Eco-bio coating agent, method for manufacturing the same, and its applications

Abstract

This invention provides an eco-biocoating agent, a method for producing the same, and a slow-release fertilizer coated with the same on its surface. [Solution] By utilizing gellan gum and chitin / chitosan, the waste problem can be solved because it is biodegradable, has little environmental impact, and can be used as a substitute for plastic. Furthermore, it can be used in slow-release coating fertilizers, allowing the fertilizer components to be released gradually, thereby providing nutrients at the right time for the crops and ensuring the sustained effect of the fertilizer. In addition, the formed coating layer has excellent mechanical strength, high water resistance, and is firmly maintained even in the external environment. Moreover, it is harmless to the human body and can be used in various application fields such as food packaging materials, medical coatings, and biodegradable packaging materials.

Description

[Technical Field]

[0001] This invention relates to an eco-bio-coating agent, more specifically, an environmentally friendly and biodegradable eco-bio-coating agent, a method for producing the same, and its uses, specifically, its use as a slow-release fertilizer coating agent. [Background technology]

[0002] Slow-release fertilizers, also known as leaching-controlled fertilizers, contain plant nutrients in a form that delays plant absorption and utilization after application. They are a type of fertilizer that enhances the functionality of fast-acting fertilizers, such as ammonium nitrate, urea, ammonium phosphate, and calcium chloride, by coating the surface of the fertilizer so that plants can utilize them for a longer period. Such slow-release fertilizers should supply nutrients in the necessary amounts according to the crop's growth stage, and the coating layer must be resistant to breakdown and regulate water movement within the coating layer to ensure a continuous supply of nutrients.

[0003] Currently, due to regulations on chemical resin coatings in developed countries, novel eco-coating methods that offer high slow-release or elution control are being investigated and researched. Core technological research, such as the composition of the coating agent, the moisture permeability of the fertilizer, stability, and environmental compatibility, is emerging as a promising technology.

[0004] Meanwhile, according to data from Statistics Korea and the Korea Credit Information Service, the domestic market size for compound fertilizers has decreased from 1.058 trillion won in 2015 to 920.2 billion won in 2017 due to poor harvests caused by factors such as cold damage, heat waves, and soil collapse during the rainy season, resulting in a decline in shipments of compound fertilizers since 2015. However, due to increased preference for eco-friendly agricultural products and foods, and increased government subsidies, the domestic eco-fertilizer market is expected to grow at an average annual rate of 1.1%, reaching a size of 1.0407 trillion won in 2023.

[0005] Currently, despite the overall agricultural environment showing a decrease in the number of farmers and a reduction in arable land area due to an aging population, the number of farmers cultivating fruit trees and high-quality crops is actually increasing. Therefore, the demand for specialized fertilizers such as slow-release fertilizers, which offer labor-saving benefits, is projected to steadily rise. Furthermore, factors such as population aging, changing values ​​regarding food and consumption, and agriculture integrated with ICT (Information and Communication Technologies) are emerging as macro trends in the compound fertilizer market. In line with this, compound fertilizer companies are developing products that enable improved agricultural productivity and quality with less labor, energy, and nutrients.

[0006] The prior art relating to the present invention is as follows. Korean Patent Registration No. 10-2205869 (registered January 15, 2021) relates to a granular slow-release fertilizer and a method for producing the same, and more specifically, to a granular slow-release fertilizer in which the outer surface of the fertilizer is coated to enhance its slow-release properties, and to a method for producing the same. The aforementioned technology contains 40% by weight of feldspar, 20% by weight of Takamine soil, 25% by weight of bentonite, 1% by weight of microorganisms, 10% by weight of rice bran, 2% by weight of plant extracts, 1% by weight of molasses, and 1% by weight of seaweed extract. The technology comprises a core made of natural minerals including feldspar, Takamine soil, and bentonite, and a coating layer made of microorganisms including chitin-degrading microorganisms, gelatin-degrading microorganisms, and coratin-degrading microorganisms, organic matter including rice bran, plant extracts consisting of bamboo shoot extract, cedar extract, and ginkgo extract, and seaweed extract obtained from molasses and kelp. This relates to a slow-release fertilizer that is safe and provides nutrients suited to the growth stage of crops by adjusting the slow release. While it is partially similar to the present invention in that it uses chitin-degrading microorganisms to construct the coating layer, there is a significant difference in that it does not contain natural polysaccharides such as gellan gum.

