TW202204505A - Nanocellulose pieces, nanocellulose piece manufacturing method, polymer composite material, and polymer composite material manufacturing method - Google Patents

Abstract

Provided is a polymer composite material or the like containing nanocellulose pieces that can be dispersed in a molten polymer. The polymer composite material contains: a matrix thermoplastic resin that serves as a base material; and flake-like nanocellulose pieces including cellulose nanofibers or cellulose nanocrystals obtained by binding, through covalent bonds or hydrogen bonds, molecules of a thermoplastic resin that is compatible with said matrix thermoplastic resin. The nanocellulose pieces are dispersed in the matrix thermoplastic resin.

Description

Nanocellulose sheet, manufacturing method of nanocellulose sheet, polymer composite material and manufacturing method of polymer composite material

The present invention relates to a nanocellulose sheet mixed with a polymer composite material, a manufacturing method of the nanocellulose sheet, a polymer composite material containing the nanocellulose sheet, and a manufacturing method of the polymer composite material.

The industry traditionally manufactures composite materials of nanofibers such as cellulose nanocrystals and polymers. For example, Patent Document 1 discloses a method of adding and kneading nanofibers as a filler to a melted polymer. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 6256644

[The problem to be solved by the invention]

However, when nanofibers such as cellulose nanocrystals are added to the melted polymer and kneaded, the nanofibers are still aggregated with each other, and there is a disadvantage that the nanofibers cannot be dispersed in the polymer.

The present invention is made in view of the above-mentioned conventional problems, and hereby provides a nanocellulose sheet with high dispersibility for molten thermoplastic resin, a method for producing the nanocellulose sheet, and the nanocellulose sheet The purpose of this invention is to provide a polymer composite material of a sheet and a method for producing the polymer composite material. [Means of Solving Problems]

In order to solve the above problem, the nanocellulose sheet of the present invention is characterized by containing cellulose nanocrystals or cellulose nanofibers and formed into a sheet shape, and the cellulose nanocrystals or cellulose nanofibers are formed by Molecules of a thermoplastic resin having compatibility with the matrix thermoplastic resin to be reinforced are covalently or hydrogen bonded.

The nanocellulose sheet of the present invention contains cellulose nanocrystals or cellulose nanofibers bound to the molecules of the thermoplastic resin by covalent bonds or hydrogen bonds. By melt-mixing or dissolving-mixing the nanocellulose sheet and the thermoplastic resin, the dispersibility of the nanocellulose sheet to the thermoplastic resin can be improved.

In addition, the polymer composite material of the present invention is characterized by comprising: a matrix thermoplastic resin, which is used as a base material; and a nanocellulose sheet, which contains cellulose nanocrystals or cellulose nanofibers, and is In the form of flakes, the cellulose nanocrystals or cellulose nanofibers are bonded with the molecules of the thermoplastic resin having compatibility with the matrix thermoplastic resin through covalent bonds or hydrogen bonds, and the nanocellulose sheets are dispersed in the aforementioned matrix thermoplastic resin.

The polymer composite material according to the present invention is a sheet-like nanocellulose sheet having nanocellulose in which molecules of the thermoplastic resin having compatibility with the matrix thermoplastic resin are bonded by covalent bonds or hydrogen bonds. That is, since the thermoplastic resin bound to the nanocellulose sheet has compatibility with the matrix thermoplastic resin, the dispersibility of the nanocellulose sheet to the matrix thermoplastic resin can be improved. Thus, the mechanical properties of the polymer composite material, especially the toughness, can be improved.

In the polymer composite material of the present invention, preferably, the molecular system of the thermoplastic resin having compatibility with the aforementioned matrix thermoplastic resin has the same molecular structure as the aforementioned matrix thermoplastic resin.

In the polymer composite material of the present invention, it is preferable that the aforementioned matrix thermoplastic resin has a molecular structure without hydrophilic groups, and the molecules having compatibility with the aforementioned matrix thermoplastic resin are chemically modified functional groups through co-polymerization. The valence bonds allow the cellulose nanocrystals or cellulose nanofibers to be modified.

In the polymer composite material of the present invention, preferably, the aforementioned matrix thermoplastic resin is polyolefin, and the aforementioned nanocellulose sheet is a cellulose nanoparticle modified by a covalent bond and a maleic acid-modified polyolefin. Crystalline or cellulose nanofibers are formed.

In the polymer composite material of the present invention, preferably, the aforementioned matrix thermoplastic resin is polypropylene.

In the polymer composite material of the present invention, preferably, the matrix thermoplastic resin has a molecular structure including a hydrophilic group, and the nanocellulose sheet is composed of cellulose nanocrystals or cellulose nanofibers. Cellulose nanocrystals or cellulose nanofibers are modified by hydrogen bonding of the hydrophilic groups through molecules having compatibility with the thermoplastic resin.

In the polymer composite material of the present invention, preferably, the aforementioned thermoplastic resin is polylactic acid.

In the polymer composite material of the present invention, it is preferable that the thickness of the aforementioned nanocellulose sheet is 1-1000 nm.

