Nanofiber reinforced PETG (polyethylene terephthalate glycol) composite material for 3D printing of large parts and preparation method of nanofiber reinforced PETG composite material

Abstract

The invention relates to the technical field of 3D printing materials, and belongs to a nanofiber reinforced PETG composite material for 3D printing of large parts and a preparation method thereof, and the nanofiber reinforced PETG composite material for 3D printing of large parts is a blend containing nanofibers treated by a physical modifier, PETG, a compatilizer and a plasticizer. The preparation method of the nanofiber reinforced PETG composite material comprises the following steps: preparing the modified nanofiber; blending the modified nanofiber, PETG, a compatilizer and a plasticizer through a high-speed mixer to form a blended material; carrying out melt blending extrusion and granulation on the blended material by using a twin-screw extrusion method; after being dried, the prepared composite material particles can be processed into monofilaments through a single-screw extruder, and the particles can also be directly used for 3D printing. According to the material disclosed by the invention, the tensile strength, the bending strength and the bending modulus of the material are improved by utilizing the characteristics of relatively high softening point of PETG and high rigidity of nano cellulose.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of 3D printing materials and belongs to a nanofiber reinforced PETG composite material for 3D printing of large parts and a preparation method thereof. BACKGROUND

[0002] 3D printing, a kind of rapid prototyping technology, is a technology for constructing objects through layer-by-layer printing based on digital model files and using powder-like metal or plastic and other bondable materials. The technology is applied in the fields of jewelry, footwear, industrial design, architecture, engineering and construction (AEC), automobiles, aerospace, dental and medical industries, education, geographic information systems, civil engineering and other fields. Fused deposition modeling (FDM) rapid prototyping is a method for accumulating and forming various thermoplastic filaments by heating and melting without relying on a laser as a forming energy.

[0003] The common 3D printing high polymer materials on the market at present mainly include PU (polyurethane), PETG (polyethylene terephthalate-1, 4-cyclohexane dimethyl ester), ABS (acrylonitrile-butadiene-styrene), PP (polypropylene) and PA (nylon), and the materials for 3D printing furniture should comprehensively consider the requirements of mechanical strength, weather resistance, environmental protection and sustainability. Among them, PLA is prone to degradation and aging, ABS has a large odor during printing, PP has a large deformation due to cooling shrinkage, and nylon has a high material cost, which limits the application of these materials in 3D printing furniture.

[0004] PETG, as a new 3D printing material, has the advantages of good aging resistance, good temperature resistance and easy post-processing, but has the disadvantages of strong plastic appearance and low mechanical properties, which limits the application of printed furniture.

[0005] At present, various types of gantry and mechanical arms have been developed for large part 3D printing, and the printing size has broken through the meter-level width, which brings possibilities for the development of 3D printing furniture technology. However, it is generally believed that wooden furniture is superior to plastic furniture in terms of use evaluation, and therefore, developing a material suitable for 3D printing of wooden furniture has become a demand of the industry. SUMMARY

[0006] In view of the above technical problems, the application provides a nanofiber reinforced PETG composite material for 3D printing of large parts and a preparation method thereof.

[0007] To achieve the above purpose, the application provides the following technical scheme: The application provides a nanofiber reinforced PETG composite material for 3D printing of large parts, which is a blend containing nanocellulose treated by a physical modifier, PETG, a compatibilizer and a plasticizer, wherein the content of the nanocellulose is 10wt%-20wt%, the content of the PETG is 70wt%-80wt%, the content of the compatibilizer is 1wt%-10wt%, and the content of the plasticizer is 1wt%-10wt%. The nanofiber reinforced PETG composite material for 3D printing of large parts is prepared by the following steps: S1, modifying nanofibers with a physical modifier; S2, blending the nanofibers modified in step S1, PETG, a compatibilizer and a plasticizer to form a blend; S3, melt blending and extruding the blend obtained in step S2 to obtain a base material of the nanofiber reinforced PETG composite material for 3D printing of large parts.

[0008] Preferably, the base material prepared in step S3 comprises particles and filaments; The particles are obtained by repeating extrusion twice, and the temperatures of the extruder at 1-6 segments are 150-160℃, 170-180℃, 200-220℃, 200-210℃, 180-190℃ and 180-185℃, respectively. The filaments are obtained by further processing the particles, and the diameter of the filaments is 2.85mm, and the diameter error is within-5%-5%.

