KR20200011071A - A Method for Manufacturing of High Strength Nanocellulose Longfiber by using Steam Treatment and Extrusion - Google Patents

Abstract

The present invention is capable of providing a high-strength nanocellulose long fiber by the steam treatment on a nanocellulose ointment material which is formed by mixing nanocellulose powder and ultra-pure water, so as to obtain an effect of increasing a covalent bond between nanocellulose due to saturated steam and a constant pressure and temperature. Thus, the high-strength nanocellulose long fiber has the extrusion stability such that the nanocellulose is homogeneously dissolved and coupled to the extruded long fiber without adding a separate chemical substance.

Description

A method for manufacturing of high strength nanocellulose longfiber by using steam treatment and extrusion}

The present invention relates to a method for producing high strength nanocellulose long fibers using steam treatment and extrusion molding, and more particularly, after supplying an ointment mixture containing ultrapure water mixed with nanocellulose to a steam chamber, a constant pressure and temperature The present invention relates to a method for producing a high strength nanocellulose long fiber by injecting extruded homogeneously aged and swelled nanocellulose ointment mixture in a chamber by adding saturated steam at a predetermined time in an extruder maintained at a constant temperature.

Recently, the demand for fiber-reinforced composites using environmentally friendly materials is increasing, and the method of producing environmentally friendly high strength fibers to determine the mechanical properties of the composites is very important. Eco-friendly high-strength fiber is used as an eco-friendly structural composite material because it strengthens the mechanical characteristics of the composite material and has almost no environmental pollution.

Renewable, biodegradable and thermally stable cellulose has many advantages such as low cost and low load. Recently, chemicals, coatings, fabrics, laminated materials, sensors, actuators, flexible electronics, flexible displays have a wide range of influences, such as a wide range of interest has received great attention. Cellulose fibers consist of cellulose nanocrystals (CNCs) and nanocelluloses called cellulose nanofibers (CNF). Nanocelluloses generally have a width of 5 to 100 nm and a length of several um. The elastic modulus of the nanocellulose has a high mechanical property of about 150 GPa in the longitudinal direction and about 18 to 50 GPa in the vertical direction.

Conventionally, various attempts have been made for the production of homogeneous high-strength cellulose long fibers by adding chemicals or removing impurities through filtering. However, the physical properties of the fibers are degraded due to undissolved cellulose, and the filter is replaced to remove impurities. It has several limitations such as cost increase due to frequency, complicated manufacturing process and low extrusion stability.

Therefore, there is a need for the development of nanocellulose long fibers that are homogeneous and have improved strength without using complicated processes and separate chemicals.

As a technique related to cellulose, Korean Patent No. 1767286 discloses a cellulose dispersion liquid capable of controlling the particle size peak of fine cellulose obtained even by applying mechanical treatment to oxidized cellulose, and sufficient flexibility and gas barrier properties formed using the same. The molded article which has is described. The volume-based particle size distribution of the micro-oxidized cellulose in the cellulose dispersion containing at least micro-oxidized cellulose is in the range of the volume-based particle size of 0.01 µm or more and 100 µm or less, and has a particle size peak of 2 or more. Moreover, a molded object is formed using such a cellulose dispersion liquid.

Korean Patent No. 0149282 relates to a method for producing cellulose fibers characterized by spinning a cellulose solution using an organic solvent by a wet and dry spinning method, and more specifically, to a high-grade cellulose component obtained from wood pulp, Manufacturing method of spinning molding cellulose fibers by using a cellulose solution prepared by dissolving a mixture of N-methylmorpholine N-oxide (hereinafter referred to as “NMMO”) which is an amine oxide as a non-solvent as a spinning solution It describes.

Korean Patent No. 0486811 relates to a method for producing cellulose fibers prepared from a homogeneous cellulose solution even at low temperature. After dissolving a small amount of cellulose powder in a liquid concentrated N-methylmorpholine N-oxide (NMMO), the solution and cellulose The powder is fed to an extruder, mixed, swelled, and dissolved in an extruder to produce a homogeneous cellulose solution at low temperature, which is then extruded and spun through a spinning nozzle, and then passed through an air layer to reach a coagulation bath. It relates to a method for producing a cellulose fiber comprising the step of winding by drying and emulsion treatment.

This can supply the NMMO solution to the extruder at a relatively low temperature due to the effect of dissolving a small amount of pulp in the liquid concentrated NMMO to lower the melting point of the NMMO. Due to the above-described reasons, not only a wide process temperature range is possible, but also swelling of cellulose powder and NMMO solution at low temperature can be prevented from forming film on the surface of cellulose powder by instant dissolution by high temperature NMMO. It is possible to produce a homogeneous cellulose solution even at low temperature, and also to suppress cellulose decomposition generated during the high temperature swelling dissolution process in the extruder, thereby providing cellulose fibers with excellent flexibility and strength.

