KR100824719B1 - Bio-degradable food-packing materials consisting of starch-contained nonwoven-nanofabrics and preparation methods therefor - Google Patents

Abstract

The present invention relates to nanofiber nonwovens having biocompatibility and biodegradation characteristics and methods for their preparation.

The nanofiber nonwoven fabric of the present invention is prepared by dissolving starch and polyvinyl alcohol in pure water and spinning to less than 1 μm in diameter. Degradation rate and strength, the diameter of the fiber can be adjusted, and because it has nano-porosity, it has a characteristic of blocking external pollutants while having human breathability, it can be applied to various fields such as food packaging materials, sanitary materials.

Electrospinning, biocompatible nanofibers, biodegradable nanofibers

Description

Bio-degradable food-packing materials consisting of starch-contained nonwoven-nanofabrics and preparation methods therefor}

1 is a scanning electron micrograph of soluble starch / PVA-containing nanofibers prepared according to an embodiment of the present invention,

(a) is a photograph of starch / PVA = 70/30 wt.%,

(b) is a starch / PVA = 50/50 wt.% photo,

(c) is photograph of starch / PVA = 30/70 wt.%.

Figure 2 is a graph showing the fiber diameter distribution of soluble starch / PVA biodegradable nanofiber nonwoven fabric prepared according to an embodiment of the present invention.

Figure 3 is a graph showing the thermogravimetric (TGA) change of soluble starch / PVA biodegradable nanofiber nonwoven fabric prepared according to an embodiment of the present invention.

delete

delete

delete

delete

delete

delete

delete

delete

delete

4 is a scanning electron micrograph of biodegradable nanofibers of starch / PVA crosslinked by boron according to an embodiment of the present invention,

(a) 5% boronic acid (H ₃ BO ₃ ) added

(b) crosslinked by addition of 7% boronic acid.

5 is a graph showing the thermogravimetric change of biodegradable nanofibers of starch / PVA crosslinked by boron according to an embodiment of the present invention.

The present invention relates to a biodegradable and biocompatible nonwoven fabric composed of ultra-fine nanofibers of less than 1 μm in diameter prepared by electrospinning a drug with starch and polyvinyl alcohol, and a composition thereof.

[Biodegradable Polymer]

In general, a biodegradable polymer refers to a polymer in which the chain introduced into the polymer by the microorganism is cut and inorganicized, and factors such as environment, oxygen, temperature, humidity, pH, salt, nutrients, and properties of the polymer itself during the biodegradation process. The rate of decomposition or form of decomposition will vary. Subdividing biodegradable polymers can be broadly classified into biodegradability decomposed by water and microorganisms and photodegradability decomposed by light. In addition, starch decomposes and decomposes substrates in which the polymer matrix itself is decomposed. It can be classified into the addition type that is decomposed by additives such as metal compounds. In the case of the additive type, the price is relatively inexpensive and there is an advantage in that it can be directly applied, but it has a disadvantage of slow decomposition rate. In addition, the biodegradable polymer may be classified into a natural polymer and a synthetic polymer according to the raw material. Among the materials practically used as a biodegradable synthetic polymer raw material, polyhydroxyalkanoate (PHA) containing α-hydroxy acid as a structural unit is best known, and starch, chitosan, etc. are well known as biodegradable natural polymer raw materials. Known.

Typical fields of use of biodegradable polymers are environmental products, and packaging materials using various biodegradable polymers are widely used in terms of preventing environmental pollution. Biodegradable or biocompatible polymers that decompose in the tissues of the human body are attracting attention because they can be used as high value-added materials such as food, pharmaceutical special packaging materials, surgical sutures, drug delivery materials and pharmaceuticals. However, polymers for use in such articles have specific properties in comparison with general environmental products in that they are required to be decomposed and absorbed without any detoxification in the body and not to be accumulated in the body.

Specific technical trends for biodegradable polymers, in particular biodegradable fibers, are well known polylactic acid (PLA) obtained from corn and potatoes, tencels (Tencel), regenerated cellulose, milk-incorporated rayon, and fibers incorporating chitosan. Among them, Lakron of Kanebo, Japan, is a polylactic acid fiber manufactured by melt spinning method using corn as a main raw material, and is known to have excellent melting point and Young's modulus and color fastness to about 4 grades. .

On the other hand, starch is the raw material most attention as a biodegradable natural polymer. Starch, a storage material of nutrients in plants, is a polysaccharide formed by condensation of α-D-glucose, which is a branch-free chain through the combination of α-1,4 glicoside without the branching of D-glucose. Amylopectin, a starch in the form of polymerized helical amylose and a branched form consisting of more than 1000 glucose in the molecule.

