of the cylinder 12. The pulverized material sent to the second pulverization chamber 121 is sent from the other end toward one end while being further pulverized by the movement of the pulverization medium 15 in the second pulverization chamber 121 of the second pulverization cylinder 12. The pulverized material that has reached the downstream end of the second pulverization chamber 121 is sent to the discharged pulverized material storage chamber 122 through the opening 143 of the second screen 142 and then continuously recovered from there through the powder discharge portion 132. Is done.

  The vibratory pulverizer is provided with the first and second pulverizing cylinders 11 and 12 as in the vibratory pulverizer 10, and further includes a raw material supply unit at one end and a powder discharge unit at the other end. The structure provided with the single grinding | pulverization cylinder may be sufficient.

  Commercially available vibratory crushers include a vibratory mill manufactured by Chuo Kako Co., Ltd., a vibratory mill manufactured by Eurus Techno, a small vibratory rod mill manufactured by Yoshida Seisakusho, a vibratory cup mill manufactured by Fritsch in Germany, and manufactured by Nissho Science Co., Ltd. And a small vibration mill.

(Production method of powdered cellulose)
In the method for producing powdered cellulose according to the present embodiment, the cellulose-containing raw material is continuously supplied from the raw material supply unit of the vibration pulverizer, the pulverization chamber is vibrated, the cellulose-containing raw material is pulverized by the pulverization medium, and pulverized from the powder discharge unit The cellulose-containing raw material is discharged as powdered cellulose. Hereinafter, the case where the vibration pulverizer 10 is used as a vibration pulverizer will be specifically described as an example. In the vibration pulverizer 10, the cellulose-containing raw material is continuously supplied from the raw material supply unit 131. The pulverizing chambers 111 and 121 are vibrated to pulverize the cellulose-containing raw material with the pulverizing medium 15, and the pulverized cellulose-containing raw material is continuously discharged as powdered cellulose from the powder discharging unit 132. And in the manufacturing method of the powdered cellulose which concerns on this embodiment, the flow rate per space cross-sectional area of the cellulose containing raw material in a grinding | pulverization chamber shall be 1000-10000 kg / (h * m < ² >), and it is 2 pulverization chambers from upstream. The gas G is flowed downstream at a linear velocity of 1.5 to 30 m / min. In the vibration pulverizer 10, the flow rate per space cross-sectional area of the cellulose-containing raw material in the first and / or second pulverization chambers 111 and 121 is set to 1000 to 10,000 kg / (h · m ² ), and the first and In the second crushing chamber 111, 121, the gas G is flowed from the upstream to the downstream at a linear velocity of 1.5 to 30 m / min.

According to the method for producing powdered cellulose according to the present embodiment, the flow rate per space cross-sectional area of the cellulose-containing raw material in the pulverization chamber is 1000 to 10,000 kg / (h · m ² ), and the flow of the cellulose-containing raw material is as described above. Although the amount is large, blockage of the cellulose-containing raw material inside the vibration-type pulverizer can be suppressed by flowing gas from the upstream to the downstream at a linear velocity of 1.5 to 30 m / min.

<Cellulose-containing raw material>
The cellulose-containing raw material to be crushed is not particularly limited. For example, various wood chips, various tree pruned branches, thinned wood, branch wood, building waste, factory waste, etc .; Pulp such as wood pulp produced and cotton linter pulp obtained from fibers around cotton seeds; Papers such as newspapers, cardboard, magazines and fine papers; Plant stems and leaves such as rice straw and corn stalks; Plant shells such as rice husk, palm husk and coconut husk are listed. The cellulose-containing raw material to be pulverized may be one of these, or may be a mixture of two or more. Among these, the cellulose-containing raw material to be pulverized is preferably pulps or woods, and more preferably pulps.

  It is preferable to supply a cellulose-containing raw material that has been cut into chips using a cutting machine such as a shredder or a slitter cutter, for example. The size of the chip-shaped cellulose-containing raw material is preferably 1 mm square or more, more preferably 2 mm square or more, from the viewpoint of productivity, and the cellulose-containing raw material is efficiently dispersed in the vibration crusher 10. From the viewpoint, it is preferably 70 mm square or less, more preferably 50 mm square or less.

