KR102588704B1 - Method for manufacturing cellulose microfiber and cellulose microfiber manufactured by the same - Google Patents

Abstract

The present invention relates to a method for producing cellulose microfibers in an economical and efficient manner and to the cellulose microfibers produced thereby.

Description

Method for producing cellulose microfibers and cellulose microfibers produced thereby {METHOD FOR MANUFACTURING CELLULOSE MICROFIBER AND CELLULOSE MICROFIBER MANUFACTURED BY THE SAME}

The present invention relates to a method for producing cellulose microfibers and the cellulose microfibers produced thereby.

Petroleum-based synthetic polymers are widely used across industries due to their excellent strength properties and low price. However, petrochemical products not only emit carbon dioxide during the production process, but are also non-renewable resources and do not easily decompose in nature when discarded after use, causing serious environmental pollution. Therefore, biomass resources are attracting attention as a material that can solve or replace the disadvantages of using petrochemical products.

Among them, lignocellulosic biomass is a very abundant and renewable resource in nature and has been used for various purposes from the past to the present. Recently, cellulose, the main component of wood, has been manufactured into fine fibers such as cellulose nanofibrils (CNF) and microfibrillated cellulose (MFC). When used as an additive to sheets, films, or composite materials, these fine fibers not only improve mechanical strength but also have high biodegradability, so they are expected to be widely used as eco-friendly materials.

These are mainly high-purity cellulose such as kraft pulp and sulfite pulp derived from various types of wood, or lignin-cellulose complexes such as organic solvent pulp, dissolved in concentrated sulfuric acid or a special solvent, and then dispersed in water or milled. It is manufactured by grinding at low concentration for a long time using micronizing equipment such as a super mass colloider, high-pressure homogenizer, and micro fluidizer. However, these methods have the disadvantages of low yield, long processing time, and high energy consumption in manufacturing CNF or MFC.

Accordingly, for efficient production of CNF or MFC, a technology that can easily produce cellulose microfibers is needed.

The technical problem to be achieved by the present invention is to provide a method for producing cellulose microfibers in an economical and efficient manner and the cellulose microfibers produced thereby.

However, the problem to be solved by the present invention is not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

One embodiment of the present invention includes forming pulp by reacting biomass raw materials with a mixed solvent of a glycol ether-based solvent and an acid; mixing the pulp with a basic solution to prepare a pulp slurry; and introducing the pulp slurry into a mixer and kneading it to produce cellulose microfibers.

Additionally, an exemplary embodiment of the present invention provides cellulose microfibers manufactured by the above manufacturing method.

The method for producing cellulose microfibers according to an embodiment of the present invention can produce cellulose microfibers in an economical and efficient manner.

In addition, the method for producing cellulose microfibers according to an embodiment of the present invention is environmentally friendly compared to petrochemical products, and can easily produce cellulose microfibers with excellent strength.

In addition, cellulose microfibers according to an embodiment of the present invention can be used as a precursor for CNF or MFC to improve production efficiency, and can be easily applied as an additive or reinforcement for films, sheets, and composite materials.

However, the effects of the present invention are not limited to the effects described above, and may be expanded in various ways without departing from the spirit and scope of the present invention.

Figure 1 shows photographs taken using an optical microscope of cellulose microfibers prepared in Examples 1 to 3 of the present invention.

Throughout the specification of the present application, when a part is said to “include” a certain element, this means that it may further include other elements rather than excluding other elements, unless specifically stated to the contrary.

Throughout this specification, when a member is said to be located “on” another member, this includes not only the case where the member is in contact with the other member, but also the case where another member exists between the two members.

Hereinafter, the present invention will be described in more detail.

One embodiment of the present invention includes forming pulp by reacting biomass raw materials with a mixed solvent of a glycol ether-based solvent and an acid; mixing the pulp with a basic solution to prepare a pulp slurry; and introducing the pulp slurry into a mixer and kneading it to produce cellulose microfibers.

The method for producing cellulose microfibers according to an embodiment of the present invention can produce cellulose microfibers in an economical and efficient manner. In addition, the method for producing cellulose microfibers according to an embodiment of the present invention is environmentally friendly compared to petrochemical products, and can easily produce cellulose microfibers with excellent strength.

