KR102394467B1 - Manufacturing Method of Cellulose Nano Fibril Using Potassium Carbonate-Glycerol Deep Eutectic Solvent - Google Patents

Abstract

In the method for producing cellulose nanofibers using the potassium carbonate-glycerol eutectic of the present invention, since the fine wood flour is pretreated with the potassium carbonate-glycerol eutectic solvent, the efficiency of mechanical pulverization and fibrillation is increased to produce homogeneous cellulose nanofibers with a small diameter. There are advantages that can be Potassium carbonate, which is a hydrogen bond acceptor of the present invention, can be easily removed by simply washing the pretreated fine wood flour with distilled water, and has an economical advantage compared to the conventional eutectic solvent using choline chloride.

Description

Potassium Carbonate-Manufacturing Method of Cellulose Nano Fiber Using Eutectic Solvent of Potassium Carbonate-Glycerol

The present invention relates to a method for producing cellulose nanofibers using a potassium carbonate-glycerol eutectic solvent.

Cellulose fibers (cellulose fibril) are classified into cellulose nanofibers (CNF) and cellulose nanocrystals (CNC) according to the manufacturing method. CNF is mainly obtained from biomass through mechanical treatment, and refers to microfine fibers having a diameter (width) of 5 to 100 nm and a length of several tens of μm. On the other hand, CNC is mainly obtained through chemical treatment by acid hydrolysis, and is distinguished from CNF as a stick-shaped, high-crystal material with a diameter (width) of 2 to 20 nm and a length of 100 to 600 nm.

CNF is attracting attention as a lightweight composite material due to its high aspect ratio and high strength properties to light weight. In addition, cellulose nanofibers can be used as packaging materials for food and medicine due to their low air permeability, excellent mechanical and optical properties, and have high potential for use in lithium ion separators, displays, electronic papers, and sensors.

Mechanical methods used for the production of cellulose nanofibers have a problem in that economic efficiency is lowered due to high energy consumption. Accordingly, a method of performing chemical pretreatment on cellulose fibers is being developed as a method to reduce mechanical treatment time and improve defibration efficiency. As the chemical pretreatment method, there are a TEMPO catalytic oxidation method, a carboxymethylation method, and a method of treating a deep eutetic solvent.

Eutectic solvents are prepared as eutectic mixtures of Lewis or Bronsted acids and salts containing various kinds of cations or anions. The eutectic solvent is formed by strong hydrogen bonds between constituent materials, so it has many excellent characteristics such as biodegradability, low toxicity, low production cost, and ease of synthesis compared to ionic liquid solvents and conventional organic solvents.

When the eutectic solvent is treated with the biomass, the ether bonds and hydrogen bonds of the biomass components can be effectively dissolved and dissolved, so that delignification is easily possible by separating cellulose from lignin and hemicellulose.

Therefore, when the biomass is pretreated using the eutectic solvent, a biomass reactant containing a high content of cellulose can be obtained, which improves the degree of nanofibrillation of cellulose due to mechanical treatment.

However, since the conventional choline chloride-based eutectic solvent uses a strong salt such as chlorine ion, a large amount of water is required to remove the salt from the biomass after treatment, thereby increasing the cost.

The patents and references mentioned in this specification are hereby incorporated by reference to the same extent as if each publication were individually and expressly specified by reference.

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In order to solve the above problems, the present invention provides a potassium carbonate-glycerol eutectic solvent capable of obtaining a similar pretreatment effect at a lower process cost than a conventional choline chloride-based eutectic solvent and a method for producing cellulose nanofibers using the same It is intended to provide

Other objects and technical features of the present invention are more specifically set forth by the following detailed description of the invention, claims and drawings.

The present invention includes the steps of pre-treating pine fine wood flour with a potassium carbonate-glycerol deep eutectic solvent and pulverizing and dissolving the pre-treated pine fine wood flour to prepare cellulose nanofibril. It provides a method for producing cellulose nanofibers using a potassium carbonate-glycerol eutectic solvent containing.

Potassium carbonate of the potassium carbonate-glycerol eutectic solvent is prepared by mixing potassium carbonate and glycerol in a molar ratio of 1: 2 to 10, potassium carbonate is used as a hydrogen bond acceptor, and glycerol is used as a hydrogen bond donor.