  The cellulose content of the cellulose-containing raw material is preferably 20% by mass or more, more preferably 40% by mass or more, and still more preferably 60% by mass or more. Here, the cellulose content is a mass percentage of the total content of cellulose and hemicellulose in the remaining components obtained by removing water from the cellulose-containing raw material. In the case of commercially available pulp, the cellulose content is usually 75 to 100% by mass, and examples of components other than cellulose and hemicellulose include lignin and the like.

  The water content of the cellulose-containing raw material is preferably 3 from the viewpoint of efficiently reducing the crystallization index of cellulose by pulverization using a vibratory pulverizer and more efficiently reducing the particle size of the cellulose-containing raw material. 0.5% by mass or less, more preferably 2.5% by mass or less, further preferably 2.0% by mass or less, still more preferably 1.8% by mass or less, particularly preferably 1.5% by mass or less, and particularly preferably Is 1.0 mass% or less. Although the minimum of the water content of a cellulose containing raw material is not specifically limited, Preferably it is 0.2 mass% or more. The water content of the cellulose-containing raw material can be controlled by performing a drying treatment or the like in advance. Here, the moisture content is calculated from the moisture evaporation amount at a predetermined temperature measured using an infrared moisture meter (for example, model number: MOC-120H manufactured by Shimadzu Corporation).

<Supply of cellulose-containing raw material>
In the method for producing powdered cellulose according to the present embodiment, a cellulose-containing raw material is continuously supplied from a raw material supply unit (a raw material supply unit 131 in the vibration pulverizer 10) provided at one end of a pulverization cylinder of a vibration pulverizer.

The cellulose-containing raw material is supplied at a flow rate per space sectional area of the cellulose-containing raw material in the grinding chamber (first and / or second grinding chamber 111, 121 in the vibration grinding machine 10) equipped with a grinding medium of 1000 to 1000. 10000 kg / (h · m ² ) In addition, when it has two pulverization chambers connected continuously as in the vibration pulverizer 10, it is preferable that the flow velocity per space cross-sectional area is in both the first and second pulverization chambers 111 and 121. Only one of the first and second crushing chambers 111 and 121 may be equal to or less than the flow rate per space cross-sectional area.

Here, the flow rate per space cross-sectional area of the cellulose-containing raw material is a value obtained by dividing the supply rate (kg / h) of the cellulose-containing raw material from the raw material supply unit by the space cross-sectional area (m ² ) of the grinding chamber. . The space cross-sectional area refers to the cross-sectional area of the pulverization chamber in which the cellulose-containing raw material can flow in the pulverization chamber, and when the vibration pulverizer 10 is shown as an example, the volume V of the first or second pulverization chamber 111 or 121 is determined. This is a value obtained by dividing the volume of space obtained by subtracting the total volume V _media of the grinding medium 15 by the lengths L ₁ and L ₂ of the first or second grinding chambers 111 and 121.

The flow rate per space cross-sectional area of the cellulose-containing raw material is 1000 kg / (h · m ² ) or more, but from the viewpoint of productivity, it is preferably 1200 kg / (h · m ² ) or more, more preferably 1500 kg / (h · M ² ) or more, more preferably 1600 kg / (h · m ² ) or more. In addition, the flow rate per space cross-sectional area of the cellulose-containing raw material is 10,000 kg / (h · m ² ) or less, but from the viewpoint of suppressing clogging with the cellulose-containing raw material, preferably 8000 kg / (h · m ² ) or less, More preferably, it is 5000 kg / (h * m < ² >) or less, More preferably, it is 4000 kg / (h * m < ² >) or less.

<Gas distribution>
In the method for producing powdered cellulose according to this embodiment, gas is allowed to flow from the upstream to the downstream in the grinding chamber. In addition, when it has two pulverization chambers connected continuously like the vibration pulverizer 10, it is preferable to flow the gas G to both the first and second pulverization chambers 111 and 121, but at least the space of the cellulose-containing raw material The gas G may be flowed into the crushing chamber having a flow rate per cross-sectional area of 1000 to 10000 kg / (h · m ² ). When the screen is provided at the downstream end of the pulverization chamber, it is preferable that the gas flow through the opening of the screen together with the pulverization chamber.

