KR102699904B1 - Method for preparing biodegradable plastic from Ulva sp. and biodegradable plastic prepared by the same - Google Patents

Abstract

The present invention provides a method for producing a biodegradable plastic, including a step of extracting cellulose from Ulva sp. seaweed to produce a film. Accordingly, the method for producing a biodegradable plastic of the present invention uses cellulose extracted from Ulva sp. seaweed as a material, thereby naturally controlling the cause of green algae bloom and producing an environmentally friendly plastic product that does not produce hazardous substances when disposed of.

Description

Method for preparing biodegradable plastic from Ulva sp. and biodegradable plastic prepared by the same

The present invention relates to a method for producing a biodegradable plastic and a biodegradable plastic film produced thereby, and more specifically, to a method for producing a biodegradable plastic using cellulose derived from Ulva sp., which causes green algae, and a biodegradable plastic film produced thereby.

Recently, as interest in the marine bio industry has increased, industries such as natural products, biomaterials, and bioenergy using marine useful organisms have grown rapidly. Marine useful organisms refer to marine biological resources that need to be preserved and have high economic value, and a huge amount of information on genetic information, extracts, etc. is being accumulated. In particular, algae including seaweeds are receiving attention in the bioindustry field because they provide diverse and abundant marine biological resources due to their rapid growth and excellent reproductive ability, and also because they provide eco-friendly materials.

On the other hand, some seaweeds react sensitively to changes in the surrounding environment and show rapid increases in biomass, so seaweed blooms are one of the unavoidable natural disasters. A representative seaweed that causes disturbances in the marine ecosystem worldwide is Ulva. The bloom caused by Ulva is called a green tide, and the representative areas of occurrence have been reported in France and China. Among these cases, the green tide occurring along the East China Sea coast is reported to be the largest in the world, and since 2008, the Ulva bloom has been reported to have a maximum distribution area of approximately 60,000 ^km2 and a maximum biomass of over 60 tons/ ^km2 . It has also been reported that it moves along the ocean currents and covers the coast of China or crosses the West Sea, causing damage to Korea.

Since the species causing seaweed blooms have the characteristic of rapid growth when carbon dioxide and inorganic nutrients in the seawater are not limited, it is predicted that the intensity of material inflow into coastal ecosystems will increase compared to the past. Seaweed blooms of this taxonomic group have been frequently reported in Korea as well. Since 2008, it has been reported that Chinese planktonic harmful green algae-causing species have invaded the southwestern coastal waters including Jeju Island, and since the 2000s, the indigenous Korean scutellaria baicalensis has been showing explosive growth and causing great damage. Since 2012, harmful green algae blooms have also been reported around Sihwa Lake. Therefore, the need for management measures for seaweed blooms that disrupt the ecosystem and cause damage to human activities has been continuously raised.

The sclerotial kelp is found in all coastal waters of Korea, but it is sensitive to eutrophication and has the characteristics of opportunistic macroalgae that show explosive growth. Because of this characteristic, it causes massive property damage every year due to blooms of green algae in Jeju waters and some coastal waters of Korea. In particular, the rapid increase in human activities due to population growth and industrialization will increase the intensity of pollutants entering coastal ecosystems, and as a result, it is predicted that the frequency and intensity of blooms of opportunistic macroalgae will increase further.

First, research on the extraction and utilization of useful substances using biomass of harmful algae bloom-causing species has a very high potential for development. There is a lot of international interest in the development of industrialization-related technologies for seaweed biomass, and in the case of bioenergy projects, the need for the development of industrial utilization technologies for byproducts is also emerging. Securing useful substances using seaweed with secured biomass will provide international competitiveness in related industries.

It is also valuable as a potential biomaterial that can be a green light for plastic pollution, which is a problem in the marine environment. Bioplastics are raw materials for eco-friendly plastics that are emerging as a supplement or substitute for plastics produced from existing chemical fuels. They can generally be divided into biodegradable plastics and bio-based plastics, and biodegradable plastics are those that are completely decomposed into water and carbon dioxide through the action of microorganisms such as bacteria or fungi and decomposing enzymes. Therefore, biodegradable plastics can be landfilled without the need for recovery and treatment after use, and are known as eco-friendly materials because they do not emit harmful substances even when burned.

