KR102209966B1 - Polyamide composite materials containing nanochitosan fiber in acqueous solution and method for preparing the same - Google Patents

Abstract

The present invention relates to nanochitosan fibers dispersed in an aqueous solution, a polyamide polymerization composition comprising the same, a polyamide composite material prepared by polymerizing the same, and a method for preparing the same. More specifically, the present invention can provide a polyamide polymerization composition in which nanochitosan fibers are dispersed in an aqueous solution, and improve mechanical properties such as tensile strength of the composite material prepared by polymerization thereof. Accordingly, the present invention provides a new polyamide composite material, in which nanochitosan fibers are dispersed, and which has remarkable mechanical properties, and a method for preparing the same.

Description

Nanochitosan fiber dispersed in aqueous solution, polyamide composite material containing the same, and manufacturing method thereof {POLYAMIDE COMPOSITE MATERIALS CONTAINING NANOCHITOSAN FIBER IN ACQUEOUS SOLUTION AND METHOD FOR PREPARING THE SAME}

The present invention relates to a novel nano-chitosan-polyamide composite material having remarkably improved mechanical properties compared to the polyamide composite material in which nano-chitosan fibers are dispersed, prepared by solution casting or melt-kneading, and a manufacturing method thereof. More specifically, a new composite material capable of improving mechanical properties such as tensile strength by interfacial polymerization of an aqueous solution in which nanochitosan fibers and a diamine-based compound are dispersed and an organic solution in which a dicarboxylic acid-based compound is dispersed, and a method for manufacturing the same. About.

The polyamide composite material is manufactured into a film through a solution casting method as in Korean Patent Registration No. 10-0375244. When manufacturing a composite material, a composite material manufactured by simply mixing polyamide and fiber or filler in an organic solvent and casting a solution has a limit in improving mechanical properties. Therefore, there is a need to develop a method for manufacturing a polyamide composite material that can significantly increase mechanical properties.

Republic of Korea Patent Publication No. 10-0375244 (2003.02.25.)

Conventionally, a polyamide composite material prepared by a solution casting method by mixing polyamide and a reinforcing agent such as fiber or filler in an organic solvent has limitations in mechanical properties. Therefore, in order to overcome these limitations of mechanical properties, the present inventors have interfacially polymerized an aqueous phase in which nanochitosan fibers are dispersed together with a diamine compound and an organic solution phase in which a dicarboxylic acid-based compound is dispersed during polyamide polymerization. A polyamide composite material was prepared. As a result, nanochitosan having hydrophilic groups -OH and -NH ₂ is evenly dispersed in the aqueous solution, and the dispersibility is improved than that of the composite material produced by the conventional solution casting method, thereby remarkably increasing mechanical properties such as tensile strength. It was found that the present invention was completed.

That is, the present invention is a novel nano-chitosan-polyamide composite material with remarkably improved mechanical properties by interfacial polymerization of an aqueous solution in which nanochitosan fibers and a diamine compound are dispersed, and an organic solution phase in which a dicarboxylic acid-based compound is dispersed. It is an object to provide a method and a molded article produced therefrom.

One aspect of the present invention for achieving the above object

a) preparing an aqueous dispersion containing nanochitosan fibers, a diamine-based compound, and a basic compound;

b) interfacial polymerization of the aqueous dispersion and an organic solution including a dicarboxylic acid compound to prepare a polyamide resin in which nanochitosan is dispersed;

It is to provide a method for producing a polyamide composite material comprising a.

Another aspect of the present invention,

As a molded article manufactured by molding a polyamide composite material prepared by interfacial polymerization of the nanochitosan fiber and an aqueous solution in which a diamine-based compound is dispersed and an organic solution in which a dicarboxylic acid-based compound is dispersed,

The molded article is to provide a molded article whose tensile strength according to ASTM D638 satisfies Equation 1 below.

[Equation 1]

In Formula 1,

TS ₀ is the tensile strength (MPa) of a molded article formed of a polyamide composite material containing nanochitosan prepared by a solution casting method, and TS ₁ is an aqueous solution in which nanochitosan fibers and diamine compounds are dispersed It is the tensile strength (MPa) of a molded article obtained by molding a polyamide composite material prepared by interfacial polymerization of an organic solution phase in which an acid-based compound is dispersed.

