KR101856497B1 - Microfibrillated cellulose and preparation method thereof - Google Patents

Abstract

The present invention relates to a microfibrillated cellulose which is surface-modified with ammonium ions having weight average molecular weight of 300 to 10,000, and a production method thereof. Since the microfibrillated cellulose has hydrophilicity and hydrophobicity, microfibrillated cellulose can be easily dispersed, while re-agglomeration due to hydrogen bonding is minimized.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a microfibrous cellulose and a method for producing the microfibrous cellulose.

The present invention relates to a microfibrous cellulose which has both hydrophilicity and hydrophobicity and is easily dispersed and surface-modified with ammonium ion, which minimizes re-aggregation due to hydrogen bonding, and a method for producing the microfibrous cellulose.

Cellulose is one of the most common natural polymers found on the earth, found in most plants such as wood, cotton, and shrub, as well as in animals with dry epidermis such as muddock and urchins, 1-4 glucosidic linkages and has a molecular weight of 4.6 × 10 ⁵ to 1.7 × 10 ⁶ . Cellulose is a structural unit that forms the skeleton of plants. It is a major component of the cell membrane of all higher plant cells, and plants, especially wood, play a key role in maintaining high strength.

Cellulosic molecules having an effective diameter of about 6 to 7 angstroms are regularly bonded through hydrogen bonding and are strongly bonded to form microfibrillated or nanofibrillated cellulose having a diameter of 2 to 5 nm. And these fibers constitute the cell membranes of the plants.

Recently, microfibrous cellulose has been utilized as a new functional material in various applications due to its chemical, physical and optical merits. In the past, it has been commercialized as an additive for bio-polymer composite materials for automobile bodywork, as a barrier film for foods and electronic devices, as an additive for cosmetics, and as an additive for cement. In recent years, , Flexible display substrates, flexible solar cell materials, encapsulants for electronic devices, optical instruments, and drug delivery.

Methods for producing such microfibrous cellulose include acid-hydrolysis, electrospinning, bacterial culture, and mechanical-physical methods. Particularly, the method of manufacturing by mechanical-physical method is evaluated as the most promising technique in terms of physical properties and mass production have.

However, the mechanical or physical method has a problem of re-agglomeration even after being separated from cellulose into microfibrous cellulose by hydrogen bonding due to a hydroxyl group remaining on the surface of microfibrous cellulose.

Particularly, such coagulation phenomenon acts as a major factor for inhibiting the dispersion of microfibrous cellulose in the process of compounding with heterogeneous materials. Therefore, in order to prevent re-agglomeration of microfibrous cellulose and to disperse easily, Is required. In this process, additional energy costs such as pulverization force, shear force, and cavitation corresponding to the energy required in the microfibrous cellulose manufacturing process are incurred, Dispersion treatment has a problem that crystallization and aspect ratio of microfibrous cellulose are lowered, resulting in deterioration of mechanical and chemical performance of microfibrous cellulose.

It is an object of the present invention to provide a high-quality microfibrous cellulose having both hydrophilicity and hydrophobicity and being easily dispersed and minimizing re-aggregation due to hydrogen bonding, and a method for producing the microfibrous cellulose.

In order to achieve the above object,

There is provided a microfibrillated cellulose represented by the following Chemical Formula 1 and surface-modified with an ammonium ion having a weight average molecular weight of 300 to 10,000:

≪ Formula 1 >

In Formula 1,

R ₁ to R ₄ independently represent hydrogen, deuterium, C ₁ -C ₆₀ alkyl, C ₂ -C ₆₀ alkenyl, C ₂ -C ₆₀ alkynyl, C ₃ -C ₆₀ cycloalkyl, C ₃ -C ₆₀ A cycloalkenyl group or a C ₆ -C ₆₀ aryl group.

Further, in one embodiment,

(a) swelling cellulose by immersing it in a polar solvent;

(b) mixing the swollen cellulose with the ammonium ion represented by Formula 1 and having a weight average molecular weight of 300 to 10,000 in the polar solvent; And

(c) fibrillating the mixture of the swollen cellulose and the ammonium ion using a shearing device to obtain a microfibrous cellulose surface-modified with the ammonium ion; and .

The microfibrous cellulose according to the present invention is easily dispersed in a material having hydrophobic characteristics due to a hydrophobic substituent among ammonium ions bonded to the surface of microfibrous cellulose.