Biodegradable plastics are produced from biomass (natural; PLA, TPS, PHA, AP, CA, etc.) or fossil fuel-based compounds (petroleum; PBS, PES, PVA, PCL, PBAT, etc.). Natural biodegradable plastics have the advantages of excellent biodegradability and carbon reduction, but they are expensive, have poor physical properties, and can decompose during distribution. Environmentally friendly biodegradable polymers include natural biopolymers extracted from plants and animals in the sea or on land, polymers produced by microorganisms, and biodegradable synthetic polymers that can be biodegraded by applying polymer synthesis technology to natural raw materials such as amino acids, sugars, and polyesters. Representative biomaterial polymer materials include polysaccharides such as cellulose, starch, chitin, chitosan, pectin, and alginic acid; proteins such as casein, whey, soy protein, corn, and gelatin; and lipids such as wax, oil, and fatty acids. Since most of these ingredients are known to be obtained from grains currently used as food resources, it is predicted that ethical conflicts will arise in the near future. In particular, the bioenergy industry using grains and wood has failed to solve ethical problems of food resources and environmental destruction, and similarly, a solution was found in microalgae, and the possibility of exploring materials for biodegradable plastics in marine plants has also increased.

We attempted to develop a biodegradable film based on biopolymers using the pathogenic species, and to develop food packaging materials with secured properties. Biopolymer materials that can be obtained from marine organisms are polysaccharides such as cellulose, alginic acid, chitosan, and pectin, and green algae, the pathogenic species, contain the most cellulose among polysaccharides. Research on manufacturing biodegradable packaging materials using renewable resources and natural materials is attracting increasing attention. In recent years, interest in polymers from natural resources has increased due to their potential applications in various fields including the food industry.

Cellulose is the most abundant polymer material obtained from nature and has many advantages such as excellent mechanical strength and biodegradability. The polymer composite application of cellulose can be widely used in food and pharmaceutical packaging materials due to its low air permeability, excellent mechanical properties, and transparent optical properties. Cellulose is the most important substrate resource that can be obtained through various routes ranging from wood, plant fiber, marine animals, algae, fungi, vertebrates, and bacteria. Meanwhile, cellulose is used as a resource in packaging and other applications due to its unique properties such as biodegradability, excellent mechanical properties, and sustainability. In addition, cellulose can minimize the accumulation of biomass and reduce the accumulation caused by the use of non-biodegradable synthetic materials. Among various biomass, agricultural and marine residues have the advantages of low cost, abundant resources, and easy utilization, so that biomass waste can be naturally controlled and utilized.

Ulva ohnoi, known as the main species causing green algae blooms, is a seaweed that is causing green algae blooms along the Jeju coast. The green algae that occurs along the Jeju coast averages over 18,000 tons per year. The amount of laver collected along the Jeju coast is increasing every year. The inflow of high-concentration groundwater from the seabed along the Jeju coast is promoting the growth of green algae, causing green algae blooms.

Korean Patent No. 1,255,090

The present invention is intended to solve the above problems, and provides a method for manufacturing a biodegradable plastic that can naturally control the cause of green algae blooms by using cellulose extracted from Ulva sp. seaweed as a material and manufacture an environmentally friendly plastic product that does not generate hazardous substances when disposed of, and a biodegradable plastic manufactured thereby.

According to one aspect of the present invention,

A method for producing a biodegradable plastic is provided, comprising the step of producing a film by extracting cellulose from seaweed of the genus Ulva sp .

The method for manufacturing the above biodegradable plastic film is as follows:

(a) a step of producing Ulva powder by crushing Ulva sp. seaweed;

(b) a step of dewaxing the above-mentioned powder;

(c) a step of removing ulvan from the dewaxed safflower powder and washing it;

(d) a step of bleaching the washed seaweed powder;

(e) a step of sequentially performing a base treatment and an acid treatment on the bleached seaweed powder;

(f) a step of preparing a cellulose solution by dissolving the bleached kelp powder in a cellulose solvent; and

(g) a step of immersing the cellulose solution in a coagulating solvent to obtain a cellulose gel and then drying it to produce a cellulose plastic;

The above Ulva sp. seaweed may be any one selected from Ulva ohnoi , Ulva lactuca , Ulva pertusa , Ulva fasciata , Ulva rigida , and Ulva linza .

