KR102260166B1 - Method for preparing biodegradable composite material and the biodegradable composite material manufactured therefrom - Google Patents

Abstract

The present invention relates to: a) an aliphatic dicarboxylic acid; aliphatic diols; and at least one natural polymer nanofiber selected from nanochitin fibers and nanocellulose fibers; mixing and dispersing to prepare a dispersion; and b) adding polybutylene terephthalate to the dispersion, mixing and dispersing to polymerize It relates to a method for manufacturing a biodegradable composite material comprising the step of, and to a biodegradable composite material prepared therefrom.

Description

Method for manufacturing biodegradable composite material and biodegradable composite material manufactured therefrom { METHOD FOR PREPARING BIODEGRADABLE COMPOSITE MATERIAL AND THE BIODEGRADABLE COMPOSITE MATERIAL MANUFACTURED THEREFROM}

The present invention relates to a method for manufacturing a biodegradable composite material and a biodegradable composite material prepared therefrom.

Recently, as the issue of plastic waste grows, the development of biodegradable materials is attracting attention. Among them, a new eco-friendly material that can replace existing petroleum-based polymers with biodegradable polymers is highlighted, and various R&Ds have been made and applied in the market.

As a representative example of the biodegradable polymer, polybutylene succinate (PBS) is widely used. However, the polybutylsuccinic acid by itself does not have sufficient mechanical properties, so many researchers are actively conducting research and development to make a composite and make a material with improved mechanical properties while having biodegradability.

In the past, the composite was provided by mixing a biodegradable polymer and inorganic materials such as carbon-based and ceramic-based materials, but the inorganic materials do not have biodegradable particles themselves, so non-degradable products are generated and fine dust is generated during incineration. there was

Due to such problems, research and development is being attempted to provide a composite by mixing a biodegradable organic material rather than an inorganic material with a biodegradable polymer.

The organic materials as described above cause aggregation in the biodegradable polymer and have difficulty in uniform dispersion, so a method for increasing their miscibility is absolutely necessary. Therefore, conventionally, as a method of increasing the miscibility, a method of modifying the surface of an organic material, a method of mixing a biodegradable polymer in a molten state, and a method of mixing with a solution using an organic solvent have been tried.

However, the method of modifying the surface as described above causes excessive cost from an industrial point of view, a problem in that production time is delayed, and a problem in that the mechanical reinforcement effect of the organic material is significantly reduced.

In addition, in the method of mixing the biodegradable polymer and the molten state, the biodegradable polymer has a high viscosity in the molten state and low miscibility with the organic material, thereby exposing it to a high temperature for a long time, causing thermal decomposition of the organic material.

In addition, the method of mixing the biodegradable polymer and the organic solvent in solution has a problem in that the dispersibility of the organic material is reduced and environmental pollution is caused.

Accordingly, there is a need for a method for manufacturing a biodegradable composite material capable of uniformly dispersing an organic material in a biodegradable polymer and remarkably increasing mechanical properties.

An object of the present invention for solving the above problems is to provide a method for producing a biodegradable composite material that induces uniform dispersion of natural polymer nanofibers in a biodegradable polymer without a pretreatment process such as surface hydrophobization.

In addition, another object of the present invention is to provide a method for producing a biodegradable composite material that realizes a significant increase in mechanical properties compared to a biodegradable material that does not contain natural polymer nanofibers, and a biodegradable composite material prepared therefrom. .

As a result of research to achieve the above object, the method for preparing a biodegradable composite material according to the present invention is a) an aliphatic dicarboxylic acid; aliphatic diols; and at least one natural polymer nanofiber selected from nanochitin fibers and nanocellulose fibers; mixing and dispersing to prepare a dispersion; and b) adding polybutylene terephthalate to the dispersion, mixing and dispersing to polymerize including the steps of

The biodegradable composite material according to an aspect of the present invention may be one in which natural polymer nanofibers are formed as a crosslinker of a polymer derived from polybutylene terephthalate, aliphatic dicarboxylic acid and aliphatic diol.

The molar ratio of terephthalate in the aliphatic dicarboxylic acid and polybutylene terephthalate according to an embodiment of the present invention may be 10:90 to 90:10.

The natural polymer nanofibers according to an aspect of the present invention may include 0.001 to 3% by weight based on the total weight of the biodegradable composite material.

The natural polymer nanofibers according to an aspect of the present invention may have an average diameter of 2 to 200 nm, and a longest length of 100 nm to 10 μm.

Another aspect of the present invention is polybutylene terephthalate; aliphatic dicarboxylic acids; aliphatic diols; It is a biodegradable composite material derived by polymerizing a dispersion comprising; and a natural polymer nanofiber at least one selected from nanochitin fibers and nanocellulose fibers.

