KR102411208B1 - Manufacturing Method of Cellulose Nano Fibril Using Betaine-Lactic Acid Deep Eutectic Solvent - Google Patents

Abstract

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

Description

Betaine-Lactic Acid Deep Eutectic Solvent Manufacturing Method of Cellulose Nanofibers Using Eutectic Solvent

The present invention relates to a method for preparing cellulose nanofibers using a betaine-lactic acid eutectic solvent.

Cellulose nanofibers are biomass-derived nanomaterials that are mainly obtained from wood and have enhanced physical properties when added to composites. Cellulose contained in wood, together with hemicellulose and lignin, constitutes the cell wall and intercellular layer, and these components form a complex matrix and are very resistant to depolymerization. Therefore, in order to produce cellulose nanofibers from wood, the content of hemicellulose and lignin other than cellulose contained in wood is reduced through chemical pretreatment (TEMPO catalytic oxidation, enzymes, etc.) Many efforts are being made to reduce energy consumption and time by sea island. However, since the conventional chemical pretreatment is expensive and toxic, a pretreatment method using an inexpensive, nontoxic and green solvent is required.

A deep eutectic solvent is a green solvent, attracting attention as an eco-friendly and efficient new solvent for biomass pretreatment and conversion. The eutectic solvent is a mixture of a hydrogen-bonding donor and a hydrogen-boning acceptor. The melting point of the eutectic solvent is much lower than the melting point of each component due to the strong hydrogen bond interaction between the hydrogen bond donor and the hydrogen bond acceptor. When the eutectic solvent and the biomass are mixed, the cations and anions in the eutectic solvent form strong hydrogen bonds with the hydroxyl groups of the biomass components, thereby dissolving lignocellulose. It has been reported that the eutectic solvent used for the preparation of cellulose nanofibers uses choline chloride as a hydrogen bond donor and uses carboxylic acids such as glycerol, urea or lactic acid as a hydrogen bond acceptor. However, the choline chloride has a disadvantage that requires post-treatment of the reaction solution produced after biomass treatment. Therefore, it is judged that economical mass production of cellulose nanofibers will be possible if a eutectic solvent having a pretreatment effect similar to the choline chloride-based eutectic solvent and having a low post-treatment cost is developed.

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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The present invention is to solve the above problems and provides a betaine-lactic acid eutectic solvent using an amino acid betaine as a hydrogen bond acceptor and lactic acid as a hydrogen bond donor, By optimizing the composition and reaction conditions for pretreatment of wood using the eutectic solvent, an environmentally friendly new eutectic solvent for manufacturing cellulose nanofibers that can replace the conventional choline chloride-based eutectic solvent and a method for manufacturing cellulose nanofibers using the same but it has a purpose.

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 fine wood flour with a betaine-lactic acid deep eutectic solvent, and pulverizing and dissolving the pre-treated fine wood flour to prepare cellulose nano fibers It provides a method for producing cellulose nanofibers using a betaine-lactic acid eutectic solvent.

The betaine-lactic acid eutectic is prepared by mixing betaine and lactic acid in a molar ratio of 1: 0.5 to 7, and betaine is used as a hydrogen bond acceptor and lactic acid is used as a hydrogen bond donor.

The fine wood flour is pre-treated by stirring at 90 to 150° C. for 6 to 36 hours after the betaine-lactic acid eutectic solvent is added. Mechanical treatment is performed with a niger to form nanofibers. The pretreated fine wood flour is characterized in that the lignin content is 18 to 22%, and the cellulose nanofibers prepared by mechanical treatment using a high-speed blender and a high-pressure homogenizer have a diameter of 28 to 35 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 betaine-lactic acid eutectic solvent. The cellulose nanofiber sheet has a tensile strength of 20 to 50 MPa and an elastic modulus of 3.5 to 7 MPa.

In the method for producing cellulose nanofibers using the betaine-lactic acid eutectic solvent of the present invention, since the fine wood flour is pretreated with the betaine-lactic acid eutectic solvent, the efficiency of mechanical pulverization and fibrillation is increased, thereby producing homogeneous cellulose nanofibers with a small diameter. There are advantages that can be The betaine-lactic acid eutectic of the present invention is a cationic eutectic solvent that can disrupt strong hydrogen bonds of biomass components, improve the production efficiency of cellulose nanofibers with a high-pressure homogenizer, and reduce energy consumption. There are advantages. In particular, betaine, a hydrogen bond acceptor of the present invention, can be easily removed simply by washing the pretreated fine wood flour with distilled water, and has an economical advantage compared to the conventional eutectic solvent using choline chloride.

Figure 1 shows the manufacturing step of the cellulose nanofibers using the betaine-lactate eutectic solvent of the present invention.
Figure 2 shows the weight reduction rate of pine fine wood flour according to the betaine-lactic acid eutectic solvent treatment of the present invention.
3 shows the results of observation of CNFs prepared using the betaine-lactic acid 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 comprises the steps of pre-treating fine wood flour with a betaine-lactic acid deep eutectic solvent, and pulverizing and dissolving the pre-treated fine wood flour to prepare cellulose nanofibril. Provided is a method for producing cellulose nanofibers using a betaine-lactic acid eutectic solvent.