The means for circulating gas to the pulverization chamber is not particularly limited. For example, in the case of the vibration type pulverizer 10, the gas G is introduced from the raw material supply unit 131 together with the cellulose-containing raw material, and the first pulverization chamber 111, the intermediate pulverized material storage chamber 112, the connecting pipe 133, and the second pulverization chamber 121. , And may be discharged from the discharged pulverized material storage chamber 122, or the gas G is introduced from the raw material supply unit 131 together with the cellulose-containing raw material,
It may be discharged together with the powdered cellulose from the powder discharger 132 via the first pulverization chamber 111, the intermediate pulverized material storage chamber 112, the connecting pipe 133, the second pulverization chamber 121, and the discharged pulverized material storage chamber 122. Further, a gas introduction part may be provided in the upstream part of the first pulverization chamber 111 and discharged together with the powdered cellulose from the powder discharge part 132, or the gas introduction part and the discharged pulverized material storage chamber in the upstream part of the first pulverization chamber 111. A gas discharge unit may be provided at 122.

  The gas G is not particularly limited, and examples thereof include air, nitrogen, and other inert gases. The temperature of the gas G is not limited, but is preferably 5 to 180 ° C, more preferably 10 to 150 ° C.

The gas G is circulated so that the linear velocity of the gas G in the grinding chamber is 1.5 to 30 m / min. In the vibration pulverizer 10, it is sufficient that the linear velocity of the gas G is in a pulverization chamber in which the flow rate per space cross-sectional area of the cellulose-containing raw material is 1000 to 10,000 kg / (h · m ² ).

  Although the linear velocity of the gas G is 1.5 m / min or more, it is preferably 2 m / min or more, more preferably 3 m / min or more from the viewpoint of suppressing clogging with the cellulose-containing raw material. Although the linear velocity of the gas G is 30 m / min or less, it is preferably 28 m / min or less, more preferably 25 m / min or less from the viewpoint of suppressing clogging with the cellulose-containing raw material. That is, in order to suppress the blockage by the cellulose-containing raw material, it is necessary that the linear velocity of the gas G is not too low and not too high. Here, the linear velocity of the gas G is a value obtained by dividing the air volume per unit time of the gas G (volume in a standard state at 0 ° C. and 1 atm) by the space cross-sectional area of the grinding chamber.

<Crushing>
The cellulose-containing raw material continuously supplied from the raw material supply unit installed at one end of the pulverization cylinder is sent from one end of the pulverization cylinder toward the other end while being pulverized by the movement of the pulverization medium in the pulverization chamber of the pulverization cylinder.

  The frequency of vibration of the pulverization cylinder, that is, the pulverizer, is preferably 8 Hz or more, more preferably 10 Hz or more, and further preferably 12 Hz or more from the viewpoint of the pulverization speed. The half amplitude is preferably 2.5 mm or more, more preferably 3 mm or more, and further preferably 3.5 mm or more. On the other hand, from the viewpoint of device load, the frequency is preferably 40 Hz or less, more preferably 35 Hz or less, and further preferably 30 Hz. Further, the half amplitude is preferably 12 mm or less, more preferably 10 mm or less, and further preferably 9 mm or less.

  The diameter d of the grinding medium accommodated in the grinding chamber is preferably 3 mm or more, more preferably 5 mm or more, still more preferably 10 mm or more, and preferably 60 mm or less, more preferably from the viewpoint of the grinding efficiency of the cellulose-containing raw material. It is 50 mm or less, More preferably, it is 40 mm or less.

  The filling rate of the grinding medium in the grinding chamber is preferably 40% or more, more preferably 50% or more, still more preferably 60% or more, from the viewpoint of increasing the frequency of grinding the cellulose-containing raw material. From a viewpoint of suppressing, it is preferably 90% or less, more preferably 85% or less, and still more preferably 80% or less. The number n of the grinding media depends on the inner diameter of the grinding chamber and the diameter of the grinding media, but is, for example, 10 to 5000. For the purpose of controlling the residence time of the cellulose-containing raw material in the pulverization chamber, an open screen is preferably installed at the downstream end of the pulverization chamber. When the screen is provided at the downstream end of the pulverization chamber, the cellulose-containing raw material that has reached the downstream end of the pulverization chamber is sent to the powder discharger through the opening of the screen.