The polybutylene terephthalate according to an aspect of the present invention may have a weight average molecular weight of 10,000 to 100,000 g/mol.

The natural polymer nanofiber according to an aspect of the present invention may be formed of a crosslinker of a polymer derived from polybutylene terephthalate, aliphatic dicarboxylic acid and aliphatic diol.

The biodegradable composite material according to an aspect of the present invention may have a tensile strength satisfying Equation 1 below.

[Equation 1]

In the above formula 1,

TS ₀ is the tensile strength (MPa) of the biodegradable material that does not contain natural polymer nanofibers, and TS ₁ is the tensile strength (MPa) of the biodegradable composite material.

The biodegradable composite material according to an aspect of the present invention may have a tear strength satisfying the following formula (2).

[Equation 2]

In Equation 2,

The TR ₀ is the tearing strength (kgf/cm) of the biodegradable material that does not contain natural polymer nanofibers, and the TR ₁ is the tearing strength (kgf/cm) of the biodegradable composite material.

The method of manufacturing a biodegradable composite material according to the present invention has the advantage of having a synergistic effect of excellent mechanical properties through uniform complexation of biodegradable polymers and natural polymer nanofibers without a pretreatment process that causes cost increase and productivity decrease.

In addition, the biodegradable composite material according to the present invention has an advantage in that it not only has excellent tensile strength, but also has a significantly higher tensile elongation and an increase in tear strength compared to a biodegradable material that does not contain natural polymer nanofibers.

1 shows the dispersibility of nanocellulose fibers (left) and nanochitin fibers (right) in adipic acid and 1,4-butanediol solutions in an embodiment of the present invention.
Figure 2 shows the dispersibility of nanocellulose fibers (left) and nanochitin fibers (right) in dimethyl terephthalate, adipic acid and 1,4-butanediol solutions in a comparative example of the present invention.

Hereinafter, the method for producing a biodegradable composite material according to the present invention and the biodegradable composite material prepared therefrom will be described in more detail through Examples. 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.

Also, unless defined otherwise, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description herein is for the purpose of effectively describing particular embodiments only, and is not intended to limit the invention.

The present invention for achieving the above object relates to a method for producing a biodegradable composite material and a biodegradable composite material prepared therefrom.

In the conventional method, it was difficult to homogeneously disperse organic materials such as natural polymer nanofibers in biodegradable polymers. Moreover, any one or more natural polymer nanofibers selected from the nanochitin fibers and nanocellulose fibers are hydrophilic components having a hydroxyl group (-OH) on the surface, and have low miscibility that is difficult to uniformly disperse in hydrophobic polybutylene terephthalate. Therefore, it was not easy to manufacture as a composite material. Accordingly, the present inventors have completed the present invention by discovering a method for manufacturing a composite material that can implement a synergistic effect of a higher level of mechanical properties compared to the existing biodegradable composite material.

The present invention will be described in detail as follows.

The method for producing a biodegradable composite material according to the present invention comprises: a) an aliphatic dicarboxylic acid; aliphatic diols; and at least one natural polymer nanofiber selected from nanochitin fibers and nanocellulose fibers; mixing and dispersing to prepare a dispersion; and b) adding polybutylene terephthalate to the dispersion, mixing and dispersing to polymerize including the steps of

The method for producing a biodegradable composite material according to the present invention comprises: an aliphatic dicarboxylic acid; aliphatic diols; And nanochitin fibers and at least one natural polymer nanofibers selected from nanocellulose fibers; After mixing and dispersing to prepare a dispersion, polybutylene terephthalate is added and polymerized, so that it is superior to existing biodegradable materials It is possible to significantly improve tensile strength, tensile elongation and tear strength while implementing acidity and miscibility.

On the other hand, when polybutylene terephthalate monomers, aliphatic dicarboxylic acid, aliphatic diol and aromatic dicarboxylic acid, and natural polymer nanofibers are linearly dispersed and then polymerized, aromatic dicarboxylic acid causes side reactions in the dispersion. induced, and causes precipitation of natural polymer nanofibers, and thus the dispersibility is lowered, so that the improvement of mechanical properties is minimal.

According to one aspect of the present invention, the biodegradable composite material is prepared as described above, whereby the natural polymer nanofiber is a crosslinker of a polymer derived from polybutylene terephthalate, aliphatic dicarboxylic acid and aliphatic diol. may be formed with For example, any one or two or more functional groups selected from hydroxyl groups (-OH) and salts thereof present in the natural polymer nanofiber may serve as a monomer. Accordingly, natural polymer nanofibers are dispersed in the polymer and exist in a dispersed phase, and a reaction with the residual groups of the polymer is induced to form a cross-linked structure of various shapes. can form.