In one aspect of the present invention, the polyamide composite material prepared from the monomer stage by dispersing nanochitosan fibers in an aqueous solution is prepared by solution casting by dispersing a polyamide polymer and nanochitosan fibers in a conventional organic solvent. Mechanical properties such as tensile strength are significantly better than composite materials.

Hereinafter, the present invention will be described in more detail through specific examples or examples including the accompanying drawings. However, the following examples are only a reference for describing the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

In addition, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. The terms used in the description herein are merely for effectively describing specific embodiments, and are not intended to limit the invention.

In the present invention, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

In addition, the singular form used in the specification and the appended claims may be intended to include the plural form unless otherwise indicated in the context.

Unless otherwise stated in the present specification, the term "dicarboxylic acid compound" used in the present invention is a dibasic acid having two carboxyl groups and includes dicarboxylate, dicarboxylic acid ester, and the like.

One aspect of the present invention for achieving the above object,

a) preparing an aqueous dispersion containing nanochitosan fibers, a diamine-based compound, and a basic compound;

b) interfacial polymerization of the aqueous dispersion and an organic solution including a dicarboxylic acid compound to prepare a polyamide resin in which nanochitosan is dispersed;

It is to provide a method for producing a polyamide composite material comprising a.

Another aspect of the present invention,

As a molded article manufactured by molding a polyamide composite material prepared by interfacial polymerization of an aqueous solution in which the nanochitosan fiber and a diamine compound are dispersed and an organic solution phase in which a dicarboxylic acid compound is dispersed,

The molded article is to provide a molded article whose tensile strength according to ASTM D638 satisfies Equation 1 below.

[Equation 1]

In Formula 1,

TS ₀ is the tensile strength (MPa) of a molded article formed of a polyamide composite material containing nanochitosan prepared by a solution casting method, and TS ₁ is an aqueous solution in which nanochitosan fibers and diamine compounds are dispersed It is the tensile strength (MPa) of a molded article obtained by molding a polyamide composite material prepared by interfacial polymerization of an organic solution phase in which an acid-based compound is dispersed.

In one aspect, the polyamide composite material prepared by interfacial polymerization between the nanochitosan fiber and an aqueous solution containing a diamine compound and an organic solution containing a dicarboxylic acid compound is a polyamide composite prepared by a solution casting method. Compared to the material, not only the dispersibility of the nanochitosan fiber is improved, but -NH ₂ on the surface of the nanochitosan fiber participates in polymerization and is chemically bonded to provide a composite material with improved mechanical properties.

In one aspect, the nanochitosan fibers may have an average diameter of 2 to 200 nm and a length of 50 nm to 10 μm, but are not limited thereto.

In one aspect, the polyamide resin may provide a method of manufacturing a polyamide composite material including the repeating unit of Formula 1 below.

[Formula 1]

(In Formula 1, A is selected from C1-C20 aliphatic hydrocarbons, and B is selected from C2-C20 aliphatic hydrocarbons.)

In one aspect, the polyamide composite material may have a tensile strength increase rate satisfying Equation 1 below.

[Equation 1]

In Formula 1,

TS ₀ is the tensile strength (MPa) of a polyamide composite material containing nanochitosan prepared by a solution casting method, and TS ₁ is an aqueous solution in which nanochitosan fibers and a diamine compound are dispersed, and a dicarboxylic acid compound is This is the tensile strength (MPa) of a polyamide composite material prepared by interfacial polymerization of a dispersed organic solution phase.

Another aspect of the present invention is a molded article manufactured by molding a polyamide composite material prepared by interfacial polymerization of an aqueous solution in which the nanochitosan fiber and a diamine compound are dispersed and an organic solution phase in which a dicarboxylic acid compound is dispersed,

The molded article may be a molded article whose tensile strength according to ASTM D638 satisfies Equation 1 below.

[Equation 1]

In Formula 1,

TS ₀ is the tensile strength (MPa) of a molded article formed of a polyamide composite material containing nanochitosan prepared by a solution casting method, and TS ₁ is an aqueous solution in which nanochitosan fibers and diamine compounds are dispersed It is the tensile strength (MPa) of a molded article obtained by molding a polyamide composite material prepared by interfacial polymerization of an organic solution phase in which an acid-based compound is dispersed.