The method for producing nanocellulose sheets of the present invention is characterized by comprising: a dispersing solution preparation step of dissolving cellulose nanocrystals or cellulose nanofibers in a solvent to prepare a nanocellulose dispersion solution; resin particles The dispersing step is to disperse particles of thermoplastic resin having functional groups that can bond with the cellulose nanocrystals or the cellulose nanofibers in the nanocellulose dispersion solution; the drying step is to disperse the nanoparticles The solvent of the rice cellulose dispersion solution is heated and dried to obtain a dried product of cellulose nanocrystals or cellulose nanofibers containing molecules modified with the thermoplastic resin by covalent bonds or hydrogen bonds; and a pulverization step, which is The aforementioned dried product is pulverized to form a flake-like nanocellulose sheet.

According to the manufacturing method of the nanocellulose sheet of the present invention, by dissolving cellulose nanocrystals or cellulose nanofibers in a solvent, the nanocrystals or cellulose nanofibers dispersed in the solvent A network of nanocellulose can be formed in the cellulose dispersion solution. If particles of a thermoplastic resin having a functional group capable of forming covalent bonds or hydrogen bonds with cellulose nanocrystals or cellulose nanofibers are mixed with this dispersion solution, the particles of the thermoplastic resin can be dispersed in this dispersion solution . That is, the particles of the thermoplastic resin are introduced into the network structure of the nanocellulose. When the solvent of this dispersion solution is heated and dried, a dried product having a thermoplastic resin in the core and nanocellulose in the shell can be obtained. In this drying step, the molecules of the thermoplastic resin of the core are modified with the nanocellulose of the shell by covalent bonds or hydrogen bonds. When the dried product is pulverized, the shells of the particles composed of nanocellulose modified by the molecules of the thermoplastic resin by covalent bonds or hydrogen bonds are destroyed, and a sheet-like nanocellulose sheet can be obtained.

In the manufacturing method of the nanocellulose sheet of the present invention, the aforementioned pulverization step is preferably performed by a jet mill.

The method for producing a polymer composite material of the present invention is characterized by comprising making the nanocellulose sheet compatible with the molecules of the thermoplastic resin modified by covalent bonds or hydrogen bonds. The matrix thermoplastic resin is subjected to a mixing step of melt mixing or solution mixing.

According to the polymer composite material of the present invention, the nanocellulose sheet is melt-mixed with a matrix thermoplastic resin having compatibility with the molecules of the thermoplastic resin modified by covalent bonds or hydrogen bonds in the nanocellulose sheet, or By dissolving and mixing, a polymer composite material with high dispersibility of the nanocellulose sheet can be obtained. As a result, a polymer composite material in which the nanocellulose sheets are uniformly dispersed in the matrix thermoplastic resin can be obtained.

[Form of implementing the invention]

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. However, these can be appropriately changed and combined. In addition, in the following description and drawings, the same reference numerals are attached to substantially the same or equivalent parts for description.

FIG. 1 shows a schematic diagram of the polymer composite material 100 of the present invention. As shown in FIG. 1 , the polymer composite material 100 includes: a matrix thermoplastic resin 10 as a base material to be reinforced; and a nanocellulose sheet 20 as a reinforcing material dispersed in the matrix thermoplastic resin 10 .

The matrix thermoplastic resin 10 has, for example, a molecular structure that does not contain a hydrophilic group. The matrix thermoplastic resin 10 having a molecular structure without a hydrophilic group is not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene, polystyrene, and polyvinyl chloride. Among them, polypropylene is particularly preferred. .

The matrix thermoplastic resin 10 may have, for example, a molecular structure including a hydrophilic group. It does not specifically limit as a matrix thermoplastic resin which has a molecular structure containing a hydrophilic group, For example, polylactic acid, polyhydroxyalkanoic acid, polycaprolactone, polyurethane, acrylic resin, etc. are mentioned. For example, polylactic acid or polyhydroxyalkanoic acid is preferably used when biodegradability, which is a characteristic of polymer composite materials, is to be obtained.

The nanocellulose sheets 20 are dispersed in the matrix thermoplastic resin 10 . The nanocellulose sheet 20 is a cellulose nanocrystal or cellulose nanofiber (hereinafter referred to as nanocellulose) in which the molecules of the thermoplastic resin having compatibility with the matrix thermoplastic resin 10 are bound by covalent bonds or hydrogen bonds. ) and formed into flakes.

Cellulose nanocrystals are, for example, crystalline nanocelluloses obtained by treating wood cellulose with sulfuric acid, and are needle-like substances having a width in the range of 5 to 50 nm and a length in the range of 100 to 200 nm. The cellulose nanocrystal system is measured with an atomic force microscope (AFM: Atomic Force Microscope), and the average length calculated by the image analysis is preferably 60 to 500 nm, more preferably 100 to 500 nm. In addition, the average diameter of the cellulose nanocrystals calculated by the above-mentioned image analysis is preferably 2 to 30 nm, more preferably 2 to 15 nm.

Cellulose nanofibers are, for example, fibrous substances composed of crystalline nanocellulose that can be obtained by treating wood cellulose by a physical fiber dissociation method or a chemical fiber dissociation method. The cellulose nanofibers are measured with an electron microscope, and the average length calculated by the image analysis is preferably 1 μm or more, and more preferably 5 μm or more. In addition, the average fiber diameter of the cellulose nanofibers calculated by the above-mentioned image analysis is preferably 2 to 100 nm, more preferably 2 to 50 nm.