[0009] Preferably, the compatibilizer is MAPP (maleic anhydride grafted polypropylene), and the plasticizer is PBAT (polybutylene terephthalate).

[0010] Preferably, the average diameter of the nanofibers is 20-100nm, the average length is 500nm-2μm, and the particle size of the nanofibers after drying is 60-80mesh.

[0011] Preferably, the physical modifier in step S1 is one or both of nanometer calcium carbonate and fumed silica, and the specific steps of modifying the nanofibers with the physical modifier are as follows: In the nanocellulose aqueous suspension, a physical modifier is added, and the nanocellulose aqueous suspension is uniformly stirred at room temperature, before the addition of the physical modifier, the solid content is adjusted to 3%, after the homogenization treatment, the nanocellulose aqueous suspension is uniformly scraped on the substrate, the coating film thickness is 3~5mm, and the coating film is naturally dried or heated to dryness to less than 5% of the water content, the dried nanocellulose film is dried to dryness at 80℃ and 0.6MPa vacuum conditions, and the nanocellulose film is ground to 60~80mesh to obtain nanocellulose powder.

[0012] Preferably, the particle size of the nanometer calcium carbonate is 1000~1500 mesh; the particle size of the fumed silica is 300~500 mesh; and the addition amount of the nanometer calcium carbonate and the fumed silica is 0.03%~0.15% of the mass of the nanocellulose aqueous suspension.

[0013] The application uses wood-derived nanofibers as reinforcing materials, and the nanofibers are physically modified to enhance the PETG material, and a significant technical effect is obtained. The application of nanofibers in the field of plastics such as PETG focuses on solving the physical agglomeration problem of nanofiber drying. Most of the relevant literature reports focus on chemical treatment of nanofibers, which has a long reaction time, residual chemical reagents, difficult purification, and high cost. The application reduces the interaction between hydrogen bonds of the fibers by physical isolation of nanometer inorganic materials. The nanofiber still shows good dispersion after drying, ensuring the reinforcing performance of high aspect ratio materials in thermoplastic materials.

[0014] The dispersion process of the nanofiber in the PETG matrix is mainly realized by using a double-screw extruder through melt blending multiple extrusions. During the blending process, processing aids such as compatibilizers and plasticizers are also added to improve the interfacial compatibility between the nanofiber and the matrix. The composite material after blending and extrusion has the surface texture of natural wood.

[0015] The nanofiber reinforced PETG composite material for large parts 3D printing of the application can be applied to large FDM 3D printers with a nozzle diameter of 3~5mm.

[0016] Compared with the prior art, the application provides a nanofiber reinforced PETG composite material for large parts 3D printing and a preparation method thereof, which has the following beneficial effects: (1) The tensile strength and bending strength of the composite material of the application meet the strength requirements of high-strength hardwood, and the wood texture is obvious. The impact resistance is much higher than that of ordinary PETG printing materials, and the composite material can be widely applied in the furniture industry.

[0017] (2) The composite material has the characteristics of not softening and deforming at high temperature, not easy to mildew, and not easy to be eaten by insects.

[0018] (3) The composite material has good post-processing performance such as paint coating and drilling.

[0019] The features and advantages of the present application will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 A flowchart of a preparation method of a nanofiber reinforced PETG composite material for large part 3D printing. DETAILED DESCRIPTION

[0021] To make the purpose, technical solutions and advantages of the present application clearer and more explicit, the present application will be further described in detail below with reference to the accompanying drawings and examples. However, it should be understood that the specific examples described herein are only used to explain the present application and do not limit the scope of the present application. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0022] The reagents used in the examples of the present application are commercially available conventional reagents or raw materials unless otherwise specified. The test methods used in the examples are conventional methods in the art unless otherwise specified. The specific method for testing the mechanical properties of the composite material is as follows: the tensile test is performed in accordance with the national standards GB / T 1040-2006 and GB / T 9341-2008.