The step of pre-treating the fine wood flour of the present invention with a betaine-lactic acid eutectic solvent breaks the strong ether and hydrogen bonds existing between lignin, haemicellulose, and cellulose of the fine wood flour, thereby improving the mechanical grinding and dissolving efficiency of the fine wood flour. It is a process for

The pretreatment of the fine wood flour with a betaine-lactic acid eutectic solvent is a first step of pulverizing wood chips to produce fine wood flour, and a second step of preparing a eutectic solvent mixture by mixing the fine wood flour and the betaine-lactic acid eutectic solvent 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 do.

The eutectic solvent is characterized in that betaine and lactic acid are mixed in a molar ratio of 1: 0.5 to 7. The betaine is ionized to act as a hydrogen bond acceptor, and the lactic acid acts as a hydrogen bond donor. Therefore, when the betaine and lactic acid are mixed with the fine wood flour, the strong bonding force between the lignin, haemi cellulose and cellulose of the fine wood flour is relieved, and the lignin is dissolved and removed compared to other components, so Disassembly and fiberization are facilitated. When the molar ratio of betaine and lactic acid is less than 1:0.5, the solubility improvement effect of fine wood flour is insignificant because the hydrogen bond donor is too small. does not increase Preferably, the molar ratio of the betaine and lactic acid is 1:0.8 to 5. More preferably, it is 1:1.

The 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. When the particle size of the fine wood flour is less than 100 mesh, the yield of wood flour is very low. When the particle size of the fine wood flour exceeds 20 mesh, the particle size is too large and the surface area is small, so the reaction time must be increased.

The eutectic mixture prepared by mixing the fine wood flour and the betaine-lactic acid 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 solvent mixture, the betaine and lactic acid eutectic solvent 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 carried out 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 betaine-lactic acid eutectic solvent is stirred at 120 to 140° C. for 12 to 28 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. When 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 pre-treated fine wood flour is manufactured into cellulose nanofibril through mechanical pulverization and defibration.

The step of pulverizing and dissolving the pretreated fine wood flour to prepare cellulose nanofibril is a eutectic solvent reaction by adding distilled water to the pretreated 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 a pulverized product and a seventh step of preparing cellulose nano fibers by dissolving the eutectic solvent reaction pulverized product with a high-pressure homogenizer.

The pre-treated fine wood flour has a lignin content of 18 to 22% 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 dissolved 1 to 5 times at a pressure of 15,000 to 25,000 psi using a high-pressure homogenizer. When this is done, cellulose nanofibers having a diameter of 28 to 35 nm are prepared.

When the lignin content of the pre-treated fine wood flour exceeds 22%, there is a disadvantage in that more time is required for grinding and dissolving 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 28 to 35 nm, and the cellulose nanofiber sheet has a tensile strength of 20 to 50 MPa and an elastic modulus of 3.5 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

A betaine-lactic-acid-based eutectic solvent for CNF production (hereinafter, betaine-lactic acid eutectic solvent) is prepared by mixing betaine and lactic acid in a molar ratio of 1:1, 1:2, and 1:5. did According to the molar ratio, betaine-lactic acid eutectic solvent (1/1), betaine-lactic acid eutectic solvent (1/2), or betaine-lactic acid eutectic solvent (1/5) 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 betaine-lactic acid 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 betaine-lactic acid eutectic solvent was added to 2 g of pine fine wood flour to prepare a betaine-lactic acid eutectic solvent mixture.

The betaine-lactic acid eutectic mixture is put 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 betaine-lactic acid eutectic reactant did

The betaine-lactic acid 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 betaine-lactic acid eutectic reactant to adjust the concentration to 1%. Thereafter, the mixture was coarsely pulverized for 15 minutes in a high-speed blender rotating at a speed of 35,000 rpm to prepare a betaine-lactic acid eutectic solvent reaction pulverized product. The betaine-lactic acid eutectic solvent reaction pulverized product was prepared by a method of repeating fibrillation 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 fission 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 betaine-lactic acid 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 Betaine: Lactic acid = 1:1 100℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 2 Betaine:lactic acid=1:2 100℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 3 Betaine:Lactate=1:5 100℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 4 Betaine: Lactic acid = 1:1 120℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 5 Betaine:lactic acid=1:2 120℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 6 Betaine:Lactate=1:5 120℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 7 Betaine: Lactic acid = 1:1 130℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 8 Betaine:lactic acid=1:2 130℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 9 Betaine:Lactate=1:5 130℃ 24 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 10 Betaine: Lactic acid = 1:1 130℃ 6 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 11 Betaine: Lactic acid = 1:1 130℃ 12 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 12 Betaine:lactic acid=1:2 130℃ 6 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 13 Betaine:lactic acid=1:2 130℃ 12 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 14 Betaine:Lactate=1:5 130℃ 6 hours high-speed blender
(35,000rpm) high pressure homogenizer
(20,000 psi, 5 reps) Example 15 Betaine:Lactate=1:5 130℃ 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 betaine-lactic acid eutectic solvent treatment of the present invention. According to FIG. 2, as a result of adding and reacting a betaine-lactic acid eutectic solvent to pine wood flour, it was confirmed that the weight loss 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 a betaine-lactic acid eutectic solvent (1/1).

