JP5108587B2 - Method for producing cellulose dispersion - Google Patents

Description

  The present invention relates to a method for producing a highly transparent fine oxidized cellulose fiber dispersion containing fine oxidized cellulose fibers having an average fiber diameter of 200 nm or less.

  In industrial products, structural materials, cosmetics, foods, gas barrier materials, etc., production of biodegradable and fine cellulose dispersions has been studied.

  Patent Document 1 describes a method for preparing a cellulose dispersion, but does not describe the carboxyl group content of cellulose. In addition, since a super high pressure homogenizer and a medium mill are used in combination, it cannot be said to be a simple manufacturing method.

  Patent Document 2 does not describe the carboxyl group content of cellulose. Since the grinder and the high-pressure homogenizer are substantially used in combination, it is considered that the damage of the cellulose fiber is increased.

  Patent Document 3 does not describe the carboxyl group content of cellulose. Processing is performed with a high-pressure homogenizer, and the fiber width after the processing is 1 μm or more.

  Patent Document 4 describes that a carboxyl group is introduced into cellulose by using periodic acid or a salt thereof, but since a substantial grinder and a high-pressure homogenizer are used, the cellulose fiber is greatly damaged. The number average fiber length after the treatment is considerably large as 0.05 to 0.3 mm.

  Non-Patent Document 1 discloses that the surface of cellulose is oxidized using an oxidizing agent in the presence of bromide and 2,2,6,6-tetramethylhydroxy-1-hydroxy radical in water, and then transparent using Waring Blender. However, there is no description regarding the operating conditions, and the transmittance of light (λ: 550 nm) of the 0.1% dispersion is only 77%.

Non-Patent Document 2 describes that the light transmittance of a 0.1% dispersion is 90% or more, but it is very inefficient because it is stirred for 10 days with a magnetic stirrer.
Japanese Patent No. 3262917 JP 2004-411119 A Japanese Patent Laying-Open No. 2005-270891 JP 2002-194691 A Bio MACROMOLECULES Volume 7, Number 6, June 2006, Published by the American Chemical Society Bio MACROMOLECULES Volume 8, Number 8, August 2007, Published by the American Chemical Society

  This invention makes it a subject to provide the manufacturing method of the fine oxycellulose fiber dispersion liquid which can obtain the highly transparent dispersion liquid containing the oxycellulose fiber refined | miniaturized.

  The present invention provides the following inventions as means for solving the problems.

Invention of Claim 1 oxidizes a cellulose fiber, The process of obtaining the oxidized cellulose fiber whose carboxyl group content of the cellulose which comprises a cellulose fiber is 0.1-2.0 mmol / g,
A process for producing an oxidized cellulose fiber dispersion comprising a step of obtaining an oxidized cellulose fiber having an average fiber diameter of 200 nm or less by mechanically treating the oxidized cellulose fiber,
In the method for producing an oxidized cellulose fiber dispersion, the mechanical treatment is treatment by a high-pressure disperser.

Invention of Claim 3 oxidizes a cellulose fiber, The process of obtaining the oxidized cellulose fiber whose carboxyl group content of the cellulose which comprises a cellulose fiber is 0.1-2.0 mmol / g,
A process for producing an oxidized cellulose fiber dispersion comprising a step of obtaining an oxidized cellulose fiber having an average fiber diameter of 200 nm or less by mechanically treating the oxidized cellulose fiber,
The mechanical treatment is a method for producing an oxidized cellulose fiber dispersion in which the first stage treatment by a high-speed rotary disperser having a rotating body is followed by the second stage treatment by a high-pressure disperser. .

  According to the production method of the present invention, it is possible to obtain a highly transparent aqueous dispersion containing fine oxidized cellulose fibers, and it is also possible to control the transparency to a desired level.

  Hereinafter, the manufacturing method of this invention of a fine oxidization cellulose fiber dispersion is demonstrated for every process.

