KR-20260065700-A - Method for manufacturing nanocellulose-based electromagnetic shielding sheet and electromagnetic shielding sheet prepared thereby

Abstract

The present invention relates to a method for manufacturing a nanocellulose-based electromagnetic shielding sheet and an electromagnetic shielding sheet manufactured thereby. A method for manufacturing a nanocellulose-based electromagnetic shielding sheet according to one embodiment of the present invention comprises: a first step of preparing a first solution containing cellulose nanofibers (CNF); a second step of preparing a mixed solution by mixing a second solution containing graphene with the first solution; and a third step of manufacturing a sheet by filtering and drying the mixed solution.

Inventors

• 이칠형
• 하태원
• 임대윤
• 김영백
• 정채환
• 박민준
• 윤성민

Assignees

• 한국생산기술연구원

Dates

Publication Date

20260511

Application Date

20241101

Claims (17)

1. A first step of preparing a first solution containing cellulose nanofibers (CNF); A second step of preparing a mixed solution by mixing a second solution containing graphene with the first solution; and A method for manufacturing a nanocellulose-based electromagnetic shielding sheet comprising: a third step of filtering and drying the above-mentioned mixed solution to produce a sheet.
2. In Article 1, A method for manufacturing a nanocellulose-based electromagnetic shielding sheet, characterized in that the first step above is a step of preparing a first solution in which the cellulose nanofiber powder is homogeneously dispersed by stirring a suspension containing cellulose nanofiber (CNF) powder at 30 to 150 rpm for 10 to 30 minutes.
3. In Article 1, A method for manufacturing a nanocellulose-based electromagnetic shielding sheet, characterized in that the mixed solution of the second step above is a mixture of the first solution and the second solution in a volume ratio of 1:0.01 to 0.05.
4. In Article 1, A method for manufacturing a nanocellulose-based electromagnetic shielding sheet, characterized by further including a step of stirring the mixed solution at 30 to 150 rpm for 10 to 30 minutes after the second step and before performing the third step.
5. In Article 1, A method for manufacturing a nanocellulose-based electromagnetic shielding sheet, characterized in that the third step above involves mixing the mixed solution prepared in the second step with a solvent and filtering it through a hydrophilic nylon-based filter having a thickness of 0.3 to 0.6 μm.
6. In Paragraph 5, A method for manufacturing a nanocellulose-based electromagnetic shielding sheet, characterized in that, in the third step above, the mixed solution and the solvent are mixed in a volume ratio of 1:0.2 to 2 and filtered.
7. In Article 1, A method for manufacturing a nanocellulose-based electromagnetic shielding sheet, characterized by further including a step of drying at 100 to 150°C for 8 to 15 hours after the third step above.
8. A nanocellulose-based electromagnetic shielding sheet characterized by being manufactured by a method for manufacturing a nanocellulose-based electromagnetic shielding sheet according to any one of claims 1 to 7.
9. In Paragraph 8, A nanocellulose-based electromagnetic shielding sheet comprising graphene evenly dispersed between cellulose nanofibers (CNF), having an average pore size of 5 to 20 nm and a BET specific surface area of 2 m²/g or more.
10. In Paragraph 8, A nanocellulose-based electromagnetic shielding sheet characterized by having a Young's modulus of 10 GPa or more.
11. In Paragraph 8, A nanocellulose-based electromagnetic shielding sheet characterized by having a tensile strength of 70 MPa or more.
12. A first step of preparing a first solution containing cellulose nanofibers (CNF); A second step of filtering and drying the first solution to produce a sheet; A method for manufacturing a nanocellulose-based electromagnetic shielding sheet, comprising: a third step of completing the sheet by spray-coating a second solution containing graphene onto the sheet and drying it at least once.
13. In Paragraph 12, A method for manufacturing a nanocellulose-based electromagnetic shielding sheet, characterized in that the first step above is a step of preparing a first solution in which the cellulose nanofiber powder is homogeneously dispersed by stirring a suspension containing cellulose nanofiber (CNF) powder at 30 to 150 rpm for 10 to 30 minutes.
14. In Paragraph 12, A method for manufacturing a nanocellulose-based electromagnetic shielding sheet, characterized in that the second step above involves mixing the first solution prepared in the first step with a solvent and filtering it through a hydrophilic nylon-based filter having a thickness of 0.3 to 0.6 μm.
15. In Paragraph 14, A method for manufacturing a nanocellulose-based electromagnetic shielding sheet, characterized in that, in the second step above, the first solution and the solvent are mixed in a volume ratio of 1:0.2 to 2 and filtered.
16. In Paragraph 12, In the third step above A method for manufacturing a nanocellulose-based electromagnetic shielding sheet characterized by drying at 90 to 150℃ for 0.5 to 3 hours.
17. A nanocellulose-based electromagnetic shielding sheet characterized by being manufactured by a method for manufacturing a nanocellulose-based electromagnetic shielding sheet according to any one of claims 12 to 16.