[0007] Furthermore, Japanese Patent Application No. 2022-161098 (Filing Date: 2022.10.05.) relates to a coated granular fertilizer and a method for producing the same, wherein the fertilizer is coated with a film made of a coating material, and a pre-coat layer containing a biodegradable resin is installed between the fertilizer and the film. The aforementioned technology involves installing a pre-coat layer between the fertilizer and the film, and provides a method for producing a coated granular fertilizer that suppresses buoyancy and elution, decomposes after its function, and has a low environmental impact, using a biodegradable resin made of polyvinyl alcohol resin, starch, cellulose, lignin, chitin, chitosan, PBS, PBSA, PBAT, PCL, starch polyester, cellulose acetate, PHB, PHBH, PHBV, PLA, PDO, and copolymers thereof. The technology presents chitin as a biodegradable substance, and therefore has a technical configuration that is partially similar to the present invention, but it presents plant-derived substances such as corn starch as polysaccharides, so it is considered to be different from the present invention.

[0008] Furthermore, Japanese Patent Application No. 2022-061365 (Filing Date: March 31, 2022) relates to a coating material for fertilizer, a coated granular fertilizer, and a method for producing the same, and aims to provide a slow-release coated granular fertilizer that does not cause environmental burden due to coating residue after leaching by coating the fertilizer coating material with granular fertilizer. The above technology constitutes a pre-coat layer and includes PGA (polyglycolic acid) as the biodegradable resin used in the pre-coat layer, providing a slow-release coated granular fertilizer, but differs from the present invention in that it does not include carrageenan as a polysaccharide to strengthen polymer bonds. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Republic of Korea Patent Registration No. 10-2205869 (Registered January 15, 2021) [Patent Document 2] Japanese Patent Application No. 2022-161098 (Filed October 5, 2022) [Patent Document 3] Japanese Patent Application No. 2022-061365 (Filed March 31, 2022) [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] The object of the present invention is to provide an eco-biocoating agent that is environmentally friendly and biodegradable, using materials derived from nature. In particular, the present invention aims to provide an eco-biocoating agent that reduces environmental pollution and improves durability and waterproofing by developing a coating that replaces environmentally unfriendly materials such as plastics.

[0011] Another object of the present invention is to provide a slow-release coated fertilizer in which an eco-bio-coating agent is applied to the slow-release coated fertilizer so that the active ingredients of the fertilizer are released at a constant rate, thereby maximizing the efficiency of the fertilizer and reducing environmental pollution caused by excessive fertilizer use. [Means for solving the problem]

[0012] To solve the aforementioned problems, one aspect of the present invention is to provide an eco-biocoating agent containing gellan gum and chitin or chitosan, which are natural substances.

[0013] One embodiment of the present invention is an eco-bio-coating agent comprising gellan gum and chitin or chitosan, wherein the gellan gum forms a three-dimensional gel structure, and crosslinking bonds are formed by an ion exchange reaction between the carboxyl group (-COOH) of the gellan gum and the amine group (-NH2) of the chitosan.

[0014] The gellan gum and chitin or chitosan are contained in a ratio of 1:1 to 1:3 (gellan gum:chitin / chitosan) by weight.

[0015] Ca, which binds to the gellan gum to form further crosslinking bonds. 2+ The Ca further comprises a source and / or carrageenan that undergoes an ion exchange reaction with chitosan.2+ The supply source is selected from calcium nitrate (Ca(NO3)2), calcium chloride (CaCl2), calcium sulfide (CaS), calcium sulfate (CaSO4), calcium carbonate (CaCO3), calcium phosphate (Ca3(PO4)2), calcium hypophosphate (Ca2P2O4), calcium hypophosphite (Ca(H2PO2)2), potassium hydroxide (slaked lime) (Ca(OH)2), calcium oxide (quicklime) (CaO), and calcium acetate (Ca(C2H3O2)2).

