JP2022072411A - Method of producing dried material, and dryer - Google Patents

Abstract

To increase the concentration of a treating object while decreasing a drying time, in a method of producing a dried material by drying a frozen material and in a dryer that starts drying a frozen material kept in a frozen state.SOLUTION: The method of producing a dried material comprising a freezing step (step S2) of freezing a liquid dispersion with a treating object dispersed in a liquid, to obtain a frozen material, and a drying step (step S4) of starting drying a frozen material kept in a frozen state to obtain a dried material, in which the drying step (step S4) is a sublimation step of allowing the frozen material to sublime by irradiating the frozen material with an electromagnetic wave while moving the frozen material.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for producing a dried product by drying the frozen product to obtain a dried product, and a drying device for starting drying while the frozen product is frozen.

Materials with excellent dispersibility in liquids are expected to be applied to fields such as foods, cosmetics, medical products, and paints. However, in order to stabilize the material (hereinafter referred to as the object to be treated) as a dispersion in which the material is uniformly dispersed in the liquid, a liquid having a mass several to several hundred times that of the object to be treated is required. In some cases, there are various problems such as prevention of spoilage, securing of storage space, increase of storage and transportation costs, and the like. In order to solve this problem, a technique for evaporating the liquid in the dispersion liquid to dry the object to be treated (for example, Patent Document 1 and the like) has been proposed. In drying the object to be treated, good resilience is required so that when the dried object to be treated is dispersed again in a liquid, it can be returned to the same state as before drying.

In the technique described in Patent Document 1, the dispersion liquid is irradiated with microwaves in a state where the evaporation temperature of the water content is reduced to about 20 ° C. to 40 ° C., and the water content in the dispersion liquid is evaporated to prepare the object to be treated. It is a technique to concentrate.

Japanese Unexamined Patent Publication No. 2019-44070

However, in the technique described in Patent Document 1, in order to maintain good stability, the concentration of the object to be treated can only be concentrated to about 10% by mass, and 90% by mass of water still remains. This is a manifestation of how difficult it is to evaporate the water content in the dispersion while suppressing the aggregation of the object to be treated, and the technique of Patent Document 1 has not yet obtained a dried product.

Further, as it is desired to shorten the drying time in Patent Document 1, the shorter the drying time is, the more preferable.

In view of the above circumstances, it is an object of the present invention to provide a method for producing a dried product and a drying apparatus, which can shorten the drying time, suppress aggregation of the object to be treated, and have good resilience at the time of redispersion. do.

The method for producing a dried product of the present invention that solves the above object is
A freezing step of freezing the dispersion liquid in which the object to be treated is dispersed in the liquid to obtain a frozen product,
It has a drying step of starting drying while the frozen product is frozen to obtain a dried product.
The drying step is a step of irradiating the frozen product with an electromagnetic wave while moving the frozen product to sublimate the frozen product.

In the method for producing a dried product of the present invention, since the dried product is started to be dried while the frozen product is frozen, the products to be treated are frozen and immobilized, so that the products to be treated do not approach each other and aggregate. Is unlikely to occur. Further, even if the frozen material is agglomerated, it can be expected that the hydrogen bond, which is the main cause of the agglomeration, is broken by irradiating the frozen material with electromagnetic waves. Further, even if the frozen product is thawed and a liquid is generated in the drying step, the liquid molecules vibrate due to the electromagnetic wave, and the aggregated object is prevented from aggregating. Further, in the drying step, by irradiating the frozen material with electromagnetic waves, the ice crystals vibrate, the sublimation speed is increased, and the drying time is shortened. Moreover, by irradiating the frozen material with electromagnetic waves while moving the frozen material, the electromagnetic waves are uniformly irradiated to the frozen material, and the above-mentioned various actions obtained by irradiating the frozen material are evenly applied. Further, the heat of sublimation is uniformly applied to the frozen product, and the drying time is further shortened.

This point will be described in more detail. A shelf-type vacuum freeze-drying technique is known as a technique for drying the frozen product while it is frozen. However, many trays used in the shelf-type vacuum freeze-dryer are filled with the dispersion liquid to a thickness of several tens of mm. Therefore, it takes time and effort. Further, the tray filled with the dispersion liquid is placed on a shelf whose temperature can be controlled, and the dispersion liquid is frozen into a frozen product. After that, it is heated from the lower surface of the tray, and only one surface on the front surface side, which is the upper surface side of the tray, becomes an exposed surface as an evaporation surface of the object to be processed, and the sublimated water vapor escapes only from this one surface. As the drying progresses and the evaporative surface is lowered due to the sublimation of the ice crystals, the temperature of the ice crystals rises due to the pressure difference (resistance) when the water vapor passes through the fine gaps where the ice crystals have disappeared. Furthermore, the temperature of the ice crystals also rises due to the heat transfer resistance to the evaporation surface. Therefore, in order to maintain the frozen state of the ice crystals, the temperature of the sublimation heat (heating temperature) must be suppressed, and it takes time to dry. It can be said that the shelf-type vacuum freeze-drying described here is static drying that does not move the object to be processed.

On the other hand, it can be said that the drying in the drying step of drying while moving the frozen product is dynamic drying. In this dynamic drying, it is possible to secure a wide exposed surface of the object to be treated from which water vapor can escape, and the pressure difference (resistance) becomes small. Further, since the sublimation heat is uniformly applied, the heat transfer resistance is unlikely to be large. From these things, the temperature of the heat of sublimation (heating temperature) can be raised, and the drying time is shortened.

As described above, according to the method for producing a dried product of the present invention, it is possible to improve the enrichment of the product to be treated as a result of suppressing the aggregation of the product to be treated while shortening the drying time.

The drying step is a step of drying under reduced pressure. That is, it is a step of heating so that the water content of the frozen product is vaporized by sublimation under reduced pressure. This drying step may be a step of moving the frozen product in the container by moving the container in which the frozen product is stored. For example, it may be a step of rotating, rocking, or vibrating the container. Alternatively, the drying step may directly move the frozen product stored in the container.

Further, since the frozen material may be thawed when the electromagnetic wave is irradiated in a state where the pressure (vacuum pressure) in the container is high (a state where the degree of vacuum is low), the pressure in the container is predetermined for the irradiation of the electromagnetic wave. It is preferable to start after the value drops to the value of (for example, 300 Pa).

Further, the electromagnetic wave may have a frequency of several MHz or more and several tens of GHz or less, and may be, for example, a short wave or an ultra-high frequency wave. That is, it may be high frequency or microwave.

also,
The freezing step is a step of freezing the dispersion liquid with a brine liquid.
It may be characterized by having a separation step of separating the brine solution from the frozen product by filtering the brine solution after the freezing step is completed and before the drying step is started.

The term "brine liquid" as used herein means a liquid having a freezing point lower than that of the liquid, that is, the liquid component of the dispersion liquid (hereinafter, the same applies).

For example, when a dispersion liquid in which an object to be treated is dispersed in water is slowly frozen, the water freezes as pure ice while removing non-water molecules as foreign substances, so that ice crystals grow large and become pieces. It is considered that the object to be treated agglomerates in the dispersion liquid that has been eliminated and concentrated. On the other hand, according to the freezing step, the dispersion liquid is frozen by the brine liquid in a very short time to form nano-sized or micron-sized ice crystals, and the object to be treated is frozen and immobilized before agglomeration. Therefore, the objects to be treated do not come close to each other, and aggregation is unlikely to occur.

Further, by the separation step, the brine solution can be easily removed to the extent that the residue in the drying step does not become a problem, and the drying step can be performed more efficiently. The separated brine solution can be reused.

The freezing step may be a step of freezing the dispersion liquid with a volatile brine liquid.

In the drying step, the brine solution vaporizes and does not remain in the object to be treated.

also,
The freezing step may be characterized as a step of freezing the dispersion liquid while stirring.

By doing so, the dispersion liquid is uniformly cooled and is less likely to aggregate.

moreover,
The freezing step may be characterized in that the dispersion liquid is discharged from the supply port into the brine liquid, and the discharged dispersion liquid is frozen by the brine liquid.

The freezing step may be a step of obtaining a string-shaped frozen product, and if the freezing step is a step of freezing the dispersion liquid while stirring, the frozen product may be a short string-shaped product. Become.

Further, the freezing step may be a step of freezing the CNF dispersion liquid in which cellulose nanofibers are dispersed in the liquid.