By forming the structure as described above, natural polymer nanofibers are present in the biodegradable composite material with excellent dispersibility, and remarkably excellent mechanical properties can be achieved while preventing rapid deterioration of properties. These include aliphatic dicarboxylic acids; aliphatic diols; And nano-chitin fibers and at least one natural polymer nanofibers selected from nanocellulose fibers; after mixing and dispersing to prepare a dispersion, polybutylene terephthalate is added and polymerized, which can be achieved.

That is, the above-described effect of the biodegradable composite material of the present invention cannot be achieved by simply physically mixing polybutylene terephthalate and natural polymer nanofibers. In this case, as can be seen in Comparative Examples to be described later, there is a problem in that the improvement of mechanical properties is very weak or may be lowered on the contrary.

The method for producing a biodegradable composite material according to the present invention comprises: a) an aliphatic dicarboxylic acid; aliphatic diols; And to perform the step of preparing a dispersion by mixing and dispersing; and at least one natural polymer nanofiber selected from nanochitin fibers and nanocellulose fibers.

As described above, in the absence of aromatic dicarboxylic acid and its derivatives, specifically terephthalic acid and its derivatives, one or more natural polymer nanofibers selected from nanochitin fibers and nanocellulose fibers are mixed with aliphatic dicarboxylic acids and aliphatic diols. and dispersing to prepare a dispersion. By performing such a step, miscibility with polybutylene terephthalate can be further improved.

Thereafter, when polybutylene terephthalate in a polymer state is added to the dispersion, side reactions do not occur substantially and the natural polymer nanofibers can be homogeneously dispersed.

According to an aspect of the present invention, the natural polymer nanofibers are at least one selected from nanochitin fibers and nanocellulose fibers, and may preferably include nanochitin fibers or nanocellulose fibers.

The natural polymer nanofibers may be prepared from chitin or cellulose, which are natural polymer materials present in nature. Specifically, it refers to nanometer-sized rod-shaped particles or fibers in which cellulose or chitin chains are bundled together. In addition, it may be prepared by nanofiberizing chitin or cellulose by physical and chemical methods already known in the art.

According to an aspect of the present invention, the natural polymer nanofibers may have an average diameter of 2 to 200 nm, and a longest length of 100 nm to 10 μm. Preferably, the average diameter may be 2 to 100 nm, the longest length may be 100 nm to 5 μm, more preferably, the average diameter may be 2 to 100 nm, and the longest length may be 100 to 900 nm. When the natural polymer nanofibers as described above are included, the synergistic effect of mechanical properties, in particular, tensile strength, tensile elongation and tearing strength is superior.

On the other hand, if the average diameter of the natural polymer nanofibers exceeds the above range, for example, if it has a micrometer unit, even if the biodegradable composite material is manufactured by the same manufacturing method according to the present invention, the same effect cannot be achieved. . Rather, the improvement in dispersibility is insignificant, and it is difficult to achieve uniform physical properties due to the occurrence of precipitation, which may cause deterioration of mechanical properties.

According to an aspect of the present invention, the natural polymer nanofibers may include 0.001 to 3% by weight based on the total weight of the biodegradable composite material. Preferably it may contain 0.01 to 2% by weight, more preferably 0.01 to 1% by weight. When included in the above range, despite the small amount of natural polymer nanofibers contained in the biodegradable composite material, it has excellent tensile strength, and it is possible to significantly improve tensile elongation and tear strength at the same time.

According to an aspect of the present invention, the aliphatic dicarboxylic acid is not particularly limited, and specifically, it may be any one or more selected from aliphatic dicarboxylic acids and derivatives thereof. For example, it may be any one or more selected from oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, server acid, azelaic acid, and sebacic acid.

According to an aspect of the present invention, the aliphatic diol is not particularly limited, and specifically, it may be any one or more selected from aliphatic diols and derivatives thereof. For example, ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,4 -Dimethyl-2-ethyl-1,3-hexanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl It may be any one or more selected from -1,3-propanediol and 2,2,4-trimethyl-1,6-hexanediol.

As such, since the dispersion in step a) does not contain aromatic dicarboxylic acids and derivatives thereof, but contains aliphatic dicarboxylic acids and aliphatic diols, side reactions due to the presence thereof are suppressed to provide high molecular weight. and can minimize the generation of volatile organic compounds.

