JP7274341B2 - Apparatus and method for producing chemically modified biomass nanofiber dispersion, and method for producing chemically modified biomass nanofiber - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus and method for producing a chemically modified biomass nanofiber dispersion, and a method for producing chemically modified biomass nanofibers.

There are many chemically modified biomass nanofibers in the world. Conventionally, various methods for producing such biomass nanofibers have been developed.
For example, Patent Document 1 discloses a step of swelling and/or partially dissolving a cellulosic material or chitin material using a mixed solvent containing an ionic liquid and an organic solvent, and esterifying the swollen and/or partially dissolved component. , etherification or simultaneous esterification and etherification, and a washing step for removing ionic liquids and the like are disclosed.

In addition, Patent Document 2 discloses a method in which a step of fibrillating a cellulose raw material in a solution containing an ionic liquid and a step of chemically modifying the hydroxyl groups of cellulose nanofibers using a modifier are performed in one step. ing.
Further, Patent Document 3 discloses a method of defibrating by mixing a cellulose-containing raw material with a treatment liquid composed of an ionic liquid and a diluent.
Further, Patent Document 4 discloses a method of producing a composite of hydrophobic cellulose nanofibers and a thermoplastic resin by acetylating lignocellulose and then kneading it with a thermoplastic resin.

Patent No. 5676860 JP 2013-44076 A JP 2013-155445 A Patent No. 6091589

The invention described in Patent Document 1 involves a swelling and/or partial dissolution step using an ionic liquid, a fibrillation step using a homogenizer, and finally an acetylation step. In addition, since the chemical modification process and the fibrillation process are separated, the total processing time is lengthened.
In the invention described in Patent Document 2, although the swelling step with the ionic liquid and the acetylation step are performed at once, the fibers are washed and recovered after the reaction is completed, and finally the fibrillation step is performed using a homogenizer. The number of processes is large. Furthermore, there were variations in accuracy.
The invention described in Patent Literature 3 aims at simply producing nanofibers, not chemically modifying them.
Moreover, the inventions described in Patent Documents 1 to 3 use a special reagent called an ionic liquid, and are not general-purpose production methods.
The invention described in Patent Document 4 is effective only for forming a composite with a thermoplastic resin, so its application is limited. In addition, since the obtained cellulose nanofibers have a relatively large fiber diameter, it is not suitable for the case where finer cellulose nanofibers are required.

The present invention aims to provide an apparatus and method for producing a chemically modified biomass nanofiber dispersion, and a method for producing chemically modified biomass nanofibers, which can simultaneously perform a chemical modification step and a fibrillation step of biomass in one step. Make it an issue.

In order to solve the above-mentioned problems, an apparatus for producing a chemically modified biomass nanofiber dispersion liquid (hereinafter referred to as a production apparatus as appropriate) according to the present invention includes a raw material tank, biomass put into the raw material tank, and the biomass A low-pressure pipe for circulating a dispersion fluid containing a reagent for modification, a feed pump for supplying the dispersion fluid input to the raw material tank to the low-pressure pipe, and the dispersion fluid supplied to the low-pressure pipe. A pressure intensifier that pressurizes, a high-pressure pipe through which the dispersion fluid pressurized by the pressure intensifier flows, and the dispersion fluid supplied to the high-pressure pipe collide with a collision hard body by high-pressure injection processing, or a collision chamber for colliding with each other; and a heat exchanger for cooling the dispersed fluid collided in the collision chamber, wherein the low-pressure piping connects the reaction low-pressure piping between the collision chamber and the heat exchanger. The high-pressure piping includes reaction high-pressure piping between the intensifier and the collision chamber.

In addition, the method for producing a chemically modified biomass nanofiber dispersion according to the present invention (hereinafter referred to as a method for producing a dispersion as appropriate) comprises dispersing a dispersion fluid containing biomass and a reagent for chemically modifying the biomass under high pressure. The biomass chemical modification step and fibrillation step are simultaneously performed in one step by colliding against the collision hard body or colliding with each other by jetting.

Further, the method for producing chemically modified biomass nanofibers according to the present invention (hereinafter referred to as a method for producing nanofibers as appropriate) is a chemically modified biomass nanofiber produced by the method for producing a chemically modified biomass nanofiber dispersion described above. It is characterized by removing the unreacted reagent in the dispersion and recovering the chemically modified biomass nanofibers.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an apparatus and method for producing a chemically modified biomass nanofiber dispersion, and a method for producing chemically modified biomass nanofibers, in which the biomass chemical modification step and fibrillation step can be performed simultaneously in one step. .