<Oxidation process>
First, as a pretreatment step before the oxidation treatment, about 10 to 1000 times the amount (mass basis) of water is added to the raw natural cellulose fiber (absolute dry basis), and treated with a mixer or the like. Make a slurry.

  As natural cellulose fibers used as raw materials, wood pulp, non-wood pulp, cotton, silk, wool, chitin, chitosan, alginic acid, collagen, regenerated cellulose, bacterial cellulose and the like can be used.

  Next, the cellulose fiber in the slurry is oxidized to obtain an oxidized cellulose fiber having a carboxyl group content of 0.1 to 2.0 mmol / g of cellulose constituting the cellulose fiber.

  As a method for oxidizing cellulose fibers, for example, 2,2,6,6, -tetramethyl-1-piperidine-N-oxyl (TEMPO) is used as a catalyst, and an oxidizing agent such as sodium hypochlorite, A method of oxidizing in combination with bromide such as sodium bromide can be applied.

  The amount of TEMPO used is 0.1 to 10% by mass, preferably 0.2 to 8% by mass, more preferably 0.4 to 5% by mass, based on the cellulose fiber (absolute dry basis) used as a raw material. It is. If it is 0.1% by mass or more, the oxidation reaction proceeds smoothly, and if it is 10% by mass or less, the removal burden in the subsequent process is reduced.

  As the oxidizing agent, hypohalous acid or a salt thereof, or halogenous acid or a salt thereof can be used. Examples of hypohalites include sodium hypochlorite, potassium hypochlorite, and lithium hypochlorite. Examples of the halite include sodium chlorite, potassium chlorite, and lithium chlorite. The oxidizing agent is preferably sodium hypochlorite. When sodium hypochlorite is used, increasing the proportion of cellulose fiber used increases the amount of carboxyl groups introduced, increasing the electrostatic repulsion between the fibers or acting directly on the fibers. By doing so, the dispersibility of the fibers is improved and the transparency is promoted.

  The amount of the oxidizing agent used is 0.1 mmol to 10 mmol, preferably 1 mmol to 10 mmol, more preferably 1.5 mmol to 10 mmol, still more preferably 2.0 mmol with respect to 1 g of cellulose fiber (absolute dry basis) used as a raw material. 10 mmol, more preferably 2.3 mmol to 10 mmol, further preferably 2.5 mmol to 10 mmol, more preferably 3.0 mmol to 9 mmol, particularly preferably 4.0 mmol to 9 mmol. When the amount is 0.1 mmol or more, the oxidation reaction proceeds smoothly, and a transparent dispersion can be obtained. Further, the dispersion is easily reduced in viscosity, and when the amount is 10 mmol or less, the removal burden in the subsequent process is reduced. .

  Examples of the bromide include lithium bromide, potassium bromide, sodium bromide and the like, and sodium bromide is preferable.

  The amount of bromide used is 0.1 mmol to 10 mmol, preferably 0.5 mmol to 7 mmol, and more preferably 0.7 mmol to 5 mmol, with respect to 1 g of cellulose fiber (absolute dry basis) used as a raw material. If it is 0.1 mmol or more, the oxidation reaction proceeds smoothly, and if it is 5 mmol or less, the removal burden in the subsequent process is reduced.

  The pH is preferably in the range of 9.0 to 12.0 from the viewpoint of allowing the oxidation reaction to proceed efficiently. More preferably, the pH is 9.5 to 11.5.

  The temperature (temperature of the slurry) and time for the oxidation treatment are 1 to 50 ° C., and preferably 1 to 300 minutes.

  After the treatment in this step is completed, the used catalyst and the like may be removed by washing with water and the like, and drying treatment may be performed as necessary.