According to an aspect of the present invention, the aliphatic dicarboxylic acid and the aliphatic diol may be included in a molar ratio of 1:1 to 1:3. Preferably 1:1 to 1:2.5 molar ratio, more preferably 1:1 to 1:2 molar ratio may be included. When included in the above range, dispersibility can be further improved when combined with natural polymer nanofibers, and better mechanical properties can be achieved.

Next, in the method for producing a biodegradable composite material according to the present invention, b) polybutylene terephthalate is added to the dispersion, mixed and dispersed to perform polymerization. As described above, by linearly dispersing the natural polymer nanofibers including the aliphatic dicarboxylic acid and the aliphatic diol and then further dispersing polybutylene terephthalate, uniform miscibility can be realized and a remarkable increase rate of mechanical properties can be realized. .

According to an aspect of the present invention, the molar ratio of the terephthalate unit in the aliphatic dicarboxylic acid and polybutylene terephthalate may be 10:90 to 90:10. Preferably, the molar ratio of terephthalate in the aliphatic dicarboxylic acid and polybutylene terephthalate may be 10:90 to 60:40, and more preferably, the molar ratio may be 20:80 to 60:40. When included in the above range, excellent tensile strength, tensile elongation and tear strength can be remarkably improved.

According to an aspect of the present invention, step b) is not particularly limited as long as the reaction conditions and reaction equipment capable of inducing the transesterification reaction are not particularly limited, but specifically, in terms of inducing a high molecular weight, for example, 150 to At a temperature of 260° C., polymerization may be performed for 1 to 20 hours at a pressure of 0.001 to 500 Torr, but is not limited thereto. As another example, in terms of preventing the discoloration of the biodegradable composite material and providing a transparent product of excellent quality, polymerization may be performed for 1 to 15 hours at a temperature of 200 to 250° C. and at a pressure of 0.001 to 100 Torr. , but is not limited thereto.

According to an aspect of the present invention, in step b), the reaction apparatus may be a polymerization apparatus in which a reaction tank, a condenser, and a vacuum pressure reducing apparatus are connected, for example, in order to obtain a high molecular weight biodegradable composite material. Preferably, it may be a twin screw kneader type polymerization apparatus. When the polymerization apparatus is used, compared to using a general stirrer, it provides a large surface area during polymerization to shorten the polymerization time, obtain a high molecular weight, and improve the removal efficiency of by-products. In addition, it is possible to realize a significant increase in tensile strength, tensile elongation and tear strength.

According to an aspect of the present invention, the biodegradable composite material may have a moisture content of 1 to 1,000 ppm, preferably 1 to 500 ppm, but is not limited thereto. When the moisture content is as described above, excellent mechanical properties can be achieved while realizing a high molecular weight.

Another aspect of the present invention is polybutylene terephthalate; aliphatic dicarboxylic acids; aliphatic diols; It is a biodegradable composite material derived by polymerizing a dispersion comprising; and a natural polymer nanofiber at least one selected from nanochitin fibers and nanocellulose fibers.

The biodegradable composite material according to the present invention is manufactured by the above-described manufacturing method, thereby remarkably improving the tensile strength, tensile elongation and tear strength while implementing excellent dispersibility and miscibility of natural polymer nanofibers compared to existing biodegradable materials. can do it

The natural polymer nanofiber according to an aspect of the present invention may be formed of a crosslinker of a polymer derived from polybutylene terephthalate, aliphatic dicarboxylic acid and aliphatic diol. As described above, the natural polymer nanofibers are dispersed in the polymer and physically bonded to exist in a dispersed phase, as well as inducing a reaction with the residual polymer of the polymer to form a cross-linked structure of various shapes. It may be formed as a crosslinking linker to form a crosslinked structure.

According to an aspect of the present invention, the polybutylene terephthalate may have a weight average molecular weight of 10,000 to 100,000 g/mol. Preferably, it may be 10,000 to 80,000 g/mol, more preferably 10,000 to 60,000 g/mol, but is not limited thereto.

According to an aspect of the present invention, the polybutylene terephthalate has a melt flow index of 10 to 50 g/10 min, more preferably 20 to 50 g/10 min, measured at 250° C. and 2.16 kg according to ASTM D 1238. may be, but is not limited thereto.

According to an aspect of the present invention, the biodegradable composite material may have a weight average molecular weight of 10,000 to 100,000 g/mol. Preferably, it may be 20,000 to 100,000 g/mol, more preferably 40,000 to 100,000 g/mol. By being prepared by the manufacturing method according to the present invention, it is excellent in providing a high molecular weight because it is easy to improve the molecular weight.

According to an aspect of the present invention, the biodegradable composite material may have a tensile strength satisfying Equation 1 below.