[0016] It further contains a plasticizer or an additive for enhancing the flexibility of the film.

[0017] Another aspect of the present invention is to provide a method for producing the eco-biocoting agent of the present invention.

[0018] Specifically, another aspect of the present invention is a method for producing the eco-biocoting agent of the present invention, which includes the step of dissolving gellan gum in water, heating and mixing to obtain a 0.5 - 2 wt% aqueous gellan gum solution (step 1); separately adding chitosan to water, adding a weak acid, and mixing in a weakly acidic environment to obtain a 0.5 - 2 wt% aqueous chitosan solution (step 2); and mixing and stirring the aqueous gellan gum solution of step 1 and the aqueous chitosan solution of step 2 in a ratio of gellan gum:chitosan of 1:1 - 1:3 by weight to obtain a uniform aqueous solution mixture (step 3).

[0019] In step 1, a Ca 2+ supply source is further added at 0.1 - 1 wt%, and in step 3, carrageenan is further added to the aqueous solution mixture at 0.1 - 1 wt%.

[0020] In step 3, a plasticizer or an additive for enhancing the flexibility of the film is further added to the aqueous solution mixture.

[0021] A further embodiment of the present invention is to provide an eco-bio-coating agent of the present invention that provides a slow-release fertilizer having a coating layer formed by uniformly coating the surface of fertilizer particles to be coated, drying, and gelling it.

[0022] The fertilizer is selected from fertilizers, compost, and feed containing nitrogen, phosphorus, and potassium.

[0023] Furthermore, yet another aspect of the present invention is to provide a food packaging material, a medical coating, or a biodegradable packaging material having a coating layer formed by uniformly coating the surface of a packaging material or substrate with the eco-bio coating agent of the present invention, drying it, and allowing it to gel. [Effects of the Invention]

[0024] This invention utilizes gellan gum and chitin / chitosan, which are natural substances, making it biodegradable, having very little impact on the environment, and usable as a substitute for plastics, thus solving the problem of waste.

[0025] Furthermore, the coating agent of the present invention can be used in slow-release coated fertilizers, allowing for the gradual release of fertilizer components. This ensures that nutrients are provided to crops at the appropriate time, guaranteeing the sustained effect of the fertilizer.

[0026] Furthermore, the coating layer formed by the coating agent of the present invention has excellent mechanical strength, high resistance to water, and is firmly maintained even in external environments.

[0027] Furthermore, the coating agent of the present invention is harmless to the human body and can be used in various application fields such as food packaging materials, medical coatings, and biodegradable packaging materials. [Brief explanation of the drawing]

[0028] [Figure 1]Figure 1 is a sequence diagram showing the manufacturing method and coating method of the present invention step by step. [Modes for carrying out the invention]

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by skilled professionals in the art to which this invention pertains. In general, the nomenclature used herein is well known and commonly used in the art.

[0030] In the entirety of this specification, when a part "includes" a certain component, this means that, unless otherwise specifically stated, it does not exclude other components, but rather may include other components.

[0031] The present invention will be described in detail below.

[0032] One embodiment of the present invention provides an eco-bio-coating agent. Specifically, the present invention provides an eco-bio coating agent comprising gellan gum and chitin or chitosan, wherein the gellan gum forms a three-dimensional gel structure, and crosslinking bonds are formed by an ion exchange reaction between the carboxyl group (-COOH) of the gellan gum and the amine group (-NH2) of the chitosan.

[0033] Gellan gum is used as the first component of the eco-bio-coating agent of the present invention.

[0034] Gellan gum is a natural polysaccharide produced by microbial fermentation. Specifically, it is obtained by purifying a high molecular weight polysaccharide gum substance, which is obtained by pure culture fermentation of carbohydrates using Sphingomonas elodea, with isopropyl alcohol, followed by drying and grinding. It is a heteropolysaccharide composed of rhamnose, glucuronic acid, and glucose in a 1:1:2 ratio, and also contains acyl (glyceryl and acetyl) groups as esters linked by O-glycosides.