According to an exemplary embodiment of the present invention, the biomass raw material may include at least one of a lignocellulosic biomass raw material and a non-lignocellulosic biomass raw material. Specifically, the lignocellulosic biomass raw material may include at least one of coniferous wood chips and broadleaf wood chips, but the type of the lignocellulosic biomass raw material is not limited. In addition, the non-lignocellulosic biomass raw material may include at least one of kenaf, hemp, rice, bagasse, bamboo, seaweed, corn stalks, corn cores, rice straw, rice husk, wheat straw, and sugarcane stalks. However, the type of non-lignocellulosic biomass raw material is not limited. By using the above-described types of biomass raw materials, the cellulose microfibers, which are highly biodegradable and eco-friendly, can be manufactured.

According to one embodiment of the present invention, organic solvent pulp can be manufactured using the biomass raw material. Specifically, pulp can be formed by reacting biomass raw materials with a mixed solvent of a glycol ether-based solvent and an acid. When forming pulp by reacting biomass raw materials with a mixed solvent of glycol ether solvent and acid, the content of pulp contained in the pulp slurry and the amount of pulp slurry introduced into the mixer are adjusted during alkaline kneading, as described later. Thus, the physical properties of the produced cellulose microfibers can be easily adjusted. On the other hand, when using conventional kraft pulp, sulfurous acid pulp, etc., it may be difficult to easily control the physical properties of the produced cellulose microfibers even when controlling the conditions during alkaline kneading.

According to one embodiment of the present invention, the mixed solvent may be a mixture of a glycol ether-based solvent and an acid. The glycol ether-based solvent includes ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol methyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and It may include at least one of dipropylene glycol methyl ether. However, the type of glycol ether-based solvent is not limited. Additionally, hydrochloric acid, sulfuric acid, nitric acid, etc. may be used as the acid, but the type of acid is not limited.

According to one embodiment of the present invention, the mixed solvent may have a volume ratio of the glycol ether-based solvent and the acid of 95:5 to 99:1. Specifically, the volume ratio of the glycol ether-based solvent and the acid included in the mixed solvent may be 96:4 to 98.5:1.5, 96.5:3.5 to 98:2, or 97:3 to 97.5:2.5. When the volume ratio of the glycol ether-based solvent and the acid included in the mixed solvent is within the above-mentioned range, pulp can be effectively manufactured from the biomass raw material.

According to an exemplary embodiment of the present invention, in the step of forming the pulp, the mixed solvent may be reacted at a mixing ratio of 1L to 3L with respect to 1 Kg of the biomass raw material. Specifically, the mixing ratio of the mixed solvent for 1 Kg of the biomass raw material may be 1.5L to 2.5L, or 2L. By adjusting the mixing ratio of the biomass raw material and the mixed solvent to the above-mentioned range, the yield of the pulp produced can be improved.

According to one embodiment of the present invention, the step of forming the pulp may be performed at a temperature of 100 ℃ or more and 150 ℃ or less. Specifically, the temperature in the step of forming the pulp may be 110°C or higher and 140°C or lower, or 120°C or higher and 130°C or lower. By controlling the temperature at which the pulp forming step is performed within the above-described range, the pulp can be stably formed from the biomass raw material.

Additionally, the step of forming the pulp may be performed for a period of time between 60 minutes and 180 minutes, between 90 minutes and 160 minutes, or between 120 minutes and 150 minutes. When the time for performing the step of forming the pulp is within the above-mentioned range, the pulp can be stably formed and the yield of the pulp can be improved.

According to one embodiment of the present invention, the manufactured pulp can be washed. Specifically, lignin and the mixed solvent contained in the pulp can be removed using distilled water. Through this, impurities contained in the pulp can be minimized, and the alkaline kneading treatment described later can be effectively performed.

According to one embodiment of the present invention, a pulp slurry can be prepared by mixing the prepared pulp with a basic solution. The basic solution may include a sodium hydroxide solution, a potassium hydroxide solution, and a lithium hydroxide solution, but the type of the basic solution is not limited.