In step (b), the dewaxing can be performed using any one mixed solvent selected from a mixed solvent of toluene and ethanol, a mixed solvent of acetone and ethanol, and a mixed solvent of hexane and methanol.

Step (c) can remove ulvan by mixing with any one chelator selected from ammonium oxalate, oxalate, oxalic acid, acetic acid, malic acid, maleic acid, EDTA (Ethylenediamine tetraacetic acid), DPTA (Diethylenetriamine pentaacetic acid), NTA (Nitrilotriacetic acid), DTPA (Diethylenetriamine pentaacetic acid), HEDTA (N-hydroxyethyl ethylenediamine tetraacetic acid), and IDA (Iminodiacetic acid).

In step (d), the bleaching can be performed using a mixed solution of a chlorine-based oxidizing bleach and an acid.

The above chlorine-based oxidizing bleach may be any one selected from sodium chlorite, sodium hypochlorite, and sodium chlorite.

The above acid may be any one selected from acetic acid, formic acid, succinic acid, citric acid, malic acid, maleic acid and oxalic acid.

In step (e), the base treatment and acid treatment can be performed using a strong base and a strong acid.

In step (f), the cellulose solvent may be any one selected from DMAc (N,N-dimethylacetamide)/LiCl, NMMO (N-methylmorpholine-N-oxide)/H ₂ O, Ca(SCN) ₂ (calcium thiocyanate)/H ₂ O, TFA (trifluoroacetic)/chlorinated alkane, and liquid ammonia/ammonium thiocyanate (NH ₄ SCN).

In step (g), the coagulating solvent may be any one selected from water, methanol, ethanol, isopropanol, acetone, DMAc, DMF (Dimethyl formamide), DMSO (dimethyl sulfoxide), and dioxane.

In step (g), the cellulose solution can be spread on a plate and then immersed in a coagulating solvent to produce a film-shaped biodegradable plastic.

According to another aspect of the present invention,

A biodegradable plastic manufactured according to the above method for manufacturing a biodegradable plastic is provided.

The above biodegradable plastic may be in the form of a film.

The method for manufacturing a biodegradable plastic of the present invention uses cellulose extracted from Ulva sp. seaweed as a material, thereby naturally controlling the cause of green algae blooms and manufacturing an environmentally friendly plastic product that does not generate hazardous substances when disposed of.

In addition, the biodegradable plastic manufactured according to the method for manufacturing a biodegradable plastic of the present invention not only naturally decomposes when discarded and does not produce substances harmful to the environment, but also has high transparency and excellent durability when manufactured in a film form.

Figure 1 is a flow chart sequentially showing a method for manufacturing a biodegradable plastic of the present invention.
Figure 2 is a photograph of the cellulose film of Example 1.
Figure 3 is a photograph of a biodegradable film manufactured according to each of Examples 1 to 3.

Below, various aspects and various implementation examples of the present invention are described in more detail.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention.

However, the following description is not intended to limit the present invention to specific embodiments, and if it is determined that a detailed description of a related known technology may obscure the gist of the present invention when explaining the present invention, the detailed description is omitted.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprises" or "has" and the like are intended to specify the presence of a feature, number, step, operation, component, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, or combinations thereof.

Figure 1 is a flow chart sequentially showing the method for manufacturing a biodegradable plastic of the present invention. Hereinafter, the method for manufacturing a biodegradable plastic of the present invention will be described.

The method for producing a biodegradable plastic of the present invention is characterized by extracting cellulose from seaweed of the genus Ulva sp. to produce a film. Specifically, the method is as follows.

First, in the seaweed ( Ulva sp. ) Grind seaweed to produce seaweed powder (step a).