[0035] When gellan gum is dissolved in water, it releases certain ions in aqueous solution, particularly Ca 2+ It binds to form a gel, and in this process, the molecular chains of gellan gum bind to each other, forming a stable three-dimensional gel structure, and specific ions, especially Ca 2+ Together, they form strong cross-linking bonds, making the gel structure harder and more stable. This enhances the strength and stability of the coating layer. By absorbing water molecules and expanding, it provides high viscosity, allowing the coating layer to form a stable layer even after the evaporation of water, maintaining its physical properties and providing durability to withstand the physical influences of the external environment.

[0036] Chitin or chitosan is used as the second component of the eco-bio-coating agent of the present invention.

[0037] Chitin or chitosan is a natural polymer extracted from the exoskeleton of crustaceans. By deacetylating chitin to convert it to chitosan, even higher water solubility and biodegradability can be obtained. Chitin or chitosan has excellent mechanical strength and durability. In particular, chitosan can form strong bonds through ion exchange reactions with other substances, especially carrageenan, via its amine group (-NH2), thereby improving the strength and durability of the coating layer. Furthermore, chitin or chitosan dissolves easily in acidic environments and provides excellent waterproofing through chemical bonding on the coating surface. When exposed to external moisture or water, the coating layer is not easily damaged by water, maintaining its waterproof function.

[0038] Both gellan gum and chitin / chitosan are natural substances that are easily biodegradable. Gellan gum is broken down by natural microorganisms, and chitin / chitosan is broken down into monosaccharides by microbial enzymes, which are then converted into CO2 and water. Due to these properties, the eco-biocoating agent of the present invention is easily biodegradable in nature and has minimal environmental impact.

[0039] Furthermore, the gellan gum and chitin / chitosan, upon mixing, form crosslinks and hydrogen bonds, thereby improving structural stability. Specifically, the carboxyl group (-COOH) of gellan gum and the amine group (-NH2) of chitosan form strong crosslinks through ion exchange reactions. Such bonds provide the coating layer with structural strength to withstand external impacts and abrasion. This ensures that the coating layer does not easily break and has strong durability against external physical environments. Along with these crosslinks, hydrogen bonds are further formed between gellan gum and chitosan, improving the uniformity and durability of the coating layer. These hydrogen bonds, through interactions between the coating surface and water, ensure that the coating layer adheres well to the surface and remains firmly in place.

[0040] The coating layer formed by this bonding of gellan gum and chitosan exhibits not only excellent mechanical strength but also superior water resistance.

[0041] In the eco-bio-coating agent of the present invention, gellan gum and chitin or chitosan are included in a ratio of 1:1 to 1:3 (gellan gum:chitin / chitosan) by weight. If the ratio deviates from this range, problems arise such as insufficient cross-linking and hydrogen bonding, resulting in degraded structural stability, mechanical strength, and waterproofing.

[0042] The eco-bio-coating agent of the present invention contains Ca as an additional component. 2+ Source and / or carrageenan are used.

[0043] Ca 2+The source of Ca is added to combine with gellan gum during the gelation process of gellan gum to form further cross-linkages. 2+ It is the source of Ca ions. The Ca 2+ source used in the present invention is selected from calcium nitrate (Ca(NO3)2), calcium chloride (CaCl2), calcium sulfide (CaS), calcium sulfate (CaSO4), calcium carbonate (CaCO3), calcium phosphate (Ca3(PO4)2), calcium hypophosphate (Ca2P2O4), calcium hypophosphite (Ca(H2PO2)2), calcium hydroxide (slaked lime) (Ca(OH)2), calcium oxide (quicklime) (CaO), and calcium acetate (Ca(C2H3O2)2). Desirably, it is selected from calcium phosphate (Ca3(PO4)2), calcium hypophosphate (Ca2P2O4), calcium hypophosphite (Ca(H2PO2)2), calcium hydroxide (slaked lime) (Ca(OH)2), calcium oxide (quicklime) (CaO), and calcium acetate (Ca(C2H3O2)2). This content is desirably 20 to 50 parts by weight based on 100 parts by weight of gellan gum. If it is less than the above range, there will be a problem that the further cross-linkages formed thereby are weak and the durability deteriorates. If it exceeds the above range, there will be a problem that no further cross-linkages are formed and the effect of adding the component does not appear.