  By the treatment in this step, the C6 position of the cellulose constituent unit can be selectively oxidized to a carboxyl group, and the carboxyl group content of the cellulose constituting the cellulose fiber can be 0.1 to 2.0 mmol / g. it can. The content is preferably 0.4 to 2.0 mmol / g, more preferably 0.5 to 1.7 mmol / g, and still more preferably 0.6 to 1.7 mmol / g. Said carboxyl group content is calculated | required by the measuring method as described in an Example. In addition, when the lower limit of the carboxyl group content is 0.1 mmol / g or more, the average fiber diameter of the cellulose fibers becomes 200 nm or less by the fiber refining treatment described later, and the transparent content with a solid content concentration of 0.1 mass% is obtained. An aqueous dispersion is obtained. Furthermore, when the carboxyl group content is within the above range, the transparency of the aqueous dispersion having a solid content concentration of 0.1% by mass refinement (evaluated by the visual observation or the transmittance described in the examples) is improved. It becomes easy to make.

<Mechanical treatment process>
Next, the oxidized cellulose fiber obtained in the previous step is refined to a mean fiber diameter of 200 nm or less by mechanical treatment. As the mechanical treatment in this step, the following methods (I) and (II) can be applied. The oxidized cellulose fiber is preferably mechanically treated after it is made into an aqueous dispersion having a solid concentration of 0.01 to 10% by mass, preferably 0.05 to 5% by mass.

Method (I) This is a method of processing using a high-pressure disperser as the mechanical processing. High-pressure dispersers include high-pressure homogenizer (Invensys System Co., Ltd.), Nanomizer (Yoshida Kikai Kogyo Co., Ltd.), Microfluidizer (MFIC Corp.), Ultimateizer System (Sugino Machine Co., Ltd.), Soundless A high-pressure emulsifying and dispersing device (Bigrain Co., Ltd.) can be used. These devices, when the treated object (aqueous dispersion of oxidized cellulose fiber) is passed through a fine flow path at high pressure, the fluid and the wall surface generated by the high shear force generated in the flow path and the device of the flow path. , The impact force caused by the collision between fluids, cavitation generated when discharged from a fine flow path, and the like.

  The operating pressure is preferably 10 to 400 MPa, more preferably 20 to 350 MPa, and even more preferably 30 to 300 MPa. The high-pressure disperser treatment can be repeated 1 to 100 times. The treatment here (one or more treatments) means that what has been treated once with the high-pressure disperser is treated again, and in the present invention, one treatment means one pass and one treatment. The second processing is referred to as two passes, and the same three processing is referred to as three passes. The number of passes is preferably 1 to 20 passes and more preferably 1 to 10 passes from the viewpoint of productivity. As a processing method, there is also a method of performing a circulation process by returning the dispersion liquid discharged from the high-pressure disperser fed from the raw material tank directly to the raw material tank.

  In the method (I), as a feature of the present oxidized cellulose, a highly transparent aqueous dispersion can be obtained even at a relatively low pressure. For example, even an operating pressure of 60 MPa or less can be processed in 10 passes or less, preferably 5 passes or less.

Method (II) In this method, the mechanical treatment is a first stage treatment by a high-speed rotary disperser having a rotating body, followed by a second stage treatment by a high-pressure disperser.

  If coarse fibers in the oxidized cellulose fiber are dispersed in the first stage treatment, the second stage high-pressure disperser treatment can be performed more efficiently.

  The first stage processing by the high-speed rotary disperser having a rotating body uses a high-speed rotating disperser having one or two or more rotating bodies serving as stirring means as a mechanical process, and the blade tip of the rotating body is used. The peripheral speed (hereinafter referred to as “peripheral speed”) is 10 m / s or more. The peripheral speed is 10 m / s or more, preferably 15 m / s or more, more preferably 20 m / s or more, and particularly preferably 22 m / s or more. The upper limit of the peripheral speed is not particularly present, but is preferably 100 m / s or less in view of economy and the mechanical strength of the disperser.

  The processing time can be appropriately set in relation to the peripheral speed, the capacity of the processing tank, the amount of processing performed once, and the like. For example, when the peripheral speed of the rotating body is 20 m / s, the capacity of the treatment tank is 1 L, and 500 g of an aqueous dispersion having a solid content concentration of 1% by mass is used, the treatment time is about 1 to 120 minutes.

