KR100593702B1 - Cellulose-based natural fibers having a porous structure and a method of manufacturing the same - Google Patents

Abstract

The present invention relates to a cellulose-based natural fiber having a porous structure and a method of manufacturing the same, the main object of which is to irradiate the surface of the cellulose-based natural fiber with an electron beam while maintaining a porous structure in the cellulose-based natural fiber at the same time cellulose-based natural fiber The present invention provides a cellulose-based natural fiber treatment method for removing impurities from a surface and providing functional groups, and a cellulose-based natural fiber treated by such a method.

This effect according to the present invention is not only serves as a reinforcement when the porous cellulose-based natural fiber is used as a reinforcement of the polymer composite material for interior and exterior materials of the automobile or building industry, but also an additional role such as shock absorption or noise prevention by the porous structure. You can also expect. In addition, the method for treating cellulose-based natural fibers according to the present invention is an environmentally friendly method that can save energy and emit no chemical pollutants as a dry method as compared to an alkaline solution processing method which is generally used. In addition, the cellulose-based natural fiber treatment method according to the present invention is added by adding only functional groups to the surface, controlling the internal pore size, or degenerate the cellulose structure itself of the cellulose-based natural fiber by controlling the irradiation intensity of the high energy beam There is an advantage to obtain environmentally friendly characteristics.

Cellulose-based natural fiber, high energy beam irradiation, functional group, pore size, porous structure

Description

Cellulose-based natural fiber having a porous structure and a manufacturing method thereof {Cellulosic Natural Fiber with Porous Inside and Its Method}

1 is a comparison of the cellulose-based natural fiber manufacturing method according to the present invention and the conventional chemical method,

Figure 2a, b is a cellulose-based natural fiber surface and cross-sectional structure (SEM photograph) treated according to the present invention,

Figure 3a, b is a cellulose-based natural fiber surface and cross-sectional structure diagram (SEM photograph) treated by a conventional chemical method,

4 is a graph showing the degree of polymerization of the cellulose-based natural fibers changed according to the irradiation beam intensity,

5 is a graph showing the viscosity change characteristics of the cellulose-based natural fibers changed according to the irradiation beam intensity.

The present invention relates to a cellulose-based natural fiber having a porous structure and a method of manufacturing the same, and in particular, to remove the impurities attached to the surface of the cellulose-based natural fiber and impart functional groups to the surface and at the same time to provide a porous structure inside the cellulose-based natural fiber It is about forming.

Cellulose-based natural fiber treatment method, which has been generally used up to now, is a chemical treatment method using alkaline solution. After immersing cellulose-based natural fiber in NaOH aqueous solution (2 wt%, 5 wt%, 10 wt%) for 1 hour, Neutralize in 2wt% acetic acid solution, and then wash the cellulose-based natural fiber with distilled water.

Cellulose-based natural fibers completely removed from the alkaline and acidic components are dried in air for several days, and then placed in a dryer maintained at 105 ° C to 110 ° C to be dried for at least 1 hour to completely remove moisture in the cellulose-based fiber. Can be used as

However, the cellulose-based natural fiber prepared by the above chemical treatment method removes impurities on the surface and forms functional groups, but the cellulose structure of the fiber swells while the cellulose-based natural fiber is contained in an alkaline solution and then shrinks during drying. As a result, it is impossible to form a porous structure therein. In addition, there is a problem that there is a fear that the fiber is damaged when treated with a strong alkaline solution. For reference, Figure 3a, b is a surface of the cellulose-based natural fibers and cross-sectional structure (SEM picture) treated by the conventional chemical method, cellulose-based natural fibers (fiber treated for 1 hour in 5% NaOH aqueous solution) In the surface (X500) and the cross section (X1000) of the same problem as described above.

An object of the present invention for solving the above problems is to environmentally friendly and energy-saving to form a porous structure in the interior of the fiber while at the same time at the same time to remove impurities and impart functional groups on the surface of the cellulose-based natural fiber by irradiating a high energy beam It is to provide a cellulose-based natural fibers and a method of manufacturing the same.

Another object of the present invention is to provide a cellulose-based natural fiber and a method for producing the same, which induces cellulose degradation of cellulose-based natural fiber to reduce the degree of polymerization of cellulose.

Another object of the present invention is to provide a cellulose-based natural fiber and a method for manufacturing the same, by adjusting the size of pores formed in the cellulose-based natural fiber by varying the irradiation intensity of the electron beam.