[0044] Also, carrageenan is a selective additional component added to improve the strength and durability of the coating layer and plays a role in enhancing the physical properties through an ion exchange reaction with chitosan. This content is desirably 20 to 50 parts by weight based on 100 parts by weight of chitosan. If it is less than the above range, there will be a problem that the further ion exchange reaction formed thereby is weak and the role of enhancing the physical properties deteriorates. If it exceeds the above range, there will be a problem that no further ion exchange reaction is formed and the effect of adding the component does not appear.

[0045] The eco-bio coating agent of the present invention selectively contains additives in addition to the aforementioned additional components. The additives may further include plasticizers or additives for increasing the flexibility of the film. The plasticizers or additives for increasing flexibility include all plasticizers and additives for increasing flexibility available in the field that can increase the flexibility of the coating layer formed by the eco-bio coating agent of the present invention. The content is preferably 0.1 to 5% by weight based on 100% by weight of the coating agent. If it is below the above range, a problem arises in that the effect of increasing flexibility is insufficient, and if it exceeds the above range, no improvement in effect is observed with further additions, and a problem arises in that the strength deteriorates due to excessive increase in flexibility.

[0046] Another embodiment of the present invention provides a method for producing the eco-bio-coating agent of the present invention.

[0047] Specifically, the present invention includes the steps of dissolving gellan gum in water, heating and mixing to obtain a 0.5-2% by weight gellan gum aqueous solution (Step 1), Alternatively, the process involves adding chitosan to water, adding a weak acid, and mixing in a weakly acidic environment to obtain a 0.5-2% by weight chitosan aqueous solution (Step 2). The present invention provides a method comprising the steps of: mixing and stirring the gellan gum aqueous solution from step 1 and the chitosan aqueous solution from step 2 in a gellan gum:chitosan ratio of 1:1 to 1:3 by weight to obtain a homogeneous aqueous solution mixture (step 3) (see Figure 1).

[0048] First, as step 0, identify the ingredients, such as gellan gum, chitin / chitosan, and calcium. 2+ The source, carrageenan, and additives are provided. Descriptions of each component have been previously given and are therefore omitted here.

[0049] Step 1 involves dissolving gellan gum in water to obtain an aqueous gellan gum solution. Specifically, gellan gum is mixed with water to produce an aqueous solution at a concentration of 0.5-2% by weight, which is then heated and mixed at a high temperature, for example, 80-90°C, to completely dissolve the gellan gum. If the concentration is below the aforementioned level, it forms an extremely low concentration and weak coating, resulting in a deterioration of waterproofing. If the concentration exceeds the aforementioned level, it becomes uneconomical due to the time and cost involved in production, and despite the use of high concentrations, it results in insufficient strength.

[0050] Here, a small amount of Ca is added to the dissolved gellan gum aqueous solution. 2+ Add ions. Ca 2+ Ions are Ca 2+ Ca added and used as a source 2+ The source is selected from calcium nitrate (Ca(NO3)2), calcium chloride (CaCl2), calcium sulfide (CaS), calcium sulfate (CaSO4), calcium carbonate (CaCO3), calcium phosphate (Ca3(PO4)2), subcalcium phosphate (Ca2P2O4), hypocalcium phosphite (Ca(H2PO2)2), potassium hydroxide (calcined lime) (Ca(OH)2), calcium oxide (quicklime) (CaO), and calcium acetate (Ca(C2H3O2)2), preferably from calcium phosphate (Ca3(PO4)2), subcalcium phosphate (Ca2P2O4), hypocalcium phosphite (Ca(H2PO2)2), potassium hydroxide (calcined lime) (Ca(OH)2), calcium oxide (quicklime) (CaO), and calcium acetate (Ca(C2H3O2)2). The concentration is adjusted to 0.1-1% by weight to form crosslinks. If the range is exceeded, problems arise in which the strength and durability of the coating layer deteriorate.