In addition, the microfibrous cellulose may be present as a high-quality microfibrous cellulose since the re-aggregation due to hydrogen bonding is minimized due to the steric hindrance effect imparted by the ammonium ion bonded to the surface of the microfibrous cellulose.

According to the method for producing microfibrous cellulose according to the present invention, since the step of fibrillating cellulose and the step of modifying the surface of cellulose are simultaneously performed, it is possible to prevent aggregation by hydrogen bonding of microfibrous cellulose, It is possible to produce a microfibrous cellulose having a high degree of crystallinity and a high aspect ratio.

1 is a schematic view showing the structure of cellulose.
2 is a schematic view showing a microfibrous cellulose surface-modified with ammonium ions.
3 shows an SEM photograph of the microfibrous cellulose prepared in the example.
Fig. 4 shows an SEM photograph of the microfibrous cellulose prepared in the comparative example.
Fig. 5 shows the solvent dispersion of microfibrous cellulose produced in Examples and Comparative Examples in methanol.
Fig. 6 shows the solvent dispersion of the microfibrous cellulose prepared in Examples and Comparative Examples in ethyl acetate. Fig.
Fig. 7 shows the solvent dispersions of the microfibrous cellulose prepared in Examples and Comparative Examples in toluene. Fig.

Hereinafter, the present invention will be described in detail by way of examples. The embodiments can be modified into various forms as long as the gist of the invention is not changed.

As used herein, " comprising "means that other elements may be included unless otherwise specified.

The present invention provides a microfibrous cellulose represented by the following general formula (1) and surface-modified with ammonium ions having a weight average molecular weight of 300 to 10,000, and a process for producing the microfibrous cellulose:

≪ Formula 1 >

In Formula 1,

R ₁ to R ₄ independently represent hydrogen, deuterium, C ₁ -C ₆₀ alkyl, C ₂ -C ₆₀ alkenyl, C ₂ -C ₆₀ alkynyl, C ₃ -C ₆₀ cycloalkyl, C ₃ -C ₆₀ A cycloalkenyl group or a C ₆ -C ₆₀ aryl group.

[ Fibrous fibrous  cellulose]

The microfibrous cellulose according to one embodiment is characterized in that it is surface-modified with ammonium ions.

The ammonium ion is represented by the following formula (1).

≪ Formula 1 >

In Formula 1,

R ₁ to R ₄ independently represent hydrogen, deuterium, C ₁ -C ₆₀ alkyl, C ₂ -C ₆₀ alkenyl, C ₂ -C ₆₀ alkynyl, C ₃ -C ₆₀ cycloalkyl, C ₃ -C ₆₀ A cycloalkenyl group or a C ₆ -C ₆₀ aryl group.

Wherein R ₁ to R ₄ independently represent a C ₁ -C ₆₀ alkyl group, a C ₂ -C ₆₀ alkenyl group, a C ₂ -C ₆₀ alkynyl group, a C ₃ -C ₆₀ cycloalkyl group, a C ₃ -C ₆₀ cycloalkenyl group Or a C ₆ -C ₆₀ aryl group, each independently of the other, a C ₁ -C ₆₀ alkyl group, a C ₂ -C ₆₀ alkenyl group, a C ₂ -C ₆₀ alkynyl group, a C ₃ -C ₆₀ cycloalkyl group, a C ₃ -C ₆₀ cyclo An alkenyl group or a C ₆ -C ₆₀ aryl group, and when they are substituted with a plurality of substituents, they may be the same or different from each other.

The above-mentioned "alkyl group" means a monovalent substituent derived from a linear or branched saturated hydrocarbon having 1 to 60 carbon atoms. Examples thereof include, but are not limited to, methyl, ethyl, propyl, isobutyl, sec-butyl, tert-butyl, pentyl and hexyl.

The "alkenyl group" as used herein means a monovalent substituent derived from a straight-chain or branched-chain unsaturated hydrocarbon having 2 to 60 carbon atoms and having at least one carbon-carbon double bond. Examples thereof include, but are not limited to, vinyl, allyl, isopropenyl, 2-butenyl, and the like.

The above-mentioned "alkynyl group" means a monovalent substituent derived from a straight-chain or branched-chain unsaturated hydrocarbon having 2 to 60 carbon atoms and having at least one carbon-carbon triple bond. Examples thereof include, but are not limited to, ethynyl, 2-propynyl, and the like.