Schematic schematic diagram of a chemically modified biomass nanofiber dispersion manufacturing apparatus according to an embodiment Flowchart of a method for producing a chemically modified biomass nanofiber dispersion according to an embodiment Graph showing the relationship between the number of treatments, degree of substitution (DS), and temperature change in Examples 1 and 2 FE-SEM observation image of the sample obtained in Example 1 FE-SEM observation image of the sample obtained in Example 2 SPM observation image of the sample obtained in Example 3 SPM observation image of the sample obtained in Example 4 SPM observation image of the sample obtained in Example 5 FE-SEM observation image of 1pass sample obtained in Example 1 FE-SEM observation image of the 6pass sample obtained in Example 1 FE-SEM observation image of the 10pass sample obtained in Example 1 FE-SEM observation image of the 14pass sample obtained in Example 1 FE-SEM observation image of the 22-pass sample obtained in Example 1 FE-SEM observation image of the 26-pass sample obtained in Example 1 FE-SEM observation image of 1pass sample obtained in Example 2 FE-SEM observation image of the 6pass sample obtained in Example 2 FE-SEM observation image of the 10pass sample obtained in Example 2 FE-SEM observation image of the 14pass sample obtained in Example 2 FE-SEM observation image of the 22-pass sample obtained in Example 2

Embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
In addition, in each figure, the same code|symbol is attached|subjected about a common component and a similar component, and those overlapping description is abbreviate|omitted suitably.

<Manufacturing equipment>
First, an apparatus for producing a chemically modified biomass nanofiber dispersion will be described.
A manufacturing apparatus according to an embodiment of the present invention will be described in detail with appropriate reference to FIG. FIG. 1 is a schematic diagram of an apparatus for producing a chemically modified biomass nanofiber dispersion liquid according to an embodiment of the present invention.

The manufacturing apparatus 100 includes a raw material tank 10, a liquid supply pump 20, a hydraulic pressure generation and control unit 30, a pressure booster 40, a check valve 50, a collision chamber 60, a heat exchanger 70, a low pressure pipe 80, A high-pressure pipe 90 is provided.

The raw material tank 10 is for charging a raw material, specifically, a dispersing fluid containing biomass and a reagent for chemically modifying the biomass.
The liquid supply pump 20 supplies the dispersion fluid introduced into the raw material tank 10 to the low-pressure pipe 80 .
The hydraulic pressure generation and control section 30 drives and controls the pressure booster 40 by hydraulic pressure.
The pressure booster 40 pressurizes the dispersion fluid supplied to the low pressure pipe 80 . Two pressure boosters 40 are provided here, and each pressure booster 40 is connected to a check valve 50 .
The check valve 50 prevents the dispersion fluid from flowing in only one direction and from flowing in the other direction.

The collision chamber 60 causes the dispersion fluid supplied to the high-pressure pipe 90 to collide with the collision hard body or with each other by high-pressure jetting. The impingement chamber 60 contains an orifice nozzle 61 . The dispersion fluid is jetted from orifice nozzles 61 . The diameter of the orifice nozzle 61 is, for example, 0.08-0.8 mm. If the diameter is 0.08 mm or more, the orifice nozzle 61 is less likely to be clogged with the raw material, and the dispersion fluid can be easily jetted. On the other hand, if the diameter is 0.8 mm or less, it becomes easier to control the pressure in the injection of the dispersion fluid within a desired range.
The heat exchanger 70 cools the dispersed fluid impinged in the impingement chamber 60 .

The low-pressure pipe 80 circulates the dispersion fluid introduced into the raw material tank 10 . Also, the low-pressure pipe 80 circulates the dispersion fluid that has been collided in the collision chamber 60 .
The low-pressure pipe 80 connects the liquid supply pump 20 and the pressure booster 40 , the collision chamber 60 and the heat exchanger 70 , and the heat exchanger 70 and the raw material tank 10 . The liquid supply pump 20 and the pressure booster 40 are connected by a low-pressure pipe 80 via a check valve 50 . The low pressure piping 80 includes a reaction low pressure piping 81 as part of the low pressure piping 80 between the collision chamber 60 and the heat exchanger 70 .
The reaction low-pressure pipe 81 is for promoting the chemical reaction between the biomass and the reagent.

The high-pressure pipe 90 circulates the dispersion fluid pressurized by the pressure booster 40 .
A high-pressure pipe 90 connects the intensifier 40 and the collision chamber 60 . The pressure intensifier 40 and the collision chamber 60 are connected by a high pressure pipe 90 via a check valve 50 . The high pressure piping 90 includes a reaction high pressure piping 91 as part of the high pressure piping 90 between the intensifier 40 and the collision chamber 60 .
The high-pressure pipe 90 is for promoting the chemical reaction between biomass and reagents.