In another aspect of the present invention, the size of the nanochitosan fibers may have an average diameter of 2 to 200 nm and a length of 50 nm to 10 μm, but is not limited thereto.

In another aspect of the present invention, the nanochitosan fiber may be included in an amount of 0.01 to 2 parts by weight based on 100 parts by weight of polyamide.

In another aspect of the present invention, the polyamide resin may include a repeating unit represented by the following formula (1).

[Formula 1]

(A is selected from C1-C20 aliphatic hydrocarbons, and B is selected from C2-C20 aliphatic hydrocarbons.)

Hereinafter, each configuration of the present invention will be described in more detail.

In one aspect of the present invention, the polyamide is not particularly limited, but refers to a generic term for a polymer linked by an amide bond, and may include a polyamide obtained by condensation polymerization of a diamine and a dicarboxylic acid compound. Preferably, it may be nylon 6,6 prepared by interfacial polymerization of adipic acid and hexamethylenediamine.

In the method of manufacturing a polyamide composite material according to an aspect of the present invention, step a) may be mixed and dispersed by adding nanochitosan fibers and a diamine-based compound in an aqueous solution, and the order of addition is irrelevant. If it is easy to mix and disperse the nanochitosan fibers in the aqueous solution, the mixing method is not particularly limited, but for example, a method such as ultrasonic dispersion may be used when mixing and dispersing in the aqueous solution in step a).

In addition, in step a), the nanochitosan fiber may contain 0.0001 to 10 parts by weight based on 100 parts by weight of the polyamide. Preferably, it may contain 0.01 to 3 parts by weight, more preferably 0.01 to 2 parts by weight, based on 100 parts by weight of the polyamide. When included in the above range, it may have excellent tensile strength.

The nanochitosan fibers in step a) are not particularly limited, but may have an average diameter of 2 to 200 nm, and more preferably 1 to 100 nm. In addition, it may be a fiber having a length of 50 nm to 100 µm, more preferably 100 nm to 10 µm. When the nano-chitosan fiber is included, the dispersibility is excellent, and accordingly, the mechanical properties of the polyamide composite material, in particular, the synergistic effect of the tensile strength are superior, and thus it is preferable.

In step b), the organic solvent may be used without particular limitation as long as it can dissolve the dicarboxylic acid-based compound. For example, 1,2-dichlorobenzene, hexane, pentane, cyclohexane, heptane, octane, carbon tetrachloride, benzene, toluene, dimethyl sulfoxide, dimethylacetamide, methylpyrrolidone, etc. may be used, but are limited thereto. It is not.

The dicarboxylic acid-based compound in step b) is not particularly limited, but may include at least one of an aromatic dicarboxylic acid having 8 to 20 carbon atoms and an aliphatic dicarboxylic acid having 3 to 20 carbon atoms. The aromatic dicarboxylic acid compound is, for example, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4 -Phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, diphenic acid, 4,4'-oxydibenzoic acid, diphenylmethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4 Aromatic dicarboxylic acid-based compounds such as'-dicarboxylic acid and 4,4'-biphenyldicarboxylic acid, and mixtures thereof may be used, but are not limited thereto.

The aliphatic dicarboxylic acid is, for example, maronic acid, dimethylmaronic acid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimeric acid, 2,2-dimethylglutalic acid, Aliphatic dicarboxylic acids such as 3,3-diethylsuccinic acid, sveric acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid, and 1,4-cyclohexanedicarboxylic acid, and 1,3-cyclopentane It may be an alicyclic dicarboxylic acid such as dicarboxylic acid, and the like, but is not limited thereto.

In one aspect of the present invention, after preparing the polyamide resin in which the nanochitosan prepared in step b) is dispersed, a process of preparing a molded body may be further included. More specifically, although not particularly limited, for example, it may be manufactured into a film through a casting process. The thickness of the film may be 10 to 500㎛, but is not limited thereto.

In one aspect of the present invention, the prepared polyamide composite material may have a tensile strength that satisfies Equation 1 below.

[Equation 1]

In Formula 1,

TS ₀ is the tensile strength (MPa) of a polyamide composite material containing nanochitosan prepared by a solution casting method, and TS ₁ is an aqueous solution in which nanochitosan fibers and a diamine compound are dispersed, and a dicarboxylic acid compound is This is the tensile strength (MPa) of a polyamide composite material prepared by interfacial polymerization of a dispersed organic solution phase.