[0051] In step 2, a separate chitosan aqueous solution is prepared. Specifically, chitosan is mixed with water to produce an aqueous solution at a concentration of 0.5-2% by weight, and it is completely dissolved in a weakly acidic environment with a pH of 4-6. A weak acid, such as acetic acid, can be added to create such a weakly acidic environment. If the concentration is below the above level, it forms an extremely low concentration and weak coating, resulting in a problem of degraded waterproofing. If the concentration exceeds the above level, it is uneconomical due to the time and cost of production, and despite the use of high concentrations, the strength is insufficient.

[0052] In step 3, the gellan gum aqueous solution from step 1 and the chitosan aqueous solution from step 2 are mixed. Specifically, the gellan gum aqueous solution from step 1 and the chitosan aqueous solution from step 2 are mixed in a gellan gum:chitosan ratio of 1:1 to 1:3 by weight, and stirred at room temperature for a predetermined period, for example, about 0.5 to 1 hour, to obtain a homogeneous aqueous solution mixture. If the mixture falls outside this range, the cross-linking and hydrogen bonding that are formed will be insufficient, leading to problems such as deterioration of structural stability, mechanical strength, and waterproofness.

[0053] Here, carrageenan is further added to the aqueous mixture at a concentration of 0.1 to 1% by weight. This is to further improve the strength and durability of the coating layer, as the ion exchange reaction with chitosan makes the coating layer stronger and improves its durability.

[0054] In these steps, the carboxyl groups and amine groups of gellan gum form crosslinks through ion exchange reactions, and hydrogen bonds are also formed, resulting in an increase in the strength of the coating layer.

[0055] Furthermore, plasticizers and other additives can be added to the homogeneous mixed aqueous solution. Adding a small amount of plasticizer increases the flexibility of the coating layer, thereby allowing it to withstand external impacts. Other additives can be added to provide further functionality, and these are readily selectable by those skilled in the art.

[0056] The resulting homogeneous mixed aqueous solution can be evenly coated onto the surface to be coated, and can then be dried and gelled before application.

[0057] Furthermore, yet another aspect of the present invention provides applications for the eco-bio coating agent of the present invention.

[0058] Specifically, the present invention provides a slow-release fertilizer having a coating layer formed by uniformly coating the surface of fertilizer particles with the eco-bio coating agent of the present invention, followed by drying and gelling.

[0059] The fertilizer particles typically used are granular fertilizer particles with a particle size of 2 to 4 mm, which can be easily selected by those skilled in the art. The fertilizers usable in this invention are not particularly limited, as long as they contain nitrogen, phosphorus, and potassium, and are fertilizers, compost, or animal feed, and have a granular shape and are used as slow-release fertilizers.

[0060] Fertilizer coating can be carried out as shown below (see Figure 1).

[0061] First, prepare the fertilizer particles to be coated, dry them beforehand, and then prepare them for coating.

[0062] A uniform aqueous mixture containing gellan gum and chitosan, produced by the above manufacturing method, is evenly coated onto the surface of the fertilizer particles. A uniform thickness can be achieved using a spray method, brush coating, or roll coating method.

[0063] Subsequently, the coated fertilizer is left at room temperature for several minutes to evaporate naturally, or dried using a dryer at a low temperature, for example, 30-50°C. Here, gelling of gellan gum and cross-linking of chitosan occur, forming a strong, flexible coating film that covers the fertilizer.

[0064] Finally, after the coated fertilizer particles are completely dried, their strength, durability, and water resistance are evaluated and adjusted to meet the required properties. After inspecting the coating quality, the fertilizer is packaged and shipped.

[0065] Furthermore, yet another embodiment of the present invention provides a food packaging material, medical coating, or biodegradable packaging material having a coating layer formed by uniformly coating the surface of a packaging material or substrate with the eco-bio coating agent of the present invention, drying, and gelling it.

[0066] The eco-bio-coating agent of the present invention is naturally biodegradable, including natural substances, and therefore has very little impact on the environment. It can be used as a plastic substitute, has excellent mechanical strength, and high water resistance, which allows it to be maintained firmly even in external environments. Furthermore, it is harmless to the human body, so it can be used in various application fields, such as food packaging materials, medical coatings, or biodegradable packaging materials. [Examples]

[0067] The details of the present invention will be described below with reference to examples and experimental cases. These are representative examples of the present invention and do not limit the scope of application of the present invention.