In addition, another object of the present invention is to produce a cellulose-based natural fiber and a functional group having a porous structure by irradiating a high energy beam to the cellulose-based natural fiber and at the same time a functional group formed on the surface of the cellulose-based natural fiber to improve the reactivity with the polymer matrix To provide a method.

In addition, another object of the present invention is to apply a dry method using a high energy beam to the surface treatment of cellulose-based natural fibers in the energy consumption and chemical solution treatment by cellulose-based natural fiber drying, which has been a disadvantage of wet methods such as alkaline solution treatment To provide a cellulose-based natural fiber manufacturing method that can prevent the environmental pollution.

The present invention to achieve the object as described above and to solve the problems of the conventional cellulose in the low intensity beam (10-200 kGy in the case of electron beam) according to the beam intensity irradiated when processing the cellulose-based natural fibers Impurity removal on the surface of the natural fiber and the formation of functional groups and the porous structure inside the cellulose-based natural fiber can be simultaneously formed.

The irradiation time of the electron beam is irradiated instantaneously by the irradiation apparatus, and there is no limitation on the time.

In addition, the pore size formed in the cellulose-based natural fibers can be adjusted according to the electron beam irradiation intensity.

In addition, irradiation with high intensity beams (200-500 kGy for electron beams) produces cellulose with an alpha cellulose content of less than 20%. In the case of 500 kGy or more, the shape of the pores is maintained, but the brittleness is increased, and the physical properties of the cellulose-based natural fibers, such as decrease in tensile strength and elastic strength, are reduced.

The electron beam generator as described above is a device that generates electron beams of high energy by accelerating light generated from electron guns in a vacuum state using a high voltage close to speed, and is applied to various industrial fields including basic science research. This device was used as a common electron accelerator to irradiate electron beams on cellulose-based natural fibers.

The functional group used in the present invention refers to an ester group (-C (= O) -O-), an ester group (COC), or a hydroxyl group (-C-OH-). However, this arrangement does not limit the entire functional group of the present invention, it is a matter of course that the functional group varies depending on the gas. By the production of this action, the adhesive property between the cellulose-based natural fiber reinforcement and the polymer matrix is improved.
The atmosphere when the electron beam is irradiated is performed under an air atmosphere.
In addition, the atmosphere upon irradiation of the electron beam is changed to nitrogen or argon, which is an inert atmosphere, to adjust the functional group properties of the surface.

Hereinafter, the configuration and the operation of the embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a comparative view of a cellulose-based natural fiber manufacturing method and a conventional chemical method according to the present invention, Figures 2a, b shows the surface and cross-sectional structure (SEM photograph) of the cellulose-based natural fiber treated in accordance with the present invention .

Specifically, Figure 1 shows the cellulose-based natural fiber treatment process by the conventional chemical method compared with the treatment process according to the present invention. As shown in the figure, the treatment process according to the present invention has no drying process, etc., compared to the cellulose-based natural fiber surface treatment by the chemical method, which is energy-saving, and the treatment method is simple, and there is no discharge of pollutants such as alkaline solution. It can be seen. In other words, it can be seen that the treatment method of the present invention consists of a simple method of irradiating high energy beams on cellulose-based natural fibers.

The surface and the cut surface of the cellulose-based natural fiber treated with the present invention and the conventional alkaline solution were observed with a scanning electron microscope to compare the removal of impurities on the surface of the cellulose-based natural fiber with the porous structure of the cellulose-based natural fiber. .

The results of this invention are shown in Figures 2a and b, and the results of the conventional method are shown in Figures 3a and b.

In the cellulose-based natural fiber treatment according to the present invention, by controlling the intensity of irradiation of the high energy beam, it is possible to simultaneously remove the impurities in the porous structure and the surface of the cellulose-based natural fiber and to generate functional groups (see Example 1). It is also possible to proceed with the degradation of the cellulose-based natural fibers by reducing (see Example 2).

Figure 4 shows a graph showing the degree of polymerization of the cellulose-based natural fiber is changed according to the irradiation beam intensity, showing the alpha and beta cellulose change characteristics of the cellulose-based natural fiber changed according to the irradiation beam intensity of the alpha and beta cellulose The molecular weight was measured by the TAPPI T230 om-99 method. Alpha cellulose is a large cellulose having a polymerization degree of 100 or more and a molecular weight of 16,200 or more, and beta cellulose is a small cellulose having a polymerization degree of 15 to 100. As shown in the figure, it can be seen that as the amount of radiation increases, the amount of alpha cellulose decreases and the amount of beta cellulose increases, which leads to the breakdown of the intermolecular linkage by irradiation of high energy beams. Because it has changed.