That is,
A freezing step of freezing a CNF dispersion in which cellulose nanofibers are dispersed in a liquid with a brine solution to obtain a frozen CNF dispersion.
The method for producing a dried product may be characterized by having a drying step of starting drying while the frozen CNF dispersion is frozen.

According to this method for producing a dried product, in the freezing step, the CNF dispersion is frozen by the brine solution in a short time, so that aggregation of CNF is suppressed, and in the drying step, the frozen state is maintained. By drying the frozen CNF dispersion as it is, a dried CNF with suppressed aggregation can be obtained.

The freezing step may be a step of freezing the CNF dispersion in a brine solution in a container different from the container used in the drying step.

Further, the liquid may be water, or may be a liquid other than water as long as it disperses CNF without aggregating and can be rapidly frozen by the brine liquid. For example, it may be a liquid having a freezing point different from that of water, or it may be a liquid in which an additive is added to water. Of course, the additive is preferably a substance that is vaporized by carrying out the method for producing a dried cellulose nanofiber described later, but this is limited as long as it is a component that does not interfere with the use and use of the dried CNF. Not.

The drying apparatus of the present invention that solves the above object is
A container for storing the frozen material in which the dispersion liquid in which the object to be treated is dispersed in the liquid is frozen,
A drying means for starting drying while the frozen product stored in the container is frozen, and a drying means.
A frozen material moving part that moves the frozen material dried by the drying means in the container, and
It is characterized by being provided with an irradiation unit that irradiates the frozen material dried by the drying means with an electromagnetic wave.

According to the drying apparatus of the present invention, since the drying means starts drying while the frozen material is frozen, the objects to be treated are frozen and immobilized, so that the objects to be processed approach each other. There is no, and aggregation is unlikely to occur. Further, even if agglomeration occurs in the frozen material, it can be expected that the irradiation unit irradiates the electromagnetic wave to break the hydrogen bond which is the main cause of the agglomeration. Furthermore, even if the frozen product melts during drying to generate a liquid, the liquid molecules vibrate due to the electromagnetic waves, and the aggregated object is prevented from aggregating. Further, when the irradiation unit irradiates the frozen material with an electromagnetic wave, the ice crystals vibrate, the sublimation speed is increased, and the drying time is shortened. Moreover, the moving portion of the frozen material causes the frozen material to move while drying, resulting in dynamic drying. In this dynamic drying, as described above, it is possible to secure a wide exposed surface in the object to be treated where water vapor can escape, and the pressure difference (pressure difference) when the water vapor passes through the fine gaps where the ice crystals have disappeared. Resistance) becomes smaller. Further, since the sublimation heat is uniformly applied, the heat transfer resistance does not become large. From these things, the temperature of the heat of sublimation (heating temperature) can be raised, and the drying time is shortened. The drying apparatus of the present invention also shortens the drying time and suppresses the aggregation of the object to be treated, so that the restorability of the object to be treated at the time of redispersion can be improved.

The frozen material movable portion may directly move the frozen material stored in the container.

Further, the frozen product may be moved in the container and irradiated with electromagnetic waves at different timings while being dried by the drying means. For example, moving in the container and being irradiated with electromagnetic waves may be performed alternately.

also,
The irradiation unit may be characterized in that it irradiates the frozen material in a state of moving in the container with an electromagnetic wave.

That is, the frozen material dried by the drying means is moved in the container and irradiated with electromagnetic waves. It is preferable that the irradiation unit is provided with an irradiation unit for low output in addition to the irradiation unit for normal output, such as intermittently irradiating electromagnetic waves or narrowing the output of electromagnetic waves for continuous irradiation. If the electromagnetic wave is constantly irradiated with normal output, the frozen material may be thawed.

also,
The frozen material movable portion may be characterized in that the frozen material stored in the container is moved in the container by moving the container.

For example, the frozen object movable portion may rotate, swing, or vibrate the container.

also,
The frozen material movable portion may be characterized in that it stirs the frozen material stored in the container.

or,
The container is
The main body that stores the brine liquid inside and
A jacket that covers the outer periphery of the main body and is supplied with a heat medium is provided.
The main body may be characterized in that the brine liquid can be cooled by supplying a heat medium to the jacket.

also,
The brine liquid stored in the main body may be provided with a supply port for supplying the dispersion liquid.

moreover,
It may be characterized in that the dispersion liquid is supplied to the brine liquid while changing the relative positional relationship between the supply port and the brine liquid stored in the main body portion.

For example, the supply port may supply the dispersion liquid while moving, or the dispersion liquid may be in a state where the supply port is fixed and the main body portion is rotating, rocking, or vibrating. May be supplied, or the dispersion liquid may be supplied while changing the positional relationship by moving both the supply port and the main body portion.

By doing so, it is possible to prevent the dispersion liquid from concentrating in one place in the brine liquid, and the dispersion liquid and the brine liquid are efficiently heat-transferred, which is preferable because the freezing time becomes shorter.

In addition, the dispersion liquid may be supplied while changing the positional relationship over the entire period in which the dispersion liquid is supplied to the brine liquid, or the dispersion liquid is supplied to the brine liquid. The dispersion liquid may be supplied (for example, intermittently) while changing the positional relationship only for a partial period.

also,
The supply port may be characterized in that the dispersion liquid is supplied so that the surface area per unit mass of the dispersion liquid supplied into the brine liquid is 0.20 m ² / kg or more.

If the surface area per unit mass of the dispersion liquid supplied into the brine liquid is less than 0.20 m ² / kg, the efficiency of heat transfer between the supplied dispersion liquid and the brine liquid becomes too low, which is short. Freezing in time becomes difficult.

The shape of the dispersion liquid supplied into the brine liquid is not limited, and may be spherical, string-shaped, cylindrical, drop-shaped, spiral, shell-shaped, butterfly-shaped, thin plate-shaped, or the like. Further, since the dispersion liquid freezes in the same shape as when it was supplied into the brine liquid, the shape at the time of freezing is selected in consideration of convenience in subsequent use of the obtained dried object to be treated. Is preferable.

also,
It may be characterized by having a filter medium that filters the brine solution inside the main body and leaves the frozen matter inside the main body.

The filter medium may be one arranged inside the main body portion, or may be freely put in and taken out from the inside of the main body portion. Further, a filtration device having a filter medium may be externally attached to the main body portion.

also,
The filter medium may be characterized in that it is arranged at a position where it does not come into contact with the dispersion liquid until the dispersion liquid freezes.

For example, the supply port is provided above the liquid level of the brine liquid, and the filter medium is arranged at the bottom of the main body for storing the brine liquid, and the supply port is provided. The dispersion liquid supplied from the above may be in a mode in which the filter medium does not come into contact with the dispersion liquid by freezing before reaching the bottom portion. Further, the main body portion can be turned upside down, and the filter medium is arranged above the liquid level of the brine liquid (upper part of the main body portion) while the dispersion liquid is supplied from the supply port. Then, the filter medium does not come into contact with the dispersion liquid, and after the supply of the dispersion liquid is completed (after all of the supplied dispersion liquid is frozen), the main body portion is turned upside down, and the filter medium is turned upside down. It may be arranged below the liquid level of the brine liquid (lower part of the main body portion). Alternatively, the filter medium can be freely taken in and out of the main body portion, and the filter medium is taken out from the inside of the main body portion while the dispersion liquid is being supplied from the supply port, and the filter medium is dispersed. After the supply of the dispersion is completed without contact with the liquid (after all of the supplied dispersion is frozen), the filter medium is placed inside the main body, and the filter medium is the brine liquid. It may be arranged below the liquid level of (the lower part of the main body).

By arranging the filter medium at a position where it does not come into contact with the dispersion liquid, it is possible to prevent the dispersion liquid from slipping through the filter medium before it freezes or from freezing the dispersion liquid in the filter medium and hindering filtration. be able to.

Further, the container described above may be used to store a frozen CNF dispersion obtained by freezing a CNF dispersion in which cellulose nanofibers are dispersed in a liquid.

According to the present invention, it is possible to provide a method for producing a dried product and a drying apparatus, which can shorten the drying time, suppress the aggregation of the object to be treated, and have good resilience at the time of redispersion.

It is a system diagram of the drying system of 1st Embodiment. 5 is a flow chart showing a method for producing a dried product of CNF. It is a figure which shows typically the state that the CNF dispersion liquid was frozen. It is a graph which shows the temperature raising program of the set temperature of a low temperature constant temperature bath. It is a figure which shows the modification of the container shown in FIG. It is a system diagram of the drying system of 2nd Embodiment. It is a figure which showed the aspect of the container while supplying a CNF dispersion liquid.