  The screen aperture ratio is preferably 0.1% or more, more preferably 0.3% or more, still more preferably 0.5% or more, and still more preferably 0.8%, from the viewpoint of suppressing clogging of the cellulose-containing raw material. Also, from the viewpoint of increasing the residence time of the cellulose-containing raw material in the pulverizing chamber and increasing the pulverizing ability, it is preferably 70% or less, more preferably 60% or less, and still more preferably 50% or less.

  In the case where the vibration crusher has two crushing cylinders as in the case of the vibration crusher 10 and has a screen at the lower end of each crushing chamber, the cellulose that has reached the downstream end of the first crushing chamber 111. The contained raw material is sent to the intermediate pulverized material storage chamber 112 via the opening 143 of the first screen 141, and then sent to the second pulverization chamber 121 of the second pulverization cylinder 12 via the connecting pipe 133. The cellulose-containing raw material sent to the second crushing chamber 121 is sent from the other end toward one end while being further crushed by the movement of the crushing medium 15 in the second crushing chamber 121 of the second crushing cylinder 12. The cellulose-containing raw material that has reached the downstream end of the second pulverization chamber 121 is sent to the discharged pulverized material storage chamber 122 through the opening 143 of the second screen 142.

  The preferable mode of the diameter and the filling rate of the grinding medium 15 in the first grinding chamber 111 and the second grinding chamber 121 is the same as the preferred range of the diameter and the filling rate of the grinding medium. The diameter and filling rate of the grinding media in the grinding media 15 and the second grinding chamber 121 may be the same or different.

  The opening ratio of the first screen and the opening ratio of the second screen are preferably 0.1% or more from the viewpoint of suppressing clogging of each cellulose-containing raw material in each grinding chamber, and each cellulose-containing raw material is ground. From the viewpoint of increasing the residence time in the chamber and increasing the grinding ability, it is preferably 50% or less. Further, from the viewpoint of increasing the retention capacity of the cellulose-containing raw material having high fluidity by being pulverized in the first pulverization chamber to increase the pulverization ability, the opening ratio of the second screen 142 is set to be the first screen. It is preferable that the aperture ratio is lower. Specifically, the aperture ratio of the first screen 141 is preferably 3% or more, more preferably 10% or more, still more preferably 20% or more, and preferably 70% or less, more preferably 60% or less, More preferably, it is 50% or less. The aperture ratio of the second screen 142 is preferably 0.1% or more, more preferably 0.3% or more, still more preferably 0.5% or more, still more preferably 0.8% or more, and preferably Is 10% or less, more preferably 8% or less, still more preferably 5% or less, and even more preferably 3% or less.

<Powdered cellulose>
The powdery cellulose-containing raw material sent to the discharged ground material storage chamber 122 is continuously recovered as powdered cellulose through the powder discharger 132.

  The average particle size of the powdered cellulose is preferably 20 μm or more, more preferably 30 μm or more, still more preferably 40 μm or more, and preferably 300 μm or less, more preferably 250 μm or less, still more preferably 200 μm or less. Here, the average particle diameter of the powdered cellulose is a volume standard at 25 ° C. measured with a laser diffraction scattering method particle size distribution measuring device (for example, model number: LS13 320 manufactured by Beckman Coulter, Inc.) for the sample powdered cellulose. Is the median diameter.

  The cellulose type I crystallization index represented by the following formula of the powdered cellulose is preferably 45% or less, more preferably 42% or less, from the viewpoint of increasing the reactivity when the obtained powdered cellulose is used as a reaction raw material. More preferably, it is 40% or less.

Cellulose type I crystallization index (%) = [(I _22.6 -I _18.5 ) / I _22.6 ] × 100
(Where I _22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in X-ray diffraction, and I _18.5 is the diffraction of the amorphous portion (diffraction angle 2θ = 18.5 °). Strength.)