Figure 5 shows a graph showing the viscosity change characteristics of the cellulose-based natural fiber changed according to the irradiation beam intensity, showing that the viscosity decreases as the electron beam intensity increases. As described with reference to FIG. 4, the viscosity decreases as the degree of polymerization, ie, the molecular weight, decreases due to the change from alpha cellulose having a high degree of polymerization to beta cellulose having a low degree of polymerization by irradiation with a high energy beam.

Hereinafter, preferred examples and comparative examples of the present invention.

<Example 1>

Cellulose-based natural fibers were well arranged in a single layer and placed in polyethylene plastic bags, and the electron beam was irradiated between 10 kGy and less than 200 kGy at room temperature. 10, 30, 50, 70, 100, 150, 200, 500 and 2000 kGy were irradiated at the time of irradiation.

SEM observation of the surface and the cut surface of the cellulose-based natural fiber irradiated with the electron beam is shown in Example 1 in comparison with the cellulose-based natural fiber source sample.

As shown in the embodiment, the surface of the cellulose-based natural fiber source sample is covered with wax or impurities, and the inside has a structure filled with cellulose.

When the cellulose-based natural fiber is irradiated with a high energy beam of less than 200 kGy intensity, as shown in FIG.

The pore size increases as the intensity of irradiation increases, which is attributed to the breakdown of cellulose in the order of cellulose 1, cellulose 2, and cellulose 3, which are located on the innermost side of the microfibril.

In addition, the electron beam intensity of more than 100 KGy cross-linking between the cellulose (cross-linking) occurs, as shown in Figure 3, the cellulose is in close contact with the lignin portion, which was analyzed to improve the tensile strength and elastic properties of the fiber.

           (a) (b)

(Example 1) Surface (X500) and cross section (X1000) photograph of cellulose-based natural fiber raw material

              (a) (b)

(Example 2) Photograph of surface (X500) and cross section (X1000) of cellulose-based natural fiber irradiated with 50 kGy electron beam

             (a) (b)

(Example 3) Photograph of surface (X500) and cross section (X1000) of cellulose-based natural fiber irradiated with 100 kGy electron beam

<Example 2>

Cellulose-based natural fibers were well arranged in a single layer and then placed in polyethylene plastic bags, and then irradiated with an electron beam of 500 kGy or more at room temperature.

In the embodiment, the beam was irradiated in the range of 500 kGy to 2000 kGy, and the content of alpha cellulose and beta cellulose could not be measured in this section. This is because the cellulose structure is destroyed by a large dose.

The results of observing the surface and the cut surface of the cellulose-based natural fiber irradiated with the electron beam are shown in Example 4.

As shown in the embodiment, the surface of the cellulose-based natural fiber source sample can only observe the cellulose structure in which the uneven portion of the microfibrils is broken and adhered around the lignin even in the fracture surface.

As a result, it can be seen that a large pore structure with a diameter of 10 µm or more is formed inside the fiber, and many cracks are observed in the cellulose structure attached to the lignin by irradiation of a high energy beam. The degradation of cellulose by electron beam irradiation proceeded, and as a result, it was analyzed that the tensile strength and elastic properties of cellulose-based natural fibers were also reduced. In other words, the pores and physical properties of the cellulose-based natural fibers are maintained up to 500 kGy, but even if there are pores, the basic physical properties of the cellulose-based natural fibers are reduced.

          (a) (b)

(Example 4) Photograph of surface (X500) and cross section (X1000) of cellulose-based natural fiber irradiated with 500 kGy electron beam

Comparative Example 1

Cellulose-based natural fiber treatment method that has been generally used up to now is a chemical treatment using an alkaline solution, the method is as follows.

Soak cellulose-based fiber in NaOH aqueous solution (concentration less than 10 wt%) for 1 hour, wash off the alkaline component with water, neutralize it for about 10 minutes in 2 wt% acetic acid solution, and then clean cellulose-based fiber again with distilled water. Wash it.