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 Betaine: Lactic acid = 1:1 100℃ 24 hours 52.7 19.1 28.2 Example 10 Betaine: Lactic acid = 1:1 130℃ 6 hours 52.6 19.6 27.8 Example 7 Betaine: Lactic acid = 1:1 130℃ 24 hours 58.9 20.7 20.4

It was confirmed that Examples 1, 7 and 10 in which the betaine-lactic acid eutectic was used had significantly lower lignin content than Comparative Example 1 in which the eutectic was not used (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 betaine-lactic acid eutectic (1/1), it was observed that nanonized CNFs were present in a uniform form, whereas in Comparative Example 2 treated with a choline chloride-urea eutectic solvent, nanosized It is confirmed that CNF and non-nanoized CNF coexist.

Example: Cellulose nanofiber sheet containing cellulose nanofibers prepared with betaine-lactic acid-based eutectic solvent for preparing 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 33.0±5.3 30.2±4.8 Filtration time (sec) 26 3600 140 162 Tensile strength of nano paper (MPa) 11.4±10.4 14.6±3.5 23.2±2.8 43.1±6.8 Modulus of elasticity of nano paper (MPa) 3.4±0.2 1.2±1.1 3.6±0.5 5.0±0.6

Nanopaper prepared using betaine-lactic acid eutectic solvent (Examples 16 and 17) was prepared using CNF prepared by mechanical grinding and fibrillation only (Comparative Example 3) without using a eutectic solvent. In contrast, it was confirmed that the tensile strength increased by about 2-4 times. This is considered to be the result of improved hydrogen bonding between cellulose nanofibers because the content of hydrophobic lignin was reduced through treatment with betaine and lactic acid eutectic.

As a result of the improvement of the efficiency of mechanical fibrillation through the betaine-lactic acid eutectic solvent 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 the average diameter was very large compared to CNFs prepared with betaine and lactic acid eutectic (Examples 7 and 10). In addition, the tensile strength and modulus of the nanopaper prepared with choline chloride-urea eutectic solvent-treated CNF (Comparative Example 2) was compared to the nanopaper prepared with betaine-lactic acid eutectic solvent-treated CNF (Examples 16 and 17). appeared to be remarkably low. This means that betaine-lactate eutectic improves the efficiency of CNF fibrillation compared to choline chloride-urea eutectic.

Therefore, the betaine-lactic acid eutectic solvent of the present invention using betaine as the hydrogen bond acceptor and lactic acid 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 betaine-lactic acid eutectic solvent of the present invention can replace the conventional choline chloride-based eutectic solvent, and the hydrogen bond acceptor of the present invention, betaine, has a simple post-treatment process and thus the production cost is also reduced. It is thought that it can be done

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 compared with the weight of pine fine wood meal before treatment to calculate the weight reduction rate. The lignin content (Klason lignin %) was evaluated by applying the Klason lignin method using 72% sulfuric acid to the pine wood flour 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 used.

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)

Betaine comprising the steps of pre-treating fine wood flour with a betaine-lactic acid deep eutectic solvent, and pulverizing and dissolving the pre-treated fine wood flour to prepare cellulose nano fibers -A method of manufacturing cellulose nanofibers using a lactic acid eutectic solvent,
The pretreatment is betaine, characterized in that the fine wood flour is mixed with a betaine-lactic acid eutectic solvent prepared by mixing betaine and lactic acid in a molar ratio of 1:1, and then reacted at 120 to 140° C. for 12 to 28 hours. -Method for producing cellulose nanofibers using lactic acid eutectic solvent.
The method of claim 1, wherein the betaine is used as a hydrogen bond acceptor and the lactic acid is used as a hydrogen bond donor.
The method of claim 1, wherein the pretreatment of the fine wood flour with a betaine-lactic acid 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 betaine-lactic acid eutectic solvent;
a third step of preparing a eutectic reactant by stirring the eutectic mixture at 120 to 140° C. for 12 to 28 hours; and
a fourth step of filtering the eutectic reactant to obtain a solid pretreated fine wood flour;
A method for producing cellulose nanofibers using a betaine-lactic acid eutectic solvent, comprising:
delete According to claim 1, wherein the step of pulverizing and dissolving the pre-treated fine wood flour to prepare cellulose nano fibers (cellulose nano fibril);
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 manufacturing cellulose nano fibers by fibrillating the eutectic solvent reaction pulverized product with a high-pressure homogenizer;
A method for producing cellulose nanofibers using a betaine-lactic acid eutectic solvent, comprising:
[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 18 to 22%.
The method of claim 1, wherein the cellulose nanofibers have a diameter of 28 to 35 nm.
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