Hereinafter, the drying system incorporating the drying apparatus according to the embodiment of the present invention will be described in detail with reference to the drawings. The drying system described below is a system for drying a CNF dispersion liquid in which CNF (cellulose nanofibers) is dispersed in the liquid as an example.

FIG. 1 is a system diagram of the drying system of the first embodiment.

The drying system D1 shown in FIG. 1 includes a drying device 1 corresponding to an embodiment of the present invention, a filtrate receptor 3, a cold trap 5, and a refrigerator 6.

The drying device 1 shown in FIG. 1 includes a container 10, a vacuum pump 11 for depressurizing the inside of the container 10, and a low-temperature constant temperature bath 20. The vacuum pump 11 is provided on the downstream side of the drying system D1 shown in FIG. A combination of the low temperature constant temperature bath 20 and the vacuum pump 11 corresponds to an example of the drying means.

FIG. 1 schematically shows a state in which the container 10 is cross-sectionald in the vertical direction so that the inside of the container 10 can be seen. The container 10 is supported by a support column 10S, and has a main body 100, an upper lid 110 that covers the upper end of the main body 100, a spiral ribbon 122 that is a stirring means for rotationally driving, and an internal space of the main body 100. It has a jacket 130 to cover. The main body 100 is composed of a cylindrical upper portion 101 and an inverted conical portion 102 whose diameter is gradually reduced as the distance from the upper portion 101 increases. A discharge port 1001 is provided at the lower end of the main body 100, that is, the lower end of the inverted conical portion 102, and the discharge port 1001 is closed by an openable / closable discharge lid 140.

The upper lid 110 is provided with a slot 111. In FIG. 1, a supply pipe 111P for supplying a CNF dispersion is connected to the inlet 111. The supply pipe 111P is provided with a supply valve 111V. Further, the supply tube 111T extends from the input port 111. The supply port 1110, which is the tip of the supply tube 111T, has an opening shape that opens inside the main body 100 and has a specific surface area of 0.2 m ² / kg or more, which is the surface area per unit mass of the CNF dispersion. The opening direction points to the liquid level of the brine liquid B. Further, the shape of the supply port 1110 is not limited, and the shape of the CNF dispersion liquid supplied into the brine liquid B is spherical, cylindrical, disk-shaped, drop-shaped, spiral, shell-shaped, thin plate-shaped, butterfly-shaped, and so on. It may have a star shape, a thin flake shape, a corrugated shape, a twist shape, a prismatic shape, or the like. Alternatively, the supply port 1110 may be provided with a nozzle capable of spraying the CNF dispersion liquid. The supply tube 111T may be removed when the spiral ribbon 122 is rotationally driven.

The upper lid 110 is also provided with an exhaust port 112. An exhaust passage 112P is connected to the exhaust port 112 via an exhaust filter 113. Therefore, the gas that has passed through the exhaust filter 113 enters the exhaust passage 112P. A cold trap 5 is provided on the downstream side of the exhaust passage 112P, and a vacuum pump 11 is further installed on the downstream side thereof.

The upper lid 110 is also provided with a glass window 114. Quartz glass is fitted in the glass window 114, and electromagnetic waves are emitted from the glass window 114 toward the inside of the main body 100. The electromagnetic wave referred to here may have a frequency of several MHz or more and several tens of GHz or less, and may be, for example, a short wave or an ultra-high frequency wave. That is, it may be high frequency or microwave. More specifically, it may be a high frequency of 13.56 MHz, a microwave of 915 MHz, or a microwave of 2450 MHz.

The brine solution B is stored in the main body 100 shown in FIG. 1. The brine liquid B is a volatile liquid having a lower freezing point than the liquid (water in this embodiment) in the CNF dispersion liquid, and specifically, ethanol is used. Instead of ethanol, organic compounds such as paraffins, alicyclic hydrocarbons, alcohols and ethers with a melting point of -30 ° C or less and a boiling point of less than 100 ° C (for example, hexane, 2-methylpentane, 3-methylpentane) , 2,2-dimethylbutane, 2,3-dimethylbutane, cyclohexene, methanol, 1-propanol, 2-propanol, allyl alcohol, propyl ether, isopropyl ether, propionaldehyde, butyl aldehyde, achlorine, acetone, methyl ethyl ketone, ethyl formate , Methyl acetate, ethyl acetate, methyl propionate, triethylamine, acetonitrile, propionitrile, acrylonitrile, etc.) may be used.

Further, a filtrate discharge port 1021 is formed in the lower part of the peripheral wall of the inverted conical portion 102. A filtration member 1022 is installed in the filtrate discharge port 1021. The filtration member 1022 filters the brine liquid B, and a wire mesh is used here. As the filtering member 1022, in addition to the wire mesh, the most suitable one can be used depending on the characteristics of the brine liquid B, such as a filter cloth, a laminated material, or a ceramic. The conduit connected to the filtrate discharge port 1021 is connected to the filtrate receptor 3. A shutoff valve V2 is provided between the filtrate discharge port 1021 and the filtrate receptor 3. Further, the filtrate receptor 3 communicates with the exhaust passage 112P via the shutoff valve V3.

The spiral ribbon 122 is entirely made of resin, is supported by a plurality of rod-shaped support members radially protruding from the drive shaft 121, orbits along the vicinity of the inner peripheral wall of the main body 100, and is tapered downward. It is a spiral. The spiral ribbon 122 is rotationally driven by the drive shaft 121 rotating around the shaft. The drive shaft 121 is sealed and penetrates the upper lid 110 and is driven by the drive device 123 to rotate the spiral ribbon 122. The rotation of the spiral ribbon 122 causes a circulating flow in the brine liquid B stored in the main body 100 and the CNF dispersion liquid supplied from the charging port 111. Examples of the resin used for the spiral ribbon 122 include engineering plastics and fiber reinforced plastics (FRP).

A heat medium supply path 131 and a heat medium recovery path 132 are connected to the jacket 130 that covers the internal space of the main body 100. That is, the tip of the heat medium supply path 131 extending from the low temperature constant temperature bath 20 is connected to the lower part of the jacket 130. On the other hand, the rear end of the heat medium recovery path 132 whose tip is connected to the low temperature constant temperature bath 20 is connected to the upper part of the jacket 130. In the low temperature constant temperature bath 20, the heat medium is kept at a set temperature. If the heat medium is the same as that of the brine solution B, the brine solution B recovered in the filtrate receptor 3 can be reused. Of course, the heat medium may be different from that of the brine solution B. At least the heat medium may have a lower freezing point than the liquid in the CNF dispersion, and does not have to be volatile. The heat medium is supplied to the jacket 130 through the heat medium supply path 131, then recovered from the jacket 130 through the heat medium recovery path 132, and returned to the low temperature constant temperature bath 20. By circulating and supplying the heat medium to the jacket 130, the temperature of the main body 100 can be adjusted from the outside and the temperature inside the main body 100 can be adjusted to a desired temperature.

Subsequently, a method for producing a dried product of CNF by drying the CNF dispersion liquid using the drying system D1 shown in FIG. 1 will be described.

FIG. 2 is a flow chart showing a method for producing a dried product of CNF.

First, the brine solution B preparation step (step S1) is carried out. In this brine liquid B preparation step, the brine liquid B (here, ethanol) is supplied to the main body 100 whose inside is empty from the charging port 111 provided in the upper lid 110. The shutoff valves V2 and V3 provided downstream of the filtrate discharge port 1021 are in a closed state. In the brine liquid B preparation step, the supply tube 111T is not attached to the inlet 111, but for the brine liquid B, the supply tube 111T is attached and the CNF dispersion liquid is completely supplied in the freezing step described later. It is supplied and stored up to a height at which the supply port 1110, which is the tip of the above, is not immersed. For example, the liquid amount of the brine liquid B is such that it reaches the upper end of the inverted conical portion 102. When the supply of the brine solution B to the inside of the main body 100 is completed, it is desired that the brine solution B stored inside the main body 100 be kept below the freezing point of the CNF dispersion while keeping the inside of the main body 100 in a sealed state. Cool to the cooling temperature. For this cooling, a set temperature (here, −30 ° C.) corresponding to the cooling temperature is set in the low temperature constant temperature bath 20, and a heat medium cooled to the set temperature in the low temperature constant temperature tank 20 is circulated and supplied to the jacket 130. It is done in. The spiral ribbon 122 may be rotated during cooling. Further, the vaporized brine liquid B flowing into the exhaust passage 112P in the main brine preparation B step (and the freezing step and separation step described later) by operating the cold trap 5 and the refrigerator 6 described in detail in the drying step described later is Trapped and the non-condensed gas is exhausted under atmospheric pressure through an exhaust path (not shown).