[Equation 1]

In the above formula 1,

TS ₀ is the tensile strength (MPa) of the biodegradable material that does not contain natural polymer nanofibers, and TS ₁ is the tensile strength (MPa) of the biodegradable composite material.

Specifically, Formula 1 may be 110 to 300%, preferably 120 to 300%, more preferably 125 to 300%, and most preferably 130 to 300%. Even without an excessive amount of reinforcing material, the biodegradable composite material according to the present invention can secure the excellent tensile strength increase rate as described above at the same time as biodegradability, thereby preventing deformation and damage due to external impact as well as having long-term durability. .

According to one aspect of the present invention, the biodegradable composite material may have a tear strength satisfying the following formula (2).

[Equation 2]

In Equation 2,

The TR ₀ is the tearing strength (kgf/cm) of the biodegradable material that does not contain natural polymer nanofibers, and the TR ₁ is the tearing strength (kgf/cm) of the biodegradable composite material.

Specifically, the formula may be 110 to 300%, preferably 115 to 300%, more preferably 120 to 300%. By implementing the excellent tear strength as described above, it is possible to solve the difficulties of practical use of bags and shopping bags, and it is possible to expand to various fields requiring tear strength and biodegradability at the same time.

According to an aspect of the present invention, the biodegradable composite material may have a tensile elongation that satisfies Equation 3 below.

[Equation 3]

In Equation 3,

The TE ₀ is the tensile elongation (%) of the elastomer not containing the nanocellulose, and TE ₁ is the tensile elongation (%) of the thermoplastic elastomer-nanocellulose composite material.

Specifically, Equation 3 may be 110 to 200%. Preferably, it may be 115 to 200%, more preferably 130 to 200%. Even without an excessive amount of reinforcing material, the biodegradable composite material according to the present invention can secure the excellent tensile elongation increase rate as described above, thereby increasing the flexural energy, thereby increasing the practical impact strength of the molded article, injection releasability and continuous workability. This is very excellent.

The biodegradable composite material according to the present invention not only has excellent tensile strength, but also significantly increases tensile strength, tensile toughness and tensile elongation compared to a basic biodegradable material that does not contain natural polymer nanofibers, thereby implementing excellent mechanical properties. Accordingly, it is applicable to various application fields requiring excellent mechanical properties at the same time as biodegradability, such as automobiles, electronics, biomedicine, household goods and other fields.

Hereinafter, the present invention will be described in detail with reference to Examples. However, these are for describing the present invention in more detail, and the scope of the present invention is not limited by the following examples.

In addition, the unit of additives not specifically described in the specification may be weight %.

[Method of measuring physical properties]

(1) Tensile strength and tensile elongation

Examples and comparative examples were placed in the cylinder of the Haake™ Minijet (Thermo Scientific) injection machine, and the cylinder temperature was 200°C, the exposure time was 5 minutes, the injection pressure was 500 bar, and the mold temperature was 150°C, and the dog-bone-shaped specimen (length: 25.5 mm, width: 3.11 mm, thickness: 3.1 mm) was manufactured, and a tensile test was performed in accordance with ASTM D 638 using a universal testing machine (UTM 5982, INSTRON).

Tensile strength change rate (%) was calculated by calculating the change rate compared to the tensile strength of the biodegradable material corresponding to the comparative example through Equation 1 below.

[Formula 1]

Tensile strength change rate = (tensile strength of Example / tensile strength of comparative example) × 100

The change in tensile elongation (%) was calculated using Equation 2 below compared to the tensile elongation of the biodegradable material corresponding to the comparative example.

[Formula 2]

Tensile elongation change rate = (Tensile elongation of Example / Tensile elongation of Comparative Example) × 100

(2) tear strength

Tear strength was measured according to KS M ISO 34-1:2009 test method.

The rate of change in tear strength (%) was calculated by using Equation 3 below to calculate the rate of change compared to the tear strength of the biodegradable material corresponding to the comparative example.

[Formula 3]

Tear strength change rate = (Tear strength of Example / Tear strength of Comparative Example) × 100

(3) weight average molecular weight

The weight average molecular weight is a weight average molecular weight value in terms of standard polystyrene measured by gel permeation chromatography (GPC) using chloroform as a solvent.

GPC equipment: Waters' ACQUITY APC,

Column: ACQUITY APC XT from Waters

Column temperature: 40 °C

Flow rate: 0.6 ml/min

(4) Moisture content measurement

Analysis was performed using a Karl-Fischer titrator from Metrohm.

(5) Measurement of total volatile organic compounds (tVOC)

A heat deposition type gas chromatography mass spectrometer was used, and VOCs were desorbed from the adsorbent by heating the collection tube while venting the inert gas, and analyzed by GC/Mass.

