KR101430556B1 - Fabrication method of thermoplastic nanofiber composites using cellulose nanofibers and thermoplastic synthetic polymeric fibers - Google Patents

Abstract

The present invention provides a method for producing thermoplastic nano fiber composite sheet on a sheet having a high strength, a high elastic modulus and an extremely low thermal expansion coefficient through a wet nonwoven process using cellulose nano fibers and thermoplastic synthetic polymer fibers as main components. The paper produced according to the present invention can be used as a next generation new material composite material having high performance which is not possessed by existing materials, and is sustainable and environmentally friendly.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing thermoplastic nano fiber composites using cellulose nanofibers and thermoplastic synthetic polymer fibers,

The present invention relates to a method for producing a thermoplastic nanocomposite having a high strength, a high elastic modulus and a very low thermal expansion coefficient through a wet-laid nonwoven process of cellulose nanofibers and synthetic polymer fibers, and more particularly, Preparing a cellulose nanofiber having an average diameter of 30 nm to 70 nm through a brazing process, preparing a dispersion by dispersing the prepared cellulose nanofiber and thermoplastic synthetic polymer fibers in water, Preparing a sheet-like nanocomposite by applying a pressure of 2 MPa to 300 MPa at a temperature of 150 to 250 DEG C to the sheet-like nanocomposite to melt the synthetic polymer fiber into a matrix having a composite structure A cellulose nano-fiber-reinforced thermoplastic nano-composite It is about the method.

The microfibrillating process technology makes it possible to superfine superfine materials such as cotton, rayon, and synthetic fibers such as PE, PP and PAN, as well as liquid crystalline polymer fibers such as aramid, It is a state-of-the-art technology for manufacturing core materials for nanocomposite sheets and nanocomposite.

Particularly, "cellulose nanofibers using microfibrillating process" has physical characteristics that can not be found in natural plant celluloses and is expected as a new functional material.

Cellulose is the most abundant natural polymer on the planet and is currently used in a variety of fields such as the paper and textile industry as well as the electronics industry. As the industry develops, the consumption of cellulose is also rapidly increasing. This is mainly derived from natural plant materials such as wood and cotton, but there is also a growing interest in cellulose produced by microorganisms due to the supply of raw materials and environmental problems.

In particular, the nano-structured fibrillated cellulose has a high modulus of 150-200 GPa and a high strength of 5 GPa as a reinforcing material for a composite material. It is superior to the physical properties of Kevlar fiber, which is one of the super fibers. It is nano-sized (thickness 10 to 100 nm) compared to ordinary carbon fiber and glass fiber, has a small coefficient of thermal expansion (0.1 ppm K ^-1 ) Possible, lightweight, low energy consumption, fairness is excellent. Therefore, if fiber diameter (nano size) and fiber aspect ratio (L / D) are controlled through excellent properties such as high crystallinity, tensile strength and elastic modulus of cellulose nano fiber and proper manufacturing process, Will be a very likely material to replace.

Composite materials made from 100% cellulose nanofibers having these advantages have been reported to have better physical properties than ordinary steels or magnesium alloys. However, since this composite material is composed of only 100% cellulose, it is known that a drying process and a compression process for a long time are required due to the characteristics of the manufacturing process, and that the composite material can be produced only in sheet form from the viewpoint of shape. In addition, this material has the disadvantage that it is not thermoplastic and can not be shaped to have various shapes (Marielle Henriksson et al., 2008; Istva? Siro et al., 2010).

Thermoplastic and thermosetting plastic composite materials reinforced with cellulose nanofibers have been confirmed to be environmentally friendly high performance new materials beyond the limits of conventional glass fiber reinforced composite materials. Due to the demand for light weight and high strength in accordance with the modern industrial development, cellulose nano fiber composites with high performance and high performance are used in industrial fields such as electric and electronic equipment, transportation equipment (automobile, aerospace, ship), civil engineering, It is possible to expand the application to core materials in special fields such as defense industry and medical industry prosthetic devices.

In the 21st century, research and development of green nanocomposite, which is a fusion of nanotechnology in the field of composite materials, is being pursued as a way to solve environmental problems, energy and resource problems. Cellulose nanofiber composites are likely to be positioned as high-performance composite materials that are environmentally friendly and economical as new sustainable new materials that go beyond the limits of conventional materials. Green complexes with these various physical properties ultimately can not be obtained from conventional materials, but they can not be obtained from conventional materials because of their high mechanical strength, high modulus of elasticity, and electrical properties, thermal conductivity and low coefficient of thermal expansion. to provide.