The Ulva sp. seaweed is preferably any one selected from among Ulva ohnoi, Ulva lactuca , Ulva pertusa , Ulva fasciata , Ulva rigida , and Ulva linza , and more preferably, Ulva ohnoi, which is causing green algae damage along the coast of Jeju Island, Korea. Ulva ohnoi is a recently classified subtropical species that is distributed throughout Jeju Island and has a maximum length of 3 to 4 m, making it the most widely distributed along the coast of Korea. It is characterized by high nutrient absorption rate and high growth rate.

Next, the above-mentioned powder is dewaxed (step b).

The above dewaxing means removing the wax component by adding a solvent to the seaweed.

The solvent used for the above dewaxing may be a mixed solvent of toluene and ethanol, a mixed solvent of acetone and ethanol, or a mixed solvent of hexane and methanol.

Afterwards, ulvan is removed from the dewaxed safflower powder and washed (step c).

The above ulvan is a carbohydrate storage form in seaweeds such as laver, and as an example of removing ulvan, the components removed at this time may include carrageenan, alginic acid, fucoidan, laminaran, etc. in addition to ulvan.

Ulvan contained in the powder of sea squirt can be removed by mixing and reacting with any one chelator selected from ammonium oxalate, oxalate, oxalic acid, acetic acid, malic acid, maleic acid, EDTA (Ethylenediamine tetraacetic acid), DPTA (Diethylenetriamine pentaacetic acid), NTA (Nitrilotriacetic acid), DTPA (Diethylenetriamine pentaacetic acid), HEDTA (N-hydroxyethyl ethylenediamine tetraacetic acid), and IDA (Iminodiacetic acid), and ammonium oxalate is preferably used. At this time, the reaction is preferably performed at 80 to 120°C for 30 to 100 minutes, and more preferably at 90 to 110°C for 50 to 80 minutes. If the reaction is performed for less than 30 minutes at a temperature below 80℃, ulvan removal may be insufficient, and if the reaction is performed for more than 100 minutes at a temperature exceeding 120℃, unnecessary process costs may be incurred or necessary components may be removed due to excessive washing.

Afterwards, the washing process can be completed by repeating the process of mixing water, stirring, and filtering several times.

Next, the washed and ulvan-free kelp powder is bleached (step d).

It is preferable to perform the above bleaching using a mixed solution of a chlorine-based oxidizing bleach and an acid.

As the above chlorine-based oxidizing bleach, it is preferable to use sodium chlorite, sodium hypochlorite, sodium chlorite, etc., and more preferably, sodium chlorite can be used.

It is preferable to use a weak acid such as acetic acid, formic acid, succinic acid, citric acid, malic acid, maleic acid, or oxalic acid as the acid above, and acetic acid can be used more preferably.

Thereafter, the bleached seaweed powder is sequentially subjected to alkali treatment and acid treatment (step e).

The above base treatment is preferably performed with a strong base, and the strong base may be potassium hydroxide, sodium hydroxide, calcium hydroxide, barium hydroxide, etc.

It is preferable to perform the above acid treatment with a strong acid, and the strong acid that can be used is hydrochloric acid, nitric acid, sulfuric acid, etc.

Hemicellulose contained in the seaweed can be removed by the above-mentioned basic treatment and acid treatment.

Thereafter, the bleached kelp powder is dissolved in a cellulose solvent to prepare a cellulose solution (step f).

The above cellulose solvent refers to a solvent that directly dissolves cellulose, and it is preferable to use DMAc(N,N-dimethylacetamide)/LiCl, NMMO(N-methylmorpholine-N-oxide)/H ₂ O, Ca(SCN) ₂ (calcium thiocyanate)/H ₂ O, TFA(trifluoroacetic)/chlorinated alkane, liquid ammonia/ammonium thiocyanate (NH ₄ SCN), etc., and more preferably, DMAc(N,N-dimethylacetamide)/LiCl can be used.

After dissolving cellulose using the above cellulose solvent, it is preferable to additionally perform centrifugation to remove undissolved substances and air bubbles.

Finally, the cellulose solution is immersed in a coagulating solvent to obtain a cellulose gel, which is then dried to produce a cellulose plastic (step g).