[Example 1]

A mixture was prepared by mixing adipic acid and 1,4-butanediol in a molar ratio of 1:1.6. When the polymer weight with respect to 100% of yield is 100% by weight of nanocellulose fibers (average diameter of 20 nm, average length of 300 nm) in the mixture, it is mixed so as to be 0.04% by weight, and then mixed at 500 W and 20 kHz for 5 minutes. A dispersion was prepared by uniformly dispersing by ultrasonic treatment (VCX500, Sonics & Materials, USA).

Polybutylene terephthalate (LG Chem, LUPOX GP1000S) was dried in a freeze dryer for 24 hours to maintain a moisture content of 500 ppm or less without contact with external atmosphere, and the dispersion was added to polybutylene terephthalate with twin screws. A kneader reactor (Siwis LIST) was put into use. At this time, it was added so that the molar ratio of terephthalic acid and adipic acid in the polybutylene terephthalate was 50:50.

At this time, the polymerization reactor was reacted for 2 hours while removing by-products under a nitrogen atmosphere at a temperature of 240° C. and a reduced pressure of 500 mTorr to obtain a polymer.

The final biodegradable composite material had a weight average molecular weight of 91,300 g/mol, a polydispersity index of 2.06, a color difference index of b*=5.2, a total amount of volatile organic compounds of 28ppm, and a moisture content of less than 1000ppm.

[Example 2]

When the nanocellulose fiber content in Example 1 was 100% by weight of the polymer with respect to the yield of 100%, it was carried out in the same manner except that it was mixed so as to be 0.005% by weight.

[Example 3]

When the nanocellulose fiber content in Example 1 was 100% by weight of the polymer with respect to the yield of 100%, it was carried out in the same manner except that it was mixed so as to be 0.05% by weight.

[Example 4]

When the nanocellulose fiber content in Example 1 was 100% by weight of the polymer with respect to the yield of 100%, it was carried out in the same manner except for mixing so as to be 0.10% by weight.

[Example 5]

When the nanocellulose fiber content in Example 1 was 100% by weight of the polymer with respect to the yield of 100%, it was carried out in the same manner except that it was mixed so as to be 0.20% by weight.

[Example 6]

When the nanocellulose fiber content in Example 1 was 100% by weight of the polymer with respect to the yield of 100%, it was carried out in the same manner except for mixing so as to be 0.50% by weight.

[Example 7]

When the nanocellulose fiber content in Example 1 was 100% by weight of the polymer with respect to the yield of 100%, it was carried out in the same manner except that it was mixed so as to be 2.0% by weight.

[Example 8]

In Example 2, in place of the nanocellulose fibers, the same procedure was performed except for the nanochitin fibers (average diameter of 20 nm, average length of 300 nm). At this time, nanochitin fibers were synthesized by reacting chitin with 1M aqueous hydrochloric acid solution at 100° C. for about 5 hours.

[Example 9]

When the nanochitin fiber content in Example 8 was 100% by weight of the polymer with respect to the yield of 100%, it was carried out in the same manner except that it was mixed so as to be 0.10% by weight.

[Example 10]

When the nanochitin fiber content in Example 8 was 100% by weight of the polymer with respect to the yield of 100%, it was carried out in the same manner except that it was mixed so as to be 0.50% by weight.

[Example 11]

In Example 8, when the polymer weight with respect to the yield of 100% for the nanochitin fiber content was 100% by weight, the same procedure was performed except for mixing so as to be 2.0% by weight.

[Example 12]

The same procedure was carried out in Example 1, except that the molar ratio of terephthalate and adipic acid in polybutylene terephthalate was added to be 30:70.

[Example 13]

The same procedure was carried out in Example 1, except that the molar ratio of terephthalate and adipic acid in polybutylene terephthalate was added to be 70:30.

[Comparative Example 1]

It was carried out in the same manner as in Example 1, except that the nanocellulose fibers were not included.

[Comparative Example 2]

It was carried out in the same manner as in Example 12, except that the nanocellulose fibers were not included.

[Comparative Example 3]

The same procedure was performed except that in Example 13, nanocellulose fibers were not included.

[Comparative Example 4]

Adipic acid, 1,4-butanediol and dimethyl terephthalate were mixed in a molar ratio of 1:1.6:1 to prepare a mixed solution. When the polymer weight with respect to 100% of yield is 100% by weight of nanocellulose fibers (average diameter of 20 nm, average length of 300 nm) in the mixture, it is mixed so as to be 0.04% by weight, and then mixed at 500 W and 20 kHz for 5 minutes. A dispersion was prepared by uniformly dispersing by ultrasonic treatment (VCX500, Sonics & Materials, USA). This was stirred (10 rpm) for 1 hour in a nitrogen atmosphere.