In the meantime, research has been conducted on cellulose nano-fiber composites in some advanced countries such as Japan, Europe, and the United States, and Innventia of Sweden has published a study on composite sheets made of 100% cellulose nanofibers that are stronger than metals such as aluminum and tin (Marielle Henriksson et al., 2008).

However, the research and development of thermoplastic composites using cellulose nanofibers is still in its infancy, and the use of polymers such as polyamides, polylactic acid, and polyvinyl alcohols for composites prepared by various methods such as solvent casting and melt compounding Experimental results have been reported (Istvan Siro et al., 2010).

However, in the process for producing a thermoplastic composite using conventional cellulose nanofibers, the amount of the nanocellulose discharged during dehydration and remaining in the final composite sheet during the wet nonwoven fabric process is less than 50% of the initial amount.

Accordingly, the inventors of the present invention have developed a new process technology for producing a sheet-like nanofiber composite by preparing cellulose nanofibers having physical properties of glass fiber or more and mixing the thermoplastic synthetic polymer fibers with the thermoplastic synthetic polymer fibers. The thermoplastic cellulose nano- High strength, high modulus of elasticity, and low thermal expansion coefficient. Further, it has been confirmed that this material has thermoplasticity and can be shaped to have various shapes by heat, thus completing the present invention.

The present invention relates to a process for producing a composite sheet comprising a cellulose nano fiber and a synthetic polymer fiber through a wet nonwoven process and melting the thermoplastic synthetic fiber component through a high temperature and high pressure molding process to convert it into a matrix having a composite structure, And a method for producing a thermoplastic nano fiber composite reinforced with cellulose nanofibers having an extremely low thermal expansion coefficient.

In order to solve the above problems, the present invention provides a method for producing cellulose nanofibers, comprising the steps of: 1) preparing a cellulose nanofiber having an average diameter of 30 nm to 70 nm through a microfibrillization process; 2) Preparing a dispersion liquid by dispersing the polymer fibers in water, 3) preparing and drying a sheet-like nanocomposite through a wet nonwoven process using the dispersion of step 2), and 4) And a step of applying a pressure of 2 MPa to 300 MPa to the composite at a temperature of 150 ° C to 250 ° C to melt the synthetic polymer fibers to convert the matrix into a matrix of a composite structure to provide a thermoplastic nano-composite reinforced with the cellulose nanofibers do.

The above step 1) is a step of preparing a cellulose nanofiber having an average diameter of 30 nm to 70 nm through a microfibrillization process.

The term "microfibrillating process" used in the present invention means a process for producing a cellulose nanofiber having a predetermined length by hydrolyzing and homogenizing pulp.

The enzyme used for the hydrolysis in the microfibrillation step of step 1) is preferably Novozym 476. Further, the hydrolysis is preferably carried out at 50 DEG C for 2 hours. The pulp used in step 1) may be sulfite pulp, soda pulp (AP), semi-chemical pulp, kraft pulp and the like, and particularly bleached sulfite pulp is preferable, but not limited thereto.

The hydrolyzed cellulose is microfibrillated to produce nanofibers having an average diameter of 30 nm to 70 nm. At this time, homogenization can be performed at 1,400-1,600 bar using a high-pressure homogenizer such as a Microfluidizer. Particularly when a Z-shaped chamber is used, it is preferable to use a Z-shaped chamber because the fibril effect is maximized. When the diameter is larger than 70 nm, the cellulose nanofibers have a low density and a small specific surface area, so that the mechanical properties of the composite are not significantly improved. The diameter of the nanofibers can be adjusted according to the number of passes through the high pressure homogenizer. The diameter of the nanofibers decreases as the number of passes increases, as the channel size of the chamber decreases, and as the pressure increases.

The step 2) is a step of dispersing the cellulose nanofibers and the thermoplastic synthetic polymer fibers prepared in the step 1) in water to prepare a dispersion. The solvent for dispersing the cellulose nanofibers is preferably water. Since the cellulose nanofibers are hydrophilic, they can not be evenly dispersed when a hydrophobic solvent is used.

The weight ratio of the cellulose nanofibers of the dispersion of step 2) to the synthetic polymer fibers having thermoplastic properties is preferably from 2: 8 to 4: 6. When the weight ratio of the cellulose nanofibers is less than 2: 8 (for example, 1: 9), the cellulose nanofibers are separated from each other by the difference in density between the cellulose nanofibers and the synthetic polymer fibers. When the weight ratio of cellulose nanofibers is larger than 4: 6 (for example, 5: 5), drainage is not good and the sheet curling phenomenon occurs severely during drying. This is because the water molecules remaining between the cellulose nanofibers act as adhesives connecting the fibers to form a hydrogen bonding network.