The reaction low-pressure pipe 81 and the reaction high-pressure pipe 91 are formed in a spiral shape. By making the reaction low-pressure pipe 81 and the reaction high-pressure pipe 91 spiral, the required length can be secured with a small installation area.
There are no restrictions on the length, thickness, angle, shape, state of surface treatment, size (spiral circle diameter), etc., of the reaction low-pressure pipe 81 and the reaction high-pressure pipe 91 . However, by lengthening the distance through which the dispersion fluid passes, the reaction low-pressure pipe 81 and the reaction high-pressure pipe 91 ensure time for the biomass in the dispersion fluid to be chemically modified by the reagent, as will be described later. be able to.
The reaction low-pressure pipe 81 and the reaction high-pressure pipe 91 are not limited to a spiral shape, and may be, for example, a folded pipe shape. Moreover, when the installation area is not taken into consideration, it may be linear.

The reaction low-pressure pipe 81 and the reaction high-pressure pipe 91 are provided so as to be easily detachable. That is, the reaction low-pressure pipe 81 can be easily attached and detached at the portion indicated by symbol A in FIG. Also, the reaction high-pressure pipe 91 can be easily attached and detached at the portion indicated by symbol B in FIG. Therefore, depending on the content of chemical modification, the type of reagent, etc., the length, thickness, angle, shape, state of surface treatment, size (spiral circle diameter), etc. of the low-pressure reaction pipe 81 and the high-pressure reaction pipe 91 can be easily changed. can be changed or selected as appropriate. However, the reaction low-pressure pipe 81 may be integrated with the other low-pressure pipe 80 . Similarly, the reaction high-pressure pipe 91 may be integrated with another high-pressure pipe 90 .

The length of the reaction low-pressure pipe 81 and the reaction high-pressure pipe 91 is preferably 50 to 20000 mm. If the length is 50 mm or more, it becomes easier to promote the chemical reaction between the biomass and the reagent. Moreover, it becomes easy to process parts and to install piping. On the other hand, if the length is 20000 mm or less, the size of the device can be reduced. Moreover, it becomes easy to process parts and to install piping. The length of the reaction high-pressure pipe 91 and the reaction low-pressure pipe 81 is particularly 100 mm from the viewpoint of facilitating the chemical reaction between the biomass and the reagent, and from the viewpoint of easiness in processing parts and easiness in mounting. The above is preferable.

<Operation of manufacturing equipment>
Next, an outline of the operation of the manufacturing apparatus 100 will be described.
The dispersion fluid introduced into the raw material tank 10 is supplied to the low-pressure pipe 80 by the liquid supply pump 20 . The dispersion fluid supplied to the low-pressure pipe 80 is pressurized by the pressure booster 40 and supplied to the high-pressure pipe 90 . When the dispersing fluid passes through the reaction high-pressure pipe 91 of the high-pressure pipe 90, the chemical reaction between the biomass in the dispersing fluid and the reagent is promoted, and the biomass is chemically modified by the reagent. After that, the dispersion fluid is supplied to the collision chamber 60, and is injected at high pressure by the collision chamber 60, so that the biomass in the dispersion fluid is chemically modified with the reagent and defibrated by the collision energy. After that, the dispersion fluid is supplied to the low-pressure pipe 80, and when passing through the reaction low-pressure pipe 81 of the low-pressure pipe 80, the chemical reaction between the biomass in the dispersion fluid and the reagent is promoted, and the biomass is chemically modified by the reagent. . The dispersion fluid is then supplied to heat exchanger 70 to be cooled. The dispersion fluid (chemically modified biomass nanofiber dispersion) obtained in this way is recovered, or, if necessary, is put into the raw material tank 10 again and circulated.

<Method for producing dispersion>
Next, an example of a method for producing a chemically modified biomass nanofiber dispersion will be described.
A method for producing a dispersion liquid according to an embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 2 is a flow chart of a method for producing a chemically modified biomass nanofiber dispersion according to an embodiment.
The method for producing a dispersion liquid according to the present embodiment can be performed using the production apparatus 100 described above. However, a device other than the manufacturing device 100 may be used.

The dispersion manufacturing method includes a step S101 of preparing a dispersion fluid, a step S102 of chemically modifying and fibrillating, and a step S103 of cooling the dispersion fluid, which are performed in this order. After the step S103 of cooling the dispersion fluid, it is determined whether or not to repeat the high-pressure injection treatment (the step of chemical modification and fibrillation) (S104), and if necessary, steps S102 and S103 are repeated.