[0023] A nanofiber reinforced PETG composite material for large part 3D printing, which is a blend containing nanocellulose treated with a physical modifier, PETG, a compatibilizer and a plasticizer, the content of the nanocellulose being 10wt%-20wt%, the content of the PETG being 70wt%-80wt%, the content of the compatibilizer being 1wt%-10wt%, and the content of the plasticizer being 1wt%-10wt%; Referring to Figure 1 , the nanofiber reinforced PETG composite material for large part 3D printing is prepared by the following steps: S1, modifying nanofibers with a physical modifier; S2, blending the nanofibers modified in step S1, PETG, a compatibilizer and a plasticizer to form a blend; S3, melt blending and extruding the blend obtained in step S2 to obtain a base material of the nanofiber reinforced PETG composite material for large part 3D printing.

[0024] Specifically, the base material prepared in step S3 includes particles and filaments; The particles are obtained by repeating the extrusion twice, and the temperatures of the 1-6 segments of the extruder are 150-160℃, 170-180℃, 200-220℃, 200-210℃, 180-190℃, and 180-185℃, respectively. The monofilament is obtained by further processing the particles, and the diameter of the monofilament is 2.85mm, and the diameter error is within -5% to 5%.

[0025] Specifically, the compatibilizer is MAPP (maleic anhydride grafted polypropylene), and the plasticizer is PBAT (polybutylene terephthalate).

[0026] Specifically, the average diameter of the single nanofiber is 20-100nm, the average length is 500nm-2μm, and the particle size of the dried nanofiber is 60-80mesh.

[0027] Specifically, the physical modifier in step S1 is one or both of nano calcium carbonate and fumed silica, and the specific steps for modifying the nanofiber with the physical modifier are as follows: In the aqueous nanocellulose suspension, the physical modifier is added, and the mixture is uniformly stirred at room temperature. Before the addition of the physical modifier, the solid content of the aqueous nanocellulose suspension is adjusted to 3%. After homogenization, the mixture is uniformly scraped onto a substrate, and the coating film thickness is 3-5mm. The coating film is naturally dried or heated to dryness to a water content of less than 5%. The dried nanofiber film is dried to dryness at 80℃ under a vacuum of 0.6MPa to obtain a nanocellulose film. The nanocellulose film is ground and broken to 60-80mesh to obtain nanocellulose.

[0028] Specifically, the particle size of the nano calcium carbonate is 1000-1500mesh, and the particle size of the fumed silica is 300-500mesh. The addition amount of the nano calcium carbonate and the fumed silica is 0.03%-0.15% of the mass of the aqueous nanocellulose suspension.

[0029] Example 1 A nanofiber reinforced PETG composite material for large part 3D printing is prepared according to the following steps: (1) Preparation of modified nanofiber; Physically modified nanofiber: 0.06% of nano calcium carbonate based on the aqueous nanocellulose suspension is added to a 3% concentration of nanocellulose suspension, stirred with a stirrer at 300rpm for 30min, then added to a high-pressure homogenizer for homogenization. The homogenization pressure is controlled at 20 standard atmospheres, and the homogenization is repeated twice. The mixture is uniformly scraped onto a steel plate, and the coating film thickness is maintained at 3-5mm. The mixture is naturally dried to a water content of less than 5%. The dried nanofiber is placed in a vacuum oven at 80℃ for further drying to dryness. The dried nanofiber is then ground with a high-speed grinder for use. (2) After drying, the nanofiber, PETG, compatibilizer MAPP, plasticizer PBAT were mixed together in a high-speed mixer for 5 min, and then taken out; the nanofiber content was controlled at 10 wt%, the PETG content was 80 wt%, the compatibilizer MAPP was added in an amount of 5 wt%, and the plasticizer PBAT was added in an amount of 5 wt%; (3) The mixture prepared in step (2) was added to an extruder for extrusion, and the extruded strands were cooled in water and then pelletized to obtain a composite masterbatch. After drying at 80°C for 24 h, the masterbatch was sealed and stored for later use; the temperature of each zone of the extruder was set to 150°C, 170°C, 200°C, 200°C, 180°C, and 180°C, respectively. The mechanical properties of the prepared composite particles were tested, and the tensile strength, bending strength, and bending modulus of the nanofiber reinforced PETG composite were all significantly improved compared to pure PETG. The tensile strength reached 50.9 Mpa, the bending strength reached 76 Mpa, and the bending modulus reached 2743.9 Mpa. The thermal deformation temperature was increased by 20%; (4) After drying, the pellets prepared in step (3) were directly used for 3D printing with a PETG pellet 3D printer, or further added to a single-screw extruder to draw 3D printing wire. The temperature of the feeding section, compression section, metering section, and cylindrical die of the extruder was set to 175°C, 200°C, 210°C, and 180°C, respectively (which can be adjusted according to actual conditions); the extruded melt was cooled and dried in a water tank, then passed through a traction machine to prepare a monofilament with a diameter of about 2.85 mm, and was wound and used for 3D printing with a wire large part 3D printer.