When the molecular structure of the matrix thermoplastic resin 10 does not have a hydrophilic group, as the molecule of the thermoplastic resin having compatibility with the matrix thermoplastic resin 10, a thermoplastic resin modified with a functional group capable of forming a chemical bond with the matrix thermoplastic resin can be used. As an example of such a thermoplastic resin, maleic acid modified polypropylene is mentioned, for example. Maleic acid-modified polypropylene is, for example, produced by the reaction of maleic anhydride and polypropylene, and has a molecular structure represented by the following chemical formula 1.

The nanocellulose system of maleic acid-modified polypropylene bonded by covalent bond has the molecular structure shown in the following chemical formula 2.

When the molecular structure of the matrix thermoplastic resin 10 has a hydrophilic group, as the molecule of the thermoplastic resin having compatibility with the matrix thermoplastic resin 10, a thermoplastic resin having a hydrophilic group is similarly exemplified. As an example of such a thermoplastic resin, polylactic acid is mentioned, for example. The nanocellulose system in which polylactic acid is hydrogen-bonded has a molecular structure represented by the following chemical formula 3.

The thickness of the nanocellulose sheet 20 is preferably 1-1000 nm, preferably 5-1000 nm, more preferably 5-500 nm, still more preferably 5-100 nm. In addition, the thickness of the nanocellulose sheet 20 can be measured by an image analysis method using an electron microscope.

Hereinafter, the manufacturing method of the polymer composite material 100 described above will be described. FIG. 2 is a flowchart showing the procedure of manufacturing the polymer composite material 100 .

As shown in FIG. 2 , a dispersion solution preparation step of dissolving nanocellulose in a solvent to prepare a nanocellulose dispersion solution is performed (step S01 ).

By dissolving the nanocellulose 21 in the solvent, the nanocellulose network structure is formed in the nanocellulose dispersion solution in which the nanocellulose 21 is dispersed in the solvent. The mesh structure has voids inside.

As a vehicle of the nanocellulose dispersion solution, for example, water can be used. Nanocellulose can be contained in the solvent at 1.0 to 4.9 mass %, more preferably 2.0 to 4.0 mass %, and still more preferably 2.5 to 3.0 mass %.

A resin particle dispersion step of dispersing particles of a thermoplastic resin having a functional group capable of bonding with the nanocellulose 21 in the nanocellulose dispersion solution is performed (step S02). In this case, the particle diameter of the particles of the thermoplastic resin may be 0.5 to 200 μm, more preferably 0.5 to 50 μm, and more preferably 0.5 to 10 μm. In addition, the mass ratio of the particles of the thermoplastic resin to the nanocellulose may be 2 times or more, more preferably 4 times or more, and even more preferably 10 times or more. In other words, the mass ratio of thermoplastic resin to nanocellulose can be 10:0.5-10:5, preferably 10:0.5-10:3, more preferably 10:0.5-10:1.0. In addition, the shape of the particle is not particularly limited, and, for example, any of a spherical shape, an ellipsoid shape, a needle shape, and a fiber shape can be employed.

FIG. 3 is a schematic diagram showing the state of the nanocellulose 21 . As shown in FIG. 3 , if particles of thermoplastic resin 22 having functional groups that can form covalent bonds or hydrogen bonds with nanocellulose 21 are mixed with the nanocellulose dispersion solution obtained in step S01, the The particles will be dispersed in this dispersion solution. That is, the particles of the thermoplastic resin 22 are introduced into the inside of the network structure of the nanocellulose 21 .

A drying step of heating and drying the solvent of the dispersion solution to obtain a dried product of nanocellulose containing thermoplastic resin molecules modified by covalent bonds or hydrogen bonds is performed (step S03 ).

When the solvent of the dispersion solution obtained in step S02 is heated and dried, a dried product having the thermoplastic resin 22 in the core and the nanocellulose 21 in the shell can be obtained. In this drying step, the molecules of the thermoplastic resin of the core are modified with the nanocellulose 21 of the shell by covalent bonds or hydrogen bonds. Specifically, on the inner wall surface 23 of the nanocellulose 21 (the part of the interface (the core/shell composite microparticles)), for example, maleic acid-modified polypropylene forms chemical bonds with the cellulose nanocrystals. In addition, the dry matter contains, for example, nanocellulose sheets, nanocellulose, maleic acid-modified polypropylene, and nanocellulose containing maleic acid-modified polypropylene.

The pulverization step of pulverizing the dried material to form a flake-like nanocellulose sheet is performed (step S04). In step S04, the pulverization of the dried material is preferably performed by a jet mill. By pulverizing the dried material by the jet mill, the temperature rise of the dried material can be suppressed to prevent melting, and the dried material can be pulverized by colliding with each other.

In addition, when pulverizing the dried product with a jet mill, the size of the dried product can be adjusted in advance to a size suitable for the use of the jet mill. Adjustment of the size of the dried product can be performed using an appropriate device such as a mixer. This operation is hereinafter referred to as fragmentation.

FIG. 4 is a schematic diagram showing the state of nanocellulose. As shown in FIG. 4 , the dried material is pulverized by a jet mill. For example, the maleic acid-modified polypropylene of the core is released to the outside of the nanocellulose 21 of the shell to generate nanometer-sized nanometer-sized nanofibers. Cellulose sheet 20. In other words, the nanocellulose 21 of the shell is peeled off from the maleic acid-modified polypropylene of the core to form the nanocellulose sheet 20 .