The main body 100 is provided with a thermometer (not shown) for measuring the temperature of the brine liquid B stored inside the main body 100, and when the brine liquid B is cooled to the above cooling temperature, a freezing step is performed. (Step S2) is carried out. In this freezing step, the CNF dispersion is rapidly frozen by immersion in brine. Even during the freezing step, the heat medium cooled to the set temperature continues to be circulated and supplied to the jacket 130. Further, during the freezing step, the two shutoff valves V2 and V3 are closed. In this freezing step, first, the supply pipe 111P is connected to the charging port 111, and the supply tube 111T is also attached. Next, the supply valve 111V of the CNF dispersion supply pipe 111P is opened, the CNF dispersion is supplied into the brine solution B cooled to the cooling temperature, and the CNF dispersion is frozen in a short time. The shorter the freezing time of the CNF dispersion, the more preferable. The string-shaped CNF dispersion liquid supplied from the supply port 1110 enters from the liquid level of the brine liquid B and freezes before reaching the filtration member 1022 installed at the bottom. That is, the brine liquid B is stored to such a depth that the CNF dispersion liquid that has entered from the liquid surface of the brine liquid B does not reach the filtration member 1022 as a liquid. Therefore, it is prevented that the eyes of the filtration member 1022 are clogged with the CNF dispersed in the CNF dispersion liquid.

In the freezing step, although the spiral ribbon 122 is an example, the supply tube 111T is passed through the drive shaft 121, and the supply port 1110 is provided on the drive shaft 121. It is also possible to supply a CNF dispersion in the inside. In this case, even if the spiral ribbon 122 is rotationally driven, the amount of the brine liquid B stored is adjusted so that the supply port provided on the drive shaft 121 does not get in contact with the brine liquid B. By supplying the CNF dispersion while rotating the spiral ribbon 122, the CNF dispersion can be frozen while stirring, the CNF dispersion is uniformly cooled, and aggregation is less likely to occur. When the stirring speed is high, the string-shaped CNF dispersion becomes a short string in the brine solution B and is cooled more quickly and uniformly. In this way, by rotating the spiral ribbon 122, the brine solution B can be agitated, the cooling temperature can be maintained, and the frozen product of the supplied CNF dispersion can be crushed and dispersed, but crushing is not necessary. Does not drive the spiral ribbon 122 in rotation.

The supply valve 111V of the supply pipe 111P is closed when the supply of the CNF dispersion liquid is completed.

FIG. 3 is a diagram schematically showing how the CNF dispersion is frozen. Here, for the sake of clarity, the state of freezing that occurs when the CNF dispersion is poured into a thin layer is schematically shown.

FIG. 3A is a schematic diagram showing a state after freezing when the CNF dispersion is slowly frozen (for example, slowly freezing over about 30 minutes), and FIG. 3B is a diagram showing the state after freezing, and FIG. 3B is a rapid freezing of the CNF dispersion. It is a schematic diagram which shows the state after freezing in the case of freezing (for example, freezing in about 5 minutes).

When the CNF dispersion is poured into the brine solution, first, freezing starts from the water portion that occupies most of the brine solution, and ice crystals are formed. When the CNF dispersion is poured into a thin layer and slowly frozen by the above-mentioned conventional shelf-type vacuum freeze-dryer, it schematically becomes a large ice crystal FS as shown in FIG. 3 (a). Since the ice crystal FS represented in white grows significantly, it is considered that the CNF that was present in a wide range is driven by the ice crystal FS and collected in a vertical line represented in black. The black vertical line shown in FIG. 3A corresponds to the concentrated liquid portion RS containing a high concentration of CNF. As described above, in slow freezing, it is considered that water having a property of removing foreign substances during freezing grows slowly and large as pure ice (ice crystal FS), and CNF gathers to form a concentrated liquid portion RS.

On the other hand, in quick freezing, water freezes rapidly. If the state of rapid freezing of water is schematically represented at the same magnification as in FIG. 3 (a), no large ice crystals can be seen, and as shown in FIG. 3 (b), fine ice crystals on the entire surface. Is a schematic diagram in which ice is dispersed. However, if the circled portion is magnified, fine ice crystal FSs are dispersed between the CNFs, as shown in the lower left. It is considered that in the rapid freezing, the ice crystal FS becomes finer and the region of the concentrated liquid portion RS between the ice crystal FS also becomes narrower. If you look at a part of the circled part further, as shown in the square on the right side, fine ice crystal FS are dispersed between the CNFs, while the CNFs are fixed in the state of independent fibers. It has been transformed. Therefore, it is considered that quick freezing is less likely to cause aggregation.

In the freezing step, when an electromagnetic wave is applied, water molecules in the CNF dispersion continue to vibrate and generate heat, while inhibiting the growth of ice crystals and forming fine ice crystals. Therefore, similarly, it is expected that the region of the concentrated liquid portion RS between the ice crystal FSs will be narrowed, the CNFs will be immobilized in the state of independent fibers, and aggregation will be less likely to occur. Further, the CNF fiber itself also vibrates, and it is expected that aggregation is less likely to occur from this point as well. Therefore, also in the freezing step, the electromagnetic wave irradiation may be performed while suppressing the generation of heat by lowering the output as compared with the electromagnetic wave irradiation in the drying step described later.

In the freezing step, the CNF dispersion liquid is supplied into the brine liquid B from a circular supply port 1110 having an opening diameter of 4 mm, which is the tip of the supply tube 111T. The CNF dispersion liquid in the present embodiment has a CNF concentration of about 2% by mass and is gel-like and has strong adhesiveness. Therefore, the shape of the CNF dispersion liquid supplied from the supply port 1110 is a string having a diameter of 4 mm. The string-shaped CNF dispersion can be made into a short string or a long string depending on the supply method.

When the CNF dispersion is frozen in the brine B and the frozen CNF dispersion is generated in the brine B, the separation step (step S3) is carried out. Before starting this separation step, the supply tube 111T may be removed and the spiral ribbon 122 may be rotationally driven. By doing so, the string-shaped frozen CNF dispersion can be finely cut. However, it is necessary not to cut the filtration member 1022 into smaller pieces than the eyes.

Even during this separation step, the heat medium cooled to the set temperature continues to be circulated and supplied to the jacket 130. In the separation step, the brine solution B is separated from the frozen CNF dispersion by filtering the brine B that has produced the frozen CNF dispersion. In the filtration, the two shutoff valves V2 and V3 that have been closed so far are opened, and the brine liquid B is filtered by the own weight of the brine liquid B. In order to shorten the filtration time, pressurized air may be introduced into the main body 100 from the inlet 111. The solid CNF dispersion cannot pass through the eyes of the filter member 1022, and only the liquid brine solution B passes through the eyes of the filter member 1022 and flows into the filtrate receptor 3. The brine solution B recovered in the filtrate receptor 3 can be reused. When the filtration of the brine solution B is completed, the frozen CNF dispersion remains inside the main body 100.

Then, the drying step (step S4) is carried out. In the drying step, the set temperature of the low-temperature constant temperature bath 20 is gradually raised, the temperature of the heat medium supplied to the jacket 130 is gradually raised, and sublimation heat is applied to the frozen CNF dispersion to produce the frozen CNF dispersion. Sublimate. That is, the drying is started with the frozen CNF dispersion frozen, but the temperature of the heat medium, that is, the set temperature of the low temperature constant temperature bath 20 is controlled so that the frozen CNF dispersion does not melt during the drying. .. The program for raising the set temperature of the low temperature constant temperature bath 20 will be described in detail later.

Further, the shutoff valve V2 provided between the filtrate discharge port 1021 and the filtrate receptor 3 is closed, and the shutoff valve V3 provided between the filtrate discharge port 1021 and the exhaust passage 112P is also closed. This drying process is started by starting the driving of the vacuum pump 11. When the vacuum pump 11 is driven, the gas generated inside the main body 100 is sucked. That is, inside the main body 100, vapor is generated by sublimating the frozen CNF dispersion. Further, if even a small amount of brine liquid remains inside the main body 100 after filtration, the gas generated inside the main body 100 includes not only steam but also gas vaporized by the volatile brine liquid B. included. The gas generated inside the main body 100 is drawn into the cold trap 5 through the exhaust passage 112P after the fine powder is removed by the exhaust filter 113. In the cold trap 5, the refrigerant is circulated and supplied from the refrigerator 6, and the gas passing through the cold trap 5 is condensed into ice.