[0030] The modified nanofiber of step (1) in Example 1 can also be prepared by a physical modification method of fumed silica; (a) The addition amount of fumed silica was 0.06% of the nanocellulose aqueous suspension, and the other steps were the same as step (1) of Example 1; (b) The addition amount of nanometer calcium carbonate was 0.03% of the nanocellulose aqueous suspension, the addition amount of fumed silica was 0.03% of the nanocellulose aqueous suspension, and the other steps were the same as step (1) of Example 1.

[0031] Example 2 A nanofiber reinforced PETG composite material for large part 3D printing was prepared according to the following steps: (1) Preparation of modified nanofiber; Physical modification of nanofiber: 0.06% of nano calcium carbonate based on the aqueous suspension of nanocellulose was added to the nanocellulose suspension with a concentration of 3%, stirred with a stirrer at 300 rpm for 30 min, and then added to a high-pressure homogenizer for homogenization. The homogenization pressure was controlled at 20 standard atmospheres, and the homogenization was repeated twice. The uniform scraping was taken out and coated on a steel plate, the coating film thickness was kept at 3-5 mm, and the nanofiber was naturally dried to a water content of less than 5%. The dried nanofiber was placed in a vacuum oven at 80°C for further drying to dryness, and then taken out and crushed with a high-speed crusher for use; (2) The dried nanofiber, PETG, compatibilizer MAPP, and plasticizer PBAT were mixed together in a high-speed mixer for 5 min, and then taken out. The content of nanofiber was controlled at 15 wt%, the content of PETG was 75 wt%, the addition amount of compatibilizer MAPP was 5 wt%, and the addition amount of plasticizer PBAT was 5 wt%; (3) The mixture prepared in step (2) was added to an extruder for extrusion, and the extruded sample was cut into particles after water cooling to obtain a composite material master batch. After drying at 80°C for 24 h, it was sealed for standby use. The temperature of each zone of the extruder was set at 150°C, 170°C, 200°C, 200°C, 180°C, and 180°C, respectively. The mechanical properties of the prepared composite particles were tested. The tensile strength, bending strength, and bending modulus of the nanofiber reinforced PETG composite material were all improved compared with pure PETG. The tensile strength could reach 49.4 Mpa, the bending strength reached 75.3 Mpa, the bending modulus reached 2677.8 Mpa, the thermal deformation temperature increased by 30%, and the surface wood texture was stronger; (4) The granules prepared in step (3) were dried, directly printed with a PETG particle 3D printer, or further added to a single-screw extruder to draw 3D printing wire. The temperature of the feeding section, compression section, metering section, and cylindrical die of the extruder was set at 175°C, 200°C, 210°C, and 180°C, respectively (which can be adjusted according to the actual situation). The extruded melt was cooled and dried in a water tank, then passed through a traction machine to prepare a monofilament with a diameter of about 2.85 mm, and was wound and printed with a wire material 3D printer.

[0032] The modified nanofiber of step (1) in Example 2 can also be prepared by a physical modification method of fumed silica; (a) The addition amount of fumed silica was 0.06% of the aqueous suspension of nanocellulose, and the other steps were the same as step (1) of Example 2; (b) The addition amount of nano calcium carbonate was 0.03% of the aqueous suspension of nanocellulose, the addition amount of fumed silica was 0.03% of the aqueous suspension of nanocellulose, and the other steps were the same as step (1) of Example 2.