The "cycloalkyl group" means a monovalent substituent derived from a monocyclic or polycyclic non-aromatic hydrocarbon having 3 to 60 carbon atoms. Examples of such cycloalkyls include, but are not limited to, cyclopropyl, cyclopentyl, cyclohexyl, norbornyl, adamantine, and the like.

The above-mentioned "cycloalkenyl group" means a monovalent substituent derived from a monocyclic or polycyclic non-aromatic hydrocarbon having 3 to 60 carbon atoms and having at least one carbon-carbon double bond.

The "aryl group" means a monovalent substituent derived from a C6-C60 aromatic hydrocarbon having a single ring or a combination of two or more rings. Also, a form in which two or more rings are pendant or condensed with each other may be included. Examples of such aryl include, but are not limited to, phenyl, naphthyl, phenanthryl, anthryl, and the like.

The weight average molecular weight of the ammonium ion is 300 to 10,000. Specifically, the weight average molecular weight of the ammonium ion is 450 to 7,500. More specifically, the weight average molecular weight of the ammonium ion may be 500 to 5,000, but is not limited thereto.

When the weight average molecular weight of the ammonium ion is in the above range, the microfibrous cellulose is easily dispersed in a material having hydrophobic characteristics.

The ammonium ion is at least one selected from the group consisting of a secondary ammonium ion, a tertiary ammonium ion, and a quaternary ammonium ion.

For example, the ammonium ion may be a C ₁₈ -C ₆₀ alkyl group is substituted with two secondary ammonium ion. Or the ammonium ion may be a C ₁₈ -C ₆₀ alkyl group is 1, C ₁₈ -C ₆₀ aryl group substituted with one secondary ammonium ion. As another example, the ammonium ion may be a tertiary ammonium ion having two C ₁₈ -C ₆₀ alkyl groups and one C ₆ -C ₆₀ aryl group substituted. Or the ammonium ion may be a quaternary ammonium ion in which four C ₆ -C ₆₀ alkyl groups are substituted.

When the ammonium ion is at least one selected from the group consisting of a secondary ammonium ion, a tertiary ammonium ion and a quaternary ammonium ion and the ammonium ion is bonded to the surface of the microfibrous cellulose, It is possible to prevent the problem of re-agglomeration even after separation into cellulosic fibrous cellulose by hydrogen bonding due to a hydroxyl group of hydroxyl groups, and it is also possible to easily disperse into a material having hydrophobic characteristics.

The ammonium ion is bound to the -OH group of the microfibril cellulose by an electrostatic attractive force.

There is -OH group (hydroxyl group) in the microfibrous cellulose and strong hydrogen bond exists between -OH group and H. However, hydrogen bonding can be weakened by binding the ammonium ion to the -OH group of the microfibrous cellulose by electrostatic attraction.

Specifically, since the electronegativity of oxygen in the -OH group is large, oxygen is partially negatively charged and N in the ammonium ion is positively charged. Therefore, electrostatic attraction between N of the ammonium ion and O of the -OH group .

It is possible to prevent the problem that the fibrillated microfibrous cellulose is re-agglomerated by binding the ammonium ion to the -OH group of the microfibrous cellulose by electrostatic attraction.

The microfibrillated cellulose is microfibrillated cellulose or nanofibrillated cellulose.

The microfibrous cellulose has a diameter of 5 nm to 100 nm. Specifically, the diameter of the microfibrous cellulose may be 5 nm to 50 nm, more specifically 5 nm to 10 nm, but is not limited thereto.

The length of the microfibrous cellulose is 100 nm to 500 탆. Specifically, the length of the microfibrous cellulose may be 100 nm to 100 탆, more specifically, 100 nm to 10 탆, but is not limited thereto.

The diameter and length of the microfibrous cellulose are obtained by thinly casting a microfibrous cellulose dispersion on a substrate and drying the microfibrous cellulose dispersion, measuring the average length of the plurality of fibers and the diameter measured by AFM (Atomic Force Microscope) do.

When the diameter and the length of the microfibrous cellulose are in the above range, it is possible to produce a microfibrous cellulose of high quality and to prevent re-aggregation. In particular, it is advantageous to disperse it when used as an additive for a polymer composite material.