[Step of preparing dispersion fluid]
The step S101 of preparing a dispersing fluid is a step of preparing a dispersing fluid containing biomass and a reagent for chemically modifying the biomass.
Examples of biomass include cellulose (powdered cellulose and pulp), chitin, chitosan, and the like.
Reagents for chemically modifying biomass vary depending on the desired chemical reaction, but acetic anhydride, acetyl chloride, and the like are exemplified for acetylation, which is a typical esterification.

In addition, a dispersant or catalyst may be mixed. Dispersants include, for example, DMF (N,N-dimethylformamide). Examples of catalysts include DMAP (4-(dimethylamino)pyridine, 4-dimethylaminopyridine, etc.), TEA (triethylamine), pyridine and the like.

The ratio of biomass to reagent is not particularly limited, and may be appropriately adjusted depending on the details of chemical modification, the type of reagent, and the like. One example is adding 1.0 to 20.0 equivalents of the reagent to the biomass.

[Step of chemical modification and fibrillation]
In the chemical modification and fibrillation step S102, a dispersion fluid containing biomass and a reagent for chemically modifying the biomass is collided with a collision hard body or with each other by high-pressure jetting, thereby This is a process in which the chemical modification process and the fibrillation process are performed simultaneously in one process.

In this step S102, the dispersion fluid is sent from the raw material tank 10 of the manufacturing apparatus 100 to the pressure booster 40, pressurized by the pressure booster 40, circulated through the high pressure pipe 90, and injected at high pressure from the collision chamber 60 to form a hard body for collision. After colliding or colliding with each other, the reaction low-pressure pipe 81 is circulated and sent to the heat exchanger 70 .

By using the manufacturing apparatus 100 described above, the manufacturing apparatus 100 serves as a chemical reaction reactor, and chemical modification and fibrillation can be performed simultaneously in one step. Chemical modification does not occur instantaneously, but is correlated with time. That is, chemical modification proceeds gradually. There is a correlation with the number of collisions caused by high-pressure jetting for fibrillation. Therefore, the degree of chemical modification and the degree of fibrillation change depending on the time spent and the number of times of collision. Moreover, in the esterification and etherification of cellulose, the reaction is promoted by raising the temperature during the reaction. In other words, it is important to find and set reaction conditions (pressure, treatment time, etc.) that achieve the desired degree of chemical modification (degree of substitution) and degree of fibrillation (fiber diameter). Therefore, the length and diameter of the reaction high-pressure pipe 91, the pressure during the high-pressure injection process, and the like are appropriately set according to the purpose.

The high-pressure injection treatment is preferably performed at a pressure of 100-245 MPa. If the pressure is 100 MPa or higher, high-pressure injection can be easily performed. On the other hand, if the pressure is 245 MPa or less, the burden on the manufacturing apparatus 100 can be reduced.
The dispersion fluid may collide with a collision hard body provided in the collision chamber 60, or the dispersion fluids may collide with each other. Examples of the collision hard body include cemented carbides mainly made of tungsten carbide, and hard ceramics such as silicon nitride, zirconia, and alumina.

In addition, after the high-pressure injection treatment, the reaction low-pressure pipe 81 can promote the chemical reaction between the biomass and the reagent, and defibration.
The chemical modification and fibrillation of biomass are performed through the chemical modification and fibrillation step S102. Chemical modification can be further promoted when passing through the low-pressure pipe 81 .
The present invention is more effective when a catalyst having a high reaction promoting effect such as DMAP is used as the catalyst mixed with the dispersion fluid.
Types of chemical modification include esterification and etherification.

[Step of cooling dispersion fluid]
The step S103 of cooling the dispersion fluid is a step of cooling the dispersion fluid that has undergone the high-pressure injection process. Cooling of the dispersing fluid can be provided by a heat exchanger 70 .
During cooling by the heat exchanger 70, the flow rate and temperature of cooling water flowing through the heat exchanger 70 are controlled. The method of supplying the cooling water is not particularly limited, and examples thereof include the use of free-flowing water from a tap and the use of a chiller. Moreover, the structure of the heat exchanger 70 is not limited, and examples thereof include a plate type and a multi-tube type.

A chemically modified biomass nanofiber dispersion is produced through these steps S101 to S103. The chemically modified biomass nanofiber dispersion is determined whether to repeat the high-pressure injection process (step S104), and if necessary, is put into the raw material tank 10 again, and steps S102 and S103 are repeated. Repeating may be performed multiple times. Thereby, the degree of chemical modification and the degree of fibrillation can be adjusted.