In the present embodiment, the gas generated inside the main body 100 is water vapor, and if a small amount of volatile brine solution that could not be removed by filtration remains, the brine solution may be vaporized. , It is a very small amount and usually does not matter. In addition, a removal device such as deodorization is not required. Further, the ice collected in the cold trap 5 does not have to be treated as waste liquid. In addition, since it is steam rather than exhaust gas mainly composed of a low boiling point solvent, a refrigerator compatible with ultra-low temperature is not required and a general refrigerator is sufficient. From these things, the drying system D1 of this embodiment becomes a low-cost system.

FIG. 4 is a graph showing a program for raising the set temperature of the low temperature constant temperature bath. In FIG. 4, the horizontal axis represents the elapsed time (unit is time), and the vertical axis represents the temperature set in the low temperature constant temperature bath 20.

In the brine liquid B preparation step (step S1), the temperature is set to −30 ° C., and the pressure inside the main body 100 is the same as the atmospheric pressure. The temperature is maintained at −30 ° C. in the freezing step (step S2) and the separation step (step S3), and the pressure inside the main body 100 is the same as the atmospheric pressure. That is, the range of the atmospheric pressure level shown in FIG. 4 corresponds to the brine liquid B preparation-separation step.

In the drying step (step S3), the vacuum pump 11 is started to be driven, and first, low temperature heating is performed for 18 hours. By starting the driving of the vacuum pump 11, the pressure inside the main body 100 is reduced to about 110 Pa, and the pressure inside the main body 100 is maintained at about 110 Pa while the low temperature heating is performed. The low temperature heating is maintained at −30 ° C. for the first 6 hours and 30 minutes before starting the first heating step. In the first temperature raising step, the temperature is gradually raised to the first target temperature. In the present embodiment, the first target temperature is −12 ° C., and the temperature is raised by 3 ° C. every hour 6 times, and the temperature of the low temperature constant temperature bath 20 is finally increased by 18 ° C. In low temperature heating, when the first heating step is completed, the temperature is maintained at -12 ° C. for 6 hours and 30 minutes. When the low temperature heating is completed, the second temperature raising step is started. In the second temperature raising step, the temperature is gradually raised to the second target temperature. In the present embodiment, the second target temperature is 20 ° C., and the temperature is raised by about 3 ° C. every 30 minutes or more 11 times, and the temperature of the low temperature constant temperature bath 20 is finally higher than the first target temperature. It will be 32 ° C higher. When this second temperature rising step is completed, finish drying is started. In finish drying, the set temperature of the low temperature constant temperature bath 20 is maintained at 20 ° C. At the same time as the start of this finish drying, the pressure inside the main body 100 is reduced by controlling the suction amount of the vacuum pump 11 to be increased, and the vacuum pump 11 is dried to a predetermined moisture content.

In the drying step, the spiral ribbon 122 is rotationally driven and the electromagnetic wave is irradiated from the glass window 114. The spiral ribbon 122 starts the rotary drive at the same time as the start of the drying process (the start of the drive of the vacuum pump 11), and continues the rotary drive until the drying step is completed. The rotation speed is a constant speed of 20 rotations / minute. In the irradiation of electromagnetic waves, a microwave of 2450 MHz is irradiated from the glass window 114 to the inside of the main body 100. The timing of the start of irradiation is after the start of the drying step, and in the present embodiment, the timing is the same as the start of the second temperature raising step. When the irradiation of the electromagnetic wave is started, the irradiation is continued intermittently until the drying process is completed. For example, after irradiating for about several minutes, irradiation is repeated for about several minutes at intervals of about several minutes. If electromagnetic waves are irradiated while the internal pressure (vacuum pressure) of the main body 100 is high (vacuum degree is low), the frozen CNF dispersion may melt. Therefore, the timing of starting irradiation is the vacuum pump. It may be the timing to increase the suction amount of No. 11 (timing at the same time as the end of the second temperature rising step). Alternatively, the irradiation of the electromagnetic wave may be started at the same time as the start of the drying step, and the irradiation of the electromagnetic wave may be performed while adjusting the output of the electromagnetic wave so that the frozen CNF dispersion does not thaw during the drying. Further, the irradiation period of the electromagnetic wave and the rotation driving period of the spiral ribbon 122 may be completely shifted or partially overlapped with each other.

In the drying step of the present embodiment, since the drying is started while the CNF dispersion is frozen, the CNFs are frozen and immobilized, so that the CNFs do not approach each other and aggregation is unlikely to occur. Further, even if agglomeration occurs in the frozen CNF dispersion, it can be expected that the hydrogen bond, which is the main cause of the agglomeration, is broken by irradiating with electromagnetic waves. Furthermore, even if the frozen CNF dispersion melts in the drying step and a liquid is generated, the liquid molecules vibrate due to the electromagnetic waves, and the aggregation of CNF is prevented. Further, in the drying step, by irradiating the frozen CNF dispersion with electromagnetic waves, the ice crystals vibrate, the sublimation speed is increased, and the drying time is shortened. Moreover, by irradiating the electromagnetic wave while rotationally driving the spiral ribbon 122, the electromagnetic wave is irradiated to the CNF dispersion frozen product while directly moving the CNF dispersion frozen product, and the electromagnetic wave is the CNF dispersion frozen product. Is uniformly irradiated to the CNF dispersion, and various actions obtained by irradiating the electromagnetic wave are evenly applied to the frozen CNF dispersion. Further, by moving the frozen CNF dispersion, the heat of sublimation is uniformly applied to the frozen CNF dispersion, and the drying time is further shortened.

Completion of the drying step is confirmed by the fact that the temperature or pressure inside the main body 100 becomes lower than the control value, or the state of equilibrium is reached, or the cooling temperature of the cold trap 5 drops, and at the end of the drying step. , The vacuum pump 11 and the refrigerator 6 are stopped. In this way, the frozen CNF dispersion is dried, and the dried CNF remains inside the main body 100.

Finally, a take-out step (step S5) is carried out, and the dried product of CNF is taken out from the inside of the main body 100. In this extraction step, the inside of the main body 100 is returned to atmospheric pressure, the discharge lid 140 that has blocked the discharge port 1001 is opened, and the dried product of CNF is taken out from the discharge port 1001.

FIG. 5 is a diagram showing a modified example of the container shown in FIG. 1, and components (not shown) are the same as those in FIG. In the following description, the components having the same names as the components described so far will be described with the same reference numerals.

FIG. 5 shows a main body 100, a stirring blade 125, and a jacket 130 constituting the container 10. In FIG. 5, the peripheral wall 100a of the main body 100 is shown, and the jacket 130 is arranged outside the peripheral wall 100a. Further, in the container 10 shown in FIG. 5, the upper lid 110 and the input port 111, the exhaust port 112, the exhaust filter 113, and the glass window 114 provided in the upper lid 110 are not shown, but FIG. Similar to the container 10 shown in FIG. 5, the container 10 shown in FIG. 5 is provided with these components.

FIG. 5 shows a cross section of the main body 100 in the vertical direction so that the inside of the main body 100 of the container 10 can be seen. The container 10 of this modified example is provided with a stirring blade 125 instead of the spiral ribbon 122 shown in FIG. The stirring blade 125 shown in FIG. 5 has a paddle shape, and a blade plate-shaped resin paddle member 127 is attached to a tip portion of a metal arm 126 radially protruding from a drive shaft 121 by a bolt 128 to form a blade plate. It is fixed so that the surface faces horizontally (the peak faces vertically). That is, the surface of the blade plate is fixed so as to be vertical. In addition, not limited to such a direction, the surface may be inclined with respect to the rotation direction so that the frozen CNF dispersion liquid is scraped upward along the surface. The outer peripheral edge 1271 of the resin paddle member 127 facing the inner surface of the peripheral wall 100a of the container 10 has a shape inclined along the inner surface at a predetermined distance (see the interval L1 in FIG. 5) from the inner surface thereof. The metal arm 126 projects from the drive shaft 121 so as to face 180 degrees at the same height position. That is, two resin paddle members 127 are provided at the same height position. In addition, three or more resin paddle members 127 may be provided at intervals in the rotation direction.