Starch is different in shape and size depending on the type of plant, but all are macromolecules, and are mainly produced from corn, sweet potato, potato, wheat, and flesh, and are widely used in processed foods, textiles, paper industry, pharmaceutical industry, etc. Is being used. More than half of the carbohydrates ingested by humans are known as starches, and they are rapidly hydrolyzed by α-amylase, which is mainly secreted by the pancreas or salivary glands.

Starch is emerging as a biodegradable polymer raw material because of its excellent biodegradability, cheaper price than other raw materials, abundant resources and easy supply. Starch has a big advantage in that it is a non-toxic natural raw material that can be supplied indefinitely as long as there is a green plant on the earth, compared to petroleum resources which are in danger of being depleted. Starch is insoluble in water and has a property of precipitation, but soluble starch is produced and sold by steaming at high pressure or treating with dilute acid to cause some hydrolysis.

The development of biodegradable materials using starch is especially the most practical use of biodegradable plastics based on starch as a packaging paper.In order to control the hydrolysis rate of starch, starch itself is esterified, oxidized, etherified, Researches are being actively carried out through crosslinking and the like, and in particular, researches on blending starch and various biodegradable polymers to form a film and characterizing them have been conducted.

Meanwhile, conventional biodegradable fiberization methods using fibrous forming natural polymers and synthetic polymers typically include melt spinning and solution spinning, and these methods extrude, stretch, and finely polymerize a melt through a spinneret nozzle. It is a way to wind up. However, this method has a limitation in reducing the fiber diameter to less than 10 μm because the fiber is manufactured by mechanical force, and additional processes such as needle punching or spunlace are required to make it into a nonwoven fabric or felt. In addition, processes such as weaving and weaving are essential. In addition, since the fiber diameter is about 100-1000 times thicker than the fiber produced by electrospinning at about 10 μm to 20 μm, there is a fear of secondary infection due to penetration of viruses or other contaminants when using the human body.

In contrast, an electrospinning method is known as a breakthrough method in which nanofibers having a fiber diameter of less than 1 μm can be obtained by applying an electrostatic attraction to the polymer melt. Electrospinning method is a method that can produce nanofibers by controlling the diameter of fiber by various variables such as spinning environment, applied voltage, viscosity of polymer melt, electric conductivity, surface tension, and so on. Since nanofibers can be prepared by complexing, dispersing, and functionalizing, research is being actively conducted in various industrial fields. However, in the case of nanofibers produced by electrospinning, most of them are prepared by dissolving a polymer using an organic solvent, and thus an organic solvent remains on the inside and inside of the nanofiber, which is a significant problem in using it as a biocompatible nanofiber nonwoven fabric. There is this.

Looking at the development example of the fiber using a natural raw material, for example, the Republic of Korea Patent No. 10-0107854, describes a biodegradable fiber and a method for producing the same using a natural polyester polypyroxy butyl acid (PHB) However, in this method, the diameter of the fiber produced using the melt spinning and cold stretching method has a thickness of several denier to hundreds of denier (several micrometers to several tens of micrometers), and when non-woven fabrics, an additional process such as secondary processing is required. If necessary, the decomposition rate is slow, and the overall manufacturing process is complicated.

In addition, the Republic of Korea Patent Publication, 1992-0020742 is also produced starch fiber through the melt spinning method, the diameter of the fiber is large, the disadvantage of the use of secondary mixtures such as disintegrators, additives for melt spinning, and the resulting biological There may be a problem in suitability, there is a disadvantage that expensive equipment such as a twin extruder (twin extruder) is required.

Accordingly, the present invention, the diameter of the biodegradable polymer fibers, which are conventionally produced by the melt spinning method as described above to the nanometer level, in particular using a low-cost and biodegradable or biocompatible properties such as starch It is an object to provide a nanofiber nonwoven fabric.

The present invention also aims to provide biocompatible, biodegradable nanofiber nonwoven fabrics by using only pure water as a solvent to enhance biocompatibility, to control strength and fiber diameter, and to provide biocompatibility and biodegradable nonwoven fabrics.

The present invention also modifies the starch, or adjusts the content of starch and polyvinyl alcohol to control the biodegradation rate and strength of the nanofiber nonwoven fabric, while having a good mechanical strength and flexibility by a method such as water repellent treatment and heat bonding An object of the present invention is to provide various biodegradable nonwoven fabrics such as hygienic materials and food packaging materials having excellent water resistance.

In order to achieve the above object, the present invention provides a method for producing a starch-containing biodegradable nanofiber nonwoven fabric, characterized in that the electrospinning the spinning solution dissolved starch and polymer in water.