The synthetic polymer fiber used in the present invention is preferably a thermoplastic fiber and a material having good interfacial affinity with cellulose. The synthetic polymer fibers used may be polyamides, but are not limited thereto. The polyamide fiber length is preferably 0.4 mm to 1.0 mm. If the fiber length is longer than 1.0 mm, it is difficult to disperse the fiber length when mixed with water due to the long fiber length. If the fiber length is shorter than 0.4 mm, the formed sheet has insufficient morphological stability.

The dispersion of step 2) may further comprise a cationic polymer. This is to increase the tensile strength and tensile elastic modulus of the nanocomposite. Examples of usable cationic polymers include cationic polyacrylamide, polyethyleneimine, anionic starch, poly (diallylmethylammonium chloride), dialkylaminoalkyl (meth) -acrylamide, dialkylaminoalkyl (meth) -Acrylates, and copolymers of nonionic ethylenically unsaturated water-soluble monomers with monoethylenically unsaturated cationic monomers. In the examples of the present invention, a cationic polyacrylamide was used.

The cationic polymer functions as a retention enhancer and forms a bond between the nanofibers by the electrostatic attraction with the cellulose nanofibers. Accordingly, retention of the cellulose nanofibers is increased during sheet formation, so that a high-density cellulose nanofiber layer can be formed in the sheet.

The preferred concentration of the cationic polymer is 0.1 wt% to 0.3 wt%. When the concentration is less than 0.1% by weight, a sufficient amount of retention does not occur, and when the concentration is higher than 0.3% by weight, curling becomes severe due to excessive retention.

Step 3) is a step of preparing and drying a sheet-like nanocomposite through a wet nonwoven process using the dispersion of step 2). The term " wet nonwoven fabric process " used in the present invention means a process in which fiber is dispersed in a solvent, water is selectively removed to obtain a uniform sheet-like fibrous structure, and then the sheet is formed into a sheet by a press roll.

It is preferable that the drying of the step 3) causes the moisture content of the sheet to be less than 1%. The drying is preferably carried out at room temperature to 80 ° C for 3 to 24 hours. Drying temperature and time will affect the moisture content of the final sheet, and at high temperatures above 80 캜, the sheet may warp due to rapid drying and may have undesirable effects on physical properties.

Between the preparation of the sheet-like nanocomposite of step 3) and the drying, by wet-pressing. Wet pressing is a process for preventing curling of a sheet produced by applying a pressure at a high temperature state before drying the manufactured sheet and increasing the density. The pressing may be performed using a hot press, but is not limited thereto. The volume of pores between the cellulose nanofibers and the synthetic polymer fibers generated during the wet nonwoven fabric process is reduced through the compression step, and the interfacial wettability is improved. The higher the temperature and the pressure of the pressing step, the better.

Step 4) is a step of applying a pressure of 2 MPa to 300 MPa at a temperature of 150 ° C to 250 ° C to the sheet-like nanocomposite of step 3) to melt synthetic polymer fibers to convert the matrix into a composite matrix. Due to the temperature and pressure, the synthetic polymer fibers are melted and impregnated, and the impregnated synthetic polymer fibers together with the cellulose nanofibers form a nanofiber composite. Representative processes of high-temperature and high-pressure molding to apply the temperature and pressure include, but are not limited to, a calendering process and a pressing process.

According to one concrete example, when the sheet-like nanofiber composite was prepared by mixing the cellulose nanofibers and the synthetic polymer fibers at a ratio of 2: 8 to 4: 6, the tensile strength and the tensile elastic modulus were increased (FIG. 3B). At this time, tensile strength and tensile elastic modulus increased with increasing cellulose nano fiber content, and showed the highest physical properties at 4: 6. In addition, when nanofiber composites composed of cellulose nanofibers and synthetic polymer fibers were prepared by adding cationic polyacrylamide, tensile strength and tensile elastic modulus were increased as compared with the case where cationic polyacrylamide was not added (Fig. 4B )

The nanofiber composite produced according to the present invention has thermoplasticity and can be shaped to have various shapes by heat. In a specific embodiment of the present invention, it was confirmed that the nanofiber composite of the present invention can be thermoformed using a mold at 250 ° C.