Further, when viewed in the height direction, the resin paddle member 127 is provided so as to be offset by 90 degrees in the rotation direction. In FIG. 5, the top resin paddle member 127 is located on each of the left and right sides, and the resin paddle member 127 below it is located on the front side and the back side (not shown) of the paper surface, respectively, and further below. The resin paddle member 127 is located on each of the left and right sides. In this way, by arranging the resin paddle members 127 at different height positions adjacent to each other in the vertical direction so as to be displaced in the rotational direction, the object to be agitated, that is, the frozen CNF dispersion liquid in the above-described embodiment is the agitated blade. It is possible to prevent it from going around with 125.

Further, the resin paddle member 127 slightly overlaps in the vertical direction. That is, the height position of the upper edge of the resin paddle member 127 below it is higher than the height position of the lower edge of the resin paddle member 127 on the top (see the interval L2 in FIG. 5). Further, the vertical distance L3 of the metal arm 126 becomes narrower toward the lower side. The area and shape of the resin paddle member 127 may be appropriately selected so that the uniformity of stirring in the main body 100 can be obtained. In particular, the lowermost resin paddle member 127 is close to the bottom surface 100B of the main body 100 and has a drive shaft as shown in FIG. 5 in order to reduce the dead space that tends to occur at the bottom of the main body 100 as much as possible. The shape extends beyond the lower end 121B of 121 and extends downward.

The spiral ribbon 122 shown in FIG. 1 is entirely made of resin, but it is also conceivable that the entire spiral ribbon 122 is made of metal. Both the container 10 in FIG. 1 and the container 10 shown in FIG. 5 have an inner peripheral surface made of metal. For this reason, if the entire spiral ribbon 122 is made of metal, the distance between the inner peripheral surface of the container 10 and the outer peripheral edge of the spiral ribbon 122 will be close to each other, and this distance will be obtained when electromagnetic waves are applied. There is a risk of discharge. When the spiral ribbon 122 is made of metal, by widening this interval, it is possible to suppress the discharge that may occur at this interval when irradiated with electromagnetic waves. On the other hand, in the stirring blade 125 shown in FIG. 5, the distance between the metals is the distance between the tip of the metal arm 126 and the inner peripheral surface of the container 10, and this distance is wide and it is easy to suppress the generation of electric discharge. That is, the outer peripheral edge 1271 of the resin paddle member 127 can be arranged near the inner peripheral surface of the container 10, and the distance between the metal portion of the stirring blade 125 and the inner peripheral surface of the container 10 without reducing the stirring capacity. Can be taken widely. Moreover, by replacing the metal arm 126 with one having a different length, the distance between the metal part of the stirring blade 125 and the inner peripheral surface of the container 10 (the distance between the metals) can be adjusted, and the distance adjustment can be performed. It's easy. Further, it is preferable that the distance between the outer peripheral edge of the stirring blade 125 and the inner peripheral surface of the container 10 can be adjusted not only to suppress the discharge but also to adjust the stirring capacity. While it is difficult to adjust the spacing with the spiral ribbon 122, with the resin paddle member 127, the spacing can be adjusted by changing the bolt fixing position to the metal arm 126, so that the spacing can be adjusted. Is easy, and it is not necessary to have a manufacturing dimensional accuracy as high as the spiral ribbon 122.

Examples of the resin used for the resin paddle member 127 include engineering plastics and FRP. Further, the metal arm 126 and the bolt 128 may be configured to be replaced with those made of resin (for example, engineering plastic, FRP, etc.) and fixed to the drive shaft 121 by an appropriate means.

FIG. 6 is a system diagram of the drying system of the second embodiment.

The drying system D2 shown in FIG. 6 includes a drying device 7 corresponding to an embodiment of the present invention, a filtrate receptor 3, a seal case 4, a cold trap 5, and a refrigerator 6.

The drying device 7 shown in FIG. 6 includes a container 70, a vacuum pump 11 for depressurizing the inside of the container 70, a low-temperature constant temperature bath 20, a motor 72 for rotationally driving the container 70, and a supply side extending in the horizontal direction and becoming a rotation center. It has a support shaft 731 and a discharge side support shaft 732, a supply side bearing 741 that supports the supply side support shaft 731, and a discharge side bearing 742 that supports the discharge side support shaft 732. The vacuum pump 11 is provided on the downstream side of the drying system D2 shown in FIG. A combination of the low temperature constant temperature bath 20 and the vacuum pump 11 corresponds to an example of the drying means. Further, a sprocket (not shown) is provided on each of the supply side support shaft 731 and the output shaft of the motor 72, and the chain 75 is wound between the sprocket. With this configuration, the container 70 can be turned upside down, continuously rotated in one or both directions, stationary in the middle of rotation, and swung in an appropriate angle range. Of course, during rotation or rocking, the fixed pipe that hinders the movement is removed, and the fixed pipe is connected during the process that requires the fixed pipe. It is also possible to use a flexible piping member instead of the fixed piping to enable swinging or the like in the piped state. When the fixed pipe is removed, the valve provided at the connection portion with the main body 700 side is closed. Further, the container 70 may be subjected to vibration. The detailed operation of the container 70 will be described later.

The container 70 shown in FIG. 6 is an example of the state of the initial posture. The container 70 in the initial posture has a hollow cylindrical main body portion 700 having a tapered upper portion and a lid portion 710 that can open and close the lower end of the main body portion 700. A tip opening 701 is formed at the tapered tip of the main body 700. A shutoff valve V5 is connected to the tip opening 701. In the main body 700 shown in FIG. 6, the same brine solution B as the brine solution B described in the description using FIG. 1 is stored.

A filtrate discharge port 711 is formed in the lower part of the lid portion 710. The conduit connected to the filtrate discharge port 711 is bifurcated, one of which is connected to the filtrate receptor 3. A shutoff valve V6 is provided between the filtrate discharge port 711 and the filtrate receptor 3. Further, a filter support material 720 is provided between the lid portion 710 and the main body portion 700, and the filter 730 is installed on the upper surface of the filter support material 720.

Further, above the container 70 in the initial posture shown in FIG. 6, a pressurizing means 702 for supplying a pressurized gas to the inside of the main body 700 is provided. Further, the container 70 is provided with a jacket 740 so as to cover the internal space of the main body 700. An electromagnetic wave path is formed inside the supply-side support shaft 731. A glass window 700 g is provided on the inner peripheral wall of the main body 700 at a position where the supply side support shaft 731 is connected. Quartz glass is fitted in the glass window 700 g, and the electromagnetic wave that has passed through the inside of the supply side support shaft 731 travels to the inside of the main body 700 through the glass window 700 g. Inside the main body 700, an irradiation path 700p extending from the glass window 700g toward the liquid surface of the brine liquid B is provided, and electromagnetic waves are directed from the tip of the irradiation path 700p toward the liquid surface of the brine liquid B. Is irradiated. The electromagnetic wave emitted here is also the same electromagnetic wave as the electromagnetic wave described in the explanation using FIG.

An outward path 7321 and a return path 7322 are formed inside the discharge side support shaft 732. The tip of the outward path 7321 is arranged in the jacket 740 up to the vicinity of the filter support member 720, and the rear end is connected to the low temperature constant temperature bath 20 by using a rotary joint 732a. Further, the tip of the return path 7322 is also connected to the low temperature constant temperature bath 20 by using the rotary joint 732a, and the rear end is arranged to the vicinity of the shutoff valve V5 in the jacket 740. In the low temperature constant temperature bath 20, the heat medium is kept at a set temperature. This heat medium is also the same heat medium as the heat medium described in the description using FIG. The heat medium is supplied to the jacket 740 through the outward path 7321, then recovered from the jacket 740 through the return path 7322 and returned to the low temperature constant temperature bath 20 and repeats the circulation. By circulating and supplying the heat medium to the jacket 740, the temperature of the main body 700 can be adjusted from the outside and the temperature inside the main body 700 can be adjusted to a desired temperature.

Further, a supply path 7323 (for example, a steel pipe) for supplying the CNF dispersion liquid to be dried to the inside of the main body 700 is formed inside the discharge side support shaft 732.

The CNF dispersion liquid supply path 7323 may be provided at a position (for example, inside the supply side support shaft 731) that is not easily affected by the temperature of the outward path 7321 and the return path 7322 or the jacket 740 through which the heat medium circulates. By doing so, it is possible to prevent freezing in the supply path 7323 when the CNF dispersion liquid is supplied.