  The recovered powdered cellulose may be used as a raw material as it is, or may be further finely pulverized using, for example, a high-speed rotary fine pulverizer.

(Cellulose-containing raw material)
As a cellulose-containing raw material for producing powdered cellulose, a pulp sheet (manufactured by Tembec, Biofloc HV +, cellulose content: 96% by mass) is 3 mm in length using a super cutter (RK6-800, manufactured by Sugano Seiki). A chip-like pulp (hereinafter referred to as “pulp chip”) was prepared by cutting into chips having a width of 1.5 mm and a thickness of 1 mm and drying them with a dryer.

  5 g of this pulp chip is placed on a sample pan of an infrared moisture meter (manufactured by Shimadzu Corporation, model number: MOC-120H). At the end of measurement, the amount of water evaporation was measured. And when it calculated | required the water content of a pulp chip (cellulose containing raw material) based on it, it was 0.5 mass%.

(Production of powdered cellulose)
The following Examples 1 to 3 and Comparative Examples 1 to 3 and Reference Example powdered cellulose were produced. Details are also shown in Tables 1 and 2.

<Example 1>
In Example 1, a vibration-type crusher having the same configuration as that of the vibration-type crusher 10 in the above-described embodiment (model number: YAMT-50 manufactured by Eurus Techno Co., volumes V ₁ and V _{2 of} the first and second crushing chambers: 25 2L, diameters D ₁ and D ₂ of the first and second grinding chambers: 198 mm, and lengths L ₁ and L _{2 of} the first and second grinding chambers of 820 mm) were used.

In the first and second grinding chambers, 29 steel round bar-like grinding media having diameters d ₁ and d ₂ of 30 mm and lengths l ₁ and l ₂ of 805 mm were accommodated. The filling rate of the grinding medium in each of the first and second grinding chambers is 65%. Moreover, the space cross-sectional area in each of the first and second grinding chambers is 0.0107 m ² .

  As the first screen, a screen having an aperture ratio of 43% was used without attaching a mask. In addition, a mask was attached to a screen having an aperture ratio of 43% for the second screen so that the aperture ratio was 1%.

The vibration grinder was driven at a frequency of 16.7 Hz and a single amplitude of 6.5 mm, and pulp chips were continuously supplied from the raw material supply unit at a constant raw material supply rate of 18.5 kg / h. Therefore, the flow rate per space cross-sectional area of the pulp chips in the first and second grinding chambers is 1735.2 kg / (h · m ² ).

  In addition, air (25 ° C.) was introduced at a flow rate of 50 L / min into the vibration pulverizer through a gas supply pipe inserted into the raw material supply unit. The air was discharged together with the powdered cellulose from the powder discharge section via the first pulverization chamber, the intermediate pulverized material storage chamber, the connecting pipe, the second pulverization chamber, and the discharged pulverized material storage chamber. Therefore, in the first and second crushing chambers, air flows from the upstream to the downstream, but the linear velocity is 4.7 m / min.

  In Example 1, forty minutes after driving the vibratory pulverizer, the supply of pulp chips and the driving of the vibratory pulverizer were stopped. Powdered cellulose could be produced stably and continuously for 40 minutes after driving the vibratory pulverizer.

  For the recovered powdered cellulose, the volume-based median diameter of the powdered cellulose in the air at 25 ° C. was measured by a dry method using a laser diffraction scattering method particle size distribution analyzer (model number: LS13 320 manufactured by Beckman Coulter, Inc.), and averaged The particle size was taken. (Hereafter, Examples 2 and 3 and the reference example are the same). The average particle size of the recovered powdered cellulose was 157 μm.

  The recovered powdered cellulose was measured for X-ray diffraction intensity using a desktop X-ray diffractometer Rigaku MiniFlex II manufactured by Rigaku Corporation. The measurement conditions were X-ray source: Cu / Kα-radiation, tube voltage: 40 kv, tube current: 120 mA, measurement range: diffraction angle 2θ = 5-45 °, and X-ray scan speed: 10 ° / min. Then, a cellulose I-type crystallization index was calculated based on the following formula (hereinafter the same applies to Examples 2 and 3).