The sheet-like nanofiber composite composed of the cellulose nanofiber and the thermoplastic synthetic polymer fiber according to the present invention has high strength, high elastic modulus and extremely low thermal expansion coefficient, and can be used as a sustainable and environmentally friendly new-generation new material composite material.

1 is an SEM photograph of the cellulose nanofiber prepared in Example 1. Fig.
Fig. 2 is a photograph before and after drying of the cellulose nano fiber / polyamide composite sheet prepared according to the ratio of Example 2 (a. Basis weight 300 g / m ² , b. Basis weight 600 g / m ² ).
FIG. 3 is a photograph (a) before and after drying of the cellulose nano fiber / polyamide composite sheet produced according to Example 3 and the tensile properties (b) and the SEM photographs of the surface and the fracture surfaces of the nanofiber composite prepared from the (c).
Fig. 4 shows a photograph (a) before and after drying of a cellulose nano fiber / polyamide composite sheet containing a cationic polyacrylamide and a tensile property (b) of a nanofiber composite prepared from the photograph.
5 shows a mold (a) used in the thermoforming of a nanofiber composite produced according to the present invention and a tube (b) formed using the same.
6 is a cross-sectional SEM image of a cellulose nanofiber (CNF) / PAB (4: 6) composite paper produced according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided to further understand the present invention, and the present invention is not limited by the examples.

Example  One: Microfibrillation  Fabrication of Cellulose Nanofibers Using Process

Cellulose nanofibers were prepared according to the method developed by Innventia of Sweden. The wood pulp was first bleached with sulfuric acid and then dissociated through mechanical cleavage. The dissociated fibers were hydrolyzed with the enzyme Novozym 476 at 50 < 0 > C for 2 hours.

Subsequently, the fibril effect was maximized by passing through a high-pressure homogenizer at 1,400-1,600 bar. Cellulose nanofibers having an average diameter of 70 nm were prepared through the homogenization process.

The characteristics of the fibers produced through the above process were analyzed. The average diameter of the fabricated fibers was 70 nm, and the content of the cellulose nanofibers was 24 g / L. SEM photographs of the manufactured fibers are shown in Fig.

Example  2: Dispersion of Cellulose Nano Fiber / Synthetic Polymer Fiber and Production of Composite Sheet

Two types of polyamide fibers were prepared for the production of cellulose nano-fiber / synthetic polymer fiber composite sheet. In this case, one is a polyamide fiber (PA) having a fiber length of 0.4 mm and 1.5 denier, and the other is a polyamide fiber (hereinafter referred to as a PAB) having a fiber length of 1.0 mm and 1.5 denier.

To analyze the binding characteristics of the composite sheet, the surface charge of the prepared polyamide fibers (PA, PAB) was analyzed. The results of the analysis are shown in Table 1.

division Surface charge Synthetic polymer fiber
PA (0.4 mM, 1.5 denier) 15.9 μeq / g PAB (1.0 mM, 1.5 denier) 29.2 μeq / g Cellulose nanofibers 51.5 μeq / g

From the above analysis, it was confirmed that the PAB fiber has higher surface charge than the PA fiber, and the cellulose nanofiber has a very large surface charge.

500 mL of a 24 g / L cellulose nanofiber batch solution was diluted by adding it to 1500 mL of water. The diluted solution and the polyamide fibers were mixed in each ratio using a mixer (cellulose nanofibers: polyamide fibers (PA) = 10: 0 to 0:10). This mixture was dried in a convection oven at 80 ° C for 3 hours or more.

2 (a), 300 g / m ² , and 600 g / m ^2, respectively, of the composite sheet prepared above according to the respective ratios.

Subsequently, a nanofiber composite having a basis weight of 300 g / m ² and a weight of 600 g / m ² was prepared by pressurizing at 800 ° C. at 180 ° C. using a calender.

As a result, when the ratio of cellulose nanofibers to PA is 1: 9, the cellulose nanofibers are separated from each other by the difference in density between cellulose nanofibers and PA, 5, it was found that the drainage was not good and the curling after drying was the most serious. In addition, the morphology stability of the 600 g / m ² composite sheet from 300 g / m ² was good, but it was found that more time was required for drying.

That is, it was confirmed through this experimental example that good dispersibility and workability are exhibited when the ratio of cellulose nanofibers to PA is 2: 8, 3: 7, 4: 6 and the basis weight is 300 g / m ² .