Description

Method for manufacturing nanocellulose-based electromagnetic shielding sheet and electromagnetic shielding sheet prepared thereby The present invention relates to a method for manufacturing a nanocellulose-based electromagnetic shielding sheet and an electromagnetic shielding sheet manufactured thereby. More specifically, the invention relates to a method for manufacturing a nanocellulose-based electromagnetic shielding sheet capable of simultaneously satisfying ultra-thin thickness (50 μm or less), product uniformity, and electromagnetic shielding performance, and an electromagnetic shielding sheet manufactured thereby. Cellulose is an organic compound that exists in large quantities in nature, second only to coal, and is a very important industrial resource. As a polysaccharide that serves as the main component of the cell walls of higher plants and occupies most of the woody tissue, cellulose makes up approximately 50% of wood and 98% of cotton. Its chemical structure consists of chains formed by the polymerization of multiple D-glucose units linked by β-1,4 bonds. In addition to higher plants, it is found in bacteria, seaweed, and the exoskeletons of seafood such as sea squirts; it is also contained in the exocrine secretions of acetic acid bacteria and exists in the form of cellulose sulfate esters within the mucus of shellfish. This cellulose is an odorless white solid that is insoluble in water and highly resistant to alkali, but it is hydrolyzed into glucose in acid. Additionally, cellulose is broken down by cellulases from fungi, bacteria, mollusks, etc., and eventually becomes glucose. Because cellulose has strong resistance to chemicals and is not corroded by microorganisms, in addition to being used as a raw material for paper and clothing, cellulose derivatives are being applied in various fields. In other words, nanocellulose, derived from cellulose, is an organic polymer material with excellent tensile strength and is an eco-friendly renewable resource because it is obtained from natural materials such as various types of wood and plant resources. The application of nanocellulose in polymer composites can not only significantly improve the mechanical strength of polymers but is also widely used in packaging materials for food and pharmaceuticals due to its low air permeability, excellent mechanical properties, and transparent optical properties. Furthermore, due to its low coefficient of thermal expansion, it has high potential for application in lithium-ion battery separators, displays, solar cells, electronic paper, and sensors. Accordingly, research is actively being conducted to realize various composite materials using nanocellulose, metal nanoparticles, or carbon materials; however, conventional methods mainly involve manufacturing composite materials through processes that simply mix nanocellulose and carbon materials to achieve specific properties. In this case, due to the weak intramolecular adsorption forces between nanocellulose and carbon materials, it is difficult to form a random structure and produce a uniformly dispersed form (i.e., the formation of numerous aggregates). Furthermore, when manufacturing in film form, there is a problem where a low concentration of carbon material (e.g., graphene) is loaded onto the nanocellulose film, leading to a deterioration in the physical properties of the composite. Therefore, research and methods to overcome the aforementioned problems are urgently required in the industry. FIG. 1 is an image showing a mixed solution in which a second solution containing graphene is mixed with a first solution containing cellulose nanofibers (CNF) according to a comparative example or one embodiment of the present invention. FIG. 2 is a schematic diagram showing a filtration process according to a comparative example or an embodiment of the present invention. FIG. 3 is an image showing the drying step of a cellulose nanofiber sheet and a nanocellulose-based electromagnetic shielding sheet according to a comparative example to an embodiment of the present invention. FIG. 4 is an image showing a cellulose nanofiber sheet and a nanocellulose-based electromagnetic shielding sheet according to a comparative example to an embodiment of the present invention. FIG. 5 is an image of a cellulose nanofiber sheet and a nanocellulose-based electromagnetic shielding sheet having flexibility and handling stability according to a comparative example to an embodiment of the present invention. FIG. 6 is an AFM and SEM analysis image evaluating the surface characteristics of a cellulose nanofiber sheet and a nanocellulose-based electromagnetic shielding sheet according to a comparative example to an embodiment of the present invention. Figure 7 is a graph showing the BET surface area of a cellulose nanofiber sheet according to a comparative example of the present invention. Figure 8 is a graph showing the BET surface area of a nanocellulose-based electromagnetic shielding