Biodegradable film using calcium carbonate extracted from oyster shells and manufacturing method therefor

Abstract

The present invention relates to a method for manufacturing a biodegradable film using calcium carbonate extracted from oyster shells, and a biodegradable film manufactured thereby. According to the present invention, by utilizing a biodegradable film in the manufacture of wrapping papers, envelopes, and the like requiring biodegradability, the amount of plastic used can be significantly reduced to demonstrate eco-friendliness, and oyster shells treated or left as industrial waste can be utilized as a resource.

Description

Biodegradable film using calcium carbonate extracted from oyster shells and its manufacturing method

[0001] The present invention relates to a biodegradable film using calcium carbonate extracted from oyster shells and a method for manufacturing the same.

[0002] As the coronavirus disease (COVID-19) spreads globally, people are spending more time at home and limiting outdoor activities, leading to significant growth in contactless service businesses. Among these contactless services, businesses like meal kits, delivery food, and takeout coffee are further exacerbating the problem of disposable plastic waste.

[0003] In addition, as the need to transition to a low-carbon economy increases internationally and the importance of sustainable growth strategies has been further highlighted in the wake of COVID-19, the government has implemented policies to address both climate change and economic issues by establishing three major directions for realizing a net-zero society: green transformation of urban, spatial, and living infrastructure; low-carbon, decentralized energy transition; and establishment of a green industry innovation ecosystem.

[0004] Accordingly, the packaging industry is continuing research on eco-friendly packaging materials that can reduce plastic usage through biomass and calcium carbonate (CaCO3) additives.

[0005] Meanwhile, South Korea produces approximately 300,000 tons of oyster shells annually. Most of this is treated as industrial waste, with only a small portion being recycled. In particular, oyster shells that cannot be disposed of due to difficulties such as securing landfill sites and incurring collection and transportation costs are left to pile up or abandoned in vacant coastal areas. Discarded oyster shells cause serious pollution problems, while abandoned shells damage the landscape and, due to the growth of microorganisms attached to the shellfish, cause foul odors and leachate leakage. Therefore, numerous studies are being conducted on methods for processing these oyster shells, as well as recycling or resource recovery.

[0006] For example, many methods have been proposed for manufacturing feed or fertilizer using oyster shells, or for manufacturing solid fuels, but no method has been published for manufacturing a biodegradable film using calcium carbonate extracted from oyster shells.

[0007] The inventors of the present invention have diligently researched effective methods for recycling oyster shells. As a result, they have developed a method for producing high-purity calcium carbonate from oyster shells and using it to manufacture a biodegradable film, thereby completing the present invention.

[0008] Accordingly, the purpose of the present invention is to provide.

[0009] The inventors of this invention have diligently researched effective methods for recycling oyster shells. As a result, they have discovered a method for producing high-purity calcium carbonate from oyster shells and using it to manufacture biodegradable films.

[0010] The present invention relates to a method for producing a biodegradable film using calcium carbonate extracted from oyster shells and a biodegradable film produced thereby.

[0011] Hereinafter, the present invention will be described in more detail.

[0012]

[0013] According to one aspect of the present invention, the present invention provides a method for producing a biodegradable film using calcium carbonate extracted from oyster shells, comprising the following steps:

[0014] A step of extracting calcium carbonate powder from oyster shells;

[0015] A step of preparing a resin composition by mixing a biodegradable resin into the extracted calcium carbonate powder; and

[0016] A step of forming the manufactured resin composition into a biodegradable film.

[0017] In one embodiment of the present invention, the biodegradable resin may be a resin raw material selected from among PLA (Poly Lactic Acid), PBAT (Poly-Butylene Adipate Terephthalate), PHA (Polyhydroxyalkanoate), PBS (Polybutylene succinate), and PCL (Poly Capro Lactone), or a mixture of two or more selected from the above resin raw materials.

[0018] In another embodiment of the present invention, the resin composition may be composed of 10 to 15 parts by weight of calcium carbonate powder and 70 to 80 parts by weight of biodegradable resin.