[0068] <Examples 1-3> Production of the Eco-Bio Coating Agent of the Present Invention Step 1: Preparation of gellan gum aqueous solution Gellan gum was added to water and mixed, then heated and stirred at a temperature of 80-90°C to completely dissolve the gellan gum. The concentration of gellan gum at this time is shown in Table 1 below.

[0069] Ca 2+ As a source, calcium chloride (CaCl2) was added and mixed in a range of 0.1 to 1% by weight to produce an aqueous gellan gum solution. Here, Ca 2+ The concentrations of the supply sources are shown in Table 1 below.

[0070] Step 2: Preparation of Chitosan Aqueous Solution In a separate container, chitosan was added to water and mixed, and a small amount of acetic acid was added to create a weakly acidic environment with a pH of 4-6, allowing the chitosan to dissolve completely. The chitosan concentrations at this time are shown in Table 1 below.

[0071] When using chitin, it was deacetylated to convert it to chitosan, which was then used.

[0072] Step 3: Preparation of aqueous solution mixture The gellan gum aqueous solution from Step 1 and the chitosan aqueous solution from Step 2 were mixed in a ratio of 1:1 to 1:3 by weight between gellan gum and chitosan, and the mixture was stirred at room temperature for 30 minutes to produce a homogeneous aqueous solution mixture.

[0073] A small amount of carrageenan and a plasticizer were further added to the aqueous mixture and mixed.

[0074] [Table 1]

[0075] <Example 4> Production of slow-release fertilizer Ten kg of granular urea fertilizer with a particle size of 2-4 mm was placed in a fluidized bed coating machine, and a preheating process was performed at a temperature of 60°C for 10 minutes to fluidize the fertilizer particles and prevent moisture from remaining in the fertilizer.

[0076] The coating agents produced in Examples 1-3 and Comparative Examples 1-3 were applied to the surface of fertilizer to produce slow-release fertilizer. When a single-layer coating was performed by adding water, the concentration of the final coating layer was adjusted to 25% by weight. When two coats were performed, the concentration of the primary coating layer was adjusted to 25% by weight and the concentration of the secondary coating layer to 20% by weight. The coated slow-release fertilizer was produced in this manner. The temperature of the coating layer was 45°C, and the air pressure of the spray nozzle was 2 kg / cm². 2 Primary and secondary coatings were applied using a spray rate of 100g / min.

[0077] The coated fertilizer was left at room temperature for several minutes to allow natural evaporation, or dried in a dryer at 30-50°C. During this process, gelling of gellan gum and cross-linking of chitosan occurred, forming a strong, flexible coating layer that encased the fertilizer.

[0078] The fertilizer coated in Example 1 provides adequate strength and waterproofing, the fertilizer coated in Example 2 enhances the coating by strengthening cross-linking bonds, resulting in superior waterproofing and durability, and the fertilizer coated in Example 3 can achieve very high strength, durability, and waterproofing through a high-concentration combination.

[0079] On the other hand, Ca 2+ In Comparative Example 1, where no ions were added, the cross-linking bond was weak and the durability was insufficient. In Comparative Example 2, the concentrations of gellan gum and chitosan were extremely low, forming a weak coating with poor water resistance. In Comparative Example 3, Ca 2+ Because no ions are added, cross-linking bonds are not formed, resulting in insufficient strength despite the use of high-concentration combinations.

[0080] <Experimental Example 1> Fertilizer Dissolution Rate Test Experimental Example 1 evaluates the leaching rate of coated fertilizer to measure whether the fertilizer components are released into the soil gradually to some extent.

[0081] A sample of the fertilizer produced in Example 4 was taken, and 2.5 g of the pure fertilizer weight (after deducting the weight of the coating agent) was placed in a 250 ml flask filled with distilled water. The flask was then left in a 30°C constant temperature bath, and the amount of urea dissolved in the water over a one-week period was measured using high-performance liquid chromatography (HPLC) equipped with a radioisotope detector (RI detector). The flask was sealed to prevent evaporation of water and nutrients.

[0082] The results of the underwater elution characteristics are shown in Table 2 below. In Table 2 below, a lower elution rate indicates not only superior coating strength and waterproofing of the coating layer, but also superior elution control ability of the coating layer. By analyzing such elution rates, the durability of the coating layer can be evaluated.