The content of ammonium ion in the microfibrous cellulose is 0.1 to 5% by weight based on the total weight of the microfibrous cellulose. Specifically, the content of ammonium ions in the microfibrous cellulose is 0.1 to 3% by weight. More specifically, the content of ammonium ions in the microfibrous cellulose may be 0.1 to 1% by weight, but is not limited thereto.

When the content of the ammonium ion in the microfibrous cellulose is in the above range, re-aggregation can be prevented, dispersion in a polymer composite material having hydrophobic properties is facilitated, and it is economical in terms of cost.

The crystallinity of the microfibrous cellulose is 50 to 100%. Specifically, the crystallinity of the microfibrous cellulose may be 70 to 100%, more specifically 80 to 100%, but is not limited thereto.

The crystallinity is the ratio of the weight of the crystalline portion to the total weight of the microfibrous cellulose.

When the crystallinity of the microfibrous cellulose is in the above range, it is advantageous to increase the mechanical strength of the microfibrous cellulose.

The microfibrous cellulose that is surface-modified with the ammonium ion is bonded to the microfibrous cellulose having the hydrophilic property and the ammonium ion having the hydrophobic property so that the surface-modified microfibrous cellulose is not only hydrophilic but also hydrophobic It is easy to disperse even when it is.

Therefore, by having high mechanical properties, low coefficient of thermal expansion, high specific surface area, high aspect ratio, high transparency and high dimensional stability, it is possible to provide a filler, a pressure sensor for a polymer composite, a filter for water or air, , Flexible solar cell materials, sealing materials for electronic devices, optical devices, drug delivery, and the like.

[ Fibrous fibrous  Method for producing cellulose]

In one embodiment, the method of producing the microfibrous cellulose described above comprises:

(a) swelling cellulose by immersing it in a polar solvent;

(b) mixing the swollen cellulose with the ammonium ion represented by the following formula (1) and having a weight average molecular weight of 300 to 10,000 in the polar solvent; And

(c) fibrillating the mixture of the swollen cellulose and the ammonium ion using a shearing device to obtain a microfibrous cellulose surface-modified with the ammonium ion.

≪ Formula 1 >

The description of Formula 1 refers to the description given in [Fibrous Cellulose] above.

First, cellulose was dissolved in a polar solvent Immerse  Swell.

The cellulose is not particularly limited, and one derived from a cellulose-containing material can be used. For example, pulp, chemical pulp, mechanical pulp, recycled pulp, cellulose powder or a mixture thereof can be used. Examples of the cellulose-containing material include cellulosic fibers such as cellulosic fibers and cellulose acetate produced by plants or bacteria that are natural fibers, chitin derivatives such as chitin and chitosan contained in crustaceans such as sea urchins, shrimp and crabs, , And the like, but the present invention is not limited thereto. In addition, the cellulose fiber-containing material containing plant as a raw material may be wood such as coniferous or hardwood, cotton, hemp, or sheep. Cellulosic fibers obtained from wood such as coniferous trees and broad-leaved trees are very finely structured and have high strength and are the most distributed biomass on the planet.

The cellulose used in this case may have a diameter of 10 to 1,000 mu m and a length of 0.1 to 100 mm. Specifically, the cellulose used may have a diameter of 10 to 500 mu m and a length of 0.1 to 50 mm, but is not limited thereto.

The polar solvent is a polar protic solvent or a polar aprotic solvent.

Specifically, the polar solvent is selected from the group consisting of water, dimethyl sulfoxide (DMSO), hexamethylphosphoramide (HAPA), dimethylacetamide (DMAc), formamide, dimethylformamide Dimethylformamide (DMF), formic acid, N-methylmorpholine-N-oxide (NMMO), ethylene glycol, pyridine, sodium hydroxide / urea solution , An aqueous solution of potassium hydroxide / urea, an aqueous solution of ammonium hydroxide / urea, and an ionic liquid (Ionic liquid).

The pH of the polar solvent may be selected in the range of 5 to 14.

When the cellulose is immersed in the polar solvent, the temperature of the polar solvent may be selected in the range of 0 to 80 ° C.

Further, the cellulose may be immersed in a polar solvent for 0.5 to 5 hours.

Next, Swollen  Cellulose and an ammonium ion represented by Formula 1 and having a weight average molecular weight of 300 to 10,000 are mixed in the polar solvent.