[0019] Specifically, the biodegradable resin may be composed of 65 to 70 parts by weight of PBAT and 5 to 10 parts by weight of PLA.

[0020] At least one raw material (color raw material) selected from carbon black and sugar may be further added to the above resin composition. The color raw material may be included in an amount of 2 to 5 parts by weight.

[0021] The biodegradable film of the present invention may be formed to a thickness of 10 to 20 μm, 12 to 18 μm, or 15 μm.

[0022] In another embodiment of the present invention, the step of forming the manufactured resin composition into a biodegradable film may be performed by the following steps:

[0023] A step of preparing a biodegradable master batch from a resin composition; and

[0024] A step of forming the manufactured master batch into a biodegradable film.

[0025] The above master batch serves to ensure that calcium carbonate is evenly distributed within the biodegradable film. If calcium carbonate is not evenly distributed within the biodegradable film, the film properties may deteriorate rapidly.

[0026] In another embodiment of the present invention, the step of extracting calcium carbonate powder from the oyster shell may be performed by the following steps:

[0027] A step of preparing a calcium chloride (CaCl2) solution by reacting oyster shells with an acid solution;

[0028] A step of filtering the manufactured calcium chloride (CaCl2) solution;

[0029] A step of producing recrystallized calcium carbonate by adding sodium carbonate (Na2CO3) to a filtered calcium chloride (CaCl2) solution and stirring;

[0030] A step of filtering and washing recrystallized calcium carbonate; and

[0031] A step of drying and powdering the washed recrystallized calcium carbonate.

[0032] According to one embodiment of the present invention, the calcium carbonate powder extraction step of the present invention can increase the purity of calcium carbonate while reducing unnecessary manufacturing processes by using oyster shells without a separate pretreatment (calcination) process.

[0033] Therefore, the biodegradable film of the present invention can prevent agglomeration or deterioration of mechanical properties of calcium carbonate by using high-purity calcium carbonate from which impurities have been removed through the above-described manufacturing step.

[0034] The above acid solution may be one of hydrochloric acid, sulfuric acid, and nitric acid solutions, but is not limited thereto.

[0035]

[0036] According to another aspect of the present invention, the present invention provides a biodegradable film using calcium carbonate extracted from oyster shells, manufactured by the above-described manufacturing method.

[0037] According to one embodiment of the present invention, a biodegradable film using oyster shell extracted calcium carbonate manufactured by the manufacturing method of the present invention may be composed of calcium carbonate powder extracted from oyster shells and a biodegradable resin.

[0038] The biodegradable film of the present invention can improve the flexural modulus, impact strength, rigidity, tear strength, etc. of the biodegradable film by using calcium carbonate extracted from oyster shells as a filler.

[0039] In addition, the use of such fillers significantly reduces the amount of resin used in biodegradable films, thereby reducing carbon dioxide emissions during the film production and disposal process, thereby providing environmental friendliness and reducing the amount of resin used.

[0040] In addition, the biodegradable film of the present invention can increase the biodegradability of the film compared to conventional technologies by not including a coating process using a separate chemical substance.

[0041] Duplicate details of the above biodegradable film manufacturing method and the biodegradable film manufactured thereby are omitted in consideration of the complexity of this specification.

[0042] The present invention relates to a method for manufacturing a biodegradable film using calcium carbonate extracted from oyster shells and a biodegradable film manufactured thereby. According to the present invention, by utilizing a biodegradable film in the production of packaging materials, envelopes, etc. that require biodegradability, the amount of plastic used is significantly reduced, thereby demonstrating environmental friendliness, and oyster shells that are disposed of or abandoned as industrial waste can be recycled.

[0043] FIG. 1 is a perspective view showing components of a biodegradable film using oyster shell extracted calcium carbonate according to one embodiment of the present invention.

[0044] Figure 2 shows the results of measuring the particle size of a biodegradable master batch manufactured according to one embodiment of the present invention.

[0045] Figure 3 is a photograph showing a biodegradable master batch manufactured according to one embodiment of the present invention.

[0046] Figure 4 shows the results of measuring the particle size of a master batch manufactured using chemically untreated oyster shells.