The supply port 7324, which is the tip of the CNF dispersion liquid supply path 7323, is open inside the main body 700, and has an opening shape in which the specific surface area, which is the surface area per unit mass of the CNF dispersion liquid, is 0.2 m ² / kg or more. The opening direction is directed to the liquid level of the brine liquid B. Further, the shape of the supply port 7324 is not limited, and the shape of the CNF dispersion liquid supplied into the brine liquid B is spherical, cylindrical, disk-shaped, drop-shaped, spiral, shell-shaped, thin plate-shaped, butterfly-shaped, and so on. It may have a star shape, a thin flake shape, a corrugated shape, a twist shape, a prismatic shape, or the like. Alternatively, the supply port 7324 may be provided with a nozzle capable of spraying the CNF dispersion liquid.

Further, a discharge path 7325 is also formed inside the discharge side support shaft 732. The discharge path 7325 is a path that communicates the inside of the main body 700 with the seal case 4. An exhaust filter 703 is provided inside the main body 700, and the gas that has passed through the exhaust filter 703 enters the discharge path 7325 and reaches the inside of the seal case 4 via the rotary joint 732a. A cold trap 5 is provided on the downstream side of the seal case 4, and a vacuum pump 11 is further installed on the downstream side thereof. The above-mentioned supply path 7323 passes through the discharge path 7325, penetrates a part of the exhaust filter 703 through an appropriate seal structure, and the supply port 7324 faces the inside of the main body 700.

Further, the other of the bifurcated pipelines connected to the filtrate discharge port 711 communicates with the discharge passage 7325 via a shutoff valve V7.

Subsequently, a method for producing a dried product of CNF by drying the CNF dispersion liquid using the drying system D2 shown in FIG. 6 will be described.

First, the brine solution B preparation step (the same step as step S1 shown in FIG. 2) is carried out. In this brine liquid B preparation step, the shutoff valve V5 provided in front of the tip opening 701 in the main body 700 is opened. Next, the brine solution B (here, ethanol) is supplied from the tip opening 701 to the main body 700 whose inside is empty. The shutoff valves V6 and V7 provided downstream of the filtrate discharge port 711 are in a closed state. The brine liquid B is filled to the vicinity where the supply port 7324, the tip opening of the irradiation path 700p, and the exhaust filter 703 are not soaked with the brine liquid B, and the amount of the liquid is not soaked even when the freezing step described later is completed. be. Even if the container 70 in the initial posture is turned upside down, the lid portion 710 is opened to supply the brine liquid B to the inside of the main body portion 700, the lid portion 710 is closed, and then the posture of the container 70 is returned to the initial posture. good. Alternatively, the brine liquid B may be supplied from the supply path 7323 by using the supply path 7323 for supplying the CNF dispersion liquid. When the supply of the brine solution B to the inside of the main body 700 is completed, it is desired that the brine solution B stored inside the main body 700 be kept below the freezing point of the CNF dispersion while keeping the inside of the main body 700 in a sealed state. Cool to the cooling temperature. For this cooling, a set temperature (for example, −30 ° C.) corresponding to the cooling temperature is set in the low temperature constant temperature bath 20, and a heat medium cooled to the set temperature in the low temperature constant temperature tank 20 is circulated and supplied to the jacket 740. It is done in.

The main body 700 is provided with a thermometer (not shown) for measuring the temperature of the brine liquid B stored inside the main body 700, and when the brine liquid B is cooled to the above cooling temperature, a freezing step is performed. (The same step as step S2 shown in FIG. 2) is carried out. In this freezing step, the CNF dispersion is rapidly frozen by immersion in brine. Even during the freezing step, the heat medium cooled to the set temperature continues to be circulated and supplied to the jacket 740. Further, during the freezing step, all of the three shutoff valves V5, V6, V7 and the valve 7021 in the path of the pressurizing means 702 are closed. In the freezing step, the valve 7325 of the CNF dispersion supply path 7323 is opened, the CNF dispersion is supplied into the brine solution B cooled to the cooling temperature, and the CNF dispersion is frozen in a short time. Again, the shorter the freezing time of the CNF dispersion, as described with reference to FIG. 3, the better. The valve 7325 of the supply path 7323 is closed when the supply of the CNF dispersion is finished.

In the freezing step, the CNF dispersion liquid is supplied into the brine liquid B from the circular supply port 7324 having an opening diameter of 2 mm at the tip of the supply path 7323 shown in FIG. The CNF dispersion liquid in the second embodiment also has a CNF concentration of about 2% by mass and is gel-like and has strong adhesiveness. Therefore, the shape of the CNF dispersion liquid supplied from the supply port 7324 is a string having a diameter of 2 mm. The string-shaped CNF dispersion can be made into a short string or a long string by the method of supply or by moving the main body 700.

Therefore, while the CNF dispersion liquid is being supplied, the motor 72 is driven to rotate or swing the container 70 to flow the brine liquid B, thereby increasing the efficiency of heat transfer between the CNF dispersion liquid and the brine liquid B. Is preferable.

FIG. 7 is a diagram showing an aspect of the container while supplying the CNF dispersion liquid.

FIG. 7A is a diagram showing a state in which the CNF dispersion liquid is supplied from the supply port 7324 while rotating the container 70. By rotating the container 70, the brine solution B is moved, and the cooling of the brine solution B and the freezing of the CNF dispersion are promoted. The CNF dispersion liquid may be supplied while the container 70 is intermittently rotated, or the container 70 may be stopped from rotating.

FIG. 7B is a diagram showing how the container 70 is vibrating. Vibration can be generated, for example, by attaching a vibrator to the container 70. The liquid level of the brine liquid B stored in the container 70 shown in FIG. 7B is rippling. FIG. 7B also shows the filter 730 installed on the upper surface of the filter support material 720. In FIG. 7B, the string-shaped CNF dispersion supplied from the supply port (not shown) enters from the liquid surface of the brine liquid B and freezes before reaching the filter 730 at the bottom. That is, the brine liquid B is stored to such a depth that the CNF dispersion liquid that has entered from the liquid surface of the brine liquid B does not reach the filter 730 as a liquid. Therefore, it is prevented that the eyes of the filter 730 are clogged with the CNF dispersed in the CNF dispersion liquid.

FIG. 7C is a diagram showing a state in which the container 70 swings around the supply side support shaft 731 and the discharge side support shaft 732. The container 70 is moving more than the vibration, and in FIG. 7C, the container 70 alternately repeats a state of being tilted to the right side and a state of being tilted to the left side. If the tilt angle of the container 70 is too large due to the relationship with the storage amount of the brine solution B, the distance from the liquid level of the brine solution B to the filter 730 becomes short, and the CNF dispersion reaches the filter 730 before freezing. Therefore, the tilt angle of the container 70 is adjusted within a certain angle.

By rotating, vibrating, or shaking the container 70, the CNF dispersion liquid supplied into the brine liquid B spreads in the brine liquid B without consolidating in one place, and the CNF dispersion liquid and the brine liquid B become The contact area is increased to promote cooling of the CNF dispersion. Since the brine liquid B is also moving, it can be regarded as the relative speed between the brine liquid B and the CNF dispersion liquid, and the faster the relative speed is, the faster the CNF dispersion liquid freezes, which is preferable.

The CNF dispersion liquid supply port 7324 may be moved without moving the container 70, or the CNF dispersion liquid may be added to the brine liquid B by moving both the container 70 and the supply port 7324 to change the relative positional relationship between the two. May be supplied.

FIG. 7D is a diagram showing a container in an inverted posture in which the container 70 in the initial posture is inverted by 180 degrees (upper limit inverted).

In the above-mentioned brine liquid preparation step (the same step as step S1 shown in FIG. 2), the container 70 is changed from the initial posture to the inverted posture shown in FIG. 7 (d), the lid portion 710 is opened to supply the brine liquid B, and then the container 70 is inverted. After cooling the brine liquid B to the above cooling temperature in the posture, the freezing step is carried out. In the inverted position, the filter 730 is arranged above the liquid level of the brine liquid B, and the unfrozen CNF dispersion liquid does not come into contact with the filter 730. Even in this inverted posture, it is preferable to vibrate the container 70 as shown in FIG. 7 (b) or to vibrate the container 70 as shown in FIG. 7 (c). Further, the operation of supplying the CNF dispersion liquid may be performed while continuously rotating the container 70 or intermittently rotating the container 70. During any supply of the CNF dispersion, the filter 730 does not come into contact with the CNF dispersion in the state before the completion of freezing, and the supply port 7324 and the exhaust filter 703 are frozen in a state where they are not immersed in the brine solution B. The process is carried out. The reason why the CNF dispersion liquid is supplied while swinging or rotating the container 70 or while moving the supply port 7324 is to quickly complete the freezing of the CNF dispersion liquid, and to improve the heat transfer efficiency with the brine liquid B. It is an object. It is also for the purpose of widely scattering the CNF dispersion liquid in the brine liquid B without accumulating it in one place. The heat transfer efficiency can be grasped as the relative speed between the brine liquid B and the CNF dispersion liquid in the brine liquid B, and the relative speed is high as long as the brine liquid B is sufficiently heat-removed by the heat medium in the jacket 740. Is more preferable.