  The high-speed rotating disperser is miniaturized by shearing force, impact force, and cavitation generated in the vicinity of a rotating body that rotates at high speed. The rotating body is a known one such as a stirring blade of various shapes, or one in which the tank itself rotates.

  The high-speed rotary disperser is a type in which the oxidized cellulose fiber to be processed is passed through the gap between the rotating body and the fixed part to disperse the inner rotating body rotating in a certain direction and the outside of the inner rotating body reversed. And an outer rotator rotating around the outer rotator, and the oxycellulose fiber to be treated is passed through and dispersed in the gap between the inner rotator and the outer rotator. High-speed rotary dispersers include, for example, M Technique's Claremix, Taihei Koki Co., Ltd. Milder, Primics Co., Ltd. TK Robotics, and Taihei Kiko Co., Ltd. Machine (Cabitron), high-speed rotary disperser (Sharp Flow Mill) from Taiheiyo Kiko Co., Ltd., thin-film swivel type high-speed rotary disperser (Filmix, etc.) manufactured by Primix Co., Ltd. A medium stirring type disperser (SC mill) manufactured by Mitsui Mining Co., Ltd. can be used as one that can obtain the same effect as the type disperser.

Since a high shear rate (unit s ⁻¹ ) can be generated by passing through a narrow gap while rotating at a high speed in this way, compared with a case where it is simply rotated at a high speed (that is, like a domestic juicer mixer). In addition, compared with the case where mechanical means having a large gap and a low shear rate are used, the refinement process can be effectively performed. The size of the gap is preferably 5 mm or less, more preferably 3 mm or less, and still more preferably 2 mm or less.

  The second stage treatment by the high-pressure disperser can be performed in the same manner as in the method (I), and the operation pressure is preferably 10 to 400 MPa. Further, the operation pressure can be 100 MPa or more, for example, 100 to 300 MPa, and only one treatment may be performed, but a treatment of 2 to 5 passes is preferable.

  The fine oxidized cellulose fiber obtained by the production method of the present invention has an average fiber diameter of 200 nm or less, preferably 1 to 200 nm, more preferably 1 to 100 nm, from the viewpoint of increasing the transparency of the aqueous dispersion. Preferably it is 1-50 nm. An average fiber diameter is calculated | required by the measuring method as described in an Example.

  The fine oxidized cellulose fiber obtained by the production method of the present invention preferably has an average fiber length of 40 μm or less from the viewpoint of increasing the transparency of the aqueous dispersion.

  The fine oxidized cellulose fiber obtained by the production method of the present invention preferably has an average aspect ratio (average fiber length / average fiber diameter) of 10 to 5,000, more preferably 10 to 2,000, still more preferably 10. ~ 1,000, more preferably 10-500.

  The aqueous dispersion obtained by the production method of the present invention has high transparency, and the transmittance measured by the method described in Examples can be 80% or more, preferably 85% or more, more preferably 90% or more. Can be.

  The transparency can be controlled to a desired level by appropriately selecting conditions in the oxidation treatment and the mechanical treatment. For example, in the oxidation treatment, the oxidation conditions are selected so that the carboxyl group content of the cellulose constituting the cellulose fiber is in a more preferable range. In the method (II), the transmittance can be maximized by optimally setting the peripheral speed, processing time, processing amount, the operation pressure, and the number of passes (for example, Examples 4 and 6). , 7, the transmittance is 99%). Then, by relaxing the oxidation treatment and the mechanical treatment conditions, the transmittance can be reduced from the maximum value to a desired level.