According to one embodiment of the present invention, the concentration of the basic solution included in the pulp slurry may be 0.1 N or more and 1 N or less. Specifically, the concentration of the basic solution may be 0.15 N or more and 0.8 N or less, 0.2 N or more and 0.6 N or less, or 0.25 N or more and 0.5 N or less. When the concentration of the basic solution is within the above-mentioned range, cellulose microfibers can be effectively formed from the pulp slurry.

According to one embodiment of the present invention, the pH of the pulp slurry may be 8 or more and 14 or less. Specifically, the pH of the pulp slurry may be 9 or more and 13 or less, or 10 or more and 12 or less. By adjusting the pH of the pulp slurry to the above-mentioned range, cellulose microfibers can be effectively formed from the pulp slurry. In addition, when the pH of the pulp slurry is within the above-mentioned range, swelling of the fibers included in the pulp slurry is promoted, and finer cellulose microfibers can be effectively manufactured through the kneading process described later.

According to an exemplary embodiment of the present invention, with respect to 100 parts by weight of the pulp slurry, the content of the pulp may be 3 parts by weight or more and 15 parts by weight or less. Specifically, with respect to 100 parts by weight of the pulp slurry, the pulp content is 4.5 parts by weight or more and 12.5 parts by weight or less, 5 parts by weight or more and 10 parts by weight or less, 3 parts by weight or more and 10 parts by weight or less, or 7.5 parts by weight or more. It may be less than one part by weight. For example, the content of the pulp included in the pulp slurry may be 3% by weight or more and 15% by weight or less.

By adjusting the content of the pulp included in the pulp slurry to the above-mentioned range, friction and dispersion between fibers are efficiently performed during the kneading process using a mixer, so that finely divided cellulose microfibers can be easily manufactured. On the other hand, if the content of the pulp contained in the pulp slurry is too small, the friction efficiency between fibers decreases, making it impossible to easily manufacture finely divided cellulose microfibers. Additionally, if the content of the pulp contained in the pulp slurry is too large, the pulp slurry has a high viscosity and there is a problem in that kneading is not performed smoothly.

Therefore, the method for producing cellulose microfibers according to an embodiment of the present invention can effectively produce micronized cellulose microfibers by adjusting the content of the pulp contained in the pulp slurry to the above-mentioned range, and the cellulose produced The physical properties of microfibers can be easily controlled.

According to one embodiment of the present invention, in the kneading step, the pulp slurry may be added in an amount of 5% to 95% of the total volume of the mixer. Specifically, the amount of the pulp slurry input is 5% to 95%, 6.5% to 90%, 8% to 75%, 8.5% to 60%, 10% to 50% of the total volume of the mixer. , 10% to 40%, 10% to 30%, 10% to 25%, 35% to 95%, 45% to 95%, 55% to 95%, 65% to 95%, It may be 75% or more and 95% or less, or 85% or more and 95% or less. For example, when the maximum capacity (total volume) of the mixer is 5,000 mL, the pulp slurry can be added to the mixer in a capacity of 250 mL or more and 4,750 mL or less.

When the amount of the pulp slurry added to the mixer is within the above-mentioned range, friction and dispersion between fibers are efficiently performed during the kneading process, so that finely divided cellulose microfibers can be easily manufactured. Meanwhile, by controlling the amount of the pulp slurry fed into the mixer, the physical properties of the produced cellulose microfibers, such as particle size, freeness, water retention, tensile index, and tear index, can be controlled in various ways. In particular, when the amount of the pulp slurry introduced in the kneading step is adjusted to 5% or more and 25% or less of the total volume of the mixer, physical properties such as particle size, freeness, water retention, tensile index, and tear index, which will be described later, Cellulose microfibers that satisfy can be effectively manufactured.

Therefore, the method for producing cellulose microfibers according to an embodiment of the present invention has the advantage of being able to control the physical properties of the produced cellulose microfibers in various ways by controlling the amount of the pulp slurry introduced into the mixer. Through this, it is possible to easily manufacture cellulose microfibers having the physical properties required in the field of application.