After the dispersion was heated to 140° C. and completely melted, 500 ppm _{of Ti(OBu) 4 was added as a catalyst.} This was stirred at 150 rpm and heated to 180° C. at 10° C./min, and maintained for 2 hours. After that, the temperature was raised to 210 °C, and the by-products were removed while maintaining for 2 hours more. Thereafter, the product was transferred to a reactor equipped with a vacuum outlet and an overhead stirrer, and the temperature was raised to 170° C. in a nitrogen atmosphere. After the product was completely melted, the temperature was raised to 240° C. at 10° C./min while stirring at 50 rpm, and adjusted to 100 mTorr through gradual decompression. When the viscosity of the internal reactant increased by torque measurement through an overhead stirrer, the stirring speed was reduced to 30 rpm and maintained for 60 minutes. The final product was removed from the reactor, quenched with water, and dried in a vacuum oven at room temperature for 48 hours.

The final biodegradable polymer had a recovery amount (97 g, 97%), a weight average molecular weight of 75,000 g/mol, a molecular weight distribution (PDI) of 2.01, and a water content of 1000 ppm or more.

[Comparative Example 5]

In Comparative Example 4, the same procedure was followed except that nanochitin fibers (average diameter 20 nm, average length 300 nm) were used instead of the nanocellulose fibers.

[Experimental Example 1] Confirmation of dispersibility.

As shown in FIG. 1 , the nanocellulose fibers (left) and nanochitin fibers (right) were dispersed in a 1,4-butanediol and adipic acid (1:1.6 molar ratio) solution to 0.1% by weight and then left for a week. After that, it was confirmed whether the nanocellulose fibers and nanochitin fibers were precipitated. Even after a week, it was confirmed that the mixed solution in which the nanocellulose fibers and nanochitin fibers were dispersed was dispersed without being transparently precipitated.

In contrast, as shown in FIG. 2, nanocellulose fibers (left) and nanochitin fibers (right) were mixed with 1,4-butanediol, adipic acid and dimethyl terephthalate (1:1.6:1 molar ratio) in a solution of 0.1 weight. %, and then left for a week, it was confirmed whether the two nanocellulose nanocellulose fibers and nanochitin fibers were precipitated. After one week, precipitation was observed for both nanocellulose fibers and nanochitin fibers.

Through this, it was confirmed that the solution containing dimethyl terephthalate caused the precipitation of the nanocellulose fibers and the nanochitin fibers, so that uniform dispersibility could not be realized.

[Experimental Example 2] Hydrolysis acceleration experiment.

The biodegradable composite materials prepared in Examples 1 to 11 according to the present invention were immersed in 1 M aqueous sodium hydroxide solution. All of them were observed to decompose within 6 months. Through this, it can be confirmed that the biodegradable composite material according to the present invention has biodegradability, and it can be confirmed that it is applicable to various fields requiring such properties.

The tensile strength, tensile elongation and tearing strength of the biodegradable composite material prepared in Examples 1 to 13 and the biodegradable material prepared in Comparative Examples 1 to 5 according to the present invention were measured, and the change rates thereof were calculated to the following table 1 is shown.

Seal
burglar
(MPa) Tensile Elongation Rate of Change
(%) Seal
elongation
(%) Tensile Elongation Rate of Change
(%) tear
burglar
(kgf/cm) Tear strength change rate
(%) weight average molecular weight
(g/mol) Example 1 48 117.1 500 113.6 182 119.0 90k Example 2 41 100.0 445 101.1 152 99.3 87k Example 3 63 151.2 540 122.7 225 147.1 93k Example 4 69 168.3 570 129.5 235 153.6 91k Example 5 65 158.5 533 121.1 218 142.5 97k Example 6 68 165.9 518 117.7 202 132.0 89k Example 7 38 92.7 346 78.6 177 115.7 94k Example 8 41 100.0 434 98.6 154 100.7 91k Example 9 52 126.8 515 117.0 183 119.6 88k Example 10 69 168.3 522 118.6 205 134.0 87k Example 11 38 92.7 380 86.4 145 94.8 90k Example 12 69 168.3 540 122.7 162 105.9 89k Example 13 48 117.1 500 113.6 155 101.3 92k Comparative Example 1 41 - 440 - 153 - 91k Comparative Example 2 52 - 490 - 132 - 88k Comparative Example 3 28 - 345 - 119 - 90k Comparative Example 4 57 - 475 - 166 - 75k Comparative Example 5 55 - 494 - 150 - 71k

As shown in Table 1, in the biodegradable composite material prepared by the manufacturing method according to the present invention, compared to Comparative Examples 1 to 3 made of only biodegradable polymer, nanocellulose fibers and nanochitin fibers do not precipitate and uniform blend It was possible to realize chemical conversion, and it was confirmed that amazing levels of tensile strength, tensile elongation and tear strength were increased.