  The aqueous dispersion containing the refined oxidized cellulose fiber obtained by the production method of the present invention is used, if necessary, by removing the used catalyst by washing or the like, and in the form of a suspension (visually colorless and transparent or opaque Liquid) or, if necessary, dried powder (however, it is fibrous and does not mean grains). In addition, when making into suspension, what used only water may be used, and the mixed solvent of water, other organic solvents (for example, alcohol, such as ethanol), surfactant, an acid, a base, etc. was used. It may be a thing.

  The aqueous dispersion containing refined oxidized cellulose fibers obtained by the production method of the present invention can be used, for example, as a material for producing an oxygen barrier film or a water vapor barrier film.

  The measuring method of each item shown in Table 1 is as follows.

(1) Average fiber diameter As a pretreatment, the sample dispersion was diluted to 0.01 to 0.005% cellulose with ion-exchanged water. Next, after dropping one drop on the wall surface of the mica, water drops were blown off with air or the like and allowed to dry naturally. The measurement was performed on an image of cellulose fibers taken with an atomic force microscope (Veeco Dimension 3000 Tapping mode). Ten or more fiber diameters were extracted, measured from the height profile of the cross section of each fiber, and the average value was taken.

(2) Carboxyl group content (mmol / g)
About 0.5 g of absolutely dry pulp is put into a 100 ml beaker, and ion-exchanged water is added to make a total of 55 ml, and 5 ml of 0.01 M sodium chloride aqueous solution is added thereto to obtain a 0.83% by mass pulp suspension. Stir with a stirrer until dispersed. Then, 0.1M hydrochloric acid is added to adjust the pH to 2.5 to 3.0, and then using an automatic titrator (AUT-501, manufactured by Toa DKK Co., Ltd.), a 0.05M sodium hydroxide aqueous solution is waited for 60 seconds. The electric conductivity and pH value of the pulp suspension every minute were measured, and the measurement was continued until the pH reached about 11. And the sodium hydroxide titration amount was calculated | required from the obtained electrical conductivity curve, and carboxyl group content was computed.

(3) Transmittance (%)
The obtained aqueous dispersion of cellulose is diluted with pure water to obtain a 0.1% by mass aqueous dispersion. The obtained dispersion was put into a measurement cell, and the transmittance at a light wavelength of 550 nm was measured with a spectrophotometer (UVmini 1240, manufactured by Shimadzu Corporation).

Example 1
As a cellulose fiber raw material, bleached kraft pulp of coniferous tree (manufacturer: Fletcher Challenge Canada, trade name “Machenzie”, CSF 650 ml) was used.

<Pretreatment process>
First, 3 g of the bleached kraft pulp fiber of the above-mentioned conifer was sufficiently stirred with 297 g of ion-exchanged water and defibrated to some extent.

<Oxidation process>
Thereafter, the amount of TEMPO (manufacturer: ALDRICH, Free radical 98% by mass) becomes 1.25% by mass, sodium hypochlorite (Wako Pure Chemical Industries, Ltd., Cl concentration 5% by mass with respect to 3 g of pulp mass. ) 2.5 mmol / g-half sodium bromide (Wako Pure Chemical Industries, Ltd.) 3.6 mmol / g-half pH was added in this order. Then, it was dropped with 0.5M sodium hydroxide using a pH stud, the pH was maintained at 10.5 and the temperature was 25 ° C., and an oxidation reaction was performed for 60 minutes to obtain oxidized pulp. The oxidized pulp was sufficiently washed with ion-exchanged water and dehydrated.

  Next, an aqueous dispersion in which the solid content concentration of the obtained oxidized pulp was adjusted to 0.25% by mass was obtained. Next, a two-pass treatment was performed at a pressure of 50 MPa with a high-pressure disperser (Nanomizer, model number: YSNM-1500AR, manufactured by Yoshida Kikai Kogyo Co., Ltd.) while stirring the aqueous dispersion. The transmittance of the aqueous dispersion after the treatment was 96%. The average fiber diameter was 3.6 nm.

Example 2
An oxidized pulp was obtained in the same manner as in Example 1 except that the sodium hypochlorite concentration was changed to the concentration shown in Table 1.