When the dried product is pulverized in this way, the shells of the particles composed of the nanocellulose 21 in which the molecules of the thermoplastic resin are bonded by covalent bonds or hydrogen bonds are destroyed, and the sheet-like nanocellulose sheet 20 can be obtained. .

Carry out the mixing step of melt-mixing or dissolving-mixing the nanocellulose sheet obtained in step S04 with the thermoplastic resin having compatibility with the molecules of the thermoplastic resin modified on the nanocellulose sheet by covalent bonds or hydrogen bonds ( Step S05).

In the step S05, the nanocellulose sheet 20 can be easily dispersed in the thermoplastic resin because the nanocellulose sheet 20 is modified with the molecules of the thermoplastic resin having compatibility with the matrix thermoplastic resin 10 by covalent bonds or hydrogen bonds. As a result, the dispersibility of the nanocellulose sheet 20 to the matrix thermoplastic resin 10 can be improved.

As mentioned above, the nanocellulose sheet 20 of the present invention makes the molecules of the thermoplastic resin modify the nanocellulose by covalent bonds or hydrogen bonds. The dispersibility of the nanocellulose sheet 20 in the matrix thermoplastic resin 10 can be improved by melt-mixing or dissolving-mixing the nanocellulose sheet 20 and the matrix thermoplastic resin 10 .

The polymer composite material 100 according to the present invention is a sheet-like nanocellulose sheet having nanocellulose in which molecules of the thermoplastic resin having compatibility with the matrix thermoplastic resin 10 are bound by covalent bonds or hydrogen bonds 20. That is, the thermoplastic resin bonded to the nanocellulose sheet 20 has compatibility with the matrix thermoplastic resin 10, so that the dispersibility of the nanocellulose sheet 20 to the matrix thermoplastic resin 10 can be improved. Thus, the mechanical properties of the polymer composite material, especially the toughness, can be improved.

According to the manufacturing method of the polymer composite material 100 of the present invention, the nanocellulose sheet 20 has a matrix compatible with the molecules of the thermoplastic resin modified the nanocellulose sheet 20 by covalent bonds or hydrogen bonds. The thermoplastic resin 10 is melt-mixed or dissolved-mixed to obtain a polymer composite material with high dispersibility of the nanocellulose sheet 20 to the matrix thermoplastic resin 10 . As a result, the polymer composite material 100 in which the nanocellulose sheets 20 are uniformly dispersed in the matrix thermoplastic resin 10 can be obtained. [Example] [Test Example 1] (Nanocellulose sheet of maleic acid modified polypropylene) (Manufacture of Nanocellulose Sheets)

Maleic acid modified polypropylene (MAPP) particles and cellulose nanocrystals (CNC) were prepared as raw materials. The mixing ratios of maleic acid-modified polypropylene (MAPP) particles and cellulose nanocrystals (CNC) were 10:3, 10:2, 10:1, and 10:0.8. These four kinds of nanocellulose sheets were prepared.

As the cellulose nanocrystal system, one with an average length of 200 nm and an average diameter of 15 nm measured by an atomic force microscope (AFM) method was used. As the maleic acid-modified polypropylene, the average particle diameter measured by the laser light scattering method was 30 μm.

The cellulose nanocrystals are dispersed in water, and the dispersion solution preparation step is performed. Specifically, 100 mL of deionized water was prepared in a 300 mL Erlenmeyer flask, and stirring was started with a magnetic stirrer (product name: F-604N, manufactured by Tokyo Glass Instrument Co., Ltd.). 1 to 5 g of CNC (manufactured by Celluforce) were added and dispersed in accordance with Table 1 while stirring.

A resin particle dispersion step was performed by dispersing maleic acid-modified polypropylene having an average particle diameter of 30 μm in the dispersion solution. In the step of dispersing the resin particles, four kinds of dispersion solutions with different concentrations were prepared in such a way that the maleic acid-modified polypropylene and the cellulose nanocrystals reached the above ratio. Specifically, while stirring with a magnetic stirrer (product name: F-604N, manufactured by Tokyo Glass Machinery Co., Ltd.), maleic acid-modified polypropylene (product name: MG400P, manufactured by RIKEN VITAMIN Co., Ltd.) was gradually added in small amounts. system).

A drying step of heating and drying the solvent of the dispersion solution to obtain a dried product is performed. Specifically, the dispersion was transferred to a shallow dish, covered with aluminum foil, punched, and dried at 80°C. Then, the dried material was disintegrated using a mixer.

A pulverization step of pulverizing the dried material to form a flake-like nanocellulose sheet is performed. The pulverizing step is performed using a jet mill. A jet mill (product name: Typhoon, manufactured by Isaac) was used; the setting of the jet mill was a treatment speed of 20 g/hour.

(Observation of the state of the particles of the dried product) The state of the particles of the dried product was observed with a scanning electron microscope (hereinafter referred to as SEM). The type of SEM and the measurement environment are as follows. SEM: JEOL JSM-5600LV Pressurized voltage: 15kV Conductive treatment of sample: Au sputtering 200Å

(Condition of turbid liquid) Table 1 shows the dispersion state of maleic acid-modified polypropylene and cellulose nanocrystals in the resin particle dispersion step. In addition, the evaluation criteria of the dispersion state in the table are shown below. In addition, CNC in the table is "cellulose nanocrystal", and MAPP is "maleic acid-modified polypropylene".