Moreover, with respect to the total weight of the biodegradable composite material, when the nanocellulose fibers and nanochitin fibers contain 0.01 to 2% by weight, more preferably 0.01 to 1% by weight, tensile strength, tensile elongation and tearing steel It was confirmed that a significant improvement in the figure could be realized at the same time.

Although this is not certain, by linearly dispersing natural polymer nanofibers including aliphatic dicarboxylic acid and aliphatic diol, polybutylene terephthalate is further dispersed, and thus natural polymer nanofibers are more uniformly distributed in the biodegradable polymer. was expected to form.

As in Comparative Examples 4 and 5, when aliphatic dicarboxylic acid, aliphatic diol, and aromatic dicarboxylic acid are all dispersed with nanocellulose fibers and nanochitin fibers and then polymerized, aromatic dicarboxylic acids are side-reacted in the dispersion. It can be confirmed that the precipitation of nanocellulose fibers and nanochitin fibers occurs to induce low dispersibility, and the improvement of mechanical properties is insignificant.

Therefore, it was confirmed that the biodegradable composite material according to the present invention implements excellent complexation of natural polymer nanofibers in the biodegradable polymer without a pretreatment process that causes an increase in cost, and has a synergistic effect on excellent mechanical properties. In addition, it can be applied to various applications requiring them at the same time by securing both excellent mechanical properties and biodegradability.

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 equivalent other embodiments are possible therefrom. Therefore, it will be well understood that the present invention is not limited to the forms recited in the above detailed description. 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 should not be limited to the described embodiments, and not only the claims to be described later, but also all those with equivalent or equivalent modifications to the claims will be said to belong to the scope of the spirit of the present invention. .

Claims (10)

a) aliphatic dicarboxylic acids; aliphatic diols; and a natural polymer nanofiber at least one selected from nanochitin fibers and nanocellulose fibers; mixing and dispersing to prepare a dispersion; and
b) adding polybutylene terephthalate to the dispersion, mixing and dispersing to polymerize
A biodegradable composite material comprising a, wherein the natural polymer nanofiber is formed of a crosslinker of a polymer derived from an aliphatic dicarboxylic acid and an aliphatic diol and the polybutylene terephthalate to form a crosslinked structure manufacturing method. delete The method of claim 1,
A method for producing a biodegradable composite material wherein the molar ratio of terephthalate in the aliphatic dicarboxylic acid and polybutylene terephthalate is 10:90 to 90:10. The method of claim 1,
The natural polymer nanofiber is based on the total weight of the biodegradable composite material, the method for producing a biodegradable composite material comprising 0.001 to 3% by weight. The method of claim 1,
The natural polymer nanofibers have an average diameter of 2 to 200 nm, and a longest length of 100 nm to 10 μm, a method of manufacturing a biodegradable composite material. polybutylene terephthalate; aliphatic dicarboxylic acids; aliphatic diols; And as a biodegradable composite material induced by polymerizing a dispersion comprising; and at least one natural polymer nanofiber selected from nanochitin fibers and nanocellulose fibers,
The biodegradable composite material in which the natural polymer nanofiber is formed of a crosslinker of a polymer derived from an aliphatic dicarboxylic acid and an aliphatic diol and the polybutylene terephthalate to form a crosslinked structure 7. The method of claim 6,
The polybutylene terephthalate is a biodegradable composite material having a weight average molecular weight of 10,000 to 100,000 g/mol. delete 7. The method of claim 6,
The biodegradable composite material is a biodegradable composite material having a tensile strength satisfying Equation 1 below.
[Equation 1]

In the above formula 1,
TS ₀ is the tensile strength (MPa) of the biodegradable material that does not contain natural polymer nanofibers, and TS ₁ is the tensile strength (MPa) of the biodegradable composite material. 7. The method of claim 6,
The biodegradable composite material is a biodegradable composite material having a tear strength that satisfies Equation 2 below.
[Equation 2]

In Equation 2,
The TR ₀ is the tearing strength (kgf/cm) of the biodegradable material that does not contain natural polymer nanofibers, and the TR ₁ is the tearing strength (kgf/cm) of the biodegradable composite material.

Images