[0047] Figure 5 is a photograph showing a master batch manufactured using oyster shells that have not been chemically treated.

[0048] A method for producing a biodegradable film using calcium carbonate extracted from oyster shells, comprising the following steps:

[0049] A step of extracting calcium carbonate powder from oyster shells;

[0050] A step of preparing a resin composition by mixing a biodegradable resin into the extracted calcium carbonate powder; and

[0051] A step of forming the manufactured resin composition into a biodegradable film.

[0052] Hereinafter, the present invention will be described in more detail through examples. These examples are intended solely to illustrate the present invention more specifically, and it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples.

[0053]

[0054] Example. Preparation of biodegradable film

[0055] 1. Calcium carbonate (CaCO3) powder

[0056] Bulk oyster shells were crushed into 1,000-1,500㎛ sizes (using a multi-mill), and 1g of the crushed powdered oyster shells were added to 5mL of 5M hydrochloric acid (HCl) and reacted at room temperature for 30 minutes. After filtering using a paper filter, 5mL of 1M sodium carbonate (Na2CO3) was added and stirred at 700rpm for 10 minutes. Afterwards, calcium carbonate was produced by washing with ethanol, filtering, and drying at 100℃ for 12 hours. Afterwards, it was crushed into an average particle size of 5㎛ using an ultra micro crusher.

[0057] 2. Biodegradable Master Batch - black / white

[0058] A biodegradable masterbatch was prepared by mixing PBAT (Poly Butylene Adipate Terephthalate) (65-70%), PLA (Polylactic Acid) (5-10%), calcium carbonate powder (15-20%), and colorant (2-5%) (carbon black / fatsogang).

[0059] 3. Biodegradable mulching film

[0060] Biodegradable mulching films (black / white) were manufactured using the manufactured biodegradable master batch using a blown film machine. Each color was produced separately in dedicated equipment according to its characteristics, and the film extrusion temperature was 130-170℃, the production speed was 25 m / min, and cooling was performed by air cooling. The final manufactured biodegradable mulching film was composed of 65-70% PBAT, 5-10% PLA, 12-15% CaCO3, and 2-5% color raw material, similar to the master batch chip, and was manufactured as a roll film with a thickness of 15㎛, a width of 1,200mm, and a length of 500m.

[0061]

[0062] Comparative example. Biodegradable masterbatch

[0063] A biodegradable master batch was prepared in the same manner as in the examples, except that oyster shell powder (not chemically treated) obtained by crushing bulk oyster shells was used instead of the calcium carbonate powder used in the examples.

[0064]

[0065] Experimental Example 1. Evaluation of Biodegradable Masterbatch

[0066] For each biodegradable master batch manufactured in the above examples and comparative examples, the particle size was measured using a particle size analyzer (Mastersizer 3000E, Malvern Panalytical Ltd).

[0067] As a result, as can be seen in FIGS. 2 to 5, in the case of oyster shells (FIG. 4) that were not chemically treated, the average particle size was unevenly distributed, but in the case of the biodegradable master batch (FIG. 2) manufactured by the manufacturing method of the present invention, it was confirmed that the average particle size was 5㎛ or less, which was good. In addition, in the case of oyster shells (FIG. 5) that were not chemically treated, browning occurred during the manufacturing process due to the influence of impurities, which is believed to have occurred due to residual organic matter excluding calcium carbonate at high extrusion temperatures (120 to 160°C). On the other hand, in the case of the biodegradable master batch manufactured by the manufacturing method of the present invention (FIG. 3), it was confirmed that it had excellent purity and was stable without color change at the extrusion temperature.

[0068]

[0069] Experimental Example 2. Evaluation of Biodegradable Mulching Film

[0070] The biodegradable films and oysters manufactured in the above examples were tested for quality across various evaluation criteria. The results are shown in Table 1 below.

[0071] - Self-quality inspection of food packaging materials: Measured according to the Ministry of Food and Drug Safety's Standard for Organizations and Containers and Packaging, Polylactide (PLA) standards. Suitability is determined by checking for lead content of 1 mg / L or less, potassium permanganate content of 10 mg / L or less, and total dissolved content of 30 mg / L or less.