(assessment benchmark) ×: Separation of CNC and maleic acid modified polypropylene △: Partial separation of CNC and maleic acid modified polypropylene 〇: CNC and maleic acid modified polypropylene are uniformly mixed

As shown in Table 1, in Examples 3 and 4, extremely good dispersion states were obtained. In addition, in Examples 1 and 2, a dispersion state superior to that in Comparative Examples 1 and 2 was obtained. On the other hand, in Comparative Example 1, the CNC was cloudy and a good dispersion state could not be obtained. In addition, in Comparative Example 2, the maleic acid-modified polypropylene remained in the upper part, and it was difficult to stir.

(Observation of dried particles by SEM) FIG. 5 is a SEM image (800 times) of the dried product before the pulverization step, showing the ratio of maleic acid-modified polypropylene to cellulose nanocrystals of 10:3. 6 is a dried product after the pulverization step, showing an SEM image (800 times) of a sample in which the ratio of maleic acid-modified polypropylene and cellulose nanocrystals is 10:3.

FIG. 7 is a SEM image (800 magnifications) of a sample whose ratio of maleic acid-modified polypropylene and cellulose nanocrystals is 10:2 of the dried product before the pulverization step. 8 is a dried product after the pulverization step, showing an SEM image (800 times) of a sample in which the ratio of maleic acid-modified polypropylene and cellulose nanocrystals is 10:2.

FIG. 9 is a SEM image (800 times) of the dried product before the pulverization step, showing the ratio of maleic acid-modified polypropylene and cellulose nanocrystals of 10:1. 10 is a dried product after the pulverization step, showing an SEM image (800 times) of a sample in which the ratio of maleic acid-modified polypropylene and cellulose nanocrystals is 10:1.

FIG. 11 is a dried product before the pulverization step, showing an SEM image (800 times) of a sample in which the ratio of maleic acid-modified polypropylene and cellulose nanocrystals is 10:0.8. 12 is a dried product after the pulverization step, showing an SEM image (800 times) of a sample in which the ratio of maleic acid-modified polypropylene and cellulose nanocrystals is 10:0.8.

As shown in FIGS. 5 to 12 , the particle size of the dried product after the pulverization step was confirmed to be smaller than that of the dried product before the pulverization step at any ratio. In addition, it was confirmed that the dried product after the pulverization step had slightly rounded corners compared with the dried product before the pulverization step. In particular, as shown in Figures 6, 8, 10 and 12, the dried product after the pulverization step was confirmed to have the shell of nanocellulose damaged, and it was judged that the maleic acid-modified polypropylene of the core component was peeled off. The particle sheet of the pores formed at the time, that is, the nanocellulose sheet.

FIG. 13 is a dried product after the pulverization step, showing an SEM image (1600 times) of a sample having a ratio of maleic acid-modified polypropylene and cellulose nanocrystals of 10:3. FIG. 14 is a dried product after the pulverization step, showing an SEM image (1600 times) of a sample having a ratio of maleic acid-modified polypropylene and cellulose nanocrystals of 10:2.

FIG. 15 is the dried product after the pulverization step, showing the SEM image (1600 times) of the sample in which the ratio of maleic acid-modified polypropylene and cellulose nanocrystals is 10:1. FIG. 16 is a dried product after the pulverization step, showing an SEM image (1600 times) of a sample in which the ratio of maleic acid-modified polypropylene and cellulose nanocrystals is 10:0.8.

As shown in FIGS. 13 to 16 , a nanocellulose sheet formed by peeling off the cellulose nanocrystals of the shell component from the maleic acid-modified polypropylene of the core component was confirmed. It was confirmed that the smaller the content ratio of cellulose nanocrystals to maleic acid-modified polypropylene, the thinner the nanocellulose sheet was. This is because it is concluded that as the content ratio of cellulose nanocrystals to maleic acid-modified polypropylene decreases, the thickness of the shell formed by cellulose nanocrystals becomes thinner.

(Manufacture of polymer composite materials) The dried product and polypropylene were melt-mixed to obtain a polymer composite material. The mixing ratio of maleic acid modified polypropylene, cellulose nanocrystals and polypropylene is 12:1.2:90. The melt-mixing system was kneaded at 180° C. using a twin-screw extruder (product name: LABO PLASTOMILL, manufactured by Toyo Seiki Co., Ltd.). Then, it shape|molded by the vacuum heating press at 180 degreeC into the pellet shape of φ13mm and thickness 2mm.

In addition, the samples were prepared as sample A (Comparative Example 3) containing only polypropylene, Sample C (Comparative Example 4) containing only the dried product produced without the pulverization step and polypropylene, and the dried product including the pulverized product and the polypropylene. Three kinds of propylene sample B (Example 5).

(Stretching test) Tensile tests were performed to measure strain versus stress. The settings of the tensile tester are as follows. Chuck Spacing: 32mm Marking spacing: 22mm Test speed: 10mm/min Load cell used: 1kN

FIG. 17 shows the measurement results of strain versus stress in Comparative Example 3. FIG. FIG. 18 shows the measurement results of strain versus stress in Comparative Example 4. FIG. FIG. 19 shows the measurement results of strain versus stress in Example 5. FIG. As shown in FIGS. 17 to 19 , the maximum stress of Example 5 is higher than that of Comparative Examples 3 and 4. Moreover, Example 5 can apply strain longer than Comparative Example 4.