Chemical reactions are greatly affected by temperature. Therefore, temperature control of the dispersing fluid is important. Generally, the higher the temperature, the faster the chemical reaction, so the higher the temperature of the dispersing fluid, the better. However, considering the load on the manufacturing apparatus 100, the heat resistance of biomass, and the energy consumption due to heating, the temperature from the raw material tank 10 to the pressure booster 40 is preferably 10 to 80.degree. In other words, it is preferable to control the temperature of the dispersion fluid in the raw material tank 10 at 10 to 80.degree. Also, the temperature in the high-pressure pipe 90 is preferably 10 to 150.degree. That is, the dispersion fluid may be heated by heating the surface of the high-pressure pipe 90, and it is preferable to control the temperature of the dispersion fluid in the high-pressure pipe 90 at 10 to 150.degree. Thereafter, the temperature of the dispersion fluid in the reaction low-pressure pipe 81 rises by about 50° C. from the temperature of the dispersion fluid before collision when it collides with the collision hard body or collides with each other in the collision chamber 60. is about +50° C. of the dispersion fluid in the high-pressure pipe 90 . Therefore, the temperature of the dispersion fluid in the reaction low-pressure pipe 81 is preferably 60 to 200.degree. Of course, the surface of the reaction low-pressure pipe 81 may be heated to further heat the dispersed fluid.
The temperature of the dispersion fluid in the raw material tank 10 can be controlled by sending it from the reaction low-pressure pipe 81 to the heat exchanger 70 and cooling it in the heat exchanger 70 to control the temperature of the dispersion fluid to 10 to 80°C.

The temperature of the dispersion fluid is controlled by monitoring the liquid temperature of the dispersion fluid in the raw material tank 10, the high-pressure pipe 90, and the reaction low-pressure pipe 81, if necessary. The temperature of the dispersion fluid is controlled not only by controlling the cooling by the heat exchanger 70 but also by heating the surfaces of the reaction low-pressure pipe 81 and the high-pressure pipe 90 . The method for heating the surfaces of the reaction low-pressure pipe 81 and the high-pressure pipe 90 is not particularly limited. For example, putting it in. In addition to controlling the temperature of the heater itself, it is also possible to directly measure the temperature of the dispersion fluid using a thermocouple and control the temperature of the heater.

<Method for producing nanofiber>
The nanofiber production method is to remove unreacted reagents in the chemically modified biomass nanofiber dispersion produced by the chemically modified biomass nanofiber dispersion production method described above and recover the chemically modified biomass nanofibers. be.

Methods for removing unreacted reagents are not particularly limited, and include, for example, pressure filtration, vacuum filtration, centrifugal filtration and the like.
Specifically, for example, first, a dispersion is added to pure water to precipitate chemically modified biomass nanofibers. Next, pure water is removed by filtration, and pure water washing is repeated to obtain chemically modified biomass nanofibers.

When the chemically modified biomass nanofibers are cellulose nanofibers (CNF), the preferred range of the degree of substitution is 0.05 to 2.5 from the viewpoint of the degree of hydrophobicity imparted and the retention of the cellulose type I crystal structure. , more preferably 0.1 to 1.8.
Moreover, the preferred range of the average fiber diameter of CNF is 3 to 1000 nm from the viewpoint of functionality and wide application range. More preferably, it is 3 to 100 nm.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these.
As an example, an example of chemical modification of acetylation is shown. The chemical modification is not limited to acetylation, and a wide range of chemical modification of cellulose, mainly esterification and etherification of cellulose, can be dealt with.
As the basic equipment for the chemical modification and CNF formation (defibration) steps of Examples 1 to 5 below, a manufacturing equipment (manufactured by Sugino Machine Co., Ltd.) according to the manufacturing equipment described in the embodiment was used. In the manufacturing apparatus, the lengths of the high-pressure reaction pipe and the low-pressure reaction pipe can be easily changed. Also, the samples obtained in Examples 1 to 5 and Comparative Example 1 were washed by the washing method described in Example 6 and then recovered.

[Embodiment 1 (normal circuit, no temperature control)]
Cellulose powder was dispersed in dimethylformamide (DMF) to a concentration of 2% by mass, 10 equivalents of acetic anhydride was added to cellulose (one molecule of glucose) as an acetylating agent, and DMAP (4-(dimethylamino)pyridine, 4-dimethylaminopyridine) and TEA (triethylamine) were added in an amount of 0.1 equivalent to cellulose (one molecule of glucose) to prepare a sample. The cellulose/DMF dispersion was subjected to high-pressure treatment using this production apparatus under the following conditions to simultaneously perform acetylation and CNF conversion (fibrillation).
In Example 1, after processing 14 passes (collision 14 times), processing was further performed up to 26 passes.