Preferably, Equation 1 may satisfy 115% or more. Moreover, when prepared from a polyamide composite material prepared by interfacial polymerization of an aqueous solution in which nanochitosan fibers and a diamine-based compound are dispersed and an organic solution in which a dicarboxylic acid-based compound is dispersed, the above formula 1 is 120% or more, preferably It is more preferable because it can satisfy 140% or more. The upper limit is not particularly limited, but may preferably be 115 to 250%. In the case of manufacturing a composite material according to the manufacturing method of the present invention, the polyamide composite material of the present invention has excellent tensile strength as described above, even without the use of an excessive amount of nano-chitosan fibers compared to the conventional solution casting method using an organic solvent. You can secure an increase rate.

In one aspect of the present invention, the polyamide composite material not only can easily manufacture the composite material in the in-situ process as described above, but also the nanochitosan fibers are evenly distributed in the polyamide resin, Compared to the polyamide composite material produced by the solution casting method, mechanical strength such as tensile strength can be remarkably improved.

In one aspect of the present invention, a polyamide composite whose tensile strength is increased by crosslinking with a monomer during interfacial polymerization by dispersing the dispersed nanochitosan by dispersing it from the monomer stage in an aqueous solution rather than simply physically mixing the polyamide polymer and nanochitosan. Materials can be manufactured.

Another aspect of the present invention is a molded article manufactured by molding a polyamide composite material prepared by interfacial polymerization of an aqueous solution in which the nanochitosan fiber and a diamine compound are dispersed and an organic solution phase in which a dicarboxylic acid compound is dispersed,

The molded article may be a molded article whose tensile strength according to ASTM D638 satisfies Equation 1 below.

[Equation 1]

In Formula 1,

TS ₀ is the tensile strength (MPa) of a molded article formed of a polyamide composite material containing nanochitosan prepared by a solution casting method, and TS ₁ is an aqueous solution in which nanochitosan fibers and diamine compounds are dispersed It is the tensile strength (MPa) of a molded article obtained by molding a polyamide composite material prepared by interfacial polymerization of an organic solution phase in which an acid-based compound is dispersed.

In another aspect of the present invention, the size of the nano-chitosan fibers of the molded article may be a molded article having an average diameter of 2 to 200 nm and a length of 50 nm to 10 μm.

In another aspect of the present invention, the polyamide may include Formula 1 as follows, and is not particularly limited, but the polymer composition including the polyamide represented by Formula 1 below has tensile strength when prepared as a composite film Can be significantly improved.

[Formula 1]

(In Formula 1, A is selected from C1-C20 aliphatic hydrocarbons, and B is selected from C2-C20 aliphatic hydrocarbons.)

In another aspect of the present invention, the molded article is not particularly limited, for example, after interfacial polymerization of an aqueous solution in which nanochitosan fibers and a diamine-based compound are dispersed and an organic solution in which a dicarboxylic acid-based compound is dispersed. It can be dried as a solid sample and then again melt-extruded or injected into a molded body.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. However, the following Examples and Comparative Examples are only one example for describing the present invention in more detail, and the present invention is not limited by the following Examples and Comparative Examples.

[Method of measuring properties]

(1) Tensile strength

The prepared polyamide composite material was melt-injected in a dumbbell-shape of ASTM D638-Type 1 standard, and then tensile test was performed according to ASTM D638 using a universal testing machine (UTM 5942, INSTRON).

The tensile strength increase rate (MPa) was calculated as compared to the tensile strength of the polyamide composite material prepared by the solution casting method in each example through the following calculation formula 1.

[Calculation 1]

In Formula 1,

TS ₀ is the tensile strength (MPa) of a polyamide composite material containing nanochitosan prepared by a solution casting method, and TS ₁ is an aqueous solution in which nanochitosan fibers and a diamine compound are dispersed, and a dicarboxylic acid compound is This is the tensile strength (MPa) of a polyamide composite material prepared by interfacial polymerization of a dispersed organic solution phase.