According to one embodiment of the present invention, the kneading step may be performed at a rotation speed of 100 rpm or more and 600 rpm or less. Specifically, the rotation speed at which the kneading step is performed may be 150 rpm or more and 550 rpm or less, 200 rpm or more and 500 rpm or less, 250 rpm or more and 450 rpm or less, or 300 rpm or more and 400 rpm or less. By adjusting the rotational speed at which the kneading step is performed within the above-mentioned range, the manufactured cellulose microfibers can be formed more stably. The rotation speed may refer to the rotation speed of the mixer used in the kneading step.

According to one embodiment of the present invention, the kneading step may be performed at a temperature of 20°C or more and 35°C or less. By adjusting the temperature of the kneading step to the above-mentioned range, deformation and damage of the produced cellulose microfibers can be prevented.

According to one embodiment of the present invention, the method for producing cellulose microfibers can control the physical properties of the cellulose microfibers to be produced by adjusting the time for performing the kneading. Specifically, the step of performing the kneading may be performed for 1 hour or more and 3 hours or less. Through this, it is possible to effectively manufacture cellulose microfibers that satisfy physical properties such as particle size, freeness, water retention, tensile index, and tear index, which will be described later. Meanwhile, the time for performing the kneading can be set according to the physical properties of the desired cellulose microfiber.

According to one embodiment of the present invention, the mixer into which the pulp slurry is added is a kneader and may be a Hobart mixer, a spiral mixer, or a vertical mixer. However, the type of mixer is not limited, and any known device capable of applying shear force to the pulp slurry can be used.

According to one embodiment of the present invention, the method for producing cellulose microfibers may further include the step of eluting lignin contained in the cellulose microfibers using a basic solution. Specifically, after mixing the cellulose microfibers prepared through the alkaline kneading process with the basic solution, filtration and dehydration may be performed to elute the lignin contained in the cellulose microfibers. Thereafter, in order to remove the basic solution contained in the cellulose microfibers, they can be washed with distilled water until they become neutral. The basic solution used in the step of eluting the lignin may be the same as the basic solution used when preparing the pulp slurry.

According to one embodiment of the present invention, the lignin content of the cellulose microfibers may be 0.1% by weight or more and 30% by weight or less. Specifically, the lignin content of the cellulose microfibers may be 1% by weight to 28% by weight, 5% to 25% by weight, 10% to 22.5% by weight, or 15% to 20% by weight. Even when the lignin content remaining in the manufactured cellulose microfiber is within the above-mentioned range, by performing the alkaline kneading process, the physical properties such as freeness, water retention, tensile index, and tear index of the manufactured cellulose microfiber are easy. can be controlled properly.

According to one embodiment of the present invention, the method for producing cellulose microfibers may further include the step of refining the produced cellulose microfibers. By refining the cellulose microfibers, cellulose nanofibrils (CNF) or microfibrillated cellulose (MFC) can be manufactured. In order to refine the cellulose microfibers, a high-pressure homogenizer, a high-pressure emulsifier, etc. used in the art can be used.

One embodiment of the present invention provides cellulose microfibers manufactured by the above manufacturing method.

Cellulose microfibers according to an embodiment of the present invention can be used as a precursor for CNF or MFC to improve production efficiency, and can be easily applied as an additive or reinforcement for films, sheets, and composite materials.

According to one embodiment of the present invention, the cellulose microfibers may exist in the form of single fibers or microfibrils composed of one fiber, or may exist in the form of microfibers entangled with each other.

According to one embodiment of the present invention, the size of the cellulose microfibers may be 0.1 ㎛ or more and 500 ㎛ or less. Specifically, the size of the cellulose microfibers is 1 ㎛ to 475 ㎛, 5 ㎛ to 450 ㎛, 10 ㎛ to 400 ㎛, 20 ㎛ to 375 ㎛, 30 ㎛ to 350 ㎛, 40 ㎛ to 320 ㎛. Hereinafter, 0.1 ㎛ or more and 200 ㎛ or less, 7.5 ㎛ or more and 195 ㎛ or less, 15 ㎛ or more and 180 ㎛ or less, 20 ㎛ or more and 150 ㎛ or less, 35 ㎛ or more and 140 ㎛ or less, 200 ㎛ or more and 500 ㎛ or less, 225 ㎛ or more. 450 ㎛ or less , it may be 250 ㎛ or more and 400 ㎛ or less, or 270 ㎛ or more and 380 ㎛ or less. That is, through the method for producing cellulose microfibers, cellulose microfibers having the above-described size can be effectively produced.