Total charged amount (dispersion fluid amount): 3516.4 g (sampling at 1, 6, 10, 14, 18, 22 passes, about 250 g each)
Processing pressure: 200 MPa
Processing times: 14 times (about 39 min)
High pressure pipe for reaction: 105 mm
Low pressure pipe for reaction: 300 mm
Pre-collision reaction liquid temperature: 22-48°C
Post-collision reaction liquid temperature: Pre-collision reaction liquid temperature + 50°C

"Example 2 (extension of high pressure piping for reaction, no temperature control)"
Cellulose powder was dispersed in dimethylformamide (DMF) to a concentration of 2% by mass, 10 equivalents of acetic anhydride was added to cellulose (one molecule of glucose) as an acetylating agent, and DMAP (4-(dimethylamino)pyridine, 4-dimethylaminopyridine) and TEA (triethylamine) were added in an amount of 0.1 equivalent to cellulose (one molecule of glucose) to prepare a sample. The cellulose/DMF dispersion was subjected to high-pressure treatment using this production apparatus under the following conditions to simultaneously perform acetylation and CNF conversion (fibrillation).
In Example 2, after processing 14 passes (collision 14 times), processing was further performed up to 22 passes.

Total charged amount (dispersion fluid amount): 1758.3 g (sampling at 1, 6, 10, 14, 18 passes, about 150 g each)
Processing pressure: 200 MPa
Processing times: 14 times (about 21 min)
High pressure pipe for reaction: 5684mm
Low pressure pipe for reaction: 300mm
Pre-collision reaction liquid temperature: 24-59°C
Post-collision reaction liquid temperature: Pre-collision reaction liquid temperature + 50°C

[Example 3 (catalyst change, temperature control)]
Cellulose powder was dispersed in dimethylformamide (DMF) to a concentration of 2% by mass, 10 equivalents of acetic anhydride was added to cellulose (1 molecule of glucose) as an acetylating agent, and TEA (triethylamine) was added to cellulose (1 molecule of glucose) as a catalyst. ) was added to prepare a sample. The cellulose/DMF dispersion was subjected to high-pressure treatment using this production apparatus under the following conditions to simultaneously perform acetylation and CNF conversion (fibrillation).

Processing pressure: 200 MPa
Processing time: 40min
High pressure pipe for reaction: 105 mm
Low pressure pipe for reaction: 300mm
Pre-collision reaction liquid temperature: 35-50°C
Post-collision reaction liquid temperature: Pre-collision reaction liquid temperature + 50°C

[Example 4 (catalyst change, temperature control)]
Cellulose powder was dispersed in dimethylformamide (DMF) to a concentration of 2% by mass, 10 equivalents of acetic anhydride was added to cellulose (1 molecule of glucose) as an acetylating agent, and TEA (triethylamine) was added to cellulose (1 molecule of glucose) as a catalyst. ) was added to prepare a sample. The cellulose/DMF dispersion was subjected to high-pressure treatment using this production apparatus under the following conditions to simultaneously perform acetylation and CNF conversion (fibrillation).

Processing pressure: 200 MPa
Processing time: 40min
High pressure pipe for reaction: 5684 mm
Low pressure pipe for reaction: 300mm
Pre-collision reaction liquid temperature: 35-50°C
Post-collision reaction liquid temperature: Pre-collision reaction liquid temperature + 50°C

[Example 5 (no catalyst, temperature control)]
A sample was prepared by dispersing cellulose powder in dimethylformamide (DMF) to a concentration of 2% by mass, and adding 10 equivalents of acetic anhydride as an acetylating agent to cellulose (one molecule of glucose). The cellulose/DMF dispersion was subjected to high-pressure treatment using this production apparatus under the following conditions to simultaneously perform acetylation and CNF conversion (fibrillation).

Processing pressure: 200 MPa
Processing time: 40min
High pressure pipe for reaction: 5684mm
Low pressure pipe for reaction: 300mm
Pre-collision reaction liquid temperature: 35-50°C
Post-collision reaction liquid temperature: Pre-collision reaction liquid temperature + 50°C

[Comparative Example 1 (acetylation in a beaker)]
Cellulose powder was dispersed in dimethylformamide (DMF) to a concentration of 2% by mass, 10 equivalents of acetic anhydride was added to cellulose (1 molecule of glucose) as an acetylating agent, and TEA (triethylamine) was added to cellulose (1 molecule of glucose) as a catalyst. ) was added to prepare a sample. The cellulose/DMF dispersion was stirred under the following conditions to carry out acetylation.