[Synthesis Example 1]

To prepare an organic solution in which adipoyl chloride (6.18 g, 33.8 mmol) was dissolved in 200 ml of 1,2-dichlorobenzene, and hexamethylenediamine (4.31 g, 37.1 mmol) and NaOH (3.0 g, 75 mmol) in 400 ml of distilled water While the aqueous solution in which was dissolved was stirred vigorously, the organic solution was slowly added to the aqueous solution to polymerize nylon 66. Thereafter, the produced nylon 66 was washed several times with methanol, filtered, and vacuum dried at 80° C. for 12 hours. After that, it was cooled and pulverized in liquid nitrogen for 10 minutes and sonicated in methanol for 30 minutes. This process was repeated 3 times to remove impurities.

[Synthesis Example 2]

Shrimp shell-sourced α-chitin (Sigma Aldrich, USA) powder (5 g) was immersed in 3 M HCl aqueous solution (150 mL) and heated at 120° C. for 3 hours under a nitrogen atmosphere. The suspension was centrifuged for 10 minutes at 10,000 rpm. The supernatant was removed and the precipitate was redispersed in deionized water (DIW) (150 mL). The above acid dilution process was repeated 3 times. The suspension was then dialyzed with deionized water until the pH reached 7. Deionized water was added to adjust the concentration of the suspension to 1% by weight. The purified suspension was sonicated for 10 minutes with the same 750 W tip sonicator. An aqueous chitin nanowhisker (ChW) suspension was lyophilized.

The freeze-dried ChW (5g) was heated at 80° C. for 6 hours in 30 wt% NaOH aqueous solution (100g). When the pH of the suspension did not decrease, ethanol (EtOH) (10 ml) was added to terminate the reaction. The suspension was centrifuged for 10 minutes at 10,000 rpm. The supernatant was removed and the precipitate was redispersed in deionized water. The dilution process was repeated 3 times, and the suspension was dialyzed with deionized water until the pH reached 7. The purified suspension was sonicated for 10 minutes with the same tip sonicator, and the suspension was freeze-dried to obtain nanochitosan fibers in powder form. (The average particle diameter of nanochitosan fibers is 12 nm, length 180 nm)

[Example 1]

In the polyamide composite material prepared by the in-situ method, the nanochitosan fiber prepared in Synthesis Example 2 was first added to a solution of (A) 400 ml of distilled water and hexamethylenediamine (4.31 g, 37.1 mmol), and the theoretical polymer yield was 100 weight. It was added and dispersed in 0.1 parts by weight of comparison. Thereafter, (B) adifoyl chloride (6.18 g, 33.8 mmol) was dispersed in 200 ml of 1,2-dichlorobenzene, an organic solvent layer, and then slowly added to the solution (A), the resulting nylon 66 was washed several times with methanol and filtered. Vacuum-dried at 80° C. for 12 hours. After that, it was cooled and pulverized in liquid nitrogen for 10 minutes and sonicated in methanol for 30 minutes. This process was repeated 3 times to remove impurities.

In addition, in order to determine the rate of increase in tensile strength, a composite film was prepared using the solution casting method compared to the film produced by the in-situ method of the present invention, and the tensile strength of the composite film prepared by the solution casting method was 65 MPa.

Therefore, as shown in Table 1, when the polyamide composite material is manufactured by the in-situ method of the present invention, the increase rate of tensile strength is 117%, and it can be seen that it has a remarkable increase rate of tensile strength.

[Example 2]

In Example 1, a comparative composite film was prepared using solution casting in the same procedure as in Example 1, except that 0.2 parts by weight of nanochitosan fibers were added to 100 parts by weight of the theoretical polyamide polymer yield. As shown in Table 1, the increase rate of physical properties was measured.

[Example 3]

In Example 1, it was carried out in the same manner, except that the nanochitosan fiber was added in an amount of 0.3 parts by weight based on 100 parts by weight of the theoretical polyamide polymer yield.

[Example 4]

In Example 1, the same was carried out except that the nanochitosan fiber was added in an amount of 0.4 parts by weight based on 100 parts by weight of the theoretical polyamide polymer yield.