According to one embodiment of the present invention, the length ratio of the cellulose microfibers may be 25 or more and 100 or less. Specifically, the length ratio of the cellulose microfibers may be 27.5 or more and 85 or less, 30 or more and 70 or less, or 30 or more and 65 or less. That is, through the method for producing cellulose microfibers, cellulose microfibers having the above-described length-to-width ratio can be effectively produced. In addition, the cellulose microfibers whose length-to-width ratio satisfies the above-mentioned range can have excellent strength characteristics.

According to one embodiment of the present invention, the cellulose microfibers may have a freeness (CSF) of 30 mL or more and 600 mL or less. Specifically, the freeness of the cellulose microfiber is 50 mL to 580 mL, 100 mL to 550 mL, 150 mL to 550 mL, 200 mL to 550 mL, 100 mL to 250 mL, or 30 mL or more. It may be less than 200 mL. In other words, cellulose microfibers having the above-mentioned freeness can be effectively manufactured through the above-described cellulose microfiber manufacturing method.

According to one embodiment of the present invention, the water retention value (WRV) of the cellulose microfibers may be 150% or more and 1,000% or less. Specifically, the water retention degree of the cellulose microfiber may be 160% or more and 900% or less, 180% or more and 800% or less, 190% or more and 700% or less, or 200% or more and 600% or less. That is, through the above-mentioned cellulose microfiber production method, cellulose microfibers having the above-mentioned water retention degree can be effectively produced.

According to one embodiment of the present invention, a microfiber film and a microfiber sheet can be manufactured using the cellulose microfibers. Additionally, the cellulose microfibers can be used as reinforcing agents, additives, etc. in composite materials.

Additionally, the cellulose microfibers can be used as a raw material for manufacturing cellulose nanofibrils (CNF), microfibrillated cellulose (MFC), etc. Specifically, CNF or MFC can be manufactured by micronizing the cellulose microfibers. Additionally, a film or sheet can be manufactured using CNF or MFC produced by micronizing the cellulose microfibers.

Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention may be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those skilled in the art.

Example 1

Manufacturing of cellulose microfibers

Softwood wood chips were prepared. The prepared coniferous wood chips have a clason lignin content of about 28.7%, and the size of the chips is 35 (±3) mm high x 8 (±3) mm wide x 7 (±2) mm thick.

Afterwards, ethylene glycol monomethyl ether as a glycol ether solvent and sulfuric acid (95%) as an acid were prepared, and ethylene glycol monomethyl ether and sulfuric acid were mixed in a volume ratio of 97:3 to prepare a mixed solvent.

Afterwards, 1 kg of wood chips were put into a high-pressure steam treatment device (autoclave, HST 506-6, Hanbaek ST, Korea) at a mixing ratio of 2 L of mixed solvent, reacted at 120°C for 120 minutes, filtered with distilled water, and 680 mL of free water was added. Organic solvent pulp (lignin content 27.4%) containing (CSF) was prepared.

Pulp slurry was prepared by mixing the prepared organic solvent pulp with 0.25 N NaOH aqueous solution (500 mL). At this time, the content of organic solvent pulp was 5 parts by weight (5.0% by weight) based on 100 parts by weight of the pulp slurry, and the pH of the pulp slurry was about 13.

Afterwards, about 499.5 mL (about 11.1% of the total volume of the mixer) of the pulp slurry was added to a Hobart mixer with a maximum capacity (total volume) of 4,500 mL, and kneaded for 1 hour at a rotation speed of 281 rpm to produce cellulose microfibers. was obtained. Afterwards, 2,000 mL of 0.5 N NaOH aqueous solution was added to the obtained cellulose microfibers, followed by filtration and dehydration to elute lignin. The water washing process was repeated to remove the remaining NaOH component to finally prepare cellulose microfibers.

Meanwhile, the kneading treatment time was set to 2 hours and 3 hours, and cellulose microfibers were additionally manufactured in the same manner as above.