The pine fine wood flour is pretreated by stirring at 100 to 130° C. for 6 to 24 hours after the potassium carbonate-glycerol eutectic solvent is added, and a high-speed blender at a speed of 30,000 to 40,000 rpm and a high-pressure homogenizer at a pressure of 15,000 to 25,000 psi. Mechanical fibrillation is performed with a generator to form nanofibers. The pretreated fine wood flour is characterized in that the lignin content is 17 to 26%, and the cellulose nanofibers prepared by mechanical treatment using a high-speed blender and a high-pressure homogenizer have a diameter of 28 to 28 nm.

The present invention provides a cellulose nanofiber sheet prepared by hot pressure and compression dehydration of cellulose nanofibers prepared through a method for manufacturing cellulose nanofibers using a potassium carbonate-glycerol eutectic solvent. The cellulose nanofiber sheet has a tensile strength of 42 to 52 MPa and an elastic modulus of 4.5 to 7 MPa.

In the method for producing cellulose nanofibers using the potassium carbonate-glycerol eutectic solvent of the present invention, the efficiency of mechanical pulverization and fibrillation is increased because pine fine wood flour is pretreated with the potassium carbonate-glycerol eutectic solvent, thereby producing a homogeneous cellulose nanofiber with a small diameter There are advantages to doing. Potassium carbonate, which is a hydrogen bond acceptor of the present invention, can be easily removed by simply washing the pretreated fine wood flour with distilled water, and since the process cost is low compared to the conventional eutectic solvent using choline chloride, cellulose nanofibers are economically manufactured There is an advantage to

Figure 1 shows the manufacturing step of the cellulose nanofiber using the potassium carbonate-glycerol eutectic of the present invention.
Figure 2 shows the weight reduction rate of pine fine wood flour according to the potassium carbonate-glycerol eutectic solvent treatment of the present invention.
3 shows the results of observation of CNF prepared using the potassium carbonate-glycerol eutectic and choline chloride-urea eutectic of the present invention with a scanning electron microscope (SEM) and a projection electron microscope (TEM). Panel A) shows that the CNF of Example 7 was photographed with a scanning electron microscope, and panel B) shows that the CNF of Example 7 was photographed with a scanning electron microscope. Panel C) shows that the CNF of Comparative Example 2 was photographed with a scanning electron microscope, and panel D) shows that the CNF of Comparative Example 2 was photographed with a scanning electron microscope.

The present invention includes the steps of pre-treating pine wood flour with a potassium carbonate-glycerol deep eutectic solvent, and pulverizing and dissolving the pre-treated fine wood flour to prepare cellulose nanofibril It provides a method for producing cellulose nanofibers using a potassium carbonate-glycerol eutectic solvent.

The step of pretreating the pine fine wood flour of the present invention with a potassium carbonate-glycerol eutectic solvent breaks the strong ether and hydrogen bonds existing between the lignin, haemi cellulose, and cellulose of the fine wood flour, so that the mechanical grinding and dissolving efficiency of the pine fine wood flour is improved. It is a process to improve.

The step of pre-treating the pine fine wood flour with a potassium carbonate-glycerol eutectic solvent is a first step of pulverizing the wood chips to produce fine wood flour, mixing the fine wood flour with the potassium carbonate-glycerol eutectic solvent to prepare a eutectic solvent mixture Step 2, a third step of preparing a eutectic reactant by stirring the eutectic mixture at 100 to 130° C. for 6 to 24 hours, and a fourth step of filtering the eutectic reactant to obtain a solid pretreated fine wood flour include

The eutectic solvent is characterized in that potassium carbonate and glycerol are mixed in a molar ratio of 1: 2 to 10. The potassium carbonate is ionized to act as a hydrogen bond acceptor, and the glycerol acts as a hydrogen bond donor. Therefore, when the potassium carbonate and glycerol are mixed with the fine wood flour, the solubility of components of the fine wood flour is improved by breaking the strong ether and hydrogen bonds of lignin, haemi cellulose, and cellulose in the fine wood flour. If the molar ratio of potassium carbonate to glycerol is less than 1:2, the effect of improving the solubility of fine wood flour is insignificant because the hydrogen bond donor is too small. does not increase Preferably, the molar ratio of potassium carbonate to glycerol is 1:4.

The pine fine wood powder is manufactured by mechanically pulverizing wood chips, and the particle size is characterized in that it corresponds to 100 to 20 mesh. The mesh refers to a sample in which more than 90% of particles pass through a sieve of a certain size. 20 mesh relates to a sieve having a diameter of 0.9 mm, and 100 mesh relates to a sieve having a diameter of 0.15 mm. If the particle size of the fine wood flour is less than 100 mesh, the particles are too small and easily agglomerate, so the reaction efficiency may be rather reduced. The downside is that it needs to be increased.