For the description of the ammonium ion, refer to the description given in [microfibrous cellulose].

Sufficiently mixed so that the ammonium ion can be bound to the swollen cellulose.

The mixing can be carried out using an apparatus selected from the group consisting of a homogenizer, a quattro Taylor reactor, a high pressure homogenizer, and combinations thereof.

Subsequently, Swollen  A mixture of cellulose and the ammonium ion was prepared using a shear device Fibrillated  As the ammonium ion, Reformed Fibrous fibrous Cellulose I get a lot.

The shearing apparatus can use equipment having a high shearing force. Specifically, the shearing apparatus may be a device selected from the group consisting of a high-pressure homogenizer, a grinder, a cryocooling, ultrasonic waves, and a combination thereof.

The high-pressure homogenizer is a device that utilizes the principle that the swelled cellulose rapidly fills a thin slit at a high pressure and is subjected to a large shearing force and an impact force to be fibrillated with microfibrous cellulose.

In addition, the grinder is a device that utilizes the principle of fibrillating with a microfibrous cellulose using a shearing force and a frictional force generated by a grinding stone.

In addition, washing and separation steps of selectively obtaining the surface-modified microfibrous cellulose can be performed.

The cleaning and separation may be performed using an apparatus selected from the group consisting of a filter press, a centrifuge, a decanter, and combinations thereof.

In the above-mentioned method for producing microfine fiber cellulose, the description of the microfine fiber cellulose is described in the above description of [microfine cellulose].

The above-described method for producing microfibrous cellulose enables easy dispersion, minimizes re-aggregation, and is useful as a fine fibrous material having a high mechanical property, low thermal expansion coefficient, high specific surface area, high aspect ratio, transparency and high dimensional stability Cellulose can be produced.

The above contents will be described in more detail by the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the examples.

[ Example ]

Example  : According to the invention Fibrous fibrous  Manufacture of Cellulose

Swollen  Manufacture of Cellulose

500 ml of a 5 wt% NaOH aqueous solution and 25.0 g of pulp powder were placed in a 1,000-ml jacketed reactor connected to a homogenizer, a thermometer and a thermostat, and the mixture was stirred at 3,000 rpm for 1 hour at room temperature. , And celluloses swollen by water molecules were prepared.

Fibrous fibrous  Manufacture of Cellulose

A 5 wt% NaOH aqueous solution, 2.5 g of the above-prepared swollen cellulose and dimethyldioctadecylammonium chloride were added to a 1,000-ml jacketed reactor connected to a homogenizer, a thermometer and a thermostat, and the mixture was stirred at room temperature for 1 hour And stirred at 3,000 rpm. Subsequently, the swollen cellulose was fibrillated by applying a high shear force at a high pressure using a high-pressure homogenizer, and the -OH group of the surface of the fibrillated microfibrous cellulose was reacted with dimethyl dioctadecylammonium chloride to obtain a fibrillated smile A fibrous cellulose dispersion was prepared. The dispersion was washed with water until the pH reached 5 or more by using a filter to remove the NaOH aqueous solution. The microfibrous cellulose containing water remaining after the pH reached 5 or more was dried in a dryer at 60 캜 for 24 hours to prepare powdery microfibrous cellulose.

Comparative Example  : According to existing methods Fibrous fibrous  Manufacture of Cellulose

The swollen cellulose was prepared as described in the above examples. Thereafter, a 5 wt% NaOH aqueous solution and swollen cellulose were placed in a 1,000-ml jacketed reactor equipped with a homogenizer, a thermometer and a thermostat. Subsequently, a fibrillated microfibrillar cellulose dispersion was prepared by fibrillating the swollen cellulose by applying a shear force at a high pressure using a high pressure homogenizer. The dispersion was washed with water until the pH reached 5 or more by using a filter to remove the NaOH aqueous solution. The microfibrous cellulose containing water remaining after the pH reached 5 or more was dried in a dryer at 60 캜 for 24 hours to prepare powdery microfibrous cellulose.

Evaluation example  One : SEM  Picture

The microfibrous cellulose dispersion obtained by adding 0.05 g of the microfibrous cellulose prepared according to the above example to 10 g of pure water and then treating with a horn type ultrasonic wave for 10 minutes was mixed with 100 ml of piranha at 100 ° C mixed with sulfuric acid and hydrogen peroxide in a volume ratio of 4: The solution was sampled by spin coating on a silicon wafer treated for 10 to 15 minutes, and subjected to SEM analysis.