Example 3: Cellulose nanofibers / thermoplastic synthetic polymeric composite sheets and nanofibers through a wet nonwoven process Composite  Produce

The cellulose nano fiber / thermoplastic synthetic polymer fiber composite sheet was produced by the method of Example 2 using PA and PAB synthetic fibers. The ratio of cellulose nanofiber to synthetic fiber was determined to be 2: 8, 3: 7, 4: 6, and the basis weight was determined to be 300 g / m < ² >

A photograph of the composite sheet after drying is shown in Fig. It was confirmed that PAB fiber showed better morphological stability than PA fiber and curling phenomenon after drying. This indicates that the PAB has a longer fiber length than PA, which is difficult to mix and disperse with water, but increases the morphological stability due to bonding between fibers.

Thereafter, the cellulose nanofiber composite was prepared by the same calendering process as in Example 2.

The tensile properties of each of the prepared cellulose nano-fiber composites were measured and shown in FIG. 3B. As a result, the mechanical properties of tensile strength and tensile elastic modulus increased with increasing cellulose nano fiber content. In particular, cellulose nanofiber composites with a ratio of cellulose nanofibers to thermoplastic synthetic polymer fibers of 4: 6 showed the best properties, and PAB nanofiber composites showed higher strength and elastic modulus than PA nanofiber composites.

In addition, the morphological characteristics were analyzed by SEM photograph of the surface and fracture surface of each nanofiber composite, and it is shown in FIG. 3c. As a result, it was confirmed that the pore between the fiber and the fiber was filled with the cellulose nanofiber. As the content of the cellulose nanofiber increased, the pore size tended to decrease.

Example 4 Cellulose Nanofibers / Thermoplastic Synthetic Polymer Fiber Composite Sheets and Nanofibers Through a Wet Nonwoven Process Including a Wet Prssing Process Composite  Produce

According to the manufacturing method of Example 2, a cellulose nano-fiber / thermoplastic synthetic polymer fiber composite sheet having a basis weight of 300 g / m ² was prepared by setting the weight ratio of the PAB fiber and the cellulose nano fiber to 6: 4. Unlike Example 2, however, they were pressurized at 80 DEG C, 5, 200, and 400 kg / cm < ² > for 2 hours using a hot press in a wet state before drying. This wet pressing in the wet state prevents curling of the produced sheet and increases the density of the composite sheet. After drying in a convection oven at 80 ° C for more than 2 hours, the final nanofiber composite was prepared by pressurizing at 800 ° C at 180 ° C using a calender. Table 2 shows the density of each cellulose nanofiber composite according to the pressure applied during wet pressing. As a result, the density increased as the pressure increased. This increase in density is due to the decrease in pore and volume between the cellulose nanofibers and the synthetic polymer fibers as the pressure increases. This increase in density can improve the mechanical and thermal properties of composites.

Pressure (kg / cm ² ) Density (g / m ³ ) 0 0.25 5 0.33 200 0.64 400 0.73

Example  5: Cationic Polyacrylamide  Including cellulose nano-fiber / thermoplastic synthetic polymer fiber composite sheet and nanofiber Of composites  Produce

According to the manufacturing method of Example 3, cationic polyacrylamide (c-PAM) was added to the cellulose nano-fiber / thermoplastic synthetic polymer fiber composite sheet at a ratio of 3: 7 and 5: 5 to prepare a composite sheet Respectively. At this time, retention values of cellulose nanofibers were measured by setting the concentrations of c-PAM to 0, 0.1, 0.15 and 0.2 wt%, respectively. The total fiber solid concentration at the time of dispersion in water was 2.5 g / 500 ml. The measurement results are shown in Table 3 below.

Retention (% by weight) Cellulose nanofiber retention [wt%] c-PAM addition amount [wt%] 0 0.1 0.15 0.2 Cellulose nanofibers / PA (0:10) - - - - Cellulose nanofibers / PA (5: 5) 54 79 90 90 Cellulose nanofibers / PA (3: 7) 50 85 89 88 Cellulose nanofibers / PAB (5: 5) 52 76 83 90 Cellulose nanofibers / PAB (3: 7) 40 76 83 90

From this, it can be seen that the retention value is the highest when the concentration of c-PAM is 0.2 wt%.

On the basis of the addition amount of this condition, 0.2 weight% of c-PAM was added to the cellulose nano fiber ratio in mixing thermoplastic synthetic polymer fibers to prepare a composite sheet. FIG. 4A is a photograph before and after drying of the composite sheet by the above production. As a result, the cellulose nano-fiber / thermoplastic synthetic polymer fiber composite sheet into which c-PAM is incorporated exhibits more curling after drying, and the result of the cellulose nano-fiber / thermoplastic synthetic polymer fiber composite sheet without c- On the other hand, it was confirmed that the curling of the PAB composite sheet is more marked than that of the PA composite sheet.