Stirring speed: 150 rpm
Stirring time: 40min
Reaction liquid temperature: 40°C

[Example 6 (washing method)]
After the treatment by this production apparatus or after the treatment by stirring, the treated liquid was added to pure water to precipitate acetylated CNF. Pure water was removed by filtration under reduced pressure, and acetylated CNF was obtained by repeating washing with pure water.

[Evaluation method]
As an evaluation method, the reaction efficiency is evaluated by the degree of substitution of hydroxyl groups in cellulose, the degree of fibrillation is evaluated by the specific surface area, and the shape is observed using a scanning probe microscope (SPM) and a field emission scanning electron microscope (FE-SEM). evaluated with

[Measurement of degree of substitution (evaluation of reaction efficiency)]
Acetone was added to the washed samples obtained in Examples 1 to 5 and Comparative Example 1, and filtered to remove acetone. After that, it was dried at 40° C. using a constant temperature dryer. The degree of substitution (DS) of the dried sample obtained was determined by measuring the infrared (IR) absorption spectrum. In Examples 1 and 2, samples sampled at 14 passes are used.
DS was calculated by the following formula.
DS = 0.0113X - 0.0122 (X is the absorption peak area of ester carbonyl near 1733 cm ^-1 . The spectrum is normalized by 1 at 1315 cm ^-1 )

[Specific surface area measurement (defibration degree evaluation)]
After adding t-butanol to the washed samples obtained in Examples 1 to 5 and stirring well, centrifugation was performed at 4800 G for 5 min using a high-speed cooling centrifuge (Suprema 21, Tommy Industry), and the sample was sedimented. After removing the supernatant, the same amount of t-butanol as the amount of the removed supernatant was added, and after stirring well, centrifugation was performed again under the same conditions. By repeating this operation twice, DMF in the sample was replaced with t-butanol. After that, it was dispersed again in t-butanol and left in a freezer for a whole day and night to freeze. Frozen samples were dried using a vacuum freeze dryer (ALPHA2-4, CHRIST). The resulting freeze-dried sample was subjected to measurement of the specific surface area by the BET method using an automatic specific surface area/pore size distribution measuring device (Tristar II 3020, Shimadzu Corporation) to evaluate the defibration degree of the CNF sample. .

[SPM observation (defibration degree evaluation)]
The washed samples obtained in Examples 3 to 5 were added to DMF at a very low concentration and dispersed uniformly by ultrasonic treatment. After that, a small amount of the solution was dropped on mica and dried to prepare an observation sample. The shape of this sample was observed using an SPM (SPM-9700, Shimadzu Corporation) to evaluate the defibration degree.

[FE-SEM observation (defibration degree evaluation)]
The washed 1, 6, 10, 14, and 22-pass samples obtained in Examples 1 and 2 and the 26-pass sample obtained in Example 1 were measured in the same manner as described for specific surface area measurement. Lyophilized. About 3 nm of platinum was vapor-deposited on the freeze-dried sample to prepare a sample for observation. The shape of this sample was observed using FE-SEM (JSM-6700F, JEOL Ltd.) to evaluate the defibration degree.

[Results and discussion]
The above results are shown in Table 1 and FIGS. 3 to 6E. "-" in Table 1 indicates that the specific surface area was not measured.
FIG. 3 is a graph showing the relationship between the number of treatments, degree of substitution (DS), and temperature change in Examples 1 and 2. FIG. 4A to 4E are FE-SEM observation images and SPM observation images of the samples obtained in Examples 1 to 5, respectively. 5A to 5F are FE-SEM observation images of samples of 1, 6, 10, 14, 22 and 26 passes obtained in Example 1, respectively. 6A to 6E are FE-SEM observation images of 1, 6, 10, 14 and 22 pass samples obtained in Example 2, respectively. Numerical values in parentheses in FIGS. 5A to 6E are specific surface areas. 4A is an enlarged view of FIG. 5D, and FIG. 4B is an enlarged view of FIG. 6D.
The degree of substitution of the raw cellulose is 0.00, and the specific surface area of the raw cellulose is 2.13 m ² /g.

As shown in Table 1, the degree of substitution and the specific surface area were improved under all conditions of Examples 1 to 4, indicating that acetylation and CNF formation proceeded simultaneously. In addition, when looking at the FE-SEM images of each pass in Examples 1 and 2, it can be observed that CNF formation progresses as the number of passes increases. As for Example 5, since there is no catalyst, CNF formation proceeds considerably, but acetylation proceeds only slightly.