When the CNF dispersion is frozen in the brine B and the frozen CNF dispersion is generated in the brine B, the separation step is performed in the initial posture as shown in FIG. 6 (the same step as step S3 shown in FIG. 2). Is carried out. The piping of the pressurizing means 702, which was removed during rotation, vibration, or shaking of the container 70, is connected to the container 70, and the fixed piping connecting the filtrate receiver 3 and the valve V6 is also connected to the container 70. Will be done. Even during this separation step, the heat medium cooled to the set temperature continues to be circulated and supplied to the jacket 740. In the separation step, the brine solution B is separated from the frozen CNF dispersion by filtering the brine B that has produced the frozen CNF dispersion. For filtration, of the three shutoff valves V5, V6, V7 and the valves 7021 in the path of the pressurizing means 702, which had been closed so far, the shutoff valve V6 in front of the filtrate receiver 3 was opened to pressurize as shown in FIG. The valve 7021 of the means 702 path is opened, and pressurized air is introduced into the main body 700. Inside the main body 700, the brine liquid B is pressurized (a pressure greater than 0 and 0.01 MPaG or less is applied), and the brine liquid B is filtered. If necessary, the space below the filter 730 may be depressurized, or filtration may be performed without pressurizing or depressurizing. The frozen CNF dispersion, which is a solid, cannot pass through the eyes of the filter 730, and only the liquid brine B flows through the eyes of the filter 730 into the filtrate receptor 3. The brine solution B recovered in the filtrate receptor 3 can be reused. When the filtration of the brine solution B is completed, the frozen CNF dispersion remains inside the main body 700.

Then, a drying step (the same step as step S4 shown in FIG. 2) is carried out. In the drying step, the set temperature of the low-temperature constant temperature bath 20 is gradually raised, the temperature of the heat medium supplied to the jacket 740 is gradually raised, and sublimation heat is applied to the frozen CNF dispersion to produce the frozen CNF dispersion. Sublimate. That is, the drying is started with the frozen CNF dispersion frozen, but the heating temperature is set so that the frozen CNF dispersion does not melt during the drying. Further, the shutoff valve V6 provided between the filtrate discharge port 711 and the filtrate receptor 3 is closed, and the shutoff valve V7 provided between the filtrate discharge port 711 and the discharge passage 7325 is opened. Further, the vacuum pump 11 is driven to suck the gas generated inside the main body 700. That is, inside the main body 700, vapor is generated by sublimating the frozen CNF dispersion. Further, if even a small amount of brine liquid remains inside the main body 700 after filtration, the gas generated inside the main body 700 includes not only steam but also gas vaporized by the volatile brine liquid B. included. The gas generated inside the main body 700 is drawn into the seal case 4 through the discharge path 7325 after the fine powder is removed by the exhaust filter 703. Further, this gas is also drawn into the seal case 4 from the filtrate discharge port 711 through the discharge path 7325. The gas that has passed through the seal case 4 is drawn into the cold trap 5. In the cold trap 5, the refrigerant is circulated and supplied from the refrigerator 6, and the gas is condensed in the cold trap 5 to become ice.

The gas generated inside the main body 700 is water vapor, and if a small amount of volatile brine solution that could not be removed by filtration remains, the brine solution may be vaporized, but it is a trace amount. Usually it doesn't matter. In addition, a removal device such as deodorization is not required. Furthermore, the recovered ice does not have to be treated as waste liquid. In addition, since it is steam rather than exhaust gas mainly composed of a low boiling point solvent, a refrigerator compatible with ultra-low temperature is not required and a general refrigerator is sufficient. For these reasons, the drying system D2 of the second embodiment is also a low-cost system.

In the drying process, electromagnetic wave irradiation is also performed. The irradiation of electromagnetic waves here is also irradiated with microwaves of 2450 MHz. This microwave is intermittently irradiated from the tip of the irradiation path 700p toward the liquid surface of the brine liquid B through the glass window 700g. Since the timing of the start of electromagnetic wave irradiation is the same as that described in the timing of the start of electromagnetic wave irradiation in the drying step of the drying system D1 shown in FIG. 1, the description thereof is omitted here.

Further, electromagnetic waves may be irradiated while moving the frozen CNF dispersion by moving the container 70 in various embodiments described with reference to FIG. 7. However, in this case, it is necessary to remove the pipe connecting the filtrate discharge port 711 and the filtrate receptor 3.

Completion of the drying process is confirmed by the equilibrium of the temperature or vacuum pressure in the container 70, the decrease in the cooling temperature of the cold trap 5, etc., and at the end of the drying process, the shutoff valve V7 is closed to create a vacuum. Stop the pump 11 and the refrigerator 6. Next, the shutoff valve V5 is opened, and the inside of the container 70 is returned to atmospheric pressure. In this way, the frozen CNF dispersion is dried, and the dried CNF remains inside the main body 700.

Finally, a take-out step (the same step as step S5 shown in FIG. 2) is carried out, and the dried product of CNF is taken out from the inside of the main body 700. In this extraction step, the dried product of CNF may be taken out from the tip opening 701 with the main body 70 in the inverted posture, or the dried product of CNF may be taken out together with the filter 730 by opening the lid portion 710 in the initial posture. ..

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. For example, in the above-described embodiment, the CNF dispersion is dried, but the present invention is not limited to the CNF dispersion, and is also applied to a technique for drying a dispersion in which carbon nanoparticles, metal nanoparticles, ceramic nanoparticles, etc. are dispersed in a liquid. be able to.

Even if the constituent requirements are included only in the description of each of the above-described embodiments, the constituent requirements may be applied to other embodiments.

D1, D2 Drying system 1,7 Drying device 10,70 Container 100,700 Main body 114,700g Glass window 1022 Filtration member 1110, 7324 Supply port 121 Drive shaft 122 Spiral ribbon 123 Drive device 125 Stirring blade 126 Metal arm 127 Resin Paddle member 130 Jacket 730 Filter 72 Motor 11 Vacuum pump 20 Low temperature constant temperature bath 3 Filtration acceptor 5 Cold trap 6 Refrigerator B Bline liquid

Claims (8)

A freezing step of freezing the dispersion liquid in which the object to be treated is dispersed in the liquid to obtain a frozen product,
It has a drying step of starting drying while the frozen product is frozen to obtain a dried product.
A method for producing a dried product, wherein the drying step is a step of irradiating the frozen product with an electromagnetic wave while moving the frozen product to sublimate the frozen product. The freezing step is a step of freezing the dispersion liquid with a brine liquid.
Claim 1 is characterized by having a separation step of separating the brine solution from the frozen product by filtering the brine solution after the freezing step is completed and before the drying step is started. The method for producing a dried product according to the description. The method for producing a dried product according to claim 1 or 2, wherein the freezing step is a step of freezing the dispersion liquid while stirring. One of claims 1 to 3, wherein the freezing step is a step of discharging the dispersion liquid into the brine liquid from a supply port and freezing the discharged dispersion liquid with the brine liquid. The method for producing a dried product according to the above item. A container for storing the frozen material in which the dispersion liquid in which the object to be treated is dispersed in the liquid is frozen,
A drying means for starting drying while the frozen product stored in the container is frozen, and a drying means.
A frozen material moving part that moves the frozen material dried by the drying means in the container, and
A drying device including an irradiation unit that irradiates the frozen material dried by the drying means with an electromagnetic wave. The drying device according to claim 5, wherein the irradiation unit irradiates the frozen material in a state of moving in the container with an electromagnetic wave. The drying device according to claim 5 or 6, wherein the frozen material moving portion moves the frozen material stored in the container by moving the container. The drying apparatus according to claim 5 or 6, wherein the frozen material moving portion stirs the frozen material stored in the container.

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