[Comparative Example 1]

The polyamide comparative composite film using the solution casting method dissolves 6.5 parts by weight of the polyamide synthesized in Synthesis Example 1 in an organic solvent relative to 100 parts by weight of an organic solvent (meta-cresol), and has an average diameter of 15 nm and an average length. A solution was prepared by adding 0.3 parts by weight of nanochitosan fibers having 200 nm by weight to 100 parts by weight of the theoretical yield of polyamide. The solution was sonicated for 2 hours to uniformly disperse the nanochitosan fibers. Thereafter, the solution was allowed to stand for 24 hours, and then the solution was dispersed by ultrasonic treatment for 2 hours. To obtain a film, the solution was poured into a glass Petri dish (15 mL, per petri dish with diameter of 90 mm = 63.6 ㎠) and the solvent was evaporated for 5 days. Made it. Thereafter, vacuum drying was performed at 80° C. for 24 hours to remove residual solvent to prepare a polyamide composite film.

content The tensile strength
(MPa) Tensile strength increase rate
(%) Synthesis Example 1 - 61 - Example 1 0.1 76 117 Example 2 0.2 78 120 Example 3 0.3 97 149 Example 4 0.4 106 163 Comparative Example 1 0.3 65 -

As shown in Table 1, it can be seen that the polyamide composite film prepared by the in-situ method according to the present invention has a remarkably increased tensile strength compared to the polyamide composite film of Comparative Example 1 prepared by the solution casting method. there was.

Moreover, when the content of nanochitosan was included in an amount of 0.1 to 0.4 parts by weight relative to 100 parts by weight of polyamide, it was confirmed that more excellent mechanical properties synergistic effect could be realized.

The present invention described above is merely exemplary, and those of ordinary skill in the art to which the present invention pertains will appreciate that various modifications and other equivalent embodiments are possible. Therefore, it will be appreciated that the present invention is not limited to the form mentioned in the detailed description above. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

Therefore, the spirit of the present invention is limited to the described embodiments and should not be defined, and all things that are equivalent or equivalent to the claims as well as the claims to be described later fall within the scope of the spirit of the present invention. .

Claims (10)

a) preparing an aqueous dispersion containing nanochitosan fibers having an average diameter of 2 to 200 nm, a diamine-based compound, and a basic compound;
b) interfacial polymerization of the aqueous dispersion and an organic solution including a dicarboxylic acid compound to prepare a polyamide resin in which nanochitosan is dispersed;
Method for producing a polyamide composite material comprising a. The method of claim 1,
A method for producing a polyamide composite material comprising the step of molding a polyamide resin in which the nanochitosan prepared in step b) is dispersed. The method of claim 1,
The method of manufacturing a polyamide composite material having a length of the nanochitosan fibers of 50 nm to 10 μm. The method of claim 1,
The method for producing a polyamide composite material, wherein the nanochitosan fibers are contained in an amount of 0.01 to 2 parts by weight based on 100 parts by weight of polyamide. The method of claim 1,
The polyamide resin is a method for producing a polyamide composite material comprising a repeating unit represented by the following formula (1).
[Formula 1]

(In Formula 1, A is selected from C1-C20 aliphatic hydrocarbons, and B is selected from C2-C20 aliphatic hydrocarbons.) As a molded article manufactured by molding a polyamide composite material prepared by interfacial polymerization of a nanochitosan fiber having an average diameter of 2 to 200 nm, an aqueous solution in which a diamine compound is dispersed, and an organic solution phase in which a dicarboxylic acid compound is dispersed,
The molded article has a tensile strength according to ASTM D638 that satisfies Equation 1 below.
[Equation 1]

In Formula 1,
TS ₀ is the tensile strength (MPa) of a molded article formed of a polyamide composite material containing nanochitosan prepared by a solution casting method, and TS ₁ is an aqueous solution in which nanochitosan fibers and diamine compounds are dispersed It is the tensile strength (MPa) of a molded article obtained by molding a polyamide composite material prepared by interfacial polymerization of an organic solution phase in which an acid-based compound is dispersed. The method of claim 6,
A molded article having a length of the nanochitosan fibers of the molded article 50 nm to 10 μm. The method of claim 6,
The polyamide resin of the molded article comprises a repeating unit represented by the following formula (1).
[Formula 1]

(A is selected from C1-C20 aliphatic hydrocarbons, and B is selected from C2-C20 aliphatic hydrocarbons.) The method of claim 6,
The nano-chitosan fiber of the molded article is a molded article comprising 0.01 to 2 parts by weight based on 100 parts by weight of polyamide. The method of claim 6,
The molded article is a molded article manufactured by melt extrusion or injection again after preparing a polyamide composite material by introducing nanochitosan in an aqueous solution of a diamine compound.