Cellulose type I crystallization index (%) = [(I _22.6 -I _18.5 ) / I _22.6 ] × 100
(Where I _22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in X-ray diffraction, and I _18.5 is the diffraction of the amorphous portion (diffraction angle 2θ = 18.5 °). Strength.)
The recovered powdered cellulose had a cellulose type I crystallization index of 24%.

<Example 2>
In Example 2, the same operation as in Example 1 was performed except that air (25 ° C.) was introduced at a flow rate of 100 L / min into the vibration-type pulverizer through a gas supply pipe inserted into the raw material supply unit. . The linear velocity of air is 9.4 m / min.

  Also in Example 2, it was possible to stably produce powdered cellulose continuously for 40 minutes after driving the vibration type pulverizer.

  The average particle size of the recovered powdered cellulose was 178 μm. The recovered powdered cellulose had a cellulose I-type crystallization index of 36%.

<Comparative Example 1>
In Comparative Example 1, the same operation as in Example 1 was performed except that air was not introduced into the vibratory pulverizer.

  In Comparative Example 1, since the clogging with the pulp chip occurred 30 minutes after the vibration-type crusher was driven, the supply of the pulp chip and the driving of the vibration-type crusher were stopped.

<Comparative example 2>
In Comparative Example 2, the same operation as in Example 1 was performed, except that air (25 ° C.) was introduced at a flow rate of 350 L / min into the vibration pulverizer through a gas supply pipe inserted into the raw material supply unit. . The linear velocity of air is 32.8 m / min.

  In Comparative Example 2, since clogging with pulp chips occurred 15 minutes after driving the vibration type pulverizer, the supply of pulp chips and the drive of the vibration type pulverizer were stopped.

<Reference example>
In the reference example, pulp chips were supplied from the raw material supply unit at a raw material supply rate of 9.6 kg / h, and the same operation as in Example 1 was performed except that air was not introduced into the vibration type pulverizer. The flow rate per space cross-sectional area of the pulp chips in the first and second grinding chambers is 900.4 kg / (h · m ² ). Forty minutes after driving the vibration grinder, the supply of pulp chips and the drive of the vibration grinder were stopped.

  In this reference example, since the raw material supply speed of the pulp chip is low, the flow rate is small, and even if air is not introduced into the vibration pulverizer, the powdered cellulose is stably used for 40 minutes after the vibration pulverizer is driven. Could be manufactured continuously.

  The average particle size of the recovered powdered cellulose was 122 μm.

<Example 3>
In Example 3, a vibratory crusher having the same configuration as that of the above embodiment (model number: YAMT-200, manufactured by Eurus Techno Co., Volumes V ₁ and V _{2 of} the first and second crushing chambers: 106.9L, first And diameters D ₁ and D ₂ of the second grinding chamber: 323.7 mm, and lengths L ₁ and L _{2 of} the first and second grinding chambers of 1320 mm) were used.

In the first and second grinding chambers, 84 round steel rod-shaped grinding media having diameters d ₁ and d ₂ of 30 mm and lengths l ₁ and l ₂ of 1300 mm were accommodated. The filling rate of the grinding medium in each of the first and second grinding chambers is 71%. Moreover, the space cross-sectional area in each of the first and second grinding chambers is 0.0238 m ² .

  As the first screen, a screen having an aperture ratio of 30% was used without a mask attached. In addition, a mask was attached to the second screen with an aperture ratio of 30% so that the aperture ratio was 1%.

The vibration-type pulverizer was driven at a frequency of 16.7 Hz and a single amplitude of 6.5 mm, and pulp chips were supplied from the raw material supply section at a raw material supply speed of 45.0 kg / h. Therefore, the flow rate per space cross-sectional area of the pulp chips in the first and second grinding chambers is 1890.2 kg / (h · m ² ).