The composite sheet with c-PAM added as described above was subjected to the calendering process of Example 2 to prepare a nanofiber composite. The tensile strength and tensile elastic modulus of the composite sheet were measured and shown in FIG. 4B. As a result, it was confirmed that the tensile strength and tensile elastic modulus of the nanofiber composite increased when c-PAM was contained.

Example  6: Analysis of thermal expansion coefficient according to the ratio of cellulose nano fiber to synthetic fiber

In order to investigate the change of the thermal properties depending on the mixing ratio of the cellulose nanofiber and the synthetic fiber, the thermal expansion coefficient was measured by thermal deformation analysis with different ratios of the cellulose nanofiber and the PA / PAB fiber, . As shown in the following Table 4, it was found that the thermal expansion coefficient measured by thermal deformation analysis decreased sharply as the amount of cellulose increased.

Composition ratio Thermal Expansion Coefficient [ppm K ^-1 ] Cellulose nanofibers / PA (0:10) 75 Cellulose nanofibers / PA (3: 7) 20.3 Cellulose nanofibers / PA (5: 5) 13.6 Cellulose nanofibers / PAB (3: 7) 19.7 Cellulose nanofibers / PAB (5: 5) 12.3

Example  7: Cellulose nanofibers Of composites  Molding experiment by heat

According to the manufacturing method of Example 4, a cellulose nano fiber / thermoplastic synthetic polymer fiber composite sheet having a weight ratio of PAB fiber and cellulose nano fiber of 6: 4 and a basis weight of 150 g / m ² was produced. In wet condition before drying, it was pressurized by hot press at 80 ° C and 400 kg / cm ² pressure for 2 hours and then dried in convection oven at 80 ° C for 2 hours or more. Thereafter, the mixture was pressurized to 800 psi at 180 DEG C using a calender to prepare a nanofiber composite.

In order to confirm the thermal formation of the cellulose nano fiber composite, the composite was thermoformed. For this purpose, a tube-shaped mold with an outer diameter of 30 mm and a length of 400 mm and a cylinder bladder were used.

At this time, the temperature of the mold was 250 ° C. and the silicone bladder was heated and pressurized to 6 kg / cm ² . The mold used and the image of the tube thus prepared are shown in Fig. As a result, it was confirmed that the nanofiber composite of the present invention can be shaped to have various shapes by heat.

Claims (9)

1) preparing a cellulose nanofiber having an average diameter of 30 nm to 70 nm through a microfibrillation process;
2) preparing a dispersion by dispersing the cellulose nanofibers and the thermoplastic synthetic polymer fibers prepared in the step 1) in water;
3) preparing and drying a sheet-like nanocomposite through a wet nonwoven process using the dispersion of step 2);
4) applying a pressure of 2 MPa to 300 MPa at a temperature of 150 ° C to 250 ° C to the sheet-type nanocomposite of step 3) to melt the synthetic polymer fibers to form a matrix of a composite structure
A method for producing a thermoplastic nanocomposite reinforced with cellulose nanofibers.
The method of claim 1, wherein the thermoplastic synthetic polymer fiber of step 2) is a polyamide.
The method according to claim 2, wherein the fiber length of the polyamide is 0.4 mm to 1.0 mm.
The method of claim 1, wherein the weight ratio of the cellulose nanofibers to the thermoplastic synthetic polymer fibers in the dispersion of step 2) is from 2: 8 to 4: 6.
The method of claim 1, wherein the dispersion of step 2) further comprises a cationic polymer.
6. The composition of claim 5, wherein the cationic polymer is selected from the group consisting of cationic polyacrylamide, polyethyleneimine, anionic starch, poly (diallylmethylammonium chloride), dialkylaminoalkyl (meth) Alkyl (meth) acrylates, and copolymers of nonionic ethylenically unsaturated water-soluble monomers and monoethylenically unsaturated cationic monomers.
6. The method according to claim 5, wherein the concentration of the cationic polymer is 0.1 wt% to 0.3 wt%.
The method according to claim 1, comprising compressing by wet-pressing between the production and drying of the sheet-like nanocomposite of step 3).
The method according to claim 1, wherein the drying in step 3) is carried out at a room temperature to 80 ° C for 3 to 24 hours.

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