The eutectic mixture prepared by mixing the pine wood flour and the potassium carbonate-glycerol eutectic is stirred at 90 to 150° C. for 6 to 36 hours to prepare a eutectic reactant.

By stirring while applying heat to the eutectic mixture, the potassium carbonate-glycerol eutectic can easily penetrate into the structure of the fine wood flour. If the reaction temperature is less than 90 ℃, the reaction time should be further increased, and even if the reaction temperature exceeds 150 ℃, there is no difference in the minimum reaction time. If the reaction time is less than 6 hours, even if the reaction is performed at 150° C., the pretreatment of the fine wood flour is insufficient, and the nanofibrillation due to the mechanical treatment of cellulose may be reduced. Even if the reaction time exceeds 36 hours, the degree of pretreatment does not increase significantly. Preferably, the eutectic mixture prepared by mixing the fine wood flour and the potassium carbonate-glycerol eutectic is stirred at 100 to 130° C. for 6 to 24 hours to prepare a eutectic reactant, and more preferably at 130° C. for 24 hours. stir while

The eutectic solvent reactant is filtered to obtain only a solid reactant, which is washed with water to prepare pretreated fine wood flour. If the fine wood flour in which the reaction has been performed is washed with distilled water, the overall weight of the fine wood flour is reduced because cellulose, hemicellulose and lignin, which are components of the fine wood flour, are reduced.

The prepared pre-treated fine wood flour is prepared into cellulose nanofibril through mechanical pulverization and defibration.

In detail, the step of producing cellulose nanofibril by pulverizing and dissolving the pre-treated fine wood flour is performed by adding distilled water to the pre-treated fine wood flour and coarsely pulverizing it using a high-speed blender at a speed of 30,000 to 40,000 rpm. A sixth step of preparing the eutectic reaction pulverized product and a seventh step of preparing cellulose nanofibril by dissolving the eutectic solvent reaction pulverized product with a high-pressure homogenizer. The pre-treated pine fine wood flour has a lignin content of 17 to 26% and is pulverized for 10 to 20 minutes with a high-speed blender at a speed of 30,000 to 40,000 rpm, and then 1 to 5 times at a pressure of 15,000 to 25,000 psi using a high-pressure homogenizer. When fibrillated, cellulose nanofibers having a diameter of 25 to 28 nm are prepared.

When the lignin content of the pretreated pine fine wood flour exceeds 26%, there is a disadvantage in that more time is required for pulverization and dissolution using a high-speed blender and a high-pressure homogenizer.

If the rotation speed of the high-speed blender is less than 30,000 rpm, the removal of the lignin remaining after the eutectic solvent reaction is insufficient, and thus the purity of the cellulose nanofibers may be reduced, and the removal of the lignin may be insufficient even if the grinding time is further input. Even if the rotational speed of the high-speed blender exceeds 40,000 rpm, the lignin removal effect is not greatly improved, but rather excessive heat may be generated and the cellulose particles may be deformed.

If the pressure of the high-pressure homogenizer is less than 15,000 psi, the homogeneity of the cellulose nanofibers may be reduced, and even if the pressure of the high-pressure homogenizer exceeds 25,000 psi, the diameter of the cellulose nanofibers does not become smaller.

The present invention provides a cellulose nanofiber sheet prepared by hot pressure and compression dehydration of the cellulose nanofiber prepared by the above manufacturing method. The cellulose nanofiber has a diameter of 25 to 28 nm, and the cellulose nanofiber sheet has a tensile strength of 42 to 52 MPa and an elastic modulus of 4.5 to 7 MPa.

The cellulose nanofiber sheet can be manufactured as an industrial high-functional separator, high-performance filter, battery separetta, transparent film, etc. as a method of controlling transparency, spatiality and specific surface area, and is coated on paper or film to prevent the passage of oxygen or gas It may be manufactured as a controllable packaging container or the like.

The present invention will be described in detail through the following examples.

Example

Example: Preparation of nanocellulose using a eutectic solvent

1) Preparation of fine wood flour for pine trees

For the production of cellulose nano fibril (CNF), pine wood chips were prepared and pulverized to prepare fine wood powder for pine trees. The fine pine wood powder was pulverized to a particle size of 40 to 80 mesh using a grinder.