The above coagulating solvent may be water, methanol, ethanol, isopropanol, acetone, DMAc, DMF (Dimethyl formamide), DMSO (dimethyl sulfoxide), dioxane, etc., and preferably, ethanol, acetone, and water can be used.

The above cellulose solution can be spread on a plate and then immersed in a coagulating solvent to produce a film-shaped biodegradable plastic.

In addition, the present invention provides a biodegradable plastic manufactured according to the method for manufacturing a biodegradable plastic described above.

It is preferable that the above biodegradable plastic is in the form of a film.

Hereinafter, examples according to the present invention will be described in detail.

[Example]

Example 1

(1) Preparation of large-leaved seaweed ( Ulva ohnoi ) powder

The harvested large hairtail ( Ulva ohnoi ) was washed clean in running water to remove foreign substances, dried in a dryer at 50℃ for 24 hours, and then ground finely in a vacuum mixer to produce large hairtail powder.

(2) Dewaxing

Weigh 18 g of large-leaved laver powder and add it to a solvent mixed with toluene and ethanol (volume ratio = 2:1) and rapidly stir at room temperature for 7 hours to dewax.

(3) Ulvan removal and filtration

The dewaxed sample was mixed with 15 mM ammonium oxalate and stirred at 100°C for 1 hour. After the mixture was sufficiently cooled, the remaining sample was washed with distilled water and filtered. After filtering, 600 ml of distilled water was mixed with the sample, stirred for 15 minutes, and filtered again. The filtration process was repeated several times.

(4) Bleaching

The filtered sample was mixed with sodium chlorite (NaClO ₂ ) (2.5 wt%) and acetic acid (5 v/v%) at 60°C and stirred until the color turned white.

(5) Base and acid treatment

The bleached sample was washed several times for neutralization and reacted with sodium hydroxide (2 wt%) at 60°C for 2 hours. Next, the alkalized sample was treated with 5 M hydrochloric acid at room temperature for 5 hours to neutralize it.

(6) Cellulose dissolution

The bleached sample was mixed with methanol and stirred vigorously at room temperature for 2 hours, and then filtered while washing the residual sample with methanol. After filtration, 300 ml of dimethylacetamide (DMAc) was mixed with the sample and stirred at room temperature for 2 hours, and then the residual sample was washed with DMAc and filtered. After filtration, 25 ml of DMAc/LiCl solvent was mixed with the sample and stirred overnight at room temperature. The sample thus obtained was centrifuged at 10,000 rpm for 15 minutes to remove undissolved substances and air bubbles, and a cellulose solution was finally obtained.

(7) Manufacturing of biodegradable cellulose film

The prepared cellulose solution was poured onto a glass plate and spread thinly using a film applicator. Thereafter, the glass plate on which the cellulose solution was spread was carefully immersed in a plate containing 1.5 L of ethanol as a coagulating solvent, and after about 10 minutes, when the cellulose gel floated on the glass plate, it was transferred to a plate containing 1486 mL of water + 15 mL of glycerol and immersed for 24 hours to remove the remaining DMAc/LiCl solvent. Thereafter, the cellulose gel was transferred to a polycarbonate sheet, the edge of the cellulose gel was fixed with tape, and the cellulose film was completed by drying for 24 hours.

Fig. 2 (a) is a photograph of a cellulose gel fixed to a border on a polycarbonate sheet, and (b) is a photograph of a completed cellulose film.

Example 2

(6) A cellulose film was manufactured under the same conditions as Example 1, except that acetone was used instead of ethanol as a coagulating solvent in the manufacture of a biodegradable cellulose film.

Example 3

(6) A cellulose film was manufactured under the same conditions as Example 1, except that water was used instead of ethanol as a coagulating solvent in the manufacture of a biodegradable cellulose film.

Comparative Example 1

5 g of kelp stem powder was dissolved in 200 ml of 1% (w/v0) sodium carbonate solution and stirred while heating on a hot plate. 7 ml of 1 N hydrochloric acid solution was added and sufficiently dissolved. 2 g of glycerol was added to prepare a solution from which alginic acid was extracted. This solution was heated in a 90 °C water bath for 30 minutes, poured onto a glass plate, and dried at room temperature for 24 hours to produce a film. Calcium chloride was then treated to form cross-links between alginic acid molecules and calcium ions within the film.