  Next, 600 g of an aqueous dispersion in which the solid content concentration of the obtained oxidized pulp was adjusted to 0.5% by mass was used, and a high-speed rotary disperser (TK Robotics, manufactured by Primix Co., Ltd., rotation speed 10,000 rpm, blade The treatment was carried out for 10 minutes at a peripheral speed of 13 m / s and a gap between the rotating body and the fixed part of 0.5 mm).

  Thereafter, a two-pass treatment was performed at a high pressure disperser (Nanomizer, model number: YSNM-1500AR, manufactured by Yoshida Kikai Kogyo Co., Ltd.) at a pressure of 50 MPa. The transmittance of the aqueous dispersion after the treatment was 84%. The average fiber diameter was 3.5 nm.

Example 3
Processing was carried out in the same manner as in Example 2. However, the high-pressure disperser performed a 3-pass process. The transmittance of the aqueous dispersion after the treatment was 96%. The average fiber diameter was 3.1 nm.

Example 4
An oxidized pulp was obtained in the same manner as in Example 1 except that the sodium hypochlorite concentration was changed to the concentration shown in Table 1. Next, an aqueous dispersion in which the solid content concentration of the obtained oxidized pulp was adjusted to 0.25% by mass was obtained.

  600 g of the obtained aqueous dispersion was treated for 10 minutes with a high-speed rotating disperser (TK Robotics, manufactured by Primics Co., Ltd., homomixer, rotation speed 10000 rpm, blade peripheral speed 13 m / s).

  Thereafter, a two-pass treatment was performed at a high pressure disperser (microfluidizer, model number: MF-110E / H, manufactured by MFIC Corp.) at a pressure of 150 MPa. The transmittance of the aqueous dispersion after the treatment was 99%. The average fiber diameter was 4.4 nm.

Example 5
An oxidized pulp was obtained in the same manner as in Example 1 except that the sodium hypochlorite concentration was changed to the concentration shown in Table 1. Next, an aqueous dispersion in which the solid content concentration of the obtained oxidized pulp was adjusted to 1.0% by mass was obtained.

  2500 g of the obtained aqueous dispersion was treated for 60 minutes with a high-speed rotary disperser (Milder, manufactured by Taihei Koki Co., Ltd., rotation speed 15000 rpm, rotary blade peripheral speed 24 m / s).

  Thereafter, a one-pass treatment was performed at a pressure of 245 MPa using a high-pressure disperser (Ultimizer system: manufactured by Sugino Machine Co., Ltd.). The transmittance of the aqueous dispersion after treatment was 98%. The average fiber diameter was 3.5 nm. The viscosity of the obtained dispersion was 5600 mPa · s at 25 ° C. (viscosity measurement: B-type viscometer, rotor No. 4, rotation speed 60 rpm). The viscosity of the dispersion obtained by the 3-pass treatment with the high-pressure disperser was 2990 mPa · s at 25 ° C. (viscosity measurement: B-type viscometer, rotor No. 4, rotation speed 60 rpm).

Example 6
An oxidized pulp was obtained in the same manner as in Example 1 except that the sodium hypochlorite concentration was changed to the concentration shown in Table 1. Next, an aqueous dispersion in which the solid content concentration of the obtained oxidized pulp was adjusted to 2.0% by mass was obtained.

  2500 g of the obtained aqueous dispersion was used as a high-speed rotary disperser (milder, model number: MDN303V, manufactured by Taihei Koki Co., Ltd., rotation speed 15000 rpm, rotating blade peripheral speed 24 m / s, gap between the rotating body and the fixed part At 0.5 mm) for 60 minutes.

  Thereafter, a 3-pass treatment was performed at a pressure of 245 MPa with a high-pressure disperser (Ultimizer system, model number: Starburst Mini HJP-25001, manufactured by Sugino Machine Co., Ltd.). The transmittance of the aqueous dispersion after the treatment was 99%. The average fiber diameter was 3.1 nm.