Korean Patent Publication No. 10-1767286 Domestic Publication No. 10-0149282 Domestic Publication No. 10-0486811

The present invention is to solve the problems of the prior art as described above, by steam treatment in the ointment material mixed with nanocellulose and ultrapure water, the effect of increasing the covalent bond between the nanocellulose due to the saturated steam and a certain pressure and temperature Due to this, an object of the present invention is to provide a manufacturing method capable of extruding high-strength nanocellulose long fibers having extrusion stability such that nanocellulose is uniformly dissolved and bonded to the extruded long fibers without adding a separate chemical. It is done.

In order to achieve the above object, the present invention homogeneously mixes nanocellulose with ultrapure water to produce a nanocellulose ointment phase of a certain concentration. Raw materials of nanocellulose include conifers, hardwoods, cotton, herbaceous plants, bamboo, bacterial cellulose and red algae.

The present invention supplies a nano-cellulose ointment material having a certain concentration prepared by the above method into a steam chamber capable of applying a constant temperature and saturated steam pressure, and then applying a saturated steam pressure and temperature for a predetermined time, and then It provides a manufacturing method comprising the step of injecting into a temperature-maintaining extruder and extruding high strength nanocellulose long fibers through an extrusion nozzle.

According to the present invention, it is possible to prepare nanocellulose long fibers having excellent flexibility and strength as well as homogeneous and extrusion stability using steam pressure without adding a separate chemical. In addition, the high-strength nanocellulose filament according to the present invention is light in weight to produce a low weight high strength composite material.

1 is a process schematic diagram for producing a high strength nanocellulose long fiber of the present invention,
2 is a SEM result of the nanocellulose long fiber,
3 is a graph showing tensile test results of nanocellulose long fibers prepared by performing a steam pressure process and nanocellulose long fibers prepared without performing a steam pressure process, and
Figure 4 is a graph of FTIR comparison results of nanocellulose long fibers prepared by performing the steam pressure process and nanocellulose long fibers prepared without performing the steam pressure process.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The present invention,

(A) dissolving and mixing nanocellulose in ultrapure water to produce a nanocellulose ointment phase of a certain concentration;

(B) supplying the nanocellulose ointment phase having a predetermined concentration with ultrapure water to a vapor pressure chamber to add co-saturated nanocellulose by adding ultrapure steam saturated at a predetermined time and temperature in the chamber to the nanocellulose ointment;

(C) characterized in that it comprises the step of supplying the nanocellulose ointment mixture to an extruder maintained at a constant temperature, extrusion spinning through an extrusion nozzle having a variety of diameters, followed by drying at room temperature to obtain nanocellulose long fibers.

In addition, the size of the nanocellulose administered in the step (A) is 5 ~ 200 nm in diameter, the length is preferably a size of several nm ~ several um.

In addition, the concentration of the nanocellulose ointment prepared in step (A) is preferably 2 to 50% by weight.

In addition, the temperature in the chamber in the step (B) is preferably maintained at a temperature of 100 to 150 ℃.

In addition, the pressure in the chamber in the step (B) is preferably maintained at 1 to 3 atm.

In addition, in the step (B), the time for applying the vapor pressure to the nanocellulose ointment is preferably 20 minutes to 5 hours.

In addition, the extruder in the step (C) is preferably maintained at 80 to 160 ℃ is supplied a nanocellulose ointment phase.

In addition, the diameter of the extrusion nozzle used in the step (C) is preferably 30 um to 500 um.

In addition, the nanocellulose powder in step (A) may be used by mixing with a crosslinking agent such as polyvinyl alcohol.

Figure 1 is a schematic view of the process of the present invention to prepare a nanocellulose ointment material and supply it to the steam pressure chamber to give a steam pressure for a certain time, and then schematically shows a process sequence for producing long fibers.

The nanocellulose powder used in FIG. 1 is cellulose nanocrystals (CNC) or cellulose nanofibers (CNF).

When cellulose nanocrystals and ultrapure water are mixed, they are mixed using a mixer for uniform mixing to produce nanocellulose ointment materials. In this case, if the cellulose nanocrystal masses aggregated in the eye are not mixed for a sufficient time and exist in the nanocellulose ointment phase, the long fibers extruded through the steps (B) and (C) may be defective.

In addition, if the nanocellulose concentration of the prepared nanocellulose ointment material is less than 2% by weight, the content of nanocellulose in the ointment is too low, the strength of the long fiber may be reduced, if the concentration of the ointment phase exceeds 50% by weight nano The solubility of cellulose may be inferior, and viscosity is too high and extrusion stability falls.