[0083] [Table 2]

[0084] As can be seen from Table 2 above, the elution rate of fertilizers coated with the coating agents of Examples 1 to 3 of the present invention increases sequentially over time, and the elution rate progresses slowly, with components remaining even after 6 weeks, indicating that the fertilizer can be supplied over a long period of time. In particular, the fertilizer coated with the coating agent of Example 3 shows the lowest elution rate (75% elution rate after 6 weeks), which indicates that it has the best coating strength and waterproofing properties.

[0085] On the other hand, a rapid dissolution rate was observed in the fertilizers coated with the coating agents of Comparative Examples 1-3, particularly Ca 2+ It can be seen that the release control capacity deteriorates significantly when no supply source is added (Comparative Examples 1 and 3).

Claims

1. Gellan gum and, Contains chitin or chitosan, The gellan gum forms a three-dimensional gel structure. The carboxyl group (-COOH) of gellan gum and the amine group (-NH) of chitosan 2 An eco-bio coating agent characterized by forming crosslink bonds through an ion exchange reaction between )

2. The eco-bio coating agent according to claim 1, characterized in that it contains gellan gum and chitin or chitosan in a ratio of 1:1 to 1:3 (gellan gum:chitin / chitosan) by weight.

3. Ca, which binds to the gellan gum to form further crosslinking bonds. 2+ The source and / or further comprises carrageenan that undergoes an ion exchange reaction with chitosan, The above-mentioned Ca 2+ supply source is calcium nitrate (Ca(NO 3 )) 2 , calcium chloride (CaCl 2 ), calcium sulfide (CaS), calcium sulfate (CaSO 4 ), calcium carbonate (CaCO 3 ), calcium phosphate (Ca 3 (PO 4 ) 2 ), calcium hypophosphite (Ca 2 P 2 O 4 ), calcium phosphite (Ca(H 2 PO 2 ) 2 ), potassium hydroxide (quicklime) (Ca(OH) 2 ), calcium oxide (lime) (CaO), and calcium acetate (Ca(C 2 H 3 O 2 )) 2 ), and is characterized in that it is selected from the above, and is the eco-biocoating agent according to claim 1.

4. The eco-bio coating agent according to claim 1 or 2, further comprising a plasticizer or an additive for increasing the flexibility of the film.

5. A method for producing the eco-bio-coating agent of claim 1, Step 1 involves dissolving gellan gum in water, heating and mixing to obtain a 0.5-2% by weight gellan gum aqueous solution, Step 2 involves adding chitosan to water, adding a weak acid, and mixing in a weakly acidic environment to obtain a 0.5-2% by weight chitosan aqueous solution. A method characterized by comprising the step (step 3) of mixing and stirring the gellan gum aqueous solution from step 1 and the chitosan aqueous solution from step 2 in a gellan gum:chitosan ratio of 1:1 to 1:3 by weight to obtain a homogeneous aqueous solution mixture.

6. In step 1, Ca is added to the gellan gum aqueous solution. 2+ Further add the source at a concentration of 0.1 to 1% by weight. The method according to 5, characterized in that, in step 3, carrageenan is further added to the aqueous mixture in an amount of 0.1 to 1% by weight.

7. The method according to the present invention, characterized in that, in step 3, a plasticizer or an additive for increasing the flexibility of the film is further added to the aqueous mixture.

8. A slow-release fertilizer characterized by having a coating layer formed by evenly coating the surface of fertilizer particles to be coated with the eco-bio-coating agent of claim 1, or the eco-bio-coating agent manufactured by the method of claim 5, and then drying and gelling it.

9. The slow-release fertilizer according to claim 8, characterized in that the fertilizer is selected from fertilizers containing nitrogen, phosphorus, and potassium, compost, and animal feed.

10. A food packaging material, medical coating, or biodegradable packaging material characterized by having a coating layer formed by evenly coating the surface of a packaging material or substrate to be coated with the eco-bio coating agent according to claim 1, or the eco-bio coating agent manufactured by the method of claim 5, and then drying and gelling it.

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