2) Preparation of eutectic solvent

Potassium carbonate-glycerol-based eutectic solvent for CNF production (hereinafter, potassium carbonate-glycerol eutectic solvent) was prepared by mixing potassium carbonate and glycerol in a molar ratio of 1:4, 1:5, and 1:7. . According to the molar ratio, potassium carbonate-glycerol eutectic solvent (1/4), potassium carbonate-glycerol eutectic solvent (1/5), or potassium carbonate-glycerol eutectic solvent (1/7) was named.

A choline chloride-urea-based eutectic solvent for CNF production (hereinafter, choline chloride-urea eutectic solvent) was prepared by mixing choline chloride and urea in a molar ratio of 1:2.

3) Preparation of CNF using eutectic solvent

As an example, CNF was prepared using a potassium carbonate-glycerol eutectic solvent. As a comparative example, CNF was prepared only by mechanical grinding and fibrillation without treatment with a eutectic solvent. As another comparative example, CNF was prepared using a choline chloride-urea eutectic solvent.

98 g of the potassium carbonate-glycerol eutectic was added to 2 g of pine fine wood flour to prepare a potassium carbonate-glycerol eutectic mixture.

The potassium carbonate-glycerol eutectic mixture is placed in a flask and reacted with stirring at 100°C, 120°C, or 130°C for 6 hours, 12 hours, or 24 hours using an oil bath to prepare a potassium carbonate-glycerol eutectic reactant did

The potassium carbonate-glycerol eutectic reactant was filtered to obtain a solid phase, which was first washed with 1,4-dioxane/water (4/1) through reduced pressure filtration, followed by second washing with distilled water.

Distilled water was added to the obtained solid potassium carbonate-glycerol eutectic reactant to adjust the concentration to 1%. After that, it was coarsely pulverized in a high-speed blender rotating at a speed of 35,000 rpm for 15 minutes to prepare a reaction pulverized product of potassium carbonate-glycerol eutectic solvent. The potassium carbonate-glycerol eutectic solvent reaction pulverized product was prepared by a method of defibrillation up to 5 times at a pressure of 20,000 psi in a high-pressure homogenizer.

When the eutectic solvent was not used, distilled water was added to the prepared pine fine wood powder to adjust the concentration to 1%. Then, it was coarsely pulverized for 15 minutes in a high-speed blender rotating at a speed of 35,000 rpm. CNF was prepared by the method. If large particles of wood powder that cause nozzle clogging of the high-pressure homogenizer were found during the fibrillation process, they were appropriately removed.

When a choline chloride-urea eutectic is used as the eutectic solvent, CNF is prepared in the same manner as in the case of using a potassium carbonate-glycerol eutectic, but the reaction conditions of pine fine wood flour and choline chloride-urea eutectic are at 100° C. for 6 hours. The reaction was fixed.

Table 1 below shows the CNF manufacturing conditions of Examples and Comparative Examples of the present invention.

eutectic solvent reaction temperature reaction time smash seasum Comparative Example 1 doesn't exist doesn't exist doesn't exist high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Comparative Example 2 Choline Chloride:Urea=1:2 100℃ 6 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 1 Potassium carbonate: glycerol = 1:4 100℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 2 Potassium carbonate: glycerol = 1:5 100℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 3 Potassium carbonate: glycerol = 1:7 100℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 4 Potassium carbonate: glycerol = 1:4 120℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 5 Potassium carbonate: glycerol = 1:5 120℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 6 Potassium carbonate: glycerol = 1:7 120℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 7 Potassium carbonate: glycerol = 1:4 130℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 8 Potassium carbonate: glycerol = 1:5 130℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 9 Potassium carbonate: glycerol = 1:7 130℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 10 Potassium carbonate: glycerol = 1:4 130℃ 6 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 11 Potassium carbonate: glycerol = 1:4 130℃ 12 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 12 Potassium carbonate: glycerol = 1:5 130℃ 6 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 13 Potassium carbonate: glycerol = 1:5 130℃ 12 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 14 Potassium carbonate: glycerol = 1:7 130℃ 6 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 15 Potassium carbonate: glycerol = 1:7 130℃ 12 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps)

Figure 2 shows the weight reduction rate of pine fine wood flour according to the potassium carbonate-glycerol eutectic solvent treatment of the present invention. According to FIG. 2, as a result of adding and reacting a potassium carbonate-glycerol eutectic solvent to pine wood flour, it was confirmed that the weight reduction rate increased as the reaction temperature and reaction time increased.