[Experimental example]

Experimental Example 1: Measurement of physical properties of biodegradable plastic films

The thickness of the biodegradable plastic films manufactured according to Examples 1 to 3 was measured using a micrometer (Dial Thickness Gauge 7301, Mitutoyo, Japan) with a precision of 0.01 mm. For the moisture permeability measurement sample, the thickness was measured at the center and four peripheral areas, and the average value was used to calculate the moisture permeability coefficient. For the tensile strength measurement sample, the thickness was also measured at five areas in the longitudinal direction, and the average value was used to calculate the tensile strength of the film.

The tensile strength (TS) and elongation at break (E) of the film were measured using an Instron Universal Testing Machine (Model 3365, Instron Corp., Canton, MA, USA) according to the ASTM (15) standard method. The initial grip-to-grip distance was 5 cm, and the cross-head speed was 50 mm/min. The tensile strength (TS) of the film was calculated by dividing the maximum tension recorded until the film broke by the initial cross-sectional area of the film according to the following Equation 1.

[Formula 1]

TS＝F _max /A

Here, F _max represents the maximum strength (N) at which the film breaks, and A represents the cross-sectional area of the film (m²). The elongation (E) of the film is expressed as a percentage of the initial grip distance by which the film is extended until it breaks, according to Equation 2 below.

[Formula 2]

E(%) = (L/L _o ) × 100

Here, L _o is the distance between the grips, i.e., the initial length of the sample (cm), and L is the length increased until the film breaks (cm). The tensile strength and elongation were measured by taking seven samples from each film, and the measurements were repeated three times and expressed as the average value. The elongation, tensile strength, and modulus were measured three times, and the results are summarized in Table 1 below.

division Coagulating solvent Elongation (%) Tensile strength (MPa) Modulus Example 1 Ethanol 7.08±2.52 113.73±7.24 5372.91±57.94 Example 2 Acetone 2.26±0.42 62.015±1.94 3578.4±34.39 Example 3 water 4.74±0.26 62.60±4.00 3254.05±279.00 Comparative Example 1 water 17.91±2.07 7.37±1.02 -

Accordingly, it can be confirmed that the biodegradable plastic films manufactured according to Examples 1 to 3 of the present invention each exhibit significantly higher tensile strength than the film manufactured by extracting alginic acid from the seaweed stem of Comparative Example 1.

Experimental Example 2: Analysis of transparency of film

The transparency of the biodegradable plastic films manufactured according to Examples 1 to 3 was measured by analyzing the light transmittance at a wavelength of 280 nm in the UV range and a wavelength of 660 nm in the visible light range, and the results are summarized in Table 2 below.

division Coagulating solvent T ₂₈₀ T ₆₆₀ Example 1 Ethanol 82.76±0.66 90.89±0.65 Example 2 Acetone 61.92±1.45 87.09±0.28 Example 3 water 73.42±2.17 78.65±5.86

Accordingly, since the ultraviolet ray transmittance is the highest for the biodegradable plastic film manufactured according to Example 1 and the lowest for the biodegradable plastic film manufactured according to Example 2, it can be seen that when acetone is used as a coagulating solvent to manufacture a biodegradable plastic film, it can have an ultraviolet ray blocking effect. In addition, since the visible light transmittance is also the highest for the biodegradable plastic film manufactured according to Example 1, it can be seen that when ethanol is used as a coagulating solvent, the most transparent biodegradable plastic film can be manufactured.

Figure 3 shows photographs of biodegradable plastic films manufactured according to Examples 1 to 3, respectively, where (a) is a photograph of Example 1, (b) is a photograph of Example 2, and (c) is a photograph of Example 3. When comparing the degree of transparency with the naked eye, it can be confirmed that the transparency of the biodegradable plastic film manufactured according to Example 1 is higher than that of Examples 2 and 3.

Above, the embodiments of the present invention have been described, but those skilled in the art will be able to modify and change the present invention in various ways by adding, changing, deleting or adding components, etc., within the scope that does not depart from the spirit of the present invention described in the claims, and this will also be considered to be included within the scope of the rights of the present invention.