Comparing Examples 1 and 2 with Examples 3 and 4, Examples 1 and 2 have a higher degree of substitution and a higher specific surface area. From this, it can be seen that the use of DMAP as a catalyst makes the progress of acetylation faster than that of TEA. Further, as the acetylation progresses, the fibrillation efficiency in DMF tends to improve and the specific surface area tends to increase.

Comparing Example 1 and Example 2, acetylation progresses in Example 2, which has a longer reaction high-pressure pipe. Further, when comparing Example 3 and Example 4 in which the reaction time and reaction temperature were the same, it can be seen that there is no large difference in the degree of substitution and specific surface area. In other words, it can be seen that when a catalyst such as TEA having a low reaction promotion effect is used, the reaction promotion effect is low even if the reaction high-pressure pipe is lengthened.

Comparing Examples 3 and 4 with Comparative Example 1 (same catalyst, same time, almost same temperature), the degree of substitution is improved in Examples 3 and 4; It is considered to have a stimulating effect. In addition, in Comparative Example 1, simultaneous treatment of acetylation and CNF formation (fibrillation) cannot be performed.

[Conclusion]
It can be seen that simultaneous progress of chemical modification and CNF formation is possible by using the production apparatus, dispersion production method, and nanofiber production method of the present invention.

REFERENCE SIGNS LIST 10 raw material tank 20 feed pump 30 hydraulic pressure generation and control unit 40 pressure booster 50 check valve 60 collision chamber 61 orifice nozzle 70 heat exchanger 80 low pressure piping 81 low pressure piping for reaction 90 high pressure piping 91 high pressure piping for reaction 100 manufacturing equipment A reaction Range of low-pressure piping for B Range of high-pressure piping for reaction

Claims (9)

a raw material tank; a low-pressure pipe for circulating a dispersing fluid containing biomass and a reagent for chemically modifying the biomass and being put into the raw material tank; and passing the dispersion fluid put into the raw material tank to the low-pressure pipe a feed pump for supplying, a pressure intensifier for pressurizing the dispersion fluid supplied to the low-pressure pipe, a high-pressure pipe for circulating the dispersion fluid pressurized by the pressure intensifier, and the a collision chamber in which the dispersion fluid is caused to collide with the collision hard body or collide with each other by high-pressure injection treatment; and a heat exchanger that cools the dispersion fluid collided in the collision chamber;
the low pressure piping comprises reaction low pressure piping between the collision chamber and the heat exchanger;
An apparatus for producing a chemically-modified biomass nanofiber dispersion, wherein the high-pressure piping includes a reaction high-pressure piping between the pressure booster and the collision chamber. 2. The apparatus for producing a chemically modified biomass nanofiber dispersion according to claim 1, wherein the reaction low-pressure pipe and the reaction high-pressure pipe have a spiral shape. 3. The apparatus for producing a chemically modified biomass nanofiber dispersion according to claim 1, wherein lengths of the reaction low-pressure pipe and the reaction high-pressure pipe are 50 to 20000 mm. The apparatus for producing a chemically modified biomass nanofiber dispersion liquid according to any one of claims 1 to 3, wherein the reaction low-pressure pipe and the reaction high-pressure pipe are detachable. A dispersion fluid containing biomass and a reagent for chemically modifying the biomass is caused to collide with a collision hard body or with each other by high-pressure jetting, thereby performing a biomass chemical modification step and a fibrillation step. A method for producing a chemically modified biomass nanofiber dispersion, characterized in that it is carried out simultaneously in one step. 6. The method for producing a chemically modified biomass nanofiber dispersion liquid according to claim 5, wherein the high-pressure injection treatment is performed at a pressure of 100 to 245 MPa. Using the chemically modified biomass nanofiber dispersion manufacturing apparatus according to any one of claims 1 to 4, the temperature of the dispersion fluid in the raw material tank is controlled at 10 to 80 ° C., and the high pressure pipe The temperature of the dispersion fluid in the reaction low-pressure pipe is controlled at 10 to 150°C, and the temperature of the dispersion fluid in the reaction low-pressure pipe is controlled at 60 to 200°C. A method for producing a chemically modified biomass nanofiber dispersion. The method for producing a chemically modified biomass nanofiber dispersion according to any one of claims 5 to 7, wherein the high pressure injection treatment is repeated. The unreacted reagent in the chemically modified biomass nanofiber dispersion produced by the chemically modified biomass nanofiber dispersion production method according to any one of claims 5 to 8 is removed, and chemically modified biomass A method for producing chemically modified biomass nanofibers, which comprises recovering nanofibers.

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