[0033] Example 3 A nanofiber reinforced PETG composite material for large part 3D printing is prepared according to the following steps: (1) Preparation of modified nanofiber; Physical modification of nanofiber: 0.06% of nano calcium carbonate based on nanocellulose aqueous suspension is added to a 3% concentration of nanocellulose suspension, stirred with a 300 rpm stirrer for 30 min, then homogenized in a high pressure homogenizer, the homogenization pressure is controlled at 20 standard atmospheres, and the homogenization is repeated twice. Take out and evenly scrape on a steel plate, the coating film thickness is maintained at 3-5 mm, and naturally dry to a moisture content of less than 5%, then dry the nanofiber in a vacuum oven at 80°C until dry, and then take out and use a high-speed pulverizer; (2) Mix the dried nanofiber, PETG, compatibilizer MAPP, and plasticizer PBAT together in a high-speed mixer according to the proportions, mix for 5 min, and then take out; the nanofiber content is controlled at 20wt%, the PETG content is 70wt%, the compatibilizer MAPP addition amount is 5wt%, and the plasticizer PBAT addition amount is 5wt%; (3) The mixture prepared in step (2) is added to an extruder for extrusion, the extruded strands are cooled in water, and then pelletized to obtain a composite material master batch. After drying at 80°C for 24h, seal for later use; the temperature of each zone of the extruder is set to 150°C, 170°C, 200°C, 200°C, 180°C, and 180°C, respectively. The mechanical properties of the prepared composite material particles are tested, the tensile strength, bending strength, and bending modulus of the nanofiber reinforced PETG composite material are comparable to those of pure PETG, the tensile strength can reach 43Mpa, the bending strength reaches 52Mpa, and the bending modulus reaches 1844.6Mpa, but the hot deformation temperature increases by 40%, the surface wood grain is further enhanced, the cooling speed is fast during 3D printing, and the dimensional accuracy is high; (4) After drying the granules prepared in step (3), directly use a PETG particle 3D printer to print, or further add to a single screw extruder to pull out 3D printing wire. The temperature of the feeding section, compression section, metering section, and cylindrical die of the extruder is set to 175°C, 200°C, 210°C, and 180°C, respectively (which can be adjusted according to actual conditions); the extruded melt is cooled in a water tank and air dried, then passed through a traction machine to prepare a single wire with a diameter of about 2.85mm, and then wound and used for large part 3D printing with a wire material.

[0034] The modified nanofiber of step (1) in Example 3 can also be prepared by a physical modification method of fumed silica; (a) The addition amount of fumed silica is 0.06% of the nanocellulose aqueous suspension, and the other steps are the same as step (1) of Example 3; (b) the amount of nano calcium carbonate added is 0.03% of the aqueous nanocellulose suspension, the amount of fumed silica added is 0.03% of the aqueous nanocellulose suspension, and the other steps are the same as step (1) of Example 3.

[0035] Comparative Example 1 A PETG composite material for large part 3D printing was prepared according to the following steps: (1) After drying, PETG, compatibilizer MAPP, and plasticizer PBAT were mixed together in a high-speed mixer at a ratio of 90wt% PETG, 5wt% compatibilizer MAPP, and 5wt% plasticizer PBAT for 5 minutes, and then removed; (2) The mixture prepared in step (1) was added to an extruder and extruded, and the extruded strands were cooled in water and then pelletized to obtain composite material pellets. After drying at 80℃ for 24 hours, the pellets were sealed and stored for later use. The temperature settings of the extruder were 150℃, 170℃, 200℃, 200℃, 180℃, and 180℃, respectively. The mechanical properties of the prepared composite material pellets were tested, and the tensile strength of the PETG composite material was 42.1Mpa, the bending strength was 53Mpa, the bending modulus was 1695.6Mpa, and the thermal deformation temperature was 72.5℃; (3) After drying, the pellets prepared in step (2) were directly used for 3D printing with a PETG pellet 3D printer, or were further added to a single-screw extruder to draw 3D printing wire. The temperature settings of the feeding section, compression section, metering section, and cylindrical die of the extruder were 175℃, 200℃, 210℃, and 180℃, respectively (which can be adjusted according to actual conditions). The extruded melt was cooled in a water tank and air-dried, and then passed through a traction machine to prepare a single filament with a diameter of about 2.85mm, which was then wound and used for large part 3D printing with a wire 3D printer.