Table 2 below shows the content of components measured after treatment by controlling the reaction temperature and reaction time under the conditions of using potassium carbonate-glycerol eutectic (1/4).

eutectic solvent reaction temperature reaction time Chemical composition (%) Cellulose Hemicellulose Klason lignin Comparative Example 1 N/A - - 44.9 23.8 31.3 Comparative Example 2 Choline Chloride:Urea=1:2 100℃ 6 hours 42.3 19.2 27.4 Example 1 Potassium carbonate: glycerol = 1:4 100℃ 24 hours 53.6 20.9 25.5 Example 10 Potassium carbonate: glycerol = 1:4 130℃ 6 hours 54.8 20.1 25.1 Example 7 Potassium carbonate: glycerol = 1:4 130℃ 24 hours 63.1 19.5 17.4

It was confirmed that Examples 1, 7, and 10 using the potassium carbonate-glycerol eutectic had significantly lower lignin content compared to Comparative Example 1 which did not use the eutectic solvent (see Table 2). In particular, the content of lignin decreased as the reaction temperature and reaction time increased.

3 shows the results of observation of CNFs of Example 7 and Comparative Example 2 of the present invention with a scanning electron microscope (SEM) and a projection electron microscope (TEM). As a result of observation, in the case of Example 7 treated with a potassium carbonate-glycerol eutectic (1/4), it was observed that nanonized CNFs were present in a uniform form, whereas in Comparative Example 2 treated with a choline chloride-urea eutectic, it was nanosized It is confirmed that CNF and non-nanoized CNF are mixed.

Example: Cellulose nanofiber sheet containing cellulose nanofibers prepared with a eutectic solvent for producing potassium carbonate-glycerol-based nanocellulose

Cellulose nanofiber sheets (hereinafter, nanopaper) were prepared using the CNFs prepared in Comparative Examples 1, 2, 7 and 10, and tensile properties were measured. The tensile properties are tensile strength and elastic modulus. The nanopaper was prepared by filtration under reduced pressure of the prepared CNF, followed by hot pressure and compression dehydration at 105°C.

Table 3 below shows the physical properties of CNFs prepared in Comparative Examples 1, 2, 7 and 10, and the tensile properties of nanopaper prepared using the same.

item Comparative Example 3 Comparative Example 4 Example 16 Example 17 CNF used to make nanopaper Comparative Example 1 Comparative Example 2 Example 10 Example 7 The number of times of high-pressure homogenizer fission 5 5 5 5 Average diameter of CNF (nm) 323±77 145.6±52.6 27.6±2.4 25.4±2.7 Filtration time (sec) 26 3600 154 169 Tensile strength of nano paper (MPa) 11.4±10.4 14.6±3.5 43.7±6.7 51.7±7.2 Modulus of elasticity of nano paper (MPa) 3.4±0.2 1.2±1.1 4.8±0.5 6.0±0.4

Nanopaper prepared using potassium carbonate-glycerol eutectic solvent (Examples 16 and 17) was prepared using CNF prepared only by mechanical grinding and fibrillation without using a eutectic solvent (Comparative Example 3). In contrast, it was confirmed that the tensile strength increased by about 4-5 times. This is considered to be the result of improved hydrogen bonding between the cellulose nanofibers because the content of hydrophobic lignin was reduced through the calcium carbonate-glycerol eutectic treatment.

As a result of improving the efficiency of mechanical fibrillation through the calcium carbonate-glycerol eutectic treatment, it was confirmed that the diameter of CNFs (Examples 7 and 10) became smaller and the homogeneity of CNFs was also improved. When nano-paper is manufactured using CNF having a small diameter and homogeneity, the CNF is densely located inside the nano-paper, which leads to the improvement of hydrogen bonding force, which is judged to improve the tensile properties of the nano-paper.

Comparative Example 4 was CNF prepared with choline chloride-urea eutectic, and had a very large average diameter compared to CNF prepared with potassium carbonate-glycerol eutectic (Examples 7 and 10). In addition, the tensile strength and modulus of the nanopaper prepared with choline chloride-urea eutectic-treated CNF (Comparative Example 2) was compared to the nanopaper prepared with calcium carbonate-glycerol eutectic-treated CNF (Examples 16 and 17). appeared remarkably low. This means that the calcium carbonate-glycerol eutectic improves the efficiency of CNF fibrillation compared to the choline chloride-urea eutectic.