Manufacturing of microfiber films

The cellulose microfibers prepared above were diluted with distilled water to have a solid content of 0.2% by weight, then formed into a paper web using a reduced pressure and filtration method, and dried in a gel dryer at 80° C. to prepare a microfiber film.

Example 2

In Example 1, cellulose microfibers and microfiber films were prepared in the same manner as in Example 1, except that the content of organic solvent pulp was adjusted to 7.5 parts by weight (7.5% by weight) based on 100 parts by weight of pulp slurry. Manufactured.

Example 3

In Example 1, cellulose microfibers and microfiber films were prepared in the same manner as in Example 1, except that the content of organic solvent pulp was adjusted to 10 parts by weight (10% by weight) based on 100 parts by weight of pulp slurry. Manufactured.

Example 4

In Example 2, cellulose was prepared in the same manner as in Example 2, except that about 999 mL (about 22.2% of the total volume of the mixer) of pulp slurry was added to a Hobart mixer with a maximum capacity (total volume) of 4,500 mL. Microfibers and microfiber films were manufactured.

Example 5

Cellulose microfibers prepared in Example 1 were prepared by performing alkaline kneading for 1 hour. Afterwards, MFC was prepared by passing the cellulose microfibers three times through a high-pressure homogenizer (Panda plus2000, GEA Niro Soavi., Italy) with a pressure of 1,000 bar.

Afterwards, the prepared MFC was diluted with distilled water to have a solid content of 0.2% by weight, then paper was formed by reduced pressure and filtration, and dried in a gel dryer at 80°C to prepare an MFC film.

Example 6

Cellulose microfibers prepared in Example 1 were prepared by performing alkaline kneading for 1 hour. Afterwards, MFC was prepared by passing the cellulose microfibers three times through a high-pressure emulsifier (NLM100 (ISA-NLM100), Ilshin autoclave, Korea) with a pressure of 1,000 bar.

Afterwards, the prepared MFC was diluted with distilled water to have a solid content of 0.2% by weight, then paper was formed by reduced pressure and filtration, and dried in a gel dryer at 80°C to prepare an MFC film.

Reference example 1

Bleached hardwood kraft pulp (HwBKP) was pretreated with endo-glucanase, a cellulose-degrading enzyme, and then passed through a high-pressure homogenizer (Ariete NS311OH, GEA Niro Soavi, Italy) seven times at a pressure of about 900 bar to prepare CNF.

Afterwards, the prepared CNF was diluted with distilled water to have a solid content of 0.2% by weight, then paper was formed by reduced pressure and filtration, and dried in a gel dryer at 80°C to prepare a CNF film.

Comparative Example 1

The organic solvent pulp prepared in Example 1 was prepared. Afterwards, MFC was prepared by passing the organic solvent pulp three times through a high-pressure homogenizer (Panda plus2000, GEA Niro Soavi., Italy) with a pressure of 1,000 bar.

Afterwards, the prepared MFC was diluted with distilled water to have a solid content of 0.2% by weight, then paper was formed by reduced pressure and filtration, and dried in a gel dryer at 80°C to prepare an MFC film.

Experiment example

Measurement of residual lignin content

The remaining lignin content of the cellulose microfibers prepared in Example 1 was measured as follows.

Specifically, a sample was prepared by freeze-drying the cellulose microfiber prepared in Example 1, and 5 mL of 72% concentration sulfuric acid was added to 0.2 g of the dry cellulose microfiber sample, and stirred every hour for 4 hours. It was left to stand at room temperature. Afterwards, it was diluted by adding 196 mL of distilled water, and then reacted in an autoclave at 120°C for 2 hours. After the reaction was completed, pressure was filtered through a glass filter using distilled water, and the residue on the glass filter was dried in a dryer at 105°C. Afterwards, the remaining lignin content was calculated using Equation 1 below.

[Equation 1]

L = W/S

In Equation 1 above, “L” is the residual lignin content, “S” is the dry weight of the sample (g), and “W” is the weight of the dried residue (g).

Additionally, the remaining lignin content of the cellulose microfibers prepared in Examples 2 to 4 was measured and shown in Table 1 below.

Measurement of particle size and aspect ratio

The particle size and length ratio of the cellulose microfibers prepared in Example 1 were measured as follows.