SEM analysis was also performed on the microfibrous cellulose produced by the above comparative example.

SEM photographs of the microfibrous cellulose prepared in the above Examples and Comparative Examples are shown in Figs. 3 and 4. Fig.

Evaluation example  2: Solvent dispersion degree

The microfibrous cellulose prepared according to the above Examples and Comparative Examples were evaluated for their dispersion stability to organic solvents such as methanol, ethyl acetate and toluene, respectively.

5 to 7 (A) show the solvent dispersion degree of the microfibrous cellulose produced by the example, and (B) show the solvent dispersion degree of the microfibrous cellulose produced by the comparative example.

FIG. 5 shows results of evaluation of dispersion stability in methanol, FIG. 6 shows the results of evaluation of dispersion stability in ethyl acetate, and FIG. 7 shows results of evaluation of dispersion stability in toluene.

As can be seen from FIGS. 5 to 7, it was confirmed that the microfibrous cellulose produced by the comparative example produced aggregates in the organic solvent.

As can be seen from the above evaluation examples 1 and 2, the hydrogen bonding is weakened due to the substitution of ammonium ions in the examples, and the efficiency of fibrillating under the same conditions is higher than that of the comparative examples. It has been confirmed that the dispersion stability in an organic solvent is excellent because it has a strong hydrophobic property due to a substituent having a hydrophobic property in the ion.

Claims (15)

delete delete delete delete delete (a) swelling cellulose by immersing it in a polar solvent;
(b) mixing the swollen cellulose with the ammonium ion represented by the following formula (1) and having a weight average molecular weight of 300 to 10,000 in the polar solvent; And
(c) fibrillating the mixture of the swollen cellulose and the ammonium ion using a shearing device to obtain a non-oxidized microfibrous cellulose in which the -OH group of the surface of the fibrillated cellulose is bonded with the ammonium ion to modify the surface thereof Comprising:
Wherein the polar solvent is any one selected from the group consisting of aqueous solutions of sodium hydroxide and urea, aqueous solutions of potassium hydroxide and urea, aqueous solutions of ammonium hydroxide and urea, and aqueous solutions of sodium hydroxide.
≪ Formula 1 >

In Formula 1,
R ₁ to R ₄ independently represent hydrogen, deuterium, C ₁ -C ₆₀ alkyl, C ₂ -C ₆₀ alkenyl, C ₂ -C ₆₀ alkynyl, C ₃ -C ₆₀ cycloalkyl, C ₃ -C ₆₀ A cycloalkenyl group or a C ₆ -C ₆₀ aryl group.
delete The method according to claim 6,
Wherein the ammonium ion has a weight average molecular weight of 500 to 5,000.
The method according to claim 6,
Wherein the ammonium ion is at least one selected from the group consisting of a secondary ammonium ion, a tertiary ammonium ion and a quaternary ammonium ion.
The method according to claim 6,
Wherein the microfibrous cellulose has a diameter of 5 nm to 100 nm and a length of 100 nm to 500 탆.
A surface-modified microfibrillated cellulose prepared according to the method of claim 6,
A surface-modified microfibrous cellulose represented by the following formula (1) and having a weight average molecular weight of 300 to 10,000:
≪ Formula 1 >

In Formula 1,
R ₁ to R ₄ independently represent hydrogen, deuterium, C ₁ -C ₆₀ alkyl, C ₂ -C ₆₀ alkenyl, C ₂ -C ₆₀ alkynyl, C ₃ -C ₆₀ cycloalkyl, C ₃ -C ₆₀ A cycloalkenyl group or a C ₆ -C ₆₀ aryl group.
12. The method of claim 11,
Wherein the ammonium ion is bonded to the -OH group of the microfibrous cellulose by electrostatic attraction.
12. The method of claim 11,
Wherein the ammonium ion has a weight average molecular weight of 500 to 5,000.
12. The method of claim 11,
Wherein the ammonium ion is at least one selected from the group consisting of a secondary ammonium ion, a tertiary ammonium ion and a quaternary ammonium ion.
12. The method of claim 11,
Wherein the microfibrous cellulose has a diameter of 5 nm to 100 nm and a length of 100 nm to 500 탆.

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