Claims (14)

A method for producing a biodegradable plastic, comprising the step of producing a film by extracting cellulose from seaweed of the genus Ulva sp. , wherein the method for producing a biodegradable plastic film comprises:
(a) a step of producing Ulva powder by crushing Ulva sp. seaweed;
(b) a step of dewaxing the above-mentioned powder;
(c) a step of removing ulvan from the dewaxed safflower powder and washing it;
(d) a step of bleaching the washed seaweed powder;
(e) a step of sequentially performing a base treatment and an acid treatment on the bleached seaweed powder;
(f) a step of preparing a cellulose solution by dissolving the bleached kelp powder in a cellulose solvent; and
(g) a step of immersing the cellulose solution in a coagulating solvent to obtain a cellulose gel and then drying it to produce a cellulose plastic;
In step (f), a process of centrifuging the cellulose solution is additionally performed to remove undissolved substances and air bubbles,
A method for producing a biodegradable plastic for blocking ultraviolet rays, characterized in that in step (g), the coagulating solvent is acetone. delete In the first paragraph,
A method for producing a biodegradable plastic for blocking ultraviolet rays, characterized in that the Ulva sp. seaweed is any one selected from among Ulva ohnoi , Ulva lactuca , Ulva pertusa , Ulva fasciata , Ulva rigida , and Ulva linza . In the first paragraph,
A method for manufacturing a biodegradable plastic for blocking ultraviolet rays, characterized in that in step (b), the dewaxing is performed using any one mixed solvent selected from a mixed solvent of toluene and ethanol, a mixed solvent of acetone and ethanol, and a mixed solvent of hexane and methanol. In the first paragraph,
Step (c) is a method for producing a biodegradable plastic for blocking ultraviolet rays, characterized in that ulvan is removed by mixing with any one chelator selected from ammonium oxalate, oxalate, oxalic acid, acetic acid, malic acid, maleic acid, EDTA (Ethylenediamine tetraacetic acid), DPTA (Diethylenetriamine pentaacetic acid), NTA (Nitrilotriacetic acid), DTPA (Diethylenetriamine pentaacetic acid), HEDTA (N-hydroxyethyl ethylenediamine tetraacetic acid), and IDA (Iminodiacetic acid). In the first paragraph,
A method for manufacturing a biodegradable plastic for blocking ultraviolet rays, characterized in that in step (d), the bleaching is performed using a mixed solution of a chlorine-based oxidizing bleach and an acid. In Article 6,
A method for producing a biodegradable plastic for blocking ultraviolet rays, characterized in that the chlorine-based oxidizing bleach is any one selected from sodium chlorite, sodium hypochlorite, and sodium hypochlorite. In Article 6,
A method for producing a biodegradable plastic for blocking ultraviolet rays, characterized in that the acid is any one selected from acetic acid, formic acid, succinic acid, citric acid, malic acid, maleic acid, and oxalic acid. In Article 6,
A method for producing a biodegradable plastic for blocking ultraviolet rays, characterized in that in step (e), the base treatment and acid treatment are performed using a strong base and a strong acid. In the first paragraph,
A method for producing a biodegradable plastic for blocking ultraviolet rays, characterized in that in step (f), the cellulose solvent is any one selected from among DMAc (N,N-dimethylacetamide)/LiCl, NMMO (N-methylmorpholine-N-oxide)/H ₂ O, Ca(SCN) ₂ (calcium thiocyanate)/H ₂ O, TFA (trifluoroacetic)/chlorinated alkane, and liquid ammonia/ammonium thiocyanate (NH ₄ SCN). delete In the first paragraph,
A method for producing a biodegradable plastic for blocking ultraviolet rays, characterized in that in step (g), the cellulose solution is spread on a plate and then immersed in a coagulating solvent to produce a film-shaped biodegradable plastic. A biodegradable plastic for blocking ultraviolet rays, manufactured according to any one of claims 1, 3 to 10, and 12. In Article 13,
The above biodegradable plastic is a biodegradable plastic for blocking ultraviolet rays, characterized in that it is in the form of a film.