(Discussion on the influence of the thickness of the nanocellulose sheet on the physical properties) The polymer composite materials of Comparative Examples 5 and 6 and Examples 6 to 8 were prepared according to the following methods. In addition, the manufacturing method of a dried material is the same as the above-mentioned method, and the description is abbreviate|omitted. In addition, the preparation method of each comparative example and each Example is the same as the above-mentioned method, and the description is abbreviate|omitted.

As Comparative Example 5, pellets were prepared using only polypropylene. As Comparative Example 6, a pellet obtained by melt-mixing a sample and polypropylene, which is a dried product before the pulverization step and has a ratio of maleic acid-modified polypropylene and cellulose nanocrystals of 10:2, was produced. In addition, the ratio of maleic acid-modified polypropylene, cellulose nanocrystals and polypropylene is 10:2:90.

As Example 6, a pellet obtained by melt-mixing a sample and polypropylene, which is a dried product after the pulverization step and has a ratio of maleic acid-modified polypropylene and cellulose nanocrystals of 10:2, was produced. In addition, the ratio of maleic acid-modified polypropylene, cellulose nanocrystals and polypropylene is 10:2:90.

As Example 7, a pellet obtained by melt-mixing a sample and polypropylene, which is a dried product after the pulverization step and has a ratio of maleic acid-modified polypropylene to cellulose nanocrystals of 10:1.2, was produced. In addition, the ratio of maleic acid-modified polypropylene, cellulose nanocrystals and polypropylene is 10:1.2:90.

As Example 8, a pellet obtained by melt-mixing a sample and polypropylene, which is a dried product after the pulverization step and has a ratio of maleic acid-modified polypropylene to cellulose nanocrystals of 10:1.2, was produced. In addition, the ratio of maleic acid-modified polypropylene, cellulose nanocrystals and polypropylene is 10:1:90.

The above-described tensile test was performed on Comparative Examples 5 and 6 and Examples 6 to 8. The obtained physical properties are shown in Table 2 based on the results.

As shown in Table 2, as the content ratio of cellulose nanocrystals to maleic acid-modified polypropylene decreases, in other words, as the thickness of the nanocellulose sheet decreases, the elongation at break can be largely maintained and the elasticity can be improved. Modulus and yield stress increase.

[Test Example 2] (Nanocellulose sheet of polylactic acid) (Manufacture of Nanocellulose Sheets) Cellulose nanocrystals (CNC) and polylactic acid (PLA: polylactic acid) particles were prepared as raw materials. The mixing ratio of cellulose nanocrystals (CNC) and polylactic acid (PLA) particles was 10:1 to prepare nanocellulose sheets.

As the cellulose nanocrystal system, one having an average length of 200 nm and an average diameter of 15 nm measured by an atomic force microscope (AFM: Atomic Force Microscope) was used. Polylactic acid (product name: REVODE110, manufactured by Zhejian Hisun Biomaterials) was used with an average particle diameter of 50 μm measured by a laser light scattering method.

The cellulose nanocrystals are dispersed in water, and the dispersion solution preparation step is performed. Specifically, 300 mL of deionized water was placed in a separable flask, and stirring was started with a magnetic stirrer (product name: F-604N, manufactured by Tokyo Glass Instrument Co., Ltd.). While stirring, 9 g of CNC (product name: NCV-100, manufactured by Celluforce) was added and dispersed.

A resin particle dispersion step was performed by dispersing polylactic acid (product name: REVODE110, manufactured by Zhejian Hisun Biomaterials) having an average particle diameter of 50 μm in the dispersion solution. In the resin particle dispersion step, a dispersion solution was prepared so that the mass ratio of polylactic acid and cellulose nanocrystals was 10:1. Specifically, polylactic acid (product name: REVODE110, manufactured by Zhejian Hisun Biomaterials) was added little by little while stirring with a magnetic stirrer (product name: F-604N, manufactured by Tokyo Glass Instrument Co., Ltd.).

A drying step of heating and drying the solvent of the dispersion solution to obtain a dried product is performed. Specifically, the dispersion liquid was transferred to a shallow dish, covered with aluminum foil, punched, and dried at 80° C. for 2 days. Then, the dried material was disintegrated using a mixer.

The pulverization step of pulverizing the dried material to form a flake-like nanocellulose sheet is performed. Since the equipment used is the same as that of Test Example 1, the description thereof is omitted. The jet mill was set at a processing speed of 30 g/hr.

(Observation of the state of dried particles) The state of the dried particles was observed under the same SEM and the same conditions as in Test Example 1.

FIG. 20 is a dried product before the pulverization step, showing an SEM image (800 times) of a sample having a ratio of cellulose nanocrystals to polylactic acid of 10:1. 21 is a dried product after the pulverization step, showing an SEM image (1600 magnifications) of a sample in which the ratio of cellulose nanocrystals to polylactic acid is 10:1.