Example 7
An oxidized pulp was obtained in the same manner as in Example 1 except that the sodium hypochlorite concentration was changed to the concentration shown in Table 1. Next, an aqueous dispersion in which the solid content concentration of the obtained oxidized pulp was adjusted to 1.0% by mass was obtained.

  2500 g of the obtained aqueous dispersion was treated for 60 minutes with a high-speed rotary disperser (Milder, manufactured by Taihei Koki Co., Ltd., rotation speed 15000 rpm, rotary blade peripheral speed 24 m / s).

  Thereafter, a one-pass treatment was performed at a pressure of 245 MPa using a high-pressure disperser (Ultimizer system: manufactured by Sugino Machine Co., Ltd.). The transmittance of the aqueous dispersion after the treatment was 99%. The average fiber diameter was 3.3 nm. The viscosity of the obtained dispersion was 2200 mPa · s at 25 ° C. (viscosity measurement: B-type viscometer, rotor No. 2, rotation speed 60 rpm).

Comparative Example 1
Using 600 g of an aqueous dispersion in which the solid content concentration of the oxidized pulp obtained in Example 1 was adjusted to 0.5% by mass, a high-speed rotary disperser (TK Robotics, manufactured by Primix Co., Ltd., rotation speed 10000 rpm, The blade was processed at a blade peripheral speed of 13 m / s for 30 minutes. The transmittance of the aqueous dispersion after treatment was 68%. The average fiber diameter was 3.6 nm.

Comparative Example 2
In Comparative Example 1, the production was performed in the same manner except that the treatment was performed for 120 minutes. The transmittance of the aqueous dispersion after treatment was 76%. The average fiber diameter was 3.4 nm.

Comparative Example 3
It was produced in the same manner as in Example 1 except that a pulp slurry having a concentration of 0.25% by mass that did not undergo oxidation reaction in Example 1 was prepared. The transmittance of the aqueous dispersion after treatment was 31%. Since the average fiber diameter was very large, it was observed by optical microscope observation. The average fiber diameter was 20 μm.

Comparative Example 4
In Example 1, a pulp slurry having a concentration of 0.25% by mass that does not undergo an oxidation reaction was prepared, and then a pressure of 50 MPa using a high-pressure disperser (Nanomizer, model number: YNMM-1500AR, manufactured by Yoshida Machine Industries, Ltd.). I tried to process it, but it was clogged and could not be processed.

Claims (3)

Oxidizing the cellulose fiber to obtain an oxidized cellulose fiber having a carboxyl group content of 0.1 to 2.0 mmol / g of cellulose constituting the cellulose fiber;
A process for producing an oxidized cellulose fiber dispersion comprising a step of obtaining an oxidized cellulose fiber having an average fiber diameter of 200 nm or less by mechanically treating the oxidized cellulose fiber,
A method for producing an oxidized cellulose fiber dispersion, wherein the mechanical treatment is treatment by a high-pressure disperser at an operating pressure of 10 MPa to 400 MPa . Oxidizing the cellulose fiber to obtain an oxidized cellulose fiber having a carboxyl group content of 0.1 to 2.0 mmol / g of cellulose constituting the cellulose fiber;
A process for producing an oxidized cellulose fiber dispersion comprising a step of obtaining an oxidized cellulose fiber having an average fiber diameter of 200 nm or less by mechanically treating the oxidized cellulose fiber,
The method for producing an oxidized cellulose fiber dispersion, wherein the mechanical treatment is a first-stage treatment using a high-speed rotary disperser having a rotating body followed by a second-stage treatment using a high-pressure disperser. The first stage process by the high-speed rotary disperser having the rotating body is a process in which the peripheral speed of the blade tip of the rotating body is 10 m / s or more, and the second stage process by the high-pressure disperser is: The manufacturing method of Claim 2 which is the process by the operating pressure of 10 MPa-400 MPa.