Specifically, the particle size of the cellulose microfibers prepared in Example 1 was analyzed using a particle size analyzer (Mastersizer 3000, Alvern Instruments Ltd., Orcestershire, UK). In addition, photos of cellulose microfibers taken at 60x magnification using an optical microscope (BX 50, Olympus Otical Co. Ltd., Japan) were analyzed using an image analysis program (IMT I-Solution Inc., Canada) to determine 100 fiber lengths and The fiber width was measured, and the length-to-width ratio was calculated from this.

In addition, the particle size and length ratio of the cellulose microfibers prepared in Examples 2 to 4 were measured and shown in Table 2 below.

Measurement of freeness and conservatism

The freeness (CSF) and water retention (WRV) of the cellulose microfibers prepared in Example 1 were measured as follows.

Specifically, the freeness of 1L of slurry containing 0.3% by weight of cellulose microfibers was measured using a Canadian standard freeness meter. The water temperature of the slurry was 20°C, and the unit of freeness (CSF) was mL.

Additionally, the water retention value (WRV) of the cellulose microfibers prepared in Example 1 was analyzed according to TAPPI UM 256. Specifically, after quantifying 10 mL of slurry containing 5% by weight of cellulose microfibers, a glass filter (1G4) was installed in a 50 mL conical tube and centrifuged at 1800 G for 20 minutes in a centrifuge (1580, Gyrozen, Korea). Treated and dried in a dryer at 105°C for 12 hours. The total weight of cellulose microfibers was measured and WRV was calculated according to Equation 2 below.

[Equation 2]

In Equation 2, “W _Wet ” is the wet weight of the cellulose microfibers, and “W _dry ” is the dry weight of the cellulose microfibers.

Additionally, the freeness and water retention of the cellulose microfibers prepared in Examples 2 to 4 were measured and shown in Table 3 below.

Tensile index measurement

The tensile index of the microfiber film prepared in Example 1 was measured as follows.

A sample was prepared by cutting the microfiber film prepared in Example 1 into 5 cm in width and 1 cm in height, and the tensile index of the sample was measured using a tensile tester (OTT-005, Oriental TM, Korea) based on ASTM D 822. Measured. At this time, the load cell load of the measuring device was 50 N, the tensile speed was 10 mm/min, and the distance between the measuring devices was fixed at 3 cm.

In addition, the tensile index of the microfiber films prepared in Examples 2 to 4 was measured and shown in Table 4 below.

In addition, the tensile index was measured for the MFC film prepared in Example 5, Example 6, and Comparative Example 1 and the CNF film prepared in Reference Example 1 in the same manner as above, and the results are shown in Table 5 below.

Tear index measurement

The tear index of the microfiber film prepared in Example 1 was measured as follows.

Samples were prepared by cutting the microfiber film prepared in Example 1 into 5 cm wide and 6 cm long based on TAPPI T 414, and using an Elmendorf tearing tester (DM-805, Taeil, Korea). The tear index of the microfiber film was measured.

Additionally, the tear index of the microfiber films prepared in Examples 2 to 4 was measured and shown in Table 4 below.

transference number(%) Residual lignin content (%) Kneading time Example 1 Example 2 Example 3 Example 4 Example 1 Example 2 Example 3 Example 4 1 hours 93.7 91.2 91.2 90.1 18.1±0.6 17.8±0.8 18.2±0.6 18.1±0.3 2 hours 92.4 91.4 90.4 89.8 18.3±0.2 18.0±0.7 17.7±0.2 17.5±0.7 3 hours 91.8 90.1 88.4 88.2 18.4±0.9 17.6±0.1 17.3±0.9 17.3±0.1

Particle size (㎛) long rain Kneading time Example 1 Example 2 Example 3 Example 4 Example 1 Example 2 Example 3 Example 4 1 hours 301.4 250.1 190.7 120.7 44.3 33.4 36.6 50.1 2 hours 288.1 301.4 124.4 97.4 40.2 38.3 31.8 55.4 3 hours 274.4 199.4 67.9 48.7 39.6 32.6 30.7 60.7