Cellulose-based natural fibers completely removed from alkali and acidic components are dried in air for several days, and then dried in a dryer maintained at 105 ° C to 110 ° C for at least one hour before being used as a reinforcement material to completely remove moisture in the cellulose-based fiber. Remove it.

Cellulose-based natural fibers produced by this chemical treatment method has functional groups on the surface, but as shown in Comparative Example 1, the cellulose-based natural fibers are swelled during drying and shrinkage during drying while the cellulose-based natural fibers are contained in an alkaline solution. Its pore structure is destroyed, making it difficult to form a porous structure.

In addition, when immersed in a strong alkaline solution (10 wt% or more NaOH aqueous solution) or when the strong alkali component directly touches the fiber, as shown in Comparative Example 2, the fiber itself may bend or break.

              (a) (b)

(Comparative Example 1) Surface (X500) and cross-sectional (X1000) photographs of cellulose-based natural fibers treated by a chemical method (treated for 1 hour in 5% aqueous NaOH solution)

             (a) (b)

Comparative Example 2 Surface (X500) and Cross Section (X1000) Photographs of Cellulose Natural Fibers Treated with Strong Alkaline Solution (1 Hour in 10% NaOH Aqueous Solution)

As described above, it can be seen that the present invention provides a cellulose-based natural fiber having a porous structure, which can not be achieved by the conventional chemical treatment method as in the comparative example, and that the size of the pores can be controlled by the intensity of the irradiation beam. Can be. In addition, it can be seen that the tensile strength and elastic properties can be adjusted according to the intensity of the irradiation beam.

The present invention can be used as a reinforcement of the polymer composite material for interior and exterior materials of the automotive and building industries.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

Cellulose-based natural fiber processing method of the present invention as described above has a variable size of 5 ~ 20 ㎛ inside the fiber at the same time as removing impurities and functional groups on the surface of the cellulose-based natural fiber by controlling the irradiation intensity of the high energy beam It is possible to manufacture porous cellulose-based natural fibers,

In addition, when the porous cellulose-based natural fiber according to the present invention is used as a reinforcing material for polymer composite materials for interior and exterior materials of the automobile and building industries, the sound absorption and shock mitigation effect due to the porous structure of the fiber may be expected. With the advantage that

In addition, the method for producing a porous cellulose-based natural fiber according to the present invention is a dry method as compared to the conventional treatment method with an alkaline solution, energy saving properties and no environmental pollutants, such as alkaline solution, is very environmentally friendly Useful inventions with great advantages are inventions that are highly expected for industrial use.

Claims (8)

Method of producing a cellulose-based natural fiber having a porous structure, characterized in that by irradiating the surface of the cellulose-based natural fiber with an electron beam to remove the impurities on the surface and at the same time to form a functional group while forming a porous structure inside the cellulose-based natural fiber . The method of claim 1, The intensity of the electron beam is a method for producing a cellulose-based natural fiber having a porous structure, characterized in that to have a porous structure inside the cellulose-based natural fiber by irradiating an electron beam of less than 10 KGy ~ 200 KGy. The method of claim 1, The intensity of the electron beam is a method of producing a cellulose-based natural fiber having a porous structure, characterized in that to have a porous structure inside the natural fiber by irradiating an electron beam of less than 10 KGy ~ 500 KGy. The method of claim 2, The method of manufacturing a cellulose-based natural fiber having a porous structure characterized in that to control the pore size by irradiating an electron beam to the cellulose-based natural fiber to cause any one of decomposition or cross-linking of the cellulose structure. The method of claim 3, wherein Cellulose-based natural fiber having a porous structure characterized in that by irradiating an electron beam to the cellulose-based natural fiber to control the pore size by causing any one of degradation of the cellulose structure, cross-linking, deterioration by the degree of polymerization Manufacturing method. The method according to any one of claims 1 to 5, The atmosphere at the time of irradiating the said electron beam is a manufacturing method of the cellulose-type natural fiber which has a porous structure characterized by performing in air atmosphere. The method according to any one of claims 1 to 5, The method of manufacturing a cellulose-based natural fiber having a porous structure, characterized in that the atmosphere upon irradiation of the electron beam is adjusted to nitrogen or argon which is an inert atmosphere to control the functional group properties of the surface. Cellulose-based natural fibers having a porous structure, characterized in that the porous structure is formed inside the cellulose-based natural fibers prepared by the method of any one of claims 1 to 5.

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