The nanocellulose ointment material is supplied to the vapor pressure chamber with ultrapure water and maintained for 20 minutes to 5 hours at a temperature of 100 to 150 ° C. and a pressure of 1 to 3 atmospheres. Applying the saturated steam and a certain temperature to the nanocellulose ointment material for a certain time may increase the covalent bond between the nanocellulose through the steam, which helps to strengthen the long fiber. In addition, it dissolves the insoluble nanocellulose and adds the effect of swelling to form a homogeneous nanocellulose ointment phase.

The prepared nanocellulose ointment material is fed to an extruder. The extruder is equipped with a temperature-controlled heater, and is equipped with a nozzle adapter that can be extruded by replacing extrusion nozzles of various diameters. At this time, the temperature of the extruder is preferably maintained at a temperature of 80 to 160 ℃.

Example 1

The powdered cellulose nanocrystals were mixed homogeneously with ultrapure water using a mixer to prepare nanocellulose ointment materials. At this time, the prepared cellulose ointment phase was prepared at a concentration of 35% by weight.

The nanocellulose ointment material was supplied to the vapor pressure chamber to stay at 120 ° C. and 2 atm for 3 hours to promote covalent bonds between the cellulose nanocrystals due to the vapor pressure. The mixture was allowed to mix homogeneously and swell. The concentration of the ointment of the nanocellulose ointment was about 32.7% by weight, and was in a homogeneous state without ultrapure water and insoluble cellulose nanocrystal particles.

The nanocellulose ointment phase subjected to the vapor pressure step is fed to an extruder and extruded into nanocellulose long fibers. At this time, the extruder was maintained at 160 ℃, the extrusion nozzle was used having a diameter of 340, 360, 180, 100um. The extruded nanocellulose long fibers are dried at room temperature in the air layer.

The diameter of the extruded long fibers decreases as the diameter of the extrusion nozzle decreases as shown in FIG. 2.

Comparative Example 1

In order to compare the characteristics of the long fiber and the long fiber that was not subjected to the steaming process, the nanocellulose long fiber was prepared by performing only steps (A) and (C) except step (B). And the used extrusion nozzle used the nozzle of 100um diameter.

As shown in FIG. 3, the Young's modulus is 4.03 GPa for the long fibers subjected to the steam pressure process extruded from 100 um diameter. And in the case of the long fiber prepared through Comparative Example 1, not subjected to the steam pressure process, the Young's modulus is 2.85 GPa. This shows that the Young's modulus of the long fibers produced through the steaming process is further increased.

In addition, the FTIR comparison results of the long fiber and the long fiber that did not perform the steam treatment process is shown in FIG. As a result, in the long fiber graph without the steam treatment, the peak of 1028 cm ^-1 , which is the position of the COC covalent bond, did not appear. 1028 cm ^-1 peak appeared. This means that when the steam pressure process is performed, covalent bonds between the nanocellulose in the long fibers are increased.

Claims (9)

(A) preparing an ointment material comprising 2 to 50% by weight of nanocellulose prepared by mixing ultrapure water with the powdered nanocellulose;
(B) supplying the nanocellulose ointment material with ultrapure water to the vapor pressure chamber to add ultrapure water saturated at a certain time and temperature to the nanocellulose ointment material in the chamber; And
(C) supplying the nanocellulose ointment material to an extruder maintained at a constant temperature, extrusion spinning through an extrusion nozzle having a variety of diameters, and then reaching the air layer and drying at room temperature to produce nanocellulose long fibers Method for producing nanocellulose long fibers ..
The method of claim 1,
The powdered nanocellulose of step (A) includes powdered cellulose nanofibers (Cellulose Nanofiber, CNF) or powdered cellulose nanocrystals (Cellulose Nanocrystal, CNC), the powdered nanocellulose diameter is 5 To 200 nm, the length of the nanocellulose long fiber having a number of nm to several um.
The method of claim 1,
The temperature in the chamber in the vapor pressure chamber of the step (B) is 100 to 150 ℃ temperature manufacturing method of nanocellulose long fibers.
The method of claim 1,
The pressure in the vapor pressure chamber of the step (B) is a method for producing nanocellulose long fibers of 1 to 3 atm.
The method of claim 1,
The method for producing nanocellulose long fibers in the steam pressure chamber of step (B) is 20 minutes to 5 hours.
The method of claim 1,
The extruder in the step (C) is maintained at 80 to 160 ℃ manufacturing method of nanocellulose long fibers for supplying nanocellulose ointment material.
The method of claim 1,
The diameter of the extrusion nozzle used in the step (C) is 30 um to 500 um method of producing a nanocellulose long fiber.
The method of claim 1,
In the step (A), the nanocellulose powder is used for mixing with the crosslinking agent polymer material.
A long fiber reinforced high strength composite prepared according to the method of any one of claims 1 to 8.

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