Yeosudo (mL) Conservative (%) Kneading time Example 1 Example 2 Example 3 Example 4 Example 1 Example 2 Example 3 Example 4 1 hours 520±8 237±5 187±9 180±11 208.8±5.0 240.5±7.3 249.1±5.9 251.7±4.7 2 hours 350±29 213±5 93±9 90±8 225.2±5.4 251.4±5.0 300.3±3.1 310.4±3.6 3 hours 247±12 117±12 43±5 41±7 229.7±2.0 322.0±4.7 447.0±4.5 509.4±1.2

Tensile index (N·m/g) Tear index (mN·m ² /g) Example 1 37.1±2.2 0.142±0.005 Example 2 40.0±6.1 0.115±0.015 Example 3 51.9±3.3 0.096±0.038 Example 4 56.2±4.9 0.089±0.022

Tensile index (N·m/g) Example 5 102.3±8.8 Example 6 87.4±17.3 Reference example 1 100.6±12.9 Comparative Example 1 23.7±7.6

Figure 1 shows photographs taken using an optical microscope of cellulose microfibers prepared in Examples 1 to 3 of the present invention.

Referring to Figure 1, it can be seen that the size and shape of the produced cellulose microfibers vary depending on the content of organic solvent pulp contained in the pulp slurry and the time for performing alkaline kneading.

Referring to Tables 1 to 5, the method for producing cellulose microfibers according to an exemplary embodiment of the present invention includes the following factors: kneading time for the pulp slurry, content of organic solvent pulp contained in the pulp slurry, and pulp filled in the mixer. It can be seen that by controlling the amount of slurry, physical properties such as particle size, length ratio, freeness, and water retention of the produced cellulose microfibers and the tensile index and tear index of the microfiber film can be easily controlled.

The foregoing detailed description illustrates and explains the invention. In addition, the foregoing merely shows and describes preferred embodiments of the present invention, and as described above, the present invention can be used in various other combinations, modifications, and environments, and the scope and scope of the inventive concept disclosed in this specification. Changes or modifications may be made within the scope of equivalent disclosure and/or skill or knowledge in the art. Accordingly, the above detailed description of the invention is not intended to limit the invention to the disclosed embodiments. Additionally, the appended claims should be construed to include other embodiments as well.

Claims (14)

forming pulp by reacting biomass raw materials with a mixed solvent of a glycol ether-based solvent and an acid;
Preparing a pulp slurry by mixing 3 to 15 parts by weight of the pulp with a basic solution based on 100 parts by weight of the pulp slurry; and
Injecting the pulp slurry into a mixer in an amount of 8.5% to 60% of the total volume of the mixer and kneading for 1 to 3 hours to produce cellulose microfibers; and
A method of producing cellulose microfibers comprising: eluting lignin contained in the cellulose microfibers using a basic solution.
According to paragraph 1,
A method of producing cellulose microfibers, wherein the biomass raw material includes at least one of a lignocellulosic biomass raw material and a non-lignocellulosic biomass raw material.
According to paragraph 1,
A method for producing cellulose microfibers, wherein the mixed solvent is reacted at a mixing ratio of 1L to 3L with respect to 1 Kg of the biomass raw material.
According to paragraph 1,
A method of producing cellulose microfibers, wherein the step of forming the pulp is performed at a temperature of 100 ℃ or more and 150 ℃ or less.
delete According to paragraph 1,
A method for producing cellulose microfibers, wherein the concentration of the basic solution contained in the pulp slurry is 0.1 N or more and 1 N or less.
According to paragraph 1,
A method for producing cellulose microfibers, wherein the pH of the pulp slurry is 8 or more and 14 or less.
delete delete Cellulose microfibers manufactured by the manufacturing method according to claim 1.
According to clause 10,
Cellulose microfibers wherein the size of the cellulose microfibers is 0.1 ㎛ or more and 500 ㎛ or less.
According to clause 10,
Cellulose microfibers wherein the length ratio of the cellulose microfibers is 25 or more and 100 or less.
According to clause 10,
The cellulose microfiber is a cellulose microfiber having a freeness (CSF) of 30 mL or more and 600 mL or less.
According to clause 10,
Cellulose microfibers wherein the water retention value (WRV) of the cellulose microfibers is 150% or more and 1,000% or less.