As shown in FIGS. 20 and 21 , it was confirmed that the particle size of the particles of the dried product after the pulverization step was smaller than that of the particles of the dried product before the pulverization step. In addition, it was confirmed that the particles of the dried product after the pulverization step had slightly rounded corners compared with the particles of the dried product before the pulverization step. In particular, as shown in FIG. 21 , the dried product after the pulverization step was confirmed to have a broken shell composed of nanocellulose, and the particle sheet with pores formed when the polylactic acid of the core component was peeled off was also confirmed. Namely, nanocellulose sheets. The dry product contains nanocellulose containing nanocellulose sheets, nanocellulose, polylactic acid and polylactic acid.

(Measurement of particle size distribution) FIG. 22 shows the particle size distribution of particles of the dried product measured by the laser light scattering method. As shown in FIG. 22 , the particle diameter of the particles of the dried product was confirmed to be 10 to 100 μm. In addition, the median diameter (D50) of the particles of the dried product was confirmed to be 35.4 μm.

(Manufacture of polymer composite materials) The polymer composite material of polylactic acid and dried product is produced by solvent casting method.

In addition, the samples were prepared as a sample D (Comparative Example 7) containing only polylactic acid, a sample E (Comparative Example 8) containing only the dried product produced without the pulverization step and polylactic acid, and the dried product including the pulverized product and polylactic acid. Three kinds of lactic acid sample F (Example 9). In addition, the mixing ratio of the polylactic acid and the dried product of Comparative Example 8 and Example 9 was 11:89.

Specifically, the above-mentioned material was added to chloroform, mixed, and dissolved so that the material would be 3%. 10 ml of this solution was poured into a petri dish, and it was naturally dried to form a thin film. This film was vacuum-dried at 70°C. The film thickness of the film after vacuum drying was 50 μm.

(Dynamic viscoelasticity measurement) Dynamic viscoelasticity measurements were performed to measure strain versus stress. The settings for the dynamic viscoelasticity measurement are as follows. Sample length: 10mm Strain: 14μm Frequency: 10Hz Temperature range: 30～200℃ Heating rate: 2°C/min

Figure 23 shows temperature versus storage elastic modulus. Figure 24 shows temperature versus loss tangent. As shown in FIG. 23 and FIG. 24 , the Young's modulus near room temperature of Example 9 including the dried product after the pulverization step was increased by 23% from that of Comparative Example 7 without the dried product.

In addition, the peak temperature of the loss tangent of Example 9 was 86 degreeC. In addition, the peak temperature of the loss tangent of Comparative Example 7 was 77°C. When the peak temperature of the loss tangent is regarded as the glass transition temperature (Tg), it can be confirmed that the glass transition temperature (Tg) of Example 9 is higher than that of Comparative Example 7 by 9°C.

In addition, the peak value of the loss tangent of Example 9 was 0.22. The peak value of the loss tangent of Comparative Example 7 was 0.29. The peak value of the loss tangent of Comparative Example 8 was 0.31. Therefore, it was confirmed that the peak value of the loss tangent of Example 9 was lower than that of Comparative Examples 7 and 8. That is, Example 9 is less likely to slide at the interface between cellulose nanocrystals and polylactic acid, and is more elastic than Comparative Examples 7 and 8 (similar to a spring state).

100: Polymer Composites 10: Thermoplastic resin 20: Nanocellulose sheet

Fig. 1 is a schematic diagram showing the concept of the polymer composite material of the present invention. [ Fig. 2 ] is a flow chart showing the production steps of the polymer composite material. FIG. 3 is a schematic diagram showing the state of the cellulose nanocrystals or cellulose nanofibers in step S02 of FIG. 2 . Fig. 4 is a schematic diagram showing the state of the cellulose nanocrystals or cellulose nanofibers in step S04 of Fig. 2 . [ Fig. 5 ] is an SEM image (800 times) of the dried product in which the ratio of maleic acid-modified polypropylene and cellulose nanocrystals is 10:3 before the pulverization step. [ Fig. 6 ] is an SEM image (800 times) of the dried product with the ratio of maleic acid-modified polypropylene and cellulose nanocrystals of 10:3 after the pulverization step. [ Fig. 7 ] is an SEM image (800 times) of the dried product with a ratio of maleic acid-modified polypropylene and cellulose nanocrystals of 10:2 before the pulverization step. [ Fig. 8 ] It is an SEM image (800 times) of the dried product with the ratio of maleic acid-modified polypropylene and cellulose nanocrystals of 10:2 after the pulverization step. [ FIG. 9 ] It is an SEM image (800 times) of the dried product in which the ratio of maleic acid-modified polypropylene and cellulose nanocrystals is 10:1 before the pulverization step. [ Fig. 10 ] It is an SEM image (800 times) of the dried product having a ratio of maleic acid-modified polypropylene and cellulose nanocrystals of 10:1 after the pulverization step. [ Fig. 11 ] is an SEM image (800 times) of the dried product in which the ratio of maleic acid-modified polypropylene and cellulose nanocrystals is 10:0.8 before the pulverization step. [ Fig. 12 ] is an SEM image (800 times) of the dried product in which the ratio of maleic acid-modified polypropylene and cellulose nanocrystals is 10:0.8 after the pulverization step. [ Fig. 13 ] is an SEM image (1600 times) of the dried product with a ratio of maleic acid-modified polypropylene and cellulose nanocrystals of 10:3 after the pulverization step. [ Fig. 14 ] is an SEM image (1600 times) of the dried product having a ratio of maleic acid-modified polypropylene and cellulose nanocrystals of 10:2 after the pulverization step. [ Fig. 15 ] is an SEM image (1600 times) of the dried product with a ratio of maleic acid-modified polypropylene and cellulose nanocrystals of 10:1 after the pulverization step. [ Fig. 16 ] is an SEM image (1600 magnifications) of the dried product having a ratio of maleic acid-modified polypropylene and cellulose nanocrystals of 10:0.8 after the pulverization step. FIG. 17 is a graph of measuring strain versus stress in Comparative Example 3. FIG. FIG. 18 is a graph of measuring strain versus stress in Comparative Example 4. FIG. FIG. 19 is a graph of measuring strain versus stress in Example 5. FIG. [ Fig. 20 ] It is an SEM image (800 times) of the dried product in which the ratio of polylactic acid to cellulose nanocrystals is 10:1 before the pulverization step. [ FIG. 21 ] is an SEM image (1600 times) of the dried product after the pulverization step in which the ratio of polylactic acid to cellulose nanocrystals is 10:1. Fig. 22 shows the particle size distribution measured by the laser light scattering method of the dried product in which the ratio of polylactic acid to cellulose nanocrystals is 10:1 after the pulverization step. [ Fig. 23 ] A graph showing temperature versus storage elastic modulus. [ Fig. 24 ] A graph showing temperature versus loss tangent.