In the production method of the present invention, the polymer may be polyvinyl alcohol, but is not limited thereto.

As the starch raw material of the present invention, any one produced from potato, corn, sweet potato, wheat, rice and other plants can be used, and it is preferable to use soluble starch through pretreatment.

In the present invention, the spinning method is suitable for producing nano-sized fibers by electrospinning. The starch and the polymer are dissolved in water to prepare a spinning solution, and then a high voltage (for example, -60 kV) is applied thereto to obtain a nonwoven fabric. The electrospinning method is not particularly limited, and an appropriate apparatus or radiation environment can be selected according to the use of the final product.

The present invention also provides a method for producing a biodegradable nanofiber nonwoven fabric further comprising the step of modifying the starch by adding a modifier to the spinning solution.

The modification of starch can be performed by the method of macromolecules etc., for example, by using boronic acid as a modifier and forming bridge | crosslinking between a polymer and a soluble starch. However, the modification is not particularly limited thereto, and various modification additives may be used as appropriate depending on the purpose of the final product.

delete

delete

delete

The present invention further provides a starch-containing biodegradable nanofiber nonwoven fabric prepared by the above method.

The present invention further provides a starch-containing biodegradable nanofiber nonwoven fabric prepared by the above manufacturing method and used as a hygiene material or a food packaging material.

Hereinafter, embodiments of the starch-containing biodegradable nanofiber nonwoven fabric according to the present invention will be described in detail with reference to the accompanying drawings.

delete

delete

This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

EXAMPLE

Example  1 starch / PVA  Preparation of Nanofiber Nonwovens

Soluble starch and polyvinyl alcohol (PVA, Mw = 1500) were respectively 10/90, 20/80, 30/70, 50/50. Mix at a weight ratio of 70/30, 80/20, 90/10, and make the concentration of starch 20% by weight and 10% by weight of PVA with respect to water, so that the concentration of the total spinning solution is 20% by weight. To adjust.

The spinning solution prepared in this way was connected to the spinneret, a voltage of 50 kV was applied to the spinneret, and discharged at 0.5 cc / g per hole while maintaining the distance between the spinneret and the current collector at 20 cm. Carried out.

The electron micrograph of the fiber obtained at this time, and the diameter of a fiber are shown in FIGS.

In the case of FIG. 1 (a) where the starch / PVA content is 70/30 weight ratio as shown in the photograph of FIG. 1, it was observed that the bead phase and the fiber diameter were nonuniform in the prepared starch / PVA nanofibers. As it increased to 50 and 70% by weight, no bead phase was observed, and uniform fibers were obtained. As shown in FIG. 2, when the PVA / starch content was 30/70 according to the content of PVA and starch, the average fiber diameter was When the PVA / starch content is about 50/50 at about 300 nm, the average fiber diameter is about 250 nm, and when the PVA and starch content is about 70/30, the average fiber diameter is about 200 nm. It was found to decrease gradually. That is, as the content of PVA with excellent radioactivity increases, the decrease in defects and the fiber diameter decrease in the manufactured nanofibers.

3 shows a thermogravimetric (TGA) graph of a starch / PVA nanofiber nonwoven fabric under a nitrogen gas atmosphere. As shown in the figure, the change in weight was small as the PVA content was increased in the temperature range below 400 ℃, and in the temperature range above 400 ℃, the weight loss was relatively decreased due to the carbon atoms contained in the starch, which is a macromolecule. It can be seen that it appears low. That is, in the temperature range of less than 400 ℃ as the starch content increases due to the evaporation of the moisture contained in the starch, the weight decreases significantly, which means that the decomposition rate can be controlled by blending the PVA and starch.

Example 2 Improvement of Nanofiber Nonwoven Fabrics According to the Present Invention

delete

delete

delete

delete

delete

delete

Soluble starch and PVA were mixed at 50/50 wt%, respectively, and 5% and 7% of boronic acid (H ₃ BO ₃ ) compared to soluble starch / PVA, respectively, dissolved in water, stirred for 24 hours and crosslinked to spin spinning solution. Was prepared. The crosslinked spinning solution was electrospun in the same manner as in Example 1 to obtain boronic acid-containing soluble starch / PVA nanofiber nonwoven fabric. The scanning electron micrograph of the sample obtained at this time is shown in FIG. As shown in FIG. 7, when the content of boronic acid increased from 5% to 7%, the average fiber hardness increased from 350 to 450 nm, and the diameter of the fiber averaged about 100 as compared to FIG. It can be seen that the increase of about nm. This result is considered to be a phenomenon in which the molecules of PVA and boron starch by boronic acid are macromolecules by crosslinking. The thermogravimetric analysis of the nanofiber nonwoven crosslinked by the addition of boronic acid is shown in FIG. 5. As shown in FIG. 5, it can be seen that thermal properties are increased by adding boronic acid as compared to soluble starch / PVA = 50/50 (FIG. 2) in the range below 400 ° C. temperature. This is considered to be the result of forming intermolecular bridge | crosslinking of PVA and soluble starch by boronic acid.