Therefore, the potassium carbonate-glycerol eutectic solvent of the present invention using potassium carbonate as the hydrogen bond acceptor and glycerol as the hydrogen bond donor is compared to the choline chloride-urea eutectic solvent using choline chloride as the hydrogen bond acceptor and urea as the hydrogen bond donor. Therefore, it is judged to show better performance as a eutectic solvent for CNF production.

Based on the above results, it is determined that the potassium carbonate-glycerol eutectic of the present invention can replace the conventional choline chloride-based eutectic, and potassium carbonate, which is a hydrogen bond acceptor of the present invention, is compared to the conventional choline chloride in the post-treatment process It is judged that the simplicity of this can also reduce the production cost.

Experimental example: analysis of weight loss rate, lignin content, cellulose content

The weight of pine fine wood meal treated with eutectic solvent was measured, and the weight reduction rate was calculated by comparing it with the weight of pine fine wood meal before treatment. The lignin content (Klason lignin %) was evaluated by applying the Klason lignin method using 72% sulfuric acid to the pine wood meal treated with the eutectic solvent. The hemicellulose and cellulose contents of the residue were evaluated by preparing holocellulose through sodium chlorite-acetic acid method (aka Wise method or SA treatment) and removing haemicellulose through 17.5% NaOH treatment.

The shape of the CNFs manufactured with a high-speed blender and a high-pressure homogenizer was observed using a scanning electron microscope (SEM) and a transmission electron microscopy (TEM). was measured using

The cellulose nanofiber sheet (nano paper) was analyzed using Hounsfield Test Equipment (Redhill, UK) after cutting to a size of 5 × 0.4 to 0.6 × 70 mm (width × thickness × length). The tensile properties were measured at a crosshead speed of 5 mm/min at a span length of 30 mm using a universal testing machine.

Specific examples described herein are meant to represent preferred embodiments or examples of the present invention, and the scope of the present invention is not limited thereby. It will be apparent to those skilled in the art that modifications and other uses of the present invention do not depart from the scope of the invention as set forth in the claims herein.

Claims (10)

Potassium carbonate comprising the steps of pretreating fine wood flour with a potassium carbonate-glycerol deep eutectic solvent and preparing cellulose nano fibers by pulverizing and dissolving the pretreated fine wood flour - A method for producing cellulose nanofibers using a glycerol eutectic solvent.
The method of claim 1, wherein the potassium carbonate is used as a hydrogen bond acceptor and the glycerol is used as a hydrogen bond donor.
The method of claim 1, wherein the pretreatment of the fine wood flour with a potassium carbonate-glycerol eutectic solvent;
The first step of pulverizing wood chips to produce fine wood flour:
a second step of preparing a eutectic solvent mixture by mixing the fine wood flour and the potassium carbonate-glycerol eutectic;
a third step of preparing a eutectic reactant by stirring the eutectic mixture at 90 to 150° C. for 6 to 36 hours; and
a fourth step of filtering the eutectic reactant to obtain a solid pretreated fine wood flour;
Potassium carbonate, characterized in that it comprises a method for producing cellulose nanofibers using a glycerol eutectic solvent.
[Claim 4] The method of claim 3, wherein the potassium carbonate-glycerol eutectic is potassium carbonate and glycerol in a molar ratio of 1: 2-10.
The method of claim 1, wherein the preparing of cellulose nano fibers by grinding and dissolving the pre-treated fine wood flour comprises;
a sixth step of adding distilled water to the pre-treated fine wood flour and coarsely pulverizing it using a high-speed blender at a speed of 30,000 to 40,000 rpm to prepare a eutectic solvent reaction pulverized product; and
a seventh step of preparing cellulose nano fibers by defibrating the eutectic solvent reaction pulverized product with a high-pressure homogenizer;
Potassium carbonate, characterized in that it comprises a method for producing cellulose nanofibers using a glycerol eutectic solvent.
[Claim 6] The method of claim 5, wherein the high-pressure homogenizer is defibrillated 1 to 5 times at a pressure of 15,000 to 25,000 psi.
[Claim 6] The method of claim 5, wherein the pretreated fine wood flour has a lignin content of 17 to 26%.
The method of claim 1, wherein the cellulose nanofibers have a diameter of 28 to 28 nm.
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