10: Thermoplastic resin

20: Nanocellulose sheet

100: Polymer Composites

Claims (12)

A nanocellulose sheet is characterized in that it contains cellulose nanocrystals or cellulose nanofibers, and forms a sheet shape, and the cellulose nanocrystals or cellulose nanofibers are bonded by covalent bonds or hydrogen bonds Molecules of a thermoplastic resin having compatibility with the matrix thermoplastic resin to be reinforced. A polymer composite material, characterized by comprising: A matrix thermoplastic resin as the base material; and Nanocellulose sheet, which contains cellulose nanocrystals or cellulose nanofibers, and is in the form of flakes, and the cellulose nanocrystals or cellulose nanofibers are bonded with covalent bonds or hydrogen bonds with The aforementioned matrix thermoplastic resin has a compatible thermoplastic resin molecule, The aforementioned nanocellulose sheets are dispersed in the aforementioned matrix thermoplastic resin. The polymer composite material according to claim 2, wherein the molecular system of the thermoplastic resin having compatibility with the matrix thermoplastic resin has the same molecular structure as the matrix thermoplastic resin. The polymer composite material of claim 3, wherein, The aforementioned matrix thermoplastic resin system has a molecular structure without a hydrophilic group, The molecules of the thermoplastic resin having compatibility with the aforementioned matrix thermoplastic resin are bound to cellulose nanocrystals or cellulose nanofibers by covalent bonding through chemically modified functional groups. The polymer composite material of claim 4, wherein, The aforementioned matrix thermoplastic resin is a polyolefin, The aforementioned nanocellulose sheet is formed of cellulose nanocrystals or cellulose nanofibers bound with maleic acid-modified polyolefin by covalent bonds. The polymer composite material of claim 5, wherein, The aforementioned matrix thermoplastic resin is polypropylene, The aforementioned maleic acid-modified polyolefin is maleic acid-modified polypropylene. The polymer composite material of claim 3, wherein, The aforementioned matrix thermoplastic resin system has a molecular structure containing a hydrophilic group, The aforementioned nanocellulose sheet is composed of cellulose nanocrystals or cellulose nanofibers, and the cellulose nanocrystals or cellulose nanofibers are bonded with the aforementioned matrix thermoplastic through the aforementioned hydrophilic group and through hydrogen bonding. Resins are molecules of thermoplastic resins that are compatible. The polymer composite material according to claim 7, wherein the aforementioned matrix thermoplastic resin is polylactic acid. The polymer composite material according to any one of claims 2 to 8, wherein the thickness of the aforementioned nanocellulose sheet is 1-1000 nm. A manufacturing method of nanocellulose sheet, it is characterized in that comprising: Dispersion solution preparation step, which is to dissolve cellulose nanocrystals or cellulose nanofibers in a solvent to prepare a nanocellulose dispersion solution; The resin particle dispersing step is to disperse particles of thermoplastic resin having functional groups capable of bonding with the cellulose nanocrystals or the cellulose nanofibers in the nanocellulose dispersion solution; The drying step is to heat and dry the solvent of the nanocellulose dispersion solution to obtain cellulose nanocrystals or cellulose nanofibers containing molecules bound with the thermoplastic resin by covalent bonds or hydrogen bonds. dry matter; and The pulverization step is to pulverize the aforementioned dried material to obtain a flake-like nanocellulose sheet. The method for producing nanocellulose sheets according to claim 10, wherein the pulverizing step is performed by a jet mill. A method for producing a polymer composite material, characterized by comprising combining a nanocellulose sheet obtained by the method for producing a nanocellulose sheet according to claim 10 or 11, with a covalent bond or a hydrogen bond. The mixing step of melt-mixing or dissolving-mixing is performed on the matrix thermoplastic resin in which the molecules of the thermoplastic resin of the nanocellulose sheet are compatible.

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