Example 3 Control of Biodegradation Rate of Nanofiber Nonwoven Fabrics According to the Present Invention

The biodegradable or biocompatible nanofibers prepared by the methods of Examples 1 and 2 were calendered and heat-sealed by calendering at room temperature and 60 ° C., and the heat-sealed nanofiber nonwoven fabric again contained an organic solvent. It was treated with 3% by weight compared to nanofibers using an environmentally friendly, water-dispersible fluorine-based water repellent, which was dried for 200 seconds at a temperature of 150 ° C. for water repellent processing. The biodegradable nanofiber nonwoven fabric thus obtained was compared with a film made of 50/50 wt% of PVA / soluble starch, and the flexibility, tensile strength, and water pressure were measured. The results are shown in Table 2. Both the electrospun sample and the thermally fused sample were excellent in flexibility, and in the case of the samples having relatively low tensile strength, the tensile strength was relatively increased by thermal fusion, and the water pressure was increased by the water repellent treatment. These results suggest that the biodegradation rate can be controlled by mixing ratio of raw materials (starch and PVA), water repellent treatment and heat fusion.

division Raw material composition Fiber diameter (nm) flexibility The tensile strength Water pressure (mmaq) Example PVA / Starch (70/30) 200 ○ × 35-50 Example PVA / starch (50/50) 250 ○ × 25-45 Example PVA / Starch (30/70) 300 ○ × 20-40 Example PVA / starch / boronic acid (50/50/5) 350 ○ ○ 45-75 Example PVA / starch / boronic acid (50/50/7) 400 ○ ○ 50-80 Example PVA / starch (50/50) heat fusion / water repellent 250 ○ ○ 65-120 Example PVA / starch / boronic acid (50/50/7) heat fusion / water repellent 400 ○ ○ 70-130 Comparative example PVA / starch (50/50) film Film thickness 90㎛ ○ ○  -

* Flexibility measurement: The measurement was conducted according to JIS L1096-6's 19.1A (45 ° cantilever method). And the average value of the horizontal direction was computed, and the thing of the range of 100-150 mm was made pass (O), and the thing of other than that was rejected (x).

* Tensile strength measurement: According to JIS L1906-4, the sample size was 5 X 30 cm, measured three times under the condition of 10 cm / m of tensile speed, and the winding direction of the fiber was spun in the longitudinal direction of the fiber during spinning with each average value. And it calculated with the strength per 100 g / m <2> by making the direction which rotated 90 degrees transversely, and made the pass (O) and the others (x) the thing of 30 N / 5cm or more in both sides horizontally.

* The water pressure measurement was performed three times with a sample size of 15 X 15 cm in accordance with No. 1 water resistance test A of JIS L109206 to make the water resistance of the nonwoven fabric.

As described above, the nanofiber nonwoven fabric according to the present invention has biocompatibility characteristics, and by controlling the starch and polymer content, biodegradation rate and strength of the nonwoven fabric, fiber diameter, etc. The human body has respiratory properties while blocking external pollutants. In addition, by using only pure water as a solvent, there is an advantage of low manufacturing cost and high biocompatibility.

In addition, by modifying the raw material and heat-sealing / water-repellent treatment using boronic acid, etc., it has a good mechanical strength and flexibility, has excellent water resistance, and spins the biodegradable nanofiber nonwoven fabric suitable for sanitary materials as well as three-dimensional nonwoven fabric. There is an advantage that can be manufactured in a state.

Claims (8)

Soluble starch, biodegradable polymer and crosslinking agent are dissolved in water to make a spinning solution, and the spinning solution is electrospun to make nanofiber, and then heat-sealed to obtain a nanofiber nonwoven fabric, which is then treated with a water-dispersible fluorine-based water repellent A method of producing a biodegradable food packaging material comprising a starch-containing nanofiber nonwoven fabric, which is then subjected to high temperature drying. The method of claim 1, wherein the polymer is polyvinyl alcohol. The method according to claim 1, wherein the crosslinking agent is boronic acid (H ₃ BO ₃ ), characterized in that the manufacturing method of biodegradable food packaging material consisting of starch-containing nanofiber nonwoven fabric. delete delete A biodegradable food packaging material made of starch-containing nanofiber nonwoven fabric prepared by the method according to any one of claims 1 to 3. delete delete

Images