[0072] - Biodegradability: After mixing the test substance with the inoculum and placing it in a composting container, composting is performed under conditions where moisture content, temperature, and oxygen are controlled for a test period of 6 months or less. After that, the amount of carbon dioxide generated among the final biodegradation products such as carbon dioxide, water, and inorganic salts generated from the test substance is continuously measured, and the biodegradability is calculated as a ratio to the theoretical amount of carbon dioxide generated.

[0073] - Tensile strength: Tensile strength is measured by pulling a rod-shaped specimen and examining the applied load and the deformation of the specimen. It is the maximum stress until the specimen breaks due to a tensile load, and is the value calculated by dividing the maximum load until fracture by the original cross-sectional area of ​​the specimen.

[0074] - Analysis of gamma-ray emitting radionuclide content: A total of 6 nuclides, including natural radionuclides (U-238 series, Th-232 series, K-40 analysis) and artificial radionuclides (Cs-134, Cs-137, I-131), were measured using a high-purity germanium gamma-ray detector with a relative efficiency of 60%.

[0075] - Oxygen permeability: Measures the amount of oxygen that permeates a specimen per unit time and per unit area under constant temperature, humidity, and oxygen concentration conditions.

[0076] Evaluation Item Unit Criteria Establishment Basis Implementation Example (Black / White) Self-quality inspection of food packaging materials Pass / Fail Food Code Pass / Fail Biodegradability %KS M ISO 1485562.4 Tensile strength (MD) N / mm 2 ASTM D 88226.5 / 25.9 Tensile strength (TD) N / mm 2 ASTM D 88221.8 / 26.0 Gamma-ray emitting radionuclide content analysis Detected / Not detected High-purity germanium gamma-ray detector Not detected Oxygen penetration cc / m 2 ·dayASTM D 39853275.5 / 3335.2

[0077]

[0078] As can be seen in Table 1 above, the biodegradable film manufactured using the oyster shell extracted calcium carbonate of the present invention has excellent oxygen permeability and biodegradability, excellent tensile strength, and no radioactive nuclides are detected, making it suitable for use as an eco-friendly packaging material.

[0079] The present invention relates to a biodegradable film using calcium carbonate extracted from oyster shells and a method for manufacturing the same.

Claims

1. A method for manufacturing a biodegradable film using calcium carbonate extracted from oyster shells, comprising the following steps: A step of extracting calcium carbonate powder from oyster shells; A step of preparing a resin composition by mixing a biodegradable resin into the extracted calcium carbonate powder; and A step of forming the manufactured resin composition into a biodegradable film.

2. In the first paragraph, the step of extracting calcium carbonate powder from the oyster shell is as follows: A step of preparing a calcium chloride (CaCl2) solution by reacting oyster shells with an acid solution; A step of filtering the manufactured calcium chloride (CaCl2) solution; A step of producing recrystallized calcium carbonate by adding sodium carbonate (Na2CO3) to a filtered calcium chloride (CaCl2) solution and stirring; A step of filtering and washing recrystallized calcium carbonate; and A method for manufacturing a biodegradable film using oyster shell extracted calcium carbonate, comprising the steps of drying and powdering washed recrystallized calcium carbonate.

3. In paragraph 2, A method for manufacturing a biodegradable film using calcium carbonate extracted from oyster shells, wherein the acid solution is one of hydrochloric acid, sulfuric acid and nitric acid solutions.

4. In paragraph 2, A method for manufacturing a biodegradable film using calcium carbonate extracted from oyster shells, wherein the oyster shells are used without a pretreatment process.

5. In the first paragraph, the step of forming the manufactured resin composition into a biodegradable film is as follows: A step of preparing a biodegradable master batch from a resin composition; and A method for manufacturing a biodegradable film using calcium carbonate extracted from oyster shells, comprising the step of forming a manufactured master batch into a biodegradable film.

6. A biodegradable film using calcium carbonate extracted from oyster shells, manufactured by the method of any one of claims 1 to 5.

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