  Moreover, air (130 degreeC) was introduce | transduced with the air volume of 500 L / min into the vibration-type grinder through the gas supply pipe inserted in the raw material supply part. The air was discharged together with the powdered cellulose from the powder discharge section via the first pulverization chamber, the intermediate pulverized material storage chamber, the connecting pipe, the second pulverization chamber, and the discharged pulverized material storage chamber. Therefore, in the first and second grinding chambers, air flows from the upstream to the downstream, but the linear velocity is 21.0 m / min.

  In Example 3, 50 minutes after driving the vibratory pulverizer, the supply of pulp chips and the driving of the vibratory pulverizer were stopped. Powdered cellulose could be stably and continuously produced for 50 minutes after the vibration-type pulverizer was driven.

  The average particle size of the recovered powdered cellulose was 169 μm. The recovered powdered cellulose had a cellulose type I crystallization index of 26%.

<Comparative Example 3>
In Comparative Example 3, the same operation as in Example 3 was performed, except that nitrogen (25 ° C.) was introduced into the vibration-type pulverizer at a flow rate of 17 L / min through a gas supply pipe inserted into the raw material supply unit. . The linear velocity of nitrogen is 0.7 m / min.

  In Comparative Example 3, since the clogging with the pulp chip occurred 20 minutes after the vibration type pulverizer was driven, the supply of the pulp chip and the drive of the vibration type pulverizer were stopped.

  The present invention is useful for a method for producing powdered cellulose.

G Gas 10 Vibrating pulverizer 11 First pulverizing cylinder 111 First pulverizing chamber 112 Intermediate pulverized material accommodating chamber 12 Second pulverizing cylinder 121 Second pulverizing chamber 122 Discharged pulverized material accommodating chamber 131 Raw material supply unit 132 Powder discharging unit 133 Connecting tube 141 First screen (intermediate screen)
142 Second screen (downstream screen)
143 Opening 144 Mask 15 Grinding medium 161 Frame body 162 Coil spring 163 Mounting base 171 Rotating shaft 172 Universal joint 173 Motor 181 Eccentric weight 182 Casing

Claims (10)

Using a vibratory pulverizer comprising a raw material supply unit, a pulverization chamber provided downstream of the raw material supply unit and containing a pulverization medium, and a powder discharge unit provided downstream of the pulverization chamber The cellulose-containing raw material is continuously supplied from the raw material supply unit, the cellulose-containing raw material is pulverized by the pulverization medium by vibrating the pulverization chamber, and the cellulose-containing raw material pulverized from the powder discharge unit is continuously discharged as powdered cellulose. A method for producing powdered cellulose comprising:
The flow rate per space cross-sectional area of the cellulose-containing raw material in the pulverization chamber is 1000 to 10000 kg / (h · m ² ), and the linear flow rate is 1.5 to 30 m / min from upstream to downstream in the pulverization chamber. A method for producing powdered cellulose that flows gas.   The method for producing powdered cellulose according to claim 1, wherein the grinding medium is a rod-shaped grinding medium.   The method for producing powdered cellulose according to claim 2, wherein the rod-shaped grinding medium has a diameter of 3 to 60 mm.   The method for producing powdered cellulose according to any one of claims 1 to 3, wherein the moisture content of the cellulose-containing raw material is 0.2 to 2.5 mass%.   The method for producing powdered cellulose according to any one of claims 1 to 4, wherein a filling rate of the grinding medium in the grinding chamber is 40 to 90%.   The method for producing powdered cellulose according to any one of claims 1 to 5, wherein a downstream end screen having an opening is provided between the pulverization chamber and the powder discharge portion.   The method for producing powdered cellulose according to claim 6, wherein an opening ratio of the downstream end screen is 0.1 to 10%.   The method for producing powdered cellulose according to any one of claims 1 to 7, wherein the pulverization chamber includes an upstream first pulverization chamber and a downstream second pulverization chamber.   The method for producing powdered cellulose according to claim 8, wherein an intermediate screen having an opening is provided between the first pulverization chamber and the second pulverization chamber. A downstream end screen having an opening is provided between the second pulverization chamber and the powder discharge portion,
The method for producing powdered cellulose according to claim 9, wherein the aperture ratio of the downstream end screen is smaller than the aperture ratio of the intermediate screen.

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