[0036] The above is a detailed description of the nanofiber-reinforced PETG composite material for large part 3D printing, the preparation method, and the preparation process provided by the embodiments of the present application. The principles and implementation methods of the present application are described using specific examples. The description of the examples is only used to help understand the method and core idea of the present application. The above description is only a preferred embodiment of the present application and does not limit the present application. Any modification, equivalent replacement, and improvement made within the spirit and principles of the present application should be included in the protection scope of the present application.

[0037] Table 1. Mechanical property test data of each example and comparative example The following conclusions can be drawn from the test data in Table 1: from the comparison of Example 1 and Comparative Example 1, it can be concluded that the addition of modified nanofibers can significantly improve the tensile strength, bending strength and bending modulus of the PETG composite. And from the comparison of the data of Experimental Examples 1 to 3, it can be concluded that there is an optimal value for the addition amount of modified nanofibers.

[0038] Table 2. Test data of thermal deformation temperature performance of each example and comparative example The following conclusions can be drawn from the test data in Table 2: the addition of modified nanofibers can significantly improve the thermal deformation temperature of the PETG composite.

[0039] In summary: the nanofiber reinforced PETG composite prepared by the present application for 3D printing of large parts has excellent mechanical properties and high thermal deformation temperature.

[0040] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement or improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A nanofiber-reinforced PETG composite material for 3D printing of large parts, characterized in that: The nanofiber-reinforced PETG composite material for large-scale 3D printing is a blend containing nanocellulose, PETG, compatibilizer, and plasticizer treated with physical modifiers. The nanocellulose content is 10wt%~20wt%, the PETG content is 70wt%~80wt%, the compatibilizer content is 1wt%~10wt%, and the plasticizer content is 1wt%~10wt%. The nanofiber-reinforced PETG composite material for large-part 3D printing is prepared through the following steps: S1. Modify nanofibers with physical modifiers; S2. The modified nanofibers, PETG, compatibilizer and plasticizer from step S1 are blended to form a blend; S3. The blend obtained in step S2 is melt-blended and extruded to obtain the base material of nanofiber reinforced PETG composite material for 3D printing of large parts.

2. The nanofiber-reinforced PETG composite material for large-scale 3D printing as described in claim 1, characterized in that: The base material obtained in step S3 includes granules and monofilaments; The granules need to be extruded twice, with the extruder sections 1-6 having temperatures of 150-160℃, 170-180℃, 200-220℃, 200-210℃, 180-190℃, and 180-185℃, respectively. The monofilament is obtained by further processing of particles, and its diameter is 2.85 mm with a diameter error of -5% to 5%.

3. The nanofiber-reinforced PETG composite material for large-scale 3D printing as described in claim 1, characterized in that: The compatibilizer is maleic anhydride-grafted polypropylene, and the plasticizer is polyethylene terephthalate.

4. The nanofiber-reinforced PETG composite material for large-scale 3D printing as described in claim 1, characterized in that: The nanofibers have an average diameter of 20-100 nm and an average length of 500 nm-2 μm. After drying, the nanofiber particle size is 60-80 mesh.

5. The nanofiber-reinforced PETG composite material for large-scale 3D printing as described in claim 1, characterized in that: The physical modifier mentioned in step S1 is one or both of nano-calcium carbonate and fumed silica. The specific steps for modifying nanofibers with the physical modifier are as follows: A physical modifier is added to an aqueous suspension of nanocellulose, and the mixture is stirred at high speed at room temperature until homogeneous. Before adding the physical modifier, the solid content of the aqueous suspension of nanocellulose is adjusted to 3%. After homogenization, the mixture is evenly coated onto a substrate with a coating thickness of 3-5 mm. The film is then dried naturally or heated until the moisture content is below 5%. The dried nanofiber film is then dried at 80°C under a vacuum of 0.6 MPa until completely dry to obtain a nanocellulose film. The nanocellulose film is then ground and crushed to 60-80 mesh to obtain nanocellulose powder.

6. The nanofiber-reinforced PETG composite material for large-scale 3D printing as described in claim 5, characterized in that: The nano-calcium carbonate has a particle size of 1000~1500 mesh. The fumed silica has a particle diameter of 300-500 mesh. The amount of nano-calcium carbonate and fumed silica added is 0.03% to 0.15% of the mass of the nano-cellulose aqueous suspension.

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